Big-Data-HPC-Platform/system/jlib/jsocket.cpp

/*##############################################################################

    Copyright (C) 2011 HPCC Systems.

    All rights reserved. This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Affero General Public License as
    published by the Free Software Foundation, either version 3 of the
    License, or (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Affero General Public License for more details.

    You should have received a copy of the GNU Affero General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
############################################################################## */


// New IPv6 Version - IN PROGRESS

/*
    TBD IPv6 connect 
    multicast
    look at loopback
*/


#include "platform.h"
#ifdef _VER_C5
#include <clwclib.h>
#else
#include "platform.h"
#include <stdio.h>
#endif
#include <algorithm>

#ifdef _WIN32
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <winsock2.h>
#include <ws2tcpip.h>
#include <signal.h>  
#else
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/tcp.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stddef.h>
#include <errno.h>
#include <net/if.h>
#endif
#include <limits.h>

#include "jmutex.hpp"
#include "jsocket.hpp"
#include "jexcept.hpp"
#include "jio.hpp"
#include "jmisc.hpp"
#include "jthread.hpp"
#include "jqueue.tpp"
#include "jtime.hpp"
#include "jprop.hpp"
#include "jregexp.hpp"
#include "jdebug.hpp"
#include "build-config.h"

// various options 

#define CONNECT_TIMEOUT_REFUSED_WAIT    1000        // maximum to sleep on connect_timeout
#define TRACE_SLOW_BLOCK_TRANSFER   

#define DEFAULT_CONNECT_TIME    (100*1000)      // for connect_wait



#ifndef _WIN32 
#define BLOCK_POLLED_SINGLE_CONNECTS  // NB this is much slower in windows
#define CENTRAL_NODE_RANDOM_DELAY
#else
#define USERECVSEM      // to singlethread BF_SYNC_TRANSFER_PUSH 
#endif

#ifdef _DEBUG
//#define SOCKTRACE
#endif

#ifdef _TESTING
#define _TRACE
#endif

#ifdef _TRACE
#define THROWJSOCKEXCEPTION(exc) \
  { StringBuffer msg; \
    msg.appendf("Target: %s, Raised in: %s, line %d",tracename ,__FILE__, __LINE__); \
    IJSOCK_Exception *e = new SocketException(exc,msg.str());\
    throw e; }
#define THROWJSOCKEXCEPTION2(exc) \
  { StringBuffer msg; \
    msg.appendf("Raised in: %s, line %d",__FILE__, __LINE__); \
    IJSOCK_Exception *e = new SocketException(exc,msg.str());\
    throw e; }
#define LOGERR(err,ref,info) LogErr(err,ref,info,__LINE__,NULL)
#define LOGERR2(err,ref,info) LogErr(err,ref,info,__LINE__,tracename)
    
#else
#define THROWJSOCKEXCEPTION(exc) \
  { IJSOCK_Exception *e = new SocketException(exc);\
    throw e; }
#define THROWJSOCKEXCEPTION2(exc) THROWJSOCKEXCEPTION(exc)
#define LOGERR(err,ref,info)
#define LOGERR2(err,ref,info)
#endif


JSocketStatistics STATS;
static bool IP4only=false;              // slighly faster if we know no IPv6
static bool IP6preferred=false;         // e.g. for DNS and socket create

IpSubNet PreferredSubnet(NULL,NULL);    // set this if you prefer a particular subnet for debugging etc
                                        // e.g. PreferredSubnet("192.168.16.0", "255.255.255.0")


#define IPV6_SERIALIZE_PREFIX (0x00ff00ff)

inline void LogErr(unsigned err,unsigned ref,const char *info,unsigned lineno,const char *tracename)
{
    if (err) 
        PROGLOG("jsocket(%d,%d)%s%s err = %d%s%s",ref,lineno,
           (info&&*info)?" ":"",(info&&*info)?info:"",err,
           (tracename&&*tracename)?" : ":"",(tracename&&*tracename)?tracename:"");
}
    

class jlib_thrown_decl SocketException: public CInterface, public IJSOCK_Exception
{
public:
    IMPLEMENT_IINTERFACE;

    SocketException(int code,const char *_msg=NULL) : errcode(code) 
    {
        if (_msg) 
            msg = strdup(_msg);
        else
            msg = NULL;
    };
    ~SocketException() { free(msg); }
    
    int             errorCode() const { return errcode; }
    static StringBuffer & geterrormessage(int err,StringBuffer &str)
    {
        switch (err) {
        case JSOCKERR_ok:                        return str.append("ok");
        case JSOCKERR_not_opened:                return str.append("socket not opened");
        case JSOCKERR_bad_address:               return str.append("bad address");
        case JSOCKERR_connection_failed:         return str.append("connection failed");
        case JSOCKERR_broken_pipe:               return str.append("connection is broken");
        case JSOCKERR_graceful_close:            return str.append("connection closed other end");
        case JSOCKERR_invalid_access_mode:       return str.append("invalid access mode");
        case JSOCKERR_timeout_expired:           return str.append("timeout expired");
        case JSOCKERR_port_in_use:               return str.append("port in use");
        case JSOCKERR_cancel_accept:             return str.append("cancel accept");
        case JSOCKERR_connectionless_socket:     return str.append("connectionless socket");
        case JSOCKERR_handle_too_large:          return str.append("handle too large");
        case JSOCKERR_bad_netaddr:               return str.append("bad net addr");
        case JSOCKERR_ipv6_not_implemented:      return str.append("IPv6 not implemented");
        // OS errors
#ifdef _WIN32
        case WSAEINTR:              return str.append("WSAEINTR(10004) - Interrupted system call.");
        case WSAEBADF:              return str.append("WSAEBADF(10009) - Bad file number.");
        case WSAEACCES:             return str.append("WSAEACCES(10013) - Permission denied.");
        case WSAEFAULT:             return str.append("WSAEFAULT(10014) - Bad address.");
        case WSAEINVAL:             return str.append("WSAEINVAL(10022) - Invalid argument.");
        case WSAEMFILE:             return str.append("WSAEMFILE(10024) - Too many open files.");
        case WSAEWOULDBLOCK:        return str.append("WSAEWOULDBLOCK(10035) - Operation would block.");
        case WSAEINPROGRESS:        return str.append("WSAEINPROGRESS(10036) - Operation now in progress.");
        case WSAEALREADY:           return str.append("WSAEALREADY(10037) - Operation already in progress.");
        case WSAENOTSOCK:           return str.append("WSAENOTSOCK(10038) - Socket operation on nonsocket.");
        case WSAEDESTADDRREQ:       return str.append("WSAEDESTADDRREQ(10039) - Destination address required.");
        case WSAEMSGSIZE:           return str.append("WSAEMSGSIZE(10040) - Message too long.");
        case WSAEPROTOTYPE:         return str.append("WSAEPROTOTYPE(10041) - Protocol wrong type for socket.");
        case WSAENOPROTOOPT:        return str.append("WSAENOPROTOOPT(10042) - Protocol not available.");
        case WSAEPROTONOSUPPORT:    return str.append("WSAEPROTONOSUPPORT(10043) - Protocol not supported.");
        case WSAESOCKTNOSUPPORT:    return str.append("WSAESOCKTNOSUPPORT(10044) - Socket type not supported.");
        case WSAEOPNOTSUPP:         return str.append("WSAEOPNOTSUPP(10045) - Operation not supported on socket.");
        case WSAEPFNOSUPPORT:       return str.append("WSAEPFNOSUPPORT(10046) - Protocol family not supported.");
        case WSAEAFNOSUPPORT:       return str.append("WSAEAFNOSUPPORT(10047) - Address family not supported by protocol family.");
        case WSAEADDRINUSE:         return str.append("WSAEADDRINUSE(10048) - Address already in use.");
        case WSAEADDRNOTAVAIL:      return str.append("WSAEADDRNOTAVAIL(10049) - Cannot assign requested address.");
        case WSAENETDOWN:           return str.append("WSAENETDOWN(10050) - Network is down.");
        case WSAENETUNREACH:        return str.append("WSAENETUNREACH(10051) - Network is unreachable.");
        case WSAENETRESET:          return str.append("WSAENETRESET(10052) - Network dropped connection on reset.");
        case WSAECONNABORTED:       return str.append("WSAECONNABORTED(10053) - Software caused connection abort.");
        case WSAECONNRESET:         return str.append("WSAECONNRESET(10054) - Connection reset by peer.");
        case WSAENOBUFS:            return str.append("WSAENOBUFS(10055) - No buffer space available.");
        case WSAEISCONN:            return str.append("WSAEISCONN(10056) - Socket is already connected.");
        case WSAENOTCONN:           return str.append("WSAENOTCONN(10057) - Socket is not connected.");
        case WSAESHUTDOWN:          return str.append("WSAESHUTDOWN(10058) - Cannot send after socket shutdown.");
        case WSAETOOMANYREFS:       return str.append("WSAETOOMANYREFS(10059) - Too many references: cannot splice.");
        case WSAETIMEDOUT:          return str.append("WSAETIMEDOUT(10060) - Connection timed out.");
        case WSAECONNREFUSED:       return str.append("WSAECONNREFUSED(10061) - Connection refused.");
        case WSAELOOP:              return str.append("WSAELOOP(10062) - Too many levels of symbolic links.");
        case WSAENAMETOOLONG:       return str.append("WSAENAMETOOLONG(10063) - File name too long.");
        case WSAEHOSTDOWN:          return str.append("WSAEHOSTDOWN(10064) - Host is down.");
        case WSAEHOSTUNREACH:       return str.append("WSAEHOSTUNREACH(10065) - No route to host.");
        case WSASYSNOTREADY:        return str.append("WSASYSNOTREADY(10091) - The network subsystem is unusable.");
        case WSAVERNOTSUPPORTED:    return str.append("WSAVERNOTSUPPORTED(10092) - The Windows Sockets DLL cannot support this application.");
        case WSANOTINITIALISED:     return str.append("WSANOTINITIALISED(10093) - Winsock not initialized.");
        case WSAEDISCON:            return str.append("WSAEDISCON(10101) - Disconnect.");
        case WSAHOST_NOT_FOUND:     return str.append("WSAHOST_NOT_FOUND(11001) - Host not found.");
        case WSATRY_AGAIN:          return str.append("WSATRY_AGAIN(11002) - Nonauthoritative host not found.");
        case WSANO_RECOVERY:        return str.append("WSANO_RECOVERY(11003) - Nonrecoverable error.");
        case WSANO_DATA:            return str.append("WSANO_DATA(11004) - Valid name, no data record of requested type.");
#else
        case ENOTSOCK:              return str.append("ENOTSOCK - Socket operation on non-socket ");
        case EDESTADDRREQ:          return str.append("EDESTADDRREQ - Destination address required ");
        case EMSGSIZE:              return str.append("EMSGSIZE - Message too long ");
        case EPROTOTYPE:            return str.append("EPROTOTYPE - Protocol wrong type for socket ");
        case ENOPROTOOPT:           return str.append("ENOPROTOOPT - Protocol not available ");
        case EPROTONOSUPPORT:       return str.append("EPROTONOSUPPORT - Protocol not supported ");
        case ESOCKTNOSUPPORT:       return str.append("ESOCKTNOSUPPORT - Socket type not supported ");
        case EOPNOTSUPP:            return str.append("EOPNOTSUPP - Operation not supported on socket ");
        case EPFNOSUPPORT:          return str.append("EPFNOSUPPORT - Protocol family not supported ");
        case EAFNOSUPPORT:          return str.append("EAFNOSUPPORT - Address family not supported by protocol family ");
        case EADDRINUSE:            return str.append("EADDRINUSE - Address already in use ");
        case EADDRNOTAVAIL:         return str.append("EADDRNOTAVAIL - Can't assign requested address ");
        case ENETDOWN:              return str.append("ENETDOWN - Network is down ");
        case ENETUNREACH:           return str.append("ENETUNREACH - Network is unreachable ");
        case ENETRESET:             return str.append("ENETRESET - Network dropped connection because of reset ");
        case ECONNABORTED:          return str.append("ECONNABORTED - Software caused connection abort ");
        case ECONNRESET:            return str.append("ECONNRESET - Connection reset by peer ");
        case ENOBUFS:               return str.append("ENOBUFS - No buffer space available ");
        case EISCONN:               return str.append("EISCONN - Socket is already connected ");
        case ENOTCONN:              return str.append("ENOTCONN - Socket is not connected ");
        case ESHUTDOWN:             return str.append("ESHUTDOWN - Can't send after socket shutdown ");
        case ETOOMANYREFS:          return str.append("ETOOMANYREFS - Too many references: can't splice ");
        case ETIMEDOUT:             return str.append("ETIMEDOUT - Connection timed out ");
        case ECONNREFUSED:          return str.append("ECONNREFUSED - Connection refused ");
        case EHOSTDOWN:             return str.append("EHOSTDOWN - Host is down ");
        case EHOSTUNREACH:          return str.append("EHOSTUNREACH - No route to host ");
        case EWOULDBLOCK:           return str.append("EWOULDBLOCK - operation already in progress");
        case EINPROGRESS:           return str.append("EINPROGRESS - operation now in progress ");
#endif
        }
        IException *ose = MakeOsException(err);
        ose->errorMessage(str);
        ose->Release();
        return str;
    }   
    StringBuffer &  errorMessage(StringBuffer &str) const
    { 
        if (msg)
            return geterrormessage(errcode,str).append('\n').append(msg); 
        return geterrormessage(errcode,str); 
    }
    MessageAudience errorAudience() const 
    { 
        switch (errcode) {
        case JSOCKERR_port_in_use:               
            return MSGAUD_operator; 
        }
        return MSGAUD_user; 
    }
private:
    int     errcode;
    char *msg;
};

IJSOCK_Exception *IPv6NotImplementedException(const char *filename,unsigned lineno)
{
    StringBuffer msg;
    msg.appendf("%s(%d)",filename,lineno);
    return new SocketException(JSOCKERR_ipv6_not_implemented,msg.str());
}

struct MCASTREQ
{
   struct in_addr imr_multiaddr;   /* multicast group to join */
   struct in_addr imr_interface;   /* interface to join on    */
   MCASTREQ(const char *mcip)
   {
        imr_multiaddr.s_addr = inet_addr(mcip);
        imr_interface.s_addr = htonl(INADDR_ANY);

   }

};

#ifdef __APPLE__
#ifndef MSG_NOSIGNAL
#define MSG_NOSIGNAL 0x4000
#endif
#endif

#if defined( _WIN32)
#define T_SOCKET SOCKET
#define T_FD_SET fd_set
#define XFD_SETSIZE FD_SETSIZE
#define ETIMEDOUT WSAETIMEDOUT
#define ECONNREFUSED WSAECONNREFUSED
#define XFD_ZERO(s) FD_ZERO(s)
#define SEND_FLAGS 0
#define BADSOCKERR(err) ((err==WSAEBADF)||(err==WSAENOTSOCK))
#define CHECKSOCKRANGE(s)
#elif defined(__FreeBSD__) || defined(__APPLE__)
#define XFD_SETSIZE FD_SETSIZE
#define T_FD_SET fd_set
#define XFD_ZERO(s) FD_ZERO(s)
#define T_SOCKET int
#define SEND_FLAGS (MSG_NOSIGNAL)
#define BADSOCKERR(err) ((err==EBADF)||(err==ENOTSOCK))
#define CHECKSOCKRANGE(s)
#else
#define XFD_SETSIZE 32768
struct xfd_set { __fd_mask fds_bits[XFD_SETSIZE / __NFDBITS]; }; // define our own
// linux 64 bit
#ifdef __linux__
#ifdef __x86_64__
#undef __FDMASK
#define __FDMASK(d)     (1UL << ((d) % __NFDBITS))
#undef __FDELT
#define __FDELT(d)      ((d) / __NFDBITS)
#undef __FD_SET
#define __FD_SET(d, s)     (__FDS_BITS (s)[__FDELT(d)] |= __FDMASK(d))
#undef __FD_ISSET
#define __FD_ISSET(d, s)   ((__FDS_BITS (s)[__FDELT(d)] & __FDMASK(d)) != 0)
#endif
#define CHECKSOCKRANGE(s) { if (s>=XFD_SETSIZE) THROWJSOCKEXCEPTION2(JSOCKERR_handle_too_large); }
#endif
// end 64 bit
#define T_FD_SET xfd_set
#define XFD_ZERO(s) memset(s,0,sizeof(xfd_set))
#define T_SOCKET int
#define SEND_FLAGS (MSG_NOSIGNAL)
#define BADSOCKERR(err) ((err==EBADF)||(err==ENOTSOCK))
#endif
#ifdef CENTRAL_NODE_RANDOM_DELAY
static SocketEndpointArray CentralNodeArray;
#endif
enum SOCKETMODE { sm_tcp_server, sm_tcp, sm_udp_server, sm_udp, sm_multicast_server, sm_multicast};

class CSocket: public CInterface, public ISocket
{
public:
    IMPLEMENT_IINTERFACE;

    static          CriticalSection crit;
protected:
    friend class CSocketConnectWait;
    enum { ss_open, ss_shutdown, ss_close, ss_pre_open } state;
    T_SOCKET        sock;
    char*           hostname;   // host address
    unsigned short  hostport;   // host port
    SOCKETMODE      sockmode;
    IpAddress       targetip;
    SocketEndpoint  returnep;   // set by set_return_addr
    
    MCASTREQ    *   mcastreq;
    size32_t        nextblocksize;
    unsigned        blockflags;
    unsigned        blocktimeoutms;
    bool            owned;
    enum            {accept_not_cancelled, accept_cancel_pending, accept_cancelled} accept_cancel_state;
    bool            in_accept;
    bool            nonblocking;
    bool            nagling;
    static unsigned connectingcount;
#ifdef USERECVSEM
    static Semaphore receiveblocksem;
    bool            receiveblocksemowned; // owned by this socket
#endif
#ifdef _TRACE
    char        *   tracename;
#endif
    
public:
    void        open(int listen_queue_size,bool reuseports=false);
    bool        connect_timeout( unsigned timeout, bool noexception);
    void        connect_wait( unsigned timems);
    void        udpconnect();

    void        read(void* buf, size32_t min_size, size32_t max_size, size32_t &size_read,unsigned timeoutsecs);
    void        readtms(void* buf, size32_t min_size, size32_t max_size, size32_t &size_read, unsigned timedelaysecs);
    void        read(void* buf, size32_t size);
    size32_t    write(void const* buf, size32_t size);
    size32_t    write_multiple(unsigned num,void const**buf, size32_t *size);
    size32_t    udp_write_to(SocketEndpoint &ep,void const* buf, size32_t size);
    void        close();
    void        errclose();
    bool        connectionless() { return (sockmode!=sm_tcp)&&(sockmode!=sm_tcp_server); }
    void        shutdown(unsigned mode);

    ISocket*    accept(bool allowcancel);
    int         wait_read(unsigned timeout);
    int         wait_write(unsigned timeout);
    int         name(char *name,size32_t namemax);
    int         peer_name(char *name,size32_t namemax);
    SocketEndpoint &getPeerEndpoint(SocketEndpoint &ep);
    IpAddress & getPeerAddress(IpAddress &addr);
    void        set_return_addr(int port,const char *name);  // sets returnep
    void        cancel_accept();
    size32_t    get_max_send_size();
    bool        set_nonblock(bool on=true);
    bool        set_nagle(bool on);
    void        set_linger(int lingersecs); 
    void        set_keep_alive(bool set);
    virtual void set_inherit(bool inherit=false);
    virtual bool check_connection();

    
    // Block functions
    void        set_block_mode(unsigned flags,size32_t recsize=0,unsigned timeoutms=0);
    bool        send_block(const void *blk,size32_t sz);
    size32_t        receive_block_size();
    size32_t        receive_block(void *blk,size32_t sz);

    size32_t        get_send_buffer_size();
    void        set_send_buffer_size(size32_t sz);

    bool        join_multicast_group(SocketEndpoint &ep);   // for udp multicast
    bool        leave_multicast_group(SocketEndpoint &ep);  // for udp multicast

    size32_t        get_receive_buffer_size();
    void        set_receive_buffer_size(size32_t sz);

    size32_t        avail_read();

    int         pre_connect(bool block);
    int         post_connect();

    CSocket(const SocketEndpoint &_ep,SOCKETMODE smode,const char *name);
    CSocket(T_SOCKET new_sock,SOCKETMODE smode,bool _owned);

    virtual ~CSocket();

    unsigned OShandle()
    {
        return (unsigned)sock;
    }

private:

    int closesock()
    {
        if (sock!=INVALID_SOCKET) {
            T_SOCKET s = sock;
            sock = INVALID_SOCKET;
            STATS.activesockets--;
    #ifdef SOCKTRACE
            PROGLOG("SOCKTRACE: Closing socket %x %d (%x)", s, s, this);
    #endif
    #ifdef _WIN32
            return ::closesocket(s);
    #else
            return ::close(s);
    #endif
        }
        else
            return 0;
    }
};

CriticalSection CSocket::crit;
unsigned CSocket::connectingcount=0;
#ifdef USERECVSEM
Semaphore CSocket::receiveblocksem(2);
#endif


#ifdef _WIN32
class win_socket_library 
{
    static bool initdone; // to prevent dependancy probs very early on (e.g. jlog)
public:
    win_socket_library() { init(); }
    bool init()
    {
        if (initdone)
            return true;
        WSADATA wsa;
        if (WSAStartup(MAKEWORD(2, 2), &wsa) != 0) {
            if (WSAStartup(MAKEWORD(1, 1), &wsa) != 0) {
                MessageBox(NULL,"Failed to initialize windows sockets","JLib Socket Error",MB_OK);
                return false;
            }
        }
        initdone = true;
        return true;
    }
    ~win_socket_library() 
    {
        WSACleanup();
    }
};

bool win_socket_library::initdone = false;
static win_socket_library ws32_lib;

#define ERRNO() WSAGetLastError()
#define EADDRINUSE WSAEADDRINUSE
#define EINTRCALL WSAEINTR
#define ECONNRESET WSAECONNRESET
#define ECONNABORTED WSAECONNABORTED
#define ENOTCONN WSAENOTCONN
#define EWOULDBLOCK WSAEWOULDBLOCK
#define EINPROGRESS WSAEINPROGRESS
#define ENOTSOCK WSAENOTSOCK


struct j_sockaddr_in6 {
    short   sin6_family;        /* AF_INET6 */
    u_short sin6_port;          /* Transport level port number */
    u_long  sin6_flowinfo;      /* IPv6 flow information */
    struct in_addr6 sin6_addr;  /* IPv6 address */
    u_long sin6_scope_id;       /* set of interfaces for a scope */
};

typedef union {
    struct sockaddr sa;
    struct j_sockaddr_in6 sin6;
    struct sockaddr_in sin;
} J_SOCKADDR;

#define DEFINE_SOCKADDR(name) J_SOCKADDR name; memset(&name,0,sizeof(J_SOCKADDR))


static int _inet_pton(int af, const char* src, void* dst)
{
    
    DEFINE_SOCKADDR(u);
    
    int address_length;
    
    switch (af) {
    case AF_INET:
        u.sin.sin_family    = AF_INET;
        address_length = sizeof (u.sin);
        break;
        
    case AF_INET6:
        u.sin6.sin6_family  = AF_INET6;
        address_length = sizeof (u.sin6);
        break;
        
    default:
#ifdef EAFNOSUPPORT
        errno = EAFNOSUPPORT;
#else
        errno = 52;
#endif
        return -1;
    }
    ws32_lib.init();
    int ret = WSAStringToAddress ((LPTSTR) src, af, NULL, &u.sa, &address_length);
    if (ret == 0) {
        switch (af) {
        case AF_INET:
            memcpy (dst, &u.sin.sin_addr, sizeof (struct in_addr));
            break;
            
        case AF_INET6:
            memcpy (dst, &u.sin6.sin6_addr, sizeof (u.sin6.sin6_addr));
            break;
        }
        return 1;
    }
    errno = WSAGetLastError();  
    // PROGLOG("errno = %d",errno);
    return 0;
}

static const char * _inet_ntop (int af, const void *src, char *dst, socklen_t cnt)
{
    /* struct sockaddr can't accomodate struct sockaddr_in6. */
    DEFINE_SOCKADDR(u);

    DWORD dstlen = cnt;
    size_t srcsize;
    
    memset(&u,0,sizeof(u));
    switch (af) {
    case AF_INET:
        u.sin.sin_family = AF_INET;
        u.sin.sin_addr = *(struct in_addr *) src;
        srcsize = sizeof (u.sin);
        break;
    case AF_INET6:
        u.sin6.sin6_family = AF_INET6;
        memcpy(&u.sin6.sin6_addr,src,sizeof(in_addr6));
        srcsize = sizeof (u.sin6);
        break;
    default:
        return NULL;
    }
    
    ws32_lib.init();
    if (WSAAddressToString (&u.sa, srcsize, NULL, dst, &dstlen) != 0) {
        errno = WSAGetLastError();
        return NULL;
    }
    return (const char *) dst;
}


int inet_aton (const char *name, struct in_addr *addr)
{
    addr->s_addr = inet_addr (name);
    return (addr->s_addr == (u_long)-1)?1:0;        // 255.255.255.255 has had it here
}



#else
#define _inet_ntop inet_ntop
#define _inet_pton inet_pton

#define in_addr6 in6_addr 

typedef union {
    struct sockaddr sa;
    struct sockaddr_in6 sin6;
    struct sockaddr_in sin;
} J_SOCKADDR;

#define DEFINE_SOCKADDR(name) J_SOCKADDR name; memset(&name,0,sizeof(J_SOCKADDR))


#define EINTRCALL EINTR
#define ERRNO() (errno)
#ifndef INADDR_NONE
#define INADDR_NONE (-1)
#endif
#endif

#ifndef INET6_ADDRSTRLEN
#define INET6_ADDRSTRLEN 65
#endif


inline socklen_t setSockAddr(J_SOCKADDR &u, const IpAddress &ip,unsigned short port)
{
    if (!IP6preferred) {
        if (ip.getNetAddress(sizeof(in_addr),&u.sin.sin_addr)==sizeof(in_addr)) {
            u.sin.sin_family = AF_INET; 
            u.sin.sin_port = htons(port);
            return sizeof(u.sin);
        }
    }
    if (IP4only)
        IPV6_NOT_IMPLEMENTED();
    ip.getNetAddress(sizeof(in_addr6),&u.sin6.sin6_addr);
    u.sin6.sin6_family = AF_INET6; 
    u.sin6.sin6_port = htons(port);
    return sizeof(u.sin6);
}

inline socklen_t setSockAddrAny(J_SOCKADDR &u, unsigned short port)
{
    if (IP6preferred) {
#ifdef _WIN32
        IN6ADDR_SETANY((PSOCKADDR_IN6)&u.sin6.sin6_addr);
#else
        memcpy(&u.sin6.sin6_addr,&in6addr_any,sizeof(in_addr6));
#endif
        u.sin6.sin6_family= AF_INET6;                           
        u.sin6.sin6_port = htons(port);
        return sizeof(u.sin6);
    }
    u.sin.sin_addr.s_addr = htonl(INADDR_ANY);
    u.sin.sin_family= AF_INET;                          
    u.sin.sin_port = htons(port);
    return sizeof(u.sin);
}

inline void getSockAddrEndpoint(const J_SOCKADDR &u, socklen_t ul, SocketEndpoint &ep)
{
    if (ul==sizeof(u.sin)) {
        ep.setNetAddress(sizeof(in_addr),&u.sin.sin_addr);
        ep.port = htons(u.sin.sin_port); 
    }
    else {
        ep.setNetAddress(sizeof(in_addr6),&u.sin6.sin6_addr);
        ep.port = htons(u.sin6.sin6_port); 
    }
}



/* might need fcntl(F_SETFL), or ioctl(FIONBIO) */
/* Posix.1g says fcntl */

#if defined(O_NONBLOCK) 

bool CSocket::set_nonblock(bool on)
{
    int flags = fcntl(sock, F_GETFL, 0);
    if (flags == -1)
        return nonblocking;
    if (on)
        flags |= O_NONBLOCK;
    else
        flags &= ~O_NONBLOCK;
    if (fcntl(sock, F_SETFL, flags)==0) {
        bool wasNonBlocking = nonblocking;
        nonblocking = on;
        return wasNonBlocking;
    }
    return nonblocking;
}



#else

bool CSocket::set_nonblock(bool on)
{
#ifdef _WIN32
    u_long yes = on?1:0;
    if (ioctlsocket(sock, FIONBIO, &yes)==0) {
#else
    int yes = on?1:0;
    if (ioctl(sock, FIONBIO, &yes)==0) {
#endif
        bool wasNonBlocking = nonblocking;
        nonblocking = on;
        return wasNonBlocking;
    }
    return nonblocking;
}

#endif

bool CSocket::set_nagle(bool on)
{
    bool ret = nagling;
    nagling = on;
    int enabled = !on;
    if (setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, (char*)&enabled, sizeof(enabled)) != 0) {
        nagling = !on;
    }
    return ret;
}

void CSocket::set_inherit(bool inherit)
{
#ifndef _WIN32
    long flag = fcntl(sock, F_GETFD);
    if(inherit)
        flag &= ~FD_CLOEXEC;
    else
        flag |= FD_CLOEXEC;
    fcntl(sock, F_SETFD, flag);
#endif
}

size32_t CSocket::avail_read()
{
#ifdef _WIN32
    u_long avail;
    if (ioctlsocket(sock, FIONREAD, &avail)==0) 
#else
    int avail;
    if (ioctl(sock, FIONREAD, &avail)==0) 
#endif
        return (size32_t)avail;
    int err = ERRNO();
    LOGERR2(err,1,"avail_read");
    return 0;
}


int CSocket::pre_connect (bool block)
{
    assertex(hostname);
    DEFINE_SOCKADDR(u);
    if (targetip.isNull()) {
        set_return_addr(hostport,hostname);
        targetip.ipset(returnep);
    }
    socklen_t ul = setSockAddr(u,targetip,hostport);
    sock = ::socket(u.sa.sa_family, SOCK_STREAM, targetip.isIp4()?0:PF_INET6);
    owned = true;
    state = ss_pre_open;            // will be set to open by post_connect
    if (sock == INVALID_SOCKET) {
        int err = ERRNO();
        THROWJSOCKEXCEPTION(err);
    }
    STATS.activesockets++;
    int err = 0;
    set_nonblock(!block);
    int rc = ::connect(sock, &u.sa, ul);
    if (rc==SOCKET_ERROR) {
        err = ERRNO();
        if ((err != EINPROGRESS)&&(err != EWOULDBLOCK)&&(err != ETIMEDOUT)&&(err!=ECONNREFUSED))    // handled by caller
            LOGERR2(err,1,"pre_connect");
    }
#ifdef SOCKTRACE
    PROGLOG("SOCKTRACE: pre-connected socket%s %x %d (%x) err=%d", block?"(block)":"", sock, sock, (int)this, err);
#endif
    return err;
}

int CSocket::post_connect ()
{
    set_nonblock(false);
    int err = 0;
    socklen_t  errlen = sizeof(err);
    int rc = getsockopt(sock, SOL_SOCKET, SO_ERROR, (char *)&err, &errlen); // check for error
    if ((rc!=0)&&!err)
        err = ERRNO();  // some implementations of getsockopt duff
    if (err==0) {
        nagling = true;
        set_nagle(false);
        state = ss_open;
    }
    else if ((err!=ETIMEDOUT)&&(err!=ECONNREFUSED)) // handled by caller
        LOGERR2(err,1,"post_connect");
    return err;
}


void CSocket::open(int listen_queue_size,bool reuseports)
{
    if (IP6preferred)
        sock = ::socket(AF_INET6, connectionless()?SOCK_DGRAM:SOCK_STREAM, PF_INET6);
    else
        sock = ::socket(AF_INET, connectionless()?SOCK_DGRAM:SOCK_STREAM, 0);
    if (sock == INVALID_SOCKET) {
        THROWJSOCKEXCEPTION(ERRNO());
    }
    STATS.activesockets++;

#ifdef SOCKTRACE
    PROGLOG("SOCKTRACE: opened socket %x %d (%x)", sock,sock,this);
#endif

    if ((hostport==0)&&(sockmode==sm_udp)) {
        state = ss_open;
#ifdef SOCKTRACE
        PROGLOG("SOCKTRACE: opened socket return udp");
#endif
        set_inherit(false);
        return;
    }

#ifndef _WIN32
    reuseports = true;  // for some reason linux requires reuse ports
#endif
    if (reuseports) {
        int on = 1;
        setsockopt( sock, SOL_SOCKET, SO_REUSEADDR, (char *)&on, sizeof(on));
    }

    DEFINE_SOCKADDR(u);
    socklen_t  ul;
    if (hostname) {
        if (targetip.isNull()) {
            set_return_addr(hostport,hostname);
            targetip.ipset(returnep);
        }
        ul = setSockAddr(u,targetip,hostport);
    }
    else 
        ul = setSockAddrAny(u,hostport);
    int saverr;
    if (::bind(sock, &u.sa, ul) != 0) {
        saverr = ERRNO();
        if (saverr==EADDRINUSE) {   // don't log as error (some usages probe ports)
ErrPortInUse:
            closesock();
            char msg[1024]; 
            sprintf(msg,"Target: %s, port = %d, Raised in: %s, line %d",tracename,(int)hostport,__FILE__, __LINE__); 
            IJSOCK_Exception *e = new SocketException(JSOCKERR_port_in_use,msg);
            throw e; 
        }
        else {
            closesock();
            THROWJSOCKEXCEPTION(saverr);
        }
    }
    if (!connectionless()) {
        if (::listen(sock, listen_queue_size) != 0) {
            saverr = ERRNO();
            if (saverr==EADDRINUSE)
                goto ErrPortInUse;
            closesock();
            THROWJSOCKEXCEPTION(saverr);
        }
    }
    if (mcastreq) {
        if (setsockopt(sock, IPPROTO_IP, IP_ADD_MEMBERSHIP,(char*)mcastreq, sizeof(*mcastreq))!=0) {
            saverr = ERRNO();
            closesock();
            THROWJSOCKEXCEPTION(saverr);
        }
    }

    state = ss_open;
#ifdef SOCKTRACE
    PROGLOG("SOCKTRACE: opened socket return");
#endif
    set_inherit(false);
}



ISocket* CSocket::accept(bool allowcancel)
{
    if ((accept_cancel_state!=accept_not_cancelled) && allowcancel) {
        accept_cancel_state=accept_cancelled;
        return NULL;
    }
    if (state != ss_open) {
        ERRLOG("invalid accept, state = %d",(int)state);
        THROWJSOCKEXCEPTION(JSOCKERR_not_opened);
    }
    if (connectionless()) {
        THROWJSOCKEXCEPTION(JSOCKERR_connectionless_socket);
    }
    T_SOCKET newsock;
    loop {
        in_accept = true;
        newsock = (sock!=INVALID_SOCKET)?::accept(sock, NULL, NULL):INVALID_SOCKET;
        in_accept = false;
    #ifdef SOCKTRACE
        PROGLOG("SOCKTRACE: accept created socket %x %d (%x)", newsock,newsock,this);
    #endif

        if (newsock!=INVALID_SOCKET) {
            if ((sock==INVALID_SOCKET)||(accept_cancel_state==accept_cancel_pending)) {
                ::close(newsock);
                newsock=INVALID_SOCKET;
            }
            else {
                accept_cancel_state = accept_not_cancelled;
                break;
            }
        }
        int saverr;
        saverr = ERRNO();
        if ((sock==INVALID_SOCKET)||(accept_cancel_state==accept_cancel_pending)) {
            accept_cancel_state = accept_cancelled;
            if (allowcancel)
                return NULL;
            THROWJSOCKEXCEPTION(JSOCKERR_cancel_accept);
        }
        if (saverr != EINTRCALL) {
            accept_cancel_state = accept_not_cancelled;
            THROWJSOCKEXCEPTION(saverr);
        }
    }
    if (state != ss_open) {
        accept_cancel_state = accept_cancelled;
        if (allowcancel)
            return NULL;
        THROWJSOCKEXCEPTION(JSOCKERR_cancel_accept);
    }
    CSocket *ret = new CSocket(newsock,sm_tcp,true);
    ret->set_inherit(false);
    return ret;

}


void CSocket::set_linger(int lingertime)
{
    struct linger l;
    l.l_onoff = (lingertime>=0)?1:0;
    l.l_linger = (lingertime>=0)?lingertime:0;
    if (setsockopt(sock, SOL_SOCKET, SO_LINGER, (char*)&l, sizeof(l)) != 0) {
        WARNLOG("Linger not set");
    }
}

void CSocket::set_keep_alive(bool set)
{
    int on=set?1:0;
    if (setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (char*)&on, sizeof(on)) != 0) {
        WARNLOG("KeepAlive not set");
    }
}


int CSocket::name(char *retname,size32_t namemax)
{
    if (!retname)
        namemax = 0;
    if (namemax)
        retname[0] = 0;
    retname[0] = 0;
    if (state != ss_open) {
        THROWJSOCKEXCEPTION(JSOCKERR_not_opened);
    }
    DEFINE_SOCKADDR(u);
    socklen_t ul = sizeof(u);       
    if (::getsockname(sock,&u.sa, &ul)<0) {
        THROWJSOCKEXCEPTION(ERRNO());
    }
    SocketEndpoint ep;
    getSockAddrEndpoint(u,ul,ep);
    StringBuffer s;
    ep.getIpText(s);
    if (namemax>=1) {
        if (namemax-1<s.length())
            s.setLength(namemax-1);
        memcpy(retname,s.str(),s.length());
    }
    return ep.port;
}

int CSocket::peer_name(char *retname,size32_t namemax)
{
    // should not raise exceptions
    int ret = 0;
    if (!retname)
        namemax = 0;
    if (namemax)
        retname[0] = 0;
    if (state != ss_open) {
        return -1; // don't log as used to test socket
    }
    StringBuffer s;
    if (sockmode==sm_udp_server) { // udp server
        returnep.getIpText(s);
        ret =  returnep.port;
    }   
    else {
        DEFINE_SOCKADDR(u);
        socklen_t ul = sizeof(u);       
        if (::getpeername(sock,&u.sa, &ul)<0)           
            return -1;      // don't log as used to test socket
        SocketEndpoint ep;
        getSockAddrEndpoint(u,ul,ep);
        ep.getIpText(s);
        ret = ep.port;
    }
    if (namemax>1) {
        if (namemax-1<s.length())
            s.setLength(namemax-1);
        memcpy(retname,s.str(),s.length()+1);
    }
    return ret;
}

SocketEndpoint &CSocket::getPeerEndpoint(SocketEndpoint &ep)
{
    if (state != ss_open) {
        THROWJSOCKEXCEPTION(JSOCKERR_not_opened);
    }
    StringBuffer s;
    if (sockmode==sm_udp_server) { // udp server
        ep.set(returnep);
    }   
    else {
        DEFINE_SOCKADDR(u);
        socklen_t ul = sizeof(u);       
        if (::getpeername(sock,&u.sa, &ul)<0) {         
            DBGLOG("getpeername failed %d",ERRNO());
            ep.set(NULL, 0);
        }
        else
            getSockAddrEndpoint(u,ul,ep);
    }
    return ep;
}

IpAddress & CSocket::getPeerAddress(IpAddress &addr)
{
    SocketEndpoint ep;
    getPeerEndpoint(ep);
    addr = ep;
    return addr;
}

void CSocket::set_return_addr(int port,const char *retname)
{
    if (!returnep.ipset(retname)) {
        IJSOCK_Exception *e = new SocketException(JSOCKERR_bad_address); // don't use THROWJSOCKEXCEPTION here
        throw e;
    }
    returnep.port = port;
}



void CSocket::cancel_accept()
{
    if (connectionless()) {
        THROWJSOCKEXCEPTION(JSOCKERR_connectionless_socket);
    }
#ifdef SOCKTRACE
    PROGLOG("SOCKTRACE: Cancel accept socket %x %d (%x)", sock, sock, this);
#endif
    if (!in_accept) {
        accept_cancel_state = accept_cancelled;
        errclose();
        return;
    }
    accept_cancel_state = accept_cancel_pending;
    errclose();     // this should cause accept to terminate (not supported on all linux though)
#ifdef _WIN32        
    for (unsigned i=0;i<5;i++) { // windows closes on different lower priority thread
        Sleep(i);
        if (accept_cancel_state==accept_cancelled) 
            return;
    }
#else
    Sleep(0);
    if (accept_cancel_state==accept_cancelled) 
        return;
#endif
    // Wakeup listener using a connection
    SocketEndpoint ep(hostport,queryHostIP());
    Owned<CSocket> sock = new CSocket(ep,sm_tcp,NULL);
    try {
        sock->connect_timeout(100,true);
    }
    catch (IJSOCK_Exception *e) { 
        EXCLOG(e,"CSocket::cancel_eccept");
        e->Release();                           
    }
}


// ================================================================================
// connect versions

ISocket*  ISocket::connect( const SocketEndpoint &ep )
{
    // general connect 
    return ISocket::connect_wait(ep,DEFAULT_CONNECT_TIME);
}

inline void refused_sleep(CTimeMon &tm, unsigned &refuseddelay)
{
    unsigned remaining;
    if (!tm.timedout(&remaining)) {
        if (refuseddelay<remaining/4) {
            Sleep(refuseddelay);
            if (refuseddelay<CONNECT_TIMEOUT_REFUSED_WAIT/2)
                refuseddelay *=2;
            else
                refuseddelay = CONNECT_TIMEOUT_REFUSED_WAIT;
        }
        else 
            Sleep(remaining/4); // towards end of timeout approach gradually
    }
}

bool CSocket::connect_timeout( unsigned timeout, bool noexception)
{
    // simple connect with timeout (no fancy stuff!)
    unsigned startt = usTick();
    CTimeMon tm(timeout);
    unsigned remaining;
    unsigned refuseddelay = 1;
    int err;
    while (!tm.timedout(&remaining)) {
        err = pre_connect(false);
        if ((err == EINPROGRESS)||(err == EWOULDBLOCK)) {
            T_FD_SET fds;
            struct timeval tv;
            XFD_ZERO(&fds);
            FD_SET((unsigned)sock, &fds);
            T_FD_SET except;
            XFD_ZERO(&except);
            FD_SET((unsigned)sock, &except);
            tv.tv_sec = remaining / 1000;
            tv.tv_usec = (remaining % 1000)*1000;
            CHECKSOCKRANGE(sock);
            int rc = ::select( sock + 1, NULL, (fd_set *)&fds, (fd_set *)&except, &tv );
            if (rc>0) {
                // select succeeded - return error from socket (0 if connected)
                socklen_t errlen = sizeof(err);
                rc = getsockopt(sock, SOL_SOCKET, SO_ERROR, (char *)&err, &errlen); // check for error
                if ((rc!=0)&&!err) 
                    err = ERRNO();  // some implementations of getsockopt duff
                if (err) //  probably ECONNREFUSED but treat all errors same
                    refused_sleep(tm,refuseddelay);
            }
            else if (rc<0) { 
                err = ERRNO();
                LOGERR2(err,2,"::select");
            }
        }
        if (err==0) {
            err = post_connect();
            if (err==0) {
                STATS.connects++;
                STATS.connecttime+=usTick()-startt;
#ifdef _TRACE
                char peer[256];
                peer[0] = 'C';
                peer[1] = '!';
                strcpy(peer+2,hostname?hostname:"(NULL)");
                free(tracename);
                tracename = strdup(peer);
#endif              
                return true;
            }
        }
        errclose();
    }
#ifdef SOCKTRACE
    PROGLOG("connect_timeout: failed %d",err);
#endif
    STATS.failedconnects++;
    STATS.failedconnecttime+=usTick()-startt;
    if (!noexception)
        THROWJSOCKEXCEPTION(JSOCKERR_connection_failed);
    return false;
}


ISocket*  ISocket::connect_timeout(const SocketEndpoint &ep,unsigned timeout)
{
    if (ep.isNull()||(ep.port==0))
        THROWJSOCKEXCEPTION2(JSOCKERR_bad_address);
    Owned<CSocket> sock = new CSocket(ep,sm_tcp,NULL);
    sock->connect_timeout(timeout,false);
    return sock.getClear();
}

#define POLLTIME 50



void CSocket::connect_wait(unsigned timems)
{
    // simple connect with timeout (no fancy stuff!)
    unsigned startt = usTick();
    CTimeMon tm(timems);
    bool exit = false;
    int err;
    unsigned refuseddelay = 1;
    while (!exit) {
#ifdef CENTRAL_NODE_RANDOM_DELAY
        ForEachItemIn(cn,CentralNodeArray) {
            SocketEndpoint &ep=CentralNodeArray.item(cn);
            if (ep.ipequals(targetip)) {
                unsigned sleeptime = getRandom() % 1000;
                StringBuffer s;
                ep.getIpText(s);
                PrintLog("Connection to central node %s - sleeping %d milliseconds", s.str(), sleeptime);
                Sleep(sleeptime);           
                break;
            }
        }
#endif
        unsigned remaining;
        exit = tm.timedout(&remaining);
        bool blockselect = exit;                            // if last time round block
        {
            CriticalBlock block(crit);
            if (++connectingcount>4)
                blockselect = true;
        }
        err = pre_connect(blockselect);             
        if (blockselect) {
            if (err&&!exit)
                refused_sleep(tm,refuseddelay); //  probably ECONNREFUSED but treat all errors same
        }
        else {
            unsigned timeoutms = (exit||(remaining<10000))?10000:remaining;
            unsigned polltime = 1;
            while (!blockselect && ((err == EINPROGRESS)||(err == EWOULDBLOCK))) {
                T_FD_SET fds;
                struct timeval tv;
                XFD_ZERO(&fds);
                FD_SET((unsigned)sock, &fds);
                T_FD_SET except;
                XFD_ZERO(&except);
                FD_SET((unsigned)sock, &except);
    #ifdef BLOCK_POLLED_SINGLE_CONNECTS         
                tv.tv_sec = timeoutms / 1000;
                tv.tv_usec = (timeoutms % 1000)*1000;
    #else
                tv.tv_sec = 0;
                tv.tv_usec = 0;
    #endif
                CHECKSOCKRANGE(sock);
                int rc = ::select( sock + 1, NULL, (fd_set *)&fds, (fd_set *)&except, &tv );
                if (rc>0) {
                    // select succeeded - return error from socket (0 if connected)
                    socklen_t errlen = sizeof(err);
                    rc = getsockopt(sock, SOL_SOCKET, SO_ERROR, (char *)&err, &errlen); // check for error
                    if ((rc!=0)&&!err)
                        err = ERRNO();  // some implementations of getsockopt duff
                    if (err)
                        refused_sleep(tm,refuseddelay); //  probably ECONNREFUSED but treat all errors same
                    break;
                }
                if (rc<0) { 
                    err = ERRNO();
                    LOGERR2(err,2,"::select");
                    break;
                }
                if (!timeoutms) {
    #ifdef SOCKTRACE
                    PROGLOG("connecttimeout: timed out");
    #endif
                    err = -1;
                    break;
                }
    #ifdef BLOCK_POLLED_SINGLE_CONNECTS 
                break;
    #else
                if (timeoutms<polltime)
                    polltime = timeoutms;
                Sleep(polltime);                    // sleeps 1-50ms (to let other threads run)
                timeoutms -= polltime;
                if (polltime>POLLTIME/2)
                    polltime = POLLTIME;
                else
                    polltime *= 2;
    #endif
            }
        }
        {
            CriticalBlock block(crit);
            --connectingcount;
        }
        if (err==0) {
            err = post_connect();
            if (err==0) {
                STATS.connects++;
                STATS.connecttime+=usTick()-startt;
#ifdef _TRACE
                char peer[256];
                peer[0] = 'C';
                peer[1] = '!';
                strcpy(peer+2,hostname?hostname:"(NULL)");
                free(tracename);
                tracename = strdup(peer);
#endif              
                return;
            }
        }
        errclose();
    }
#ifdef SOCKTRACE
    PROGLOG("connect_wait: failed %d",err);
#endif
    STATS.failedconnects++;
    STATS.failedconnecttime+=usTick()-startt;
    THROWJSOCKEXCEPTION(JSOCKERR_connection_failed);
}



ISocket*  ISocket::connect_wait( const SocketEndpoint &ep, unsigned timems)
{
    if (ep.isNull()||(ep.port==0))
        THROWJSOCKEXCEPTION2(JSOCKERR_bad_address);
    Owned<CSocket> sock = new CSocket(ep,sm_tcp,NULL);
    sock->connect_wait(timems);
    return sock.getClear();
}



void CSocket::udpconnect()
{
    DEFINE_SOCKADDR(u);
    if (targetip.isNull()) {
        set_return_addr(hostport,hostname);
        targetip.ipset(returnep);
    }
    socklen_t  ul = setSockAddr(u,targetip,hostport);
    sock = ::socket(u.sa.sa_family, SOCK_DGRAM, targetip.isIp4()?0:PF_INET6);
#ifdef SOCKTRACE
    PROGLOG("SOCKTRACE: udp connected socket %x %d (%x)", sock, sock, this);
#endif
    STATS.activesockets++;
    if (sock == INVALID_SOCKET) {
        THROWJSOCKEXCEPTION(ERRNO());
    }
    int res = ::connect(sock, &u.sa, ul);
    if (res != 0) { // works for UDP
        closesock();
        THROWJSOCKEXCEPTION(JSOCKERR_connection_failed);
    }
    nagling = false; // means nothing for UDP
    state = ss_open;
#ifdef _TRACE
    char peer[256];
    peer[0] = 'C';
    peer[1] = '!';
    strcpy(peer+2,hostname?hostname:"(NULL)");
    free(tracename);
    tracename = strdup(peer);
#endif

}




int CSocket::wait_read(unsigned timeout)
{
    int ret = 0;
    while (sock!=INVALID_SOCKET) {
        T_FD_SET fds;
        XFD_ZERO(&fds);
        FD_SET((unsigned)sock, &fds);
        CHECKSOCKRANGE(sock);
        if (timeout==WAIT_FOREVER) {
            ret = ::select( sock + 1, (fd_set *)&fds, NULL, NULL, NULL );
        }
        else {
            struct timeval tv;
            tv.tv_sec = timeout / 1000;
            tv.tv_usec = (timeout % 1000)*1000;
            ret = ::select( sock + 1, (fd_set *)&fds, NULL, NULL, &tv );
        }
        if (ret==SOCKET_ERROR) {
            int err = ERRNO();
            if (err!=EINTRCALL) {   // else retry (should adjust time but for our usage don't think it matters that much)
                LOGERR2(err,1,"wait_read");
                break;
            }
        }
        else
            break;
    }
    return ret;
}

int CSocket::wait_write(unsigned timeout)
{
    int ret = 0;
    while (sock!=INVALID_SOCKET) {
        T_FD_SET fds;
        XFD_ZERO(&fds);
        FD_SET((unsigned)sock, &fds);
        CHECKSOCKRANGE(sock);
        if (timeout==WAIT_FOREVER) {
            ret = ::select( sock + 1, NULL, (fd_set *)&fds, NULL, NULL );
        }
        else {
            struct timeval tv;
            tv.tv_sec = timeout / 1000;
            tv.tv_usec = (timeout % 1000)*1000;
            ret = ::select( sock + 1, NULL, (fd_set *)&fds, NULL, &tv );
        }
        if (ret==SOCKET_ERROR) {
            int err = ERRNO();
            if (err!=EINTRCALL) {   // else retry (should adjust time but for our usage don't think it matters that much)
                LOGERR2(err,1,"wait_write");
                break;
            }
        }
        else
            break;
    }
    return ret;
}

void CSocket::readtms(void* buf, size32_t min_size, size32_t max_size, size32_t &size_read,
                     unsigned timeoutms)
{
    if (timeoutms == WAIT_FOREVER) {
        read(buf,min_size, max_size, size_read,WAIT_FOREVER);
        return;
    }
        

    unsigned startt=usTick();
    size_read = 0;
    if (state != ss_open) {
        THROWJSOCKEXCEPTION(JSOCKERR_not_opened);
    }
    unsigned start;
    unsigned timeleft;
    start = msTick();
    timeleft = timeoutms;

    do {
        int rc = wait_read(timeleft);
        if (rc < 0) {
            THROWJSOCKEXCEPTION(ERRNO());
        }
        if (rc == 0) {
            THROWJSOCKEXCEPTION(JSOCKERR_timeout_expired);
        }
        unsigned elapsed = (msTick()-start);
        if (elapsed<timeoutms)
            timeleft = timeoutms-elapsed;
        else
            timeleft = 0;
        unsigned retrycount=100;
EintrRetry:
        if (sockmode==sm_udp_server) { // udp server        
            DEFINE_SOCKADDR(u);
            socklen_t ul=sizeof(u);
            rc = recvfrom(sock, (char*)buf + size_read, max_size - size_read, 0, &u.sa,&ul);
            getSockAddrEndpoint(u,ul,returnep);
        }
        else {
            rc = recv(sock, (char*)buf + size_read, max_size - size_read, 0);
        }
        if (rc < 0) {
            int err = ERRNO();
            if (BADSOCKERR(err)) {
                // don't think this should happen but convert to same as shutdown while investigation
                LOGERR2(err,1,"Socket closed during read");
                rc = 0;
            }
            else if ((err==EINTRCALL)&&(retrycount--!=0)) {
                LOGERR2(err,1,"EINTR retrying");
                goto EintrRetry;
            }
            else {
                LOGERR2(err,1,"readtms");
                if ((err==ECONNRESET)||(err==EINTRCALL)||(err==ECONNABORTED)) {
                    errclose();
                    err = JSOCKERR_broken_pipe;
                }
                THROWJSOCKEXCEPTION(err);
            }
        }
        if (rc == 0) {
            state = ss_shutdown;
            if (min_size==0) 
                break;                      // if min_read is 0 return 0 if socket closed
            THROWJSOCKEXCEPTION(JSOCKERR_graceful_close);
        }
        size_read += rc;
    } while (size_read < min_size);
    STATS.reads++;
    STATS.readsize += size_read;
    STATS.readtime+=usTick()-startt;

}

void CSocket::read(void* buf, size32_t min_size, size32_t max_size, size32_t &size_read,
                     unsigned timeoutsecs)
{
    unsigned startt=usTick();
    size_read = 0;
    unsigned start;
    unsigned timeleft;
    if (state != ss_open) {
        THROWJSOCKEXCEPTION(JSOCKERR_not_opened);
    }
    if (timeoutsecs != WAIT_FOREVER) {
        start = (unsigned)time(NULL);
        timeleft = timeoutsecs;
    }

    do {
        int rc;
        if (timeoutsecs != WAIT_FOREVER) {
            rc = wait_read(timeleft*1000);
            if (rc < 0) {
                THROWJSOCKEXCEPTION(ERRNO());
            }
            if (rc == 0) {
                THROWJSOCKEXCEPTION(JSOCKERR_timeout_expired);
            }
            unsigned elapsed = ((unsigned)time(NULL))-start;
            if (elapsed<timeoutsecs)
                timeleft = timeoutsecs-elapsed;
            else
                timeleft = 0;
        }
        unsigned retrycount=100;
EintrRetry:
        if (sockmode==sm_udp_server) { // udp server
            DEFINE_SOCKADDR(u);
            socklen_t ul=sizeof(u.sin);     
            rc = recvfrom(sock, (char*)buf + size_read, max_size - size_read, 0, &u.sa,&ul);
            getSockAddrEndpoint(u,ul,returnep);
        }
        else {
            rc = recv(sock, (char*)buf + size_read, max_size - size_read, 0);
        }
        if (rc < 0) {
            int err = ERRNO();
            if (BADSOCKERR(err)) {
                // don't think this should happen but convert to same as shutdown while investigation
                LOGERR2(err,3,"Socket closed during read");
                rc = 0;
            }
            else if ((err==EINTRCALL)&&(retrycount--!=0)) {
                if (sock==INVALID_SOCKET)
                    rc = 0;         // convert an EINTR after closed to a graceful close
                else {
                    LOGERR2(err,3,"EINTR retrying");
                    goto EintrRetry;
                }
            }
            else {
                LOGERR2(err,3,"read");
                if ((err==ECONNRESET)||(err==EINTRCALL)||(err==ECONNABORTED)) {
                    errclose();
                    err = JSOCKERR_broken_pipe;
                }
                THROWJSOCKEXCEPTION(err);
            }
        }
        if (rc == 0) {
            state = ss_shutdown;
            if (min_size==0) 
                break;                      // if min_read is 0 return 0 if socket closed
            THROWJSOCKEXCEPTION(JSOCKERR_graceful_close);
        }
        size_read += rc;
    } while (size_read < min_size);
    STATS.reads++;
    STATS.readsize += size_read;
    STATS.readtime+=usTick()-startt;
}

void CSocket::read(void* buf, size32_t size)
{
    if (!size)
        return;
    unsigned startt=usTick();
    size32_t size_read=size;
    if (state != ss_open) {
        THROWJSOCKEXCEPTION(JSOCKERR_not_opened);
    }

    do {
        unsigned retrycount=100;
EintrRetry:
        int rc;
        if (sockmode==sm_udp_server) { // udp server
            DEFINE_SOCKADDR(u);
            socklen_t ul=sizeof(u.sin);
            rc = recvfrom(sock, (char*)buf, size, 0, &u.sa,&ul);
            getSockAddrEndpoint(u,ul,returnep);
        }
        else {
            rc = recv(sock, (char*)buf, size, 0);
        }
        if (rc < 0) {
            int err = ERRNO();
            if (BADSOCKERR(err)) {
                // don't think this should happen but convert to same as shutdown while investigation
                LOGERR2(err,5,"Socket closed during read");
                rc = 0;
            }
            else if ((err==EINTRCALL)&&(retrycount--!=0)) {
                LOGERR2(err,5,"EINTR retrying");
                goto EintrRetry;
            }
            else {
                LOGERR2(err,5,"read");
                if ((err==ECONNRESET)||(err==EINTRCALL)||(err==ECONNABORTED)) {
                    errclose();
                    err = JSOCKERR_broken_pipe;
                }
                THROWJSOCKEXCEPTION(err);
            }
        }
        if (rc == 0) {
            state = ss_shutdown;
            THROWJSOCKEXCEPTION(JSOCKERR_graceful_close);
        }
        buf = (char*)buf + rc;
        size -= rc;
    } while (size != 0);
    STATS.reads++;
    STATS.readsize += size_read;
    STATS.readtime+=usTick()-startt;

}



size32_t CSocket::write(void const* buf, size32_t size)
{
    if (size==0)
        return 0;
    unsigned startt=usTick();
    size32_t size_writ = size;
    if (state != ss_open) {
        THROWJSOCKEXCEPTION(JSOCKERR_not_opened);
    }
    size32_t res=0;
    do {
        unsigned retrycount=100;
EintrRetry:
        int rc;
        if (sockmode==sm_udp_server) { // udp server
            DEFINE_SOCKADDR(u);
            socklen_t  ul = setSockAddr(u,returnep,returnep.port);
            rc = sendto(sock, (char*)buf, size, 0, &u.sa, ul);
        }
        else {
            rc = send(sock, (char*)buf, size, SEND_FLAGS);
        }
        if (rc < 0) {
            int err=ERRNO();
            if (BADSOCKERR(err)) {
                LOGERR2(err,7,"Socket closed during write");
                rc = 0;
            }
            else if ((err==EINTRCALL)&&(retrycount--!=0)) {
                LOGERR2(err,7,"EINTR retrying");
                goto EintrRetry;
            }
            else {
                if (((sockmode==sm_multicast)||(sockmode==sm_udp))&&(err==ECONNREFUSED))
                    break; // ignore
                LOGERR2(err,7,"write");
                if ((err==ECONNRESET)||(err==EINTRCALL)||(err==ECONNABORTED)
#ifndef _WIN32
                    ||(err==EPIPE)||(err==ETIMEDOUT)  // linux can raise these on broken pipe
#endif
                    ) {
                    errclose();
                    err = JSOCKERR_broken_pipe;
                }
                if ((err == EWOULDBLOCK) && nonblocking)
                    break;
                THROWJSOCKEXCEPTION(err);
            }
        }   
        res += rc;
        if (rc == 0) {
            state = ss_shutdown;
            THROWJSOCKEXCEPTION(JSOCKERR_graceful_close);
        }
        if (nonblocking)
            break;
        buf = (char*)buf + rc;
        size -= rc;
    } while (size != 0);
    STATS.writes++;
    STATS.writesize += size_writ;
    STATS.writetime+=usTick()-startt;
    return res;
}

bool CSocket::check_connection()
{
    if (state != ss_open) 
        return false;

    unsigned retrycount=100;
EintrRetry:
    int rc;
    if (sockmode==sm_udp_server) { // udp server
        DEFINE_SOCKADDR(u);
        socklen_t  ul = setSockAddr(u,returnep,returnep.port);
        rc = sendto(sock, NULL, 0, 0, &u.sa, ul);
    }
    else {
        rc = send(sock, NULL, 0, SEND_FLAGS);
    }
    if (rc < 0) {
        int err=ERRNO();
        if ((err==EINTRCALL)&&(retrycount--!=0)) {
            LOGERR2(err,7,"EINTR retrying");
            goto EintrRetry;
        }
        else
            return false;
    }   
    return true;
}

size32_t CSocket::udp_write_to(SocketEndpoint &ep, void const* buf, size32_t size)
{
    if (size==0)
        return 0;
    unsigned startt=usTick();
    size32_t size_writ = size;
    if (state != ss_open) {
        THROWJSOCKEXCEPTION(JSOCKERR_not_opened);
    }
    size32_t res=0;
    DEFINE_SOCKADDR(u); 
    loop {
        socklen_t  ul = setSockAddr(u,ep,ep.port);      
        int rc = sendto(sock, (char*)buf, size, 0, &u.sa, ul);
        if (rc < 0) {
            int err=ERRNO();
            if (((sockmode==sm_multicast)||(sockmode==sm_udp))&&(err==ECONNREFUSED))
                break; // ignore
            if (err!=EINTRCALL) {
                THROWJSOCKEXCEPTION(err);
            }
        }
        else {
            res = (size32_t)rc;
            break;
        }
    }
    STATS.writes++;
    STATS.writesize += res;
    STATS.writetime+=usTick()-startt;
    return res;
}

size32_t CSocket::write_multiple(unsigned num,const void **buf, size32_t *size)
{
    assertex(sockmode!=sm_udp_server);
    assertex(!nonblocking);
    if (num==1)
        return write(buf[0],size[0]);
    size32_t total = 0;
    unsigned i;
    for (i=0;i<num;i++)
        total += size[i];
    if (total==0)
        return 0;
    
    unsigned startt=usTick();
    if (state != ss_open) {
        THROWJSOCKEXCEPTION(JSOCKERR_not_opened);
    }
    size32_t res=0;
#ifdef _WIN32
    WSABUF *bufs = (WSABUF *)alloca(sizeof(WSABUF)*num);
    for (i=0;i<num;i++) {
        bufs[i].buf = (char *)buf[i];
        bufs[i].len = size[i];
    }
    unsigned retrycount=100;
EintrRetry:
    DWORD sent;
    if (WSASendTo(sock,bufs,num,&sent,0,NULL,0,NULL,NULL)==SOCKET_ERROR) {
        int err=ERRNO();
        if (BADSOCKERR(err)) {
            LOGERR2(err,8,"Socket closed during write");
            sent = 0;
        }
        else if ((err==EINTRCALL)&&(retrycount--!=0)) {
            LOGERR2(err,8,"EINTR retrying");
            goto EintrRetry;
        }
        else {
            LOGERR2(err,8,"write_multiple");
            if ((err==ECONNRESET)||(err==EINTRCALL)||(err==ECONNABORTED)||(err==ETIMEDOUT)) {
                errclose();
                err = JSOCKERR_broken_pipe;
            }
            THROWJSOCKEXCEPTION(err);
        }
    }   
    if (sent == 0) {
        state = ss_shutdown;
        THROWJSOCKEXCEPTION(JSOCKERR_graceful_close);
    }
    res = sent;
#else
#ifdef USE_CORK
    if (total>1024) {
        class Copt
        {
            T_SOCKET sock;
            bool nagling;
        public:
            Copt(T_SOCKET _sock,bool _nagling) 
            { 
                nagling = _nagling;
                int enabled = 1;
                int disabled = 0;
                if (!nagling) 
                    setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, (char*)&disabled, sizeof(disabled));
                setsockopt(sock, IPPROTO_TCP, TCP_CORK, (char*)&enabled, sizeof(enabled));
            }
            ~Copt() 
            { 
                int enabled = 1;
                int disabled = 0;
                setsockopt(sock, IPPROTO_TCP, TCP_CORK, (char*)&disabled, sizeof(disabled));
                if (!nagling) 
                    setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, (char*)&enabled, sizeof(enabled));
            }
        } copt(sock,nagling);
        for (i=0;i<num;i++) 
            res += write(buf[i],size[i]);
    }
    else {
        byte b[1024];
        byte *p=b;
        for (i=0;i<num;i++) {
            memcpy(p,buf[i],size[i]);
            p += size[i];
        }
        res = write(b,total);
    }
#else
    // send in equal chunks about 64K
    unsigned n = (total+0xffff)/0x10000;
    size32_t outbufsize = (total+n-1)/n;
    MemoryAttr ma;
    byte *outbuf = (byte *)ma.allocate(outbufsize);
    size32_t outwr = 0;
    i = 0;
    size32_t os = 0;
    size32_t left = total;
    byte *b;
    size32_t s=0;
    loop {
        while (!s&&(i<num)) {
            b = (byte *)buf[i];
            s = size[i];
            i++;
        }
        if ((os==0)&&(s==left)) {
            write(b,s);     // go for it
            break;
        }
        else {
            size32_t cpy = outbufsize-os;
            if (cpy>s)
                cpy = s;
            memcpy(outbuf+os,b,cpy);
            os += cpy;
            left =- cpy;
            s -= cpy;
            b += cpy;
            if (left==0)  {
                write(outbuf,os);       
                break;
            }
            else if (os==outbufsize) {
                write(outbuf,os);   
                os = 0;
            }
        }
    }
#endif
#endif
    STATS.writes++;
    STATS.writesize += res;
    STATS.writetime+=usTick()-startt;
    return res;
}



bool CSocket::send_block(const void *blk,size32_t sz)
{
    unsigned startt=usTick();
#ifdef TRACE_SLOW_BLOCK_TRANSFER
    unsigned startt2;
    unsigned startt3;
#endif
    if (blockflags&BF_SYNC_TRANSFER_PULL) {
        size32_t rd;
        bool eof = true;
        readtms(&eof,sizeof(eof),sizeof(eof),rd,blocktimeoutms);
        if (eof)
            return false;
#ifdef TRACE_SLOW_BLOCK_TRANSFER
        startt2=usTick();
#endif
    }
    if (!blk||!sz) {
        sz = 0;
        write(&sz,sizeof(sz));
        try {
            bool reply;
            size32_t rd;
            readtms(&reply,sizeof(reply),sizeof(reply),rd,blocktimeoutms);
        }
        catch (IJSOCK_Exception *e) { 
            if ((e->errorCode()!=JSOCKERR_broken_pipe)&&(e->errorCode()!=JSOCKERR_graceful_close)) 
                EXCLOG(e,"CSocket::send_block");
            e->Release();                           
        }
        return false;
    }
    size32_t rsz=sz;
    _WINREV(rsz);
    write(&rsz,sizeof(rsz));
    if (blockflags&BF_SYNC_TRANSFER_PUSH) {
#ifdef TRACE_SLOW_BLOCK_TRANSFER
        startt2=usTick();
#endif
        size32_t rd;
        bool eof = true;
        readtms(&eof,sizeof(eof),sizeof(eof),rd,blocktimeoutms);
        if (eof)
            return false;
#ifdef TRACE_SLOW_BLOCK_TRANSFER
        startt3=usTick();
#endif
    }
    write(blk,sz);
    if (blockflags&BF_RELIABLE_TRANSFER) {
        bool isok=false;
        size32_t rd;
        readtms(&isok,sizeof(isok),sizeof(isok),rd,blocktimeoutms);
        if (!isok)
            return false;
    }
    unsigned nowt = usTick();
    unsigned elapsed = nowt-startt;
    STATS.blocksendtime+=elapsed;
    STATS.numblocksends++;
    STATS.blocksendsize+=sz;
    if (elapsed>STATS.longestblocksend) {
        STATS.longestblocksend = elapsed;
        STATS.longestblocksize = sz;
    }
#ifdef TRACE_SLOW_BLOCK_TRANSFER
    static unsigned lastreporttime=0;
    static unsigned lastexceeded=0;
    if (elapsed>1000000*60) { // over 1min
        unsigned t = msTick();
        if (1) { //((t-lastreporttime>1000*60) || // only report once per min
                 // (elapsed>lastexceeded*2)) {
            lastexceeded = elapsed;
            lastreporttime = t;
            WARNLOG("send_block took %ds to %s  (%d,%d,%d)",elapsed/1000000,tracename,startt2-startt,startt3-startt2,nowt-startt3);
        }
    }
#endif
    return true;
}

#ifdef USERECVSEM

class CSemProtect
{
    Semaphore *sem;
    bool *owned;
public:
    CSemProtect() { clear(); }
    ~CSemProtect() 
    { 
        if (sem&&*owned) {
            *owned = false;
            sem->signal(); 
        }
    }
    void set(Semaphore *_sem,bool *_owned)
    {
        sem = _sem;
        owned = _owned;
    }
    bool wait(Semaphore *_sem,bool *_owned,unsigned timeout) {
        if (!*_owned&&!_sem->wait(timeout))
            return false;
        *_owned = true;
        set(_sem,_owned);
        return true;
    }
    void clear() { sem = NULL; owned = NULL; }
};
#endif

size32_t CSocket::receive_block_size()
{
    // assumed always paired with receive_block
    if (nextblocksize) {
        if (blockflags&BF_SYNC_TRANSFER_PULL) {
            bool eof=false;
            write(&eof,sizeof(eof));
        }
        size32_t rd;
        readtms(&nextblocksize,sizeof(nextblocksize),sizeof(nextblocksize),rd,blocktimeoutms);
        _WINREV(nextblocksize);
        if (nextblocksize==0) { // confirm eof
            try {
                bool confirm=true;
                write(&confirm,sizeof(confirm));
            }
            catch (IJSOCK_Exception *e) { 
                if ((e->errorCode()!=JSOCKERR_broken_pipe)&&(e->errorCode()!=JSOCKERR_graceful_close)) 
                    EXCLOG(e,"receive_block_size");
                e->Release();                           
            }
        }
        else if (blockflags&BF_SYNC_TRANSFER_PUSH) {  // leaves receiveblocksem clear
#ifdef USERECVSEM
            CSemProtect semprot; // this will catch exception in write
            while (!semprot.wait(&receiveblocksem,&receiveblocksemowned,60*1000*5))
                WARNLOG("Receive block stalled");
#endif
            bool eof=false;
            write(&eof,sizeof(eof));
#ifdef USERECVSEM
            semprot.clear();
#endif
        }

    }
    return nextblocksize;
}

    
size32_t CSocket::receive_block(void *blk,size32_t maxsize)
{
#ifdef USERECVSEM
    CSemProtect semprot; // this will catch exceptions
#endif
    size32_t sz = nextblocksize;
    if (sz) {
        if (sz==UINT_MAX) { // need to get size
            if (!blk||!maxsize) {
                if (blockflags&BF_SYNC_TRANSFER_PUSH) { // ignore block size
                    size32_t rd;
                    readtms(&nextblocksize,sizeof(nextblocksize),sizeof(nextblocksize),rd,blocktimeoutms);
                }
                if (blockflags&(BF_SYNC_TRANSFER_PULL|BF_SYNC_TRANSFER_PUSH)) { // signal eof
                    bool eof=true;
                    write(&eof,sizeof(eof));
                    nextblocksize = 0;
                    return 0;
                }
            }
            sz = receive_block_size();
            if (!sz) 
                return 0;
        }
        unsigned startt=usTick();   // include sem block but not initial handshake
#ifdef USERECVSEM
        if (blockflags&BF_SYNC_TRANSFER_PUSH)  // read_block_size sets semaphore
            semprot.set(&receiveblocksem,&receiveblocksemowned);  // this will reset semaphore on exit
#endif
        nextblocksize = UINT_MAX;
        size32_t rd;
        if (sz<=maxsize) {
            readtms(blk,sz,sz,rd,blocktimeoutms);
        }
        else { // truncate
            readtms(blk,maxsize,maxsize,rd,blocktimeoutms);
            sz -= maxsize;
            void *tmp=malloc(sz);
            readtms(tmp,sz,sz,rd,blocktimeoutms);
            free(tmp);
            sz = maxsize;
        }
        if (blockflags&BF_RELIABLE_TRANSFER) {
            bool isok=true;
            write(&isok,sizeof(isok));
        }
        unsigned elapsed = usTick()-startt;
        STATS.blockrecvtime+=elapsed;
        STATS.numblockrecvs++;
        STATS.blockrecvsize+=sz;
    }
    return sz;
}

void CSocket::set_block_mode(unsigned flags, size32_t recsize, unsigned _timeoutms)
{
    blockflags = flags;
    nextblocksize = UINT_MAX;
    blocktimeoutms = _timeoutms?_timeoutms:WAIT_FOREVER;
}



void CSocket::shutdown(unsigned mode)
{
    if (state == ss_open) {
        state = ss_shutdown;
#ifdef SOCKTRACE
        PROGLOG("SOCKTRACE: shutdown(%d) socket %x %d (%x)", mode, sock, sock, this);
#endif
        int rc = ::shutdown(sock, mode);
        if (rc != 0) {
            int err=ERRNO();
            if (err==ENOTCONN) {
                LOGERR2(err,9,"shutdown");
                err = JSOCKERR_broken_pipe;
            }
            THROWJSOCKEXCEPTION(err);
        }
    }
}

void CSocket::errclose()
{
#ifdef USERECVSEM
    if (receiveblocksemowned) {
        receiveblocksemowned = false;
        receiveblocksem.signal();
    }
#endif
    if (state != ss_close) {
        state = ss_close;
#ifdef SOCKTRACE
        PROGLOG("SOCKTRACE: errclose socket %x %d (%x)", sock, sock, this);
#endif
        if (mcastreq)
            setsockopt(sock, IPPROTO_IP, IP_DROP_MEMBERSHIP,(char*)mcastreq,sizeof(*mcastreq));
        closesock();
    }
}


void CSocket::close()
{
#ifdef USERECVSEM
    if (receiveblocksemowned) {
        receiveblocksemowned = false;
        receiveblocksem.signal();
    }
#endif
    if (state != ss_close) {
#ifdef SOCKTRACE
        PROGLOG("SOCKTRACE: close socket %x %d (%x)", sock, sock, this);
#endif
        state = ss_close;
        if (mcastreq)
            setsockopt(sock, IPPROTO_IP, IP_DROP_MEMBERSHIP,(char*)mcastreq,sizeof(*mcastreq));
        if (closesock() != 0) {
            THROWJSOCKEXCEPTION(ERRNO());
        }
    }
}

size32_t CSocket::get_max_send_size()
{
    size32_t maxsend=0;
    socklen_t size = sizeof(maxsend);
#if _WIN32
    getsockopt(sock, SOL_SOCKET, SO_MAX_MSG_SIZE, (char *) &maxsend, &size);
#else
    getsockopt(sock, SOL_SOCKET, SO_SNDBUF, (char *) &maxsend, &size);  // not the same but closest I can find
#endif
  return maxsend;
}


size32_t CSocket::get_send_buffer_size()
{
    size32_t maxsend=0;
    socklen_t size = sizeof(maxsend);
    getsockopt(sock, SOL_SOCKET, SO_SNDBUF, (char *) &maxsend, &size);  
    return maxsend;
}


void CSocket::set_send_buffer_size(size32_t maxsend)
{
    if (setsockopt(sock, SOL_SOCKET, SO_SNDBUF, (char *)&maxsend, sizeof(maxsend))!=0) {
        LOGERR2(ERRNO(),1,"setsockopt(SO_SNDBUF)");
    }
#ifdef CHECKBUFSIZE
    size32_t v;
    if (getsockopt(sock, SOL_SOCKET, SO_SNDBUF, (char *)&v, sizeof(v))!=0) {
        LOGERR2(ERRNO(),1,"getsockopt(SO_SNDBUF)");
    }
    if (v!=maxsend) 
        WARNLOG("set_send_buffer_size requested %d, got %d",maxsend,v);
#endif
}


size32_t CSocket::get_receive_buffer_size()
{
    size32_t max=0;
    socklen_t size = sizeof(max);
    getsockopt(sock, SOL_SOCKET, SO_RCVBUF, (char *) &max, &size);  
    return max;
}


void CSocket::set_receive_buffer_size(size32_t max)
{
    if (setsockopt(sock, SOL_SOCKET, SO_RCVBUF, (char *)&max, sizeof(max))!=0) {
        LOGERR2(ERRNO(),1,"setsockopt(SO_RCVBUF)");
    }
#ifdef CHECKBUFSIZE
    size32_t v;
    if (getsockopt(sock, SOL_SOCKET, SO_RCVBUF, (char *)&v, sizeof(v))!=0) {
        LOGERR2(ERRNO(),1,"getsockopt(SO_RCVBUF)");
    }
    if (v<max) 
        WARNLOG("set_receive_buffer_size requested %d, got %d",max,v);
#endif
}


bool CSocket::join_multicast_group(SocketEndpoint &ep) 
{
    StringBuffer s;
    ep.getIpText(s);    // will improve later
    MCASTREQ req(s.str());
    if (setsockopt(sock, IPPROTO_IP, IP_ADD_MEMBERSHIP,(char*)&req, sizeof(req))!=0) {
        return false;
    }
    return true;
}


bool CSocket::leave_multicast_group(SocketEndpoint &ep) 
{
    StringBuffer s;
    ep.getIpText(s);    // will improve later
    MCASTREQ req(s.str());
    if (setsockopt(sock, IPPROTO_IP, IP_DROP_MEMBERSHIP,(char*)&req, sizeof(req))!=0) {
        return false;
    }
    return true;
}



CSocket::~CSocket()
{
  if (owned) 
    close();
  free(hostname);
  hostname = NULL;
#ifdef _TRACE
  free(tracename);
  tracename = NULL;
#endif
  delete mcastreq;
}

CSocket::CSocket(const SocketEndpoint &ep,SOCKETMODE smode,const char *name)
{
    state = ss_close;
    nonblocking = false;
#ifdef USERECVSEM
    receiveblocksemowned = false;
#endif
    nagling = true; // until turned off
    hostport = ep.port;
    hostname = NULL;
    mcastreq = NULL;
    tracename = NULL;
    StringBuffer tmp;
    if ((smode==sm_multicast_server)&&(name&&*name)) {
        mcastreq = new MCASTREQ(name);
    }
    else {
        if (!name&&!ep.isNull())
            name = ep.getIpText(tmp).str();
        hostname = name?strdup(name):NULL;
    }
    sock = INVALID_SOCKET;
    sockmode = smode;
    owned = true;
    nextblocksize = 0;
    in_accept = false;
    accept_cancel_state = accept_not_cancelled;
#ifdef _TRACE
    char peer[256];
    peer[0] = name?'T':'S';
    peer[1] = '>';
    if (name)
        strcpy(peer+2,name);
    else {
        SocketEndpoint self;
        self.setLocalHost(0);
        self.getUrlStr(peer+2,sizeof(peer)-2);
    }
    tracename = strdup(peer);
#endif
}

CSocket::CSocket(T_SOCKET new_sock,SOCKETMODE smode,bool _owned)
{
    nonblocking = false;
#ifdef USERECVSEM
    receiveblocksemowned = false;
#endif
    nagling = true; // until turned off
    sock = new_sock;
    if (new_sock!=INVALID_SOCKET)
        STATS.activesockets++;
    hostname = NULL;
    mcastreq = NULL;
    hostport = 0;
    tracename = NULL;
    state = ss_open;
    sockmode = smode;
    owned = _owned;
    nextblocksize = 0;
    in_accept = false;
    accept_cancel_state = accept_not_cancelled;
    set_nagle(false);
    //set_linger(DEFAULT_LINGER_TIME); -- experiment with removing this as closesocket should still endevour to send outstanding data
#ifdef _TRACE
    char peer[256];
    peer[0] = 'A';
    peer[1] = '!';
    peer_name(peer+2,sizeof(peer)-2);
    tracename = strdup(peer);
#endif
}

ISocket* ISocket::create(unsigned short p,int listen_queue_size)
{
    if (p==0)
        THROWJSOCKEXCEPTION2(JSOCKERR_bad_address);
    SocketEndpoint ep;
    ep.port = p;
    Owned<CSocket> sock = new CSocket(ep,sm_tcp_server,NULL);
    sock->open(listen_queue_size);
    return sock.getClear();
}


ISocket* ISocket::create_ip(unsigned short p,const char *host,int listen_queue_size)
{
    if (p==0)
        THROWJSOCKEXCEPTION2(JSOCKERR_bad_address);
    SocketEndpoint ep(host,p);
    Owned<CSocket> sock = new CSocket(ep,sm_tcp_server,host);
    sock->open(listen_queue_size);
    return sock.getClear();
}


ISocket* ISocket::udp_create(unsigned short p)
{
    SocketEndpoint ep;
    ep.port=p;
    Owned<CSocket> sock = new CSocket(ep,(p==0)?sm_udp:sm_udp_server,NULL);
    sock->open(0);
    return sock.getClear();
}

ISocket* ISocket::multicast_create(unsigned short p, const char *mcip)
{
    if (p==0)
        THROWJSOCKEXCEPTION2(JSOCKERR_bad_address);
    SocketEndpoint ep(mcip,p);
    Owned<CSocket> sock = new CSocket(ep,sm_multicast_server,mcip);
    sock->open(0,true);
    return sock.getClear();
}

ISocket* ISocket::multicast_create(unsigned short p, const IpAddress &ip)
{
    if (p==0)
        THROWJSOCKEXCEPTION2(JSOCKERR_bad_address);
    SocketEndpoint ep(p, ip);
    StringBuffer tmp;
    Owned<CSocket> sock = new CSocket(ep,sm_multicast_server,ip.getIpText(tmp).str());
    sock->open(0,true);
    return sock.getClear();
}

ISocket* ISocket::udp_connect(unsigned short p, char const* name)
{
    if (!name||!*name||(p==0))
        THROWJSOCKEXCEPTION2(JSOCKERR_bad_address);
    SocketEndpoint ep(name, p);
    Owned<CSocket> sock = new CSocket(ep,sm_udp,name);
    sock->udpconnect();
    return sock.getClear();
}

ISocket* ISocket::udp_connect(const SocketEndpoint &ep)
{
    Owned<CSocket> sock = new CSocket(ep,sm_udp,NULL);
    sock->udpconnect();
    return sock.getClear();
}

ISocket* ISocket::multicast_connect(unsigned short p, char const* mcip, unsigned _ttl)
{
    if (p==0)
        THROWJSOCKEXCEPTION2(JSOCKERR_bad_address);
    SocketEndpoint ep(mcip,p);
    return multicast_connect(ep, _ttl);
}

ISocket* ISocket::multicast_connect(const SocketEndpoint &ep, unsigned _ttl)
{
    Owned<CSocket> sock = new CSocket(ep,sm_multicast,NULL);
    sock->udpconnect();
    u_char ttl = _ttl;
    setsockopt(sock->OShandle(), IPPROTO_IP, IP_MULTICAST_TTL, (char *) &ttl, sizeof(ttl));
    return sock.getClear();
}

ISocket* ISocket::attach(int s, bool tcpip)
{
    CSocket* sock = new CSocket((SOCKET)s, tcpip?sm_tcp:sm_udp, false);
    return sock;
}

bool isInterfaceIp(const IpAddress &ip, const char *ifname)
{
#ifdef _WIN32
    return false;
#else
    int fd = socket(AF_INET, SOCK_DGRAM, 0);  // IPV6 TBD
    if (fd<0)
        return false;
    MemoryAttr ma;
    char *buf = (char *)ma.allocate(1024); 
    struct ifconf ifc;
    ifc.ifc_len = 1024;
    ifc.ifc_buf = buf;
    if(ioctl(fd, SIOCGIFCONF, &ifc) < 0) // query interfaces
        return false;
    struct ifreq *ifr = ifc.ifc_req;
    unsigned n = ifc.ifc_len/sizeof(struct ifreq);
    bool match = false;
    for(unsigned i=0; i<n; i++)
    {
        struct ifreq *item = &ifr[i];
        if (ifname&&*ifname)
            if (!WildMatch(item->ifr_name,ifname))
                continue;
        IpAddress iptest((inet_ntoa(((struct sockaddr_in *)&item->ifr_addr)->sin_addr)));
        if (ip.ipequals(iptest))
        {
            match = true;
            break;
        }
    }
    close(fd);
    return match;
#endif
}

bool getInterfaceIp(IpAddress &ip,const char *ifname)
{
#ifdef _WIN32
    return false;
#else
    ip.ipset(NULL);
    int fd = socket(AF_INET, SOCK_DGRAM, 0);  // IPV6 TBD
    if (fd<0)
        return false;
    MemoryAttr ma;
    char *buf = (char *)ma.allocate(1024);
    struct ifconf ifc;
    ifc.ifc_len = 1024;
    ifc.ifc_buf = buf;
    if(ioctl(fd, SIOCGIFCONF, &ifc) < 0) // query interfaces
        return false;
    struct ifreq *ifr = ifc.ifc_req;
    unsigned n = ifc.ifc_len/sizeof(struct ifreq);
    for (int loopback = 0; loopback <= 1; loopback++)
    {
        for (int i=0; i<n; i++)
        {
            bool useLoopback = (loopback==1);
            struct ifreq *item = &ifr[i];
            if (ifname&&*ifname)
                if (!WildMatch(item->ifr_name,ifname))
                    continue;
            IpAddress iptest((inet_ntoa(((struct sockaddr_in *)&item->ifr_addr)->sin_addr)));
            if (iptest.isLoopBack() == useLoopback)
            {
                if (ip.isNull())
                    ip.ipset(iptest);
                else if (!PreferredSubnet.isNull()&&!PreferredSubnet.test(ip)&&PreferredSubnet.test(iptest))
                    ip.ipset(iptest);
            }
        }
        if (!ip.isNull())
            break;
    }
    close(fd);
    return !ip.isNull();
#endif
}


static StringAttr cachehostname;
static IpAddress cachehostip;
static IpAddress localhostip;
static CriticalSection hostnamesect;
static StringBuffer EnvConfPath;

const char * GetCachedHostName()
{
    CriticalBlock c(hostnamesect);
    if (!cachehostname.get())
    {
#ifndef _WIN32
        IpAddress ip;
        if (EnvConfPath.length() == 0)
            EnvConfPath.append(CONFIG_DIR).append(PATHSEPSTR).append("environment.conf");
        Owned<IProperties> conf = createProperties(EnvConfPath.str(), true);

        StringBuffer ifs;
        conf->getProp("interface", ifs);
        if (getInterfaceIp(ip, ifs.str()))
        {
            StringBuffer ips;
            ip.getIpText(ips);
            if (ips.length())
            {
                cachehostname.set(ips.str());
                cachehostip.ipset(ip);
                return cachehostname.get();
            }
        }
#endif
        char temp[1024];
        if (gethostname(temp, sizeof(temp))==0)
            cachehostname.set(temp);                
        else
            cachehostname.set("localhost");         // assume no NIC card
    }
    return cachehostname.get();
}


IpAddress & queryLocalIP()
{
    CriticalBlock c(hostnamesect);
    if (localhostip.isNull()) 
        if (IP6preferred)
            localhostip.ipset("::1");   //IPv6 
        else
            localhostip.ipset("127.0.0.1"); //IPv4
    return localhostip;
}

IpAddress & queryHostIP()
{
    CriticalBlock c(hostnamesect);
    if (cachehostip.isNull()) {
        if (!cachehostip.ipset(GetCachedHostName())) {
            cachehostip.ipset(queryLocalIP());          
            printf("hostname %s not resolved, using localhost\n",GetCachedHostName()); // don't use jlog in case recursive
        }
    }
    return cachehostip;
}

IpAddress &GetHostIp(IpAddress &ip)
{
    ip.ipset(queryHostIP());
    return ip;
}

IpAddress &localHostToNIC(IpAddress &ip)
{
    if (ip.isLoopBack())
        GetHostIp(ip);
    return ip;
}

// IpAddress


inline bool isIp4(const unsigned *netaddr)
{
    if (IP4only)
        return true;
    if (netaddr[2]==0xffff0000)
        return (netaddr[1]==0)&&(netaddr[0]==0);
    if (netaddr[2]==0)
        if ((netaddr[3]==0)&&(netaddr[0]==0)&&(netaddr[1]==0))
            return true; // null address
    // maybe should get loopback here
    return false;
}

bool IpAddress::isIp4() const
{
    return ::isIp4(netaddr);
}

bool IpAddress::isNull() const
{
    return (netaddr[3]==0)&&(IP4only||((netaddr[2]==0)&&(netaddr[1]==0)&&(netaddr[0]==0)));
}

bool IpAddress::isLoopBack() const
{
    if (::isIp4(netaddr)&&((netaddr[3] & 0x000000ff)==0x000007f))
        return true;
    return (netaddr[3]==0x1000000)&&(netaddr[2]==0)&&(netaddr[1]==0)&&(netaddr[0]==0);
}

bool IpAddress::isLocal() const 
{ 
    if (isLoopBack() || isHost())
        return true;
    IpAddress ip(*this);
    return isInterfaceIp(ip, NULL);
}

bool IpAddress::ipequals(const IpAddress & other) const
{
    // reverse compare for speed
    return (other.netaddr[3]==netaddr[3])&&(IP4only||((other.netaddr[2]==netaddr[2])&&(other.netaddr[1]==netaddr[1])&&(other.netaddr[0]==netaddr[0])));
}

int  IpAddress::ipcompare(const IpAddress & other) const
{
    return memcmp(&netaddr, &other.netaddr, sizeof(netaddr));
}

unsigned IpAddress::iphash(unsigned prev) const
{
    return hashc((const byte *)&netaddr,sizeof(netaddr),prev);
}

bool IpAddress::isHost() const
{
    return ipequals(queryHostIP());
}

static bool decodeNumericIP(const char *text,unsigned *netaddr)
{
    if (!text)
        return false;
    bool isv6 = strchr(text,':')!=NULL;
    StringBuffer tmp;
    if ((*text=='[')&&!IP4only) {
        text++;
        size32_t l = strlen(text);
        if ((l<=2)||(text[l-1]!=']'))
            return false;
        text = tmp.append(l-2,text);
    }
    if (!isv6&&isdigit(text[0])) {
        if (_inet_pton(AF_INET, text, &netaddr[3])>0) {
            netaddr[2] = netaddr[3]?0xffff0000:0;  // check for NULL
            netaddr[1] = 0;
            netaddr[0] = 0;         // special handling for loopback?
            return true;
        }
    }
    else if (isv6&&!IP4only) {
        int ret = _inet_pton(AF_INET6, text, netaddr);
        if (ret>=0)
            return (ret>0);
        int err = ERRNO();
        StringBuffer tmp("_inet_pton: ");
        tmp.append(text);
        LOGERR(err,1,tmp.str());
    }   
    return false;
}

static bool lookupHostAddress(const char *name,unsigned *netaddr)
{
    // if IP4only or using MS V6 can only resolve IPv4 using 
    static bool recursioncheck = false; // needed to stop error message recursing
    unsigned retry=10;
#if defined(__linux__) || defined(getaddrinfo)
    if (IP4only) {
#else
    {
#endif
        CriticalBlock c(hostnamesect);
        hostent * entry = gethostbyname(name);
        while (entry==NULL) {
            if (retry--==0) {
                if (!recursioncheck) {
                    recursioncheck = true;
                    LogErr(h_errno,1,"gethostbyname failed",__LINE__,name);
                    recursioncheck = false;
                }
                return false;
            }
            {
                CriticalUnblock ub(hostnamesect);
                Sleep((10-retry)*100);
            }
            entry = gethostbyname(name);
        }
        if (entry->h_addr_list[0]) {
            unsigned ptr = 0;
            if (!PreferredSubnet.isNull()) {
                loop {
                    ptr++;
                    if (entry->h_addr_list[ptr]==NULL) {
                        ptr = 0;
                        break;
                    }
                    IpAddress ip;
                    ip.setNetAddress(sizeof(unsigned),entry->h_addr_list[ptr]);
                    if (PreferredSubnet.test(ip))
                        break;
                }
            }
            memcpy(&netaddr[3], entry->h_addr_list[ptr], sizeof(netaddr[3]));
            netaddr[2] = 0xffff0000;
            netaddr[1] = 0;
            netaddr[0] = 0;
            return true;
        }
        return false;
    }
#if defined(__linux__) || defined(getaddrinfo)
    struct addrinfo hints;
    memset(&hints,0,sizeof(hints));
    struct addrinfo  *addrInfo = NULL;
    loop {
        memset(&hints,0,sizeof(hints));
        int ret = getaddrinfo(name, NULL , &hints, &addrInfo);
        if (!ret) 
            break;
        if (retry--==0) {
            if (!recursioncheck) {
                recursioncheck = true;
                LogErr(ret,1,"getaddrinfo failed",__LINE__,name);
#ifdef _DEBUG
                PrintStackReport();
#endif
                recursioncheck = false;
            }
            return false;
        }
        Sleep((10-retry)*100);
    }
    struct addrinfo  *best = NULL;
    bool snm = !PreferredSubnet.isNull();
    loop {
        struct addrinfo  *ai;
        for (ai = addrInfo; ai; ai = ai->ai_next) {
//          printf("flags=%d, family=%d, socktype=%d, protocol=%d, addrlen=%d, canonname=%s\n",ai->ai_flags,ai->ai_family,ai->ai_socktype,ai->ai_protocol,ai->ai_addrlen,ai->ai_canonname?ai->ai_canonname:"NULL");
            switch (ai->ai_family) {
            case AF_INET: {
                    if (snm) {
                        IpAddress ip;
                        ip.setNetAddress(sizeof(in_addr),&(((sockaddr_in *)ai->ai_addr)->sin_addr));
                        if (!PreferredSubnet.test(ip))
                            continue;
                    }
                    if ((best==NULL)||((best->ai_family==AF_INET6)&&!IP6preferred))
                        best = ai;
                    break;
                }
            case AF_INET6: {
                    if (snm) {
                        IpAddress ip;
                        ip.setNetAddress(sizeof(in_addr6),&(((sockaddr_in6 *)ai->ai_addr)->sin6_addr));
                        if (!PreferredSubnet.test(ip))
                            continue;
                    }
                    if ((best==NULL)||((best->ai_family==AF_INET)&&IP6preferred))
                        best = ai;
                    break;
                }                   
            }
        }
        if (best||!snm)
            break;
        snm = false;
    }
    if (best) {
        if (best->ai_family==AF_INET6)
            memcpy(netaddr,&(((sockaddr_in6 *)best->ai_addr)->sin6_addr),sizeof(netaddr));
        else {
            memcpy(netaddr+3,&(((sockaddr_in *)best->ai_addr)->sin_addr),sizeof(netaddr[3]));
            netaddr[2] = 0xffff0000;
            netaddr[1] = 0;
            netaddr[0] = 0;
        }
    }
    freeaddrinfo(addrInfo);
    return best!=NULL;
#endif
    return false;
            
}



bool IpAddress::ipset(const char *text)
{
    if (text&&*text) {
        if ((text[0]=='.')&&(text[1]==0)) {
            ipset(queryHostIP());
            return true;
        }
        if (decodeNumericIP(text,netaddr))
            return true;
        const char *s;
        for (s=text;*s;s++)
            if (!isdigit(*s)&&(*s!=':')&&(*s!='.')) 
                break;
        if (!*s)
            return ipset(NULL);
        if (lookupHostAddress(text,netaddr))
            return true;
    }
    memset(&netaddr,0,sizeof(netaddr));
    return false;
}

inline char * addbyte(char *s,byte b)
{
    if (b>=100) {
        *(s++) = b/100+'0';
        b %= 100;
        *(s++) = b/10+'0';
        b %= 10;
    }
    else if (b>=10) {
        *(s++) = b/10+'0';
        b %= 10;
    }
    *(s++) = b+'0';
    return s;
}
        


StringBuffer & IpAddress::getIpText(StringBuffer & out) const
{
    if (::isIp4(netaddr)) {
        const byte *ip = (const byte *)&netaddr[3];
        char ips[16]; 
        char *s = ips;
        for (unsigned i=0;i<4;i++) {
            if (i)
                *(s++) = '.';
            s = addbyte(s,ip[i]);
        }
        return out.append(s-ips,ips); 
    }
    char tmp[INET6_ADDRSTRLEN];
    const char *res = _inet_ntop(AF_INET6, &netaddr, tmp, sizeof(tmp));
    if (!res) 
        throw MakeOsException(errno);
    return out.append(res);
}

void IpAddress::ipserialize(MemoryBuffer & out) const
{
    if (((netaddr[2]==0xffff0000)||(netaddr[2]==0))&&(netaddr[1]==0)&&(netaddr[0]==0)) {
        if (netaddr[3]==IPV6_SERIALIZE_PREFIX)
            throw MakeStringException(-1,"Invalid network address"); // hack prevention
        out.append(sizeof(netaddr[3]), &netaddr[3]); 
    }
    else {
        unsigned pfx = IPV6_SERIALIZE_PREFIX;
        out.append(sizeof(pfx),&pfx).append(sizeof(netaddr),&netaddr);
    }
}

void IpAddress::ipdeserialize(MemoryBuffer & in)
{
    unsigned pfx;
    in.read(sizeof(pfx),&pfx);
    if (pfx!=IPV6_SERIALIZE_PREFIX) {
        netaddr[0] = 0;
        netaddr[1] = 0;
        netaddr[2] = (pfx == 0 || pfx == 0x1000000) ? 0 : 0xffff0000; // catch null and loopback
        netaddr[3] = pfx;
    }
    else 
        in.read(sizeof(netaddr),&netaddr);
}


unsigned IpAddress::ipdistance(const IpAddress &other,unsigned offset) const
{   
    if (offset>3)
        offset = 3;
    int i1;
    _cpyrev4(&i1,&netaddr[3-offset]);
    int i2;
    _cpyrev4(&i2,&other.netaddr[3-offset]);
    i1-=i2;
    if (i1>0)
        return i1;
    return -i1;
}

bool IpAddress::ipincrement(unsigned count,byte minoctet,byte maxoctet,unsigned short minipv6piece,unsigned maxipv6piece)
{
    unsigned base;
    if (::isIp4(netaddr)) {
        base = maxoctet-minoctet+1;
        if (!base||(base>256))
            return false;
        byte * ips = (byte *)&netaddr[3];
        byte * ip = ips+4;
        while (count) {
            if (ip==ips)
                return false;   // overflow
            ip--;
            unsigned v = (count+((*ip>minoctet)?(*ip-minoctet):0));
            *ip = minoctet + v%base;
            count = v/base;
        }
    }
    else {
        base = maxipv6piece-minipv6piece+1;
        if (!base||(base>0x10000))
            return false;
        unsigned short * ps = (unsigned short *)&netaddr;
        unsigned short * p = ps+8;
        while (count) {
            if (p==ps)
                return false;   // overflow (actually near impossible!)
            p--;
            unsigned v = (count+((*p>minipv6piece)?(*p-minipv6piece):0));
            *p = minipv6piece + v%base;
            count = v/base;
        }
    }
    return true;
}

unsigned IpAddress::ipsetrange( const char *text)  // e.g. 10.173.72.1-65  ('-' may be omitted)
{
    unsigned e=0;
    unsigned f=0;
    const char *r = strchr(text,'-');   
    bool ok;
    if (r) {
        e = atoi(r+1);
        StringBuffer tmp(r-text,text);
        ok = ipset(tmp.str());
        if (!::isIp4(netaddr))
            IPV6_NOT_IMPLEMENTED();              // TBD IPv6
        if (ok) {
            while ((r!=text)&&(*(r-1)!='.'))
                r--;
            f = (r!=text)?atoi(r):0;    
        }
    }
    else
        ok = ipset(text);
    if ((f>e)||!ok) 
        return 0;
    return e-f+1;
}


size32_t IpAddress::getNetAddress(size32_t maxsz,void *dst) const
{
    if (maxsz==sizeof(unsigned)) {
        if (::isIp4(netaddr)) {
            *(unsigned *)dst = netaddr[3];
            return maxsz;
        }
    }
    else if (!IP4only&&(maxsz==sizeof(netaddr))) {
        memcpy(dst,&netaddr,maxsz);
        return maxsz;
    }
    return 0;
}

void IpAddress::setNetAddress(size32_t sz,const void *src)
{
    if (sz==sizeof(unsigned)) { // IPv4
        netaddr[0] = 0;
        netaddr[1] = 0;
        netaddr[2]=0xffff0000;
        netaddr[3] = *(const unsigned *)src;
    }
    else if (!IP4only&&(sz==sizeof(netaddr))) { // IPv6
        memcpy(&netaddr,src,sz);
        if ((netaddr[2]==0)&&(netaddr[3]!=0)&&(netaddr[3]!=0x1000000)&&(netaddr[0]==0)&&(netaddr[1]==0))
            netaddr[2]=0xffff0000;  // use this form only
    }
    else
        memset(&netaddr,0,sizeof(netaddr));
}


void SocketEndpoint::deserialize(MemoryBuffer & in)
{
    ipdeserialize(in);
    in.read(port);
}

void SocketEndpoint::serialize(MemoryBuffer & out) const
{
    ipserialize(out);
    out.append(port);
}


bool SocketEndpoint::set(const char *name,unsigned short _port)
{ 
    if (name) {
        if (*name=='[') { 
            const char *s = name+1;
            const char *t = strchr(s,']');
            if (t) {
                StringBuffer tmp(t-s,s);
                if (t[1]==':') 
                    _port = atoi(t+2);
                return set(tmp.str(),_port);
            }
        }
        const char * colon = strchr(name, ':');
        if (colon) {
            if (!IP4only&&strchr(colon+1, ':'))
                colon = NULL; // hello its IpV6
        }
        else
            colon = strchr(name, '|'); // strange hole convention
        char ips[260];
        if (colon) {
            size32_t l = colon-name;
            if (l>=sizeof(ips))
                l = sizeof(ips)-1;
            memcpy(ips,name,l);
            ips[l] = 0;
            name = ips;
            _port = atoi(colon+1);
        }
        if (ipset(name)) {
            port = _port; 
            return true;
        }
    }
    ipset(NULL);
    port = 0;   
    return false;
}

void SocketEndpoint::getUrlStr(char * str, size32_t len) const
{
    if (len==0)
        return;
    StringBuffer _str;
    getUrlStr(_str);
    size32_t l = _str.length()+1;
    if (l>len)
    { 
        l = len-1;
        str[l] = 0;
    }
    memcpy(str,_str.toCharArray(),l);
}

StringBuffer &SocketEndpoint::getUrlStr(StringBuffer &str) const
{
    getIpText(str);
    if (port) 
        str.append(':').append((unsigned)port);         // TBD IPv6 put [] on
    return str;
}


unsigned SocketEndpoint::hash(unsigned prev) const
{
    return hashc((const byte *)&port,sizeof(port),iphash(prev));
}




//---------------------------------------------------------------------------

SocketListCreator::SocketListCreator()
{
    lastPort = 0;
}

void SocketListCreator::addSocket(const SocketEndpoint &ep)
{
    StringBuffer ipstr;
    ep.getIpText(ipstr);
    addSocket(ipstr.str(), ep.port);
}

void SocketListCreator::addSocket(const char * ip, unsigned port)
{
    if (fullText.length())
        fullText.append("|");

    const char * prev = lastIp;
    const char * startCopy = ip;
    if (prev)
    {
        if (strcmp(ip, prev) == 0)
        {
            fullText.append("=");
            startCopy = NULL;
        }
        else
        {
            const char * cur = ip;
            loop
            {
                char n = *cur;
                if (!n)
                    break;
                if (n != *prev)
                    break;
                cur++; 
                prev++;
                if (n == '.')
                    startCopy = cur;
            }
            if (startCopy != ip)
                fullText.append("*");
        }
    }

    fullText.append(startCopy);
    if (lastPort != port)
        fullText.append(":").append(port);

    lastIp.set(ip);
    lastPort = port;
}

const char * SocketListCreator::getText()
{
    return fullText.str();
}

void SocketListCreator::addSockets(SocketEndpointArray &array)
{
    ForEachItemIn(i,array) {
        SocketEndpoint &sockep=array.item(i);
        StringBuffer ipstr;
        sockep.getIpText(ipstr);
        addSocket(ipstr.str(),sockep.port);
    }
}


//---------------------------------------------------------------------------

SocketListParser::SocketListParser(const char * text)
{
    fullText.set(text);
    cursor = NULL;
    lastPort = 0;
}

void SocketListParser::first(unsigned port)
{
    cursor = fullText;
    lastIp.set(NULL);
    lastPort = port;
}

bool SocketListParser::get(StringAttr & ip, unsigned & port, unsigned index, unsigned defport)
{
    first(defport);
    do
    {
        if (!next(ip, port))
            return false;
    } while (index--);
    return true;
}

bool SocketListParser::next(StringAttr & ip, unsigned & port)
{
    // IPV6TBD

    StringBuffer ipText;
    if (*cursor == 0)
        return false;
    if (*cursor == '=')
    {
        ipText.append(lastIp);
        cursor++;
    }
    else if (*cursor == '*')
    {
        cursor++;

        //count the number of dots in the tail
        const char * cur = cursor;
        unsigned count = 0;
        loop
        {
            char c = *cur++;
            switch (c)
            {
            case 0:
            case '|':
            case ',':
            case ':':
                goto done;
            case '.':
                ++count;
                break;
            }
        }
done:
        //copy up to the appropriate dot from the previous ip.
        const unsigned dotCount = 3;        //more what about 6 digit ip's
        cur = lastIp;
        loop
        {
            char c = *cur++;
            switch (c)
            {
            case 0:
            case '|':
            case ',':
            case ':':
                assertex(!"Should not get here!");
                goto done2;
            case '.':
                ipText.append(c);
                if (++count == dotCount)
                    goto done2;
                break;
            default:
                ipText.append(c);
                break;
            }
        }
done2:;
    }

    bool inPort = false;
    port = lastPort;
    loop
    {
        char c = *cursor++;
        switch (c)
        {
        case 0:
            cursor--;
            goto doneCopy;
        case '|':
        case ',':
            goto doneCopy;
        case ':':
            port = atoi(cursor);
            inPort = true;
            break;;
        default:
            if (!inPort)
                ipText.append(c);
            break;
        }
    }

doneCopy:
    lastIp.set(ipText.str());
    ip.set(lastIp);
    lastPort = port;
    return true;
}

unsigned SocketListParser::getSockets(SocketEndpointArray &array,unsigned defport)
{
    first(defport);
    StringAttr ip;
    unsigned port;
    while (next(ip,port)) {
        SocketEndpoint ep(ip,port);
        array.append(ep);
    }
    return array.ordinality();
}

void getSocketStatistics(JSocketStatistics &stats)
{
    // should put in simple lock
    memcpy(&stats,&STATS,sizeof(stats));
}

void resetSocketStatistics()
{
    unsigned activesockets=STATS.activesockets;
    memset(&STATS,0,sizeof(STATS));
    STATS.activesockets = activesockets;
}

static StringBuffer &appendtime(StringBuffer &s,unsigned us)
{
    // attemp to get into more sensible units
    if (us>10000000)
        return s.append(us/1000000).append('s');
    if (us>10000)
        return s.append(us/1000).append("ms");
    return s.append(us).append("us");
}


StringBuffer &getSocketStatisticsString(JSocketStatistics &stats,StringBuffer &str)
{

    str.append("connects=").append(stats.connects).append('\n');
    appendtime(str.append("connecttime="),stats.connecttime).append('\n');
    str.append("failedconnects=").append(stats.failedconnects).append('\n');
    appendtime(str.append("failedconnecttime="),stats.failedconnecttime).append('\n');
    str.append("reads=").append(stats.reads).append('\n');
    appendtime(str.append("readtime="),stats.readtime).append('\n');
    str.append("readsize=").append(stats.readsize).append(" bytes\n");
    str.append("writes=").append(stats.writes).append('\n');
    appendtime(str.append("writetime="),stats.writetime).append('\n');
    str.append("writesize=").append(stats.writesize).append(" bytes").append('\n');
    str.append("activesockets=").append(stats.activesockets).append('\n');
    str.append("numblockrecvs=").append(stats.numblockrecvs).append('\n');
    str.append("numblocksends=").append(stats.numblocksends).append('\n');
    str.append("blockrecvsize=").append(stats.blockrecvsize).append('\n');
    str.append("blocksendsize=").append(stats.blocksendsize).append('\n');
    str.append("blockrecvtime=").append(stats.blockrecvtime).append('\n');
    str.append("blocksendtime=").append(stats.blocksendtime).append('\n');
    str.append("longestblocksend=").append(stats.longestblocksend).append('\n');
    str.append("longestblocksize=").append(stats.longestblocksize);
    return str;
}

// ===============================================================================
// select thread for handling multiple selects

struct SelectItem
{
    ISocket *sock;
    T_SOCKET handle;
    ISocketSelectNotify *nfy;
    byte mode;
    bool del;
};

inline SelectItem &Array__Member2Param(SelectItem &src)                 { return src; }
inline void Array__Assign(SelectItem & dest, SelectItem &src)           { dest=src; }
inline bool Array__Equal(SelectItem &m, SelectItem &p)                  { return m.sock==p.sock; }
inline void Array__Destroy(SelectItem &p)                               { }
class SelectItemArray : public ArrayOf<SelectItem, SelectItem &> { };

#define SELECT_TIMEOUT_SECS 1           // but it does (TBD)


#ifdef _WIN32

// fd_set utility functions
inline T_FD_SET *cpyfds(T_FD_SET &dst,const T_FD_SET &src)
{
    unsigned i = src.fd_count;
    dst.fd_count = i;
    while (i--)
        dst.fd_array[i] = src.fd_array[i]; // possibly better as memcpy
    return &dst;
}

inline bool findfds(T_FD_SET &s,T_SOCKET h,bool &c) 
{
    unsigned n = s.fd_count;
    unsigned i;
    for(i=0;i<n;i++) {
        if (s.fd_array[i] == h) {
            if (--n)
                s.fd_array[i] = s.fd_array[n]; // remove item
            else
                c = false;
            s.fd_count = n;
            return true;
        }
    }
    return false;
}

inline T_SOCKET popfds(T_FD_SET &s)
{
    unsigned n = s.fd_count;
    T_SOCKET ret;
    if (n) {
        ret = s.fd_array[--n];
        s.fd_count = n;
    }
    else 
        ret = NULL;
    return ret;
}

#else
#define _USE_PIPE_FOR_SELECT_TRIGGER


// not as optimized as windows but I am expecting to convert to using poll anyway
inline T_FD_SET *cpyfds(T_FD_SET &dst,const T_FD_SET &src)
{
    memcpy(&dst,&src,sizeof(T_FD_SET));
    return &dst;
}

inline bool findfds(T_FD_SET &s,T_SOCKET h,bool &c) 
{
    if ((unsigned)h>=XFD_SETSIZE)
        return false;
    return FD_ISSET(h,&s); // does not remove entry or set termination flag when done
}
#endif

class CSocketSelectThread: public Thread
{
    bool terminating;
    CriticalSection sect;
    Semaphore ticksem;
    atomic_t tickwait;
    SelectItemArray items;
    unsigned offset;
    bool selectvarschange;
    unsigned waitingchange;
    Semaphore waitingchangesem;
    int validateselecterror;
    unsigned validateerrcount;
    const char *selecttrace;
    unsigned basesize;
#ifdef _USE_PIPE_FOR_SELECT_TRIGGER
    T_SOCKET dummysock[2];
#else
    T_SOCKET dummysock; 
#endif
    bool dummysockopen;


    void opendummy()
    {
        CriticalBlock block(sect);
        if (!dummysockopen) { 
#ifdef _USE_PIPE_FOR_SELECT_TRIGGER
            if(pipe(dummysock)) {
                WARNLOG("CSocketSelectThread: create pipe failed %d",ERRNO());
                return;
            }
            for (unsigned i=0;i<2;i++) {
                int flags = fcntl(dummysock[i], F_GETFL, 0);
                if (flags!=-1) {
                    flags |= O_NONBLOCK;
                    fcntl(dummysock[i], F_SETFL, flags);
                }
                flags = fcntl(dummysock[i], F_GETFD, 0);
                if (flags!=-1) {
                    flags |=  FD_CLOEXEC;
                    fcntl(dummysock[i], F_SETFD, flags);
                }
            }
            CHECKSOCKRANGE(dummysock[0]);
#else
            if (IP6preferred)
                dummysock = ::socket(AF_INET6, SOCK_STREAM, PF_INET6);
            else
                dummysock = ::socket(AF_INET, SOCK_STREAM, 0);
            CHECKSOCKRANGE(dummysock);
#endif
            dummysockopen = true;
        }


    }

    void closedummy()
    {
        CriticalBlock block(sect);
        if (dummysockopen) { 
#ifdef _USE_PIPE_FOR_SELECT_TRIGGER
#ifdef SOCKTRACE
            PROGLOG("SOCKTRACE: Closing dummy sockets %x %d %x %d (%x)", dummysock[0], dummysock[0], dummysock[1], dummysock[1], this);
#endif
            ::close(dummysock[0]);
            ::close(dummysock[1]);
#else
#ifdef _WIN32
            ::closesocket(dummysock);
#else
            ::close(dummysock);
#endif
#endif
            dummysockopen = false;
        }
    }

    void triggerselect()
    {
        if (atomic_read(&tickwait))         
            ticksem.signal();
#ifdef _USE_PIPE_FOR_SELECT_TRIGGER
        CriticalBlock block(sect);
        char c = 0;
        if(write(dummysock[1], &c, 1) != 1) {
            int err = ERRNO();
            LOGERR(err,1,"Socket closed during trigger select");
        }
#else
        closedummy();
#endif
    }

    void resettrigger()
    {
#ifdef _USE_PIPE_FOR_SELECT_TRIGGER
        CriticalBlock block(sect);
        char c;
        while((::read(dummysock[0], &c, sizeof(c))) == sizeof(c));
#endif
    }


#ifdef _WIN32
#define HASHTABSIZE 256
#define HASHNULL (HASHTABSIZE-1)
#define HASHTABMASK (HASHTABSIZE-1)
    byte hashtab[HASHTABSIZE];
#define HASHSOCKET(s) ((((unsigned)s)>>2)&HASHTABMASK)      // with some knowledge of windows handles

    void inithash()
    {
        memset(&hashtab,HASHNULL,sizeof(hashtab));
        assertex(FD_SETSIZE<255);
    }

    void reinithash()
    { // done this way because index of items changes and hash table not that big
        inithash();
        assertex(items.ordinality()<HASHTABSIZE-1);
        ForEachItemIn(i,items) {
            unsigned h = HASHSOCKET(items.item(i).handle);
            loop {
                if (hashtab[h]==HASHNULL) {
                    hashtab[h] = (byte)i;
                    break;
                }
                if (++h==HASHTABSIZE)
                    h = 0;
            }
        }
    }

    inline SelectItem &findhash(T_SOCKET handle)
    {
        unsigned h = HASHSOCKET(handle);
        unsigned sh = h;
        loop {
            SelectItem &i=items.item(hashtab[h]);
            if (i.handle==handle) 
                return i;
            if (++h==HASHTABSIZE)
                h = 0;
            assertex(h!=sh);
        }
    }

    inline void processfds(T_FD_SET &s,byte mode,SelectItemArray &tonotify)
    {
        loop {
            T_SOCKET sock = popfds(s);
            if (!sock)
                break;
            if (sock!=dummysock) {
                SelectItem si = findhash(sock); // nb copies
                if (!si.del) {
                    si.mode = mode;
                    tonotify.append(si);
                }
            }
        }   
    }

#endif 
public:
    IMPLEMENT_IINTERFACE;
    CSocketSelectThread(const char *trc)
        : Thread("CSocketSelectThread")
    {
        dummysockopen = false;
        opendummy();
        terminating = false;
        atomic_set(&tickwait,0);
        waitingchange = 0;
        selectvarschange = false;
        validateselecterror = 0;
        validateerrcount = 0;
        offset = 0;
        selecttrace = trc;
        basesize = 0;
#ifdef _WIN32
        inithash();
#endif      
    }

    ~CSocketSelectThread()
    {
        closedummy();
        ForEachItemIn(i,items) {
            try {
                SelectItem &si = items.item(i);
                si.sock->Release();
                si.nfy->Release();
            }
            catch (IException *e) {
                EXCLOG(e,"~CSocketSelectThread");
                e->Release();
            }
        }
    }

    Owned<IException> termexcept;

    void updateItems()
    {
        // must be in CriticalBlock block(sect); 
        unsigned n = items.ordinality();
        bool hashupdateneeded = (n!=basesize); // additions all come at end
        for (unsigned i=0;i<n;) {
            SelectItem &si = items.item(i);
            if (si.del) {
                si.nfy->Release();
                try {
#ifdef SOCKTRACE
                    PROGLOG("CSocketSelectThread::updateItems release %d",si.handle);
#endif
                    si.sock->Release();
                }
                catch (IException *e) {
                    EXCLOG(e,"CSocketSelectThread::updateItems");
                    e->Release();
                }
                n--;
                if (i<n) 
                    si = items.item(n);
                items.remove(n);
                hashupdateneeded = true;
            }
            else
                i++;
        }
        assertex(n<=XFD_SETSIZE-1);
#ifdef _WIN32
        if (hashupdateneeded)
            reinithash();
#endif
        basesize = n;
    }


    bool add(ISocket *sock,unsigned mode,ISocketSelectNotify *nfy)
    {
        // maybe check once to prevent 1st delay? TBD
        CriticalBlock block(sect);
        unsigned n=0;
        ForEachItemIn(i,items) {
            SelectItem &si = items.item(i);
            if (!si.del) {
                if (si.sock==sock) {
                    si.del = true;
                }
                else 
                    n++;
            }
        }
        if (n>=XFD_SETSIZE-1)   // leave 1 spare
            return false;
        SelectItem sn;
        sn.nfy = LINK(nfy);
        sn.sock = LINK(sock);
        sn.mode = (byte)mode;
        sn.handle = (T_SOCKET)sock->OShandle();
        CHECKSOCKRANGE(sn.handle);
        sn.del = false;
        items.append(sn);
        selectvarschange = true;        
        triggerselect();
        return true;
    }

    bool remove(ISocket *sock)
    {
        if (terminating)
            return false;
        CriticalBlock block(sect);
        if (sock==NULL) { // wait until no changes outstanding
            while (selectvarschange) {
                waitingchange++;
                CriticalUnblock unblock(sect);
                waitingchangesem.wait();
            }
            return true;
        }
        ForEachItemIn(i,items) {
            SelectItem &si = items.item(i);
            if (!si.del&&(si.sock==sock)) {
                si.del = true;
                selectvarschange = true;        
                triggerselect();
                return true;
            }
        }
        return false;
    }

    void stop(bool wait)
    {
        terminating = true;
        triggerselect();
        if (wait)
            join();
    }


    bool sockOk(T_SOCKET sock)
    {
        PROGLOG("CSocketSelectThread: sockOk testing %d",sock);
        int err = 0;
        int t=0;
        socklen_t tl = sizeof(t);
        if (getsockopt(sock, SOL_SOCKET, SO_TYPE, (char *)&t, &tl)!=0) {
            StringBuffer sockstr; 
            const char *tracename = sockstr.append((unsigned)sock).str();
            LOGERR2(ERRNO(),1,"CSocketSelectThread select handle"); 
            return false;
        }
        T_FD_SET fds;
        struct timeval tv;
        XFD_ZERO(&fds);
        FD_SET((unsigned)sock, &fds);
        //FD_SET((unsigned)sock, &except);
        tv.tv_sec = 0;
        tv.tv_usec = 0;
        CHECKSOCKRANGE(sock);
        int rc = ::select( sock + 1, NULL, (fd_set *)&fds, NULL, &tv );
        if (rc<0) {
            StringBuffer sockstr; 
            const char *tracename = sockstr.append((unsigned)sock).str();
            LOGERR2(ERRNO(),2,"CSocketSelectThread select handle"); 
            return false;
        }
        else if (rc>0) 
            PROGLOG("CSocketSelectThread: select handle %d selected(2) %d",sock,rc);
        XFD_ZERO(&fds);
        FD_SET((unsigned)sock, &fds);
        tv.tv_sec = 0;
        tv.tv_usec = 0;
        rc = ::select( sock + 1, (fd_set *)&fds, NULL, NULL, &tv );
        if (rc<0) {
            StringBuffer sockstr; 
            const char *tracename = sockstr.append((unsigned)sock).str();
            LOGERR2(ERRNO(),3,"CSocketSelectThread select handle"); 
            return false;
        }
        else if (rc>0) 
            PROGLOG("CSocketSelectThread: select handle %d selected(2) %d",sock,rc);
        return true;
    }

    bool checkSocks()
    {
        bool ret = false;
        ForEachItemIn(i,items) {
            SelectItem &si = items.item(i);
            if (si.del)
                ret = true; // maybe that bad one
            else  if (!sockOk(si.handle)) {
                si.del = true;
                ret = true;
            }
        }
        return ret;
    }

    void updateSelectVars(T_FD_SET &rdfds,T_FD_SET &wrfds,T_FD_SET &exfds,bool &isrd,bool &iswr,bool &isex,unsigned &ni,T_SOCKET &max_sockid)
    {
        CriticalBlock block(sect);
        selectvarschange = false;
        if (waitingchange) {
            waitingchangesem.signal(waitingchange);
            waitingchange = 0;
        }
        if (validateselecterror) { // something went wrong so check sockets
            validateerrcount++;
            if (!checkSocks()) {
                // bad socket not found
                PROGLOG("CSocketSelectThread::updateSelectVars cannot find socket error");
                if (validateerrcount>10)
                    throw MakeStringException(-1,"CSocketSelectThread:Socket select error %d",validateselecterror);
            }
        }
        else
            validateerrcount = 0;
        updateItems();
        XFD_ZERO( &rdfds );
        XFD_ZERO( &wrfds );
        XFD_ZERO( &exfds );
        isrd=false;
        iswr=false;
        isex=false;
#ifdef _USE_PIPE_FOR_SELECT_TRIGGER
        max_sockid=dummysockopen?dummysock[0]:0;
#else
        opendummy();
        max_sockid=dummysockopen?dummysock:0;
#endif
        ni = items.ordinality();
#ifdef _WIN32
        if (offset>=ni)
#endif
            offset = 0;
        unsigned j=offset;
        ForEachItemIn(i,items) {
            SelectItem &si = items.item(j);
            j++;
            if (j==ni)
                j = 0;
            if (si.mode & SELECTMODE_READ) {
                FD_SET( si.handle, &rdfds );
                isrd = true;
            }
            if (si.mode & SELECTMODE_WRITE) {
                FD_SET( si.handle, &wrfds );
                iswr = true;
            }
            if (si.mode & SELECTMODE_EXCEPT) {
                FD_SET( si.handle, &exfds );
                isex = true;
            }
            max_sockid=std::max(si.handle, max_sockid);
        }
        if (dummysockopen) {
#ifdef _USE_PIPE_FOR_SELECT_TRIGGER
            FD_SET( dummysock[0], &rdfds );
            isrd = true;
#else
            FD_SET( dummysock, &exfds );
            isex = true;
#endif
        }
        validateselecterror = 0;
        max_sockid++;
#ifdef SOCKTRACE
        PROGLOG("SOCKTRACE: selecting on %d sockets",ni);
#endif
    }

    int run()
    {
        try {
            T_FD_SET rdfds;
            T_FD_SET wrfds;
            T_FD_SET exfds;
            timeval selecttimeout;
            bool isrd;
            bool iswr;
            bool isex;
            T_SOCKET maxsockid;
            unsigned ni;
            selectvarschange = true;
            unsigned numto = 0;
            unsigned lastnumto = 0;
            unsigned totnum = 0;
            unsigned total = 0;


            while (!terminating) {
                selecttimeout.tv_sec = SELECT_TIMEOUT_SECS;         // linux modifies so initialize inside loop
                selecttimeout.tv_usec = 0;
                if (selectvarschange) {
                    updateSelectVars(rdfds,wrfds,exfds,isrd,iswr,isex,ni,maxsockid);
                }
                if (ni==0) {
                    validateerrcount = 0;
                    atomic_inc(&tickwait);                  
                    if(!selectvarschange&&!terminating) 
                    ticksem.wait(SELECT_TIMEOUT_SECS*1000);
                    atomic_dec(&tickwait);
                        
                    continue;
                }
                T_FD_SET rs;
                T_FD_SET ws;
                T_FD_SET es;
                T_FD_SET *rsp = isrd?cpyfds(rs,rdfds):NULL;
                T_FD_SET *wsp = iswr?cpyfds(ws,wrfds):NULL;
                T_FD_SET *esp = isex?cpyfds(es,exfds):NULL;
                int n = ::select(maxsockid,(fd_set *)rsp,(fd_set *)wsp,(fd_set *)esp,&selecttimeout); // first parameter needed for posix
                if (terminating)
                    break;
                if (n < 0) {
                    CriticalBlock block(sect);
                    int err = ERRNO();
                    if (err != EINTRCALL) {
                        if (dummysockopen) {
                            LOGERR(err,12,"CSocketSelectThread select error"); // should cache error ?
                            validateselecterror = err;
#ifndef _USE_PIPE_FOR_SELECT_TRIGGER
                            closedummy();  // just in case was culprit
#endif
                        }
                        selectvarschange = true;
                        continue;
                    }
                    n = 0;
                }
                else if (n>0) { 
                    validateerrcount = 0;
                    numto = 0;
                    lastnumto = 0;
                    total += n;
                    totnum++;
                    SelectItemArray tonotify;
                    { 
                        CriticalBlock block(sect);
#ifdef _WIN32
                        if (isrd) 
                            processfds(rs,SELECTMODE_READ,tonotify);
                        if (iswr) 
                            processfds(ws,SELECTMODE_WRITE,tonotify);
                        if (isex) 
                            processfds(es,SELECTMODE_EXCEPT,tonotify);
#else
                        unsigned i;
                        SelectItem *si = items.getArray(offset);
                        SelectItem *sie = items.getArray(ni-1)+1;
                        bool r = isrd;
                        bool w = iswr;
                        bool e = isex;
#ifdef _USE_PIPE_FOR_SELECT_TRIGGER
                        if (r&&dummysockopen&&findfds(rs,dummysock[0],r)) {
                            resettrigger();
                            --n;
                        }           
#endif
                        for (i=0;(n>0)&&(i<ni);i++) {
                            if (r&&findfds(rs,si->handle,r)) {
                                if (!si->del) {
                                    tonotify.append(*si);
                                    tonotify.item(tonotify.length()-1).mode = SELECTMODE_READ;
                                }
                                --n;
                            }
                            if (w&&findfds(ws,si->handle,w)) {
                                if (!si->del) {
                                    tonotify.append(*si);
                                    tonotify.item(tonotify.length()-1).mode = SELECTMODE_WRITE;
                                }
                                --n;
                            }
                            if (e&&findfds(es,si->handle,e)) {
                                if (!si->del) {
                                    tonotify.append(*si);
                                    tonotify.item(tonotify.length()-1).mode = SELECTMODE_EXCEPT;
                                }
                                --n;
                            }
                            si++;
                            if (si==sie)
                                si = items.getArray();
                        }
#endif
                    }
                    ForEachItemIn(j,tonotify) {
                        SelectItem &si = tonotify.item(j);
                        try {
                            si.nfy->notifySelected(si.sock,si.mode); // ignore return
                        }
                        catch (IException *e) { // should be acted upon by notifySelected
                            EXCLOG(e,"CSocketSelectThread notifySelected");
                            throw ;
                        }
                    }
                }
                else  {
                    validateerrcount = 0;
                    if ((++numto>=lastnumto*2)) {
                        lastnumto = numto;
                        if (selecttrace&&(numto>4))
                            PROGLOG("%s: Select Idle(%d), %d,%d,%0.2f",selecttrace,numto,totnum,total,totnum?((double)total/(double)totnum):0.0);
                    }   
/*
                    if (numto&&(numto%100)) {
                        CriticalBlock block(sect);
                        if (!selectvarschange) 
                            selectvarschange = checkSocks();
                    }
*/
                }
                if (++offset>=ni)
                    offset = 0;

            }
        }
        catch (IException *e) {
            EXCLOG(e,"CSocketSelectThread");
            termexcept.setown(e);
        }
        CriticalBlock block(sect);
        try {
            updateItems();
        }
        catch (IException *e) {
            EXCLOG(e,"CSocketSelectThread(2)");
            if (!termexcept)
                termexcept.setown(e);
            else
                e->Release();
        }
        return 0;
    }
};


class CSocketSelectHandler: public CInterface, implements ISocketSelectHandler
{
    CIArrayOf<CSocketSelectThread> threads;
    CriticalSection sect;
    bool started;
    StringAttr selecttrace;
public:
    IMPLEMENT_IINTERFACE;
    CSocketSelectHandler(const char *trc)
        : selecttrace(trc)
    {
        started = false;
    }
    void start()
    {
        CriticalBlock block(sect);
        if (!started) {
            started = true;
            ForEachItemIn(i,threads) {
                threads.item(i).start();
            }
        }
            
    }
    void add(ISocket *sock,unsigned mode,ISocketSelectNotify *nfy)
    {
        CriticalBlock block(sect);
        loop {
            bool added=false;
            ForEachItemIn(i,threads) {
                if (added)
                    threads.item(i).remove(sock);
                else
                    added = threads.item(i).add(sock,mode,nfy);
            }
            if (added)
                return;
            CSocketSelectThread *thread = new CSocketSelectThread(selecttrace);
            threads.append(*thread);
            if (started)
                thread->start();
        }
    }
    void remove(ISocket *sock)
    {
        CriticalBlock block(sect);
        ForEachItemIn(i,threads) {
            if (threads.item(i).remove(sock)&&sock)
                break;
        }
    }
    void stop(bool wait)
    {
        IException *e=NULL;
        CriticalBlock block(sect);
        unsigned i = 0;
        while (i<threads.ordinality()) {
            CSocketSelectThread &t=threads.item(i);
            {
                CriticalUnblock unblock(sect);
                t.stop(wait);           // not quite as quick as could be if wait true
            }
            if (wait && !e && t.termexcept)
                e = t.termexcept.getClear();
            i++;
        }
#if 0 // don't throw error as too late
        if (e)
            throw e;
#else
        ::Release(e);
#endif
    }
};

ISocketSelectHandler *createSocketSelectHandler(const char *trc)
{
    return new CSocketSelectHandler(trc);
}


void readBuffer(ISocket * socket, MemoryBuffer & buffer)
{
    size32_t len;
    socket->read(&len, sizeof(len));
    _WINREV4(len);
    if (len) {
        void * target = buffer.reserve(len);
        socket->read(target, len);
    }
}

void readBuffer(ISocket * socket, MemoryBuffer & buffer, unsigned timeoutms)
{
    size32_t len;
    size32_t sizeGot;
    socket->readtms(&len, sizeof(len), sizeof(len), sizeGot, timeoutms);
    _WINREV4(len);
    if (len) {
        void * target = buffer.reserve(len);
        socket->readtms(target, len, len, sizeGot, timeoutms);
    }
}

void writeBuffer(ISocket * socket, MemoryBuffer & buffer)
{
    unsigned len = buffer.length();
    _WINREV4(len);
    socket->write(&len, sizeof(len));
    if (len)
        socket->write(buffer.toByteArray(), buffer.length());
}


bool catchReadBuffer(ISocket * socket, MemoryBuffer & buffer)
{
    try
    {
        readBuffer(socket, buffer);
        return true;
    }
    catch (IException * e)
    {
        switch (e->errorCode())
        {
        case JSOCKERR_graceful_close:
            break;
        default:
            EXCLOG(e,"catchReadBuffer");
            break;
        }
        e->Release();
    }
    return false;
}

bool catchReadBuffer(ISocket * socket, MemoryBuffer & buffer, unsigned timeoutms)
{
    try
    {
        readBuffer(socket, buffer, timeoutms);
        return true;
    }
    catch (IException * e)
    {
        switch (e->errorCode())
        {
        case JSOCKERR_graceful_close:
            break;
        default:
            EXCLOG(e,"catchReadBuffer");
            break;
        }
        e->Release();
    }
    return false;
}

bool catchWriteBuffer(ISocket * socket, MemoryBuffer & buffer)
{
    try
    {
        writeBuffer(socket, buffer);
        return true;
    }
    catch (IException * e)
    {
        EXCLOG(e,"catchWriteBuffer");
        e->Release();
    }
    return false;
}

// utility interface for simple conversations 
// conversation is always between two ends, 
// at any given time one end must be receiving and other sending (though these may swap during the conversation)
class CSingletonSocketConnection: public CInterface, implements IConversation
{
    Owned<ISocket> sock;
    Owned<ISocket> listensock;
    enum { Snone, Saccept, Sconnect, Srecv, Ssend, Scancelled } state;
    bool accepting;
    bool cancelling;
    SocketEndpoint ep;
    CriticalSection crit;
public:
    IMPLEMENT_IINTERFACE;

    CSingletonSocketConnection(SocketEndpoint &_ep)
    {
        ep = _ep;
        state = Snone;
        cancelling = false;
    }

    ~CSingletonSocketConnection()
    {
        try {
            if (sock)
                sock->close();
        }
        catch (IException *e) {
            if (e->errorCode()!=JSOCKERR_graceful_close)
                EXCLOG(e,"CSingletonSocketConnection close");
            e->Release();
        }
    }

    bool connect(unsigned timeoutms)
    {
        CriticalBlock block(crit);
        if (cancelling) 
            state = Scancelled;
        if (state==Scancelled)
            return false;
        assertex(!sock);
        ISocket *newsock=NULL;
        state = Sconnect;
        unsigned start;
        if (timeoutms!=(unsigned)INFINITE)
            start = msTick();
        while (state==Sconnect) {
            try {
                CriticalUnblock unblock(crit);
                newsock = ISocket::connect_wait(ep,1000*60*4);
                break;
            }
            catch (IException * e) {
                if ((e->errorCode()==JSOCKERR_timeout_expired)||(e->errorCode()==JSOCKERR_connection_failed)) {
                    e->Release();
                    if ((state==Sconnect)&&(timeoutms!=(unsigned)INFINITE)&&(msTick()-start>timeoutms)) {
                        state = Snone;
                        return false;
                    }
                }
                else {
                    state = Scancelled;
                    EXCLOG(e,"CSingletonSocketConnection::connect");
                    e->Release();
                    return false;
                }
            }
        }   
        if (state!=Sconnect) {
            ::Release(newsock);
            newsock = NULL;
        }
        if (!newsock) {
            state = Scancelled;
            return false;
        }
        sock.setown(newsock);
        return true;
    }

    bool send(MemoryBuffer &mb)
    {
        CriticalBlock block(crit);
        if (cancelling) 
            state = Scancelled;
        if (state==Scancelled)
            return false;
        assertex(sock);
        state = Srecv;
        try {
            CriticalUnblock unblock(crit);
            writeBuffer(sock,mb);
        }
        catch (IException * e) {
            state = Scancelled;
            EXCLOG(e,"CSingletonSocketConnection::send");
            e->Release();
            return false;
        }
        state = Snone;
        return true;
    }

    unsigned short setRandomPort(unsigned short base, unsigned num)
    {
        loop {
            try {
                ep.port = base+(unsigned short)(getRandom()%num);
                listensock.setown(ISocket::create(ep.port));
                return ep.port;
            }
            catch (IException *e) {
                if (e->errorCode()!=JSOCKERR_port_in_use) {
                    state = Scancelled;
                    EXCLOG(e,"CSingletonSocketConnection::setRandomPort");
                    e->Release();
                    break;
                }
                e->Release();
            }
        }
        return 0;
    }


    bool accept(unsigned timeoutms)
    {
        CriticalBlock block(crit);
        if (cancelling) 
            state = Scancelled;
        if (state==Scancelled)
            return false;
        if (!sock) {
            ISocket *newsock=NULL;
            state = Saccept;
            loop {
                try {
                    { 
                        CriticalUnblock unblock(crit);
                        if (!listensock)
                            listensock.setown(ISocket::create(ep.port));
                        if ((timeoutms!=(unsigned)INFINITE)&&(!listensock->wait_read(timeoutms))) {
                            state = Snone;
                            return false;
                        }
                    }
                    if (cancelling) 
                        state = Scancelled;
                    if (state==Scancelled)
                        return false;
                    { 
                        CriticalUnblock unblock(crit);
                        newsock=listensock->accept(true);
                        break;
                    }
                }
                catch (IException *e) {
                    if (e->errorCode()==JSOCKERR_graceful_close) 
                        PROGLOG("CSingletonSocketConnection: Closed socket on accept - retrying...");
                    else {
                        state = Scancelled;
                        EXCLOG(e,"CSingletonSocketConnection::accept");
                        e->Release();
                        break;
                    }
                    e->Release();
                }
            }
            if (state!=Saccept) {
                ::Release(newsock);
                newsock = NULL;
            }
            if (!newsock) {
                state = Scancelled;
                return false;
            }
            sock.setown(newsock);
        }
        return true;
    }

    bool recv(MemoryBuffer &mb, unsigned timeoutms)
    {
        CriticalBlock block(crit);
        if (cancelling) 
            state = Scancelled;
        if (state==Scancelled)
            return false;
        assertex(sock);
        state = Srecv;
        try {
            CriticalUnblock unblock(crit);
            readBuffer(sock,mb,timeoutms);
        }
        catch (IException *e) {
            if (e->errorCode()==JSOCKERR_timeout_expired)
                state = Snone;
            else {
                state = Scancelled;
                if (e->errorCode()!=JSOCKERR_graceful_close)
                    EXCLOG(e,"CSingletonSocketConnection::recv");
            }
            e->Release();
            return false;
        }
        state = Snone;
        return true;
    }

    virtual void cancel()
    {
        CriticalBlock block(crit);
        while (state!=Scancelled) {
            cancelling = true;
            try {
                switch (state) {
                case Saccept:
                    {
                        if (listensock)
                            listensock->cancel_accept();
                    }
                    break;
                case Sconnect:
                    // wait for timeout
                    break;
                case Srecv:
                    {
                        if (sock)
                            sock->close();
                    }
                    break;
                case Ssend:
                    // wait for finished
                    break;
                default:
                    state = Scancelled;
                    break;
                }
            }
            catch (IException *e) {
                EXCLOG(e,"CSingletonSocketConnection::cancel");
                e->Release();
            }
            {
                CriticalUnblock unblock(crit);
                Sleep(1000);
            }
        }
    }
};

    
IConversation *createSingletonSocketConnection(unsigned short port,SocketEndpoint *_ep)
{
    SocketEndpoint ep;
    if (_ep)
        ep = *_ep;
    if (port)
        ep.port = port;
    return new CSingletonSocketConnection(ep);
}


// interface for reading from multiple sockets using the BF_SYNC_TRANSFER_PUSH protocol 
class CSocketBufferReader: public CInterface, implements ISocketBufferReader
{
    class SocketElem: public CInterface, implements ISocketSelectNotify
    {
        CSocketBufferReader *parent;
        unsigned num;           // top bit used for ready
        MemoryAttr blk;
        CriticalSection sect;
        Linked<ISocket> sock;
        bool active;
        bool pending;
    public:
        IMPLEMENT_IINTERFACE;
        void init(CSocketBufferReader *_parent,ISocket *_sock,unsigned _n)
        {
            parent = _parent;
            num = _n;
            sock.set(_sock);
            active = true;
            pending = false;            
        }

        virtual bool notifySelected(ISocket *socket,unsigned selected)
        {
            assertex(sock==socket);
            {
                CriticalBlock block(sect);
                if (pending) {
                    active = false;
                    parent->remove(sock);  
                    return false;
                }
                pending = true;
                unsigned t1=usTick();
                size32_t sz = sock->receive_block_size();
                unsigned t2=usTick();
                if (sz)
                    sock->receive_block(blk.allocate(sz),sz);
                else
                    parent->remove(sock);  
                unsigned t3=usTick();
                if (t3-t1>60*1000000)
                    PROGLOG("CSocketBufferReader(%d): slow receive_block (%d,%d) sz=%d",num,t2-t1,t3-t2,sz);
            }
            parent->enqueue(this); // nb outside sect critical block
            return false;   // always return false
        }
        unsigned get(MemoryBuffer &mb)
        {
            CriticalBlock block(sect);
            assertex(pending);
            size32_t sz = blk.length();
            if (sz)
                mb.setBuffer(sz,blk.detach(),true);
            pending = false;
            if (!active) {
                active = true;
                parent->add(*this);  
            }
            return num;
        }
        size32_t size()
        {
            return blk.length();
        }
        ISocket *getSocket() { return sock; }
    } *elems;
    SimpleInterThreadQueueOf<SocketElem, false> readyq;
    Owned<ISocketSelectHandler> selecthandler;

    size32_t buffersize;
    size32_t buffermax;
    unsigned bufferwaiting;
    CriticalSection buffersect;
    Semaphore buffersem;
    bool isdone;

public:

    IMPLEMENT_IINTERFACE;
    CSocketBufferReader(const char *trc)
    {
        selecthandler.setown(createSocketSelectHandler(trc));
        elems = NULL;
    }
    ~CSocketBufferReader()
    {
        delete [] elems;
    }
    virtual void init(unsigned num,ISocket **sockets,size32_t _buffermax)
    {
        elems = new SocketElem[num];
        for (unsigned i=0;i<num;i++) {
            ISocket *sock = sockets[i];
            if (sock) { // can have gaps
                elems[i].init(this,sock,i);
                add(elems[i]);
            }
        }
        buffersize = 0;
        buffermax = _buffermax;
        bufferwaiting = 0;
        isdone = false;
        selecthandler->start();
    }
    virtual unsigned get(MemoryBuffer &mb)
    {
        SocketElem &e = *readyq.dequeue();
        CriticalBlock block(buffersect);
        assertex(buffersize>=e.size());
        buffersize-=e.size();
        if (bufferwaiting) {
            buffersem.signal(bufferwaiting);
            bufferwaiting = 0;
        }
        return e.get(mb);
    }
    virtual void done(bool wait)
    {
        buffersem.signal(0x10000);
        isdone = true;
        selecthandler->stop(wait);  
        if (wait) {
            delete [] elems;
            elems = NULL;
        }
    }

    void enqueue(SocketElem *elem)
    {
        if (elem) {
            CriticalBlock block(buffersect);
            size32_t sz = elem->size();
            while ((buffersize>0)&&(sz>0)&&(buffersize+sz>buffermax)) {
                if (isdone)
                    return;
                bufferwaiting++;
                CriticalUnblock unblock(buffersect);
                buffersem.wait();
            }
            buffersize += sz;
        }
        readyq.enqueue(elem);
    }

    void remove(ISocket *sock)
    {
        selecthandler->remove(sock);
    }

    void add(SocketElem &elem)
    {
        selecthandler->add(elem.getSocket(),SELECTMODE_READ,&elem);
    }
};

ISocketBufferReader *createSocketBufferReader(const char *trc)
{
    return new CSocketBufferReader(trc);
}


extern jlib_decl void markNodeCentral(SocketEndpoint &ep)
{
#ifdef CENTRAL_NODE_RANDOM_DELAY
    CriticalBlock block(CSocket::crit);
    CentralNodeArray.append(ep);
#endif
}


static CSocket *prepareSocket(unsigned idx,const SocketEndpoint &ep, ISocketConnectNotify &inotify)
{
    Owned<CSocket> sock = new CSocket(ep,sm_tcp,NULL);
    int err = sock->pre_connect(false);
    if ((err == EINPROGRESS)||(err == EWOULDBLOCK)) 
        return sock.getClear();
    if (err==0) {
        int err = sock->post_connect();
        if (err==0) 
            inotify.connected(idx,ep,sock);
        else {
            sock->errclose();
            inotify.failed(idx,ep,err);
        }
    }
    else
        inotify.failed(idx,ep,err);
    return NULL;
}

void multiConnect(const SocketEndpointArray &eps,ISocketConnectNotify &inotify,unsigned timeout)
{
    class SocketElem: public CInterface, implements ISocketSelectNotify
    {
        CriticalSection *sect;
        ISocketSelectHandler *handler;
        unsigned *remaining;
        Semaphore *notifysem;
        ISocketConnectNotify *inotify;
    public:
        Owned<CSocket> sock;
        SocketEndpoint ep;
        unsigned idx;
        IMPLEMENT_IINTERFACE;
        void init(CSocket *_sock,unsigned _idx,SocketEndpoint &_ep,CriticalSection *_sect,ISocketSelectHandler *_handler,ISocketConnectNotify *_inotify, unsigned *_remaining, Semaphore *_notifysem)
        {
            ep = _ep;
            idx = _idx;
            inotify = _inotify;
            sock.setown(_sock),
            sect = _sect;
            handler = _handler;
            remaining = _remaining;
            notifysem = _notifysem;
        }

        virtual bool notifySelected(ISocket *socket,unsigned selected)
        {
            CriticalBlock block(*sect);
            handler->remove(socket);  
            int err = sock->post_connect();
            CSocket *newsock = NULL;
            {
                CriticalUnblock unblock(*sect); // up to caller to cope with multithread
                if (err==0) 
                    inotify->connected(idx,ep,sock);
                else if ((err==ETIMEDOUT)||(err==ECONNREFUSED))  { 
                         // don't give up so easily (maybe listener not yet started (i.e. racing))
                    newsock = prepareSocket(idx,ep,*inotify);
                    Sleep(100); // not very nice but without this would just loop 
                }
                else 
                    inotify->failed(idx,ep,err);
            }
            if (newsock) {
                sock.setown(newsock);
                handler->add(sock,SELECTMODE_WRITE|SELECTMODE_EXCEPT,this);
            }
            else {
                sock.clear();
                (*remaining)--;
                notifysem->signal();
            }
            return false;
        }
    } *elems;
    unsigned n = eps.ordinality();
    unsigned remaining = n;
    if (!n)
        return;
    elems = new SocketElem[n];
    unsigned i;
    CriticalSection sect;
    Semaphore notifysem;
    Owned<ISocketSelectHandler> selecthandler = createSocketSelectHandler(
#ifdef _DEBUG
        "multiConnect"
#else
        NULL
#endif
    );

    StringBuffer name;
    for (i=0;i<n;i++) {
        CSocket* sock = prepareSocket(i,eps.item(i),inotify);
        if (sock) {
            elems[i].init(sock,i,eps.item(i),&sect,selecthandler,&inotify,&remaining,&notifysem);
            selecthandler->add(sock,SELECTMODE_WRITE|SELECTMODE_EXCEPT,&elems[i]);
        }           
        else 
            remaining--;
    }
    if (remaining) {
        unsigned lastremaining=remaining;
        selecthandler->start();
        loop {
            bool to=!notifysem.wait(timeout);
            {
                CriticalBlock block(sect);
                if (remaining==0)
                    break;
                if (to&&(remaining==lastremaining))
                    break; // nothing happened recently
                lastremaining = remaining;
            }
        }
        selecthandler->stop(true);  
    }
    selecthandler.clear();
    if (remaining) {
        for (unsigned j=0;j<n;j++) {  // mop up timeouts
            SocketElem &elem = elems[j];
            if (elem.sock.get())  {
                elem.sock.clear();
                inotify.failed(j,elem.ep,-1);
                remaining--;
                if (remaining==0)
                    break;
            }
        }
        delete [] elems;
    }
}

void multiConnect(const SocketEndpointArray &eps, PointerIArrayOf<ISocket> &retsockets,unsigned timeout)
{
    unsigned n = eps.ordinality();
    if (n==0)
        return;
    if (n==1) { // no need for multi
        ISocket *sock = NULL;
        try {
            sock = ISocket::connect_timeout(eps.item(0),timeout);
        }
        catch (IException *e) { // ignore error just append NULL
            sock = NULL;
            e->Release();
        }
        retsockets.append(sock);
        return;
    }   
    while (retsockets.ordinality()<n)
        retsockets.append(NULL);
    CriticalSection sect;
    class cNotify: implements ISocketConnectNotify
    {
        CriticalSection &sect;
        PointerIArrayOf<ISocket> &retsockets;
    public:
        cNotify(PointerIArrayOf<ISocket> &_retsockets,CriticalSection &_sect)
            : retsockets(_retsockets),sect(_sect)
        {
        }
        
        void connected(unsigned idx,const SocketEndpoint &ep,ISocket *sock)
        {
            CriticalBlock block(sect);
            assertex(idx<retsockets.ordinality());
            sock->Link();
            retsockets.replace(sock,idx);
        }
        void failed(unsigned idx,const SocketEndpoint &ep,int err)
        {
            StringBuffer s;
            PROGLOG("multiConnect failed to %s with %d",ep.getUrlStr(s).str(),err);
        }
    } notify(retsockets,sect);
    multiConnect(eps,notify,timeout);

}

inline void flushText(StringBuffer &text,unsigned short port,unsigned &rep,unsigned &range) 
{
    if (rep) {
        text.append('*').append(rep+1);
        rep = 0;
    }
    else if (range) {
        text.append('-').append(range);
        range = 0;
    }
    if (port)
        text.append(':').append(port);
}



StringBuffer &SocketEndpointArray::getText(StringBuffer &text)
{
    unsigned count = ordinality();
    if (!count)
        return text;
    if (count==1)
        return item(0).getUrlStr(text);
    byte lastip[4];
    const SocketEndpoint &first = item(0);
    bool lastis4 = first.getNetAddress(sizeof(lastip),&lastip)==sizeof(lastip);
    unsigned short lastport = first.port;
    first.getIpText(text);
    unsigned rep=0;
    unsigned range=0;
    for (unsigned i=1;i<count;i++) {
        byte ip[4];
        const SocketEndpoint &ep = item(i);
        bool is4 = ep.getNetAddress(sizeof(ip),&ip)==sizeof(ip);
        if (!lastis4||!is4) {
            flushText(text,lastport,rep,range);
            text.append(',');
            ep.getIpText(text);
        }
        else { // try and shorten
            unsigned j;
            for (j=0;j<4;j++)
                if (ip[j]!=lastip[j])
                    break;
            if (ep.port==lastport) {
                if (j==4) {
                    if (range)  // cant have range and rep
                        j--;  // pretend only 3 matched
                    else {
                        rep++;
                        continue;
                    }
                }
                else if ((j==3)&&(lastip[3]+1==ip[3])&&(rep==0)) {
                    range = ip[3];
                    lastip[3] = (byte)range;
                    continue;
                }
            }
            flushText(text,lastport,rep,range); 
            // output diff
            text.append(',');
            if (j==4)
                j--;
            for (unsigned k=j;k<4;k++) {
                if (k>j)
                    text.append('.');
                text.append((int)ip[k]);
            }
        }
        memcpy(&lastip,&ip,sizeof(lastip));
        lastis4 = is4;
        lastport = ep.port;
    }
    flushText(text,lastport,rep,range);
    return text;
}

inline const char *getnum(const char *s,unsigned &n)
{
    n = 0;
    while (isdigit(*s)) {
        n = n*10+(*s-'0');
        s++;
    }
    return s;
}

inline bool appendv4range(SocketEndpointArray *array,char *str,SocketEndpoint &ep, unsigned defport)
{
    char *s = str;
    unsigned dc = 0;
    unsigned port = defport;
    unsigned rng = 0;
    unsigned rep = 1;
    bool notip = false;
    while (*s) {
        if (*s=='.') {
            dc++;
            s++;
        }
        else if (*s==':') {
            *s = 0;
            s = (char *)getnum(s+1,port);
        }
        else if (*s=='-') {
            *s = 0;
            s = (char *)getnum(s+1,rng);
        }
        else if (*s=='*') {
            *s = 0;
            s = (char *)getnum(s+1,rep);
        }
        else {
            if (!isdigit(*s))
                notip = true;
            s++;
        }
    }
    ep.port = port;
    if (*str) {
        if (!notip&&((dc<3)&&((dc!=1)||(strlen(str)!=1)))) {
            if (!ep.isIp4()) {
                return false;
            }
            StringBuffer tmp;
            ep.getIpText(tmp);
            size32_t l = tmp.length();
            dc++;
            loop { 
                if (tmp.length()==0)
                    return false;
                if (tmp.charAt(tmp.length()-1)=='.')
                    if (--dc==0)
                        break;
                tmp.setLength(tmp.length()-1);
            }
            tmp.append(str);
            if (rng) {
                tmp.appendf("-%d",rng);
                rep = ep.ipsetrange(tmp.str());
            }
            else
                ep.ipset(tmp.str());
        }
        else if (rng) { // not nice as have to add back range (must be better way - maybe ipincrementto) TBD
            StringBuffer tmp;
            tmp.appendf("%s-%d",str,rng);
            rep = ep.ipsetrange(tmp.str());
        }
        else if (*str)
            ep.ipset(str);
        if (ep.isNull())
            ep.port = 0;
        for (unsigned i=0;i<rep;i++) {
            array->append(ep);
            if (rng)
                ep.ipincrement(1);
        }
    }
    else  {// just a port change
        if (ep.isNull())        // avoid null values with ports
            ep.port = 0;
        array->append(ep);
    }
    return true;
}

void SocketEndpointArray::fromText(const char *text,unsigned defport) 
{
    // this is quite complicated with (mixed) IPv4 and IPv6
    // only support 'full' IPv6 and no ranges


    char *str = strdup(text);
    char *s = str;
    SocketEndpoint ep;
    bool eol = false;
    loop {
        while (isspace(*s)||(*s==','))
            s++;
        if (!*s)
            break;
        char *e=s;
        if (*e=='[') {  // we have a IPv6
            while (*e&&(*e!=']'))
                e++;
            while ((*e!=',')&&!isspace(*e)) {
                if (!*s) {
                    eol = true;
                    break;
                }
                e++;
            }
            *e = 0;
            ep.set(s,defport);
            if (ep.isNull()) {
                // Error TBD
            }
            append(ep);
        }
        else {
            bool hascolon = false;
            bool isv6 = false;
            do {
                if (*e==':') {
                    if (hascolon)
                        isv6 = true;
                    else
                        hascolon = true;
                }
                e++;
                if (!*e) {
                    eol = true;
                    break;
                }
            } while (!isspace(*e)&&(*e!=','));
            *e = 0;
            if (isv6) {
                ep.set(s,defport);
                if (ep.isNull()) {
                    // Error TBD
                }
                append(ep);
            }
            else {
                if (!appendv4range(this,s,ep,defport)) {
                    // Error TBD
                }
            }

        }
        if (eol)
            break;
        s = e+1;
    }
    free(str);
}


bool IpSubNet::set(const char *_net,const char *_mask)
{
    if (!_net||!decodeNumericIP(_net,net)) {    // _net NULL means match everything
        memset(net,0,sizeof(net));
        memset(mask,0,sizeof(mask));
        return (_net==NULL);
    }
    if (!_mask||!decodeNumericIP(_mask,mask)) { // _mask NULL means match exact
        memset(mask,0xff,sizeof(mask));
        return (_mask==NULL);
    }
    if (isIp4(net)!=isIp4(mask))
        return false;
    for (unsigned j=0;j<4;j++)
        if (net[j]&~mask[j])
            return false;
    return true;
}

bool IpSubNet::test(const IpAddress &ip)
{
    unsigned i;
    if (ip.getNetAddress(sizeof(i),&i)==sizeof(i)) {
        if (!isIp4(net))
            return false;
        return (i&mask[3])==(net[3]&mask[3]);
    }
    unsigned na[4];
    if (ip.getNetAddress(sizeof(na),&na)==sizeof(na)) {
        for (unsigned j=0;j<4;j++)
            if ((na[j]&mask[j])!=(net[j]&mask[j]))
                return false;
        return true;
    }
    return false;
}

StringBuffer IpSubNet::getNetText(StringBuffer &text)
{
    char tmp[INET6_ADDRSTRLEN];
    return text.append(_inet_ntop(isIp4(net)?AF_INET:AF_INET6, &net, tmp, sizeof(tmp)));
}

StringBuffer IpSubNet::getMaskText(StringBuffer &text)
{
    char tmp[INET6_ADDRSTRLEN];
    return text.append(_inet_ntop(isIp4(net)?AF_INET:AF_INET6, &mask, tmp, sizeof(tmp))); // isIp4(net) is correct here
}

bool IpSubNet::isNull()
{
    for (unsigned i=0;i<4;i++)
        if (net[i]||mask[i])
            return false;
    return true;
}

IpSubNet &queryPreferredSubnet()
{
    return PreferredSubnet;
}

bool setPreferredSubnet(const char *ip,const char *mask)
{
    // also resets cached host IP
    if (PreferredSubnet.set(ip,mask))
    {
        if (!cachehostip.isNull()) 
        {
            cachehostip.ipset(NULL);
            queryHostIP();
        }
        return true;
    }
    else
        return false;
}

StringBuffer lookupHostName(const IpAddress &ip,StringBuffer &ret)
{
// not a common routine (no Jlib function!) only support IPv4 initially
    unsigned ipa;
    if (ip.getNetAddress(sizeof(ipa),&ipa)==sizeof(ipa)) {
        struct hostent *phostent = gethostbyaddr( (char *) &ipa, sizeof(ipa), PF_INET);
        if (phostent)
            ret.append(phostent->h_name);
        else
            ip.getIpText(ret);
    }
    else
        ip.getIpText(ret);
    return ret;
}

struct SocketEndpointHTElem
{
    IInterface *ii;
    SocketEndpoint ep;
    SocketEndpointHTElem(const SocketEndpoint _ep,IInterface *_ii) { ep.set(_ep); ii = _ii; }
    ~SocketEndpointHTElem() { ::Release(ii); }
};


class jlib_decl CSocketEndpointHashTable : public SuperHashTableOf<SocketEndpointHTElem, SocketEndpoint>, implements ISocketEndpointHashTable
{

        
    virtual void onAdd(void *) {}
    virtual void onRemove(void *e) { delete (SocketEndpointHTElem *)e; }
    
    unsigned getHashFromElement(const void *e) const
    {
        return ((const SocketEndpointHTElem *)e)->ep.hash(0);
    }
    unsigned getHashFromFindParam(const void *fp) const
    {
        return ((const SocketEndpoint *)fp)->hash(0);
    }
    const void * getFindParam(const void *p) const
    {
        return &((const SocketEndpointHTElem *)p)->ep;
    }

    bool matchesFindParam(const void * et, const void *fp, unsigned) const
    {
        return ((const SocketEndpointHTElem *)et)->ep.equals(*(SocketEndpoint *)fp);
    }

    IMPLEMENT_SUPERHASHTABLEOF_REF_FIND(SocketEndpointHTElem,SocketEndpoint);
    
public: 
    IMPLEMENT_IINTERFACE;

    CSocketEndpointHashTable() {}
    ~CSocketEndpointHashTable() { kill(); }
    
    void add(const SocketEndpoint &ep, IInterface *i)
    {
        SocketEndpointHTElem *e = SuperHashTableOf<SocketEndpointHTElem,SocketEndpoint>::find(&ep);
        if (e) {
            ::Release(e->ii);
            e->ii = i;
        }
        else {
            e = new SocketEndpointHTElem(ep,i);
            SuperHashTableOf<SocketEndpointHTElem,SocketEndpoint>::add(*e);
        }
        
    }

    void remove(const SocketEndpoint &ep)
    {
        SuperHashTableOf<SocketEndpointHTElem,SocketEndpoint>::remove(&ep);
    }

    IInterface *find(const SocketEndpoint &ep)
    {
        SocketEndpointHTElem *e = SuperHashTableOf<SocketEndpointHTElem,SocketEndpoint>::find(&ep);
        if (e) 
            return e->ii;
        return NULL;
    }
    
};


ISocketEndpointHashTable *createSocketEndpointHashTable()
{
    CSocketEndpointHashTable *ht = new CSocketEndpointHashTable;
    return ht;
}


class CSocketConnectWait: public CInterface, implements ISocketConnectWait
{
    Owned<CSocket> sock;
    bool done;
    CTimeMon connecttm;
    unsigned startt;
    bool oneshot;
    bool isopen;    
    int initerr;

    void successfulConnect()
    {
        STATS.connects++;
        STATS.connecttime+=usTick()-startt;
#ifdef _TRACE
        char peer[256];
        peer[0] = 'C';
        peer[1] = '!';
        strcpy(peer+2,sock->hostname?sock->hostname:"(NULL)");
        free(sock->tracename);
        sock->tracename = strdup(peer);
#endif              
    }

    void failedConnect()
    {
        STATS.failedconnects++;
        STATS.failedconnecttime+=usTick()-startt;
        const char* tracename = sock->tracename;
        THROWJSOCKEXCEPTION(JSOCKERR_connection_failed);
    }

public:
    IMPLEMENT_IINTERFACE;

    CSocketConnectWait(SocketEndpoint &ep,unsigned connecttimeoutms)
        : connecttm(connecttimeoutms)
    {
        oneshot = (connecttimeoutms==0); // i.e. as long as one connect takes
        done = false;
        startt = usTick();
        sock.setown(new CSocket(ep,sm_tcp,NULL));
        isopen = true;
        initerr = sock->pre_connect(false);
    }

    ISocket *wait(unsigned timems)
    {
        // this is a bit spagetti due to dual timeouts etc
        CTimeMon waittm(timems);
        unsigned refuseddelay = 1;
        bool waittimedout = false;
        bool connectimedout = false;
        do {
            bool connectdone = false;
            unsigned remaining;
            connectimedout = connecttm.timedout(&remaining);
            unsigned waitremaining;
            waittimedout = waittm.timedout(&waitremaining);
            if (oneshot||(waitremaining<remaining))
                remaining = waitremaining;
            int err = 0;
            if (!isopen||initerr) {
                isopen = true;
                err = initerr?initerr:sock->pre_connect(false);
                initerr = 0;
                if ((err == EINPROGRESS)||(err == EWOULDBLOCK))
                    err = 0; // continue
                else {
                    if (err==0) 
                        connectdone = true; // done immediately
                    else if(!oneshot) //  probably ECONNREFUSED but treat all errors same
                        refused_sleep((waitremaining==remaining)?waittm:connecttm,refuseddelay); // this stops becoming cpu bound
                }
            }
            if (!connectdone&&(err==0)) {
                SOCKET s = sock->sock;
                T_FD_SET fds;
                struct timeval tv;
                XFD_ZERO(&fds);
                FD_SET((unsigned)s, &fds);
                T_FD_SET except;
                XFD_ZERO(&except);
                FD_SET((unsigned)s, &except);
                tv.tv_sec = remaining / 1000;
                tv.tv_usec = (remaining % 1000)*1000;
                CHECKSOCKRANGE(s);
                int rc = ::select( s + 1, NULL, (fd_set *)&fds, (fd_set *)&except, &tv );
                if (rc==0) 
                    break; // timeout
                done = true;
                err = 0;
                if (rc>0) {
                    // select succeeded - return error from socket (0 if connected)
                    socklen_t errlen = sizeof(err);
                    rc = getsockopt(s, SOL_SOCKET, SO_ERROR, (char *)&err, &errlen); // check for error
                    if ((rc!=0)&&!err) 
                        err = ERRNO();  // some implementations of getsockopt duff
                    if (err&&!oneshot) //  probably ECONNREFUSED but treat all errors same
                        refused_sleep((waitremaining==remaining)?waittm:connecttm,refuseddelay); // this stops becoming cpu bound
                }
                else { // select failed
                    err = ERRNO();
                    LOGERR(err,2,"CSocketConnectWait ::select");
                }
            }
            if (err==0) {
                err = sock->post_connect();
                if (err==0) {
                    successfulConnect();
                    return sock.getClear();
                }
            }
            sock->errclose();
            isopen = false;
        } while (!waittimedout&&!oneshot);
        if (connectimedout) {
            STATS.failedconnects++;
            STATS.failedconnecttime+=usTick()-startt;
            const char* tracename = sock->tracename;
            THROWJSOCKEXCEPTION(JSOCKERR_connection_failed);
        }
        return NULL;

    }

};

ISocketConnectWait *nonBlockingConnect(SocketEndpoint &ep,unsigned connecttimeoutms)
{
    return new CSocketConnectWait(ep,connecttimeoutms);
}