HPCC-14220 Improve LDAP Paged Search memory management

The CPagedLDAPSearch::requestNextPage is somewhat complex with respect to
managing memory returned from several LDAP calls. Instead of remembering
to free the memory on exit, on error, and on exceptions, better to encapsulate
the pointers in a local class that deletes the memory when destructed

Signed-off-by: Russ Whitehead <william.whitehead@lexisnexis.com>

system/security/LdapSecurity/ldapconnection.cpp

@@ -1004,6 +1004,24 @@ private:
     LDAPMessage *   m_pPageEntry;
     LDAPMessage *   m_pPageBlock;
 
+    //local helper class, ensures ldap Page Control memory freed
+    class CPageControlMemWrapper
+    {
+        LDAPControl *   m_pageControl;
+        LDAPControl **  m_returnedCtrls;
+    public:
+        CPageControlMemWrapper()                        { m_pageControl = NULL; m_returnedCtrls = NULL; }
+        void setPageControl(LDAPControl * _pageCtrl)    { m_pageControl = _pageCtrl; }
+        void setRetControls(LDAPControl ** _retCtrls)   { m_returnedCtrls = _retCtrls; }
+        virtual ~CPageControlMemWrapper()
+        {
+            if (m_pageControl)
+                ldap_control_free(m_pageControl);
+            if (m_returnedCtrls)
+                ldap_controls_free(m_returnedCtrls);
+        }
+    };
+
     //---------------------------------------------------
     // Request next page of search results
     //---------------------------------------------------
@@ -1011,17 +1029,19 @@ private:
     {
         if (!m_morePages)
             return false;
-        LDAPControl * pageControl = NULL;
-        LDAPControl **  returnedCtrls = NULL;
+
+        CPageControlMemWrapper pageCtrlMem;
+
         try
         {
+            LDAPControl * pageControl = NULL;
             int rc = ldap_create_page_control(m_pLdapConn, MAX_ENTRIES, m_pCookie, false, &pageControl);//cookie gets set on first call to ldap_parse_page_control()
             if (rc != LDAP_SUCCESS)
             {
                 int err = GetLastError();
                 throw MakeStringException(-1, "ldap_create_page_control failed with 0x%x (%s)",err, ldap_err2string( err ));
             }
-
+            pageCtrlMem.setPageControl(pageControl);
             LDAPControl * svrCtrls[] = { pageControl, NULL };
 
             if (m_pPageBlock)
@@ -1033,7 +1053,6 @@ private:
                 int err = GetLastError();
                 if (err && rc != LDAP_PARTIAL_RESULTS)//389DirectoryServer sometimes returns rc, but GetLastError returns 0. In this scenario continuing the query succeeds
                 {
-                    ldap_control_free(pageControl);
                     if (m_pCookie)
                     {
                         ber_bvfree(m_pCookie);
@@ -1044,6 +1063,7 @@ private:
             }
 
             int l_errcode;
+            LDAPControl **  returnedCtrls = NULL;
             rc = ldap_parse_result(m_pLdapConn, m_pPageBlock, &l_errcode, NULL, NULL, NULL, &returnedCtrls, false);
 
             if (m_pCookie)
@@ -1054,34 +1074,21 @@ private:
 
             if (rc != LDAP_SUCCESS)
             {
-                ldap_control_free(pageControl);
                 int err = GetLastError();
                 throw MakeStringException(-1, "ldap_parse_result failed with 0x%x (%s)",err, ldap_err2string( err ));
             }
 
+            pageCtrlMem.setRetControls(returnedCtrls);
             int totCount;
             rc = ldap_parse_page_control(m_pLdapConn, returnedCtrls, &totCount, &m_pCookie);//sets cookie for next call to ldap_create_page_control()
             if (rc != LDAP_SUCCESS)
             {
-                ldap_control_free(pageControl);
-                if (returnedCtrls)
-                {
-                    ldap_controls_free(returnedCtrls);
-                    returnedCtrls = NULL;
-                }
                 int err = GetLastError();
                 throw MakeStringException(-1, "ldap_parse_page_control failed with 0x%x (%s)",err, ldap_err2string( err ));
             }
 
             if (!(m_pCookie && m_pCookie->bv_val != NULL && (strlen(m_pCookie->bv_val) > 0)))
                 m_morePages = false;
-
-            if (returnedCtrls)
-            {
-                ldap_controls_free(returnedCtrls);
-                returnedCtrls = NULL;
-            }
-            ldap_control_free(pageControl);
         }
 
         catch(IException* e)
@@ -1093,18 +1100,6 @@ private:
 
         catch(...)
         {
-            if (pageControl)
-            {
-                ldap_control_free(pageControl);
-                pageControl = NULL;
-            }
-
-            if (returnedCtrls)
-            {
-                ldap_controls_free(returnedCtrls);
-                returnedCtrls = NULL;
-            }
-
             throw MakeStringException(-1, "Unknown Exception calling LDAP Paged Search");
         }