Minor fix for LDAP authentication: if an error occurs, we need to

manually release the LDAP handle via ldap_unbind(). This isn't a
significant problem in practice because an error eventually results
in exiting the process, but we can cleanup correctly without too
much pain.

In passing, fix an error in snprintf() usage: the "size" parameter
to snprintf() is the size of the destination buffer, including space
for the NUL terminator. Also, depending on the value of NAMEDATALEN,
the old coding could have allowed for a buffer overflow.

Author: Neil Conway

src/backend/libpq/auth.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/libpq/auth.c,v 1.145 2006/10/06 17:13:59 petere Exp $
+ *	  $PostgreSQL: pgsql/src/backend/libpq/auth.c,v 1.146 2006/11/06 01:27:52 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -716,11 +716,11 @@ CheckLDAPAuth(Port *port)
 	char		prefix[128];
 	char		suffix[128];
 	LDAP	   *ldap;
-	int			ssl = 0;
+	bool		ssl = false;
 	int			r;
 	int			ldapversion = LDAP_VERSION3;
 	int			ldapport = LDAP_PORT;
-	char		fulluser[128];
+	char		fulluser[NAMEDATALEN + 256 + 1];
 
 	if (!port->auth_arg || port->auth_arg[0] == '\0')
 	{
@@ -750,7 +750,7 @@ CheckLDAPAuth(Port *port)
 				   "ldaps://%127[^:]:%i/%127[^;];%127[^;];%127s",
 				   server, &ldapport, basedn, prefix, suffix);
 		if (r >= 3)
-			ssl = 1;
+			ssl = true;
 	}
 	if (r < 3)
 	{
@@ -766,7 +766,7 @@ CheckLDAPAuth(Port *port)
 				   "ldaps://%127[^/]/%127[^;];%127[^;];%127s",
 				   server, basedn, prefix, suffix);
 		if (r >= 2)
-			ssl = 1;
+			ssl = true;
 	}
 	if (r < 2)
 	{
@@ -799,8 +799,9 @@ CheckLDAPAuth(Port *port)
 
 	if ((r = ldap_set_option(ldap, LDAP_OPT_PROTOCOL_VERSION, &ldapversion)) != LDAP_SUCCESS)
 	{
+		ldap_unbind(ldap);
 		ereport(LOG,
-		  (errmsg("could not set LDAP protocol version: error code %d", r)));
+				(errmsg("could not set LDAP protocol version: error code %d", r)));
 		return STATUS_ERROR;
 	}
 
@@ -827,35 +828,38 @@ CheckLDAPAuth(Port *port)
 				 * should never happen since we import other files from
 				 * wldap32, but check anyway
 				 */
+				ldap_unbind(ldap);
 				ereport(LOG,
 						(errmsg("could not load wldap32.dll")));
 				return STATUS_ERROR;
 			}
 			_ldap_start_tls_sA = (__ldap_start_tls_sA) GetProcAddress(ldaphandle, "ldap_start_tls_sA");
 			if (_ldap_start_tls_sA == NULL)
 			{
+				ldap_unbind(ldap);
 				ereport(LOG,
 						(errmsg("could not load function _ldap_start_tls_sA in wldap32.dll"),
 						 errdetail("LDAP over SSL is not supported on this platform.")));
 				return STATUS_ERROR;
 			}
 
 			/*
-			 * Leak ldaphandle on purpose, because we need the library to stay
+			 * Leak LDAP handle on purpose, because we need the library to stay
 			 * open. This is ok because it will only ever be leaked once per
 			 * process and is automatically cleaned up on process exit.
 			 */
 		}
 		if ((r = _ldap_start_tls_sA(ldap, NULL, NULL, NULL, NULL)) != LDAP_SUCCESS)
 #endif
 		{
+			ldap_unbind(ldap);
 			ereport(LOG,
-			 (errmsg("could not start LDAP TLS session: error code %d", r)));
+					(errmsg("could not start LDAP TLS session: error code %d", r)));
 			return STATUS_ERROR;
 		}
 	}
 
-	snprintf(fulluser, sizeof(fulluser) - 1, "%s%s%s",
+	snprintf(fulluser, sizeof(fulluser), "%s%s%s",
 			 prefix, port->user_name, suffix);
 	fulluser[sizeof(fulluser) - 1] = '\0';