Fix for Segfault in initiate_socket_connection (socketio_berkeley) when DNS resolution fails (gh#636) (#637)

* Fix for Segfault in initiate_socket_connection (socketio_berkeley) when DNS resolution fails (gh#636)

* Add missing else statement

* Adding check to assert hostname is not NULL

---------

Co-authored-by: RLeclair <raulleclair@microsoft.com>

adapters/socketio_berkeley.c

@@ -519,6 +519,8 @@ static int initiate_socket_connection(SOCKET_IO_INSTANCE* socket_io_instance)
         }
     }
     else
+    {
+        if (socket_io_instance->hostname != NULL)
         {
             size_t hostname_len = strlen(socket_io_instance->hostname);
             if (hostname_len + 1 > sizeof(addrInfoUn.sun_path))
@@ -535,7 +537,15 @@ static int initiate_socket_connection(SOCKET_IO_INSTANCE* socket_io_instance)
                 result = 0;
             }
         }
+        else
+        {
+            LogError("Hostname is NULL");
+            result = MU_FAILURE;
+        }
+    }
 
+    if(result == 0)
+    {
         if (socket_io_instance->address_type == ADDRESS_TYPE_IP)
         {
             socket_io_instance->socket = socket(addr->ai_family, addr->ai_socktype, addr->ai_protocol);
@@ -550,18 +560,15 @@ static int initiate_socket_connection(SOCKET_IO_INSTANCE* socket_io_instance)
             LogError("Failure: socket create failure %d.", socket_io_instance->socket);
             result = MU_FAILURE;
         }
-#ifndef __APPLE__
+        #ifndef __APPLE__
         else if (socket_io_instance->target_mac_address != NULL &&
                     set_target_network_interface(socket_io_instance->socket, socket_io_instance->target_mac_address) != 0)
         {
             LogError("Failure: failed selecting target network interface (MACADDR=%s).", socket_io_instance->target_mac_address);
             result = MU_FAILURE;
         }
-#endif //__APPLE__
-
-    if(result == 0)
-    {
-        if ((-1 == (flags = fcntl(socket_io_instance->socket, F_GETFL, 0))) ||
+        #endif //__APPLE__
+        else if ((-1 == (flags = fcntl(socket_io_instance->socket, F_GETFL, 0))) ||
             (fcntl(socket_io_instance->socket, F_SETFL, flags | O_NONBLOCK) == -1))
         {
             LogError("Failure: fcntl failure.");
@@ -583,7 +590,7 @@ static int initiate_socket_connection(SOCKET_IO_INSTANCE* socket_io_instance)
                 LogError("Failure: connect failure %d.", errno);
                 result = MU_FAILURE;
             }
-            else
+            else  // result == 0 || errno == EINPROGRESS
             {
                 // Async connect will return -1.
                 result = 0;