socket: Return early from socket functions if the socket is closed

Explicitly check whether the socket is closed (universally represented
as sock->priv == NULL) before doing anything else in the socket methods.
This should safely return from unusual situations where the socket has
been closed and part-destroyed but still ends up having send() or recv()
called on it.

socket/http.c

@@ -195,6 +195,7 @@ socket_close (NiceSocket *sock)
   nice_socket_free_send_queue (&priv->send_queue);
 
   g_slice_free(HttpPriv, sock->priv);
+  sock->priv = NULL;
 }
 
 static void
@@ -280,6 +281,10 @@ socket_recv_messages (NiceSocket *sock,
   HttpPriv *priv = sock->priv;
   gint ret = -1;
 
+  /* Socket has been closed: */
+  if (sock->priv == NULL)
+    return 0;
+
   if (priv->state == HTTP_STATE_CONNECTED) {
     guint i;
 
@@ -571,6 +576,10 @@ socket_send_messages (NiceSocket *sock, const NiceAddress *to,
 {
   HttpPriv *priv = sock->priv;
 
+  /* Socket has been closed: */
+  if (sock->priv == NULL)
+    return -1;
+
   if (priv->state == HTTP_STATE_CONNECTED) {
     /* Fast path. */
     if (!priv->base_socket)

socket/pseudossl.c

@@ -173,6 +173,7 @@ socket_close (NiceSocket *sock)
   nice_socket_free_send_queue (&priv->send_queue);
 
   g_slice_free(PseudoSSLPriv, sock->priv);
+  sock->priv = NULL;
 }
 
 static gboolean
@@ -203,6 +204,10 @@ socket_recv_messages (NiceSocket *sock,
 {
   PseudoSSLPriv *priv = sock->priv;
 
+  /* Socket has been closed: */
+  if (sock->priv == NULL)
+    return 0;
+
   if (priv->handshaken) {
     if (priv->base_socket) {
       /* Fast path: once we’ve done the handshake, pass straight through to the
@@ -251,6 +256,10 @@ socket_send_messages (NiceSocket *sock, const NiceAddress *to,
 {
   PseudoSSLPriv *priv = sock->priv;
 
+  /* Socket has been closed: */
+  if (sock->priv == NULL)
+    return -1;
+
   if (priv->handshaken) {
     /* Fast path: pass directly through to the base socket once the handshake is
      * complete. */

socket/socks5.c

@@ -155,6 +155,7 @@ socket_close (NiceSocket *sock)
   nice_socket_free_send_queue (&priv->send_queue);
 
   g_slice_free(Socks5Priv, sock->priv);
+  sock->priv = NULL;
 }
 
 
@@ -166,6 +167,10 @@ socket_recv_messages (NiceSocket *sock,
   guint i;
   gint ret = -1;
 
+  /* Socket has been closed: */
+  if (sock->priv == NULL)
+    return 0;
+
   switch (priv->state) {
     case SOCKS_STATE_CONNECTED:
       /* Common case: fast pass-through to the base socket once we’re
@@ -418,6 +423,10 @@ socket_send_messages (NiceSocket *sock, const NiceAddress *to,
 {
   Socks5Priv *priv = sock->priv;
 
+  /* Socket has been closed: */
+  if (sock->priv == NULL)
+    return -1;
+
   if (priv->state == SOCKS_STATE_CONNECTED) {
     /* Fast path: pass through to the base socket once connected. */
     if (priv->base_socket == NULL)

socket/tcp-bsd.c

@@ -229,6 +229,10 @@ socket_recv_messages (NiceSocket *sock,
   TcpPriv *priv = sock->priv;
   guint i;
 
+  /* Socket has been closed: */
+  if (sock->priv == NULL)
+    return 0;
+
   /* Don't try to access the socket if it had an error */
   if (priv->error)
     return -1;
@@ -279,6 +283,10 @@ socket_send_message (NiceSocket *sock,
   GError *gerr = NULL;
   gsize message_len;
 
+  /* Socket has been closed: */
+  if (sock->priv == NULL)
+    return -1;
+
   /* Don't try to access the socket if it had an error, otherwise we risk a
    * crash with SIGPIPE (Broken pipe) */
   if (priv->error)
@@ -336,6 +344,10 @@ socket_send_messages (NiceSocket *sock, const NiceAddress *to,
 {
   guint i;
 
+  /* Socket has been closed: */
+  if (sock->priv == NULL)
+    return -1;
+
   for (i = 0; i < n_messages; i++) {
     const NiceOutputMessage *message = &messages[i];
     gssize len;

socket/udp-bsd.c

@@ -183,6 +183,10 @@ socket_recv_messages (NiceSocket *sock,
   guint i;
   gboolean error = FALSE;
 
+  /* Socket has been closed: */
+  if (sock->priv == NULL)
+    return 0;
+
   /* Read messages into recv_messages until one fails or would block, or we
    * reach the end. */
   for (i = 0; i < n_recv_messages; i++) {
@@ -285,6 +289,10 @@ socket_send_messages (NiceSocket *sock, const NiceAddress *to,
 {
   guint i;
 
+  /* Socket has been closed: */
+  if (sock->priv == NULL)
+    return -1;
+
   for (i = 0; i < n_messages; i++) {
     const NiceOutputMessage *message = &messages[i];
     gssize len;

socket/udp-turn-over-tcp.c

@@ -122,6 +122,7 @@ socket_close (NiceSocket *sock)
     nice_socket_free (priv->base_socket);
 
   g_slice_free(TurnTcpPriv, sock->priv);
+  sock->priv = NULL;
 }
 
 static gssize
@@ -133,6 +134,10 @@ socket_recv_message (NiceSocket *sock, NiceInputMessage *recv_message)
   GInputVector local_recv_buf;
   NiceInputMessage local_recv_message;
 
+  /* Socket has been closed: */
+  if (sock->priv == NULL)
+    return 0;
+
   if (priv->expecting_len == 0) {
     guint headerlen = 0;
 
@@ -236,6 +241,10 @@ socket_recv_messages (NiceSocket *nicesock,
   guint i;
   gboolean error = FALSE;
 
+  /* Socket has been closed: */
+  if (nicesock->priv == NULL)
+    return 0;
+
   for (i = 0; i < n_recv_messages; i++) {
     gssize len;
 
@@ -276,6 +285,10 @@ socket_send_message (NiceSocket *sock, const NiceAddress *to,
   } header_buf;
   guint offset = 0;
 
+  /* Socket has been closed: */
+  if (sock->priv == NULL)
+    return -1;
+
   /* Count the number of buffers. */
   if (message->n_buffers == -1) {
     n_bufs = 0;
@@ -375,6 +388,10 @@ socket_send_messages (NiceSocket *sock, const NiceAddress *to,
 {
   guint i;
 
+  /* Socket has been closed: */
+  if (sock->priv == NULL)
+    return -1;
+
   for (i = 0; i < n_messages; i++) {
     const NiceOutputMessage *message = &messages[i];
     gssize len;

socket/udp-turn.c

@@ -318,6 +318,8 @@ socket_close (NiceSocket *sock)
   g_free (priv->username);
   g_free (priv->password);
   g_free (priv);
+
+  sock->priv = NULL;
 }
 
 static gint
@@ -330,6 +332,10 @@ socket_recv_messages (NiceSocket *sock,
   gboolean error = FALSE;
   guint n_valid_messages;
 
+  /* Socket has been closed: */
+  if (sock->priv == NULL)
+    return 0;
+
   nice_debug ("received message on TURN socket");
 
   n_messages = nice_socket_recv_messages (priv->base_socket,
@@ -687,6 +693,10 @@ socket_send_message (NiceSocket *sock, const NiceAddress *to,
   ChannelBinding *binding = NULL;
   gint ret;
 
+  /* Socket has been closed: */
+  if (sock->priv == NULL)
+    return -1;
+
   for (; i; i = i->next) {
     ChannelBinding *b = i->data;
     if (nice_address_equal (&b->peer, to)) {
@@ -858,6 +868,10 @@ socket_send_messages (NiceSocket *sock, const NiceAddress *to,
 {
   guint i;
 
+  /* Socket has been closed: */
+  if (sock->priv == NULL)
+    return -1;
+
   for (i = 0; i < n_messages; i++) {
     const NiceOutputMessage *message = &messages[i];
     gssize len;