echoserver Segfault with libwebsockets v1.7.2

[MrBan]

Just tested the echoserver with both libwebsocket v1.7.2 and libwebsocket v1.7-stable. I get a segfault on the first message reception. Here is my output:

$ ./echoserver
[cppWebSockets] Not using SSL
[cppWebSockets] Server started on port 8080
[cppWebSockets] New connection
[cppWebSockets] Received: asdasd
[cppWebSockets] Error: Error writing to socket on socketID '8'
[cppWebSockets] Error: Error writing to socket
Segmentation fault (core dumped)

[mnisjk]

Thanks I'll take a look this evening

[MrBan]

I didn't find any plausible justification, but this fixes the issue:

diff --git a/WebSocketServer.cpp b/WebSocketServer.cpp
index 9609ad2..01cf74c 100644
--- a/WebSocketServer.cpp
+++ b/WebSocketServer.cpp
@@ -48,8 +48,9 @@ static int callback_main(   struct lws *wsi,
             while( !self->connections[fd]->buffer.empty( ) )
             {
                 string message = self->connections[fd]->buffer.front( ); 
-                int charsSent = lws_write( wsi, (unsigned char*)message.c_str( ), message.length( ), LWS_WRITE_TEXT );
-                if( charsSent < message.length( ) ) 
+                int msgLen = message.length();
+                int charsSent = lws_write( wsi, (unsigned char*)message.c_str(), msgLen, LWS_WRITE_TEXT );
+                if( charsSent < msgLen )
                     self->onErrorWrapper( fd, string( "Error writing to socket" ) );
                 else
                     // Only pop the message if it was sent successfully.

I verified that with the original code it always used to fall in the error branch.

[HDBaggy]

Please close this issue. As it is fixed now by updating as suggested in above comment.

[mnisjk]

Thanks @HDBaggy for opening a PR and @MrBan for the fix.

Closing this as the PR is merged but still curious about root cause. Is it a networking partition? Curious what the errno is from the underlying socket.