CODEWITHSUNDEEP
cwebsocket
Nathaniel Blakely
Nathaniel Blakely

Reputation: 63

Websocket connection keeps prematurely closing the connection

So, I am trying to build a C application which functions as a Websockets Server.There are many related questions on here, but none of them seem to be able to help with the problem. The program is able to initially establish a connection, complete the handshake for the websocket successfully, however, cannot seem to be able to keep the connection open. On the client side, I get the error

WebSocket.js:7605 Uncaught Error: Attempt to send message on unopened or closed WebSocket at _8b2.window.WebSocket._8d2.send (WebSocket.js:7605) at (index):34

whenever I try to use the send() function on the websocket connection on the client side. And also it gives me the error

WebSocket connection to 'ws://127.0.0.1:5959/?.kl=Y' failed: WebSocket is closed before the connection is established.

Here is the source code of the server:

 int new_socket;
int activity;
int i;
int sd;
int max_sd;
int bytes_read;
fd_set readfds;
int master_socket;
noPollConn* new_conn;
/*Create no poll context*/
noPollCtx* ctx = nopoll_ctx_new();
noPollConn* conn;
char buffer[3000];
/*Create a connection listener at 127.0.0.1 (loopback) on port 5959*/
noPollConn * listener = nopoll_listener_new(ctx, "127.0.0.1","5959");
/*Get the socket of the lister*/
master_socket = nopoll_conn_socket(listener);
if(!nopoll_conn_is_ok(listener)) {
    perror("There was an error creating the listener!\n");
    exit(EXIT_FAILURE);
}
puts("Waiting for connections ...");

while(TRUE){
    printf("Start of the while loop\n");
    FD_ZERO(&readfds);
    FD_SET(master_socket, &readfds);
    max_sd = master_socket;
    printf("The number of connections is %i\n",cons);

    for (i = 0 ; i < cons ; i++) {
        sd = nopoll_conn_socket((noPollConn*)vector_get(clients,i));
        if(sd > 0)
            FD_SET(sd,&readfds);

        if(sd > max_sd)
            max_sd = sd;
    }
    printf("The max fd is %i\n",max_sd);
    activity = select(max_sd + 1 , &readfds , NULL , NULL , NULL);

    if ((activity < 0) && (errno!=EINTR)) {
        puts("select error");
        exit(EXIT_FAILURE);
    }

    if (FD_ISSET(master_socket, &readfds)){
        new_conn =  nopoll_conn_accept(ctx,listener);
        puts("Waiting for the connection to be ready");
        nopoll_conn_is_ready(conn);
        /*Vector is actually a doubly linked list*/
        vector_push(&clients,new_conn);
        cons++;
    }
    /*TODO: Implement disconnect*/
    for (i = 0; i < cons; i++){
        printf("Checking on user %i\n",i);
        conn = (noPollConn*)vector_get(clients,i);
        sd = nopoll_conn_socket(conn);
        if (FD_ISSET(sd, &readfds)){
            printf("Receiving info from socket no. %d...\n",sd);
            bytes_read = recv(sd,buffer,4000,MSG_DONTWAIT);
            buffer[bytes_read] = '\0';
            printf("Received the msg --> %s\n",buffer);

        }
    }
    memset(buffer,0,3000);
}

Just a warning though, this code does go in an infinite loop right now as I have not implemented disconnection from the client on the server side.

For the client
<pre><code>
            var connection = new WebSocket('ws://127.0.0.1:5959');
            connection.onopen = function(){
                connection.send("TEST");
                alert("Connected");
            }
            connection.onerror = function(error){
               console.log('Error detected: ' + error);
            }
            connection.onmessage = function (event) {
                alert(event.data);
            }

            connection.close();
</code></pre>

Perhaps I am missing something very important? I have gone through many tutorials, and I can't seem to figure out what the issue is. Any help is greatly appreciated! Calling .send() in the .onopen() function results in the error:

WebSocket connection to 'ws://127.0.0.1:5959/?.kl=Y' failed: WebSocket is closed before the connection is established. UPDATE
The error is on the server side. It might be related to me handling the connection as though it were a socket in some regards in the C code.

Upvotes: 0

Views: 4861

Answers (1)

guest271314
guest271314

Reputation: 1

If no errors are logged at server, the issue could be call to .send() before open event occurs. Call .send() within open event handler. Else, the issue is at server.

const socket = new WebSocket("ws://echo.websocket.org/");

socket.onopen = function(e) {
  socket.send("WebSocket rocks");
  console.log("self.socket event.type:", e.type);
};

socket.onmessage = function(e) {
  console.log(e.data);
};

socket.onerror = function(e) {
  console.log("self.socket error", e);
};

socket.onclose = function(e) {
  console.log("self.socket event.type", e.type);
};

See How do I test my WebSocket which is developed in JavaScript

plnkr http://plnkr.co/edit/W8Wgyw0mbxdMkMMe4wg4?p=preview

Upvotes: 1

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