[noPoll] Issue with using Secure Sockets client connecion (wss://) from Windows

[Kale, Rahul]

Hello,

I am facing an issue with using noPoll library for Secure Websockets (wss://)
client connection on Windows platform. Basically, the first connection from
the same binary works but subsequent connections do not work reliably.
When I tried to debug the issue, by enabling logs, the problem goes away.
Strangely, if I install my own log handler with an empty (do nothing)
implementation, the problem also goes away.
I have been trying to track down the problem the past week and finally have
something to report.

Firstly, I have isolated the code (see below) to the bare minimum below for you to reproduce the
issue. The code makes 100 back to back connections in a loop and exits the loop
early if it fails. This code rarely lasts for 2 or more loops. However if you
enable logs (setting nopoll_log_set_handler to true) or install a log
handler (using nopoll_log_set_handler), it will make 100 successful connections.

Since logging did not help, I ended up compiling the noPoll source myself for further
debugging. Since I am using VS 2008, I had to fix the code here and there to get it
to compile and also had to add __declspec(dllexport) to most functions in the header file.
By adding trial and error printfs I narrowed down the spot when it fails.
Whenever the connect fails, the SSL_connect() function errors out with
SSL_ERROR_SYSCALL at around line 756 in nopoll_conn.c.

Assuming that there is some timing issue (since logging adds just enough delay),
I have put a temporary fix as a workaround which fixes the issue: I added
a nopoll_sleep() just before SSL_connect() like so:

    nopoll_sleep (10000);
    while (SSL_connect (conn->ssl) <= 0) {
    ...


I am sure you will find the root cause and have a better fix.

Here is the sample code:

#include "nopoll.h"

static void noPollLogger(noPollCtx *ctx, noPollDebugLevel level, const char *log_msg, noPollPtr user_data) {
    // Do nothing here
}

int ConnectToWebsocket()
{

    noPollCtx * context = nopoll_ctx_new();

    //nopoll_log_set_handler(context, noPollLogger, NULL);
    nopoll_log_enable(context, false);

    noPollConnOpts * opts = nopoll_conn_opts_new();
    nopoll_conn_opts_ssl_peer_verify(opts, false); // disable cert verification
    noPollConn * connection = nopoll_conn_tls_new(context, opts, "10.1.2.3", "443", NULL,
        "wss://10.1.2.3:443/wstunnel/?dst=127.0.0.1:6060", "tunnel-protocol", "some-origin");

    bool connected = true;
    int count = 0;
    while (!nopoll_conn_is_ready(connection)) {
        if (!nopoll_conn_is_ok(connection)) {
            connected = false;
            break;
        }
        nopoll_sleep(10000);
        fprintf(stdout, "Info: Waiting for connection...\n", count++);
    }
    if (connected) {
       fprintf(stdout, "Info: Connected!!\n");
    }
    else {
       fprintf(stdout, "Failed websocket connection\n");
       exit(1);
    }

    nopoll_conn_close(connection);
    nopoll_ctx_unref(context);

    return 0;
}

int main(int argc, char *argv[])
{
    for (int i = 0; i < 100; i++) {
        ConnectToWebsocket();
        fprintf(stderr, "Done Loop %d\n", i);
    }
    return 0;
}

Thanks,

Rahul

Rahul Kale

IP Video Systems
Barco, Inc
1287 Anvilwood Ave
Sunnyvale, CA  94089

Tel  +1 408 400 4238

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