I am encountering an issue where extra characters are being added to the command when sending it from WebSocat to my WebSocket server implemented in C using libwebsockets.

Here’s my WebSocket server code:

#include <libwebsockets.h>
#include <string.h>
#include <stdio.h>

static int callback_ws(struct lws *wsi, enum lws_callback_reasons reason,
                       void *user, void *in, size_t len) {
    switch (reason) {
        case LWS_CALLBACK_ESTABLISHED:
            printf("Connection establishedn");
            break;
        case LWS_CALLBACK_RECEIVE:
            printf("Message received: %sn", (char *)in);
            break;
        default:
            printf("Unhandled callback reason: %dn", reason);
            break;
    }
    return 0;
}

static struct lws_protocols protocols[] = {
    { "ws", callback_ws, 0, 1024 },
    { NULL, NULL, 0, 0 } // Terminator
};

int main(void) {
    struct lws_context_creation_info info;
    memset(&info, 0, sizeof info);
    info.port = 8080;
    info.protocols = protocols;
    struct lws_context *context = lws_create_context(&info);

    if (context == NULL) {
        fprintf(stderr, "lws init failedn");
        return -1;
    }

    printf("Starting server...n");
    while (1) {
        lws_service(context, 1000); // 1000 ms = 1 second
    }

    lws_context_destroy(context);
    return 0;
}

When I send a command, such as “open”, from WebSocat to the WebSocket server, I expect to receive only “open” on the server side. However, I observe additional characters appended to the command, for example, “openWiTG8mQpA4myt1aTI=”. This issue prevents me from properly processing the commands on the server side.

I suspect that these extra characters might be coming from a formatting issue or an encoding problem between WebSocat and the WebSocket server. Can anyone suggest a solution or provide insights into why this might be happening?