uWebSockets/capi/examples/BroadcastEchoServer.c

#include "../libuwebsockets.h"
#include <stdio.h>
#include <malloc.h>
#include <time.h>
#include <string.h>
#include <stdarg.h>

#define SSL 1


/* This is a simple WebSocket "sync" upgrade example.
 * You may compile it with "WITH_OPENSSL=1 make" or with "make" */

typedef struct
{
    size_t length;
    char *name;
} topic_t;

/* ws->getUserData returns one of these */
struct PerSocketData
{
    /* Fill with user data */
    topic_t **topics;
    int topics_quantity;
    int nr;
};

uws_app_t *app;

int buffer_size(const char *format, ...)
{
    va_list args;
    va_start(args, format);
    int result = vsnprintf(NULL, 0, format, args);
    va_end(args);
    return result + 1; // safe byte for \0
}

void listen_handler(struct us_listen_socket_t *listen_socket, uws_app_listen_config_t config, void* user_data)
{
    if (listen_socket)
    {
        printf("Listening on port wss://localhost:%d\n", config.port);
    }
}

void upgrade_handler(uws_res_t *response, uws_req_t *request, uws_socket_context_t *context)
{

    /* You may read from req only here, and COPY whatever you need into your PerSocketData.
     * PerSocketData is valid from .open to .close event, accessed with uws_ws_get_user_data(ws).
     * HttpRequest (req) is ONLY valid in this very callback, so any data you will need later
     * has to be COPIED into PerSocketData here. */

    /* Immediately upgrading without doing anything "async" before, is simple */

    struct PerSocketData *data = (struct PerSocketData *)malloc(sizeof(struct PerSocketData));
    data->topics = (topic_t **)calloc(32, sizeof(topic_t *));
    data->topics_quantity = 32;
    data->nr = 0;

    const char *ws_key = NULL;
    const char *ws_protocol = NULL;
    const char *ws_extensions = NULL;
    
    size_t ws_key_length = uws_req_get_header(request, "sec-websocket-key", 17, &ws_key);
    size_t ws_protocol_length = uws_req_get_header(request, "sec-websocket-protocol", 22, &ws_protocol);
    size_t ws_extensions_length = uws_req_get_header(request, "sec-websocket-extensions", 24, &ws_extensions);

    uws_res_upgrade(SSL,
                    response,
                    (void *)data,
                    ws_key,
                    ws_key_length,
                    ws_protocol,
                    ws_protocol_length,
                    ws_extensions,
                    ws_extensions_length,
                    context);
}

void open_handler(uws_websocket_t *ws)
{

    /* Open event here, you may access  uws_ws_get_user_data(ws) which points to a PerSocketData struct */
    struct PerSocketData *data = (struct PerSocketData *)uws_ws_get_user_data(SSL, ws);
    for (int i = 0; i < data->topics_quantity; i++)
    {

        char *topic = (char *)malloc((size_t)buffer_size("%ld-%d", (uintptr_t)ws, i));
        size_t topic_length = sprintf(topic, "%ld-%d", (uintptr_t)ws, i);

        topic_t *new_topic = (topic_t*) malloc(sizeof(topic_t));
        new_topic->length = topic_length;
        new_topic->name = topic;
        data->topics[i] = new_topic;
        uws_ws_subscribe(SSL, ws, topic, topic_length);
    }
}

void message_handler(uws_websocket_t *ws, const char *message, size_t length, uws_opcode_t opcode)
{
    struct PerSocketData *data = (struct PerSocketData *)uws_ws_get_user_data(SSL, ws);
    topic_t *topic = data->topics[(size_t)(++data->nr % data->topics_quantity)];
    uws_publish(SSL, app, topic->name, topic->length, message, length, opcode, false);

    topic = data->topics[(size_t)(++data->nr % data->topics_quantity)];
    uws_ws_publish(SSL, ws, topic->name, topic->length, message, length);
}

void close_handler(uws_websocket_t *ws, int code, const char *message, size_t length)
{
    /* You may access uws_ws_get_user_data(ws) here, but sending or
     * doing any kind of I/O with the socket is not valid. */
    struct PerSocketData *data = (struct PerSocketData *)uws_ws_get_user_data(SSL, ws);
    if (data)
    {
        for (int i = 0; i < data->topics_quantity; i++)
        {

            topic_t* topic = data->topics[i];
            free(topic->name);
            free(topic);
        }
        free(data->topics);
        free(data);
    }
}

void drain_handler(uws_websocket_t *ws)
{
    /* Check uws_ws_get_buffered_amount(ws) here */
}

void ping_handler(uws_websocket_t *ws, const char *message, size_t length)
{
    /* You don't need to handle this one, we automatically respond to pings as per standard */
}

void pong_handler(uws_websocket_t *ws, const char *message, size_t length)
{

    /* You don't need to handle this one either */
}

int main()
{


    uws_app_t *app = uws_create_app(SSL, (struct us_socket_context_options_t){
        /* There are example certificates in uWebSockets.js repo */
	    .key_file_name = "../misc/key.pem",
	    .cert_file_name = "../misc/cert.pem",
	    .passphrase = "1234"
    });

    uws_ws(SSL, app, "/*", (uws_socket_behavior_t){
                          .compression = uws_compress_options_t::SHARED_COMPRESSOR,
                          .maxPayloadLength = 16 * 1024,
                          .idleTimeout = 12,
                          .maxBackpressure = 1 * 1024 * 1024,
                          .upgrade = upgrade_handler,
                          .open = open_handler,
                          .message = message_handler,
                          .drain = drain_handler,
                          .ping = ping_handler,
                          .pong = pong_handler,
                          .close = close_handler,
                      });

    uws_app_listen(SSL, app, 9001, listen_handler, NULL);

    uws_app_run(SSL, app);
}