mongoose/examples/websocket-server/main.c

// Copyright (c) 2020 Cesanta Software Limited
// All rights reserved
//
// Example Websocket server. Usage:
//  1. Start this server, type `make`
//  2. Open https://www.websocket.org/echo.html in your browser
//  3. In the "Location" text field, type ws://127.0.0.1:8000/websocket

#include "mongoose.h"

static const char *s_listen_on = "ws://localhost:8000";
static const char *s_web_root = ".";

// This RESTful server implements the following endpoints:
//   /websocket - upgrade to Websocket, and implement websocket echo server
//   /api/rest - respond with JSON string {"result": 123}
//   any other URI serves static files from s_web_root
static void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
  if (ev == MG_EV_OPEN) {
    // c->is_hexdumping = 1;
  } else if (ev == MG_EV_HTTP_MSG) {
    struct mg_http_message *hm = (struct mg_http_message *) ev_data;
    if (mg_http_match_uri(hm, "/websocket")) {
      // Upgrade to websocket. From now on, a connection is a full-duplex
      // Websocket connection, which will receive MG_EV_WS_MSG events.
      mg_ws_upgrade(c, hm, NULL);
    } else if (mg_http_match_uri(hm, "/rest")) {
      // Serve REST response
      mg_http_reply(c, 200, "", "{\"result\": %d}\n", 123);
    } else {
      // Serve static files
      struct mg_http_serve_opts opts = {.root_dir = s_web_root};
      mg_http_serve_dir(c, ev_data, &opts);
    }
  } else if (ev == MG_EV_WS_MSG) {
    // Got websocket frame. Received data is wm->data. Echo it back!
    struct mg_ws_message *wm = (struct mg_ws_message *) ev_data;
    mg_ws_send(c, wm->data.ptr, wm->data.len, WEBSOCKET_OP_TEXT);
  }
  (void) fn_data;
}

int main(void) {
  struct mg_mgr mgr;  // Event manager
  mg_mgr_init(&mgr);  // Initialise event manager
  printf("Starting WS listener on %s/websocket\n", s_listen_on);
  mg_http_listen(&mgr, s_listen_on, fn, NULL);  // Create HTTP listener
  for (;;) mg_mgr_poll(&mgr, 1000);             // Infinite event loop
  mg_mgr_free(&mgr);
  return 0;
}