mongoose/examples/websocket-client/main.c

// Copyright (c) 2020 Cesanta Software Limited
// All rights reserved
//
// Example Websocket client. Usage:
//    1. Start websocket server: cd ../websocket-server && make
//    2. In another terminal, start this client: make

#include "mongoose.h"

static const char *s_url = "ws://localhost:8000/websocket";

// Print websocket response and signal that we're done
static void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
  if (ev == MG_EV_ERROR) {
    // On error, log error message
    LOG(LL_ERROR, ("%p %s", c->fd, (char *) ev_data));
  } else if (ev == MG_EV_WS_OPEN) {
    // When websocket handshake is successful, send message
    mg_ws_send(c, "hello", 5, WEBSOCKET_OP_TEXT);
  } else if (ev == MG_EV_WS_MSG) {
    // When we get echo response, print it
    struct mg_ws_message *wm = (struct mg_ws_message *) ev_data;
    printf("GOT ECHO REPLY: [%.*s]\n", (int) wm->data.len, wm->data.ptr);
  }

  if (ev == MG_EV_ERROR || ev == MG_EV_CLOSE || ev == MG_EV_WS_MSG) {
    *(bool *) fn_data = true;  // Signal that we're done
  }
}

int main(void) {
  struct mg_mgr mgr;        // Event manager
  bool done = false;        // Event handler flips it to true
  struct mg_connection *c;  // Client connection
  mg_mgr_init(&mgr);        // Initialise event manager
  c = mg_ws_connect(&mgr, s_url, fn, &done, NULL);     // Create client
  while (c && done == false) mg_mgr_poll(&mgr, 1000);  // Wait for echo
  mg_mgr_free(&mgr);                                   // Deallocate resources
  return 0;
}