websocket.c
/*************************************************************************** * _ _ ____ _ * Project ___| | | | _ \| | * / __| | | | |_) | | * | (__| |_| | _ <| |___ * \___|\___/|_| \_\_____| * * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al. * * This software is licensed as described in the file COPYING, which * you should have received as part of this distribution. The terms * are also available at https://curl.se/docs/copyright.html. * * You may opt to use, copy, modify, merge, publish, distribute and/or sell * copies of the Software, and permit persons to whom the Software is * furnished to do so, under the terms of the COPYING file. * * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY * KIND, either express or implied. * * SPDX-License-Identifier: curl * ***************************************************************************/ /* <DESC> * WebSocket using CONNECT_ONLY * </DESC> */ #include <stdio.h> #include <string.h> #ifdef _WIN32 #include <winsock2.h> #include <windows.h> #define sleep(s) Sleep((DWORD)(s)) #else #include <unistd.h> #endif #include <curl/curl.h> static int ping(CURL *curl, const char *send_payload) { size_t sent; CURLcode result = curl_ws_send(curl, send_payload, strlen(send_payload), &sent, 0, CURLWS_PING); return (int)result; } static int recv_pong(CURL *curl, const char *expected_payload) { size_t rlen; const struct curl_ws_frame *meta; char buffer[256]; CURLcode result = curl_ws_recv(curl, buffer, sizeof(buffer), &rlen, &meta); if(!result) { if(meta->flags & CURLWS_PONG) { int same = 0; fprintf(stderr, "ws: got PONG back\n"); if(rlen == strlen(expected_payload)) { if(!memcmp(expected_payload, buffer, rlen)) { fprintf(stderr, "ws: got the same payload back\n"); same = 1; } } if(!same) fprintf(stderr, "ws: did NOT get the same payload back\n"); } else { fprintf(stderr, "recv_pong: got %u bytes rflags %x\n", (int)rlen, meta->flags); } } fprintf(stderr, "ws: curl_ws_recv returned %u, received %u\n", (unsigned int)result, (unsigned int)rlen); return (int)result; } static CURLcode recv_any(CURL *curl) { size_t rlen; const struct curl_ws_frame *meta; char buffer[256]; return curl_ws_recv(curl, buffer, sizeof(buffer), &rlen, &meta); } /* close the connection */ static void websocket_close(CURL *curl) { size_t sent; (void)curl_ws_send(curl, "", 0, &sent, 0, CURLWS_CLOSE); } static void websocket(CURL *curl) { int i = 0; do { recv_any(curl); if(ping(curl, "foobar")) return; if(recv_pong(curl, "foobar")) { return; } sleep(2); } while(i++ < 10); websocket_close(curl); } int main(void) { CURL *curl; CURLcode res; curl = curl_easy_init(); if(curl) { curl_easy_setopt(curl, CURLOPT_URL, "wss://example.com"); curl_easy_setopt(curl, CURLOPT_CONNECT_ONLY, 2L); /* websocket style */ /* Perform the request, res gets the return code */ res = curl_easy_perform(curl); /* Check for errors */ if(res != CURLE_OK) fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(res)); else { /* connected and ready */ websocket(curl); } /* always cleanup */ curl_easy_cleanup(curl); } return 0; }
Notice
This source code example is simplified and ignores return
codes and error checks to a large extent. We do this to highlight the libcurl
function calls and related options and reduce unrelated code.
A real-world application will of course properly check every return value and exit correctly at the first serious error.