1 /***************************************************************************
2 * _ _ ____ _
3 * Project ___| | | | _ \| |
4 * / __| | | | |_) | |
5 * | (__| |_| | _ <| |___
6 * \___|\___/|_| \_\_____|
7 *
8 * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
9 *
10 * This software is licensed as described in the file COPYING, which
11 * you should have received as part of this distribution. The terms
12 * are also available at https://curl.se/docs/copyright.html.
13 *
14 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
15 * copies of the Software, and permit persons to whom the Software is
16 * furnished to do so, under the terms of the COPYING file.
17 *
18 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
19 * KIND, either express or implied.
20 *
21 * SPDX-License-Identifier: curl
22 *
23 ***************************************************************************/
24 /* <DESC>
25 * Demonstrate curl_easy_send() and curl_easy_recv() usage.
26 * </DESC>
27 */
28
29 #include <stdio.h>
30 #include <string.h>
31 #include <curl/curl.h>
32
33 /* Auxiliary function that waits on the socket. */
wait_on_socket(curl_socket_t sockfd,int for_recv,long timeout_ms)34 static int wait_on_socket(curl_socket_t sockfd, int for_recv, long timeout_ms)
35 {
36 struct timeval tv;
37 fd_set infd, outfd, errfd;
38 int res;
39
40 tv.tv_sec = timeout_ms / 1000;
41 tv.tv_usec = (int)(timeout_ms % 1000) * 1000;
42
43 FD_ZERO(&infd);
44 FD_ZERO(&outfd);
45 FD_ZERO(&errfd);
46
47 /* Avoid this warning with pre-2020 Cygwin/MSYS releases:
48 * warning: conversion to 'long unsigned int' from 'curl_socket_t' {aka 'int'}
49 * may change the sign of the result [-Wsign-conversion]
50 */
51 #if defined(__GNUC__) && defined(__CYGWIN__)
52 #pragma GCC diagnostic push
53 #pragma GCC diagnostic ignored "-Wsign-conversion"
54 #endif
55 FD_SET(sockfd, &errfd); /* always check for error */
56
57 if(for_recv) {
58 FD_SET(sockfd, &infd);
59 }
60 else {
61 FD_SET(sockfd, &outfd);
62 }
63 #if defined(__GNUC__) && defined(__CYGWIN__)
64 #pragma GCC diagnostic pop
65 #endif
66
67 /* select() returns the number of signalled sockets or -1 */
68 res = select((int)sockfd + 1, &infd, &outfd, &errfd, &tv);
69 return res;
70 }
71
main(void)72 int main(void)
73 {
74 CURL *curl;
75 /* Minimalistic http request */
76 const char *request = "GET / HTTP/1.0\r\nHost: example.com\r\n\r\n";
77 size_t request_len = strlen(request);
78
79 /* A general note of caution here: if you are using curl_easy_recv() or
80 curl_easy_send() to implement HTTP or _any_ other protocol libcurl
81 supports "natively", you are doing it wrong and you should stop.
82
83 This example uses HTTP only to show how to use this API, it does not
84 suggest that writing an application doing this is sensible.
85 */
86
87 curl = curl_easy_init();
88 if(curl) {
89 CURLcode res;
90 curl_socket_t sockfd;
91 size_t nsent_total = 0;
92
93 curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
94 /* Do not do the transfer - only connect to host */
95 curl_easy_setopt(curl, CURLOPT_CONNECT_ONLY, 1L);
96 res = curl_easy_perform(curl);
97
98 if(res != CURLE_OK) {
99 printf("Error: %s\n", curl_easy_strerror(res));
100 return 1;
101 }
102
103 /* Extract the socket from the curl handle - we will need it for
104 waiting. */
105 res = curl_easy_getinfo(curl, CURLINFO_ACTIVESOCKET, &sockfd);
106
107 if(res != CURLE_OK) {
108 printf("Error: %s\n", curl_easy_strerror(res));
109 return 1;
110 }
111
112 printf("Sending request.\n");
113
114 do {
115 /* Warning: This example program may loop indefinitely.
116 * A production-quality program must define a timeout and exit this loop
117 * as soon as the timeout has expired. */
118 size_t nsent;
119 do {
120 nsent = 0;
121 res = curl_easy_send(curl, request + nsent_total,
122 request_len - nsent_total, &nsent);
123 nsent_total += nsent;
124
125 if(res == CURLE_AGAIN && !wait_on_socket(sockfd, 0, 60000L)) {
126 printf("Error: timeout.\n");
127 return 1;
128 }
129 } while(res == CURLE_AGAIN);
130
131 if(res != CURLE_OK) {
132 printf("Error: %s\n", curl_easy_strerror(res));
133 return 1;
134 }
135
136 printf("Sent %lu bytes.\n", (unsigned long)nsent);
137
138 } while(nsent_total < request_len);
139
140 printf("Reading response.\n");
141
142 for(;;) {
143 /* Warning: This example program may loop indefinitely (see above). */
144 char buf[1024];
145 size_t nread;
146 do {
147 nread = 0;
148 res = curl_easy_recv(curl, buf, sizeof(buf), &nread);
149
150 if(res == CURLE_AGAIN && !wait_on_socket(sockfd, 1, 60000L)) {
151 printf("Error: timeout.\n");
152 return 1;
153 }
154 } while(res == CURLE_AGAIN);
155
156 if(res != CURLE_OK) {
157 printf("Error: %s\n", curl_easy_strerror(res));
158 break;
159 }
160
161 if(nread == 0) {
162 /* end of the response */
163 break;
164 }
165
166 printf("Received %lu bytes.\n", (unsigned long)nread);
167 }
168
169 /* always cleanup */
170 curl_easy_cleanup(curl);
171 }
172 return 0;
173 }
174