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__)
52 #pragma GCC diagnostic push
53 #pragma GCC diagnostic ignored "-Wsign-conversion"
54 #elif defined(_MSC_VER)
55 #pragma warning(push)
56 #pragma warning(disable:4127) /* conditional expression is constant */
57 #endif
58 FD_SET(sockfd, &errfd); /* always check for error */
59
60 if(for_recv) {
61 FD_SET(sockfd, &infd);
62 }
63 else {
64 FD_SET(sockfd, &outfd);
65 }
66 #if defined(__GNUC__)
67 #pragma GCC diagnostic pop
68 #elif defined(_MSC_VER)
69 #pragma warning(pop)
70 #endif
71
72 /* select() returns the number of signalled sockets or -1 */
73 res = select((int)sockfd + 1, &infd, &outfd, &errfd, &tv);
74 return res;
75 }
76
main(void)77 int main(void)
78 {
79 CURL *curl;
80 /* Minimalistic http request */
81 const char *request = "GET / HTTP/1.0\r\nHost: example.com\r\n\r\n";
82 size_t request_len = strlen(request);
83
84 /* A general note of caution here: if you are using curl_easy_recv() or
85 curl_easy_send() to implement HTTP or _any_ other protocol libcurl
86 supports "natively", you are doing it wrong and you should stop.
87
88 This example uses HTTP only to show how to use this API, it does not
89 suggest that writing an application doing this is sensible.
90 */
91
92 curl = curl_easy_init();
93 if(curl) {
94 CURLcode res;
95 curl_socket_t sockfd;
96 size_t nsent_total = 0;
97
98 curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
99 /* Do not do the transfer - only connect to host */
100 curl_easy_setopt(curl, CURLOPT_CONNECT_ONLY, 1L);
101 res = curl_easy_perform(curl);
102
103 if(res != CURLE_OK) {
104 printf("Error: %s\n", curl_easy_strerror(res));
105 return 1;
106 }
107
108 /* Extract the socket from the curl handle - we need it for waiting. */
109 res = curl_easy_getinfo(curl, CURLINFO_ACTIVESOCKET, &sockfd);
110
111 if(res != CURLE_OK) {
112 printf("Error: %s\n", curl_easy_strerror(res));
113 return 1;
114 }
115
116 printf("Sending request.\n");
117
118 do {
119 /* Warning: This example program may loop indefinitely.
120 * A production-quality program must define a timeout and exit this loop
121 * as soon as the timeout has expired. */
122 size_t nsent;
123 do {
124 nsent = 0;
125 res = curl_easy_send(curl, request + nsent_total,
126 request_len - nsent_total, &nsent);
127 nsent_total += nsent;
128
129 if(res == CURLE_AGAIN && !wait_on_socket(sockfd, 0, 60000L)) {
130 printf("Error: timeout.\n");
131 return 1;
132 }
133 } while(res == CURLE_AGAIN);
134
135 if(res != CURLE_OK) {
136 printf("Error: %s\n", curl_easy_strerror(res));
137 return 1;
138 }
139
140 printf("Sent %lu bytes.\n", (unsigned long)nsent);
141
142 } while(nsent_total < request_len);
143
144 printf("Reading response.\n");
145
146 for(;;) {
147 /* Warning: This example program may loop indefinitely (see above). */
148 char buf[1024];
149 size_t nread;
150 do {
151 nread = 0;
152 res = curl_easy_recv(curl, buf, sizeof(buf), &nread);
153
154 if(res == CURLE_AGAIN && !wait_on_socket(sockfd, 1, 60000L)) {
155 printf("Error: timeout.\n");
156 return 1;
157 }
158 } while(res == CURLE_AGAIN);
159
160 if(res != CURLE_OK) {
161 printf("Error: %s\n", curl_easy_strerror(res));
162 break;
163 }
164
165 if(nread == 0) {
166 /* end of the response */
167 break;
168 }
169
170 printf("Received %lu bytes.\n", (unsigned long)nread);
171 }
172
173 /* always cleanup */
174 curl_easy_cleanup(curl);
175 }
176 return 0;
177 }
178
