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 #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__)
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 need it for waiting. */
104 res = curl_easy_getinfo(curl, CURLINFO_ACTIVESOCKET, &sockfd);
105
106 if(res != CURLE_OK) {
107 printf("Error: %s\n", curl_easy_strerror(res));
108 return 1;
109 }
110
111 printf("Sending request.\n");
112
113 do {
114 /* Warning: This example program may loop indefinitely.
115 * A production-quality program must define a timeout and exit this loop
116 * as soon as the timeout has expired. */
117 size_t nsent;
118 do {
119 nsent = 0;
120 res = curl_easy_send(curl, request + nsent_total,
121 request_len - nsent_total, &nsent);
122 nsent_total += nsent;
123
124 if(res == CURLE_AGAIN && !wait_on_socket(sockfd, 0, 60000L)) {
125 printf("Error: timeout.\n");
126 return 1;
127 }
128 } while(res == CURLE_AGAIN);
129
130 if(res != CURLE_OK) {
131 printf("Error: %s\n", curl_easy_strerror(res));
132 return 1;
133 }
134
135 printf("Sent %lu bytes.\n", (unsigned long)nsent);
136
137 } while(nsent_total < request_len);
138
139 printf("Reading response.\n");
140
141 for(;;) {
142 /* Warning: This example program may loop indefinitely (see above). */
143 char buf[1024];
144 size_t nread;
145 do {
146 nread = 0;
147 res = curl_easy_recv(curl, buf, sizeof(buf), &nread);
148
149 if(res == CURLE_AGAIN && !wait_on_socket(sockfd, 1, 60000L)) {
150 printf("Error: timeout.\n");
151 return 1;
152 }
153 } while(res == CURLE_AGAIN);
154
155 if(res != CURLE_OK) {
156 printf("Error: %s\n", curl_easy_strerror(res));
157 break;
158 }
159
160 if(nread == 0) {
161 /* end of the response */
162 break;
163 }
164
165 printf("Received %lu bytes.\n", (unsigned long)nread);
166 }
167
168 /* always cleanup */
169 curl_easy_cleanup(curl);
170 }
171 return 0;
172 }
173
