1 /***************************************************************************
2 * _ _ ____ _
3 * Project ___| | | | _ \| |
4 * / __| | | | |_) | |
5 * | (__| |_| | _ <| |___
6 * \___|\___/|_| \_\_____|
7 *
8 * Copyright (C) 1998 - 2021, 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 ***************************************************************************/
22 /* <DESC>
23 * An example of curl_easy_send() and curl_easy_recv() usage.
24 * </DESC>
25 */
26
27 #include <stdio.h>
28 #include <string.h>
29 #include <curl/curl.h>
30
31 /* Auxiliary function that waits on the socket. */
wait_on_socket(curl_socket_t sockfd,int for_recv,long timeout_ms)32 static int wait_on_socket(curl_socket_t sockfd, int for_recv, long timeout_ms)
33 {
34 struct timeval tv;
35 fd_set infd, outfd, errfd;
36 int res;
37
38 tv.tv_sec = timeout_ms / 1000;
39 tv.tv_usec = (timeout_ms % 1000) * 1000;
40
41 FD_ZERO(&infd);
42 FD_ZERO(&outfd);
43 FD_ZERO(&errfd);
44
45 FD_SET(sockfd, &errfd); /* always check for error */
46
47 if(for_recv) {
48 FD_SET(sockfd, &infd);
49 }
50 else {
51 FD_SET(sockfd, &outfd);
52 }
53
54 /* select() returns the number of signalled sockets or -1 */
55 res = select((int)sockfd + 1, &infd, &outfd, &errfd, &tv);
56 return res;
57 }
58
main(void)59 int main(void)
60 {
61 CURL *curl;
62 /* Minimalistic http request */
63 const char *request = "GET / HTTP/1.0\r\nHost: example.com\r\n\r\n";
64 size_t request_len = strlen(request);
65
66 /* A general note of caution here: if you are using curl_easy_recv() or
67 curl_easy_send() to implement HTTP or _any_ other protocol libcurl
68 supports "natively", you are doing it wrong and you should stop.
69
70 This example uses HTTP only to show how to use this API, it does not
71 suggest that writing an application doing this is sensible.
72 */
73
74 curl = curl_easy_init();
75 if(curl) {
76 CURLcode res;
77 curl_socket_t sockfd;
78 size_t nsent_total = 0;
79
80 curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
81 /* Do not do the transfer - only connect to host */
82 curl_easy_setopt(curl, CURLOPT_CONNECT_ONLY, 1L);
83 res = curl_easy_perform(curl);
84
85 if(res != CURLE_OK) {
86 printf("Error: %s\n", curl_easy_strerror(res));
87 return 1;
88 }
89
90 /* Extract the socket from the curl handle - we will need it for
91 waiting. */
92 res = curl_easy_getinfo(curl, CURLINFO_ACTIVESOCKET, &sockfd);
93
94 if(res != CURLE_OK) {
95 printf("Error: %s\n", curl_easy_strerror(res));
96 return 1;
97 }
98
99 printf("Sending request.\n");
100
101 do {
102 /* Warning: This example program may loop indefinitely.
103 * A production-quality program must define a timeout and exit this loop
104 * as soon as the timeout has expired. */
105 size_t nsent;
106 do {
107 nsent = 0;
108 res = curl_easy_send(curl, request + nsent_total,
109 request_len - nsent_total, &nsent);
110 nsent_total += nsent;
111
112 if(res == CURLE_AGAIN && !wait_on_socket(sockfd, 0, 60000L)) {
113 printf("Error: timeout.\n");
114 return 1;
115 }
116 } while(res == CURLE_AGAIN);
117
118 if(res != CURLE_OK) {
119 printf("Error: %s\n", curl_easy_strerror(res));
120 return 1;
121 }
122
123 printf("Sent %" CURL_FORMAT_CURL_OFF_T " bytes.\n",
124 (curl_off_t)nsent);
125
126 } while(nsent_total < request_len);
127
128 printf("Reading response.\n");
129
130 for(;;) {
131 /* Warning: This example program may loop indefinitely (see above). */
132 char buf[1024];
133 size_t nread;
134 do {
135 nread = 0;
136 res = curl_easy_recv(curl, buf, sizeof(buf), &nread);
137
138 if(res == CURLE_AGAIN && !wait_on_socket(sockfd, 1, 60000L)) {
139 printf("Error: timeout.\n");
140 return 1;
141 }
142 } while(res == CURLE_AGAIN);
143
144 if(res != CURLE_OK) {
145 printf("Error: %s\n", curl_easy_strerror(res));
146 break;
147 }
148
149 if(nread == 0) {
150 /* end of the response */
151 break;
152 }
153
154 printf("Received %" CURL_FORMAT_CURL_OFF_T " bytes.\n",
155 (curl_off_t)nread);
156 }
157
158 /* always cleanup */
159 curl_easy_cleanup(curl);
160 }
161 return 0;
162 }
163