1 /***************************************************************************
2 * _ _ ____ _
3 * Project ___| | | | _ \| |
4 * / __| | | | |_) | |
5 * | (__| |_| | _ <| |___
6 * \___|\___/|_| \_\_____|
7 *
8 * Copyright (C) 1998 - 2019, 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.haxx.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're using curl_easy_recv() or
67 curl_easy_send() to implement HTTP or _any_ other protocol libcurl
68 supports "natively", you're 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'll need it for waiting. */
91 res = curl_easy_getinfo(curl, CURLINFO_ACTIVESOCKET, &sockfd);
92
93 if(res != CURLE_OK) {
94 printf("Error: %s\n", curl_easy_strerror(res));
95 return 1;
96 }
97
98 printf("Sending request.\n");
99
100 do {
101 /* Warning: This example program may loop indefinitely.
102 * A production-quality program must define a timeout and exit this loop
103 * as soon as the timeout has expired. */
104 size_t nsent;
105 do {
106 nsent = 0;
107 res = curl_easy_send(curl, request + nsent_total,
108 request_len - nsent_total, &nsent);
109 nsent_total += nsent;
110
111 if(res == CURLE_AGAIN && !wait_on_socket(sockfd, 0, 60000L)) {
112 printf("Error: timeout.\n");
113 return 1;
114 }
115 } while(res == CURLE_AGAIN);
116
117 if(res != CURLE_OK) {
118 printf("Error: %s\n", curl_easy_strerror(res));
119 return 1;
120 }
121
122 printf("Sent %" CURL_FORMAT_CURL_OFF_T " bytes.\n",
123 (curl_off_t)nsent);
124
125 } while(nsent_total < request_len);
126
127 printf("Reading response.\n");
128
129 for(;;) {
130 /* Warning: This example program may loop indefinitely (see above). */
131 char buf[1024];
132 size_t nread;
133 do {
134 nread = 0;
135 res = curl_easy_recv(curl, buf, sizeof(buf), &nread);
136
137 if(res == CURLE_AGAIN && !wait_on_socket(sockfd, 1, 60000L)) {
138 printf("Error: timeout.\n");
139 return 1;
140 }
141 } while(res == CURLE_AGAIN);
142
143 if(res != CURLE_OK) {
144 printf("Error: %s\n", curl_easy_strerror(res));
145 break;
146 }
147
148 if(nread == 0) {
149 /* end of the response */
150 break;
151 }
152
153 printf("Received %" CURL_FORMAT_CURL_OFF_T " bytes.\n",
154 (curl_off_t)nread);
155 }
156
157 /* always cleanup */
158 curl_easy_cleanup(curl);
159 }
160 return 0;
161 }
162