post-callback.c (5293B)
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 * Issue an HTTP POST and provide the data through the read callback. 26 * </DESC> 27 */ 28 #include <stdio.h> 29 #include <string.h> 30 #include <curl/curl.h> 31 32 /* silly test data to POST */ 33 static const char data[]="Lorem ipsum dolor sit amet, consectetur adipiscing " 34 "elit. Sed vel urna neque. Ut quis leo metus. Quisque eleifend, ex at " 35 "laoreet rhoncus, odio ipsum semper metus, at tempus ante urna in mauris. " 36 "Suspendisse ornare tempor venenatis. Ut dui neque, pellentesque a varius " 37 "eget, mattis vitae ligula. Fusce ut pharetra est. Ut ullamcorper mi ac " 38 "sollicitudin semper. Praesent sit amet tellus varius, posuere nulla non, " 39 "rhoncus ipsum."; 40 41 struct WriteThis { 42 const char *readptr; 43 size_t sizeleft; 44 }; 45 46 static size_t read_callback(char *dest, size_t size, size_t nmemb, void *userp) 47 { 48 struct WriteThis *wt = (struct WriteThis *)userp; 49 size_t buffer_size = size*nmemb; 50 51 if(wt->sizeleft) { 52 /* copy as much as possible from the source to the destination */ 53 size_t copy_this_much = wt->sizeleft; 54 if(copy_this_much > buffer_size) 55 copy_this_much = buffer_size; 56 memcpy(dest, wt->readptr, copy_this_much); 57 58 wt->readptr += copy_this_much; 59 wt->sizeleft -= copy_this_much; 60 return copy_this_much; /* we copied this many bytes */ 61 } 62 63 return 0; /* no more data left to deliver */ 64 } 65 66 int main(void) 67 { 68 CURL *curl; 69 CURLcode res; 70 71 struct WriteThis wt; 72 73 wt.readptr = data; 74 wt.sizeleft = strlen(data); 75 76 /* In Windows, this inits the Winsock stuff */ 77 res = curl_global_init(CURL_GLOBAL_DEFAULT); 78 /* Check for errors */ 79 if(res != CURLE_OK) { 80 fprintf(stderr, "curl_global_init() failed: %s\n", 81 curl_easy_strerror(res)); 82 return 1; 83 } 84 85 /* get a curl handle */ 86 curl = curl_easy_init(); 87 if(curl) { 88 /* First set the URL that is about to receive our POST. */ 89 curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/index.cgi"); 90 91 /* Now specify we want to POST data */ 92 curl_easy_setopt(curl, CURLOPT_POST, 1L); 93 94 /* we want to use our own read function */ 95 curl_easy_setopt(curl, CURLOPT_READFUNCTION, read_callback); 96 97 /* pointer to pass to our read function */ 98 curl_easy_setopt(curl, CURLOPT_READDATA, &wt); 99 100 /* get verbose debug output please */ 101 curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L); 102 103 /* 104 If you use POST to an HTTP 1.1 server, you can send data without knowing 105 the size before starting the POST if you use chunked encoding. You 106 enable this by adding a header like "Transfer-Encoding: chunked" with 107 CURLOPT_HTTPHEADER. With HTTP 1.0 or without chunked transfer, you must 108 specify the size in the request. 109 */ 110 #ifdef USE_CHUNKED 111 { 112 struct curl_slist *chunk = NULL; 113 114 chunk = curl_slist_append(chunk, "Transfer-Encoding: chunked"); 115 res = curl_easy_setopt(curl, CURLOPT_HTTPHEADER, chunk); 116 /* use curl_slist_free_all() after the *perform() call to free this 117 list again */ 118 } 119 #else 120 /* Set the expected POST size. If you want to POST large amounts of data, 121 consider CURLOPT_POSTFIELDSIZE_LARGE */ 122 curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, (long)wt.sizeleft); 123 #endif 124 125 #ifdef DISABLE_EXPECT 126 /* 127 Using POST with HTTP 1.1 implies the use of a "Expect: 100-continue" 128 header. You can disable this header with CURLOPT_HTTPHEADER as usual. 129 NOTE: if you want chunked transfer too, you need to combine these two 130 since you can only set one list of headers with CURLOPT_HTTPHEADER. */ 131 132 /* A less good option would be to enforce HTTP 1.0, but that might also 133 have other implications. */ 134 { 135 struct curl_slist *chunk = NULL; 136 137 chunk = curl_slist_append(chunk, "Expect:"); 138 res = curl_easy_setopt(curl, CURLOPT_HTTPHEADER, chunk); 139 /* use curl_slist_free_all() after the *perform() call to free this 140 list again */ 141 } 142 #endif 143 144 /* Perform the request, res gets the return code */ 145 res = curl_easy_perform(curl); 146 /* Check for errors */ 147 if(res != CURLE_OK) 148 fprintf(stderr, "curl_easy_perform() failed: %s\n", 149 curl_easy_strerror(res)); 150 151 /* always cleanup */ 152 curl_easy_cleanup(curl); 153 } 154 curl_global_cleanup(); 155 return 0; 156 }