/*************************************************************************** * _ _ ____ _ * Project ___| | | | _ \| | * / __| | | | |_) | | * | (__| |_| | _ <| |___ * \___|\___/|_| \_\_____| * * Copyright (C) 1998 - 2020, Daniel Stenberg, <daniel@haxx.se>, et al. * * This software is licensed as described in the file COPYING, which * you should have received as part of this distribution. The terms * are also available at https://curl.se/docs/copyright.html. * * You may opt to use, copy, modify, merge, publish, distribute and/or sell * copies of the Software, and permit persons to whom the Software is * furnished to do so, under the terms of the COPYING file. * * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY * KIND, either express or implied. * ***************************************************************************/ /* <DESC> * Issue an HTTP POST and provide the data through the read callback. * </DESC> */ #include <stdio.h> #include <string.h> #include <curl/curl.h> /* silly test data to POST */ static const char data[]="Lorem ipsum dolor sit amet, consectetur adipiscing " "elit. Sed vel urna neque. Ut quis leo metus. Quisque eleifend, ex at " "laoreet rhoncus, odio ipsum semper metus, at tempus ante urna in mauris. " "Suspendisse ornare tempor venenatis. Ut dui neque, pellentesque a varius " "eget, mattis vitae ligula. Fusce ut pharetra est. Ut ullamcorper mi ac " "sollicitudin semper. Praesent sit amet tellus varius, posuere nulla non, " "rhoncus ipsum."; struct WriteThis { const char *readptr; size_t sizeleft; }; static size_t read_callback(char *dest, size_t size, size_t nmemb, void *userp) { struct WriteThis *wt = (struct WriteThis *)userp; size_t buffer_size = size*nmemb; if(wt->sizeleft) { /* copy as much as possible from the source to the destination */ size_t copy_this_much = wt->sizeleft; if(copy_this_much > buffer_size) copy_this_much = buffer_size; memcpy(dest, wt->readptr, copy_this_much); wt->readptr += copy_this_much; wt->sizeleft -= copy_this_much; return copy_this_much; /* we copied this many bytes */ } return 0; /* no more data left to deliver */ } int main(void) { CURL *curl; CURLcode res; struct WriteThis wt; wt.readptr = data; wt.sizeleft = strlen(data); /* In windows, this will init the winsock stuff */ res = curl_global_init(CURL_GLOBAL_DEFAULT); /* Check for errors */ if(res != CURLE_OK) { fprintf(stderr, "curl_global_init() failed: %s\n", curl_easy_strerror(res)); return 1; } /* get a curl handle */ curl = curl_easy_init(); if(curl) { /* First set the URL that is about to receive our POST. */ curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/index.cgi"); /* Now specify we want to POST data */ curl_easy_setopt(curl, CURLOPT_POST, 1L); /* we want to use our own read function */ curl_easy_setopt(curl, CURLOPT_READFUNCTION, read_callback); /* pointer to pass to our read function */ curl_easy_setopt(curl, CURLOPT_READDATA, &wt); /* get verbose debug output please */ curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L); /* If you use POST to a HTTP 1.1 server, you can send data without knowing the size before starting the POST if you use chunked encoding. You enable this by adding a header like "Transfer-Encoding: chunked" with CURLOPT_HTTPHEADER. With HTTP 1.0 or without chunked transfer, you must specify the size in the request. */ #ifdef USE_CHUNKED { struct curl_slist *chunk = NULL; chunk = curl_slist_append(chunk, "Transfer-Encoding: chunked"); res = curl_easy_setopt(curl, CURLOPT_HTTPHEADER, chunk); /* use curl_slist_free_all() after the *perform() call to free this list again */ } #else /* Set the expected POST size. If you want to POST large amounts of data, consider CURLOPT_POSTFIELDSIZE_LARGE */ curl_easy_setopt(curl, CURLOPT_POSTFIELDSIZE, (long)wt.sizeleft); #endif #ifdef DISABLE_EXPECT /* Using POST with HTTP 1.1 implies the use of a "Expect: 100-continue" header. You can disable this header with CURLOPT_HTTPHEADER as usual. NOTE: if you want chunked transfer too, you need to combine these two since you can only set one list of headers with CURLOPT_HTTPHEADER. */ /* A less good option would be to enforce HTTP 1.0, but that might also have other implications. */ { struct curl_slist *chunk = NULL; chunk = curl_slist_append(chunk, "Expect:"); res = curl_easy_setopt(curl, CURLOPT_HTTPHEADER, chunk); /* use curl_slist_free_all() after the *perform() call to free this list again */ } #endif /* Perform the request, res will get the return code */ res = curl_easy_perform(curl); /* Check for errors */ if(res != CURLE_OK) fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(res)); /* always cleanup */ curl_easy_cleanup(curl); } curl_global_cleanup(); return 0; }