1--- 2c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al. 3SPDX-License-Identifier: curl 4Title: CURLOPT_HEADER 5Section: 3 6Source: libcurl 7Protocol: 8 - HTTP 9 - FTP 10 - IMAP 11 - POP3 12 - SMTP 13See-also: 14 - CURLOPT_HEADERFUNCTION (3) 15 - CURLOPT_HTTPHEADER (3) 16Added-in: 7.1 17--- 18 19# NAME 20 21CURLOPT_HEADER - pass headers to the data stream 22 23# SYNOPSIS 24 25~~~c 26#include <curl/curl.h> 27 28CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HEADER, long onoff); 29~~~ 30 31# DESCRIPTION 32 33Pass the long value *onoff* set to 1 to ask libcurl to include the headers 34in the write callback (CURLOPT_WRITEFUNCTION(3)). This option is 35relevant for protocols that actually have headers or other meta-data (like 36HTTP and FTP). 37 38When asking to get the headers passed to the same callback as the body, it is 39not possible to accurately separate them again without detailed knowledge 40about the protocol in use. 41 42Further: the CURLOPT_WRITEFUNCTION(3) callback is limited to only ever 43get a maximum of *CURL_MAX_WRITE_SIZE* bytes passed to it (16KB), while a 44header can be longer and the CURLOPT_HEADERFUNCTION(3) supports getting 45called with headers up to *CURL_MAX_HTTP_HEADER* bytes big (100KB). 46 47It is often better to use CURLOPT_HEADERFUNCTION(3) to get the header 48data separately. 49 50While named confusingly similar, CURLOPT_HTTPHEADER(3) is used to set 51custom HTTP headers! 52 53# DEFAULT 54 550 56 57# %PROTOCOLS% 58 59# EXAMPLE 60 61~~~c 62int main(void) 63{ 64 CURL *curl = curl_easy_init(); 65 if(curl) { 66 curl_easy_setopt(curl, CURLOPT_URL, "https://example.com"); 67 68 curl_easy_setopt(curl, CURLOPT_HEADER, 1L); 69 70 curl_easy_perform(curl); 71 } 72} 73~~~ 74 75# %AVAILABILITY% 76 77# RETURN VALUE 78 79Returns CURLE_OK. 80
