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) 16--- 17 18# NAME 19 20CURLOPT_HEADER - pass headers to the data stream 21 22# SYNOPSIS 23 24~~~c 25#include <curl/curl.h> 26 27CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HEADER, long onoff); 28~~~ 29 30# DESCRIPTION 31 32Pass the long value *onoff* set to 1 to ask libcurl to include the headers 33in the write callback (CURLOPT_WRITEFUNCTION(3)). This option is 34relevant for protocols that actually have headers or other meta-data (like 35HTTP and FTP). 36 37When asking to get the headers passed to the same callback as the body, it is 38not possible to accurately separate them again without detailed knowledge 39about the protocol in use. 40 41Further: the CURLOPT_WRITEFUNCTION(3) callback is limited to only ever 42get a maximum of *CURL_MAX_WRITE_SIZE* bytes passed to it (16KB), while a 43header can be longer and the CURLOPT_HEADERFUNCTION(3) supports getting 44called with headers up to *CURL_MAX_HTTP_HEADER* bytes big (100KB). 45 46It is often better to use CURLOPT_HEADERFUNCTION(3) to get the header 47data separately. 48 49While named confusingly similar, CURLOPT_HTTPHEADER(3) is used to set 50custom HTTP headers! 51 52# DEFAULT 53 540 55 56# EXAMPLE 57 58~~~c 59int main(void) 60{ 61 CURL *curl = curl_easy_init(); 62 if(curl) { 63 curl_easy_setopt(curl, CURLOPT_URL, "https://example.com"); 64 65 curl_easy_setopt(curl, CURLOPT_HEADER, 1L); 66 67 curl_easy_perform(curl); 68 } 69} 70~~~ 71 72# AVAILABILITY 73 74Provided in all libcurl versions. 75 76# RETURN VALUE 77 78Returns CURLE_OK. 79
