Tribblix: manual page: CURLOPT

CURLOPT_HEADER(3) Introduction to Library Functions CURLOPT_HEADER(3)

NAME

CURLOPT_HEADER - pass headers to the data stream

SYNOPSIS

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HEADER, long onoff);

DESCRIPTION

Pass the long value onoff set to 1 to ask libcurl to include the
headers in the write callback (CURLOPT_WRITEFUNCTION(3)). This option
is relevant for protocols that actually have headers or other
meta-data (like HTTP and FTP).

When asking to get the headers passed to the same callback as the
body, it is not possible to accurately separate them again without
detailed knowledge about the protocol in use.

Further: the CURLOPT_WRITEFUNCTION(3) callback is limited to only
ever get a maximum of CURL_MAX_WRITE_SIZE bytes passed to it (16KB),
while a header can be longer and the CURLOPT_HEADERFUNCTION(3)
supports getting called with headers up to CURL_MAX_HTTP_HEADER bytes
big (100KB).

It is often better to use CURLOPT_HEADERFUNCTION(3) to get the header
data separately.

While named confusingly similar, CURLOPT_HTTPHEADER(3) is used to set
custom HTTP headers.

DEFAULT

PROTOCOLS

This functionality affects ftp, http, imap, pop3 and smtp

EXAMPLE

int main(void)
{
CURL *curl = curl_easy_init();
if(curl) {
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");

curl_easy_setopt(curl, CURLOPT_HEADER, 1L);

curl_easy_perform(curl);
}
}

AVAILABILITY

Added in curl 7.1

RETURN VALUE

curl_easy_setopt(3) returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK, non-zero means an error
occurred, see libcurl-errors(3).