CURLINFO_HEADER_SIZE - Man Page

#include <curl/curl.h>

CURLcode curl_easy_getinfo(CURL *handle, CURLINFO_HEADER_SIZE, long *sizep);

Pass a pointer to a long to receive the total size of all the headers received. Measured in number of bytes.

The total includes the size of any received headers suppressed by CURLOPT_SUPPRESS_CONNECT_HEADERS(3).

This functionality affects all supported protocols

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode res;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
    res = curl_easy_perform(curl);
    if(res == CURLE_OK) {
      long size;
      res = curl_easy_getinfo(curl, CURLINFO_HEADER_SIZE, &size);
      if(!res)
        printf("Header size: %ld bytes\n", size);
    }
    curl_easy_cleanup(curl);
  }
}

Added in curl 7.4.1

curl_easy_getinfo(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).

CURLINFO_REQUEST_SIZE(3), CURLINFO_SIZE_DOWNLOAD(3), curl_easy_getinfo(3), curl_easy_setopt(3)

curl_easy_getinfo(3), CURLINFO_REQUEST_SIZE(3).