CURLOPT_AUTOREFERER(3) Library Functions Manual CURLOPT_AUTOREFERER(3)

CURLOPT_AUTOREFERER - automatically update the referer header

#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_AUTOREFERER, long autorefer);

Pass a long parameter set to 1 to enable this. When enabled, libcurl automatically sets the Referer: header field in HTTP requests to the full URL when it follows a Location: redirect to a new destination.

The automatic referer is set to the full previous URL even when redirects are done cross-origin or following redirects to insecure protocols. This is considered a minor privacy leak by some.

With CURLINFO_REFERER(3), applications can extract the actually used referer header after the transfer.

0, disabled

HTTP

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode res;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/foo.bin");
    /* follow redirects */
    curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
    /* set Referer: automatically when following redirects */
    curl_easy_setopt(curl, CURLOPT_AUTOREFERER, 1L);
    res = curl_easy_perform(curl);
    curl_easy_cleanup(curl);
  }
}

Along with HTTP

Returns CURLE_OK if HTTP is supported, and CURLE_UNKNOWN_OPTION if not.

CURLINFO_EFFECTIVE_URL(3), CURLINFO_REDIRECT_URL(3), CURLINFO_REFERER(3), CURLOPT_FOLLOWLOCATION(3), CURLOPT_REFERER(3)

2024-05-22 libcurl