CURLOPT_AUTOREFERER(3)

✨ CURLOPT_AUTOREFERER ✨

Okay so bestie, we're diving into libcurl's CURLOPT_AUTOREFERER(3) — like, this little guy lives in the Library Functions Manual and it's genuinely about automatically updating the Referer header for you. No cap. Let's get into it 💅

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🌸 NAME 🌸

CURLOPT_AUTOREFERER — automatically update the referer header 💫

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🦋 SYNOPSIS 🦋

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_AUTOREFERER, long autorefer);

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💖 DESCRIPTION 💖

So you pass a long parameter set to 1 to enable this, okay? And when it's enabled, libcurl is literally out here automatically setting the Referer: header field in HTTP requests to the full URL when it follows a Location: redirect to a new destination. Iconic behavior tbh 🎀

⚠️ Okay so listen — the automatic referer is set to the full previous URL, even when redirects are done cross-origin, and even when following redirects to insecure protocols. Some people consider this a minor privacy leak 🙈. Not me telling you what to do, just telling you what the page says. Privacy check, bestie!

And with CURLINFO_REFERER(3), applications can extract the referer header that actually got used, after the transfer. Which is super handy for peeking at what libcurl did 👀

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⭐ DEFAULT ⭐

0, disabled — so it's off unless you turn it on, periodt 💀

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🌈 PROTOCOLS 🌈

This functionality affects http only 🫶

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🧚 EXAMPLE 🧚

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode result;
    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);

    result = curl_easy_perform(curl);

    curl_easy_cleanup(curl);
  }
}

Like, look at her go 😭✨

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🔥 AVAILABILITY 🔥

Added in curl 7.1 — she's been around a minute, ngl 👑

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💜 RETURN VALUE 💜

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

CURLE_OK (0) means everything was OK 💚 — and a non-zero value means an error occurred, so go check out libcurl-errors(3) for the deets.

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👑 SEE ALSO 👑

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

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And that's the whole vibe, bestie 🍓 This libcurl page is dated 2026-10-12 and comes to you from the libcurl source, version-wise — mwah, go forth and refer correctly 💅💖🌸