CURLINFO_REFERER(3)

💅 CURLINFO_REFERER — bestie, let's peek at your HTTP referrer ✨

okay so this is CURLINFO_REFERER, a libcurl thing, straight out of the Library Functions Manual. it's the little incantation you use to find out what referrer header got sent, no cap 🎀

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✨ NAME ✨

CURLINFO_REFERER — the option that grabs the used HTTP referrer request header. that's it, that's the whole vibe 💖

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🦋 SYNOPSIS 🦋

#include <curl/curl.h>

CURLcode curl_easy_getinfo(CURL *handle, CURLINFO_REFERER, char **hdrp);

like, look at her. three args, zero drama 🫶

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🌸 DESCRIPTION 🌸

so here's the tea: you pass in a pointer to a char pointer, and the function hands you back the referrer header used in the most recent request. that's literally it. main character info retrieval 💅

now the important part, bestie, do not skip this:

• the hdrp pointer is either NULL or it points to private memory
• you must not free it — nope, not yours, hands off 🙈
• that memory gets freed automatically when you call curl_easy_cleanup(3) on the corresponding curl handle. it's giving built-in cleanup, iykyk ✨

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🌈 PROTOCOLS 🌈

this functionality affects http only. that's the whole section. periodt. 🧚

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🌟 EXAMPLE 🌟

here's the actual code, copied exactly because we don't play with literals 👑

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    CURLcode result;
    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
    curl_easy_setopt(curl, CURLOPT_REFERER, "https://example.org/referrer");
    result = curl_easy_perform(curl);
    if(result == CURLE_OK) {
      char *hdr = NULL;
      curl_easy_getinfo(curl, CURLINFO_REFERER, &hdr);
      if(hdr)
        printf("Referrer header: %s\n", hdr);
    }
    curl_easy_cleanup(curl);
  }
}

so you init the handle, set CURLOPT_URL to "https://example.com", set CURLOPT_REFERER to "https://example.org/referrer", perform the request, and if it came back CURLE_OK you grab the header into hdr and print it with printf("Referrer header: %s\n", hdr). then curl_easy_cleanup because we're responsible besties 🎀 and yes the if(hdr) check is there, we stan a NULL check 💜

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🦋 AVAILABILITY 🦋

added in curl 7.76.0. if your curl is older than that, this vibe check fails, sorry 😭

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💀 RETURN VALUE 💀

curl_easy_getinfo(3) returns a CURLcode that's either success or error, no in-between bestie:

• CURLE_OK (0) — everything was OK, we ate 🔥
• non-zero — an error occurred, and you should go see libcurl-errors(3) for the details

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🎀 SEE ALSO 🎀

• CURLOPT_REFERER(3)
• curl_easy_getinfo(3)
• curl_easy_header(3)
• curl_easy_setopt(3)

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reminder bestie: do not free the memory you get back from CURLINFO_REFERER. curl_easy_cleanup(3) handles that. free it yourself and you'll be in undefined-behaviour territory, which is not the slay you want 💀

okay that's the whole page, ily, go grab your referrer headers responsibly 💖✨

— written by the libcurl girlies, libcurl, dated 2026-10-12, and that's the CURLINFO_REFERER(3) page, periodt 🫶🌸