CURLOPT_HTTPPROXYTUNNEL(3)

💅 CURLOPT_HTTPPROXYTUNNEL(3) — tunnel through HTTP proxy ✨

Okay so this is from the Library Functions Manual, bestie, and it's giving "let's actually tunnel through the HTTP proxy" energy. 🫶 No cap.

🌸 NAME 🌸

CURLOPT_HTTPPROXYTUNNEL - tunnel through HTTP proxy

✨ SYNOPSIS ✨

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HTTPPROXYTUNNEL, long tunnel);

💖 DESCRIPTION 💖

Set the tunnel parameter to 1L to make libcurl tunnel all operations through the HTTP proxy (set with CURLOPT_PROXY(3)). There is a big difference between using a proxy and tunneling through it. Like, not the same vibe at all. 😭

Tunneling means an HTTP CONNECT request is sent to the proxy, asking it to connect to a remote host on a specific port number and then the traffic is just passed through the proxy. Proxies tend to white-list specific port numbers it allows CONNECT requests to and often only port 80 and 443 are allowed. 🙈 Lowkey restrictive, but okay.

To suppress proxy CONNECT response headers from user callbacks use CURLOPT_SUPPRESS_CONNECT_HEADERS(3). Slay. 💅

HTTP proxies can generally only speak HTTP (for obvious reasons), which makes libcurl convert non-HTTP requests to HTTP when using an HTTP proxy without this tunnel option set. For example, asking for an FTP URL and specifying an HTTP proxy makes libcurl send an FTP URL in an HTTP GET request to the proxy. By instead tunneling through the proxy, you avoid that conversion (that rarely works through the proxy anyway). Periodt. ✨

🎀 DEFAULT 🎀

0

🌈 PROTOCOLS 🌈

This functionality affects all supported protocols. All of them, bestie — iconic. ✨

🧚 EXAMPLE 🧚

int main(void)
{
  CURL *curl = curl_easy_init();
  if(curl) {
    curl_easy_setopt(curl, CURLOPT_URL, "ftp://example.com/file.txt");
    curl_easy_setopt(curl, CURLOPT_PROXY, "http://127.0.0.1:80");
    curl_easy_setopt(curl, CURLOPT_HTTPPROXYTUNNEL, 1L);
    curl_easy_perform(curl);
  }
}

🦋 AVAILABILITY 🦋

Added in curl 7.3. 🎀

⭐ 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). 💖

👑 SEE ALSO 👑

• CURLOPT_PROXY(3)
• CURLOPT_PROXYPORT(3)
• CURLOPT_PROXYTYPE(3)

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Bye bestie! Source/version libcurl, date 2026-10-12, page CURLOPT_HTTPPROXYTUNNEL(3). Mwah 💋✨