76 lines
1.8 KiB
Markdown
76 lines
1.8 KiB
Markdown
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---
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c: Copyright (C) Daniel Stenberg, <daniel.se>, et al.
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SPDX-License-Identifier: curl
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Title: CURLOPT_HTTPPROXYTUNNEL
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Section: 3
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Source: libcurl
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See-also:
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- CURLOPT_PROXY (3)
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- CURLOPT_PROXYPORT (3)
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- CURLOPT_PROXYTYPE (3)
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---
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# NAME
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CURLOPT_HTTPPROXYTUNNEL - tunnel through HTTP proxy
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# SYNOPSIS
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~~~c
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#include <curl/curl.h>
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CURLcode curl_easy_setopt(CURL *handle, CURLOPT_HTTPPROXYTUNNEL, long tunnel);
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~~~
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# DESCRIPTION
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Set the **tunnel** parameter to 1L to make libcurl tunnel all operations
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through the HTTP proxy (set with CURLOPT_PROXY(3)). There is a big
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difference between using a proxy and to tunnel through it.
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Tunneling means that an HTTP CONNECT request is sent to the proxy, asking it
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to connect to a remote host on a specific port number and then the traffic is
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just passed through the proxy. Proxies tend to white-list specific port numbers
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it allows CONNECT requests to and often only port 80 and 443 are allowed.
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To suppress proxy CONNECT response headers from user callbacks use
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CURLOPT_SUPPRESS_CONNECT_HEADERS(3).
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HTTP proxies can generally only speak HTTP (for obvious reasons), which makes
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libcurl convert non-HTTP requests to HTTP when using an HTTP proxy without
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this tunnel option set. For example, asking for an FTP URL and specifying an
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HTTP proxy makes libcurl send an FTP URL in an HTTP GET request to the
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proxy. By instead tunneling through the proxy, you avoid that conversion (that
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rarely works through the proxy anyway).
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# DEFAULT
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0
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# PROTOCOLS
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All network protocols
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# EXAMPLE
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~~~c
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int main(void)
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{
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CURL *curl = curl_easy_init();
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if(curl) {
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curl_easy_setopt(curl, CURLOPT_URL, "ftp://example.com/file.txt");
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curl_easy_setopt(curl, CURLOPT_PROXY, "http://127.0.0.1:80");
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curl_easy_setopt(curl, CURLOPT_HTTPPROXYTUNNEL, 1L);
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curl_easy_perform(curl);
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}
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}
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~~~
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# AVAILABILITY
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Always
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# RETURN VALUE
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Returns CURLE_OK
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