1---
2c: Copyright (C) Daniel Stenberg, <daniel.se>, et al.
3SPDX-License-Identifier: curl
4Title: CURLOPT_PRE_PROXY
5Section: 3
6Source: libcurl
7See-also:
8  - CURLOPT_HTTPPROXYTUNNEL (3)
9  - CURLOPT_PROXY (3)
10---
11
12# NAME
13
14CURLOPT_PRE_PROXY - pre-proxy host to use
15
16# SYNOPSIS
17
18~~~c
19#include <curl/curl.h>
20
21CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PRE_PROXY, char *preproxy);
22~~~
23
24# DESCRIPTION
25
26Set the *preproxy* to use for the upcoming request. The parameter should be a
27char * to a null-terminated string holding the hostname or dotted numerical IP
28address. A numerical IPv6 address must be written within [brackets].
29
30To specify port number in this string, append :[port] to the end of the host
31name. The proxy's port number may optionally be specified with the separate
32option CURLOPT_PROXYPORT(3). If not specified, libcurl defaults to using
33port 1080 for proxies.
34
35A pre proxy is a SOCKS proxy that curl connects to before it connects to the
36HTTP(S) proxy specified in the CURLOPT_PROXY(3) option. The pre proxy
37can only be a SOCKS proxy.
38
39The pre proxy string should be prefixed with [scheme]:// to specify which kind
40of socks is used. Use socks4://, socks4a://, socks5:// or socks5h:// (the last
41one to enable socks5 and asking the proxy to do the resolving, also known as
42*CURLPROXY_SOCKS5_HOSTNAME* type) to request the specific SOCKS version to
43be used. Otherwise SOCKS4 is used as default.
44
45Setting the pre proxy string to "" (an empty string) explicitly disables the
46use of a pre proxy.
47
48The application does not have to keep the string around after setting this
49option.
50
51# DEFAULT
52
53Default is NULL, meaning no pre proxy is used.
54
55When you set a hostname to use, do not assume that there is any particular
56single port number used widely for proxies. Specify it!
57
58# PROTOCOLS
59
60All except file://. Note that some protocols do not work well over proxy.
61
62# EXAMPLE
63
64~~~c
65int main(void)
66{
67  CURL *curl = curl_easy_init();
68  if(curl) {
69    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/file.txt");
70    curl_easy_setopt(curl, CURLOPT_PRE_PROXY, "socks4://socks-proxy:1080");
71    curl_easy_setopt(curl, CURLOPT_PROXY, "http://proxy:80");
72    curl_easy_perform(curl);
73  }
74}
75~~~
76
77# AVAILABILITY
78
79Added in 7.52.0
80
81# RETURN VALUE
82
83Returns CURLE_OK if proxies are supported, CURLE_UNKNOWN_OPTION if not, or
84CURLE_OUT_OF_MEMORY if there was insufficient heap space.
85