CURLOPT_PRE_PROXY(3)

1CURLOPT_PRE_PROXY(3)                libcurl               CURLOPT_PRE_PROXY(3)
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NAME

6       CURLOPT_PRE_PROXY - pre-proxy host to use
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SYNOPSIS

9       #include <curl/curl.h>
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11       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PRE_PROXY, char *preproxy);
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DESCRIPTION

14       Set  the preproxy to use for the upcoming request. The parameter should
15       be a char * to a null-terminated string holding the host name or dotted
16       numerical  IP  address. A numerical IPv6 address must be written within
17       [brackets].
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19       To specify port number in this string, append :[port] to the end of the
20       host name. The proxy's port number may optionally be specified with the
21       separate option CURLOPT_PROXYPORT(3). If not  specified,  libcurl  will
22       default to using port 1080 for proxies.
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24       A  pre  proxy is a SOCKS proxy that curl connects to before it connects
25       to the HTTP(S) proxy specified in the  CURLOPT_PROXY  option.  The  pre
26       proxy can only be a SOCKS proxy.
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28       The  pre  proxy  string  should be prefixed with [scheme]:// to specify
29       which kind of socks is used. Use socks4://,  socks4a://,  socks5://  or
30       socks5h://  (the  last  one to enable socks5 and asking the proxy to do
31       the resolving, also known as CURLPROXY_SOCKS5_HOSTNAME type) to request
32       the  specific SOCKS version to be used. Otherwise SOCKS4 is used as de‐
33       fault.
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35       Setting the pre proxy string to "" (an empty  string)  will  explicitly
36       disable the use of a pre proxy.
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38       The  application  does not have to keep the string around after setting
39       this option.
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DEFAULT

42       Default is NULL, meaning no pre proxy is used.
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44       When you set a host name to use, do not assume that there's any partic‐
45       ular single port number used widely for proxies. Specify it!
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PROTOCOLS

48       All  except  file://.  Note  that  some protocols do not work well over
49       proxy.
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EXAMPLE

52       CURL *curl = curl_easy_init();
53       if(curl) {
54         curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/file.txt");
55         curl_easy_setopt(curl, CURLOPT_PRE_PROXY, "socks4://socks-proxy:1080");
56         curl_easy_setopt(curl, CURLOPT_PROXY, "http://proxy:80");
57         curl_easy_perform(curl);
58       }
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AVAILABILITY

61       Added in 7.52.0
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RETURN VALUE

64       Returns CURLE_OK if proxies are supported, CURLE_UNKNOWN_OPTION if not,
65       or CURLE_OUT_OF_MEMORY if there was insufficient heap space.
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