Set the proxy to use for the upcoming request. The parameter should be a
char * to a zero terminated string holding the host name or dotted numerical
IP address. A numerical IPv6 address must be written within [brackets].
To specify port number in this string, append :[port] to the end of the host
name. The proxys port number may optionally be specified with the separate
option CURLOPT_PROXYPORT(3). If not specified, libcurl will default to
using port 1080 for proxies.
The proxy string may be prefixed with [scheme]:// to specify which kind of
proxy is used. Use socks4://, socks4a://, socks5:// or socks5h:// (the last
one to enable socks5 and asking the proxy to do the resolving, also known as
CURLPROXY_SOCKS5_HOSTNAME type) to request the specific SOCKS version to
be used. No protocol specified, http:// and all others will be treated as HTTP
Without a scheme prefix, CURLOPT_PROXYTYPE(3) can be used to specify
which kind of proxy the string identifies.
When you tell the library to use a HTTP proxy, libcurl will transparently
convert operations to HTTP even if you specify an FTP URL etc. This may have
an impact on what other features of the library you can use, such as
CURLOPT_QUOTE(3) and similar FTP specifics that dont work unless you
tunnel through the HTTP proxy. Such tunneling is activated with
libcurl respects the environment variables http_proxy, ftp_proxy,
all_proxy etc, if any of those are set. The CURLOPT_PROXY(3)
option does however override any possibly set environment variables.
Setting the proxy string to "" (an empty string) will explicitly disable the
use of a proxy, even if there is an environment variable set for it.
A proxy host string can also include protocol scheme (http://) and embedded
user + password.