trivial SOCKS5 handling in Erlang.

gistfile1.erl

#!/usr/bin/env escript

-define(VERSION, 16#05).
-define(CONNECT, 16#01).
-define(NO_AUTH, 16#00).
-define(RESERVED, 16#00).

-define(ATYP_IPV4, 16#01).
-define(ATYP_DOMAINNAME, 16#03).

-define(SUCCEEDED, 16#00).

main([Url]) ->
    {ok, Socket} = gen_tcp:connect("localhost", 9050, [binary, {active, false}]),

    % SOCKS5 with no authentication
    ok = gen_tcp:send(Socket, <<?VERSION, 1, ?NO_AUTH>>),
    {ok, <<?VERSION, ?NO_AUTH>>} = gen_tcp:recv(Socket, 0),

    % Send HTTP request via SOCKS proxy

    BinUrl = list_to_binary(Url),
    Size = byte_size(BinUrl),

    ok = gen_tcp:send(Socket,
        <<?VERSION, ?CONNECT, ?RESERVED, ?ATYP_DOMAINNAME, Size, BinUrl/binary, 80:16>>),
    {ok, Packet} = gen_tcp:recv(Socket, 0),
    <<?VERSION, ?SUCCEEDED, ?RESERVED, ?ATYP_IPV4, Addr:32, Port:16>> = Packet,
    erlang:display({negotiated, Addr, Port}),

    % Make the request.
    Request = <<"GET / HTTP/1.0\r\n\r\n">>,
    ok = gen_tcp:send(Socket, Request),
    {ok, Response} = gen_tcp:recv(Socket, 0),
    io:format("received via Tor: ~p", [Response]),
    ok.