SOCKS是一種網絡傳輸協定,主要用于用戶端與外網伺服器之間通訊的中間傳遞,也就是用作代理的場景。SOCKS是"SOCKet Secure"的縮寫。關于socks5協定可以參考維基百科的說明,有中文有英文的,在這裡就不贅述了:
- https://zh.m.wikipedia.org/zh-hans/SOCKS
- https://en.wikipedia.org/wiki/SOCKS#SOCKS5
直接上具體的代碼實作:
extern crate core;
use std::io::{Read, Write};
fn do_greeting(src_reader: &mut std::net::TcpStream,
src_writer: &mut std::net::TcpStream) -> Result<(), Box<dyn std::error::Error>> {
let mut buf: Vec<u8> = vec![0x00; 256];
// 讀一個byte
src_reader.read_exact(&mut buf[0..1])?;
// 判斷是否是socks5協定的版本号
if buf[0] != 0x05 {
panic!("unreachable!");
}
src_reader.read_exact(&mut buf[0..1])?;
let nauth = buf[0] as usize;
src_reader.read_exact(&mut buf[0..nauth])?;
// buf[0..nauth]) must contains 0x00
src_writer.write(&[0x05])?;
src_writer.write(&[0x00])?;
println!("greeting done");
Ok(())
}
// 解析出請求的目标位址
fn parse_dst(src_reader: &mut std::net::TcpStream) -> Result<String, Box<dyn std::error::Error>> {
let mut buf: Vec<u8> = vec![0x00; 256];
src_reader.read_exact(&mut buf[0..1])?;
// 判斷是否是socks5協定的版本号
if buf[0] != 0x05 {
panic!("unreachable!");
}
src_reader.read_exact(&mut buf[0..1])?;
if buf[0] != 0x01 {
// 不支援0x01以外的SOCK指令碼,0x01表示CONNECT請求
panic!("unreachable!");
}
src_reader.read_exact(&mut buf[0..1])?;
if buf[0] != 0x00 {
panic!("unreachable!");
}
src_reader.read_exact(&mut buf[0..1])?;
// 比對ATYP BND.ADDR類型
let host = match buf[0] {
0x01 => {
// IPv4位址,DST.ADDR部分4位元組長度
src_reader.read_exact(&mut buf[0..4])?;
std::net::Ipv4Addr::new(buf[0], buf[1], buf[2], buf[3]).to_string()
}
0x03 => {
// 域名,DST.ADDR部分第一個位元組為域名長度,DST.ADDR剩餘的内容為域名,沒有\0結尾
src_reader.read_exact(&mut buf[0..1])?;
let l = buf[0] as usize;
src_reader.read_exact(&mut buf[0..l])?;
String::from_utf8_lossy(&buf[0..l]).to_string() // example: baidu.com
}
0x04 => {
// IPv6位址,16個位元組長度
src_reader.read_exact(&mut buf[0..16])?;
std::net::Ipv6Addr::new(
((buf[0x00] as u16) << 8) | (buf[0x01] as u16),
((buf[0x02] as u16) << 8) | (buf[0x03] as u16),
((buf[0x04] as u16) << 8) | (buf[0x05] as u16),
((buf[0x06] as u16) << 8) | (buf[0x07] as u16),
((buf[0x08] as u16) << 8) | (buf[0x09] as u16),
((buf[0x0a] as u16) << 8) | (buf[0x0b] as u16),
((buf[0x0c] as u16) << 8) | (buf[0x0d] as u16),
((buf[0x0e] as u16) << 8) | (buf[0x0f] as u16),
).to_string()
}
_ => panic!("unreachable!")
};
src_reader.read_exact(&mut buf[0..2])?;
let port = ((buf[0] as u16) << 8) | (buf[1] as u16);
let dst = format!("{}:{}", host, port);
Ok(dst)
}
// socks5協定維基百科:https://zh.m.wikipedia.org/zh-hans/SOCKS
// 英文:https://en.wikipedia.org/wiki/SOCKS#SOCKS5
fn handle(src_stream: &std::net::TcpStream) -> Result<(), Box<dyn std::error::Error>> {
println!("src: {}", src_stream.peer_addr().unwrap());
let mut src_reader = src_stream.try_clone()?;
let mut src_writer = src_stream.try_clone()?;
do_greeting(&mut src_reader, &mut src_writer)?;
let dst = parse_dst(&mut src_reader)?;
println!("dst: {}", dst);
// 連接配接目标位址,轉發請求并傳回響應
let dst_stream = std::net::TcpStream::connect(&dst)?;
let mut dst_reader = dst_stream.try_clone()?;
let mut dst_writer = dst_stream.try_clone()?;
// 參考socks5對響應包的描述
// VER
src_writer.write(&[0x05])?;
// STATUS
src_writer.write(&[0x00])?;
// RSV
src_writer.write(&[0x00])?;
// BNDADDR
src_writer.write(&[0x01])?;
src_writer.write(&[0x00])?;
src_writer.write(&[0x00])?;
src_writer.write(&[0x00])?;
src_writer.write(&[0x00])?;
// BNDPORT
src_writer.write(&[0x00])?;
src_writer.write(&[0x00])?;
std::thread::spawn(move || {
std::io::copy(&mut src_reader, &mut dst_writer).ok();
});
std::io::copy(&mut dst_reader, &mut src_writer).ok();
Ok(())
}
fn main() {
let mut c_listen = String::from("127.0.0.1:1080");
{
let mut ap = argparse::ArgumentParser::new();
ap.set_description("Socks5 Proxy");
// 定義支援的參數
ap.refer(&mut c_listen).add_option(
&["-l", "--listen"], argparse::Store, "listen address",
);
ap.parse_args_or_exit();
}
println!("Listen and server on {}", c_listen);
// 開啟tcp監聽器
let listener = std::net::TcpListener::bind(c_listen.as_str()).unwrap();
for stream in listener.incoming() {
match stream {
Ok(data) => {
// 建立新的線程去處理請求
std::thread::spawn(move || {
if let Err(err) = handle(&data) {
println!("error: {:?}", err)
}
});
}
Err(err) => {
println!("error: {:?}", err);
}
}
}
}
上面的代碼用到了
argparse
這個庫來解析指令行參數,是以需要在
Cargo.toml
檔案需要增加如下依賴項:
[dependencies]
argparse = "0.2.2"
$ cargo build
$ socks5proxy -l 127.0.0.1:1080
$ curl --socks5-hostname 127.0.0.1:1080 baidu.com