# SOCKS5 proxy

The SOCKS5 module in `src/socks5.rs` implements RFC 1928 (SOCKS5 protocol) and RFC 1929 (username/password authentication).

## Purpose

Handle the SOCKS5 handshake on the connector side, parse CONNECT requests, and resolve target addresses so that local applications can forward traffic through the tunnel.

## Supported features

- CONNECT command only (no BIND or UDP)
- No-auth and username/password authentication methods
- IPv4 and domain name targets (no IPv6)
- Target DNS resolution on the connector side

## Key abstractions

| Type | File | Description |
| ---- | ---- | ----------- |
| `Socks5Target` | `src/socks5.rs` | Enum: `Ipv4(addr, port)` or `Domain { domain, port }` |
| `Socks5State` | `src/socks5.rs` | State machine: ExpectGreeting → ExpectAuth → ExpectRequest → RequestReceived → Established → Closed |
| `Socks5Error` | `src/socks5.rs` | Error enum for malformed input, unsupported methods, and parse failures |
| `parse_greeting` | `src/socks5.rs` | Parse client greeting and choose auth method |
| `parse_auth_request` | `src/socks5.rs` | Parse username/password auth request |
| `parse_connect_request` | `src/socks5.rs` | Parse CONNECT request and extract target |
| `resolve_target` | `src/socks5.rs` | Async DNS resolution of a `Socks5Target` to a `SocketAddr` |

## Integration

The connector's `run_socks5_proxy` in `src/tunnel.rs` calls `socks5_handshake` (an async function in `src/tunnel.rs` that uses `src/socks5.rs` constants and helpers) for each incoming SOCKS5 connection. After handshake, it opens a stream via `StreamMux::open_stream` and forwards data bidirectionally.

## Key source files

| File | Purpose |
| ---- | ------- |
| `src/socks5.rs` | SOCKS5 protocol constants, parsing, target resolution |
| `src/tunnel.rs` | Async SOCKS5 handshake and proxy integration |