connect takes an existing connection to a socks5 proxy server, and commands the server to extend that connection to target, which must be a canonical address with a host and port.
(conn net.Conn, target string)
| 342 | // and commands the server to extend that connection to target, |
| 343 | // which must be a canonical address with a host and port. |
| 344 | func (s *proxy_socks5) connect(conn net.Conn, target string) error { |
| 345 | host, portStr, err := net.SplitHostPort(target) |
| 346 | if err != nil { |
| 347 | return err |
| 348 | } |
| 349 | |
| 350 | port, err := strconv.Atoi(portStr) |
| 351 | if err != nil { |
| 352 | return errors.New("proxy: failed to parse port number: " + portStr) |
| 353 | } |
| 354 | if port < 1 || port > 0xffff { |
| 355 | return errors.New("proxy: port number out of range: " + portStr) |
| 356 | } |
| 357 | |
| 358 | // the size here is just an estimate |
| 359 | buf := make([]byte, 0, 6+len(host)) |
| 360 | |
| 361 | buf = append(buf, proxy_socks5Version) |
| 362 | if len(s.user) > 0 && len(s.user) < 256 && len(s.password) < 256 { |
| 363 | buf = append(buf, 2 /* num auth methods */, proxy_socks5AuthNone, proxy_socks5AuthPassword) |
| 364 | } else { |
| 365 | buf = append(buf, 1 /* num auth methods */, proxy_socks5AuthNone) |
| 366 | } |
| 367 | |
| 368 | if _, err := conn.Write(buf); err != nil { |
| 369 | return errors.New("proxy: failed to write greeting to SOCKS5 proxy at " + s.addr + ": " + err.Error()) |
| 370 | } |
| 371 | |
| 372 | if _, err := io.ReadFull(conn, buf[:2]); err != nil { |
| 373 | return errors.New("proxy: failed to read greeting from SOCKS5 proxy at " + s.addr + ": " + err.Error()) |
| 374 | } |
| 375 | if buf[0] != 5 { |
| 376 | return errors.New("proxy: SOCKS5 proxy at " + s.addr + " has unexpected version " + strconv.Itoa(int(buf[0]))) |
| 377 | } |
| 378 | if buf[1] == 0xff { |
| 379 | return errors.New("proxy: SOCKS5 proxy at " + s.addr + " requires authentication") |
| 380 | } |
| 381 | |
| 382 | // See RFC 1929 |
| 383 | if buf[1] == proxy_socks5AuthPassword { |
| 384 | buf = buf[:0] |
| 385 | buf = append(buf, 1 /* password protocol version */) |
| 386 | buf = append(buf, uint8(len(s.user))) |
| 387 | buf = append(buf, s.user...) |
| 388 | buf = append(buf, uint8(len(s.password))) |
| 389 | buf = append(buf, s.password...) |
| 390 | |
| 391 | if _, err := conn.Write(buf); err != nil { |
| 392 | return errors.New("proxy: failed to write authentication request to SOCKS5 proxy at " + s.addr + ": " + err.Error()) |
| 393 | } |
| 394 | |
| 395 | if _, err := io.ReadFull(conn, buf[:2]); err != nil { |
| 396 | return errors.New("proxy: failed to read authentication reply from SOCKS5 proxy at " + s.addr + ": " + err.Error()) |
| 397 | } |
| 398 | |
| 399 | if buf[1] != 0 { |
| 400 | return errors.New("proxy: SOCKS5 proxy at " + s.addr + " rejected username/password") |
| 401 | } |