From a689eb3bc4b53af70390acc3cf68c9f549b6b8d6 Mon Sep 17 00:00:00 2001 From: Michel Lespinasse Date: Sat, 21 Jan 2017 00:53:43 -0800 Subject: [PATCH] proxy: split SOCKS5 Dial method in two Split off a new SOCKS5 connect() method from Dial. connect() takes an existing connection to a socks5 server, and commands the server to extend that connection to a given target address and port. Change-Id: I5dbba58a67a0d884bda3d3ac194dc18bdebe74ab Reviewed-on: https://go-review.googlesource.com/36643 Reviewed-by: Adam Langley Reviewed-by: Brad Fitzpatrick --- proxy/socks5.go | 59 ++++++++++++++++++++++++++----------------------- 1 file changed, 31 insertions(+), 28 deletions(-) diff --git a/proxy/socks5.go b/proxy/socks5.go index 9b962823..973f57f1 100644 --- a/proxy/socks5.go +++ b/proxy/socks5.go @@ -72,24 +72,28 @@ func (s *socks5) Dial(network, addr string) (net.Conn, error) { if err != nil { return nil, err } - closeConn := &conn - defer func() { - if closeConn != nil { - (*closeConn).Close() - } - }() - - host, portStr, err := net.SplitHostPort(addr) - if err != nil { + if err := s.connect(conn, addr); err != nil { + conn.Close() return nil, err } + return conn, nil +} + +// 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. +func (s *socks5) connect(conn net.Conn, target string) error { + host, portStr, err := net.SplitHostPort(target) + if err != nil { + return err + } port, err := strconv.Atoi(portStr) if err != nil { - return nil, errors.New("proxy: failed to parse port number: " + portStr) + return errors.New("proxy: failed to parse port number: " + portStr) } if port < 1 || port > 0xffff { - return nil, errors.New("proxy: port number out of range: " + portStr) + return errors.New("proxy: port number out of range: " + portStr) } // the size here is just an estimate @@ -103,17 +107,17 @@ func (s *socks5) Dial(network, addr string) (net.Conn, error) { } if _, err := conn.Write(buf); err != nil { - return nil, errors.New("proxy: failed to write greeting to SOCKS5 proxy at " + s.addr + ": " + err.Error()) + return errors.New("proxy: failed to write greeting to SOCKS5 proxy at " + s.addr + ": " + err.Error()) } if _, err := io.ReadFull(conn, buf[:2]); err != nil { - return nil, errors.New("proxy: failed to read greeting from SOCKS5 proxy at " + s.addr + ": " + err.Error()) + return errors.New("proxy: failed to read greeting from SOCKS5 proxy at " + s.addr + ": " + err.Error()) } if buf[0] != 5 { - return nil, errors.New("proxy: SOCKS5 proxy at " + s.addr + " has unexpected version " + strconv.Itoa(int(buf[0]))) + return errors.New("proxy: SOCKS5 proxy at " + s.addr + " has unexpected version " + strconv.Itoa(int(buf[0]))) } if buf[1] == 0xff { - return nil, errors.New("proxy: SOCKS5 proxy at " + s.addr + " requires authentication") + return errors.New("proxy: SOCKS5 proxy at " + s.addr + " requires authentication") } if buf[1] == socks5AuthPassword { @@ -125,15 +129,15 @@ func (s *socks5) Dial(network, addr string) (net.Conn, error) { buf = append(buf, s.password...) if _, err := conn.Write(buf); err != nil { - return nil, errors.New("proxy: failed to write authentication request to SOCKS5 proxy at " + s.addr + ": " + err.Error()) + return errors.New("proxy: failed to write authentication request to SOCKS5 proxy at " + s.addr + ": " + err.Error()) } if _, err := io.ReadFull(conn, buf[:2]); err != nil { - return nil, errors.New("proxy: failed to read authentication reply from SOCKS5 proxy at " + s.addr + ": " + err.Error()) + return errors.New("proxy: failed to read authentication reply from SOCKS5 proxy at " + s.addr + ": " + err.Error()) } if buf[1] != 0 { - return nil, errors.New("proxy: SOCKS5 proxy at " + s.addr + " rejected username/password") + return errors.New("proxy: SOCKS5 proxy at " + s.addr + " rejected username/password") } } @@ -150,7 +154,7 @@ func (s *socks5) Dial(network, addr string) (net.Conn, error) { buf = append(buf, ip...) } else { if len(host) > 255 { - return nil, errors.New("proxy: destination hostname too long: " + host) + return errors.New("proxy: destination hostname too long: " + host) } buf = append(buf, socks5Domain) buf = append(buf, byte(len(host))) @@ -159,11 +163,11 @@ func (s *socks5) Dial(network, addr string) (net.Conn, error) { buf = append(buf, byte(port>>8), byte(port)) if _, err := conn.Write(buf); err != nil { - return nil, errors.New("proxy: failed to write connect request to SOCKS5 proxy at " + s.addr + ": " + err.Error()) + return errors.New("proxy: failed to write connect request to SOCKS5 proxy at " + s.addr + ": " + err.Error()) } if _, err := io.ReadFull(conn, buf[:4]); err != nil { - return nil, errors.New("proxy: failed to read connect reply from SOCKS5 proxy at " + s.addr + ": " + err.Error()) + return errors.New("proxy: failed to read connect reply from SOCKS5 proxy at " + s.addr + ": " + err.Error()) } failure := "unknown error" @@ -172,7 +176,7 @@ func (s *socks5) Dial(network, addr string) (net.Conn, error) { } if len(failure) > 0 { - return nil, errors.New("proxy: SOCKS5 proxy at " + s.addr + " failed to connect: " + failure) + return errors.New("proxy: SOCKS5 proxy at " + s.addr + " failed to connect: " + failure) } bytesToDiscard := 0 @@ -184,11 +188,11 @@ func (s *socks5) Dial(network, addr string) (net.Conn, error) { case socks5Domain: _, err := io.ReadFull(conn, buf[:1]) if err != nil { - return nil, errors.New("proxy: failed to read domain length from SOCKS5 proxy at " + s.addr + ": " + err.Error()) + return errors.New("proxy: failed to read domain length from SOCKS5 proxy at " + s.addr + ": " + err.Error()) } bytesToDiscard = int(buf[0]) default: - return nil, errors.New("proxy: got unknown address type " + strconv.Itoa(int(buf[3])) + " from SOCKS5 proxy at " + s.addr) + return errors.New("proxy: got unknown address type " + strconv.Itoa(int(buf[3])) + " from SOCKS5 proxy at " + s.addr) } if cap(buf) < bytesToDiscard { @@ -197,14 +201,13 @@ func (s *socks5) Dial(network, addr string) (net.Conn, error) { buf = buf[:bytesToDiscard] } if _, err := io.ReadFull(conn, buf); err != nil { - return nil, errors.New("proxy: failed to read address from SOCKS5 proxy at " + s.addr + ": " + err.Error()) + return errors.New("proxy: failed to read address from SOCKS5 proxy at " + s.addr + ": " + err.Error()) } // Also need to discard the port number if _, err := io.ReadFull(conn, buf[:2]); err != nil { - return nil, errors.New("proxy: failed to read port from SOCKS5 proxy at " + s.addr + ": " + err.Error()) + return errors.New("proxy: failed to read port from SOCKS5 proxy at " + s.addr + ": " + err.Error()) } - closeConn = nil - return conn, nil + return nil }