From f0d8923a9a864f70b658dd86e67feb373d8f879f Mon Sep 17 00:00:00 2001
From: Yawning Angel <yawning@schwanenlied.me>
Date: Sun, 25 May 2014 11:00:25 +0000
Subject: [PATCH] Move the SOCKS4 code off into it's own little getto.
Part of issue #7.
---
obfs4proxy/proxy_extras.go | 107 ------------------------
obfs4proxy/proxy_socks4.go | 164 +++++++++++++++++++++++++++++++++++++
2 files changed, 164 insertions(+), 107 deletions(-)
create mode 100644 obfs4proxy/proxy_socks4.go
diff --git a/obfs4proxy/proxy_extras.go b/obfs4proxy/proxy_extras.go
index 080e6b0..27b638b 100644
--- a/obfs4proxy/proxy_extras.go
+++ b/obfs4proxy/proxy_extras.go
@@ -28,11 +28,7 @@
package main
import (
- "errors"
- "io"
- "net"
"net/url"
- "strconv"
"code.google.com/p/go.net/proxy"
@@ -53,106 +49,3 @@ func getProxyDialer(uri *url.URL) (obfs4.DialFn, error) {
return dialer.Dial, nil
}
-
-// socks4 is a SOCKSv4 proxy.
-type socks4 struct {
- hostPort string
- username string
- forward proxy.Dialer
-}
-
-const (
- socks4Version = 0x04
- socks4CommandConnect = 0x01
- socks4Null = 0x00
- socks4ReplyVersion = 0x00
-
- socks4Granted = 0x5a
-)
-
-func newSOCKS4(uri *url.URL, forward proxy.Dialer) (proxy.Dialer, error) {
- s := new(socks4)
- s.hostPort = uri.Host
- s.forward = forward
- if uri.User != nil {
- s.username = uri.User.Username()
- }
- return s, nil
-}
-
-func (s *socks4) Dial(network, addr string) (net.Conn, error) {
- if network != "tcp" && network != "tcp4" {
- return nil, errors.New("invalid network type")
- }
-
- // Deal with the destination address/string.
- ipStr, portStr, err := net.SplitHostPort(addr)
- if err != nil {
- return nil, err
- }
- ip := net.ParseIP(ipStr)
- if ip == nil {
- return nil, errors.New("failed to parse destination IP")
- }
- ip4 := ip.To4()
- if ip4 == nil {
- return nil, errors.New("destination address is not IPv4")
- }
- port, err := strconv.ParseUint(portStr, 10, 16)
- if err != nil {
- return nil, err
- }
-
- // Connect to the proxy.
- c, err := s.forward.Dial("tcp", s.hostPort)
- if err != nil {
- return nil, err
- }
-
- // Make/write the request:
- // +----+----+----+----+----+----+----+----+----+----+....+----+
- // | VN | CD | DSTPORT | DSTIP | USERID |NULL|
- // +----+----+----+----+----+----+----+----+----+----+....+----+
-
- req := make([]byte, 0, 9+len(s.username))
- req = append(req, socks4Version)
- req = append(req, socks4CommandConnect)
- req = append(req, byte(port>>8), byte(port))
- req = append(req, ip4...)
- if s.username != "" {
- req = append(req, s.username...)
- }
- req = append(req, socks4Null)
- _, err = c.Write(req)
- if err != nil {
- c.Close()
- return nil, err
- }
-
- // Read the response:
- // +----+----+----+----+----+----+----+----+
- // | VN | CD | DSTPORT | DSTIP |
- // +----+----+----+----+----+----+----+----+
-
- var resp [8]byte
- _, err = io.ReadFull(c, resp[:])
- if err != nil {
- c.Close()
- return nil, err
- }
- if resp[0] != socks4ReplyVersion {
- c.Close()
- return nil, errors.New("proxy returned invalid SOCKS4 version")
- }
- if resp[1] != socks4Granted {
- c.Close()
- return nil, errors.New("proxy rejected the connect request")
- }
-
- return c, nil
-}
-
-func init() {
- // Despite the scheme name, this really is SOCKS4.
- proxy.RegisterDialerType("socks4a", newSOCKS4)
-}
diff --git a/obfs4proxy/proxy_socks4.go b/obfs4proxy/proxy_socks4.go
new file mode 100644
index 0000000..9d6bd4d
--- /dev/null
+++ b/obfs4proxy/proxy_socks4.go
@@ -0,0 +1,164 @@
+/*
+ * Copyright (c) 2014, Yawning Angel <yawning at torproject dot org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * * Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ * This is inspired by go.net/proxy/socks5.go:
+ *
+ * Copyright 2011 The Go Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style
+ * license that can be found in the LICENSE file.
+ */
+
+package main
+
+import (
+ "errors"
+ "fmt"
+ "io"
+ "net"
+ "net/url"
+ "strconv"
+
+ "code.google.com/p/go.net/proxy"
+)
+
+// socks4Proxy is a SOCKS4 proxy.
+type socks4Proxy struct {
+ hostPort string
+ username string
+ forward proxy.Dialer
+}
+
+const (
+ socks4Version = 0x04
+ socks4CommandConnect = 0x01
+ socks4Null = 0x00
+ socks4ReplyVersion = 0x00
+
+ socks4Granted = 0x5a
+ socks4Rejected = 0x5b
+ socks4RejectedIdentdFailed = 0x5c
+ socks4RejectedIdentdMismatch = 0x5d
+)
+
+func newSOCKS4(uri *url.URL, forward proxy.Dialer) (proxy.Dialer, error) {
+ s := new(socks4Proxy)
+ s.hostPort = uri.Host
+ s.forward = forward
+ if uri.User != nil {
+ s.username = uri.User.Username()
+ }
+ return s, nil
+}
+
+func (s *socks4Proxy) Dial(network, addr string) (net.Conn, error) {
+ if network != "tcp" && network != "tcp4" {
+ return nil, errors.New("invalid network type")
+ }
+
+ // Deal with the destination address/string.
+ ipStr, portStr, err := net.SplitHostPort(addr)
+ if err != nil {
+ return nil, err
+ }
+ ip := net.ParseIP(ipStr)
+ if ip == nil {
+ return nil, errors.New("failed to parse destination IP")
+ }
+ ip4 := ip.To4()
+ if ip4 == nil {
+ return nil, errors.New("destination address is not IPv4")
+ }
+ port, err := strconv.ParseUint(portStr, 10, 16)
+ if err != nil {
+ return nil, err
+ }
+
+ // Connect to the proxy.
+ c, err := s.forward.Dial("tcp", s.hostPort)
+ if err != nil {
+ return nil, err
+ }
+
+ // Make/write the request:
+ // +----+----+----+----+----+----+----+----+----+----+....+----+
+ // | VN | CD | DSTPORT | DSTIP | USERID |NULL|
+ // +----+----+----+----+----+----+----+----+----+----+....+----+
+
+ req := make([]byte, 0, 9+len(s.username))
+ req = append(req, socks4Version)
+ req = append(req, socks4CommandConnect)
+ req = append(req, byte(port>>8), byte(port))
+ req = append(req, ip4...)
+ if s.username != "" {
+ req = append(req, s.username...)
+ }
+ req = append(req, socks4Null)
+ _, err = c.Write(req)
+ if err != nil {
+ c.Close()
+ return nil, err
+ }
+
+ // Read the response:
+ // +----+----+----+----+----+----+----+----+
+ // | VN | CD | DSTPORT | DSTIP |
+ // +----+----+----+----+----+----+----+----+
+
+ var resp [8]byte
+ _, err = io.ReadFull(c, resp[:])
+ if err != nil {
+ c.Close()
+ return nil, err
+ }
+ if resp[0] != socks4ReplyVersion {
+ c.Close()
+ return nil, errors.New("proxy returned invalid SOCKS4 version")
+ }
+ if resp[1] != socks4Granted {
+ c.Close()
+ return nil, fmt.Errorf("proxy error: %s", socks4ErrorToString(resp[1]))
+ }
+
+ return c, nil
+}
+
+func socks4ErrorToString(code byte) string {
+ switch code {
+ case socks4Rejected:
+ return "request rejected or failed"
+ case socks4RejectedIdentdFailed:
+ return "request rejected becasue SOCKS server cannot connect to identd on the client"
+ case socks4RejectedIdentdMismatch:
+ return "request rejected because the client program and identd report different user-ids"
+ default:
+ return fmt.Sprintf("unknown failure code %x", code)
+ }
+}
+
+func init() {
+ // Despite the scheme name, this really is SOCKS4.
+ proxy.RegisterDialerType("socks4a", newSOCKS4)
+}
--
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