From f22705be2c7189635ad1606f966296b587e25261 Mon Sep 17 00:00:00 2001
From: Brian Ma <312.dumas@163.com>
Date: Thu, 1 Sep 2022 17:46:19 +0800
Subject: [PATCH] Fix wechat protocol is not working if no obfs string is
 configured

---
 pkg/conns/wechat/obfs.go |  7 +++++--
 pkg/obfs/dummy.go        | 21 +++++++++++++++++++++
 pkg/transport/client.go  |  8 ++------
 pkg/transport/server.go  |  8 ++------
 4 files changed, 30 insertions(+), 14 deletions(-)
 create mode 100644 pkg/obfs/dummy.go

diff --git a/pkg/conns/wechat/obfs.go b/pkg/conns/wechat/obfs.go
index 99aa4a8..d601cd1 100644
--- a/pkg/conns/wechat/obfs.go
+++ b/pkg/conns/wechat/obfs.go
@@ -25,10 +25,13 @@ type ObfsWeChatUDPConn struct {
 	sn         uint32
 }
 
-func NewObfsWeChatUDPConn(orig *net.UDPConn, obfs obfs.Obfuscator) *ObfsWeChatUDPConn {
+func NewObfsWeChatUDPConn(orig *net.UDPConn, obfs_ obfs.Obfuscator) *ObfsWeChatUDPConn {
+	if obfs_ == nil {
+		obfs_ = obfs.NewDummyObfuscator()
+	}
 	return &ObfsWeChatUDPConn{
 		orig:     orig,
-		obfs:     obfs,
+		obfs:     obfs_,
 		readBuf:  make([]byte, udpBufferSize),
 		writeBuf: make([]byte, udpBufferSize),
 		sn:       rand.Uint32() & 0xFFFF,
diff --git a/pkg/obfs/dummy.go b/pkg/obfs/dummy.go
new file mode 100644
index 0000000..6899f3a
--- /dev/null
+++ b/pkg/obfs/dummy.go
@@ -0,0 +1,21 @@
+package obfs
+
+type DummyObfuscator struct{}
+
+func NewDummyObfuscator() *DummyObfuscator {
+	return &DummyObfuscator{}
+}
+
+func (x *DummyObfuscator) Deobfuscate(in []byte, out []byte) int {
+	pLen := len(in)
+	if pLen <= 0 || len(out) < pLen {
+		// Invalid
+		return 0
+	}
+	copy(out, in)
+	return pLen
+}
+
+func (x *DummyObfuscator) Obfuscate(in []byte, out []byte) int {
+	return copy(out, in)
+}
diff --git a/pkg/transport/client.go b/pkg/transport/client.go
index 6746ab9..4c03614 100644
--- a/pkg/transport/client.go
+++ b/pkg/transport/client.go
@@ -42,12 +42,8 @@ func (ct *ClientTransport) quicPacketConn(proto string, server string, obfs obfs
 		if err != nil {
 			return nil, err
 		}
-		if obfs != nil {
-			oc := wechat.NewObfsWeChatUDPConn(conn, obfs)
-			return oc, nil
-		} else {
-			return conn, nil
-		}
+		oc := wechat.NewObfsWeChatUDPConn(conn, obfs)
+		return oc, nil
 	} else if proto == "faketcp" {
 		var conn *faketcp.TCPConn
 		conn, err := faketcp.Dial("tcp", server)
diff --git a/pkg/transport/server.go b/pkg/transport/server.go
index 6c297ef..5685e81 100644
--- a/pkg/transport/server.go
+++ b/pkg/transport/server.go
@@ -101,12 +101,8 @@ func (st *ServerTransport) quicPacketConn(proto string, laddr string, obfs obfs.
 		if err != nil {
 			return nil, err
 		}
-		if obfs != nil {
-			oc := wechat.NewObfsWeChatUDPConn(conn, obfs)
-			return oc, nil
-		} else {
-			return conn, nil
-		}
+		oc := wechat.NewObfsWeChatUDPConn(conn, obfs)
+		return oc, nil
 	} else if proto == "faketcp" {
 		conn, err := faketcp.Listen("tcp", laddr)
 		if err != nil {