From 8311d6e9709c974877320cd178759153684c2037 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E4=B8=96=E7=95=8C?= <i@sekai.icu>
Date: Fri, 22 Jul 2022 16:09:32 +0800
Subject: [PATCH] Improve 4in6 processing (break change)

---
 common/metadata/addr.go       | 41 ++++++++++++-----------------------
 common/metadata/serializer.go |  9 +++-----
 common/network/multi.go       |  4 ++--
 protocol/socks/handshake.go   |  2 +-
 4 files changed, 20 insertions(+), 36 deletions(-)

diff --git a/common/metadata/addr.go b/common/metadata/addr.go
index eb17a95..494b09f 100644
--- a/common/metadata/addr.go
+++ b/common/metadata/addr.go
@@ -22,11 +22,21 @@ func (ap Socksaddr) IsIP() bool {
 }
 
 func (ap Socksaddr) IsIPv4() bool {
-	return ap.Addr.Is4()
+	return ap.Addr.Is4() || ap.Addr.Is4In6()
 }
 
 func (ap Socksaddr) IsIPv6() bool {
-	return ap.Addr.Is6()
+	return ap.Addr.Is6() && !ap.Addr.Is4In6()
+}
+
+func (ap Socksaddr) Unwrap() Socksaddr {
+	if ap.Addr.Is4In6() {
+		return Socksaddr{
+			Addr: netip.AddrFrom4(ap.Addr.As4()),
+			Port: ap.Port,
+		}
+	}
+	return ap
 }
 
 func (ap Socksaddr) IsFqdn() bool {
@@ -88,25 +98,14 @@ func UDPAddr(ap netip.AddrPort) *net.UDPAddr {
 }
 
 func AddrPortFrom(ip net.IP, port uint16) netip.AddrPort {
-	addr, _ := netip.AddrFromSlice(ip)
-	return netip.AddrPortFrom(addr, port)
+	return netip.AddrPortFrom(AddrFromIP(ip), port)
 }
 
-func SocksaddrFrom(ip net.IP, port uint16) Socksaddr {
-	return SocksaddrFromNetIP(AddrPortFrom(ip, port))
-}
-
-func SocksaddrFromAddrPort(addr netip.Addr, port uint16) Socksaddr {
+func SocksaddrFrom(addr netip.Addr, port uint16) Socksaddr {
 	return SocksaddrFromNetIP(netip.AddrPortFrom(addr, port))
 }
 
 func SocksaddrFromNetIP(ap netip.AddrPort) Socksaddr {
-	if ap.Addr().Is4In6() {
-		return Socksaddr{
-			Addr: netip.AddrFrom4(ap.Addr().As4()),
-			Port: ap.Port(),
-		}
-	}
 	return Socksaddr{
 		Addr: ap.Addr(),
 		Port: ap.Port(),
@@ -163,17 +162,11 @@ func AddrPortFromNet(netAddr net.Addr) netip.AddrPort {
 
 func AddrFromIP(ip net.IP) netip.Addr {
 	addr, _ := netip.AddrFromSlice(ip)
-	if addr.Is4In6() {
-		addr = netip.AddrFrom4(addr.As4())
-	}
 	return addr
 }
 
 func ParseAddr(s string) netip.Addr {
 	addr, _ := netip.ParseAddr(s)
-	if addr.Is4In6() {
-		addr = netip.AddrFrom4(addr.As4())
-	}
 	return addr
 }
 
@@ -187,9 +180,6 @@ func ParseSocksaddr(address string) Socksaddr {
 
 func ParseSocksaddrHostPort(host string, port uint16) Socksaddr {
 	netAddr, err := netip.ParseAddr(host)
-	if netAddr.Is4In6() {
-		netAddr = netip.AddrFrom4(netAddr.As4())
-	}
 	if err != nil {
 		return Socksaddr{
 			Fqdn: host,
@@ -206,9 +196,6 @@ func ParseSocksaddrHostPort(host string, port uint16) Socksaddr {
 func ParseSocksaddrHostPortStr(host string, portStr string) Socksaddr {
 	port, _ := strconv.Atoi(portStr)
 	netAddr, err := netip.ParseAddr(host)
-	if netAddr.Is4In6() {
-		netAddr = netip.AddrFrom4(netAddr.As4())
-	}
 	if err != nil {
 		return Socksaddr{
 			Fqdn: host,
diff --git a/common/metadata/serializer.go b/common/metadata/serializer.go
index 1e7f934..6f7f54b 100644
--- a/common/metadata/serializer.go
+++ b/common/metadata/serializer.go
@@ -56,7 +56,7 @@ func (s *Serializer) WriteAddress(writer io.Writer, addr Socksaddr) error {
 		return err
 	}
 	if addr.Addr.IsValid() {
-		err = rw.WriteBytes(writer, addr.Addr.AsSlice())
+		err = rw.WriteBytes(writer, addr.Unwrap().Addr.AsSlice())
 	} else {
 		err = WriteSocksString(writer, addr.Fqdn)
 	}
@@ -129,11 +129,8 @@ func (s *Serializer) ReadAddress(reader io.Reader) (Socksaddr, error) {
 			if err != nil {
 				return Socksaddr{}, E.Cause(err, "read ipv6 address")
 			}
-			netAddr := netip.AddrFrom16(addr)
-			if netAddr.Is4In6() {
-				netAddr = netip.AddrFrom4(netAddr.As4())
-			}
-			return Socksaddr{Addr: netAddr}, nil
+
+			return Socksaddr{Addr: netip.AddrFrom16(addr)}.Unwrap(), nil
 		default:
 			return Socksaddr{}, E.New("unknown address family: ", af)
 		}
diff --git a/common/network/multi.go b/common/network/multi.go
index b2afc11..2649cd0 100644
--- a/common/network/multi.go
+++ b/common/network/multi.go
@@ -18,7 +18,7 @@ func DialSerial(ctx context.Context, dialer Dialer, network string, destination
 	var err error
 	var connErrors []error
 	for _, address := range destinationAddresses {
-		conn, err = dialer.DialContext(ctx, network, M.SocksaddrFromAddrPort(address, destination.Port))
+		conn, err = dialer.DialContext(ctx, network, M.SocksaddrFrom(address, destination.Port))
 		if err != nil {
 			connErrors = append(connErrors, err)
 			continue
@@ -33,7 +33,7 @@ func ListenSerial(ctx context.Context, dialer Dialer, destination M.Socksaddr, d
 	var err error
 	var connErrors []error
 	for _, address := range destinationAddresses {
-		conn, err = dialer.ListenPacket(ctx, M.SocksaddrFromAddrPort(address, destination.Port))
+		conn, err = dialer.ListenPacket(ctx, M.SocksaddrFrom(address, destination.Port))
 		if err != nil {
 			connErrors = append(connErrors, err)
 			continue
diff --git a/protocol/socks/handshake.go b/protocol/socks/handshake.go
index 5908a59..81869fb 100644
--- a/protocol/socks/handshake.go
+++ b/protocol/socks/handshake.go
@@ -112,7 +112,7 @@ func HandleConnection0(ctx context.Context, conn net.Conn, version byte, authent
 		case socks4.CommandConnect:
 			responseAddr := request.Destination
 			if !responseAddr.IsIPv4() {
-				responseAddr = M.SocksaddrFromAddrPort(netip.IPv4Unspecified(), responseAddr.Port)
+				responseAddr = M.SocksaddrFrom(netip.IPv4Unspecified(), responseAddr.Port)
 			}
 			err = socks4.WriteResponse(conn, socks4.Response{
 				ReplyCode:   socks4.ReplyCodeGranted,