fix: proxyDialer panic when domain name was not resolved

adapter/outbound/vmess.go

@@ -507,9 +507,9 @@ type vmessPacketConn struct {
 // WriteTo implments C.PacketConn.WriteTo
 // Since VMess doesn't support full cone NAT by design, we verify if addr matches uc.rAddr, and drop the packet if not.
 func (uc *vmessPacketConn) WriteTo(b []byte, addr net.Addr) (int, error) {
-	allowedAddr := uc.rAddr.(*net.UDPAddr)
-	destAddr := addr.(*net.UDPAddr)
-	if !(allowedAddr.IP.Equal(destAddr.IP) && allowedAddr.Port == destAddr.Port) {
+	allowedAddr := uc.rAddr
+	destAddr := addr
+	if allowedAddr.String() != destAddr.String() {
 		return 0, ErrUDPRemoteAddrMismatch
 	}
 	uc.access.Lock()

component/proxydialer/proxydialer.go

@@ -33,8 +33,8 @@ func NewByName(proxyName string, dialer C.Dialer) (C.Dialer, error) {
 }
 
 func (p proxyDialer) DialContext(ctx context.Context, network, address string) (net.Conn, error) {
-	currentMeta, err := addrToMetadata(address)
-	if err != nil {
+	currentMeta := &C.Metadata{Type: C.INNER}
+	if err := currentMeta.SetRemoteAddress(address); err != nil {
 		return nil, err
 	}
 	if strings.Contains(network, "udp") { // using in wireguard outbound
@@ -42,9 +42,14 @@ func (p proxyDialer) DialContext(ctx context.Context, network, address string) (
 		if err != nil {
 			return nil, err
 		}
-		return N.NewBindPacketConn(pc, currentMeta.UDPAddr()), nil
+		var rAddr net.Addr = currentMeta.UDPAddr()
+		if rAddr == nil { // the domain name was not resolved, will appear in not stream-oriented udp like Shadowsocks/Tuic
+			rAddr = N.NewCustomAddr("udp", currentMeta.RemoteAddress(), nil)
+		}
+		return N.NewBindPacketConn(pc, rAddr), nil
 	}
 	var conn C.Conn
+	var err error
 	if d, ok := p.dialer.(dialer.Dialer); ok { // first using old function to let mux work
 		conn, err = p.proxy.DialContext(ctx, currentMeta, dialer.WithOption(d.Opt))
 	} else {
@@ -60,8 +65,8 @@ func (p proxyDialer) DialContext(ctx context.Context, network, address string) (
 }
 
 func (p proxyDialer) ListenPacket(ctx context.Context, network, address string, rAddrPort netip.AddrPort) (net.PacketConn, error) {
-	currentMeta, err := addrToMetadata(rAddrPort.String())
-	if err != nil {
+	currentMeta := &C.Metadata{Type: C.INNER}
+	if err := currentMeta.SetRemoteAddress(address); err != nil {
 		return nil, err
 	}
 	return p.listenPacket(ctx, currentMeta)
@@ -84,27 +89,3 @@ func (p proxyDialer) listenPacket(ctx context.Context, currentMeta *C.Metadata)
 	}
 	return pc, nil
 }
-
-func addrToMetadata(rawAddress string) (addr *C.Metadata, err error) {
-	host, port, err := net.SplitHostPort(rawAddress)
-	if err != nil {
-		err = fmt.Errorf("addrToMetadata failed: %w", err)
-		return
-	}
-
-	if ip, err := netip.ParseAddr(host); err != nil {
-		addr = &C.Metadata{
-			Host:    host,
-			DstPort: port,
-		}
-	} else {
-		addr = &C.Metadata{
-			Host:    "",
-			DstIP:   ip.Unmap(),
-			DstPort: port,
-		}
-	}
-	addr.Type = C.INNER
-
-	return
-}

constant/metadata.go

@@ -229,3 +229,21 @@ func (m *Metadata) String() string {
 func (m *Metadata) Valid() bool {
 	return m.Host != "" || m.DstIP.IsValid()
 }
+
+func (m *Metadata) SetRemoteAddress(rawAddress string) error {
+	host, port, err := net.SplitHostPort(rawAddress)
+	if err != nil {
+		return err
+	}
+
+	if ip, err := netip.ParseAddr(host); err != nil {
+		m.Host = host
+		m.DstIP = netip.Addr{}
+	} else {
+		m.Host = ""
+		m.DstIP = ip.Unmap()
+	}
+	m.DstPort = port
+
+	return nil
+}

transport/tuic/conn.go

@@ -2,7 +2,6 @@ package tuic
 
 import (
 	"net"
-	"net/netip"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -216,11 +215,11 @@ func (q *quicStreamPacketConn) WriteTo(p []byte, addr net.Addr) (n int, err erro
 	}
 	buf := pool.GetBuffer()
 	defer pool.PutBuffer(buf)
-	addrPort, err := netip.ParseAddrPort(addr.String())
+	address, err := NewAddressNetAddr(addr)
 	if err != nil {
 		return
 	}
-	err = NewPacket(q.connId, uint16(len(p)), NewAddressAddrPort(addrPort), p).WriteTo(buf)
+	err = NewPacket(q.connId, uint16(len(p)), address, p).WriteTo(buf)
 	if err != nil {
 		return
 	}

transport/tuic/protocol.go

@@ -464,6 +464,18 @@ func NewAddress(metadata *C.Metadata) Address {
 	}
 }
 
+func NewAddressNetAddr(addr net.Addr) (Address, error) {
+	addrStr := addr.String()
+	if addrPort, err := netip.ParseAddrPort(addrStr); err == nil {
+		return NewAddressAddrPort(addrPort), nil
+	}
+	metadata := &C.Metadata{}
+	if err := metadata.SetRemoteAddress(addrStr); err != nil {
+		return Address{}, err
+	}
+	return NewAddress(metadata), nil
+}
+
 func NewAddressAddrPort(addrPort netip.AddrPort) Address {
 	var addrType byte
 	port := addrPort.Port()