add packet connection adaptor

common/net/packetaddr/connection_adaptor.go

@@ -0,0 +1,100 @@
+package packetaddr
+
+import (
+	gonet "net"
+	"sync"
+	"time"
+
+	"github.com/v2fly/v2ray-core/v4/common"
+	"github.com/v2fly/v2ray-core/v4/common/buf"
+	"github.com/v2fly/v2ray-core/v4/common/errors"
+	"github.com/v2fly/v2ray-core/v4/common/net"
+	"github.com/v2fly/v2ray-core/v4/transport"
+)
+
+var errNotPacketConn = errors.New("not a packet connection")
+var errUnsupported = errors.New("unsupported action")
+
+func ToPacketAddrConn(link *transport.Link, dest net.Destination) (net.PacketConn, error) {
+	if !dest.Address.Family().IsDomain() {
+		return nil, errNotPacketConn
+	}
+	switch dest.Address.Domain() {
+	case seqPacketMagicAddress:
+		return &packetConnectionAdaptor{
+			readerAccess: &sync.Mutex{},
+			readerBuffer: nil,
+			link:         link,
+		}, nil
+	default:
+		return nil, errNotPacketConn
+	}
+}
+
+func CreatePacketAddrConn(link *transport.Link, isStream bool) (net.PacketConn, net.Destination, error) {
+	if isStream {
+		return nil, net.Destination{}, errUnsupported
+	}
+	return &packetConnectionAdaptor{
+			readerAccess: &sync.Mutex{},
+			readerBuffer: nil,
+			link:         link,
+		}, net.Destination{
+			Address: net.DomainAddress(seqPacketMagicAddress),
+			Port:    0,
+			Network: net.Network_UDP,
+		}, nil
+}
+
+type packetConnectionAdaptor struct {
+	readerAccess *sync.Mutex
+	readerBuffer buf.MultiBuffer
+	link         *transport.Link
+}
+
+func (c *packetConnectionAdaptor) ReadFrom(p []byte) (n int, addr gonet.Addr, err error) {
+	c.readerAccess.Lock()
+	defer c.readerAccess.Unlock()
+	if c.readerBuffer.IsEmpty() {
+		c.readerBuffer, err = c.link.Reader.ReadMultiBuffer()
+	}
+	c.readerBuffer, n = buf.SplitFirstBytes(c.readerBuffer, p)
+	p, addr = ExtractAddressFromPacket(p)
+	return
+}
+
+func (c *packetConnectionAdaptor) WriteTo(p []byte, addr gonet.Addr) (n int, err error) {
+	payloadLen := len(p)
+	p = AttachAddressToPacket(p, addr)
+	buffer := buf.New()
+	mb := buf.MultiBuffer{buffer}
+	err = c.link.Writer.WriteMultiBuffer(mb)
+	buf.ReleaseMulti(mb)
+	if err != nil {
+		return 0, err
+	}
+	return payloadLen, nil
+}
+
+func (c *packetConnectionAdaptor) Close() error {
+	c.readerAccess.Lock()
+	defer c.readerAccess.Unlock()
+	c.readerBuffer = buf.ReleaseMulti(c.readerBuffer)
+	return common.Interrupt(c.link)
+}
+
+func (c packetConnectionAdaptor) LocalAddr() gonet.Addr {
+	return &gonet.UnixAddr{Name: "unsupported"}
+}
+
+func (c packetConnectionAdaptor) SetDeadline(t time.Time) error {
+	return nil
+}
+
+func (c packetConnectionAdaptor) SetReadDeadline(t time.Time) error {
+	return nil
+}
+
+func (c packetConnectionAdaptor) SetWriteDeadline(t time.Time) error {
+	return nil
+}

common/net/packetaddr/packetaddr.go

@@ -5,7 +5,7 @@ import (
 	"github.com/v2fly/v2ray-core/v4/common/buf"
 	"github.com/v2fly/v2ray-core/v4/common/net"
 	"github.com/v2fly/v2ray-core/v4/common/protocol"
-	sysnet "net"
+	gonet "net"
 )
 
 var addrParser = protocol.NewAddressParser(
@@ -13,9 +13,9 @@ var addrParser = protocol.NewAddressParser(
 	protocol.AddressFamilyByte(0x02, net.AddressFamilyIPv6),
 )
 
-func AttachAddressToPacket(data []byte, address sysnet.Addr) []byte {
+func AttachAddressToPacket(data []byte, address gonet.Addr) []byte {
 	packetBuf := buf.StackNew()
-	udpaddr := address.(*sysnet.UDPAddr)
+	udpaddr := address.(*gonet.UDPAddr)
 	port, err := net.PortFromInt(uint32(udpaddr.Port))
 	if err != nil {
 		panic(err)
@@ -29,13 +29,13 @@ func AttachAddressToPacket(data []byte, address sysnet.Addr) []byte {
 	return data
 }
 
-func ExtractAddressFromPacket(data []byte) ([]byte, sysnet.Addr) {
+func ExtractAddressFromPacket(data []byte) ([]byte, gonet.Addr) {
 	packetBuf := buf.StackNew()
 	address, port, err := addrParser.ReadAddressPort(&packetBuf, bytes.NewReader(data))
 	if err != nil {
 		panic(err)
 	}
-	var addr = &sysnet.UDPAddr{
+	var addr = &gonet.UDPAddr{
 		IP:   address.IP(),
 		Port: int(port.Value()),
 		Zone: "",

common/net/packetaddr/special_address.go

@@ -0,0 +1,3 @@
+package packetaddr
+
+const seqPacketMagicAddress = "sp.packet-addr.v2fly.arpa"