packet header encoder decoder

common/net/packetaddr/packetaddr.go

@@ -0,0 +1,45 @@
+package packetaddr
+
+import (
+	"bytes"
+	"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"
+)
+
+var addrParser = protocol.NewAddressParser(
+	protocol.AddressFamilyByte(0x01, net.AddressFamilyIPv4),
+	protocol.AddressFamilyByte(0x02, net.AddressFamilyIPv6),
+)
+
+func AttachAddressToPacket(data []byte, address sysnet.Addr) []byte {
+	packetBuf := buf.StackNew()
+	udpaddr := address.(*sysnet.UDPAddr)
+	port, err := net.PortFromInt(uint32(udpaddr.Port))
+	if err != nil {
+		panic(err)
+	}
+	err = addrParser.WriteAddressPort(&packetBuf, net.IPAddress(udpaddr.IP), port)
+	if err != nil {
+		panic(err)
+	}
+	data = append(packetBuf.Bytes(), data...)
+	packetBuf.Release()
+	return data
+}
+
+func ExtractAddressFromPacket(data []byte) ([]byte, sysnet.Addr) {
+	packetBuf := buf.StackNew()
+	address, port, err := addrParser.ReadAddressPort(&packetBuf, bytes.NewReader(data))
+	if err != nil {
+		panic(err)
+	}
+	var addr = &sysnet.UDPAddr{
+		IP:   address.IP(),
+		Port: int(port.Value()),
+		Zone: "",
+	}
+	payload := data[int(packetBuf.Len()):]
+	return payload, addr
+}