udp packet format in socks5

proxy/socks/protocol/udp.go

@@ -1,19 +1,59 @@
 package protocol
 
 import (
-	"io"
+	"encoding/binary"
+	"errors"
 
+	"github.com/v2ray/v2ray-core/common/log"
 	v2net "github.com/v2ray/v2ray-core/common/net"
 )
 
+var (
+	ErrorUnknownAddressType = errors.New("Unknown Address Type.")
+)
+
 type Socks5UDPRequest struct {
 	fragment byte
 	address  v2net.Address
 	data     []byte
 }
 
-func ReadUDPRequest(reader io.Reader) (request Socks5UDPRequest, err error) {
-	//buf := make([]byte, 4 * 1024) // Regular UDP packet size is 1500 bytes.
+func (request *Socks5UDPRequest) Destination() v2net.Destination {
+	return v2net.NewUDPDestination(request.address)
+}
+
+func ReadUDPRequest(packet []byte) (request Socks5UDPRequest, err error) {
+	// packet[0] and packet[1] are reserved
+	request.fragment = packet[2]
+
+	addrType := packet[3]
+	var dataBegin int
+
+	switch addrType {
+	case AddrTypeIPv4:
+		ip := packet[4:8]
+		port := binary.BigEndian.Uint16(packet[8:10])
+		request.address = v2net.IPAddress(ip, port)
+		dataBegin = 10
+	case AddrTypeIPv6:
+		ip := packet[4:20]
+		port := binary.BigEndian.Uint16(packet[20:22])
+		request.address = v2net.IPAddress(ip, port)
+		dataBegin = 22
+	case AddrTypeDomain:
+		domainLength := int(packet[4])
+		domain := string(packet[5 : 5+domainLength])
+		port := binary.BigEndian.Uint16(packet[5+domainLength : 5+domainLength+2])
+		request.address = v2net.DomainAddress(domain, port)
+		dataBegin = 5 + domainLength + 2
+	default:
+		log.Warning("Unknown address type %d", addrType)
+		err = ErrorUnknownAddressType
+		return
+	}
+
+	request.data = make([]byte, len(packet)-dataBegin)
+	copy(request.data, packet[dataBegin:])
 
 	return
 }