Refactor: autonomize core package

constant/constant.go

@@ -1,2 +0,0 @@
-// Package constant provides global constants/variables of this project.
-package constant

constant/metadata.go

@@ -0,0 +1,93 @@
+package constant
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"net"
+	"strconv"
+
+	"github.com/xjasonlyu/tun2socks/component/socks5"
+)
+
+const (
+	TCP Network = iota
+	UDP
+)
+
+type Network uint8
+
+func (n Network) String() string {
+	switch n {
+	case TCP:
+		return "tcp"
+	case UDP:
+		return "udp"
+	default:
+		return fmt.Sprintf("network(%d)", n)
+	}
+}
+
+func (n Network) MarshalText() ([]byte, error) {
+	return []byte(n.String()), nil
+}
+
+// Metadata implements the net.Addr interface.
+type Metadata struct {
+	Net     Network `json:"network"`
+	SrcIP   net.IP  `json:"sourceIP"`
+	MidIP   net.IP  `json:"dialerIP"`
+	DstIP   net.IP  `json:"destinationIP"`
+	SrcPort uint16  `json:"sourcePort"`
+	MidPort uint16  `json:"dialerPort"`
+	DstPort uint16  `json:"destinationPort"`
+}
+
+func (m *Metadata) DestinationAddress() string {
+	return net.JoinHostPort(m.DstIP.String(), strconv.FormatUint(uint64(m.DstPort), 10))
+}
+
+func (m *Metadata) SourceAddress() string {
+	return net.JoinHostPort(m.SrcIP.String(), strconv.FormatUint(uint64(m.SrcPort), 10))
+}
+
+func (m *Metadata) UDPAddr() *net.UDPAddr {
+	if m.Net != UDP || m.DstIP == nil {
+		return nil
+	}
+	return &net.UDPAddr{
+		IP:   m.DstIP,
+		Port: int(m.DstPort),
+	}
+}
+
+func (m *Metadata) SerializesSocksAddr() socks5.Addr {
+	var (
+		buf  [][]byte
+		port [2]byte
+	)
+	binary.BigEndian.PutUint16(port[:], m.DstPort)
+
+	if m.DstIP.To4() != nil /* IPv4 */ {
+		aType := socks5.AtypIPv4
+		buf = [][]byte{{aType}, m.DstIP.To4(), port[:]}
+	} else /* IPv6 */ {
+		aType := socks5.AtypIPv6
+		buf = [][]byte{{aType}, m.DstIP.To16(), port[:]}
+	}
+	return bytes.Join(buf, nil)
+}
+
+func (m *Metadata) Network() string {
+	return m.Net.String()
+}
+
+// String returns destination address of this metadata.
+// Also for implementing net.Addr interface.
+func (m *Metadata) String() string {
+	return m.DestinationAddress()
+}
+
+func (m *Metadata) Valid() bool {
+	return m.SrcIP != nil && m.DstIP != nil
+}