add plugins

pkg/plugin/builtin/socks5.go

@@ -0,0 +1,167 @@
+package builtin
+
+import (
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+	"net"
+
+	"github.com/gotunnel/pkg/plugin"
+)
+
+const (
+	socks5Version = 0x05
+	noAuth        = 0x00
+	cmdConnect    = 0x01
+	atypIPv4      = 0x01
+	atypDomain    = 0x03
+	atypIPv6      = 0x04
+)
+
+// SOCKS5Plugin 将现有 SOCKS5 实现封装为 plugin
+type SOCKS5Plugin struct {
+	config map[string]string
+}
+
+// NewSOCKS5Plugin 创建 SOCKS5 plugin
+func NewSOCKS5Plugin() *SOCKS5Plugin {
+	return &SOCKS5Plugin{}
+}
+
+// Metadata 返回 plugin 信息
+func (p *SOCKS5Plugin) Metadata() plugin.PluginMetadata {
+	return plugin.PluginMetadata{
+		Name:        "socks5",
+		Version:     "1.0.0",
+		Type:        plugin.PluginTypeProxy,
+		Source:      plugin.PluginSourceBuiltin,
+		Description: "SOCKS5 proxy protocol handler (official plugin)",
+		Author:      "GoTunnel",
+		Capabilities: []string{
+			"dial", "read", "write", "close",
+		},
+	}
+}
+
+// Init 初始化 plugin
+func (p *SOCKS5Plugin) Init(config map[string]string) error {
+	p.config = config
+	return nil
+}
+
+// HandleConn 处理 SOCKS5 连接
+func (p *SOCKS5Plugin) HandleConn(conn net.Conn, dialer plugin.Dialer) error {
+	defer conn.Close()
+
+	// 握手阶段
+	if err := p.handshake(conn); err != nil {
+		return err
+	}
+
+	// 获取请求
+	target, err := p.readRequest(conn)
+	if err != nil {
+		return err
+	}
+
+	// 连接目标
+	remote, err := dialer.Dial("tcp", target)
+	if err != nil {
+		p.sendReply(conn, 0x05) // Connection refused
+		return err
+	}
+	defer remote.Close()
+
+	// 发送成功响应
+	if err := p.sendReply(conn, 0x00); err != nil {
+		return err
+	}
+
+	// 双向转发
+	go io.Copy(remote, conn)
+	io.Copy(conn, remote)
+
+	return nil
+}
+
+// Close 释放资源
+func (p *SOCKS5Plugin) Close() error {
+	return nil
+}
+
+// handshake 处理握手
+func (p *SOCKS5Plugin) handshake(conn net.Conn) error {
+	buf := make([]byte, 2)
+	if _, err := io.ReadFull(conn, buf); err != nil {
+		return err
+	}
+	if buf[0] != socks5Version {
+		return errors.New("unsupported SOCKS version")
+	}
+
+	nmethods := int(buf[1])
+	methods := make([]byte, nmethods)
+	if _, err := io.ReadFull(conn, methods); err != nil {
+		return err
+	}
+
+	// 响应：使用无认证
+	_, err := conn.Write([]byte{socks5Version, noAuth})
+	return err
+}
+
+// readRequest 读取请求
+func (p *SOCKS5Plugin) readRequest(conn net.Conn) (string, error) {
+	buf := make([]byte, 4)
+	if _, err := io.ReadFull(conn, buf); err != nil {
+		return "", err
+	}
+
+	if buf[0] != socks5Version || buf[1] != cmdConnect {
+		return "", errors.New("unsupported command")
+	}
+
+	var host string
+	switch buf[3] {
+	case atypIPv4:
+		ip := make([]byte, 4)
+		if _, err := io.ReadFull(conn, ip); err != nil {
+			return "", err
+		}
+		host = net.IP(ip).String()
+	case atypDomain:
+		lenBuf := make([]byte, 1)
+		if _, err := io.ReadFull(conn, lenBuf); err != nil {
+			return "", err
+		}
+		domain := make([]byte, lenBuf[0])
+		if _, err := io.ReadFull(conn, domain); err != nil {
+			return "", err
+		}
+		host = string(domain)
+	case atypIPv6:
+		ip := make([]byte, 16)
+		if _, err := io.ReadFull(conn, ip); err != nil {
+			return "", err
+		}
+		host = net.IP(ip).String()
+	default:
+		return "", errors.New("unsupported address type")
+	}
+
+	portBuf := make([]byte, 2)
+	if _, err := io.ReadFull(conn, portBuf); err != nil {
+		return "", err
+	}
+	port := binary.BigEndian.Uint16(portBuf)
+
+	return fmt.Sprintf("%s:%d", host, port), nil
+}
+
+// sendReply 发送响应
+func (p *SOCKS5Plugin) sendReply(conn net.Conn, rep byte) error {
+	reply := []byte{socks5Version, rep, 0x00, atypIPv4, 0, 0, 0, 0, 0, 0}
+	_, err := conn.Write(reply)
+	return err
+}