理论上,你可以使用Golang标准库(net包)来实现一个简单的SOCKS5服务器。简单的示例代码,演示如何使用Golang标准库创建一个SOCKS5服务器。
package main
import (
"fmt"
"net"
"io"
)
func handleRequest(conn net.Conn) {
// 读取版本和方法
buffer := make([]byte, 2)
_, err := conn.Read(buffer)
if err != nil {
fmt.Println("Failed to read version and method:", err)
conn.Close()
return
}
// 检查版本和方法是否为SOCKS5,并且方法数量大于0
if buffer[0] != 5 || int(buffer[1]) <= 0 {
fmt.Println("Invalid SOCKS version or method count")
conn.Close()
return
}
// 读取支持的认证方法
authMethods := make([]byte, buffer[1])
_, err = conn.Read(authMethods)
if err != nil {
fmt.Println("Failed to read authentication methods:", err)
conn.Close()
return
}
// 回复客户端,选择不需要认证
conn.Write([]byte{5, 0})
// 读取客户端请求
_, err = conn.Read(buffer[:2])
if err != nil {
fmt.Println("Failed to read request version and command:", err)
conn.Close()
return
}
// 检查请求版本和命令是否为SOCKS5,并且RSV字段是否为0
if buffer[0] != 5 || buffer[1] != 1 {
fmt.Println("Invalid request version or command")
conn.Close()
return
}
// 读取目标地址类型
_, err = conn.Read(buffer[:1])
if err != nil {
fmt.Println("Failed to read address type:", err)
conn.Close()
return
}
var host string
switch buffer[0] {
case 1: // IPv4地址
addr := make([]byte, 4)
_, err := conn.Read(addr)
if err != nil {
fmt.Println("Failed to read IPv4 address:", err)
conn.Close()
return
}
host = fmt.Sprintf("%d.%d.%d.%d", addr[0], addr[1], addr[2], addr[3])
case 3: // 域名
_, err := conn.Read(buffer[:1])
if err != nil {
fmt.Println("Failed to read domain length:", err)
conn.Close()
return
}
domainLength := int(buffer[0])
domainBytes := make([]byte, domainLength)
_, err = conn.Read(domainBytes)
if err != nil {
fmt.Println("Failed to read domain:", err)
conn.Close()
return
}
host = string(domainBytes)
case 4: // IPv6地址
ipv6Addr := make([]byte, 16)
_, err := conn.Read(ipv6Addr)
if err != nil {
fmt.Println("Failed to read IPv6 address:", err)
conn.Close()
return
}
host = net.IP(ipv6Addr).String()
default:
fmt.Println("Unsupported address type")
conn.Close()
return
}
// 读取目标端口
portBuffer := make([]byte, 2)
_, err = conn.Read(portBuffer)
if err != nil {
fmt.Println("Failed to read port:", err)
conn.Close()
return
}
port := int(portBuffer[0])<<8 + int(portBuffer[1])
// 响应客户端,表示连接建立成功
conn.Write([]byte{5, 0, 0, 1, 0, 0, 0, 0, 0, 0})
// 连接目标服务器
targetAddr := fmt.Sprintf("%s:%d", host, port)
targetConn, err := net.Dial("tcp", targetAddr)
if err != nil {
fmt.Println("Failed to connect to target:", err)
conn.Close()
return
}
defer targetConn.Close()
// 开始进行转发
go io.Copy(targetConn, conn)
io.Copy(conn, targetConn)
}
func main() {
listener, err := net.Listen("tcp", "127.0.0.1:1080")
if err != nil {
fmt.Println("Failed to start SOCKS5 server:", err)
return
}
defer listener.Close()
fmt.Println("SOCKS5 server listening on 127.0.0.1:1080")
for {
conn, err := listener.Accept()
if err != nil {
fmt.Println("Failed to accept connection:", err)
continue
}
go handleRequest(conn)
}
}
请注意,这只是一个简单的示例,可能需要根据你的实际需求进行修改和改进。此示例假设你的SOCKS5服务器不需要身份验证,并且只支持CONNECT命令。在实际的应用中,你可能需要根据需要进行身份验证,并支持其他命令。