正反向代理 Golang实现

痛定思痛。 2023-03-14 10:46 72阅读 0赞

**正向代理隐藏了真实客户端向服务器发送请求，反向代理隐藏了真实服务器向客户端提供服务。**

**正向代理:**

小王要结婚了，可是手上拿不出彩礼钱，他就找了好兄弟小张，小张同样没钱，但是小张认识思聪，于是小张从王思聪那里借到了20万交到了小王手上。对于思聪来说，他并不知道真正借钱的人是小王。

**常见例子：科学上网VPN**

**反向代理:**

小王结婚买房，他找到贷款中介，贷款中介给了他50万。但中介找哪个资方出资50万，小王完全不知情。

**常见例子：Nginx反向代理服务器**

**代理架构图如下所示**

**Golang示例代码**

server.go

type Server struct {
      listener net.Listener
    }
    
    func NewServer(address ...string) []*Server {
      s := make([]*Server, 0)
      for _, a := range address {
        lst, _ := net.Listen("tcp", a)
        s = append(s, &Server{
          listener: lst,
        })
      }
      return s
    }
    
    func (s *Server) Run() {
      for {
        conn, _ := s.listener.Accept() //服务器监听代理请求
        go s.handler(conn)
      }
    }
    
    func (s *Server) handler(conn net.Conn) {
      for {
        msg := make([]byte, 1024)
        _, _ = conn.Read(msg) //读取代理转发的客户端请求
        fmt.Println(string(msg))
        _, _ = conn.Write([]byte(fmt.Sprintf("message from Server: %s", s.listener.Addr().String()))) //服务器写入内容
      }
    }

agent.go

type Proxy struct {
      listener       net.Listener
      backendAddress string
    }
    
    func NewProxy(agentAddress, serverAddress string) *Proxy {
      lst, _ := net.Listen("tcp", agentAddress)
      return &Proxy{
        listener:       lst,
        backendAddress: serverAddress,
      }
    }
    
    func (p *Proxy) Run() {
      for {
        frontConn, _ := p.listener.Accept() //等待客户端请求
        backendConn, _ := net.Dial("tcp", p.backendAddress)
        go p.Agent(frontConn, backendConn)
      }
    }
    
    func (p *Proxy) Agent(frontConn, backendConn net.Conn) { //转发客户端请求与服务器返回
      go io.Copy(backendConn, frontConn)
      go io.Copy(frontConn, backendConn)
    }
    
    
    client.go
    
    type Client struct {
      conn net.Conn
    }
    
    func NewClient(proxyAddress string, num int) []*Client {
      c := make([]*Client, 0)
      for i := 0; i < num; i++ {
        conn, _ := net.Dial("tcp", proxyAddress)
        c = append(c, &Client{conn: conn})
      }
      return c
    }
    
    func (c *Client) Run() {
      //发起客户端请求
      _, _ = c.conn.Write([]byte(fmt.Sprintf("message from client: %s", c.conn.LocalAddr().String())))
      msg := make([]byte, 1024)
      //读取代理返回内容
      c.conn.Read(msg)
      fmt.Println(string(msg))
    }

client.go

type Client struct {
      conn net.Conn
    }
    
    func NewClient(proxyAddress string, num int) []*Client {
      c := make([]*Client, 0)
      for i := 0; i < num; i++ {
        conn, _ := net.Dial("tcp", proxyAddress)
        c = append(c, &Client{conn: conn})
      }
      return c
    }
    
    func (c *Client) Run() {
      //发起客户端请求
      _, _ = c.conn.Write([]byte(fmt.Sprintf("message from client: %s", c.conn.LocalAddr().String())))
      msg := make([]byte, 1024)
      //读取代理返回内容
      c.conn.Read(msg)
      fmt.Println(string(msg))
    }

main.go

func main() {
      servers := server.NewServer(":9998", ":9999") //开启本地9998和9999为服务器端口
      for _, s := range servers {
        go s.Run()
      }
    
      p := proxy.NewProxy(":9000", ":9999") //代理服务器端口9000，转发服务器端口9999
      go p.Run()
    
      for _, c := range client.NewClient(":9000", 3) { //客户端向9000代理端口发送请求
        go c.Run()
      }
      select {}

获取完整代码见Github地址：*https://github.com/slpslpslp/proxyDemo*

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