求助： tcp 连接转发

目前我做测试想做一个特殊的转发，A 代码运行在公网监听两个端口，一个是用户请求；另一个是 B 代码的请求连接。A 接受到请求后将用户的请求转发到 B ，目前表象一直卡在了 B 回传回去的问题上(没有对 B 请求成功是否验证)，请问各位大佬，这个如何操作

A 代码如下

package main import ( "fmt" "io" "net" "sync" ) var ( bConnMu sync.Mutex bConn net.Conn ) func handleUserRequest(userConn net.Conn) { defer func() { userConn.Close() fmt.Println("User connection closed") }() fmt.Println("Received user request") bConnMu.Lock() if bCOnn== nil { bConnMu.Unlock() fmt.Println("No connection to B machine") fmt.Fprintln(userConn, "No connection to B machine") return } bConnMu.Unlock() fmt.Println("Forwarding request to B machine") // 将用户请求转发给 B 机器 err := forwardRequest(userConn, bConn) if err != nil { fmt.Println("Error forwarding request to B machine:", err) return } fmt.Println("User request completed") } func forwardRequest(userConn, bConn net.Conn) error { done := make(chan error, 1) // 将用户请求转发给 B 机器 go func() { _, err := io.Copy(bConn, userConn) if err != nil { fmt.Println("Error forwarding request to B machine:", err) } else { fmt.Println("Finished forwarding request to B machine") } done <- err }() // 将 B 机器的响应转发给用户 go func() { _, err := io.Copy(userConn, bConn) if err != nil { fmt.Println("Error forwarding response to user:", err) } else { fmt.Println("Finished forwarding response to user") } done <- err }() err := <-done if err != nil { return err } err = <-done return err } func handleBConnection(conn net.Conn) { fmt.Println("B machine connected") bConnMu.Lock() if bConn != nil { bConn.Close() fmt.Println("Closed previous connection to B machine") } bCOnn= conn bConnMu.Unlock() // 监听 B 机器的断开连接 _, err := io.Copy(io.Discard, conn) if err != nil { fmt.Println("B machine disconnected with error:", err) } else { fmt.Println("B machine disconnected") } bConnMu.Lock() if bCOnn== conn { bCOnn= nil fmt.Println("Removed connection to B machine") } bConnMu.Unlock() conn.Close() } func main11() { // 启动监听用户代理请求的 goroutine fmt.Println("A machine listening for user requests on :12345") go func() { listener, err := net.Listen("tcp", ":12345") if err != nil { fmt.Println("Failed to listen for user requests:", err) return } defer listener.Close() for { conn, err := listener.Accept() if err != nil { fmt.Println("Failed to accept user request:", err) continue } go handleUserRequest(conn) } }() // 启动监听 B 机器连接的 goroutine fmt.Println("A machine listening for B machine connection on :12346") listener, err := net.Listen("tcp", ":12346") if err != nil { fmt.Println("Failed to listen for B machine connection:", err) return } defer listener.Close() for { conn, err := listener.Accept() if err != nil { fmt.Println("Failed to accept B machine connection:", err) continue } go handleBConnection(conn) } } 

B 代码如下

package main import ( "bufio" "fmt" "io" "log" "net" "net/http" "time" ) func handleTunnel(conn net.Conn) { defer func() { conn.Close() fmt.Println("Tunnel connection closed") }() fmt.Println("Handling new tunnel connection") reader := bufio.NewReader(conn) for { conn.SetReadDeadline(time.Now().Add(30 * time.Second)) request, err := http.ReadRequest(reader) if err != nil { if err == io.EOF { fmt.Println("A machine closed the connection") return } fmt.Println("Error reading request:", err) return } fmt.Printf("Received request from A machine: %s %s\n", request.Method, request.URL) if request.Method == http.MethodConnect { fmt.Printf("Processing CONNECT request: %s\n", request.URL.Host) targetConn, err := net.DialTimeout("tcp", request.URL.Host, 10*time.Second) if err != nil { log.Printf("Error connecting to target: %v\n", err) // 修改这里来手动发送 HTTP 响应 conn.Write([]byte("HTTP/1.1 503 Service Unavailable\r\n\r\n")) return } conn.Write([]byte("HTTP/1.1 200 Connection Established\r\n\r\n")) // 设置通道同步 goroutines done := make(chan struct{}) // 开启 goroutine 处理从 client 到目标主机的流量 go func() { io.Copy(targetConn, conn) // 假设 conn 是从 net.Listen 获取的连接 close(done) }() // 开启 goroutine 处理从目标主机到 client 的流量 go func() { io.Copy(conn, targetConn) close(done) }() // 等待至少一个方向的流完成 <-done targetConn.Close() conn.Close() } else { fmt.Printf("Processing normal request: %s\n", request.URL) // 处理普通请求 targetConn, err := net.DialTimeout("tcp", request.Host, 10*time.Second) if err != nil { fmt.Println("Error connecting to target host:", err) conn.Write([]byte("HTTP/1.1 503 Service Unavailable\r\n\r\n")) continue } defer func() { targetConn.Close() fmt.Printf("Target connection to %s closed\n", request.Host) }() fmt.Println("Connected to target host:", request.Host) // 将请求转发给目标主机 err = request.Write(targetConn) f err != nil { fmt.Println("Error forwarding request to target host:", err) conn.Write([]byte("HTTP/1.1 503 Service Unavailable\r\n\r\n")) continue } fmt.Println("Forwarded request to target host") // 将目标主机的响应转发给 A 机器 response, err := http.ReadResponse(bufio.NewReader(targetConn), request) if err != nil { fmt.Println("Error reading response from target host:", err) conn.Write([]byte("HTTP/1.1 503 Service Unavailable\r\n\r\n")) continue } fmt.Println("Read response from target host") err = response.Write(conn) if err != nil { fmt.Println("Error forwarding response to A machine:", err) continue } fmt.Println("Forwarded response to A machine") } } } func connectToA() { for { fmt.Println("Attempting to connect to A machine") conn, err := net.Dial("tcp", "A 机器地址:12346") if err != nil { fmt.Println("Failed to connect to A machine:", err) time.Sleep(5 * time.Second) continue } fmt.Println("Connected to A machine") // 发送心跳包 go func() { for { _, err := conn.Write([]byte("ping")) if err != nil { fmt.Println("Failed to send heartbeat:", err) conn.Close() return } time.Sleep(5 * time.Second) } }() handleTunnel(conn) } } func main() { go connectToA() select {} // 阻塞主线程 }