From 262b89abb42c50c5000b44c1e54145ae5f5a7733 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?I=CC=87brahim=20Su=CC=88ren?= <ibrahimsn98@gmail.com>
Date: Mon, 3 Mar 2025 15:27:00 +0300
Subject: [PATCH] Implement tcp proxy with streaming example

---
 tcpproxy2/server.go | 121 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 121 insertions(+)
 create mode 100644 tcpproxy2/server.go

diff --git a/tcpproxy2/server.go b/tcpproxy2/server.go
new file mode 100644
index 0000000..54e1505
--- /dev/null
+++ b/tcpproxy2/server.go
@@ -0,0 +1,121 @@
+/*
+ * Copyright 2021 CloudWeGo
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"sync"
+	"time"
+
+	"github.com/cloudwego/netpoll"
+)
+
+var (
+	downstreamAddr = "127.0.0.1:8080"
+	downstreamKey  = "downstream"
+)
+
+func main() {
+	network, address := "tcp", ":8081"
+	listener, _ := netpoll.CreateListener(network, address)
+	eventLoop, _ := netpoll.NewEventLoop(
+		onRequest,
+		netpoll.WithOnConnect(onConnect),
+		netpoll.WithReadTimeout(time.Second),
+	)
+
+	// start listen loop ...
+	if err := eventLoop.Serve(listener); err != nil {
+		log.Fatal(err)
+	}
+}
+
+var _ netpoll.OnConnect = onConnect
+var _ netpoll.OnRequest = onRequest
+
+func onConnect(ctx context.Context, _ netpoll.Connection) context.Context {
+	downstream, err := netpoll.DialConnection("tcp", downstreamAddr, time.Second)
+	if err != nil {
+		log.Printf("connect downstream failed: %v", err)
+	}
+	return context.WithValue(ctx, downstreamKey, downstream)
+}
+
+func onRequest(ctx context.Context, upstream netpoll.Connection) error {
+	downstream := ctx.Value(downstreamKey).(netpoll.Connection)
+
+	var wg sync.WaitGroup
+	wg.Add(2)
+
+	go func() {
+		defer wg.Done()
+		transfer(ctx, upstream, downstream)
+	}()
+
+	go func() {
+		defer wg.Done()
+		transfer(ctx, downstream, upstream)
+	}()
+
+	wg.Wait()
+	if err := upstream.Close(); err != nil {
+		fmt.Printf("close downstream connection failed: %v", err)
+	}
+	if err := downstream.Close(); err != nil {
+		fmt.Printf("close downstream connection failed: %v", err)
+	}
+	return nil
+}
+
+func transfer(ctx context.Context, src netpoll.Connection, dst netpoll.Connection) {
+	reader := src.Reader()
+	writer := dst.Writer()
+
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		default:
+			buf, err := reader.ReadBinary(reader.Len())
+			if err != nil {
+				fmt.Printf("read stream failed: %v", err)
+				return
+			}
+
+			alloc, err := writer.Malloc(len(buf))
+			if err != nil {
+				fmt.Printf("malloc writer failed: %v", err)
+				return
+			}
+
+			copy(alloc, buf)
+
+			if writer.MallocLen() > 0 {
+				if err = writer.Flush(); err != nil {
+					fmt.Printf("flush writer error: %v", err)
+					return
+				}
+			}
+			if err = reader.Release(); err != nil {
+				fmt.Printf("release reader error: %v", err)
+				return
+			}
+		}
+	}
+}