Initial import

cmd/protoproxy/main.go

@@ -0,0 +1,89 @@
+package main
+
+import (
+	"context"
+	"flag"
+	"io"
+	"log"
+	"net"
+	"sync"
+	"time"
+
+	"git.maze.io/go/dpi/protocol"
+)
+
+func main() {
+	listenFlag := flag.String("listen", "localhost:4080", "proxy listen address")
+	targetFlag := flag.String("target", "localhost:22", "proxy target address")
+	flag.Parse()
+
+	l, err := net.Listen("tcp", *listenFlag)
+	if err != nil {
+		log.Fatalf("listen error: %v", err)
+	}
+
+	log.Printf("listening on %s", l.Addr())
+	for {
+		c, err := l.Accept()
+		if err != nil {
+			log.Fatalln("accept error:", err)
+		}
+		go proxy(c, *targetFlag)
+	}
+}
+
+func proxy(client net.Conn, target string) {
+	log.Printf("new connection from %s", client.RemoteAddr())
+
+	// Hangup client if we return
+	defer func() {
+		log.Printf("closing connection to %s: %v", client.RemoteAddr(), client.Close())
+	}()
+
+	log.Printf("dialing %s", target)
+
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	var dialer net.Dialer
+
+	server, err := dialer.DialContext(ctx, "tcp", target)
+	if err != nil {
+		cancel()
+		log.Printf("error connecting to %s: %v", target, err)
+		return
+	}
+	cancel()
+
+	// Hangup server if we return
+	defer func() {
+		log.Printf("closing connection to %s: %v", server.RemoteAddr(), server.Close())
+	}()
+
+	// Setup interceptor and wrap the client and server connections.
+	interceptor := protocol.NewInterceptor()
+	client = interceptor.Client(client)
+	server = interceptor.Server(server)
+
+	// Request a return channel and start the detection before doing anything
+	// else with the client and server connections.
+	intercepted := interceptor.Detect(10 * time.Second)
+
+	log.Printf("client %s connected to %s; proxying", client.RemoteAddr(), server.RemoteAddr())
+
+	// Create a wait group and copy between client and server bidirectionally,
+	// either side needs to generate data for the detection to work.
+	var group sync.WaitGroup
+	group.Go(func() { io.Copy(client, server) })
+	group.Go(func() { io.Copy(server, client) })
+
+	// Wait until the interceptor produces data.
+	result := <-intercepted
+	if result.Error != nil {
+		log.Printf("protocol detection failed: %v", result.Error)
+	} else {
+		log.Printf("detected protocol %s version %s initiated by %s",
+			result.Protocol.Name, result.Protocol.Version, result.Direction)
+	}
+
+	// Wait for the multiplexing to finish.
+	group.Wait()
+}