first commit

README.md

@@ -1,3 +1,9 @@
 # portunnel
 
 A port forwarding tool with GoLang
+
+## Usage
+
+1. Compile the source code
+2. Configure like example config
+3. Run it!

config.json

@@ -0,0 +1,16 @@
+{
+  "forwardings": [
+    {
+      "local_address": "127.0.0.1",
+      "local_port": 9000,
+      "remote_address": "example.com",
+      "remote_port": 80
+    },
+    {
+      "local_address": "[::1]",
+      "local_port": 9001,
+      "remote_address": "example.com",
+      "remote_port": 80
+    }
+  ]
+}

go.mod

@@ -0,0 +1,7 @@
+module git.ghink.net/bigsk/portunnel
+
+go 1.18
+
+require github.com/fsnotify/fsnotify v1.6.0
+
+require golang.org/x/sys v0.0.0-20220908164124-27713097b956 // indirect

go.sum

@@ -0,0 +1,4 @@
+github.com/fsnotify/fsnotify v1.6.0 h1:n+5WquG0fcWoWp6xPWfHdbskMCQaFnG6PfBrh1Ky4HY=
+github.com/fsnotify/fsnotify v1.6.0/go.mod h1:sl3t1tCWJFWoRz9R8WJCbQihKKwmorjAbSClcnxKAGw=
+golang.org/x/sys v0.0.0-20220908164124-27713097b956 h1:XeJjHH1KiLpKGb6lvMiksZ9l0fVUh+AmGcm0nOMEBOY=
+golang.org/x/sys v0.0.0-20220908164124-27713097b956/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=

main.go

@@ -0,0 +1,185 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"net"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	"github.com/fsnotify/fsnotify"
+)
+
+type Config struct {
+	Forwardings []Forwarding `json:"forwardings"`
+}
+
+type Forwarding struct {
+	LocalAddress  string `json:"local_address"`
+	LocalPort     int    `json:"local_port"`
+	RemoteAddress string `json:"remote_address"`
+	RemotePort    int    `json:"remote_port"`
+}
+
+func main() {
+	// Read configuration file
+	configFile := "config.json"
+	config, err := readConfig(configFile)
+	if err != nil {
+		fmt.Printf("Failed to read config file: %v\n", err)
+		return
+	}
+
+	// Start forwarding task
+	for _, f := range config.Forwardings {
+		go runForwarding(f)
+	}
+
+	// Listen for configuration file changes
+	watcher, err := fsnotify.NewWatcher()
+	if err != nil {
+		fmt.Printf("Failed to create watcher: %v\n", err)
+		return
+	}
+	defer watcher.Close()
+
+	if err := watcher.Add(configFile); err != nil {
+		fmt.Printf("Failed to watch config file: %v\n", err)
+		return
+	}
+
+	sigCh := make(chan os.Signal, 1)
+	signal.Notify(sigCh, syscall.SIGINT, syscall.SIGTERM)
+
+	for {
+		select {
+		case event := <-watcher.Events:
+			if event.Op&fsnotify.Write == fsnotify.Write {
+				fmt.Printf("Config file changed, reloading...\n")
+
+				// Wait for the file system to complete the write operation
+				time.Sleep(100 * time.Millisecond)
+
+				// Re-read configuration file
+				newConfig, err := readConfig(configFile)
+				if err != nil {
+					fmt.Printf("Failed to read config file: %v\n", err)
+					continue
+				}
+
+				// Stop old forwarding task
+				for _, f := range config.Forwardings {
+					stopForwarding(f)
+				}
+
+				// Start a new forwarding task
+				for _, f := range newConfig.Forwardings {
+					go runForwarding(f)
+				}
+
+				config = newConfig
+			}
+		case err := <-watcher.Errors:
+			fmt.Printf("Watcher error: %v\n", err)
+		case sig := <-sigCh:
+			fmt.Printf("Received signal %v, shutting down...\n", sig)
+			// Stop all forwarding tasks
+			for _, f := range config.Forwardings {
+				stopForwarding(f)
+			}
+			return
+		}
+	}
+}
+
+func readConfig(filename string) (Config, error) {
+	file, err := os.Open(filename)
+	if err != nil {
+		return Config{}, err
+	}
+	defer file.Close()
+
+	config := Config{}
+	decoder := json.NewDecoder(file)
+	if err := decoder.Decode(&config); err != nil {
+		return Config{}, err
+	}
+
+	return config, nil
+}
+
+func runForwarding(f Forwarding) {
+	localAddr, err := net.ResolveTCPAddr("tcp", fmt.Sprintf("%s:%d", f.LocalAddress, f.LocalPort))
+	if err != nil {
+		fmt.Printf("Failed to resolve local address: %v\n", err)
+		return
+	}
+
+	remoteAddr, err := net.ResolveTCPAddr("tcp", fmt.Sprintf("%s:%d", f.RemoteAddress, f.RemotePort))
+	if err != nil {
+		fmt.Printf("Failed to resolve remote address: %v\n", err)
+		return
+	}
+	listener, err := net.ListenTCP("tcp", localAddr)
+	if err != nil {
+		fmt.Printf("Failed to listen on local address: %v\n", err)
+		return
+	}
+	defer listener.Close()
+
+	fmt.Printf("Started forwarding %s:%d to %s:%d\n", f.LocalAddress, f.LocalPort, f.RemoteAddress, f.RemotePort)
+
+	for {
+		conn, err := listener.Accept()
+		if err != nil {
+			fmt.Printf("Failed to accept connection: %v\n", err)
+			continue
+		}
+
+		go func() {
+			defer conn.Close()
+
+			remoteConn, err := net.DialTCP("tcp", nil, remoteAddr)
+			if err != nil {
+				fmt.Printf("Failed to connect to remote address: %v\n", err)
+				return
+			}
+			defer remoteConn.Close()
+
+			fmt.Printf("Forwarding %s -> %s\n", conn.RemoteAddr(), remoteConn.RemoteAddr())
+
+			// Forward data from a local connection to a remote connection
+			go copyConn(conn, remoteConn)
+
+			// Forward data from remote connections back to local connections
+			copyConn(remoteConn, conn)
+		}()
+	}
+}
+
+func stopForwarding(f Forwarding) {
+	conn, err := net.DialTCP("tcp", nil, &net.TCPAddr{
+		IP:   net.ParseIP(f.LocalAddress),
+		Port: f.LocalPort,
+	})
+	if err != nil {
+		fmt.Printf("Failed to stop forwarding %s:%d: %v\n", f.LocalAddress, f.LocalPort, err)
+		return
+	}
+	conn.Close()
+}
+
+func copyConn(src net.Conn, dst net.Conn) {
+	buf := make([]byte, 1024)
+	for {
+		n, err := src.Read(buf)
+		if err != nil {
+			return
+		}
+		if _, err := dst.Write(buf[:n]); err != nil {
+			return
+		}
+	}
+}