add -log option to redirect log , see issue #199

client/config.go

@@ -28,6 +28,7 @@ type Config struct {
 	NoCongestion int    `json:"nc"`
 	SockBuf      int    `json:"sockbuf"`
 	KeepAlive    int    `json:"keepalive"`
+	Log          string `json:"log"`
 }
 
 func parseJSONConfig(config *Config, path string) error {

client/main.go

@@ -61,16 +61,10 @@ func handleClient(p1, p2 io.ReadWriteCloser) {
 
 	// start tunnel
 	p1die := make(chan struct{})
-	go func() {
-		io.Copy(p1, p2)
-		close(p1die)
-	}()
+	go func() { io.Copy(p1, p2); close(p1die) }()
 
 	p2die := make(chan struct{})
-	go func() {
-		io.Copy(p2, p1)
-		close(p2die)
-	}()
+	go func() { io.Copy(p2, p1); close(p2die) }()
 
 	// wait for tunnel termination
 	select {
@@ -202,6 +196,11 @@ func main() {
 			Value:  10, // nat keepalive interval in seconds
 			Hidden: true,
 		},
+		cli.StringFlag{
+			Name:  "log",
+			Value: "",
+			Usage: "specify a log file to output, default goes to stderr",
+		},
 		cli.StringFlag{
 			Name:  "c",
 			Value: "", // when the value is not empty, the config path must exists
@@ -231,12 +230,21 @@ func main() {
 		config.NoCongestion = c.Int("nc")
 		config.SockBuf = c.Int("sockbuf")
 		config.KeepAlive = c.Int("keepalive")
+		config.Log = c.String("log")
 
 		if c.String("c") != "" {
 			err := parseJSONConfig(&config, c.String("c"))
 			checkError(err)
 		}
 
+		// log redirect
+		if config.Log != "" {
+			f, err := os.OpenFile(config.Log, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
+			checkError(err)
+			defer f.Close()
+			log.SetOutput(f)
+		}
+
 		switch config.Mode {
 		case "normal":
 			config.NoDelay, config.Interval, config.Resend, config.NoCongestion = 0, 30, 2, 1

server/config.go

@@ -26,6 +26,7 @@ type Config struct {
 	NoCongestion int    `json:"nc"`
 	SockBuf      int    `json:"sockbuf"`
 	KeepAlive    int    `json:"keepalive"`
+	Log          string `json:"log"`
 }
 
 func parseJSONConfig(config *Config, path string) error {

server/main.go

@@ -93,16 +93,10 @@ func handleClient(p1, p2 io.ReadWriteCloser) {
 
 	// start tunnel
 	p1die := make(chan struct{})
-	go func() {
-		io.Copy(p1, p2)
-		close(p1die)
-	}()
+	go func() { io.Copy(p1, p2); close(p1die) }()
 
 	p2die := make(chan struct{})
-	go func() {
-		io.Copy(p2, p1)
-		close(p2die)
-	}()
+	go func() { io.Copy(p2, p1); close(p2die) }()
 
 	// wait for tunnel termination
 	select {
@@ -224,6 +218,11 @@ func main() {
 			Value:  10, // nat keepalive interval in seconds
 			Hidden: true,
 		},
+		cli.StringFlag{
+			Name:  "log",
+			Value: "",
+			Usage: "specify a log file to output, default goes to stderr",
+		},
 		cli.StringFlag{
 			Name:  "c",
 			Value: "", // when the value is not empty, the config path must exists
@@ -251,6 +250,7 @@ func main() {
 		config.NoCongestion = c.Int("nc")
 		config.SockBuf = c.Int("sockbuf")
 		config.KeepAlive = c.Int("keepalive")
+		config.Log = c.String("log")
 
 		if c.String("c") != "" {
 			//Now only support json config file
@@ -258,6 +258,14 @@ func main() {
 			checkError(err)
 		}
 
+		// log redirect
+		if config.Log != "" {
+			f, err := os.OpenFile(config.Log, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
+			checkError(err)
+			defer f.Close()
+			log.SetOutput(f)
+		}
+
 		switch config.Mode {
 		case "normal":
 			config.NoDelay, config.Interval, config.Resend, config.NoCongestion = 0, 30, 2, 1