Ability to set fixed target

Makefile

@@ -11,4 +11,4 @@ build-ci:
 	cd ./build && tar -zcvf ./proxy-fix-linux-arm64.tar.gz ./proxy-fix-linux-arm64
 
 run:
-	env PORT=8080 NOHUP=1 go run . bun ./test/app.ts
+	env PORT=8080 NOHUP=1 TARGET=127.0.0.1:30000 go run . bun ./test/app.ts

README.md

@@ -10,7 +10,7 @@ Download from releases or build it and place it to `~/.local/bin/proxfix`.
 
 ```bash
 PROXYFIX=proxy-fix-linux-$( [ "$(uname -m)" = "aarch64" ] && echo "arm64" || echo "amd64" )
-wget https://github.com/domcloud/proxy-fix/releases/download/v0.2.3/$PROXYFIX.tar.gz
+wget https://github.com/domcloud/proxy-fix/releases/download/v0.2.4/$PROXYFIX.tar.gz
 tar -xf $PROXYFIX.tar.gz && mv $PROXYFIX /usr/local/bin/proxfix && rm -rf $PROXYFIX*
 ```
 

main.go

@@ -7,19 +7,24 @@ import (
 	"os"
 	"os/exec"
 	"strconv"
+	"strings"
 	"syscall"
 )
 
-var outPort int
+var outDial string
 
 func init() {
 	var err error
 	var pid int
 
-	outPort, pid, err = checkExistingProcess()
+	args := os.Args
+	bg := os.Getenv("NOHUP") == "1"
+	preferredDial := os.Getenv("TARGET")
+
+	outDial, pid, err = checkExistingProcess()
 	if err == nil {
-		if isPortListening(outPort) {
-			fmt.Printf("Process is already running on port %d\n", outPort)
+		if isPortListening(outDial) && outDial == preferredDial {
+			fmt.Printf("Process is already running on %d\n", outDial)
 			return
 		} else {
 			fmt.Printf("Killing stale process %d  \n", pid)
@@ -28,14 +33,15 @@ func init() {
 	}
 
 	// No existing process found or not listening, start a new one
-	outPort, err = getFreePort()
-	if err != nil {
-		panic("Can't get free port")
+	if preferredDial == "" {
+		outDial, err = getFreeDial()
+		if err != nil {
+			panic("Can't get free port")
+		}
+	} else {
+		outDial = preferredDial
 	}
 
-	args := os.Args
-	bg := os.Getenv("NOHUP") == "1"
-
 	// Check if there are additional arguments
 	if len(args) > 1 {
 		if bg {
@@ -50,7 +56,9 @@ func init() {
 				Pgid:    0,
 			}
 			cmd.Env = os.Environ()
-			cmd.Env = append(cmd.Env, fmt.Sprintf("PORT=%d", outPort))
+			if strings.HasPrefix(outDial, LOCAL_PREFIX) {
+				cmd.Env = append(cmd.Env, fmt.Sprintf("PORT=%s", outDial[len(LOCAL_PREFIX):]))
+			}
 			err = cmd.Run()
 			if err != nil {
 				fmt.Printf("Error starting command: %v\n", err)
@@ -65,14 +73,16 @@ func init() {
 				fmt.Printf("invalid PID of 0")
 				os.Exit(1)
 			}
-			writePidPortFile(pid, outPort)
+			writePidPortFile(pid, outDial)
 			fmt.Printf("Started process %s with PID %d in background\n", args[1], pid)
 		} else {
 			cmd := exec.Command(args[1], args[2:]...)
 			cmd.Stdout = os.Stdout
 			cmd.Stderr = os.Stderr
 			cmd.Env = os.Environ()
-			cmd.Env = append(cmd.Env, fmt.Sprintf("PORT=%d", outPort))
+			if strings.HasPrefix(outDial, LOCAL_PREFIX) {
+				cmd.Env = append(cmd.Env, fmt.Sprintf("PORT=%s", outDial[len(LOCAL_PREFIX):]))
+			}
 
 			// Start the specified command
 			err := cmd.Start()
@@ -100,7 +110,7 @@ func main() {
 
 func startProxy(address string) error {
 	proxy := Proxy{
-		DialTarget: fmt.Sprintf("localhost:%d", outPort),
+		DialTarget: outDial,
 	}
 	listener, err := net.Listen("tcp", address)
 	if err != nil {

util.go

@@ -15,16 +15,17 @@ import (
 
 const MAX_RETRY = 20
 const WAIT_RETRY = time.Second * 1
+const LOCAL_PREFIX = "127.0.0.1:"
 
 var invalidHeaderRegex = regexp.MustCompile("[^a-zA-Z0-9-]+")
 
-func getFreePort() (port int, err error) {
+func getFreeDial() (dial string, err error) {
 	var a *net.TCPAddr
 	if a, err = net.ResolveTCPAddr("tcp", "localhost:0"); err == nil {
 		var l *net.TCPListener
 		if l, err = net.ListenTCP("tcp", a); err == nil {
 			defer l.Close()
-			return l.Addr().(*net.TCPAddr).Port, nil
+			return fmt.Sprintf("%s%d", LOCAL_PREFIX, l.Addr().(*net.TCPAddr).Port), nil
 		}
 	}
 	return
@@ -42,31 +43,26 @@ func getPidFile() string {
 	return filepath.Join(os.Getenv("HOME"), "tmp", "app.pid")
 }
 
-func checkExistingProcess() (port int, pid int, err error) {
+func checkExistingProcess() (dial string, pid int, err error) {
 	data, err := os.ReadFile(getPidFile())
 	if err != nil {
-		return 0, 0, err
+		return "", 0, err
 	}
 
-	fields := strings.Split(string(data), ":")
-	if len(fields) != 2 {
-		return 0, 0, fmt.Errorf("invalid pid/port file format")
+	fields := strings.Split(string(data), ";")
+	if len(fields) != 2 || len(strings.Split(fields[1], ":")) < 2 {
+		return "", 0, fmt.Errorf("invalid pid/port file format")
 	}
 
 	pid, err = strconv.Atoi(fields[0])
 	if err != nil {
-		return 0, 0, fmt.Errorf("invalid PID format: %v", err)
-	}
-
-	port, err = strconv.Atoi(fields[1])
-	if err != nil {
-		return 0, 0, fmt.Errorf("invalid port format: %v", err)
+		return "", 0, fmt.Errorf("invalid PID format: %v", err)
 	}
 
 	if processExists(pid) {
-		return port, pid, nil
+		return fields[1], pid, nil
 	}
-	return 0, 0, fmt.Errorf("no running process found")
+	return "", 0, fmt.Errorf("no running process found")
 }
 
 func processExists(pid int) bool {
@@ -87,10 +83,10 @@ func processKill(pid int) bool {
 	return err == nil
 }
 
-func isPortListening(port int) bool {
+func isPortListening(dial string) bool {
 	retries := 0
 retry:
-	conn, err := net.Dial("tcp", fmt.Sprintf("127.0.0.1:%d", port))
+	conn, err := net.Dial("tcp", dial)
 	if err != nil {
 		if retries < MAX_RETRY {
 			retries += 1
@@ -105,8 +101,8 @@ retry:
 	return true
 }
 
-func writePidPortFile(pid, port int) {
-	err := os.WriteFile(getPidFile(), []byte(fmt.Sprintf("%d:%d", pid, port)), 0644)
+func writePidPortFile(pid int, dial string) {
+	err := os.WriteFile(getPidFile(), []byte(fmt.Sprintf("%d;%s", pid, dial)), 0644)
 	if err != nil {
 		fmt.Printf("Failed to write PID/port file: %v\n", err)
 	}