Release all ressources on shutdown

config.go

@@ -39,6 +39,7 @@ func readConfig(dest string) {
 		}
 		if strings.HasPrefix(line, "responder") {
 			obj := configResponder{}
+			filter := ""
 			for {
 				scanner.Scan()
 				line = scanner.Text()
@@ -46,9 +47,10 @@ func readConfig(dest string) {
 					obj.Iface = strings.TrimSpace(strings.TrimPrefix(line, "iface"))
 				}
 				if strings.HasPrefix(line, "filter") {
-					obj.Filter = strings.TrimSpace(strings.TrimPrefix(line, "filter"))
+					filter += strings.TrimSpace(strings.TrimPrefix(line, "filter")) + ";"
 				}
 				if strings.HasPrefix(line, "}") {
+					obj.Filter = filter
 					break
 				}
 			}

main.go

@@ -6,28 +6,34 @@ import (
 )
 
 func main() {
-	fmt.Println("PNDPD Version 0.3 by Kioubit")
+	fmt.Println("PNDPD Version 0.4 by Kioubit")
+
+	if len(os.Args) <= 2 {
+		printUsage()
+		return
+	}
+
+	switch os.Args[1] {
+	case "respond":
+		if len(os.Args) == 4 {
+			go simpleRespond(os.Args[2], parseFilter(os.Args[3]))
+		} else {
+			go simpleRespond(os.Args[2], nil)
+		}
+	case "proxy":
+		go proxy(os.Args[2], os.Args[3])
+	case "readconfig":
+		readConfig(os.Args[2])
+	default:
+		printUsage()
+		return
+	}
+	waitForSignal()
+}
+
+func printUsage() {
+	fmt.Println("Specify command")
 	fmt.Println("Usage: pndpd readconfig <path to file>")
 	fmt.Println("Usage: pndpd respond <interface> <optional whitelist of CIDRs separated with a semicolon>")
 	fmt.Println("Usage: pndpd proxy <interface1> <interface2>")
-
-	if len(os.Args) <= 1 {
-		fmt.Println("Specify command")
-		os.Exit(1)
-	}
-	if os.Args[1] == "respond" {
-		if len(os.Args) == 4 {
-			simpleRespond(os.Args[2], parseFilter(os.Args[3]))
-		} else {
-			simpleRespond(os.Args[2], nil)
-		}
-	}
-	if os.Args[1] == "proxy" {
-		proxy(os.Args[2], os.Args[3])
-	}
-
-	if os.Args[1] == "readConfig" {
-		readConfig(os.Args[2])
-	}
-
 }

process.go

@@ -5,28 +5,63 @@ import (
 	"net"
 	"os"
 	"os/signal"
+	"runtime/pprof"
 	"strings"
+	"sync"
 	"syscall"
+	"time"
 )
 
 var GlobalDebug = false
 
+// Items needed for graceful shutdown
+var stop = make(chan struct{})
+var stopWg sync.WaitGroup
+var sigCh = make(chan os.Signal)
+
+func waitForSignal() {
+	signal.Notify(sigCh, os.Interrupt, syscall.SIGTERM)
+	<-sigCh
+	fmt.Println("Shutting down...")
+	close(stop)
+	if wgWaitTimout(&stopWg, 10*time.Second) {
+		fmt.Println("Done")
+	} else {
+		fmt.Println("Aborting shutdown, since it is taking too long")
+		pprof.Lookup("goroutine").WriteTo(os.Stdout, 1)
+	}
+
+	os.Exit(0)
+}
+
+func wgWaitTimout(wg *sync.WaitGroup, timeout time.Duration) bool {
+	t := make(chan struct{})
+	go func() {
+		defer close(t)
+		wg.Wait()
+	}()
+	select {
+	case <-t:
+		return true
+	case <-time.After(timeout):
+		return false
+	}
+}
+
 func simpleRespond(iface string, filter []*net.IPNet) {
+	defer stopWg.Done()
+	stopWg.Add(3) // This function, 2x goroutines
 	requests := make(chan *NDRequest, 100)
 	defer close(requests)
 	go respond(iface, requests, NDP_ADV, filter)
 	go listen(iface, requests, NDP_SOL)
-
-	sigCh := make(chan os.Signal)
-	signal.Notify(sigCh, os.Interrupt, syscall.SIGTERM)
-	select {
-	case <-sigCh:
-		fmt.Println("Exit")
-		os.Exit(0)
-	}
+	<-stop
 }
 
 func proxy(iface1, iface2 string) {
+	defer stopWg.Done()
+	stopWg.Add(9) // This function, 8x goroutines
+
 	req_iface1_sol_iface2 := make(chan *NDRequest, 100)
 	defer close(req_iface1_sol_iface2)
 	go listen(iface1, req_iface1_sol_iface2, NDP_SOL)
@@ -46,14 +81,7 @@ func proxy(iface1, iface2 string) {
 	defer close(req_iface2_adv_iface1)
 	go listen(iface2, req_iface2_adv_iface1, NDP_ADV)
 	go respond(iface1, req_iface2_adv_iface1, NDP_ADV, nil)
-
-	sigCh := make(chan os.Signal)
-	signal.Notify(sigCh, os.Interrupt, syscall.SIGTERM)
-	select {
-	case <-sigCh:
-		fmt.Println("Exit")
-		os.Exit(0)
-	}
+	<-stop
 }
 
 func parseFilter(f string) []*net.IPNet {

rawsocket.go

@@ -41,7 +41,6 @@ func htons(v uint16) int {
 func htons16(v uint16) uint16 { return v<<8 | v>>8 }
 
 func listen(iface string, responder chan *NDRequest, requestType NDPType) {
-
 	niface, err := net.InterfaceByName(iface)
 	if err != nil {
 		panic(err.Error())
@@ -55,7 +54,11 @@ func listen(iface string, responder chan *NDRequest, requestType NDPType) {
 	if err != nil {
 		fmt.Println(err.Error())
 	}
-	defer syscall.Close(fd)
+	go func() {
+		<-stop
+		syscall.Close(fd)
+		stopWg.Done() // syscall.read does not release when the file descriptor is closed
+	}()
 	fmt.Println("Obtained fd ", fd)
 
 	if len([]byte(iface)) > syscall.IFNAMSIZ {

responder.go

@@ -10,6 +10,7 @@ import (
 var globalFd int
 
 func respond(iface string, requests chan *NDRequest, respondType NDPType, filter []*net.IPNet) {
+	defer stopWg.Done()
 	fd, err := syscall.Socket(syscall.AF_INET6, syscall.SOCK_RAW, syscall.IPPROTO_RAW)
 	if err != nil {
 		panic(err)
@@ -46,7 +47,13 @@ func respond(iface string, requests chan *NDRequest, respondType NDPType, filter
 	}
 
 	for {
-		n := <-requests
+		var n *NDRequest
+		select {
+		case <-stop:
+			return
+		case n = <-requests:
+		}
+
 		if filter != nil {
 			ok := false
 			for _, i := range filter {