PR- Improved udp probe scalability

.github/workflows/basic-sanity.yml

@@ -20,5 +20,5 @@ jobs:
       - uses: actions/setup-go@v3
         with:
              go-version: '>=1.17.0'
-      - run: go test .
-      - run: go test -bench=.
+      - run: sudo go test .
+      - run: sudo go test -bench=.

lib_test.go

@@ -7,7 +7,6 @@ import (
 	"fmt"
 	"net"
 	"testing"
-
 	"github.com/loxilb-io/sctp"
 )
 
@@ -1036,4 +1035,10 @@ func TestProber(t *testing.T) {
 
 	sOk = L4ServiceProber("udp", "127.0.0.1:12234", "", "", "")
 	t.Logf("udp prober test2 %v\n", sOk)
+
+	sOk = L4ServiceProber("udp", "127.0.0.1:8080", "", "", "")
+	t.Logf("udp prober test3 %v\n", sOk)
+
+	sOk = L4ServiceProber("udp", "192.168.20.55:2234", "", "", "")
+	t.Logf("udp prober test4 %v\n\n\n", sOk)
 }

serviceprobe.go

@@ -12,11 +12,79 @@ import (
 	"golang.org/x/net/ipv4"
 	"net"
 	"net/http"
+	"os"
 	"strconv"
 	"strings"
+	"sync"
 	"time"
 )
 
+// SvcWait - Channel to wait for service reply
+type SvcWait struct {
+	wait chan bool
+}
+
+// SvcKey - Service Key
+type SvcKey struct {
+	Dst  string
+	Port int
+}
+
+var (
+	icmpRunner chan bool
+	svcLock    sync.RWMutex
+	svcs       map[SvcKey]*SvcWait
+)
+
+func waitForBoolChannelOrTimeout(ch <-chan bool, timeout time.Duration) (bool, bool) {
+	select {
+	case val := <-ch:
+		return val, true
+	case <-time.After(timeout):
+		return false, false
+	}
+}
+
+func listenForICMPUNreachable() {
+
+	// Open a raw socket to listen for ICMP messages
+	rc, err := icmp.ListenPacket("ip4:icmp", "0.0.0.0")
+	if err != nil {
+		os.Exit(1)
+	}
+	defer rc.Close()
+	pktData := make([]byte, 1500)
+	//rc.SetDeadline(time.Now().Add(5 * time.Second))
+	icmpRunner <- true
+	for {
+		plen, _, err := rc.ReadFrom(pktData)
+		if err != nil {
+			continue
+		}
+
+		icmpNr, err := icmp.ParseMessage(1, pktData)
+		if err != nil {
+			continue
+		}
+		if icmpNr.Code == 3 && plen >= 8+20+8 {
+			iph, err := ipv4.ParseHeader(pktData[8:])
+			if err != nil {
+				continue
+			}
+
+			if iph.Protocol == 17 {
+				dport := int(binary.BigEndian.Uint16(pktData[30:32]))
+				svcLock.Lock()
+				key := SvcKey{Dst: iph.Dst.String(), Port: dport}
+				if svcWait := svcs[key]; svcWait != nil {
+					svcWait.wait <- true
+				}
+				svcLock.Unlock()
+			}
+		}
+	}
+}
+
 // HTTPProber - Do a http probe for given url
 // returns true/false depending on whether probing was successful
 func HTTPProber(urls string) bool {
@@ -35,6 +103,16 @@ func HTTPProber(urls string) bool {
 // resp is the response expected from server (empty for none)
 // returns true/false depending on whether probing was successful
 func L4ServiceProber(sType string, sName string, sHint, req, resp string) bool {
+
+	svcLock.Lock()
+	if svcs == nil {
+		icmpRunner = make(chan bool)
+		svcs = map[SvcKey]*SvcWait{}
+		go listenForICMPUNreachable()
+		<-icmpRunner
+	}
+	svcLock.Unlock()
+
 	sOk := false
 	timeout := 1 * time.Second
 
@@ -145,47 +223,36 @@ func L4ServiceProber(sType string, sName string, sHint, req, resp string) bool {
 			return false
 		}
 	} else if sType == "udp" {
-		var lc net.ListenConfig
-		ctx, cancel := context.WithTimeout(context.Background(), time.Duration(3*time.Second))
-		defer cancel()
-		rc, err := lc.ListenPacket(ctx, "ip4:1", "0.0.0.0")
-		if err != nil {
-			return sOk
+
+		svcLock.Lock()
+		key := SvcKey{Dst: svcPair[0], Port: svcPort}
+		svcWait := svcs[key]
+		if svcWait == nil {
+			svcWait = &SvcWait{wait: make(chan bool)}
+			svcs[key] = svcWait
 		}
-		defer rc.Close()
+		svcLock.Unlock()
+
 		c.SetDeadline(time.Now().Add(1 * time.Second))
 		sOk = true
 		_, err = c.Write([]byte("probe"))
 		if err != nil {
 			return false
 		}
 		pktData := make([]byte, 1500)
-		rc.SetDeadline(time.Now().Add(1 * time.Second))
 		_, err = c.Read(pktData)
 		if err == nil {
 			return sOk
 		}
 
-		plen, _, err := rc.ReadFrom(pktData)
-		if err != nil {
-			return sOk
-		}
-		icmpNr, err := icmp.ParseMessage(1, pktData)
-		if err != nil {
-			return sOk
-		}
-		if icmpNr.Code == 3 && plen >= 8+20+8 {
-			iph, err := ipv4.ParseHeader(pktData[8:])
-			if err != nil {
-				return sOk
-			}
-			if iph.Dst.String() == svcPair[0] && iph.Protocol == 17 {
-				dport := int(binary.BigEndian.Uint16(pktData[30:32]))
-				if dport == svcPort {
-					sOk = false
-				}
-			}
+		_, unRch := waitForBoolChannelOrTimeout(svcWait.wait, 1*time.Second)
+		if unRch {
+			sOk = false
 		}
+
+		svcLock.Lock()
+		delete(svcs, key)
+		svcLock.Unlock()
 	}
 
 	return sOk