TUN-6586: Change ICMP proxy to only build for Darwin and use echo ID to track flows

ingress/icmp_darwin_test.go

@@ -0,0 +1,91 @@
+//go:build darwin
+
+package ingress
+
+import (
+	"math"
+	"net/netip"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestSingleEchoIDTracker(t *testing.T) {
+	tracker := newEchoIDTracker()
+	srcIP := netip.MustParseAddr("127.0.0.1")
+	echoID, ok := tracker.get(srcIP)
+	require.False(t, ok)
+	require.Equal(t, uint16(0), echoID)
+
+	// not assigned yet, so nothing to release
+	require.False(t, tracker.release(srcIP, echoID))
+
+	echoID, ok = tracker.assign(srcIP)
+	require.True(t, ok)
+	require.Equal(t, uint16(0), echoID)
+
+	echoID, ok = tracker.get(srcIP)
+	require.True(t, ok)
+	require.Equal(t, uint16(0), echoID)
+
+	// releasing a different ID returns false
+	require.False(t, tracker.release(srcIP, 1999))
+	require.True(t, tracker.release(srcIP, echoID))
+	// releasing the second time returns false
+	require.False(t, tracker.release(srcIP, echoID))
+
+	echoID, ok = tracker.get(srcIP)
+	require.False(t, ok)
+	require.Equal(t, uint16(0), echoID)
+
+	// Move to the next IP
+	echoID, ok = tracker.assign(srcIP)
+	require.True(t, ok)
+	require.Equal(t, uint16(1), echoID)
+}
+
+func TestFullEchoIDTracker(t *testing.T) {
+	tracker := newEchoIDTracker()
+	firstIP := netip.MustParseAddr("172.16.0.1")
+	srcIP := firstIP
+
+	for i := uint16(0); i < math.MaxUint16; i++ {
+		echoID, ok := tracker.assign(srcIP)
+		require.True(t, ok)
+		require.Equal(t, i, echoID)
+
+		echoID, ok = tracker.get(srcIP)
+		require.True(t, ok)
+		require.Equal(t, i, echoID)
+		srcIP = srcIP.Next()
+	}
+
+	// All echo IDs are assigned
+	echoID, ok := tracker.assign(srcIP.Next())
+	require.False(t, ok)
+	require.Equal(t, uint16(0), echoID)
+
+	srcIP = firstIP
+	for i := uint16(0); i < math.MaxUint16; i++ {
+		ok := tracker.release(srcIP, i)
+		require.True(t, ok)
+
+		echoID, ok = tracker.get(srcIP)
+		require.False(t, ok)
+		require.Equal(t, uint16(0), echoID)
+		srcIP = srcIP.Next()
+	}
+
+	// The IDs are assignable again
+	srcIP = firstIP
+	for i := uint16(0); i < math.MaxUint16; i++ {
+		echoID, ok := tracker.assign(srcIP)
+		require.True(t, ok)
+		require.Equal(t, i, echoID)
+
+		echoID, ok = tracker.get(srcIP)
+		require.True(t, ok)
+		require.Equal(t, i, echoID)
+		srcIP = srcIP.Next()
+	}
+}