fix(network): use exact regex pattern in getTapIndex

pkg/network/network.go

@@ -67,9 +67,10 @@ func getTapIndex() (int, error) {
 	if err != nil {
 		return 0, err
 	}
+	tapRe := regexp.MustCompile(`^tap\d+(_urunc)?$`)
 	tapCount := 0
 	for _, iface := range ifaces {
-		if strings.Contains(iface.Name, "tap") {
+		if tapRe.MatchString(iface.Name) {
 			tapCount++
 		}
 	}

pkg/network/network_test.go

@@ -15,6 +15,7 @@
 package network
 
 import (
+	"regexp"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -56,3 +57,37 @@ func TestNewNetworkManager(t *testing.T) {
 		})
 	}
 }
+
+func TestGetTapIndex(t *testing.T) {
+	tapCount, err := getTapIndex()
+	assert.NoError(t, err, "getTapIndex() should not error")
+	assert.GreaterOrEqual(t, tapCount, 0, "tapCount should be >= 0")
+}
+
+func TestTapDeviceRegexMatching(t *testing.T) {
+	tapRe := regexp.MustCompile(`^tap\d+(_urunc)?$`)
+
+	tests := []struct {
+		ifaceName   string
+		shouldMatch bool
+	}{
+		{"tap0_urunc", true},
+		{"tap1_urunc", true},
+		{"tap0", true},
+		{"tap12", true},
+		{"vtap0", false},
+		{"cni-tap0", false},
+		{"bootstrap0", false},
+		{"stape0", false},
+		{"tap-master", false},
+		{"eth0", false},
+		{"lo", false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.ifaceName, func(t *testing.T) {
+			matched := tapRe.MatchString(tt.ifaceName)
+			assert.Equal(t, tt.shouldMatch, matched, "interface name %s match expectation failed", tt.ifaceName)
+		})
+	}
+}