fix: correctly predict interface name on darwin

Old implementation didn't work if the interface to be created wasn't the biggest index.

For example if interfaces `bridge100` and `bridge102` already existed, vmnet would create a `bridge 101`,
but the old logic expected a `bridge103`.

Signed-off-by: Orzelius <albert.kostusev@siderolabs.com>

pkg/provision/providers/vm/network.go

@@ -5,39 +5,20 @@
 package vm
 
 import (
+	"errors"
 	"fmt"
-	"regexp"
-	"strconv"
-	"sync"
+	"slices"
 )
 
-var vmnetInterfaceRegex = sync.OnceValue(func() *regexp.Regexp { return regexp.MustCompile(`\bbridge(1\d\d)\b`) })
-
 // GetVmnetInterfaceName returns the name of the interface that will be assigned to the next vmnet interface.
 // The name is assigned incrementing by one, starting from "bridge100".
 func GetVmnetInterfaceName(allCurrentInterfaces []string) (string, error) {
-	vmnetInterfaceFound := false
-	largestVmnetIfIndex := 100
-
-	for _, iface := range allCurrentInterfaces {
-		matches := vmnetInterfaceRegex().FindSubmatch([]byte(iface))
-		if matches != nil {
-			vmnetInterfaceFound = true
-
-			index, err := strconv.Atoi(string(matches[1]))
-			if err != nil {
-				return "", fmt.Errorf("failed to parse interface name: %w", err)
-			}
-
-			if index > largestVmnetIfIndex {
-				largestVmnetIfIndex = index
-			}
+	for i := 100; i < 200; i++ {
+		interfaceName := fmt.Sprintf("bridge%d", i)
+		if slices.Index(allCurrentInterfaces, interfaceName) == -1 {
+			return interfaceName, nil
 		}
 	}
 
-	if !vmnetInterfaceFound {
-		return "bridge100", nil
-	}
-
-	return "bridge" + strconv.Itoa(largestVmnetIfIndex+1), nil
+	return "", errors.New("all interface names seem to be already in use")
 }

pkg/provision/providers/vm/network_test.go

@@ -24,7 +24,7 @@ func TestGetVmnetInterfaceNameNoVmnetInterface(t *testing.T) {
 
 func TestGetVmnetInterfaceNameWithExistingVmnetInterfaces(t *testing.T) {
 	interfaces := []string{
-		"bridge", "bridge1", "eth0", "utun1", "bridge001", "bridge1001", "bridge100", "bridge101",
+		"bridge", "bridge1", "eth0", "utun1", "bridge001", "bridge1001", "bridge100", "bridge101", "bridge104",
 	}
 	result, err := vm.GetVmnetInterfaceName(interfaces)
 	assert.NoError(t, err)