Return "" when NetDev.IpCIDR is empty

Signed-off-by: Jonathon Anderson <janderson@ciq.com>

internal/pkg/node/mergo.go

@@ -71,7 +71,7 @@ type Transformer struct{}
 func (t Transformer) Transformer(typ reflect.Type) func(dst, src reflect.Value) error {
 	if typ == reflect.TypeOf(net.IP{}) {
 		return func(dst, src reflect.Value) error {
-			if !src.IsValid() || src.IsZero() {
+			if !src.IsValid() || src.IsNil() {
 				return nil
 			}
 			dst.Set(src)

internal/pkg/node/methods.go

@@ -412,7 +412,7 @@ Return the ipv4 address and mask in CIDR format. Aimed for the use in
 templates.
 */
 func (netdev *NetDev) IpCIDR() string {
-	if netdev.Ipaddr.IsUnspecified() || netdev.Netmask.IsUnspecified() {
+	if netdev.Ipaddr == nil || netdev.Ipaddr.IsUnspecified() || netdev.Netmask == nil || netdev.Netmask.IsUnspecified() {
 		return ""
 	}
 	ipCIDR := net.IPNet{

internal/pkg/node/methods_test.go

@@ -7,6 +7,44 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
+func Test_IpCIDR(t *testing.T) {
+	tests := map[string]struct {
+		ipaddr  net.IP
+		netmask net.IP
+		cidr    string
+	}{
+		"nil": {
+			ipaddr:  nil,
+			netmask: nil,
+			cidr:    "",
+		},
+		"ip only": {
+			ipaddr:  net.ParseIP("192.168.1.1"),
+			netmask: nil,
+			cidr:    "",
+		},
+		"netmask only": {
+			ipaddr:  nil,
+			netmask: net.ParseIP("255.255.255.0"),
+			cidr:    "",
+		},
+		"working": {
+			ipaddr:  net.ParseIP("192.168.1.1"),
+			netmask: net.ParseIP("255.255.255.0"),
+			cidr:    "192.168.1.1/24",
+		},
+	}
+
+	for name, tt := range tests {
+		t.Run(name, func(t *testing.T) {
+			n := new(NetDev)
+			n.Ipaddr = tt.ipaddr
+			n.Netmask = tt.netmask
+			assert.Equal(t, tt.cidr, n.IpCIDR())
+		})
+	}
+}
+
 func Test_Empty(t *testing.T) {
 	var netdev NetDev
 	var netdevPtr *NetDev