template: dont truncate IPv6 zone identifiers in stripDomain

Signed-off-by: Jyotirmoy Roy <jyotirmoyroy649@gmail.com>

template/template.go

@@ -22,6 +22,7 @@ import (
 	"maps"
 	"math"
 	"net"
+	"net/netip"
 	"net/url"
 	"sort"
 	"strings"
@@ -191,8 +192,7 @@ func NewTemplateExpander(
 				if err != nil {
 					host = hostPort
 				}
-				ip := net.ParseIP(host)
-				if ip != nil {
+				if _, err := netip.ParseAddr(host); err == nil {
 					return hostPort
 				}
 				host = strings.Split(host, ".")[0]

template/template_test.go

@@ -584,6 +584,21 @@ func TestTemplateExpansion(t *testing.T) {
 			text:   "{{ \"[2001:0DB8::1]::12345\" | stripDomain }}",
 			output: "[2001:0DB8::1]::12345",
 		},
+		{
+			// IPv6 address with a zone identifier containing dots.
+			text:   "{{ \"fe80::1%eth0.100\" | stripDomain }}",
+			output: "fe80::1%eth0.100",
+		},
+		{
+			// IPv6 address with a zone identifier containing dots and a port.
+			text:   "{{ \"[fe80::1%eth0.100]:9090\" | stripDomain }}",
+			output: "[fe80::1%eth0.100]:9090",
+		},
+		{
+			// IPv4-mapped IPv6 address with a zone identifier containing dots.
+			text:   "{{ \"::ffff:192.0.2.1%eth0.100\" | stripDomain }}",
+			output: "::ffff:192.0.2.1%eth0.100",
+		},
 	})
 }