helper: add ipaddr pkg to check for any IP addresses.

helper/ipaddr/ipaddr.go

@@ -0,0 +1,10 @@
+package ipaddr
+
+// IsAny checks if the given IP address is an IPv4 or IPv6 ANY address.
+func IsAny(ip string) bool {
+	return isAnyV4(ip) || isAnyV6(ip)
+}
+
+func isAnyV4(ip string) bool { return ip == "0.0.0.0" }
+
+func isAnyV6(ip string) bool { return ip == "::" || ip == "[::]" }

helper/ipaddr/ipaddr_test.go

@@ -0,0 +1,53 @@
+package ipaddr
+
+import (
+	"net"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func Test_IsAny(t *testing.T) {
+	testCases := []struct {
+		inputIP        string
+		expectedOutput bool
+		name           string
+	}{
+		{
+			inputIP:        "0.0.0.0",
+			expectedOutput: true,
+			name:           "string ipv4 any IP",
+		},
+		{
+			inputIP:        "::",
+			expectedOutput: true,
+			name:           "string ipv6 any IP",
+		},
+		{
+			inputIP:        net.IPv4zero.String(),
+			expectedOutput: true,
+			name:           "net.IP ipv4 any",
+		},
+		{
+			inputIP:        net.IPv6zero.String(),
+			expectedOutput: true,
+			name:           "net.IP ipv6 any",
+		},
+		{
+			inputIP:        "10.10.10.10",
+			expectedOutput: false,
+			name:           "internal ipv4 address",
+		},
+		{
+			inputIP:        "8.8.8.8",
+			expectedOutput: false,
+			name:           "public ipv4 address",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			require.Equal(t, tc.expectedOutput, IsAny(tc.inputIP))
+		})
+	}
+}