preserve ipv6 brackets and zone when stripping default ports

transport/url.go

@@ -30,13 +30,12 @@ func NormalizeURL(input string) (string, error) {
 	// lowercase host
 	parsed.Host = strings.ToLower(parsed.Host)
 
-	host := parsed.Hostname()
 	port := parsed.Port()
 
-	// strip default ports
+	// strip default ports by suffix-trim so ipv6 brackets and zone survive
 	if (parsed.Scheme == "wss" && port == "443") ||
 		(parsed.Scheme == "ws" && port == "80") {
-		parsed.Host = host
+		parsed.Host = strings.TrimSuffix(parsed.Host, ":"+port)
 	}
 
 	parsed.Path = strings.TrimRight(parsed.Path, "/")

transport/url_test.go

@@ -132,6 +132,21 @@ func TestNormalizeURL(t *testing.T) {
 			input:    "ws://relay.example.com:80",
 			expected: "ws://relay.example.com",
 		},
+		{
+			name:     "strip default wss port preserves ipv6 brackets",
+			input:    "wss://[::1]:443",
+			expected: "wss://[::1]",
+		},
+		{
+			name:     "strip default ws port preserves ipv6 brackets",
+			input:    "ws://[::1]:80",
+			expected: "ws://[::1]",
+		},
+		{
+			name:     "strip default port preserves ipv6 zone",
+			input:    "wss://[fe80::1%25eth0]:443/",
+			expected: "wss://[fe80::1%25eth0]",
+		},
 		{
 			name:     "preserve non-default port",
 			input:    "wss://relay.example.com:8080",
@@ -174,6 +189,24 @@ func TestNormalizeURL(t *testing.T) {
 	}
 }
 
+func TestNormalizeURLIdempotent(t *testing.T) {
+	inputs := []string{
+		"wss://[::1]:443",
+		"ws://[::1]:80",
+		"wss://[fe80::1%25eth0]:443/",
+		"wss://relay.example.com:443/",
+		"wss://relay.example.com:8080/path",
+	}
+
+	for _, input := range inputs {
+		once, err := NormalizeURL(input)
+		assert.NoError(t, err)
+		twice, err := NormalizeURL(once)
+		assert.NoError(t, err)
+		assert.Equal(t, once, twice, "normalizing %q twice must be stable", input)
+	}
+}
+
 func TestNormalizeURLError(t *testing.T) {
 	_, err := NormalizeURL("http://relay.example.com")
 	assert.ErrorIs(t, err, InvalidProtocol)