dbus: implement dbus_parse_address

This parses D-Bus addresses according to spec. It does significantly fewer copies than dbus_parse_address.

Signed-off-by: Ophestra <cat@gensokyo.uk>

dbus/address_escape_test.go

@@ -0,0 +1,55 @@
+package dbus
+
+import (
+	"testing"
+)
+
+func TestUnescapeValue(t *testing.T) {
+	testCases := []struct {
+		value   string
+		want    string
+		wantErr ParseError
+	}{
+		// upstream test cases
+		{value: "abcde", want: "abcde"},
+		{value: "", want: ""},
+		{value: "%20%20", want: "  "},
+		{value: "%24", want: "$"},
+		{value: "%25", want: "%"},
+		{value: "abc%24", want: "abc$"},
+		{value: "%24abc", want: "$abc"},
+		{value: "abc%24abc", want: "abc$abc"},
+		{value: "/", want: "/"},
+		{value: "-", want: "-"},
+		{value: "_", want: "_"},
+		{value: "A", want: "A"},
+		{value: "I", want: "I"},
+		{value: "Z", want: "Z"},
+		{value: "a", want: "a"},
+		{value: "i", want: "i"},
+		{value: "z", want: "z"},
+		/* Bug: https://bugs.freedesktop.org/show_bug.cgi?id=53499 */
+		{value: "%c3%b6", want: "\xc3\xb6"},
+
+		{value: "%a", wantErr: ErrBadValHexLength},
+		{value: "%q", wantErr: ErrBadValHexLength},
+		{value: "%az", wantErr: ErrBadValHexByte},
+		{value: "%%", wantErr: ErrBadValLength},
+		{value: "%$$", wantErr: ErrBadValHexByte},
+		{value: "abc%a", wantErr: ErrBadValHexLength},
+		{value: "%axyz", wantErr: ErrBadValHexByte},
+		{value: "%", wantErr: ErrBadValLength},
+		{value: "$", wantErr: ErrBadValByte},
+		{value: " ", wantErr: ErrBadValByte},
+	}
+
+	for _, tc := range testCases {
+		t.Run("unescape "+tc.value, func(t *testing.T) {
+			if got, errno := unescapeValue([]byte(tc.value)); errno != tc.wantErr {
+				t.Errorf("unescapeValue() errno = %v, wantErr %v", errno, tc.wantErr)
+			} else if tc.wantErr == errSuccess && string(got) != tc.want {
+				t.Errorf("unescapeValue() = %q, want %q", got, tc.want)
+			}
+		})
+	}
+}