1 /*
2 * Copyright (C) 2020 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include "client/mdns_utils.h"
18
19 #include <android-base/strings.h>
20
21 namespace mdns {
22
23 // <Instance>.<Service>.<Domain>
mdns_parse_instance_name(std::string_view name)24 std::optional<MdnsInstance> mdns_parse_instance_name(std::string_view name) {
25 CHECK(!name.empty());
26
27 // Return the whole name if it doesn't fall under <Instance>.<Service>.<Domain> or
28 // <Instance>.<Service>
29 bool has_local_suffix = false;
30 // Strip the local suffix, if any
31 {
32 std::string local_suffix = ".local";
33 local_suffix += android::base::EndsWith(name, ".") ? "." : "";
34
35 if (android::base::ConsumeSuffix(&name, local_suffix)) {
36 if (name.empty()) {
37 return std::nullopt;
38 }
39 has_local_suffix = true;
40 }
41 }
42
43 std::string transport;
44 // Strip the transport suffix, if any
45 {
46 std::string add_dot = (!has_local_suffix && android::base::EndsWith(name, ".")) ? "." : "";
47 std::array<std::string, 2> transport_suffixes{"._tcp", "._udp"};
48
49 for (const auto& t : transport_suffixes) {
50 if (android::base::ConsumeSuffix(&name, t + add_dot)) {
51 if (name.empty()) {
52 return std::nullopt;
53 }
54 transport = t.substr(1);
55 break;
56 }
57 }
58
59 if (has_local_suffix && transport.empty()) {
60 return std::nullopt;
61 }
62 }
63
64 if (!has_local_suffix && transport.empty()) {
65 return std::make_optional<MdnsInstance>(name, "", "");
66 }
67
68 // Split the service name from the instance name
69 auto pos = name.rfind(".");
70 if (pos == 0 || pos == std::string::npos || pos == name.size() - 1) {
71 return std::nullopt;
72 }
73
74 return std::make_optional<MdnsInstance>(name.substr(0, pos), name.substr(pos + 1), transport);
75 }
76
77 } // namespace mdns
78