1 /*
2 * Copyright (C) 2020 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 #define TRACE_TAG TRANSPORT
18
19 #include "adb_mdns.h"
20
21 #include <algorithm>
22 #include <set>
23
24 #include <android-base/stringprintf.h>
25 #include <android-base/strings.h>
26
27 #include "adb_trace.h"
28
29 #define ADB_FULL_MDNS_SERVICE_TYPE(atype) ("_" atype "._tcp")
30 const char* kADBDNSServices[] = {ADB_FULL_MDNS_SERVICE_TYPE(ADB_MDNS_SERVICE_TYPE),
31 ADB_FULL_MDNS_SERVICE_TYPE(ADB_MDNS_TLS_PAIRING_TYPE),
32 ADB_FULL_MDNS_SERVICE_TYPE(ADB_MDNS_TLS_CONNECT_TYPE)};
33
34 #if ADB_HOST
35 namespace {
36
37 std::atomic<bool> g_allowedlist_configured{false};
38 [[clang::no_destroy]] std::set<int> g_autoconn_allowedlist;
39
config_auto_connect_services()40 void config_auto_connect_services() {
41 bool expected = false;
42 if (!g_allowedlist_configured.compare_exchange_strong(expected, true)) {
43 return;
44 }
45
46 // ADB_MDNS_AUTO_CONNECT is a comma-delimited list of mdns services
47 // that are allowed to auto-connect. By default, only allow "adb-tls-connect"
48 // to auto-connect, since this is filtered down to auto-connect only to paired
49 // devices.
50 g_autoconn_allowedlist.insert(kADBSecureConnectServiceRefIndex);
51 const char* srvs = getenv("ADB_MDNS_AUTO_CONNECT");
52 if (!srvs) {
53 return;
54 }
55
56 if (strcmp(srvs, "0") == 0) {
57 D("Disabling all auto-connecting");
58 g_autoconn_allowedlist.clear();
59 return;
60 }
61
62 if (strcmp(srvs, "all") == 0) {
63 D("Allow all auto-connecting");
64 g_autoconn_allowedlist.insert(kADBTransportServiceRefIndex);
65 return;
66 }
67
68 // Selectively choose which services to allow auto-connect.
69 // E.g. ADB_MDNS_AUTO_CONNECT=adb,adb-tls-connect would allow
70 // _adb._tcp and _adb-tls-connnect._tcp services to auto-connect.
71 auto srvs_list = android::base::Split(srvs, ",");
72 std::set<int> new_allowedlist;
73 for (const auto& item : srvs_list) {
74 auto full_srv = android::base::StringPrintf("_%s._tcp", item.data());
75 std::optional<int> idx = adb_DNSServiceIndexByName(full_srv);
76 if (idx.has_value()) {
77 new_allowedlist.insert(*idx);
78 }
79 }
80
81 if (!new_allowedlist.empty()) {
82 g_autoconn_allowedlist = std::move(new_allowedlist);
83 }
84
85 std::string res;
86 std::for_each(g_autoconn_allowedlist.begin(), g_autoconn_allowedlist.end(), [&](const int& i) {
87 res += kADBDNSServices[i];
88 res += ",";
89 });
90 D("mdns auto-connect allowedlist: [%s]", res.data());
91 }
92
93 } // namespace
94
adb_DNSServiceIndexByName(std::string_view reg_type)95 std::optional<int> adb_DNSServiceIndexByName(std::string_view reg_type) {
96 for (int i = 0; i < kNumADBDNSServices; ++i) {
97 if (!strncmp(reg_type.data(), kADBDNSServices[i], strlen(kADBDNSServices[i]))) {
98 return i;
99 }
100 }
101 return std::nullopt;
102 }
103
adb_DNSServiceShouldAutoConnect(std::string_view reg_type,std::string_view service_name)104 bool adb_DNSServiceShouldAutoConnect(std::string_view reg_type, std::string_view service_name) {
105 config_auto_connect_services();
106
107 // Try to auto-connect to any "_adb" or "_adb-tls-connect" services excluding emulator services.
108 std::optional<int> index = adb_DNSServiceIndexByName(reg_type);
109 if (!index ||
110 (index != kADBTransportServiceRefIndex && index != kADBSecureConnectServiceRefIndex)) {
111 return false;
112 }
113 if (!g_autoconn_allowedlist.contains(*index)) {
114 D("Auto-connect for reg_type '%s' disabled", reg_type.data());
115 return false;
116 }
117 // Ignore adb-EMULATOR* service names, as it interferes with the
118 // emulator ports that are already connected.
119 if (android::base::StartsWith(service_name, "adb-EMULATOR")) {
120 LOG(INFO) << "Ignoring emulator transport service [" << service_name << "]";
121 return false;
122 }
123 return true;
124 }
125
126 #endif // ADB_HOST
127