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_SECURE_SERVICE_VERSION_TXT_RECORD(ver) ("v=" #ver)
30
31 const char* kADBSecurePairingServiceTxtRecord =
32 ADB_SECURE_SERVICE_VERSION_TXT_RECORD(ADB_SECURE_SERVICE_VERSION);
33 const char* kADBSecureConnectServiceTxtRecord =
34 ADB_SECURE_SERVICE_VERSION_TXT_RECORD(ADB_SECURE_SERVICE_VERSION);
35
36 #define ADB_FULL_MDNS_SERVICE_TYPE(atype) ("_" atype "._tcp")
37 const char* kADBDNSServices[] = {ADB_FULL_MDNS_SERVICE_TYPE(ADB_MDNS_SERVICE_TYPE),
38 ADB_FULL_MDNS_SERVICE_TYPE(ADB_MDNS_TLS_PAIRING_TYPE),
39 ADB_FULL_MDNS_SERVICE_TYPE(ADB_MDNS_TLS_CONNECT_TYPE)};
40
41 const char* kADBDNSServiceTxtRecords[] = {
42 nullptr,
43 kADBSecurePairingServiceTxtRecord,
44 kADBSecureConnectServiceTxtRecord,
45 };
46
47 #if ADB_HOST
48 namespace {
49
50 std::atomic<bool> g_allowedlist_configured{false};
51 [[clang::no_destroy]] std::set<int> g_autoconn_allowedlist;
52
config_auto_connect_services()53 void config_auto_connect_services() {
54 bool expected = false;
55 if (!g_allowedlist_configured.compare_exchange_strong(expected, true)) {
56 return;
57 }
58
59 // ADB_MDNS_AUTO_CONNECT is a comma-delimited list of mdns services
60 // that are allowed to auto-connect. By default, only allow "adb-tls-connect"
61 // to auto-connect, since this is filtered down to auto-connect only to paired
62 // devices.
63 g_autoconn_allowedlist.insert(kADBSecureConnectServiceRefIndex);
64 const char* srvs = getenv("ADB_MDNS_AUTO_CONNECT");
65 if (!srvs) {
66 return;
67 }
68
69 if (strcmp(srvs, "0") == 0) {
70 D("Disabling all auto-connecting");
71 g_autoconn_allowedlist.clear();
72 return;
73 }
74
75 if (strcmp(srvs, "all") == 0) {
76 D("Allow all auto-connecting");
77 g_autoconn_allowedlist.insert(kADBTransportServiceRefIndex);
78 return;
79 }
80
81 // Selectively choose which services to allow auto-connect.
82 // E.g. ADB_MDNS_AUTO_CONNECT=adb,adb-tls-connect would allow
83 // _adb._tcp and _adb-tls-connnect._tcp services to auto-connect.
84 auto srvs_list = android::base::Split(srvs, ",");
85 std::set<int> new_allowedlist;
86 for (const auto& item : srvs_list) {
87 auto full_srv = android::base::StringPrintf("_%s._tcp", item.data());
88 std::optional<int> idx = adb_DNSServiceIndexByName(full_srv);
89 if (idx.has_value()) {
90 new_allowedlist.insert(*idx);
91 }
92 }
93
94 if (!new_allowedlist.empty()) {
95 g_autoconn_allowedlist = std::move(new_allowedlist);
96 }
97
98 std::string res;
99 std::for_each(g_autoconn_allowedlist.begin(), g_autoconn_allowedlist.end(), [&](const int& i) {
100 res += kADBDNSServices[i];
101 res += ",";
102 });
103 D("mdns auto-connect allowedlist: [%s]", res.data());
104 }
105
106 } // namespace
107
adb_DNSServiceIndexByName(std::string_view reg_type)108 std::optional<int> adb_DNSServiceIndexByName(std::string_view reg_type) {
109 for (int i = 0; i < kNumADBDNSServices; ++i) {
110 if (!strncmp(reg_type.data(), kADBDNSServices[i], strlen(kADBDNSServices[i]))) {
111 return i;
112 }
113 }
114 return std::nullopt;
115 }
116
adb_DNSServiceShouldAutoConnect(std::string_view reg_type,std::string_view service_name)117 bool adb_DNSServiceShouldAutoConnect(std::string_view reg_type, std::string_view service_name) {
118 config_auto_connect_services();
119
120 // Try to auto-connect to any "_adb" or "_adb-tls-connect" services excluding emulator services.
121 std::optional<int> index = adb_DNSServiceIndexByName(reg_type);
122 if (!index ||
123 (index != kADBTransportServiceRefIndex && index != kADBSecureConnectServiceRefIndex)) {
124 return false;
125 }
126 if (g_autoconn_allowedlist.find(*index) == g_autoconn_allowedlist.end()) {
127 D("Auto-connect for reg_type '%s' disabled", reg_type.data());
128 return false;
129 }
130 // Ignore adb-EMULATOR* service names, as it interferes with the
131 // emulator ports that are already connected.
132 if (android::base::StartsWith(service_name, "adb-EMULATOR")) {
133 LOG(INFO) << "Ignoring emulator transport service [" << service_name << "]";
134 return false;
135 }
136 return true;
137 }
138
139 #endif // ADB_HOST
140