1 /*
2  * Copyright (C) 2017 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 
18 #ifndef DNS_TLS_FRONTEND_H
19 #define DNS_TLS_FRONTEND_H
20 
21 #include <arpa/nameser.h>
22 
23 #include <atomic>
24 #include <mutex>
25 #include <string>
26 #include <thread>
27 #include <unordered_map>
28 #include <vector>
29 
30 #include <android-base/thread_annotations.h>
31 #include <android-base/unique_fd.h>
32 #include <openssl/ssl.h>
33 
34 namespace test {
35 
36 /*
37  * Simple DNS over TLS reverse proxy that forwards to a UDP backend.
38  * Only handles a single request at a time.
39  */
40 class DnsTlsFrontend {
41   public:
42     DnsTlsFrontend(const std::string& listen_address = kDefaultListenAddr,
43                    const std::string& listen_service = kDefaultListenService,
44                    const std::string& backend_address = kDefaultBackendAddr,
45                    const std::string& backend_service = kDefaultBackendService)
listen_address_(listen_address)46         : listen_address_(listen_address),
47           listen_service_(listen_service),
48           backend_address_(backend_address),
49           backend_service_(backend_service) {}
~DnsTlsFrontend()50     ~DnsTlsFrontend() { stopServer(); }
listen_address()51     const std::string& listen_address() const { return listen_address_; }
listen_service()52     const std::string& listen_service() const { return listen_service_; }
running()53     bool running() const { return socket_ != -1; }
54     bool startServer();
55     bool stopServer();
56 
queries()57     int queries() const { return queries_; }
clearQueries()58     void clearQueries() { queries_ = 0; }
59     bool waitForQueries(int expected_count) const;
acceptConnectionsCount()60     int acceptConnectionsCount() const { return accept_connection_count_; }
61 
set_chain_length(int length)62     void set_chain_length(int length) { chain_length_ = length; }
setHangOnHandshakeForTesting(bool hangOnHandshake)63     void setHangOnHandshakeForTesting(bool hangOnHandshake) { hangOnHandshake_ = hangOnHandshake; }
64 
65     static constexpr char kDefaultListenAddr[] = "127.0.0.3";
66     static constexpr char kDefaultListenService[] = "853";
67     static constexpr char kDefaultBackendAddr[] = "127.0.0.3";
68     static constexpr char kDefaultBackendService[] = "53";
69 
70   private:
71     void requestHandler();
72     int handleRequests(SSL* ssl, int clientFd);
73 
74     // Trigger the handler thread to terminate.
75     bool sendToEventFd();
76 
77     // Used in the handler thread for the termination signal.
78     void handleEventFd();
79 
80     std::string listen_address_;
81     std::string listen_service_;
82     std::string backend_address_;
83     std::string backend_service_;
84     bssl::UniquePtr<SSL_CTX> ctx_;
85     // Socket on which the server is listening for a TCP connection with a client.
86     android::base::unique_fd socket_;
87     // Socket used to communicate with the backend DNS server.
88     android::base::unique_fd backend_socket_;
89     // Eventfd used to signal for the handler thread termination.
90     android::base::unique_fd event_fd_;
91     std::atomic<int> queries_ = 0;
92     std::atomic<int> accept_connection_count_ = 0;
93     std::thread handler_thread_ GUARDED_BY(update_mutex_);
94     std::mutex update_mutex_;
95     int chain_length_ = 1;
96     std::atomic<bool> hangOnHandshake_ = false;
97 };
98 
99 }  // namespace test
100 
101 #endif  // DNS_TLS_FRONTEND_H
102