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 #ifndef _DNS_DNSTLSTRANSPORT_H
18 #define _DNS_DNSTLSTRANSPORT_H
19 
20 #include <future>
21 #include <map>
22 #include <mutex>
23 #include <vector>
24 
25 #include <android-base/thread_annotations.h>
26 #include <android-base/unique_fd.h>
27 #include <netdutils/Slice.h>
28 
29 #include "DnsTlsQueryMap.h"
30 #include "DnsTlsServer.h"
31 #include "DnsTlsSessionCache.h"
32 #include "IDnsTlsSocket.h"
33 #include "IDnsTlsSocketObserver.h"
34 
35 namespace android {
36 namespace net {
37 
38 class IDnsTlsSocketFactory;
39 
40 // Manages at most one DnsTlsSocket at a time.  This class handles socket lifetime issues,
41 // such as reopening the socket and reissuing pending queries.
42 class DnsTlsTransport : public IDnsTlsSocketObserver {
43   public:
DnsTlsTransport(const DnsTlsServer & server,unsigned mark,IDnsTlsSocketFactory * _Nonnull factory)44     DnsTlsTransport(const DnsTlsServer& server, unsigned mark,
45                     IDnsTlsSocketFactory* _Nonnull factory)
46         : mMark(mark), mServer(server), mFactory(factory) {}
47     ~DnsTlsTransport();
48 
49     using Response = DnsTlsQueryMap::Response;
50     using Result = DnsTlsQueryMap::Result;
51 
52     // Given a |query|, this method sends it to the server and returns the result asynchronously.
53     std::future<Result> query(const netdutils::Slice query) EXCLUDES(mLock);
54 
55     // Check that a given TLS server is fully working on the specified netid.
56     // This function is used in ResolverController to ensure that we don't enable DNS over TLS
57     // on networks where it doesn't actually work.
58     static bool validate(const DnsTlsServer& server, unsigned netid, uint32_t mark);
59 
60     int getConnectCounter() const EXCLUDES(mLock);
61 
62     // Implement IDnsTlsSocketObserver
63     void onResponse(std::vector<uint8_t> response) override;
64     void onClosed() override EXCLUDES(mLock);
65 
66   private:
67     mutable std::mutex mLock;
68 
69     DnsTlsSessionCache mCache;
70     DnsTlsQueryMap mQueries;
71 
72     const unsigned mMark;  // Socket mark
73     const DnsTlsServer mServer;
74     IDnsTlsSocketFactory* _Nonnull const mFactory;
75 
76     void doConnect() REQUIRES(mLock);
77 
78     // doReconnect is used by onClosed.  It runs on the reconnect thread.
79     void doReconnect() EXCLUDES(mLock);
80     std::unique_ptr<std::thread> mReconnectThread GUARDED_BY(mLock);
81 
82     // Used to prevent onClosed from starting a reconnect during the destructor.
83     bool mClosing GUARDED_BY(mLock) = false;
84 
85     // Sending queries on the socket is thread-safe, but construction/destruction is not.
86     std::unique_ptr<IDnsTlsSocket> mSocket GUARDED_BY(mLock);
87 
88     // Send a query to the socket.
89     bool sendQuery(const DnsTlsQueryMap::Query& q) REQUIRES(mLock);
90 
91     // The number of times an attempt to connect the nameserver.
92     int mConnectCounter GUARDED_BY(mLock) = 0;
93 };
94 
95 }  // end of namespace net
96 }  // end of namespace android
97 
98 #endif  // _DNS_DNSTLSTRANSPORT_H
99