1 /* 2 * Copyright (C) 2018 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_DNSTLSSOCKET_H 18 #define _DNS_DNSTLSSOCKET_H 19 20 #include <openssl/ssl.h> 21 #include <future> 22 #include <mutex> 23 24 #include <android-base/thread_annotations.h> 25 #include <android-base/unique_fd.h> 26 #include <netdutils/Slice.h> 27 #include <netdutils/Status.h> 28 29 #include "DnsTlsServer.h" 30 #include "IDnsTlsSocket.h" 31 #include "LockedQueue.h" 32 33 namespace android { 34 namespace net { 35 36 class IDnsTlsSocketObserver; 37 class DnsTlsSessionCache; 38 39 // A class for managing a TLS socket that sends and receives messages in 40 // [length][value] format, with a 2-byte length (i.e. DNS-over-TCP format). 41 // This class is not aware of query-response pairing or anything else about DNS. 42 // For the observer: 43 // This class is not re-entrant: the observer is not permitted to wait for a call to query() 44 // or the destructor in a callback. Doing so will result in deadlocks. 45 // This class may call the observer at any time after initialize(), until the destructor 46 // returns (but not after). 47 class DnsTlsSocket : public IDnsTlsSocket { 48 public: DnsTlsSocket(const DnsTlsServer & server,unsigned mark,IDnsTlsSocketObserver * _Nonnull observer,DnsTlsSessionCache * _Nonnull cache)49 DnsTlsSocket(const DnsTlsServer& server, unsigned mark, 50 IDnsTlsSocketObserver* _Nonnull observer, DnsTlsSessionCache* _Nonnull cache) 51 : mMark(mark), mServer(server), mObserver(observer), mCache(cache) {} 52 ~DnsTlsSocket(); 53 54 // Creates the SSL context for this session and connect. Returns false on failure. 55 // This method should be called after construction and before use of a DnsTlsSocket. 56 // Only call this method once per DnsTlsSocket. 57 bool initialize() EXCLUDES(mLock); 58 59 // Send a query on the provided SSL socket. |query| contains 60 // the body of a query, not including the ID header. This function will typically return before 61 // the query is actually sent. If this function fails, DnsTlsSocketObserver will be 62 // notified that the socket is closed. 63 // Note that success here indicates successful sending, not receipt of a response. 64 // Thread-safe. 65 bool query(uint16_t id, const netdutils::Slice query) override EXCLUDES(mLock); 66 67 private: 68 // Lock to be held by the SSL event loop thread. This is not normally in contention. 69 std::mutex mLock; 70 71 // Forwards queries and receives responses. Blocks until the idle timeout. 72 void loop() EXCLUDES(mLock); 73 std::unique_ptr<std::thread> mLoopThread GUARDED_BY(mLock); 74 75 // On success, sets mSslFd to a socket connected to mAddr (the 76 // connection will likely be in progress if mProtocol is IPPROTO_TCP). 77 // On error, returns the errno. 78 netdutils::Status tcpConnect() REQUIRES(mLock); 79 80 // Connect an SSL session on the provided socket. If connection fails, closing the 81 // socket remains the caller's responsibility. 82 bssl::UniquePtr<SSL> sslConnect(int fd) REQUIRES(mLock); 83 84 // Disconnect the SSL session and close the socket. 85 void sslDisconnect() REQUIRES(mLock); 86 87 // Writes a buffer to the socket. 88 bool sslWrite(const netdutils::Slice buffer) REQUIRES(mLock); 89 90 // Reads exactly the specified number of bytes from the socket, or fails. 91 // Returns SSL_ERROR_NONE on success. 92 // If |wait| is true, then this function always blocks. Otherwise, it 93 // will return SSL_ERROR_WANT_READ if there is no data from the server to read. 94 int sslRead(const netdutils::Slice buffer, bool wait) REQUIRES(mLock); 95 96 bool sendQuery(const std::vector<uint8_t>& buf) REQUIRES(mLock); 97 bool readResponse() REQUIRES(mLock); 98 99 // Similar to query(), this function uses incrementEventFd to send a message to the 100 // loop thread. However, instead of incrementing the counter by one (indicating a 101 // new query), it wraps the counter to negative, which we use to indicate a shutdown 102 // request. 103 void requestLoopShutdown() EXCLUDES(mLock); 104 105 // This function sends a message to the loop thread by incrementing mEventFd. 106 bool incrementEventFd(int64_t count) EXCLUDES(mLock); 107 108 // Queue of pending queries. query() pushes items onto the queue and notifies 109 // the loop thread by incrementing mEventFd. loop() reads items off the queue. 110 LockedQueue<std::vector<uint8_t>> mQueue; 111 112 // eventfd socket used for notifying the SSL thread when queries are ready to send. 113 // This socket acts similarly to an atomic counter, incremented by query() and cleared 114 // by loop(). We have to use a socket because the SSL thread needs to wait in poll() 115 // for input from either a remote server or a query thread. Since eventfd does not have 116 // EOF, we indicate a close request by setting the counter to a negative number. 117 // This file descriptor is opened by initialize(), and closed implicitly after 118 // destruction. 119 base::unique_fd mEventFd; 120 121 // SSL Socket fields. 122 bssl::UniquePtr<SSL_CTX> mSslCtx GUARDED_BY(mLock); 123 base::unique_fd mSslFd GUARDED_BY(mLock); 124 bssl::UniquePtr<SSL> mSsl GUARDED_BY(mLock); 125 static constexpr std::chrono::seconds kIdleTimeout = std::chrono::seconds(20); 126 127 const unsigned mMark; // Socket mark 128 const DnsTlsServer mServer; 129 IDnsTlsSocketObserver* _Nonnull const mObserver; 130 DnsTlsSessionCache* _Nonnull const mCache; 131 }; 132 133 } // end of namespace net 134 } // end of namespace android 135 136 #endif // _DNS_DNSTLSSOCKET_H 137