blob: 1439ea90e2c4da1a333c7f912d147584b9239462 [file] [log] [blame]
* Copyright (C) 2018 The Android Open Source Project
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#include <openssl/ssl.h>
#include <future>
#include <mutex>
#include <android-base/thread_annotations.h>
#include <android-base/unique_fd.h>
#include <netdutils/Slice.h>
#include <netdutils/Status.h>
#include "DnsTlsServer.h"
#include "IDnsTlsSocket.h"
#include "LockedQueue.h"
namespace android {
namespace net {
class IDnsTlsSocketObserver;
class DnsTlsSessionCache;
// A class for managing a TLS socket that sends and receives messages in
// [length][value] format, with a 2-byte length (i.e. DNS-over-TCP format).
// This class is not aware of query-response pairing or anything else about DNS.
// For the observer:
// This class is not re-entrant: the observer is not permitted to wait for a call to query()
// or the destructor in a callback. Doing so will result in deadlocks.
// This class may call the observer at any time after initialize(), until the destructor
// returns (but not after).
class DnsTlsSocket : public IDnsTlsSocket {
DnsTlsSocket(const DnsTlsServer& server, unsigned mark,
IDnsTlsSocketObserver* _Nonnull observer, DnsTlsSessionCache* _Nonnull cache)
: mMark(mark), mServer(server), mObserver(observer), mCache(cache) {}
// Creates the SSL context for this session and connect. Returns false on failure.
// This method should be called after construction and before use of a DnsTlsSocket.
// Only call this method once per DnsTlsSocket.
bool initialize() EXCLUDES(mLock);
// Send a query on the provided SSL socket. |query| contains
// the body of a query, not including the ID header. This function will typically return before
// the query is actually sent. If this function fails, DnsTlsSocketObserver will be
// notified that the socket is closed.
// Note that success here indicates successful sending, not receipt of a response.
// Thread-safe.
bool query(uint16_t id, const netdutils::Slice query) override EXCLUDES(mLock);
// Lock to be held by the SSL event loop thread. This is not normally in contention.
std::mutex mLock;
// Forwards queries and receives responses. Blocks until the idle timeout.
void loop() EXCLUDES(mLock);
std::unique_ptr<std::thread> mLoopThread GUARDED_BY(mLock);
// On success, sets mSslFd to a socket connected to mAddr (the
// connection will likely be in progress if mProtocol is IPPROTO_TCP).
// On error, returns the errno.
netdutils::Status tcpConnect() REQUIRES(mLock);
// Connect an SSL session on the provided socket. If connection fails, closing the
// socket remains the caller's responsibility.
bssl::UniquePtr<SSL> sslConnect(int fd) REQUIRES(mLock);
// Disconnect the SSL session and close the socket.
void sslDisconnect() REQUIRES(mLock);
// Writes a buffer to the socket.
bool sslWrite(const netdutils::Slice buffer) REQUIRES(mLock);
// Reads exactly the specified number of bytes from the socket, or fails.
// Returns SSL_ERROR_NONE on success.
// If |wait| is true, then this function always blocks. Otherwise, it
// will return SSL_ERROR_WANT_READ if there is no data from the server to read.
int sslRead(const netdutils::Slice buffer, bool wait) REQUIRES(mLock);
bool sendQuery(const std::vector<uint8_t>& buf) REQUIRES(mLock);
bool readResponse() REQUIRES(mLock);
// It is only used for DNS-OVER-TLS internal test.
bool setTestCaCertificate() REQUIRES(mLock);
// Similar to query(), this function uses incrementEventFd to send a message to the
// loop thread. However, instead of incrementing the counter by one (indicating a
// new query), it wraps the counter to negative, which we use to indicate a shutdown
// request.
void requestLoopShutdown() EXCLUDES(mLock);
// This function sends a message to the loop thread by incrementing mEventFd.
bool incrementEventFd(int64_t count) EXCLUDES(mLock);
// Queue of pending queries. query() pushes items onto the queue and notifies
// the loop thread by incrementing mEventFd. loop() reads items off the queue.
LockedQueue<std::vector<uint8_t>> mQueue;
// eventfd socket used for notifying the SSL thread when queries are ready to send.
// This socket acts similarly to an atomic counter, incremented by query() and cleared
// by loop(). We have to use a socket because the SSL thread needs to wait in poll()
// for input from either a remote server or a query thread. Since eventfd does not have
// EOF, we indicate a close request by setting the counter to a negative number.
// This file descriptor is opened by initialize(), and closed implicitly after
// destruction.
base::unique_fd mEventFd;
// SSL Socket fields.
bssl::UniquePtr<SSL_CTX> mSslCtx GUARDED_BY(mLock);
base::unique_fd mSslFd GUARDED_BY(mLock);
bssl::UniquePtr<SSL> mSsl GUARDED_BY(mLock);
static constexpr std::chrono::seconds kIdleTimeout = std::chrono::seconds(20);
const unsigned mMark; // Socket mark
const DnsTlsServer mServer;
IDnsTlsSocketObserver* _Nonnull const mObserver;
DnsTlsSessionCache* _Nonnull const mCache;
} // end of namespace net
} // end of namespace android