ipc/ipc_channel_posix.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef IPC_IPC_CHANNEL_POSIX_H_
   6 #define IPC_IPC_CHANNEL_POSIX_H_
   7
   8 #include "ipc/ipc_channel.h"
   9
  10 #include <sys/socket.h>  // for CMSG macros
  11
  12 #include <queue>
  13 #include <set>
  14 #include <string>
  15 #include <vector>
  16
  17 #include "base/files/scoped_file.h"
  18 #include "base/message_loop/message_loop.h"
  19 #include "base/process/process.h"
  20 #include "ipc/ipc_channel_reader.h"
  21 #include "ipc/ipc_message_attachment_set.h"
  22
  23 namespace IPC {
  24
  25 class IPC_EXPORT ChannelPosix : public Channel,
  26                                 public internal::ChannelReader,
  27                                 public base::MessageLoopForIO::Watcher {
  28  public:
  29   // |broker| must outlive the newly created object.
  30   ChannelPosix(const IPC::ChannelHandle& channel_handle,
  31                Mode mode,
  32                Listener* listener,
  33                AttachmentBroker* broker);
  34   ~ChannelPosix() override;
  35
  36   // Channel implementation
  37   bool Connect() override;
  38   void Close() override;
  39   bool Send(Message* message) override;
  40   AttachmentBroker* GetAttachmentBroker() override;
  41   base::ProcessId GetPeerPID() const override;
  42   base::ProcessId GetSelfPID() const override;
  43   int GetClientFileDescriptor() const override;
  44   base::ScopedFD TakeClientFileDescriptor() override;
  45
  46   // Returns true if the channel supports listening for connections.
  47   bool AcceptsConnections() const;
  48
  49   // Returns true if the channel supports listening for connections and is
  50   // currently connected.
  51   bool HasAcceptedConnection() const;
  52
  53   // Closes any currently connected socket, and returns to a listening state
  54   // for more connections.
  55   void ResetToAcceptingConnectionState();
  56
  57   // Returns true if the peer process' effective user id can be determined, in
  58   // which case the supplied peer_euid is updated with it.
  59   bool GetPeerEuid(uid_t* peer_euid) const;
  60
  61   void CloseClientFileDescriptor();
  62
  63   static bool IsNamedServerInitialized(const std::string& channel_id);
  64 #if defined(OS_LINUX)
  65   static void SetGlobalPid(int pid);
  66 #endif  // OS_LINUX
  67
  68  private:
  69   bool CreatePipe(const IPC::ChannelHandle& channel_handle);
  70
  71   bool ProcessOutgoingMessages();
  72
  73   bool AcceptConnection();
  74   void ClosePipeOnError();
  75   int GetHelloMessageProcId() const;
  76   void QueueHelloMessage();
  77   void CloseFileDescriptors(Message* msg);
  78   void QueueCloseFDMessage(int fd, int hops);
  79
  80   // ChannelReader implementation.
  81   ReadState ReadData(char* buffer, int buffer_len, int* bytes_read) override;
  82   bool WillDispatchInputMessage(Message* msg) override;
  83   bool DidEmptyInputBuffers() override;
  84   void HandleInternalMessage(const Message& msg) override;
  85
  86   // Finds the set of file descriptors in the given message.  On success,
  87   // appends the descriptors to the input_fds_ member and returns true
  88   //
  89   // Returns false if the message was truncated. In this case, any handles that
  90   // were sent will be closed.
  91   bool ExtractFileDescriptorsFromMsghdr(msghdr* msg);
  92
  93   // Closes all handles in the input_fds_ list and clears the list. This is
  94   // used to clean up handles in error conditions to avoid leaking the handles.
  95   void ClearInputFDs();
  96
  97   // MessageLoopForIO::Watcher implementation.
  98   void OnFileCanReadWithoutBlocking(int fd) override;
  99   void OnFileCanWriteWithoutBlocking(int fd) override;
 100
 101   Mode mode_;
 102
 103   base::ProcessId peer_pid_;
 104
 105   // After accepting one client connection on our server socket we want to
 106   // stop listening.
 107   base::MessageLoopForIO::FileDescriptorWatcher
 108   server_listen_connection_watcher_;
 109   base::MessageLoopForIO::FileDescriptorWatcher read_watcher_;
 110   base::MessageLoopForIO::FileDescriptorWatcher write_watcher_;
 111
 112   // Indicates whether we're currently blocked waiting for a write to complete.
 113   bool is_blocked_on_write_;
 114   bool waiting_connect_;
 115
 116   // If sending a message blocks then we use this variable
 117   // to keep track of where we are.
 118   size_t message_send_bytes_written_;
 119
 120   // File descriptor we're listening on for new connections if we listen
 121   // for connections.
 122   base::ScopedFD server_listen_pipe_;
 123
 124   // The pipe used for communication.
 125   base::ScopedFD pipe_;
 126
 127   // For a server, the client end of our socketpair() -- the other end of our
 128   // pipe_ that is passed to the client.
 129   base::ScopedFD client_pipe_;
 130   mutable base::Lock client_pipe_lock_;  // Lock that protects |client_pipe_|.
 131
 132   // The "name" of our pipe.  On Windows this is the global identifier for
 133   // the pipe.  On POSIX it's used as a key in a local map of file descriptors.
 134   std::string pipe_name_;
 135
 136   // Messages to be sent are queued here.
 137   std::queue<Message*> output_queue_;
 138
 139   // We assume a worst case: kReadBufferSize bytes of messages, where each
 140   // message has no payload and a full complement of descriptors.
 141   static const size_t kMaxReadFDs =
 142       (Channel::kReadBufferSize / sizeof(IPC::Message::Header)) *
 143       MessageAttachmentSet::kMaxDescriptorsPerMessage;
 144
 145   // Buffer size for file descriptors used for recvmsg. On Mac the CMSG macros
 146   // are not constant so we have to pick a "large enough" padding for headers.
 147 #if defined(OS_MACOSX)
 148   static const size_t kMaxReadFDBuffer = 1024 + sizeof(int) * kMaxReadFDs;
 149 #else
 150   static const size_t kMaxReadFDBuffer = CMSG_SPACE(sizeof(int) * kMaxReadFDs);
 151 #endif
 152   static_assert(kMaxReadFDBuffer <= 8192,
 153                 "kMaxReadFDBuffer too big for a stack buffer");
 154
 155   // File descriptors extracted from messages coming off of the channel. The
 156   // handles may span messages and come off different channels from the message
 157   // data (in the case of READWRITE), and are processed in FIFO here.
 158   // NOTE: The implementation assumes underlying storage here is contiguous, so
 159   // don't change to something like std::deque<> without changing the
 160   // implementation!
 161   std::vector<int> input_fds_;
 162
 163
 164   void ResetSafely(base::ScopedFD* fd);
 165   bool in_dtor_;
 166
 167 #if defined(OS_MACOSX)
 168   // On OSX, sent FDs must not be closed until we get an ack.
 169   // Keep track of sent FDs here to make sure the remote is not
 170   // trying to bamboozle us.
 171   std::set<int> fds_to_close_;
 172 #endif
 173
 174   // True if we are responsible for unlinking the unix domain socket file.
 175   bool must_unlink_;
 176
 177 #if defined(OS_LINUX)
 178   // If non-zero, overrides the process ID sent in the hello message.
 179   static int global_pid_;
 180 #endif  // OS_LINUX
 181
 182   // |broker_| must outlive this instance.
 183   AttachmentBroker* broker_;
 184
 185   DISALLOW_IMPLICIT_CONSTRUCTORS(ChannelPosix);
 186 };
 187
 188 }  // namespace IPC
 189
 190 #endif  // IPC_IPC_CHANNEL_POSIX_H_