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