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