1 // Copyright (c) 2011 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.
5 #ifndef IPC_IPC_CHANNEL_H_
6 #define IPC_IPC_CHANNEL_H_
9 #include "base/compiler_specific.h"
10 #include "ipc/ipc_channel_handle.h"
11 #include "ipc/ipc_message.h"
15 //------------------------------------------------------------------------------
17 // http://www.chromium.org/developers/design-documents/inter-process-communication
18 // for overview of IPC in Chromium.
20 // Channels are implemented using named pipes on Windows, and
21 // socket pairs (or in some special cases unix domain sockets) on POSIX.
22 // On Windows we access pipes in various processes by name.
23 // On POSIX we pass file descriptors to child processes and assign names to them
25 // In general on POSIX we do not use unix domain sockets due to security
26 // concerns and the fact that they can leave garbage around the file system
27 // (MacOS does not support abstract named unix domain sockets).
28 // You can use unix domain sockets if you like on POSIX by constructing the
29 // the channel with the mode set to one of the NAMED modes. NAMED modes are
30 // currently used by automation and service processes.
32 class IPC_EXPORT Channel
: public Message::Sender
{
33 // Security tests need access to the pipe handle.
34 friend class ChannelTest
;
37 // Implemented by consumers of a Channel to receive messages.
38 class IPC_EXPORT Listener
{
40 virtual ~Listener() {}
42 // Called when a message is received. Returns true iff the message was
44 virtual bool OnMessageReceived(const Message
& message
) = 0;
46 // Called when the channel is connected and we have received the internal
47 // Hello message from the peer.
48 virtual void OnChannelConnected(int32 peer_pid
) {}
50 // Called when an error is detected that causes the channel to close.
51 // This method is not called when a channel is closed normally.
52 virtual void OnChannelError() {}
55 // Called on the server side when a channel that listens for connections
56 // denies an attempt to connect.
57 virtual void OnChannelDenied() {}
59 // Called on the server side when a channel that listens for connections
60 // has an error that causes the listening channel to close.
61 virtual void OnChannelListenError() {}
65 // Flags to test modes
68 MODE_SERVER_FLAG
= 0x1,
69 MODE_CLIENT_FLAG
= 0x2,
70 MODE_NAMED_FLAG
= 0x4,
72 MODE_OPEN_ACCESS_FLAG
= 0x8, // Don't restrict access based on client UID.
76 // Some Standard Modes
78 MODE_NONE
= MODE_NO_FLAG
,
79 MODE_SERVER
= MODE_SERVER_FLAG
,
80 MODE_CLIENT
= MODE_CLIENT_FLAG
,
81 // Channels on Windows are named by default and accessible from other
82 // processes. On POSIX channels are anonymous by default and not accessible
83 // from other processes. Named channels work via named unix domain sockets.
84 // On Windows MODE_NAMED_SERVER is equivalent to MODE_SERVER and
85 // MODE_NAMED_CLIENT is equivalent to MODE_CLIENT.
86 MODE_NAMED_SERVER
= MODE_SERVER_FLAG
| MODE_NAMED_FLAG
,
87 MODE_NAMED_CLIENT
= MODE_CLIENT_FLAG
| MODE_NAMED_FLAG
,
89 // An "open" named server accepts connections from ANY client.
90 // The caller must then implement their own access-control based on the
91 // client process' user Id.
92 MODE_OPEN_NAMED_SERVER
= MODE_OPEN_ACCESS_FLAG
| MODE_SERVER_FLAG
|
97 // The maximum message size in bytes. Attempting to receive a message of this
98 // size or bigger results in a channel error.
99 static const size_t kMaximumMessageSize
= 128 * 1024 * 1024;
101 // Ammount of data to read at once from the pipe.
102 static const size_t kReadBufferSize
= 4 * 1024;
104 // Initialize a Channel.
106 // |channel_handle| identifies the communication Channel. For POSIX, if
107 // the file descriptor in the channel handle is != -1, the channel takes
108 // ownership of the file descriptor and will close it appropriately, otherwise
109 // it will create a new descriptor internally.
110 // |mode| specifies whether this Channel is to operate in server mode or
111 // client mode. In server mode, the Channel is responsible for setting up the
112 // IPC object, whereas in client mode, the Channel merely connects to the
113 // already established IPC object.
114 // |listener| receives a callback on the current thread for each newly
117 Channel(const IPC::ChannelHandle
&channel_handle
, Mode mode
,
122 // Connect the pipe. On the server side, this will initiate
123 // waiting for connections. On the client, it attempts to
124 // connect to a pre-existing pipe. Note, calling Connect()
125 // will not block the calling thread and may complete
127 bool Connect() WARN_UNUSED_RESULT
;
129 // Close this Channel explicitly. May be called multiple times.
130 // On POSIX calling close on an IPC channel that listens for connections will
131 // cause it to close any accepted connections, and it will stop listening for
132 // new connections. If you just want to close the currently accepted
133 // connection and listen for new ones, use ResetToAcceptingConnectionState.
136 // Modify the Channel's listener.
137 void set_listener(Listener
* listener
);
139 // Send a message over the Channel to the listener on the other end.
141 // |message| must be allocated using operator new. This object will be
142 // deleted once the contents of the Message have been sent.
143 virtual bool Send(Message
* message
) OVERRIDE
;
145 #if defined(OS_POSIX) && !defined(OS_NACL)
146 // On POSIX an IPC::Channel wraps a socketpair(), this method returns the
147 // FD # for the client end of the socket.
148 // This method may only be called on the server side of a channel.
149 // This method can be called on any thread.
150 int GetClientFileDescriptor() const;
152 // Same as GetClientFileDescriptor, but transfers the ownership of the
153 // file descriptor to the caller.
154 // This method can be called on any thread.
155 int TakeClientFileDescriptor();
157 // On POSIX an IPC::Channel can either wrap an established socket, or it
158 // can wrap a socket that is listening for connections. Currently an
159 // IPC::Channel that listens for connections can only accept one connection
162 // Returns true if the channel supports listening for connections.
163 bool AcceptsConnections() const;
165 // Returns true if the channel supports listening for connections and is
166 // currently connected.
167 bool HasAcceptedConnection() const;
169 // Returns true if the peer process' effective user id can be determined, in
170 // which case the supplied client_euid is updated with it.
171 bool GetClientEuid(uid_t
* client_euid
) const;
173 // Closes any currently connected socket, and returns to a listening state
174 // for more connections.
175 void ResetToAcceptingConnectionState();
176 #endif // defined(OS_POSIX) && !defined(OS_NACL)
178 // Returns true if a named server channel is initialized on the given channel
179 // ID. Even if true, the server may have already accepted a connection.
180 static bool IsNamedServerInitialized(const std::string
& channel_id
);
182 #if defined(OS_LINUX)
183 // Sandboxed processes live in a PID namespace, so when sending the IPC hello
184 // message from client to server we need to send the PID from the global
186 static void SetGlobalPid(int pid
);
190 // Used in Chrome by the TestSink to provide a dummy channel implementation
191 // for testing. TestSink overrides the "interesting" functions in Channel so
192 // no actual implementation is needed. This will cause un-overridden calls to
193 // segfault. Do not use outside of test code!
194 Channel() : channel_impl_(0) { }
197 // PIMPL to which all channel calls are delegated.
199 ChannelImpl
*channel_impl_
;
201 // The Hello message is internal to the Channel class. It is sent
202 // by the peer when the channel is connected. The message contains
203 // just the process id (pid). The message has a special routing_id
204 // (MSG_ROUTING_NONE) and type (HELLO_MESSAGE_TYPE).
206 HELLO_MESSAGE_TYPE
= kuint16max
// Maximum value of message type (uint16),
207 // to avoid conflicting with normal
208 // message types, which are enumeration
209 // constants starting from 0.
215 #endif // IPC_IPC_CHANNEL_H_