Accept inbound connections on unix domain socket

mojo/shell/incoming_connection_listener.h

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MOJO_SHELL_INCOMING_CONNECTION_LISTENER_H_
+#define MOJO_SHELL_INCOMING_CONNECTION_LISTENER_H_
+
+#include "base/callback_forward.h"
+#include "base/files/file_path.h"
+#include "base/memory/weak_ptr.h"
+#include "base/threading/thread_checker.h"
+#include "net/socket/socket_descriptor.h"
+#include "net/socket/unix_domain_server_socket_posix.h"
+
+namespace mojo {
+namespace shell {
+
+// Asynchronously listens for incoming connections on a unix domain
+// socket at the provided path. Expects the parent directory in the
+// path to exist.  Must be run on an IO thread.
+class IncomingConnectionListener {
+ public:
+  class Delegate {
+   public:
+    Delegate();
+    virtual ~Delegate();
+
+    // Called when listening has started. rv is from net/base/net_error_list.h
+    virtual void OnListening(int rv) = 0;
+
+    // Called every time an incoming connection is accepted. The delegate
+    // takes ownership of incoming.
+    virtual void OnConnection(net::SocketDescriptor incoming) = 0;
+  };
+
+  IncomingConnectionListener(const base::FilePath& socket_path,
+                             Delegate* delegate);
+  virtual ~IncomingConnectionListener();
+
+  // Attempts to bind a unix domain socket, set up for listening, at
+  // socket_path_.
+  // Regardless of success or failure, calls delegate->OnListening() with a
+  // status code. If the socket was successfully created, begins asynchronously
+  // waiting to accept incoming connections.
+  void StartListening();
+
+ private:
+  // Tells listen_socket_ to perform a non-blocking accept(). It may succeed
+  // or fail immediately, or asynchronously wait for a later connection attempt.
+  // Regardless, when it returns a definitive result (OK or a failing error),
+  // calls OnAccept().
+  void Accept();
+
+  // If rv indicates success, incoming_socket_ should be populated with a
+  // connected FD. Hands this off to delegate->OnConnection() and goes
+  // back to non-blocking accept().
+  // Upon error, logs the error and goes back to non-blocking accept().
+  void OnAccept(int rv);
+
+  Delegate* const delegate_;
+
+  const base::FilePath socket_path_;
+  net::UnixDomainServerSocket listen_socket_;
+  base::ThreadChecker listen_thread_checker_;
+
+  net::SocketDescriptor incoming_socket_;
+
+  base::WeakPtrFactory<IncomingConnectionListener> weak_ptr_factory_;
+};
+
+}  // namespace shell
+}  // namespace mojo
+
+#endif  // MOJO_SHELL_INCOMING_CONNECTION_LISTENER_H_