Add an implementation for async_network_alive to Linux

chrome/browser/sync/notifier/base/linux/async_network_alive_linux.cc

+// Copyright (c) 2010 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.
+
+#include "chrome/browser/sync/notifier/base/async_network_alive.h"
+
+#include <sys/socket.h>
+#include <asm/types.h>
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
+
+#include "base/logging.h"
+#include "talk/base/physicalsocketserver.h"
+
+namespace notifier {
+
+class AsyncNetworkAliveLinux : public AsyncNetworkAlive {
+ public:
+  AsyncNetworkAliveLinux() {
+    if (pipe(exit_pipe_) == -1) {
+      PLOG(ERROR) << "Could not create pipe for exit signal.";
+      exit_pipe_[0] = 0;
+      exit_pipe_[1] = 0;
+    }
+  }
+
+  virtual ~AsyncNetworkAliveLinux() {
+    if (exit_pipe_[1]) {
+      close(exit_pipe_[1]);
+    }
+  }
+
+ protected:
+  // SignalThread Interface
+  virtual void DoWork() {
+    if (!exit_pipe_[0]) {
+      // If we don't have an exit flag to listen for, set the error flag and
+      // abort.
+      error_ = true;
+      return;
+    }
+
+    // This function listens for changes to network interfaces, and link state.
+    // It's copied from syncapi.cc.
+    struct sockaddr_nl socket_address;
+
+    memset(&socket_address, 0, sizeof(socket_address));
+    socket_address.nl_family = AF_NETLINK;
+    socket_address.nl_groups = RTMGRP_LINK | RTMGRP_IPV4_IFADDR;
+
+    // NETLINK_ROUTE is the protocol used to update the kernel routing table.
+    int fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
+    bind(fd, (struct sockaddr *) &socket_address, sizeof(socket_address));
+
+    fd_set rdfs;
+    FD_ZERO(&rdfs);
+    FD_SET(fd, &rdfs);
+    FD_SET(exit_pipe_[0], &rdfs);
+
+    int max_fd = fd > exit_pipe_[0] ? fd : exit_pipe_[0];
+
+    int result = select(max_fd + 1, &rdfs, NULL, NULL, NULL);
+
+    if (result <= 0) {
+      error_ = true;
+      PLOG(ERROR) << "select() returned unexpected result " << result;
+      close(fd);
+      close(exit_pipe_[0]);
+      return;
+    }
+
+    // Since we recieved a change from the socket, read the change in.
+    if (FD_ISSET(fd, &rdfs)) {
+      char buf[4096];
+      struct iovec iov = { buf, sizeof(buf) };
+      struct sockaddr_nl sa;
+
+      struct msghdr msg = { (void *)&sa, sizeof(sa), &iov, 1, NULL, 0, 0 };
+      recvmsg(fd, &msg, 0);
+    }
+
+    close(fd);
+
+    // If exit_pipe was written to, we must be shutting down.
+    if (FD_ISSET(exit_pipe_[0], &rdfs)) {
+      alive_ = false;
+      error_ = true;
+      close(exit_pipe_[0]);
+      return;
+    }
+
+    // If there is an active connection, check that talk.google.com:5222
+    // is reachable.
+    talk_base::PhysicalSocketServer physical;
+    scoped_ptr<talk_base::Socket> socket(physical.CreateSocket(SOCK_STREAM));
+    if (socket->Connect(talk_base::SocketAddress("talk.google.com", 5222))) {
+      alive_ = false;
+    } else {
+      alive_ = true;
+    }
+  }
+
+  virtual void OnWorkStop() {
+    if (exit_pipe_[1]) {
+      char data = 0;
+      // We can't ignore the return value on write(), since that generates a
+      // compile warning.  However, since we're exiting, there's nothing we can
+      // do if this fails except to log it.
+      if (write(exit_pipe_[1], &data, 1) == -1) {
+        PLOG(WARNING) << "Error sending error signal to AsyncNetworkAliveLinux";
+      }
+    }
+  }
+
+ private:
+  int exit_pipe_[2];
+  DISALLOW_COPY_AND_ASSIGN(AsyncNetworkAliveLinux);
+};
+
+AsyncNetworkAlive* AsyncNetworkAlive::Create() {
+  return new AsyncNetworkAliveLinux();
+}
+
+}  // namespace notifier