shill: LinkMonitor: Add ArpClient code

Add ArpClient class and start hooking it up to LinkMonitor.

BUG=chromium-os:32600
TEST=Unit tests.  Some real-world testing using the test harness
to transmit and receive ARP on a real network.

Change-Id: Ic05d8d7eb921878e3776f35b4be285554ef86456
Reviewed-on: https://gerrit.chromium.org/gerrit/28148
Commit-Ready: Paul Stewart <pstew@chromium.org>
Reviewed-by: Paul Stewart <pstew@chromium.org>
Tested-by: Paul Stewart <pstew@chromium.org>
diff --git a/mock_sockets.h b/mock_sockets.h
index b095ce9..f366e7f 100644
--- a/mock_sockets.h
+++ b/mock_sockets.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
+// Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
@@ -19,6 +19,7 @@
 
   MOCK_METHOD3(Accept,
                int(int sockfd, struct sockaddr *addr, socklen_t *addrlen));
+  MOCK_METHOD2(AttachFilter, int(int sockfd, struct sock_fprog *pf));
   MOCK_METHOD3(Bind,
                int(int sockfd, const struct sockaddr *addr, socklen_t addrlen));
   MOCK_METHOD2(BindToDevice, int(int sockfd, const std::string &device));
@@ -31,6 +32,12 @@
   MOCK_METHOD1(GetSocketError, int(int fd));
   MOCK_METHOD3(Ioctl, int(int d, int request, void *argp));
   MOCK_METHOD2(Listen, int(int d, int backlog));
+  MOCK_METHOD6(RecvFrom, ssize_t(int sockfd,
+                                 void *buf,
+                                 size_t len,
+                                 int flags,
+                                 struct sockaddr *src_addr,
+                                 socklen_t *addrlen));
   MOCK_METHOD4(Send,
                ssize_t(int sockfd, const void *buf, size_t len, int flags));
   MOCK_METHOD6(SendTo, ssize_t(int sockfd,