[2765] Added stub implementation for the function to open fallback socket.

src/lib/dhcp/Makefile.am

@@ -41,7 +41,7 @@ libb10_dhcp___la_SOURCES += option_string.cc option_string.h
 libb10_dhcp___la_SOURCES += protocol_util.cc protocol_util.h
 libb10_dhcp___la_SOURCES += pkt6.cc pkt6.h
 libb10_dhcp___la_SOURCES += pkt4.cc pkt4.h
-libb10_dhcp___la_SOURCES += pkt_filter.h
+libb10_dhcp___la_SOURCES += pkt_filter.h pkt_filter.cc
 libb10_dhcp___la_SOURCES += pkt_filter_inet.cc pkt_filter_inet.h
 
 if OS_LINUX

src/lib/dhcp/pkt_filter.cc

@@ -0,0 +1,29 @@
+// Copyright (C) 2013 Internet Systems Consortium, Inc. ("ISC")
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
+// OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+#include <config.h>
+#include <dhcp/pkt_filter.h>
+
+namespace isc {
+namespace dhcp {
+
+int
+PktFilter::openFallbackSocket(const isc::asiolink::IOAddress&,
+                              const uint16_t) {
+    return (0);
+}
+
+
+} // end of isc::dhcp namespace
+} // end of isc namespace

src/lib/dhcp/pkt_filter.h

@@ -110,6 +110,30 @@ public:
     /// @return result of sending the packet. It is 0 if successful.
     virtual int send(const Iface& iface, uint16_t sockfd,
                      const Pkt4Ptr& pkt) = 0;
+
+protected:
+
+    /// @brief Default implementation to open a fallback socket.
+    ///
+    /// This method provides a means to open a fallback socket and bind it
+    /// to a given IPv4 address and UDP port. This function may be used by the
+    /// derived classes to create a fallback socket. It can be overriden
+    /// in the derived classes if it happens to be insufficient on some
+    /// environments.
+    ///
+    /// The fallback socket is meant to be opened together with the other socket
+    /// (a.k.a. primary socket) used to receive and handle DHCPv4 traffic. The
+    /// traffic received through the fallback should be dropped. The reasoning
+    /// behind opening the fallback socket is explained in the documentation of
+    /// @s isc::dhcp::SocketInfo structure.
+    ///
+    /// @param addr An IPv4 address to bind the socket to.
+    /// @param port A port number to bind socket to.
+    ///
+    /// @return A fallback socket descriptor. This descriptor should be assigned
+    /// to the @c fallbackfd_ field of the @c isc::dhcp::SocketInfo structure.
+    virtual int openFallbackSocket(const isc::asiolink::IOAddress& addr,
+                                   const uint16_t port);
 };
 
 /// Pointer to a PktFilter object.