[3251] Added an abstract class to handle IPv6 sockets in libdhcp++.

src/lib/dhcp/Makefile.am

@@ -42,6 +42,7 @@ 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 pkt_filter.cc
+libb10_dhcp___la_SOURCES += pkt_filter6.h
 libb10_dhcp___la_SOURCES += pkt_filter_inet.cc pkt_filter_inet.h
 
 if OS_LINUX

src/lib/dhcp/pkt_filter6.h

@@ -0,0 +1,119 @@
+// 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.
+
+#ifndef PKT_FILTER6_H
+#define PKT_FILTER6_H
+
+namespace isc {
+namespace dhcp {
+
+/// Forward declaration to the structure describing a socket.
+struct SocketInfo;
+
+/// Forward declaration to the class representing interface
+class Iface;
+
+/// @brief Abstract packet handling class for DHCPv6.
+///
+/// This class defines methods for performing low level operations on IPv6
+/// socket:
+/// - open socket,
+/// - send DHCPv6 message through the socket,
+/// - receive DHCPv6 through the socket.
+///
+/// Methods exposed by this class are called through the @c IfaceMgr only. They
+/// are not meant to be called directly, except unit testing.
+///
+/// The @c IfaceMgr is responsible for managing the pool of sockets. In
+/// particular, @IfaceMgr detects interfaces suitable to send/receive DHCPv6
+/// messages. When it intends to open a socket on a particular interface, it
+/// will call the PktFilter6::openSocket. If this call is successful, the
+/// structure describing a new socket is returned.
+///
+/// In order to send or receive a DHCPv6 message through this socket,
+/// the @IfaceMgr must use PktFilter6::send or PktFilter6::receive functions of
+/// the same class that has been used to open a socket, i.e. all send/receive
+/// operations should be performed using this particular class.
+///
+/// The major motivation behind creating a separate class, to manage low level
+/// operations using sockets, is to make @c IfaceMgr unit testable. By providing
+/// a stub implementation of this class which mimics the behavior of the real
+/// socket handling class, it is possible to simulate and test various
+/// conditions. For example, the @c IfaceMgr::openSockets function will try to
+/// open sockets on all available interfaces. The test doesn't have any means
+/// to know which interfaces are present. In addition, even if the network
+/// interface detection was implemented on the test side, there is no guarantee
+/// that the particular system has sufficient number of suitable IPv6-enabled
+/// interfaces available for a particular test. Moreover, the test may need
+/// to tweak some of the interface configuration to cover certain test
+/// scenarios. The proposed solution is to not use the actual interfaces
+/// but simply create a pool of fake interfaces which configuration
+/// can be freely modified by a test. This however implies that operations
+/// on sockets must be simulated.
+class PktFilter6 {
+public:
+
+    /// @brief Virtual Destructor.
+    virtual ~PktFilter6() { }
+
+    /// @brief Open a socket.
+    ///
+    /// This function open an IPv6 socket on an interface and binds it to a
+    /// specified UDP port and IP address.
+    ///
+    /// @param iface Interface descriptor.
+    /// @param addr Address on the interface to be used to send packets.
+    /// @param port Port number.
+    ///
+    /// @return A structure describing a primary and fallback socket.
+    virtual SocketInfo openSocket(const Iface& iface,
+                                  const isc::asiolink::IOAddress& addr,
+                                  const uint16_t port) = 0;
+
+    /// @brief Receive DHCPv6 message on the interface.
+    ///
+    /// This function receives a single DHCPv6 message through using a socket
+    /// open on a specified interface.
+    ///
+    /// @param iface interface
+    /// @param socket_info structure holding socket information
+    ///
+    /// @return A pointer to received message.
+    virtual Pkt6Ptr receive(const Iface& iface,
+                            const SocketInfo& socket_info) = 0;
+
+    /// @brief Send DHCPv6 message through a specified interface and socket.
+    ///
+    /// Thie function sends a DHCPv6 message through a specified interface and
+    /// socket. In general, there may be multiple sockets open on a single
+    /// interface as a single interface may have multiple IPv6 addresses.
+    ///
+    /// @param iface Interface to be used to send packet.
+    /// @param sockfd A socket descriptor
+    /// @param pkt A packet to be sent.
+    ///
+    /// @return A result of sending the message. It is 0 if successful.
+    virtual int send(const Iface& iface, uint16_t sockfd,
+                     const Pkt6Ptr& pkt) = 0;
+
+};
+
+
+/// Pointer to a PktFilter object.
+typedef boost::shared_ptr<PktFilter6> PktFilter6Ptr;
+
+} // namespace isc::dhcp
+} // namespace isc
+
+#endif // PKT_FILTER6_H