[master] Merge branch 'trac3794' (packet statistics in DHCPv4)

diff --cc doc/guide/dhcp4-srv.xml
Simple merge

diff --cc src/bin/dhcp4/dhcp4_srv.cc
Simple merge

diff --cc src/bin/dhcp4/dhcp4_srv.h
Simple merge

diff --cc src/bin/dhcp4/tests/Makefile.am
Simple merge

diff --cc src/bin/dhcp4/tests/dhcp4_client.cc
Simple merge

diff --cc src/bin/dhcp4/tests/dhcp4_srv_unittest.cc
Simple merge

diff --cc src/bin/dhcp4/tests/dora_unittest.cc
index ca7c2f7d2aa992691316cc7f94e983f28d567abc,b92a36ab063a9ba97b13a4480cd5eaafd0d4fef9..36f3090fc342b0313b7c68fa35120ebd72375436
--- 1/src/bin/dhcp4/tests/dora_unittest.cc
--- 2/src/bin/dhcp4/tests/dora_unittest.cc
+++ b/src/bin/dhcp4/tests/dora_unittest.cc
@@@ -198,32 -172,84 +199,43 @@@ public
          : Dhcpv4SrvTest(),
            iface_mgr_test_config_(true) {
          IfaceMgr::instance().openSockets4();
+ 
+         // Let's wipe all existing statistics.
+         isc::stats::StatsMgr::instance().removeAll();
+     }
+ 
+     /// @brief Desctructor.
+     ///
+     /// Cleans up statistics after the test.
+     ~DORATest() {
+         // Let's wipe all existing statistics.
+         isc::stats::StatsMgr::instance().removeAll();
      }
  
 -    /// @brief Test that server doesn't allocate the lease for a client
 -    /// which has the same address or client identifier as another client.
 +    /// @brief Test that server returns the same lease for the client which is
 +    /// sometimes using client identifier, sometimes not.
      ///
      /// This test checks the server's behavior in the following scenario:
 -    /// - Client A identifies itself to the server using the hardware address
 -    ///   and client identifier or only one of those.
 -    /// - Client A performs the 4-way exchange and obtains a lease from the server.
 -    /// - Client B uses the same HW address or client identifier as the client A.
 -    /// - Client B uses both HW address and client identifier if the client A is using
 -    ///   only one of them. Client B uses one of the HW address or client
 -    ///   identifier if the client A is using both.
 -    /// - Client B sends the DHCPDISCOVER to the server.
 -    ///   The server determines that there is a lease for the client A using the
 -    ///   same HW address as the client B. Server discards the client's message and
 -    ///   doesn't offer the lease for the client B to prevent allocation of the
 -    ///   lease without a unique identifier.
 -    /// - The client sends the DHCPREQUEST and the server sends the DHCPNAK for the
 -    ///   same reason.
 -    /// - The client A renews its address successfully.
 +    /// - Client identifies itself to the server using HW address, and may use
 +    ///   client identifier.
 +    /// - Client performs the 4-way exchange and obtains a lease from the server.
 +    /// - If the client identifier was in use when the client has acquired the lease,
 +    ///   the client uses null client identifier in the next exchange with the server.
 +    /// - If the client identifier was not in use when the client has acquired the
 +    ///   lease, the client uses client identifier in the next exchange with the
 +    ///   server.
 +    /// - When the client contacts the server for the second time using the
 +    ///   DHCPDISCOVER the server determines (using HW address) that the client
 +    ///   already has a lease and returns this lease to the client.
 +    /// - The client renews the existing lease.
      ///
 -    /// The specific test cases using this test must make sure that one of the
 -    /// provided parameters is an empty string. This simulates the situation where
 -    /// one of the clients has only one of the identifiers and the other one has
 -    /// two.
 -    ///
 -    /// @param hwaddr_a HW address of client A.
 -    /// @param clientid_a Client id of client A.
 -    /// @param hwaddr_b HW address of client B.
 -    /// @param clientid_b Client id of client B.
 -    void oneAllocationOverlapTest(const std::string& hwaddr_a,
 -                                  const std::string& clientid_a,
 -                                  const std::string& hwaddr_b,
 +    /// @param clientid_a Client identifier when the client initially allocates
 +    /// the lease. An empty value means "no client identifier".
 +    /// @param clientid_b Client identifier when the client sends the DHCPDISCOVER
 +    /// and then DHCPREQUEST to renew lease.
 +    void oneAllocationOverlapTest(const std::string& clientid_a,
                                    const std::string& clientid_b);
  
 -    /// @brief Test that server can allocate the lease for a client having
 -    /// the same HW Address or client id as another client.
 -    ///
 -    /// This test checks the server behavior in the following situation:
 -    /// - Client A identifies itself to the server using client identifier
 -    ///   and the hardware address and requests allocation of the new lease.
 -    /// - Server allocates the lease to the client.
 -    /// - Client B has a different hardware address or client identifier than
 -    ///   the client A, but the other identifier is equal to the corresponding
 -    ///   identifier of the client A.
 -    /// - Client B sends DHCPDISCOVER.
 -    /// - Server should determine that the client B is not client A, because
 -    ///   it is using a different hadrware address or client identifier.
 -    ///   As a consequence, the server should offer a different address to the
 -    ///   client B.
 -    /// - The client B performs the 4-way exchange again, and the server
 -    ///   allocates a new address to the client, which should be different
 -    ///   than the address used by the client A.
 -    /// - Client B is in the renewing state and it successfully renews its
 -    ///   address.
 -    /// - The client A also renews its address successfully.
 -    ///
 -    /// @param hwaddr_a HW address of client A.
 -    /// @param clientid_a Client id of client A.
 -    /// @param hwaddr_b HW address of client B.
 -    /// @param clientid_b Client id of client B.
 -    void twoAllocationsOverlapTest(const std::string& hwaddr_a,
 -                                   const std::string& clientid_a,
 -                                   const std::string& hwaddr_b,
 -                                   const std::string& clientid_b);
 -
      /// @brief Interface Manager's fake configuration control.
      IfaceMgrTestConfig iface_mgr_test_config_;
  

diff --cc src/lib/dhcp/pkt4.cc
Simple merge