[5058] CSV lease file loading now emits error log for each invalid row

src/bin/lfc/tests/lfc_controller_unittests.cc
    Fixed test data

src/lib/dhcpsrv/dhcpsrv_messages.mes
    added new error log message DHCPSRV_MEMFILE_LEASE_LOAD_ROW_ERROR

src/lib/dhcpsrv/lease_file_loader.h
    LeaseFileLoader::load() - new emits a error log for each row that
    fails to load

src/bin/lfc/tests/lfc_controller_unittests.cc

@@ -407,8 +407,9 @@ TEST_F(LFCControllerTest, launch4) {
     string b_3 = "192.0.3.15,dd:de:ba:0d:1b:2e:3e:4f,0a:00:01:04,"
                  "100,150,7,0,0,,1\n";
 
+    // This one should be invalid, no hardware address and state is not declined
     string c_1 = "192.0.2.3,,a:11:01:04,"
-                 "200,200,8,1,1,host.example.com,1\n";
+                 "200,200,8,1,1,host.example.com,0\n";
 
     string d_1 = "192.0.2.5,16:17:18:19:1a:bc,,"
                  "200,200,8,1,1,host.example.com,1\n";

src/lib/dhcpsrv/dhcpsrv_messages.mes

@@ -459,6 +459,12 @@ replaced by those read from the file.
 % DHCPSRV_MEMFILE_LEASE_LOAD loading lease %1
 A debug message issued when DHCP lease is being loaded from the file to memory.
 
+% DHCPSRV_MEMFILE_LEASE_LOAD_ROW_ERROR discarding row %1, error: %2
+An error message issued the the DHCP lease being loaded from the given row of
+the lease file fails. The log message should contain the specific reason the
+row was discarded. The server will continue loading the remaining data.
+This may indicate a corrupt lease file.
+
 % DHCPSRV_MEMFILE_LFC_EXECUTE executing Lease File Cleanup using: %1
 An informational message issued when the Memfile lease database backend
 starts a new process to perform Lease File Cleanup.

src/lib/dhcpsrv/lease_file_loader.h

@@ -91,6 +91,10 @@ public:
         while (true) {
             // Unable to parse the lease.
             if (!lease_file.next(lease)) {
+                LOG_ERROR(dhcpsrv_logger, DHCPSRV_MEMFILE_LEASE_LOAD_ROW_ERROR)
+                            .arg(lease_file.getReads())
+                            .arg(lease_file.getReadMsg());
+
                 // A value of 0xFFFFFFFF indicates that we don't return
                 // until the whole file is parsed, even if errors occur.
                 // Otherwise, check if we have exceeded the maximum number