[3282] Addes support for full parsing of disable dhcp-ddns entry

D2CLientConfigParser now supports parsing all parameters even if
enable-updates is false.  This allows values like generated-prefix
and qualifying-suffix to be used even if udpates are turned off.
The parser still supports an abbreviated dhcp-ddns entry that has only
enable-updates defined as false.

src/lib/dhcpsrv/dhcp_parsers.cc

@@ -1182,10 +1182,11 @@ D2ClientConfigParser::build(isc::data::ConstElementPtr client_config) {
     }
 
     bool enable_updates = boolean_values_->getParam("enable-updates");
-    if (!enable_updates) {
-        // If it's not enabled, don't bother validating the rest.  This
-        // allows for an abbreviated config entry that only contains
-        // the flag.  The default constructor creates a disabled instance.
+    if (!enable_updates && (client_config->mapValue().size() == 1)) {
+        // If enable-updates is the only parameter and it is false then
+        // we're done.  This allows for an abbreviated configuration entry
+        // that only contains that flag.  Use the default D2ClientConfig
+        // constructor to a create a disabled instance.
         local_client_config_.reset(new D2ClientConfig());
         return;
     }

src/lib/dhcpsrv/tests/dhcp_parsers_unittest.cc

@@ -755,12 +755,12 @@ TEST_F(ParseConfigTest, validD2Config) {
     EXPECT_EQ("test.suffix.", d2_client_config->getQualifyingSuffix());
 
     // Another valid Configuration string.
-    // This one has IPV6 server ip, control flags false,
+    // This one is disabled, has IPV6 server ip, control flags false,
     // empty prefix/suffix
     std::string config_str2 =
         "{ \"dhcp-ddns\" :"
         "    {"
-        "     \"enable-updates\" : true, "
+        "     \"enable-updates\" : false, "
         "     \"server-ip\" : \"2001:db8::\", "
         "     \"server-port\" : 43567, "
         "     \"ncr-protocol\" : \"UDP\", "
@@ -779,13 +779,13 @@ TEST_F(ParseConfigTest, validD2Config) {
     rcode = parseConfiguration(config_str2);
     ASSERT_TRUE(rcode == 0) << error_text_;
 
-    // Verify that DHCP-DDNS is enabled and we can fetch the configuration.
-    EXPECT_TRUE(CfgMgr::instance().ddnsEnabled());
+    // Verify that DHCP-DDNS is disabled and we can fetch the configuration.
+    EXPECT_FALSE(CfgMgr::instance().ddnsEnabled());
     ASSERT_NO_THROW(d2_client_config = CfgMgr::instance().getD2ClientConfig());
     ASSERT_TRUE(d2_client_config);
 
     // Verify that the configuration values are as expected.
-    EXPECT_TRUE(d2_client_config->getEnableUpdates());
+    EXPECT_FALSE(d2_client_config->getEnableUpdates());
     EXPECT_EQ("2001:db8::", d2_client_config->getServerIp().toText());
     EXPECT_EQ(43567, d2_client_config->getServerPort());
     EXPECT_EQ(dhcp_ddns::NCR_UDP, d2_client_config->getNcrProtocol());