[#642,!373] Addressed review comments.

- Don't allow for deleting logical server 'all'.
- Additional tests to make sure that other servers aren't affected by deletion.
- Added note that getAll() doesn't return logical server all.

src/hooks/dhcp/mysql_cb/mysql_cb_dhcp4.cc

@@ -2846,7 +2846,7 @@ MySqlConfigBackendDHCPv4::deleteServer4(const ServerTag& server_tag) {
         .arg(server_tag.get());
     uint64_t result = impl_->deleteServer(MySqlConfigBackendDHCPv4Impl::CREATE_AUDIT_REVISION,
                                           MySqlConfigBackendDHCPv4Impl::DELETE_SERVER4,
-                                          server_tag.get());
+                                          server_tag);
     LOG_DEBUG(mysql_cb_logger, DBGLVL_TRACE_BASIC, MYSQL_CB_DELETE_SERVER4_RESULT)
         .arg(result);
     return (result);

src/hooks/dhcp/mysql_cb/mysql_cb_dhcp4.h

@@ -227,6 +227,9 @@ public:
 
     /// @brief Retrieves all servers.
     ///
+    /// This method returns the list of servers excluding the logical server
+    /// 'all'.
+    ///
     /// @return Collection of servers from the backend.
     virtual db::ServerCollection
     getAllServers4() const;
@@ -480,6 +483,8 @@ public:
     ///
     /// @param server_tag Tag of the server to be deleted.
     /// @return Number of deleted servers.
+    /// @throw isc::InvalidOperation when trying to delete the logical
+    /// server 'all'.
     virtual uint64_t
     deleteServer4(const data::ServerTag& server_tag);
 

src/hooks/dhcp/mysql_cb/mysql_cb_dhcp6.cc

@@ -3233,7 +3233,7 @@ MySqlConfigBackendDHCPv6::deleteServer6(const ServerTag& server_tag) {
         .arg(server_tag.get());
     uint64_t result = impl_->deleteServer(MySqlConfigBackendDHCPv6Impl::CREATE_AUDIT_REVISION,
                                           MySqlConfigBackendDHCPv6Impl::DELETE_SERVER6,
-                                          server_tag.get());
+                                          server_tag);
     LOG_DEBUG(mysql_cb_logger, DBGLVL_TRACE_BASIC, MYSQL_CB_DELETE_SERVER6_RESULT)
         .arg(result);
     return (result);

src/hooks/dhcp/mysql_cb/mysql_cb_dhcp6.h

@@ -227,6 +227,9 @@ public:
 
     /// @brief Retrieves all servers.
     ///
+    /// This method returns the list of servers excluding the logical server
+    /// 'all'.
+    ///
     /// @return Collection of servers from the backend.
     virtual db::ServerCollection
     getAllServers6() const;
@@ -513,6 +516,8 @@ public:
     ///
     /// @param server_tag Tag of the server to be deleted.
     /// @return Number of deleted servers.
+    /// @throw isc::InvalidOperation when trying to delete the logical
+    /// server 'all'.
     virtual uint64_t
     deleteServer6(const data::ServerTag& server_tag);
 

src/hooks/dhcp/mysql_cb/mysql_cb_impl.cc

@@ -964,7 +964,14 @@ MySqlConfigBackendImpl::createUpdateServer(const int& create_audit_revision,
 uint64_t
 MySqlConfigBackendImpl::deleteServer(const int& create_audit_revision,
                                      const int& delete_index,
-                                     const std::string& server_tag) {
+                                     const ServerTag& server_tag) {
+
+    // It is not allowed to delete 'all' logical server.
+    if (server_tag.amAll()) {
+        isc_throw(InvalidOperation, "'all' is a name reserved for the server tag which"
+                  " associates the configuration elements with all servers connecting"
+                  " to the database and can't be deleted");
+    }
 
     MySqlTransaction transaction(conn_);
 
@@ -976,7 +983,7 @@ MySqlConfigBackendImpl::deleteServer(const int& create_audit_revision,
 
     // Specify which server should be deleted.
     MySqlBindingCollection in_bindings = {
-        MySqlBinding::createString(server_tag)
+        MySqlBinding::createString(server_tag.get())
     };
 
     // Attempt to delete the server.

src/hooks/dhcp/mysql_cb/mysql_cb_impl.h

@@ -655,8 +655,10 @@ public:
     /// @param create_index Index of the DELETE query to be executed.
     /// @param server_tag Tag of the server to be deleted.
     /// @return Number of deleted servers.
+    /// @throw isc::InvalidOperation when trying to delete the logical
+    /// server 'all'.
     uint64_t deleteServer(const int& create_audit_revision, const int& index,
-                          const std::string& server_tag);
+                          const data::ServerTag& server_tag);
 
     /// @brief Attempts to delete all servers.
     ///

src/hooks/dhcp/mysql_cb/tests/mysql_cb_dhcp4_unittest.cc

@@ -506,6 +506,12 @@ TEST_F(MySqlConfigBackendDHCPv4Test, createUpdateDeleteServer) {
     EXPECT_NO_THROW(servers_deleted = cbptr_->deleteServer4(ServerTag("server2")));
     EXPECT_EQ(0, servers_deleted);
 
+    // Make sure that the server1 wasn't deleted.
+    EXPECT_NO_THROW(returned_server = cbptr_->getServer4(ServerTag("server1")));
+    EXPECT_TRUE(returned_server);
+
+    // Deleting logical server 'all' is not allowed.
+    EXPECT_THROW(cbptr_->deleteServer4(ServerTag()), isc::InvalidOperation);
 
     // Delete the existing server.
     EXPECT_NO_THROW(servers_deleted = cbptr_->deleteServer4(ServerTag("server1")));

src/hooks/dhcp/mysql_cb/tests/mysql_cb_dhcp6_unittest.cc

@@ -547,6 +547,12 @@ TEST_F(MySqlConfigBackendDHCPv6Test, createUpdateDeleteServer) {
     EXPECT_NO_THROW(servers_deleted = cbptr_->deleteServer6(ServerTag("server2")));
     EXPECT_EQ(0, servers_deleted);
 
+    // Make sure that the server1 wasn't deleted.
+    EXPECT_NO_THROW(returned_server = cbptr_->getServer6(ServerTag("server1")));
+    EXPECT_TRUE(returned_server);
+
+    // Deleting logical server 'all' is not allowed.
+    EXPECT_THROW(cbptr_->deleteServer6(ServerTag()), isc::InvalidOperation);
 
     // Delete the existing server.
     EXPECT_NO_THROW(servers_deleted = cbptr_->deleteServer6(ServerTag("server1")));

src/lib/dhcpsrv/config_backend_dhcp4.h

@@ -231,6 +231,9 @@ public:
 
     /// @brief Retrieves all servers.
     ///
+    /// This method returns the list of servers excluding the logical server
+    /// 'all'.
+    ///
     /// @return Collection of servers from the backend.
     virtual db::ServerCollection
     getAllServers4() const = 0;

src/lib/dhcpsrv/config_backend_dhcp6.h

@@ -232,6 +232,9 @@ public:
 
     /// @brief Retrieves all servers.
     ///
+    /// This method returns the list of servers excluding the logical server
+    /// 'all'.
+    ///
     /// @return Collection of servers from the backend.
     virtual db::ServerCollection
     getAllServers6() const = 0;

src/lib/dhcpsrv/config_backend_pool_dhcp4.h

@@ -235,6 +235,9 @@ public:
 
     /// @brief Retrieves all servers from the particular backend.
     ///
+    /// This method returns the list of servers excluding the logical server
+    /// 'all'.
+    ///
     /// @param backend_selector Backend selector.
     /// @return Collection of servers from the backend.
     virtual db::ServerCollection

src/lib/dhcpsrv/config_backend_pool_dhcp6.h

@@ -234,6 +234,9 @@ public:
 
     /// @brief Retrieves all servers from the particular backend.
     ///
+    /// This method returns the list of servers excluding the logical server
+    /// 'all'.
+    ///
     /// @param backend_selector Backend selector.
     /// @return Collection of servers from the backend.
     virtual db::ServerCollection