#1752: added documentation for DNS Client and Server

docs/source/simulation_components/system/dns_client_server.rst

@@ -0,0 +1,56 @@
+.. only:: comment
+
+    © Crown-owned copyright 2023, Defence Science and Technology Laboratory UK
+
+DNS Client Server
+======================
+
+DNS Server
+----------------
+Also known as a DNS Resolver, the ``DNSServer`` provides a DNS Server simulation by extending the base Service class.
+
+Key capabilities
+^^^^^^^^^^^^^^^^
+
+- Simulates DNS requests and DNSPacket transfer across a network
+- Registers domain names and the IP Address linked to the domain name
+- Returns the IP address for a given domain name within a DNS Packet that a DNS Client can read
+- Leverages the Service base class for install/uninstall, status tracking, etc.
+
+Usage
+^^^^^
+- Install on a Node via the ``SoftwareManager`` to start the database service.
+- Service runs on TCP port 53 by default. (TODO: TCP for now, should be UDP in future)
+
+Implementation
+^^^^^^^^^^^^^^
+
+- DNS request and responses use a ``DNSPacket`` object
+- Extends Service class for integration with ``SoftwareManager``.
+
+DNS Client
+---------------
+
+The DNSClient provides a client interface for connecting to the ``DNSServer``.
+
+Key features
+^^^^^^^^^^^^
+
+- Connects to the ``DNSServer`` via the ``SoftwareManager``.
+- Executes DNS lookup requests and keeps a cache of known domain name IP addresses.
+- Handles connection to DNSServer and querying for domain name IP addresses.
+
+Usage
+^^^^^
+
+- Install on a Node via the ``SoftwareManager`` to start the database service.
+- Service runs on TCP port 53 by default. (TODO: TCP for now, should be UDP in future)
+- Execute domain name checks with ``check_domain_exists``, providing a ``DNSServer`` ``IPv4Address``.
+- ``DNSClient`` will automatically add the IP Address of the domain into its cache
+
+Implementation
+^^^^^^^^^^^^^^
+
+- Leverages ``SoftwareManager`` for sending payloads over the network.
+- Provides easy interface for Nodes to find IP addresses via domain names.
+- Extends base Service class.

docs/source/simulation_components/system/software.rst

@@ -17,3 +17,4 @@ Contents
 
    database_client_server
    data_manipulation_bot
+   dns_client_server