Default listening port: 2000.
As per protocol described in:
RFC 'CHAT UDP'
In order to use the server a user must be logged on with a unique id/username.
This was implemented using a multithreaded architecture: when a packet is received the main execute thread creates a separate thread to handle it.
--------------------------------
| OPCODE | LENGTH | DATA |
--------------------------------
01 bytes 02 bytes n bytes
0.1 'OK' -> Procedure completed correctly
-------------
| 0 | 0 |
-------------
0.2 'Error' -> An error was encountered during the completion of procedure
------------------------------------------
| 01 | * | ERROR_DESCRIPTION_STRING |
------------------------------------------
1.1 Client to server registration
--------------------------------
| 11 | LENGTH | USERNAME |
--------------------------------
1.2 Server to client response:
'OK' -> Procedure completed correctly, username was added to user list.
Packet format as described in '0.1'
'Error' -> User hasn't been added because of error.
Possible errors are: username is already present, username is invalid.
Packet format as described in '0.2'
2.1 Client to server disconnection
Client sends disconnection request to the server.
--------------
| 12 | 00 |
--------------
2.2 Disconnection Acknowledgment
The server, after deleting the client's username from the user-list responds with 'OK'. Format as described in 0.1.
3.1 Client server information request, to test status.
---------------
| 40 | 00 |
---------------
3.2 Server information response: server date and version.
-------------------------------------------
| 41 | LENGTH | SERVER_DATE_VERSION |
-------------------------------------------
3.3 Client list request
---------------
| 42 | 00 |
---------------
3.4 Server list
Server sends list of users, if prompted by client request and at regular intervals
----------------------------------------------------------------
| 43 | LENGTH | USER_1 | 0 | USER_2 | 0 | USER_N |
----------------------------------------------------------------
4.1 Client sends 'broadcast' message to all users.
------------------------------
| 20 | LENGTH | MESSAGE |
------------------------------
4.2 Server forwards packet to all connected users (Including sender).
-------------------------------------------
| 21 | * | SENDER | 0 | MESSAGE |
-------------------------------------------
5.1 Client sends message to server, addressed to specific user.
--------------------------------------------
| 22 | * | RECEIVER | 0 | MESSAGE |
--------------------------------------------
5.2 Server forwards message to specified user.
-------------------------------------------
| 23 | * | SENDER | 0 | MESSAGE |
-------------------------------------------
Server to sender response:
'OK' -> Procedure completed correctly, destination user is present in list.
Packet format as described in '0.1'
'Error' -> Procedure not completed, destination user wasn't found in list.
Possible errors are: username is already present, username is invalid.
Packet format as described in '0.2'
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