[Nel] A small document for your consumption

[Vincent Archer]

While waiting for the whole load, here's a quick and short document. Look
at it, and critique your hearts out...

Client server connect

This document describes quickly the connection process of a client to a world
running a NeL-based system.

Abbreviations
-------------

LS: The login service (one overall)
WS: The welcome service (one for each world)
FES: The front-end service (N per world)

Steps
-----

1: The client initiates a connection to the login service, using the supplied
   IP and port from the configuration file, with the help of the DNS for IP
   resolution.

   Note: DNS spoofing or configuration file modification can lead to LS
   spoofing and hacking of the login/password information of the client.
   However, DNS is needed for flexibility of the login service location.

2: The client submits its login, password, and system capabilities.

3: The LS checks the login/password validity, and builds the list of all
   available worlds according to account information and current system
   settings. This list contains world names and the IP for the WS of that
   world.

   Note: DNS is not used in that step.

4: The client selects the world it wants to log on, and submits the IP address
   of its world service to the LS.

5: The LS sends a notification to the selected WS of the client's connection
   desires. It generates and submits a single-use cookie to validate the
   incoming connection.

   Note: The cookie includes the client's IP, as seen by the LS (to avoid
   address translation problems) for validation.

6: The WS selects a FES to accept the client connexion, and submits the cookie
   to the FES.

7: The FES acknowledges its capacity to accept the client to the WS.

8: The WS acknowledges its capacity to accept the client to the LS, and
   indicates the IP/port of the selected FES.

9: The LS acknowledges the login request to the client, and indicates the
   IP/port of the selected FES.

10: The client disconnects from the LS.

11: The client initiates a connection to the indicated FES.

12: The client sends the submitted cookie to the FES.

13: The FES validates and acknowledges the cookie.

Side notes
----------

Whenever a world starts, the WS establishes a permanent link with the LS,
using an encrypted link (it is assumed that the LS and WS are located on two
physically and probably geographically distinct networks). A 'SHARD' message
serves as authentification, and the WS then updates the LS with its state,
name and IP address. The WS may have a list of valid IP/port address for WS
to avoid the occasional pirate server registration.

-- 
Vincent Archer                                         Email: address@hidden

Nevrax France.                              Off on the yellow brick road we go!