GServer

Note: This README is a work in progress 🛠️

A rudimentary TCP/UDP game server mimicking the architecture of Graal Online's GServer from the 90s-00s.

Networking

Packets are sent between the client and server to enable communication. Specific packets can carry data specific purposes, referred to as messages. A message has an ID that defines its type/purpose, as well as data related to its purpose.

The first byte of a message is used to denote its type, but no standard format is shared between messages for the data belonging to each message.

For example: when authenticating, the following message is used:

• Message ID (1 byte)
• Username length (1 byte)
• Username (x bytes, according to the username length)
• Password length (1 byte)
• Password (x bytes, according to the password length)

{message_id}{username_len}{username}{password_len}{password}

(see Messages section for this message and others' ASN.1 definitions)

All possible client and server message IDs can be found in Networking/Enums/ClientPacketIn.cs or Networking/Enums/ServerPacketIn.cs, according to whether the message is being received (in) or transmitted (out)

Messages

AuthMessage

AuthMessage ::= SEQUENCE {
    messageId   INTEGER (0..255),
    usernameLen INTEGER (0..255),
    username    OCTET STRING (SIZE (0..usernameLen)),
    passwordLen INTEGER (0..255),
    password    OCTET STRING (SIZE (0..passwordLen))
}

ListServerMessage (TODO)

ServerListingBlock ::= SEQUENCE {
    name        OCTET STRING (SIZE (50)),
    description OCTET STRING (SIZE (1000)),
    playercount INTEGER (0..65535),
    ip          OCTET STRING (SIZE (15)),
    port        INTEGER (0..65535),
    serverTier  INTEGER (0..255)
}

ServerListing ::= SEQUENCE {
    messageId   INTEGER (0..255),
    ...
}

Projects

The repo is made up of the following projects:

• GServer.Server - the server to be connected to
• GServer.Client - the client that connects to the server
• GServer.Common - a class library used by both of the above projects. Contains shared code.