Reflector Messages

Overview

Reflectors generate 2 basic types of text messages for display to clients: the Message Of The Day (MOTD) and disconnect messages.

The MOTD is transmitted once to all clients when they first connect, and includes any information that the reflector operator wishes to display to the client. There are no mechanisms for retransmission in the event of packet loss. Once a MOTD packet has been received by a client, additional MOTD packets are ignored until a new connection is initiated.

Disconnect messages are generated by various conditions on the reflector, such as admission control failure. A disconnect message is displayed to the client and causes the connection to be terminated. There are no mechanisms for retransmission in the event of packet loss; presumably the condition that generated the original message will generate a repetition if the original is lost. Once a disconnect message has been received by a client, additional disconnect messages are ignored until a new connection is initiated.

These two kinds messages are distinguished by having a different Data Type and a slightly different packet format.

MOTD Packet Format

    0              8              16             24            31
    +--------------+--------------+--------------+--------------+
    |                 CU-SeeMe Header                           |
    |                         (26 bytes)                        |
    |                            ...                            |
    |                             +--------------+--------------+
    |                             |            Unused           |
    +--------------+--------------+--------------+--------------+
1Ch |            Length           |       MOTD Text....         |
    +--------------+--------------+                             |
    |                          .....                            |
    |                       ....                                |
    +--------------+--------------+--------------+--------------+
00h - CU-SeeMe Header (26 bytes)
With Data Type = kMOTDType = 105

1Ch - Length (2 bytes - unsigned integer)
The number of characters contained in the MOTD text.

1Eh - MOTD Text (Length bytes - character)
The text to be displayed in the Message of the Day dialog.

Disconnect Message Packet Format 

    0              8              16             24            31
    +--------------+--------------+--------------+--------------+
    |                 CU-SeeMe Header                           |
    |                         (26 bytes)                        |
    |                            ...                            |
    |                             +--------------+--------------+
    |                             |            Unused           |
    +--------------+--------------+--------------+--------------+
1Ch |    Length    |              Message Text....              |
    +--------------+                                            |
    |                          .....                            |
    |                       ....                                |
    +--------------+--------------+--------------+--------------+
00h - CU-SeeMe Header (26 bytes)
With Data Type = kMessageType = 104

1Ch - Length (1 byte - unsigned integer)
The number of characters contained in the message text.

1Dh - Message Text (Length bytes - character)
The text to be displayed in the disconnection dialog.