NCID Client, Gateway, and Server Protocol

Last modified by jlc on Fri May 23, 2008

The NCID-FORMAT file explains the lines sent to the client by the server.
It also explains lines sent by a gateway to the server.

Client Implementation:
        - connect to port 3333.
        - receive a connect line that identifies the server
        - possibly receive multiple CIDLOG lines (only at connect)
        - possibly receive a server MSG line
        - possibly receive a CIDINFO line at each ring
        - receive a CID line whenever a call comes in
        - ignore lines that do not begin with:
          200
          CID:
          CIDLOG:
          MSG:
          MSGLOG:
          CIDINFO:
        - parse CID and CIDLOG lines based on name fields, so if fields
          are added, the client will still work
        - clients are allowed to connect and disconnect as they please
        - clients are allowed to send a text message to the server

Gateway Implementation:
        - connect to port 3333.
        - read and ignore all lines from the server, including:
          a connect line that identifies the server
          and CIDLOG, MSGLOG, CID, and MSG lines
        - connect to Caller ID service
        - when CID information is obtained from the service, send the
          data to the server in the CALL data Line format
        - if hangup detected before answer, send the data to the server
          in the CALLINFO CANCEL line format
        - if hangup detected after answer, send the data to the server
          in the CALLINFO BYE Line format
        - If outgoing call is detected, send the data to the server
          in the CALLINFO CALLED Line forma

Server Implementation:
        - listen to port 3333 for a connection,
        - send a connect line to identify the server
        - if configured, send CIDLOG and MSGLOG lines when a client connects
          these are the CID: and MSG: lines in cidcall.log
        - send a CID line when a call is received to connected clients
        - send a MSG line with important information, if needed
        - send a CIDINFO line at each ring with a line indicator (default -)
          and the ring count
        - send a CIDINFO line after ringing stops, with a ring count of 0
        - maintain a constant TCP connection with the clients
        - detect clients as they come and go
	    - if client sends text, sent it to all connected clients
	    - if gateway sends a line prefixed with CALL: treat it as CID data
          from a device
        - if a gateway sends a line prefixed with CALLINFO: process
          CANECEL as a ring count of -1, and BYE as a ring count of -2