moo.shell.iac

IAC (telnet subnegotiation) parser, encoder, and per-session negotiator.

DjangoMOO speaks SSH, not telnet. This module is the in-band channel that MUD-client protocols (GMCP, MSSP, MTTS, MSP, …) ride on top of. Clients that connect via sshelnet get raw 0xFF-prefixed IAC sequences passed through transparently.

Scope: just the IAC framing layer plus the MUD-accessibility protocols listed in issue #16. We do not implement the wider telnet spec (NAWS, ECHO, SGA, line-mode, etc.).

Byte plumbing

asyncssh channels default to UTF-8 encoding in both directions. 0xFF is invalid UTF-8, so the SSH server reconfigures the channel to encoding=None (bytes mode) on connect and handles text encoding itself: outbound Rich/ prompt_toolkit strings are UTF-8 encoded in the shell layer before reaching _chan.write, and inbound bytes are decoded after the IAC parser strips any subnegotiation frames.

Functions

`encode_charset_accepted`(charset)	Server reply to a client CHARSET REQUEST.
`encode_charset_rejected`()
`encode_charset_request`(charsets[, sep])	Server-initiated CHARSET REQUEST subnegotiation.
`encode_cmd`(cmd, opt)	Encode IAC WILL/WONT/DO/DONT <opt>.
`encode_eor`()
`encode_ga`()
`encode_gmcp`(module, data)	Encode a GMCP subnegotiation frame for the given module name and data.
`encode_mssp`(values)	Encode an MSSP response with the supplied name/value pairs.
`encode_sb`(opt, payload)	Encode IAC SB <opt> <payload> IAC SE, doubling any 0xFF in payload.
`encode_ttype_send`()	Encode the server's request for the next TTYPE value.
`is_known_mud_client`(ttype_name)	Heuristic: does this TTYPE name look like a real MUD client?
`msp_music_marker`(name[, volume])
`msp_sound_marker`(name[, volume, priority])	Return an inline MSP sound marker for the given filename.
`parse_gmcp`(payload)	Inverse of encode_gmcp — returns the (module, data_or_None) tuple from a GMCP frame payload.
`parse_mtts_bitfield`(value)	Parse a third-stage MTTS response — the integer bitfield following the MTTS prefix.
`parse_ttype_is`(payload)	Parse the client's `IS <name>` TTYPE response.

Classes

`IacNegotiator`([on_ttype, on_gmcp, ...])	Per-session capability state and outbound command queue.
`IacParser`()	Byte-feed state machine for IAC sequences.