Historical interest only: marketplace-2014 implementation of SSH.
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#lang racket/base
;;; Copyright 2010, 2011, 2012, 2013 Tony Garnock-Jones <tonyg@ccs.neu.edu>
;;; This file is part of marketplace-ssh.
;;; marketplace-ssh is free software: you can redistribute it and/or
;;; modify it under the terms of the GNU General Public License as
;;; published by the Free Software Foundation, either version 3 of the
;;; License, or (at your option) any later version.
;;; marketplace-ssh is distributed in the hope that it will be useful,
;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;; General Public License for more details.
;;; You should have received a copy of the GNU General Public License
;;; along with marketplace-ssh. If not, see
;;; <http://www.gnu.org/licenses/>.
(require racket/set)
(require racket/match)
(provide (struct-out ssh-channel)
(struct-out channel-name)
(struct-out channel-stream-name)
(struct-out channel-message)
(struct-out channel-stream-credit)
(struct-out channel-stream-data)
(struct-out channel-stream-extended-data)
(struct-out channel-stream-eof)
(struct-out channel-stream-notify)
(struct-out channel-stream-request)
(struct-out channel-stream-ok)
(struct-out channel-stream-fail)
(struct-out channel-stream-config)
(struct-out channel-stream-open-failure))
;; A CloseState is one of
;; - 'neither, indicating that neither side has signalled closure
;; - 'local, only the local end has signalled closure
;; - 'remote, only the remote end has signalled closure
;; - 'both, both ends have signalled closure.
;; Represents local knowledge of the state of a shared shutdown state
;; machine.
;; 'neither
;; / \
;; \/ \/
;; 'local 'remote
;; \ /
;; \/ \/
;; 'both
;; TODO: Once the presence-based routing table can be queried, the
;; CloseState becomes redundant, because we can just ask which roles
;; remain to decide whether either direction is still open.
;; A ChannelState is a (ssh-channel ...) TODO
;; Named ssh-channel to avoid conflicts with Racket's built-in
;; synchronous channels.
(struct ssh-channel (name ;; ChannelName
local-ref ;; Uint32
remote-ref ;; Maybe<Uint32>
outbound-packet-size ;; Maybe<Natural>
close-state ;; CloseState covering CLOSE signals
;; ChannelName = (channel-name Boolean Bytes Any)
;; Names a channel within a connection. Unique within a particular
;; connection. If (locally-originated?) is true, then the local peer
;; is the one that opened this channel, and the local peer is
;; reponsible for choosing the (identifier) and ensuring that it is
;; unique with respect to other locally-originated streams within this
;; connection; if false, the remote peer opened the channel, and the
;; (identifier) is chosen managed by the connection-control code. If
;; (locally-originated?) is true, the (type) is chosen by the local
;; peer, otherwise it is chosen by the remote peer.
(struct channel-name (locally-originated? type identifier) #:prefab)
;; ChannelStreamName = (channel-stream-name Boolean ChannelName)
;; Names a stream within a channel within a connection. If (inbound?)
;; is true, this is the stream of packets from the remote peer to the
;; local peer; if false, the reverse.
(struct channel-stream-name (inbound? channel) #:prefab)
;; ChannelMessage = (channel-message ChannelStreamName ChannelMessageBody)
;; Relates a message to a particular stream within a channel within a
;; connection.
(struct channel-message (stream-name body) #:prefab)
;; A ChannelMessageBody is one of
;; -- (channel-stream-credit NonNegativeInteger) **
;; Informs the publisher that it may transmit another (count)
;; bytes.
;; -- (channel-stream-data Bytes)
;; Data intended for the subscriber.
;; -- (channel-stream-extended-data Uint32 Bytes)
;; Extended data intended for the subscriber. The type code is one
;; of those defined in ssh-numbers.rkt; for example,
;; -- (channel-stream-eof)
;; Signals the end of the data stream. Notice that channel closure
;; is signalled with presence changes.
;; -- (channel-stream-notify Bytes Bytes)
;; One-way notification of SSH_MSG_CHANNEL_REQUEST.
;; -- (channel-stream-request Bytes Bytes)
;; -- (channel-stream-ok) **
;; -- (channel-stream-fail) **
;; -- (channel-stream-config Uint32 Bytes) **
;; SSH_MSG_CHANNEL_OPEN_CONFIRMATION, depending on direction of
;; travel. Must be sent before any channel-stream-credit messages.
;; -- (channel-stream-open-failure Uint32 Bytes)
;; Messages marked ** travel "upstream", from subscriber to publisher.
(struct channel-stream-credit (count) #:prefab)
(struct channel-stream-data (bytes) #:prefab)
(struct channel-stream-extended-data (type bytes) #:prefab)
(struct channel-stream-eof () #:prefab)
(struct channel-stream-notify (type bytes) #:prefab)
(struct channel-stream-request (type bytes) #:prefab)
(struct channel-stream-ok () #:prefab)
(struct channel-stream-fail () #:prefab)
(struct channel-stream-config (maximum-packet-size extra-data) #:prefab)
(struct channel-stream-open-failure (reason description) #:prefab)