116 lines
4.6 KiB
Racket
116 lines
4.6 KiB
Racket
#lang racket/base
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(require racket/set)
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(require racket/match)
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(provide (struct-out ssh-channel)
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(struct-out channel-name)
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(struct-out channel-stream-name)
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(struct-out channel-message)
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(struct-out channel-stream-credit)
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(struct-out channel-stream-data)
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(struct-out channel-stream-extended-data)
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(struct-out channel-stream-eof)
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(struct-out channel-stream-notify)
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(struct-out channel-stream-request)
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(struct-out channel-stream-ok)
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(struct-out channel-stream-fail)
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(struct-out channel-stream-config)
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(struct-out channel-stream-open-failure))
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;; A CloseState is one of
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;; - 'neither, indicating that neither side has signalled closure
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;; - 'local, only the local end has signalled closure
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;; - 'remote, only the remote end has signalled closure
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;; - 'both, both ends have signalled closure.
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;; Represents local knowledge of the state of a shared shutdown state
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;; machine.
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;;
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;; 'neither
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;; / \
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;; \/ \/
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;; 'local 'remote
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;; \ /
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;; \/ \/
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;; 'both
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;; TODO: Once the presence-based routing table can be queried, the
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;; CloseState becomes redundant, because we can just ask which roles
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;; remain to decide whether either direction is still open.
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;; A ChannelState is a (ssh-channel ...) TODO
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;; Named ssh-channel to avoid conflicts with Racket's built-in
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;; synchronous channels.
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(struct ssh-channel (name ;; ChannelName
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local-ref ;; Uint32
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remote-ref ;; Maybe<Uint32>
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outbound-packet-size ;; Maybe<Natural>
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close-state ;; CloseState covering CLOSE signals
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)
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#:transparent)
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;; ChannelName = (channel-name Boolean Bytes Any)
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;; Names a channel within a connection. Unique within a particular
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;; connection. If (locally-originated?) is true, then the local peer
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;; is the one that opened this channel, and the local peer is
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;; reponsible for choosing the (identifier) and ensuring that it is
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;; unique with respect to other locally-originated streams within this
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;; connection; if false, the remote peer opened the channel, and the
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;; (identifier) is chosen managed by the connection-control code. If
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;; (locally-originated?) is true, the (type) is chosen by the local
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;; peer, otherwise it is chosen by the remote peer.
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(struct channel-name (locally-originated? type identifier) #:prefab)
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;; ChannelStreamName = (channel-stream-name Boolean ChannelName)
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;; Names a stream within a channel within a connection. If (inbound?)
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;; is true, this is the stream of packets from the remote peer to the
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;; local peer; if false, the reverse.
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(struct channel-stream-name (inbound? channel) #:prefab)
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;; ChannelMessage = (channel-message ChannelStreamName ChannelMessageBody)
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;; Relates a message to a particular stream within a channel within a
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;; connection.
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(struct channel-message (stream-name body) #:prefab)
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;; A ChannelMessageBody is one of
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;; -- (channel-stream-credit NonNegativeInteger) **
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;; Informs the publisher that it may transmit another (count)
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;; bytes.
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;; -- (channel-stream-data Bytes)
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;; Data intended for the subscriber.
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;; -- (channel-stream-extended-data Uint32 Bytes)
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;; Extended data intended for the subscriber. The type code is one
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;; of those defined in ssh-numbers.rkt; for example,
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;; SSH_EXTENDED_DATA_STDERR.
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;; -- (channel-stream-eof)
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;; Signals the end of the data stream. Notice that channel closure
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;; is signalled with presence changes.
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;; -- (channel-stream-notify Bytes Bytes)
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;; One-way notification of SSH_MSG_CHANNEL_REQUEST.
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;; -- (channel-stream-request Bytes Bytes)
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;; RPC SSH_MSG_CHANNEL_REQUEST request.
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;; -- (channel-stream-ok) **
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;; RPC SSH_MSG_CHANNEL_REQUEST reply.
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;; -- (channel-stream-fail) **
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;; RPC SSH_MSG_CHANNEL_REQUEST error.
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;; -- (channel-stream-config Uint32 Bytes) **
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;; Either SSH_MSG_CHANNEL_OPEN or
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;; SSH_MSG_CHANNEL_OPEN_CONFIRMATION, depending on direction of
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;; travel. Must be sent before any channel-stream-credit messages.
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;; -- (channel-stream-open-failure Uint32 Bytes)
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;; SSH_MSG_CHANNEL_OPEN_FAILURE.
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;;
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;; Messages marked ** travel "upstream", from subscriber to publisher.
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(struct channel-stream-credit (count) #:prefab)
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(struct channel-stream-data (bytes) #:prefab)
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(struct channel-stream-extended-data (type bytes) #:prefab)
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(struct channel-stream-eof () #:prefab)
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(struct channel-stream-notify (type bytes) #:prefab)
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(struct channel-stream-request (type bytes) #:prefab)
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(struct channel-stream-ok () #:prefab)
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(struct channel-stream-fail () #:prefab)
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(struct channel-stream-config (maximum-packet-size extra-data) #:prefab)
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(struct channel-stream-open-failure (reason description) #:prefab)
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