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package awa-mirage
SSH module given a flow
Parameters
module F : Mirage_flow.Smodule T : Mirage_time.Smodule M : Mirage_clock.MCLOCKSignature
module FLOW = Fpossible errors: incoming alert, processing failure, or a problem in the underlying flow.
The type for write errors.
we provide the FLOW interface
include Mirage_flow.S
with type error := error
and type write_error := write_error
val pp_write_error : write_error Fmt.tpp_write_error is the pretty-printer for write errors.
The type for flows. A flow represents the state of a single reliable stream that is connected to an endpoint.
read flow blocks until some data is available and returns a fresh buffer containing it.
The returned buffer will be of a size convenient to the flow implementation, but will always have at least 1 byte.
If the remote endpoint calls close then calls to read will keep returning data until all the in-flight data has been read. read flow will return `Eof when the remote endpoint has called close and when there is no more in-flight data.
val write : flow -> Cstruct.t -> (unit, write_error) result Lwt.twrite flow buffer writes a buffer to the flow. There is no indication when the buffer has actually been read and, therefore, it must not be reused. The contents may be transmitted in separate packets, depending on the underlying transport. The result Ok () indicates success, Error `Closed indicates that the connection is now closed and therefore the data could not be written. Other errors are possible.
val writev : flow -> Cstruct.t list -> (unit, write_error) result Lwt.twritev flow buffers writes a sequence of buffers to the flow. There is no indication when the buffers have actually been read and, therefore, they must not be reused. The result Ok () indicates success, Error `Closed indicates that the connection is now closed and therefore the data could not be written. Other errors are possible.
close flow flushes all pending writes and signals the remote endpoint that there will be no future writes. Once the remote endpoint has read all pending data, it is expected that calls to read on the remote return `Eof.
Note it is still possible for the remote endpoint to write to the flow and for the local endpoint to call read. This state where the local endpoint has called close but the remote endpoint has not called close is similar to that of a half-closed TCP connection or a Unix socket after shutdown(SHUTDOWN_WRITE).
close flow waits until the remote endpoint has also called close before returning. At this point no data can flow in either direction and resources associated with the flow can be freed.
val client_of_flow :
?authenticator:Awa.Keys.authenticator ->
user:string ->
[ `Pubkey of Awa.Hostkey.priv | `Password of string ] ->
Awa.Ssh.channel_request ->
FLOW.flow ->
(flow, error) result Lwt.tclient_of_flow ~authenticator ~user key channel_request flow upgrades the existing connection to SSH, mutually authenticates, opens a channel and sends the channel request.
type request = val spawn_server :
?stop:Lwt_switch.t ->
Awa.Server.t ->
Awa.Ssh.message list ->
F.flow ->
exec_callback ->
t Lwt.tspawn_server ?stop server msgs flow callback launches an internal SSH channels handler which can be stopped by stop. This SSH channels handler will call callback for every new channels requested by the client. msgs are the SSH hello given by Awa.Server.make which returns also a Awa.Server.t required here.
A basic usage of spawn_server is:
let ssh_channel_handler _cmd _ic _oc _ec =
Lwt.return_unit
let tcp_handler flow =
let server, msgs = Awa.Server.make private_key db in
SSH.spawn_server server msgs flow ssh_handler >>= fun _t ->
close flowNOTE: Even if the ssh_channel_handler is fulfilled, spawn_server continues to handle SSH channels. Only stop can really stop the internal SSH channels handler.
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