mirage-types 2.8.0 · OCaml Package

TCP stack

A TCP stack that can send and receive reliable streams using the TCP protocol.

type buffer

The type for memory buffers.

type ip

The type for IPv4 stacks for this stack to connect to.

type ipaddr

The type for IP address representations.

type ipinput

The type for input function continuation to pass onto the underlying IP stack. This will normally be a NOOP for a conventional kernel, but a direct implementation will parse the buffer.

type flow

A flow represents the state of a single TCPv4 stream that is connected to an endpoint.

type error = [

| `Unknown of string
(*
an undiagnosed error.
*)
| `Timeout
(*
connection attempt did not get a valid response.
*)
| `Refused
(*
connection attempt was actively refused via an RST.
*)

]

The type for IO operation errors.

include DEVICE with type error := error and type id := ip

type +'a io

The type for potentially blocking I/O operation

type t

The type representing the internal state of the device

val disconnect : t -> unit io

Disconnect from the device. While this might take some time to complete, it can never result in an error.

include FLOW
  with type error := error
   and type 'a io := 'a io
   and type buffer := buffer
   and type flow := flow

val error_message : error -> string

Convert an error to a human-readable message, suitable for logging.

val read : flow -> [ `Ok of buffer | `Eof | `Error of error ] io

read flow will block until it either successfully reads a segment of data from the current flow, receives an Eof signifying that the connection is now closed, or an Error.

val write : flow -> buffer -> [ `Ok of unit | `Eof | `Error of error ] io

write flow buffer will block until buffer has been added to the send queue. 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, `Eof indicates that the connection is now closed and `Error indicates some other error.

val writev : flow -> buffer list -> [ `Ok of unit | `Eof | `Error of error ] io

writev flow buffers will block until the buffers have all been added to the send queue. There is no indication when the buffers have actually been read and, therefore, they must not be reused. The result `Ok () indicates success, `Eof indicates that the connection is now closed and `Error indicates some other error.

val close : flow -> unit io

close flow will flush all pending writes and signal 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 will 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).

The result unit io will become determined when the remote endpoint finishes calling write and calls close. At this point no data can flow in either direction and resources associated with the flow can be freed.

type callback = flow -> unit io

The type for application callback that receives a flow that it can read/write to.

val get_dest : flow -> ipaddr * int

Get the destination IPv4 address and destination port that a flow is currently connected to.

val write_nodelay : flow -> buffer -> unit io

write_nodelay flow will block until the contents of buffer list are all successfully transmitted to the remote endpoint. Buffering within the stack is minimized in this mode. Note that this API will change in a future revision to be a per-flow attribute instead of a separately exposed function.

val writev_nodelay : flow -> buffer list -> unit io

writev_nodelay flow will block until the contents of buffer list are all successfully transmitted to the remote endpoint. Buffering within the stack is minimized in this mode. Note that this API will change in a future revision to be a per-flow attribute instead of a separately exposed function.

val create_connection : 
  t ->
  (ipaddr * int) ->
  [ `Ok of flow | `Error of error ] io

create_connection t (addr,port) will open a TCPv4 connection to the specified endpoint.

val input : t -> listeners:(int -> callback option) -> ipinput

input t listeners defines a mapping of threads that are willing to accept new flows on a given port. If the callback returns None, the input function will return an RST to refuse connections on a port.

package mirage-types

TCP stack