albatross/app/vmm_console.ml

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(* (c) 2017 Hannes Mehnert, all rights reserved *)
(* the process responsible for buffering console IO *)
(* communication channel is a single unix domain socket. The following commands
can be issued:
- Add name (by vmmd) --> creates a new console slurper for name,
and starts a read_console task
- Attach name --> attaches console of name: send existing stuff to client,
and record the requesting socket to receive further messages. A potential
earlier subscriber to the same console is closed. *)
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open Lwt.Infix
open Astring
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let my_version = `AV2
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let pp_unix_error ppf e = Fmt.string ppf (Unix.error_message e)
let active = ref String.Map.empty
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let read_console name ring channel () =
let id = Vmm_core.id_of_string name in
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Lwt.catch (fun () ->
let rec loop () =
Lwt_io.read_line channel >>= fun line ->
Logs.debug (fun m -> m "read %s" line) ;
let t = Ptime_clock.now () in
Vmm_ring.write ring (t, line) ;
(match String.Map.find name !active with
| None -> Lwt.return_unit
| Some fd ->
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let header = Vmm_asn.{ version = my_version ; sequence = 0L ; id } in
Vmm_lwt.write_wire fd (header, `Command (`Console_cmd (`Console_data (t, line)))) >>= function
| Error _ ->
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Vmm_lwt.safe_close fd >|= fun () ->
active := String.Map.remove name !active
| Ok () -> Lwt.return_unit) >>=
loop
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in
loop ())
(fun e ->
begin match e with
| Unix.Unix_error (e, f, _) ->
Logs.err (fun m -> m "%s error in %s: %a" name f pp_unix_error e)
| End_of_file ->
Logs.debug (fun m -> m "%s end of file while reading" name)
| exn ->
Logs.err (fun m -> m "%s error while reading %s" name (Printexc.to_string exn))
end ;
Lwt_io.close channel)
let open_fifo name =
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let fifo = Fpath.(Vmm_core.tmpdir / "fifo" / name) in
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Lwt.catch (fun () ->
Logs.debug (fun m -> m "opening %a for reading" Fpath.pp fifo) ;
Lwt_io.open_file ~mode:Lwt_io.Input (Fpath.to_string fifo) >>= fun channel ->
Lwt.return (Some channel))
(function
| Unix.Unix_error (e, f, _) ->
Logs.err (fun m -> m "%a error in %s: %a" Fpath.pp fifo f pp_unix_error e) ;
Lwt.return None
| exn ->
Logs.err (fun m -> m "%a error while reading %s" Fpath.pp fifo (Printexc.to_string exn)) ;
Lwt.return None)
let t = ref String.Map.empty
let add_fifo id =
let name = Vmm_core.string_of_id id in
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open_fifo name >|= function
| Some f ->
let ring = Vmm_ring.create () in
Logs.debug (fun m -> m "inserting %s" name) ;
let map = String.Map.add name ring !t in
t := map ;
Lwt.async (read_console name ring f) ;
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Ok "reading"
| None ->
Error (`Msg "opening")
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let subscribe s id =
let name = Vmm_core.string_of_id id in
Logs.debug (fun m -> m "attempting to attach %a" Vmm_core.pp_id id) ;
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match String.Map.find name !t with
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| None ->
active := String.Map.add name s !active ;
Lwt.return (Ok "waiing for VM")
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| Some r ->
let entries = Vmm_ring.read r in
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Logs.debug (fun m -> m "found %d history" (List.length entries)) ;
Lwt_list.iter_s (fun (i, v) ->
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let header = Vmm_asn.{ version = my_version ; sequence = 0L ; id } in
Vmm_lwt.write_wire s (header, `Command (`Console_cmd (`Console_data (i, v)))) >|= fun _ -> ())
entries >>= fun () ->
(match String.Map.find name !active with
| None -> Lwt.return_unit
| Some s -> Vmm_lwt.safe_close s) >|= fun () ->
active := String.Map.add name s !active ;
Ok "attached"
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let handle s addr () =
Logs.info (fun m -> m "handling connection %a" Vmm_lwt.pp_sockaddr addr) ;
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let rec loop () =
Vmm_lwt.read_wire s >>= function
| Error _ ->
Logs.err (fun m -> m "exception while reading") ;
Lwt.return_unit
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| Ok (header, `Command (`Console_cmd cmd)) ->
begin
(if not (Vmm_asn.version_eq header.Vmm_asn.version my_version) then
Lwt.return (Error (`Msg "ignoring data with bad version"))
else
match cmd with
| `Console_add -> add_fifo header.Vmm_asn.id
| `Console_subscribe -> subscribe s header.Vmm_asn.id
| `Console_data _ -> Lwt.return (Error (`Msg "unexpected command"))) >>= (function
| Ok msg -> Vmm_lwt.write_wire s (header, `Success (`String msg))
| Error (`Msg msg) ->
Logs.err (fun m -> m "error while processing command: %s" msg) ;
Vmm_lwt.write_wire s (header, `Failure msg)) >>= function
| Ok () -> loop ()
| Error _ ->
Logs.err (fun m -> m "exception while writing to socket") ;
Lwt.return_unit
end
| Ok wire ->
Logs.warn (fun m -> m "ignoring %a" Vmm_asn.pp_wire wire) ;
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loop ()
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in
loop () >>= fun () ->
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Vmm_lwt.safe_close s >|= fun () ->
Logs.warn (fun m -> m "disconnected")
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let jump _ file =
Sys.(set_signal sigpipe Signal_ignore) ;
Lwt_main.run
((Lwt_unix.file_exists file >>= function
| true -> Lwt_unix.unlink file
| false -> Lwt.return_unit) >>= fun () ->
let s = Lwt_unix.(socket PF_UNIX SOCK_STREAM 0) in
Lwt_unix.(bind s (ADDR_UNIX file)) >>= fun () ->
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Lwt_unix.listen s 1 ;
let rec loop () =
Lwt_unix.accept s >>= fun (cs, addr) ->
Lwt.async (handle cs addr) ;
loop ()
in
loop ())
let setup_log style_renderer level =
Fmt_tty.setup_std_outputs ?style_renderer ();
Logs.set_level level;
Logs.set_reporter (Logs_fmt.reporter ~dst:Format.std_formatter ())
open Cmdliner
let setup_log =
Term.(const setup_log
$ Fmt_cli.style_renderer ()
$ Logs_cli.level ())
let socket =
let doc = "Socket to listen on" in
let sock = Vmm_core.socket_path `Console in
Arg.(value & opt string sock & info [ "s" ; "socket" ] ~doc)
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let cmd =
Term.(ret (const jump $ setup_log $ socket)),
Term.info "vmm_console" ~version:"%%VERSION_NUM%%"
let () = match Term.eval cmd with `Ok () -> exit 0 | _ -> exit 1