miragesdk: re-org source code

Split the bits which can be re-used in other services (e.g. init dance
and the server-side of the control path). `main.ml` now only contains what
is specific to the DHCP logic (+ the /caf directory).

Signed-off-by: Thomas Gazagnaire <thomas@gazagnaire.org>

projects/miragesdk/dhcp-client/Makefile

@@ -1,5 +1,5 @@
 BASE=ocaml/opam:alpine-3.5_ocaml-4.04.0
-FILES=src/main.ml src/inflator.ml src/io_fs.ml src/bpf/dhcp.c \
+FILES=$(shell find src/ -regex '.*\.mli?') src/bpf/dhcp.c \
 	src/jbuild src/bpf/jbuild
 IMAGE=dhcp-client
 OBJS=obj/dhcp-client

projects/miragesdk/dhcp-client/calf/config.ml

@@ -33,9 +33,9 @@ let net =
   let key = Key.(create "input" Arg.(opt int 3 doc)) in
   netif_of_fd key
 
-let store =
+let ctl =
   let doc =
-    Key.Arg.info ~docv:"FD" ~doc:"Store interface" ["store"]
+    Key.Arg.info ~docv:"FD" ~doc:"Control interface" ["ctl"]
   in
   let key = Key.(create "output" Arg.(opt int 4 doc)) in
   netif_of_fd key
@@ -54,4 +54,4 @@ let main =
   foreign ~keys ~packages "Unikernel.Main"
     (time @-> network @-> network @-> job)
 
-let () = register "dhcp-client" [main $ default_time $ net $ store]
+let () = register "dhcp-client" [main $ default_time $ net $ ctl]

projects/miragesdk/dhcp-client/calf/unikernel.ml

@@ -199,13 +199,13 @@ end
 module Main
     (Time :Mirage_time_lwt.S)
     (Net  : Mirage_net_lwt.S)
-    (Store: Mirage_net_lwt.S) =
+    (Ctl  : Mirage_net_lwt.S) =
 struct
 
-  module API = API(Store)
+  module API = API(Ctl)
   module Dhcp_client = Dhcp_client_mirage.Make(Time)(Net)
 
-  let start () net store =
+  let start () net ctl =
     let requests = match Key_gen.codes () with
       | [] -> default_options
       | l  ->
@@ -220,6 +220,6 @@ struct
     Lwt_stream.last_new stream >>= fun result ->
     let result = of_ipv4_config result in
     Log.info (fun l -> l "found lease: %a" pp result);
-    API.set_ip store result.address
+    API.set_ip ctl result.address
 
 end

projects/miragesdk/dhcp-client/src/ctl.ml

@@ -0,0 +1,128 @@
+open Lwt.Infix
+
+let src = Logs.Src.create "init" ~doc:"Init steps"
+module Log = (val Logs.src_log src : Logs.LOG)
+
+(* FIXME: to avoid linking with gmp *)
+module IO = struct
+  type ic = unit
+  type oc = unit
+  type ctx = unit
+  let with_connection ?ctx:_ _uri ?init:_ _f = Lwt.fail_with "not allowed"
+  let read_all _ic = Lwt.fail_with "not allowed"
+  let read_exactly _ic _n = Lwt.fail_with "not allowed"
+  let write _oc _buf = Lwt.fail_with "not allowed"
+  let flush _oc = Lwt.fail_with "not allowed"
+  let ctx () = Lwt.return_none
+end
+
+(* FIXME: we don't use Irmin_unix.Git.FS.KV to avoid linking with gmp *)
+module Store = Irmin_git.FS.KV(IO)(Inflator)(Io_fs)
+module KV = Store(Irmin.Contents.String)
+
+let v path =
+  let config = Irmin_git.config path in
+  KV.Repo.v config >>= fun repo ->
+  KV.of_branch repo "calf"
+
+let set_listen_dir_hook () =
+  Irmin.Private.Watch.set_listen_dir_hook Irmin_watcher.hook
+
+module HTTP = struct
+
+  module Wm = struct
+    module Rd = Webmachine.Rd
+    include Webmachine.Make(Cohttp_lwt_unix.Server.IO)
+  end
+
+  let with_key rd f =
+    match KV.Key.of_string rd.Wm.Rd.dispatch_path with
+    | Ok x    -> f x
+    | Error _ -> Wm.respond 404 rd
+
+  let infof fmt =
+    Fmt.kstrf (fun msg () ->
+        let date = Int64.of_float (Unix.gettimeofday ()) in
+        Irmin.Info.v ~date ~author:"calf" msg
+      ) fmt
+
+  let ok = "{\"status\": \"ok\"}"
+
+  class item db = object(self)
+
+    inherit [Cohttp_lwt_body.t] Wm.resource
+
+    method private of_string rd =
+      Cohttp_lwt_body.to_string rd.Wm.Rd.req_body >>= fun value ->
+      with_key rd (fun key ->
+          let info = infof "Updating %a" KV.Key.pp key in
+          KV.set db ~info key value >>= fun () ->
+          let resp_body = `String ok in
+          let rd = { rd with Wm.Rd.resp_body } in
+          Wm.continue true rd
+        )
+
+    method private to_string rd =
+      with_key rd (fun key ->
+          KV.find db key >>= function
+          | Some value -> Wm.continue (`String value) rd
+          | None       -> assert false
+        )
+
+    method resource_exists rd =
+      with_key rd (fun key ->
+          KV.mem db key >>= fun mem ->
+          Wm.continue mem rd
+        )
+
+    method allowed_methods rd =
+      Wm.continue [`GET; `HEAD; `PUT; `DELETE] rd
+
+    method content_types_provided rd =
+      Wm.continue [
+        "plain", self#to_string
+      ] rd
+
+    method content_types_accepted rd =
+      Wm.continue [
+        "plain", self#of_string
+      ] rd
+
+    method delete_resource rd =
+      with_key rd (fun key ->
+          let info = infof "Deleting %a" KV.Key.pp key in
+          KV.remove db ~info key >>= fun () ->
+          let resp_body = `String ok in
+          Wm.continue true { rd with Wm.Rd.resp_body }
+        )
+  end
+
+  let v db routes =
+    let routes = List.map (fun r -> r, fun () -> new item db) routes in
+    let callback (_ch, _conn) request body =
+      let open Cohttp in
+      (Wm.dispatch' routes ~body ~request >|= function
+        | None        -> (`Not_found, Header.init (), `String "Not found", [])
+        | Some result -> result)
+      >>= fun (status, headers, body, path) ->
+      Log.info (fun l ->
+          l "%d - %s %s"
+            (Code.code_of_status status)
+            (Code.string_of_method (Request.meth request))
+            (Uri.path (Request.uri request)));
+      Log.debug (fun l -> l "path=%a" Fmt.(Dump.list string) path);
+      (* Finally, send the response to the client *)
+      Cohttp_lwt_unix.Server.respond ~flush:true ~headers ~body ~status ()
+    in
+    (* create the server and handle requests with the function defined above *)
+    let conn_closed (_, conn) =
+      Log.info (fun l ->
+          l "connection %s closed\n%!" (Cohttp.Connection.to_string conn))
+    in
+    Cohttp_lwt_unix.Server.make ~callback ~conn_closed ()
+end
+
+let serve ~routes db fd =
+  let http = HTTP.v db routes in
+  let on_exn e = Log.err (fun l -> l "ERROR: %a" Fmt.exn e) in
+  Cohttp_lwt_unix.Server.create ~on_exn ~mode:(`Fd fd) http

projects/miragesdk/dhcp-client/src/ctl.mli

@@ -0,0 +1,16 @@
+(** [Control] handle the server part of the control path, running in
+    the privileged container. *)
+
+module KV: Irmin.KV with type contents = string
+
+val v: string -> KV.t Lwt.t
+(** [v p] is the KV store storing the control state, located at path
+    [p] in the filesystem of the privileged container. *)
+
+val serve: routes:string list -> KV.t -> Lwt_unix.file_descr -> unit Lwt.t
+(** [serve ~routes kv fd] is the thread exposing the KV store [kv],
+    holding control state, running inside the privileged container.
+    [routes] are the routes exposed by the server (currently over a
+    simple HTTP server -- but will change to something else later,
+    probably protobuf) to the calf and [kv] is the control state
+    handler. *)

projects/miragesdk/dhcp-client/src/init.ml

@@ -0,0 +1,216 @@
+open Lwt.Infix
+
+let src = Logs.Src.create "init" ~doc:"Init steps"
+module Log = (val Logs.src_log src : Logs.LOG)
+
+let failf fmt = Fmt.kstrf Lwt.fail_with fmt
+
+module Fd = struct
+
+  type t = {
+    name: string;
+    fd  : Lwt_unix.file_descr;
+  }
+
+  let fd t = t.fd
+  let stdout = { name = "stdout"; fd = Lwt_unix.stdout }
+  let stderr = { name = "stderr"; fd = Lwt_unix.stderr }
+  let stdin  = { name = "stdin" ; fd = Lwt_unix.stdin  }
+
+  let to_int t =
+    (Obj.magic (Lwt_unix.unix_file_descr t.fd): int)
+
+  let pp ppf fd = Fmt.pf ppf "%s:%d" fd.name (to_int fd)
+
+  let close fd =
+    Log.debug (fun l -> l "close %a" pp fd);
+    Lwt_unix.close fd.fd
+
+  let dev_null =
+    Lwt_unix.of_unix_file_descr ~blocking:false
+      (Unix.openfile "/dev/null" [Unix.O_RDWR] 0)
+
+  let redirect_to_dev_null fd =
+    Log.debug (fun l -> l "redirect-stdin-to-dev-null");
+    Lwt_unix.close fd.fd >>= fun () ->
+    Lwt_unix.dup2 dev_null fd.fd;
+    Lwt_unix.close dev_null
+
+  let dup2 ~src ~dst =
+    Log.debug (fun l -> l "dup2 %a => %a" pp src pp dst);
+    Lwt_unix.dup2 src.fd dst.fd;
+    close src
+
+  let proxy_net ~net fd =
+    Log.debug (fun l -> l "proxy-net eth0 <=> %a" pp fd);
+    let rec listen_rawlink () =
+      Lwt_rawlink.read_packet net >>= fun buf ->
+      Log.debug (fun l -> l "PROXY-NET: => %a" Cstruct.hexdump_pp buf);
+      Log.debug (fun l -> l "PROXY-NET: => %S" (Cstruct.to_string buf));
+      let rec write buf =
+        Lwt_cstruct.write fd.fd buf >>= function
+        | 0 -> Lwt.return_unit
+        | n -> write (Cstruct.shift buf n)
+      in
+      write buf >>= fun () ->
+      listen_rawlink ()
+    in
+    let listen_socket () =
+      let len = 16 * 1024 in
+      let buf = Cstruct.create len in
+      let rec loop () =
+        Lwt_cstruct.read fd.fd buf >>= fun len ->
+        let buf = Cstruct.sub buf 0 len in
+        Log.debug (fun l -> l "PROXY-NET: <= %a" Cstruct.hexdump_pp buf);
+        Lwt_rawlink.send_packet net buf >>= fun () ->
+        loop ()
+      in
+      loop ()
+    in
+    Lwt.pick [
+      listen_rawlink ();
+      listen_socket ();
+    ]
+
+  let rec really_write dst buf off len =
+    match len with
+    | 0   -> Lwt.return_unit
+    | len ->
+      Lwt_unix.write dst.fd buf off len >>= fun n ->
+      really_write dst buf (off+n) (len-n)
+
+  let forward ~src ~dst =
+    Log.debug (fun l -> l "forward %a => %a" pp src pp dst);
+    let len = 16 * 1024 in
+    let buf = Bytes.create len in
+    let rec loop () =
+      Lwt_unix.read src.fd buf 0 len >>= fun len ->
+      if len = 0 then
+        (* FIXME: why this ever happen *)
+        Fmt.kstrf Lwt.fail_with "FORWARD[%a => %a]: EOF" pp src pp dst
+      else (
+        Log.debug (fun l ->
+            l "FORWARD[%a => %a]: %S (%d)"
+              pp src pp dst (Bytes.sub buf 0 len) len);
+        really_write dst buf 0 len >>= fun () ->
+        loop ()
+      )
+    in
+    loop ()
+
+  let proxy x y =
+    Lwt.pick [
+      forward ~src:x ~dst:y;
+      forward ~src:y ~dst:x;
+    ]
+
+end
+
+module Pipe = struct
+
+  type t = Fd.t * Fd.t
+
+  let priv = fst
+  let calf = snd
+
+  let socketpair name =
+    let priv, calf = Lwt_unix.(socketpair PF_UNIX SOCK_STREAM 0) in
+    Lwt_unix.clear_close_on_exec priv;
+    Lwt_unix.clear_close_on_exec calf;
+    { Fd.name = name; fd = priv }, { Fd.name = name ^ "-calf"; fd = calf }
+
+  let pipe name =
+    let priv, calf = Lwt_unix.pipe () in
+    Lwt_unix.clear_close_on_exec priv;
+    Lwt_unix.clear_close_on_exec calf;
+    { Fd.name = name; fd = priv }, { Fd.name = name ^ "-calf"; fd = calf }
+
+  (* logs pipe *)
+  let stdout = pipe "logs-out"
+  let stderr = pipe "logs-err"
+
+  (* store pipe *)
+  let ctl = socketpair "ctl"
+
+  (* network pipe *)
+  let net = socketpair "net"
+
+  (* metrics pipe *)
+  let metrics = pipe "metrics"
+
+end
+
+let exec_calf cmd =
+  Fd.(redirect_to_dev_null stdin) >>= fun () ->
+
+  (* close parent fds *)
+  Fd.close Pipe.(priv stdout)  >>= fun () ->
+  Fd.close Pipe.(priv stderr)  >>= fun () ->
+  Fd.close Pipe.(priv ctl)     >>= fun () ->
+  Fd.close Pipe.(priv net)     >>= fun () ->
+  Fd.close Pipe.(priv metrics) >>= fun () ->
+
+  let cmds = String.concat " " cmd in
+
+  let calf_net = Pipe.(calf net) in
+  let calf_ctl = Pipe.(calf ctl) in
+  let calf_stdout = Pipe.(calf stdout) in
+  let calf_stderr = Pipe.(calf stderr) in
+
+  Log.info (fun l -> l "Executing %s" cmds);
+  Log.debug (fun l -> l "net-fd=%a store-fd=%a" Fd.pp calf_net Fd.pp calf_ctl);
+
+  Fd.dup2 ~src:calf_stdout ~dst:Fd.stdout >>= fun () ->
+  Fd.dup2 ~src:calf_stderr ~dst:Fd.stderr >>= fun () ->
+
+  (* exec the calf *)
+  Unix.execve (List.hd cmd) (Array.of_list cmd) [||]
+
+let rawlink ?filter ethif =
+  Log.debug (fun l -> l "bringing up %s" ethif);
+  (try Tuntap.set_up_and_running ethif
+   with e -> Log.err (fun l -> l "rawlink: %a" Fmt.exn e));
+  Lwt_rawlink.open_link ?filter ethif
+
+let check_exit_status cmd status =
+  let cmds = String.concat " " cmd in
+  match status with
+  | Unix.WEXITED 0   -> Lwt.return_unit
+  | Unix.WEXITED i   -> failf "%s: exit %d" cmds i
+  | Unix.WSIGNALED i -> failf "%s: signal %d" cmds i
+  | Unix.WSTOPPED i  -> failf "%s: stopped %d" cmds i
+
+let exec_priv ~pid ~cmd ~net ~ctl ~handlers =
+
+  (* close child fds *)
+  Fd.(redirect_to_dev_null stdin)   >>= fun () ->
+  Fd.close Pipe.(calf stdout)  >>= fun () ->
+  Fd.close Pipe.(calf stderr)  >>= fun () ->
+  Fd.close Pipe.(calf net)     >>= fun () ->
+  Fd.close Pipe.(calf ctl)     >>= fun () ->
+  Fd.close Pipe.(calf metrics) >>= fun () ->
+
+  let wait () =
+    Lwt_unix.waitpid [] pid >>= fun (_pid, w) ->
+    Lwt_io.flush_all () >>= fun () ->
+
+    check_exit_status cmd w
+  in
+  Lwt.pick ([
+      wait ();
+      (* data *)
+      Fd.proxy_net ~net Pipe.(priv net);
+
+      (* redirect the calf stdout to the shim stdout *)
+      Fd.forward ~src:Pipe.(priv stdout)  ~dst:Fd.stdout;
+      Fd.forward ~src:Pipe.(priv stderr)  ~dst:Fd.stderr;
+      (* TODO: Init.Fd.forward ~src:Init.Pipe.(priv metrics) ~dst:Init.Fd.metric; *)
+      ctl ();
+      handlers ();
+    ])
+
+let run ~net ~ctl ~handlers cmd =
+  Lwt_io.flush_all () >>= fun () ->
+  match Lwt_unix.fork () with
+  | 0   -> exec_calf cmd
+  | pid -> exec_priv ~pid ~cmd ~net ~ctl ~handlers

projects/miragesdk/dhcp-client/src/init.mli

@@ -0,0 +1,109 @@
+(** Init functions.
+
+    [Init] contains funcitons to initialise the state of the
+    privileged container.
+
+    {ul
+
+    {- fowrard and filter the network traffic using BPF (for instance
+       to allow only DHCP traffic).}
+    {- open pipes for forwarding the calf's stdout and stderr
+       to the privileged container's ones.}
+    {- open a pipe to forward the metrics.}
+    {- open a socket pair with the calf to be able to transmit control
+       data, e.g. the IP address once a DHCP lease is obtained.}
+    }*)
+
+
+module Fd: sig
+
+  type t
+  (** The type for file descriptors. *)
+
+  val pp: t Fmt.t
+  (** [pp_fd] pretty prints a file descriptor. *)
+
+  val fd: t -> Lwt_unix.file_descr
+  (** [fd t] is [t]'s underlying unix file descriptor. *)
+
+  val to_int: t -> int
+(** [to_int fd] is [fd]'s number. *)
+
+  val redirect_to_dev_null: t -> unit Lwt.t
+  (** [redirect_to_dev_null fd] redirects [fd] [/dev/null]. *)
+
+  val close: t -> unit Lwt.t
+  (** [close fd] closes [fd]. *)
+
+  val dup2: src:t -> dst:t -> unit Lwt.t
+  (** [dup2 ~src ~dst] calls [Unix.dup2] on [src] and [dst]. *)
+
+  val proxy_net: net:Lwt_rawlink.t -> t -> unit Lwt.t
+  (** [proxy_net ~net fd] proxies the traffic between the raw net link
+      [net] and [fd]. *)
+
+  val forward: src:t -> dst:t -> unit Lwt.t
+  (** [forward ~src ~dst] forwards the flow from [src] to [dst]. *)
+
+  (** {1 Usefull File Descriptors} *)
+
+  val stdin: t
+  (** [stdin] is the standart input. *)
+
+  val stdout: t
+  (** [stdout] is the standard output. *)
+
+  val stderr: t
+  (** [stderr] is the standard error. *)
+
+end
+
+module Pipe: sig
+
+  type t
+  (** The type for pipes. Could be either uni-directional (normal
+      pipes) or a bi-directional (socket pairs). *)
+
+  val priv: t -> Fd.t
+  (** [priv p] is the private side of the pipe [p]. *)
+
+  val calf: t -> Fd.t
+  (** [calf p] is the calf side of the pipe [p]. *)
+
+  (** {1 Useful Pipes} *)
+
+  val stdout: t
+  (** [stdout] is the uni-directional pipe from the calf's stdout . *)
+
+  val stderr: t
+  (** [stderr] is the uni-directional pipe from the calf's stderr. *)
+
+  val metrics: t
+  (** [metrics] is the uni-directional pipe fomr the calf's metric
+      endpoint. *)
+
+  val ctl: t
+  (** [ctl] is the bi-directional pipe used to exchange control
+      data between the calf and the priv containers. *)
+
+  val net: t
+  (** [net] is the bi-directional pipe used to exchange network
+      traffic between the calf and the priv containers. *)
+
+end
+
+val rawlink: ?filter:string -> string -> Lwt_rawlink.t
+(** [rawlink ?filter i] is the net raw link to the interface [i] using
+    the (optional) BPF filter [filter]. *)
+
+val run:
+  net:Lwt_rawlink.t ->
+  ctl:(unit -> unit Lwt.t) ->
+  handlers:(unit -> unit Lwt.t) ->
+  string list -> unit Lwt.t
+(** [run ~net ~ctl ~handlers cmd] runs [cmd] in a unprivileged calf
+    process. [ctl] is the control thread connected to the {Pipe.ctl}
+    pipe. [net] is the net raw link which will be connected to the
+    calf via the {!Pipe.net} socket pair. [handlers] are the system
+    handler thread which will react to control data to perform
+    privileged system actions. *)

projects/miragesdk/dhcp-client/src/main.ml

@@ -5,288 +5,6 @@ module Log = (val Logs.src_log src : Logs.LOG)
 
 let failf fmt = Fmt.kstrf Lwt.fail_with fmt
 
-type fd = {
-  name: string;
-  fd  : Lwt_unix.file_descr;
-}
-
-let stdout = { name = "stdout"; fd = Lwt_unix.stdout }
-let stderr = { name = "stderr"; fd = Lwt_unix.stderr }
-let stdin  = { name = "stdin" ; fd = Lwt_unix.stdin  }
-
-let int_of_fd (fd:Lwt_unix.file_descr) =
-  (Obj.magic (Lwt_unix.unix_file_descr fd): int)
-
-let pp_fd ppf fd = Fmt.pf ppf "%s:%d" fd.name (int_of_fd fd.fd)
-
-let close fd =
-  Log.debug (fun l -> l "close %a" pp_fd fd);
-  Lwt_unix.close fd.fd
-
-let dev_null =
-  Lwt_unix.of_unix_file_descr ~blocking:false
-    (Unix.openfile "/dev/null" [Unix.O_RDWR] 0)
-
-let close_and_dup fd =
-  Log.debug (fun l -> l "close-and-dup %a" pp_fd fd);
-  Lwt_unix.close fd.fd >>= fun () ->
-  Lwt_unix.dup2 dev_null fd.fd;
-  Lwt_unix.close dev_null
-
-let dup2 ~src ~dst =
-  Log.debug (fun l -> l "dup2 %a => %a" pp_fd src pp_fd dst);
-  Lwt_unix.dup2 src.fd dst.fd;
-  close src
-
-let proxy_rawlink ~rawlink ~fd =
-  Log.debug (fun l -> l "proxy-netif eth0 <=> %a" pp_fd fd);
-  let rec listen_rawlink () =
-    Lwt_rawlink.read_packet rawlink >>= fun buf ->
-    Log.debug (fun l -> l "PROXY-NETIF: => %a" Cstruct.hexdump_pp buf);
-    Log.debug (fun l -> l "PROXY-NETIF: => %S" (Cstruct.to_string buf));
-    let rec write buf =
-      Lwt_cstruct.write fd.fd buf >>= function
-      | 0 -> Lwt.return_unit
-      | n -> write (Cstruct.shift buf n)
-    in
-    write buf >>= fun () ->
-    listen_rawlink ()
-  in
-  let listen_socket () =
-    let len = 16 * 1024 in
-    let buf = Cstruct.create len in
-    let rec loop () =
-      Lwt_cstruct.read fd.fd buf >>= fun len ->
-      let buf = Cstruct.sub buf 0 len in
-      Log.debug (fun l -> l "PROXY-NETIF: <= %a" Cstruct.hexdump_pp buf);
-      Lwt_rawlink.send_packet rawlink buf >>= fun () ->
-      loop ()
-    in
-    loop ()
-  in
-  Lwt.pick [
-    listen_rawlink ();
-    listen_socket ();
-  ]
-
-let rec really_write dst buf off len =
-  match len with
-  | 0   -> Lwt.return_unit
-  | len ->
-    Lwt_unix.write dst.fd buf off len >>= fun n ->
-    really_write dst buf (off+n) (len-n)
-
-let forward ~src ~dst =
-  Log.debug (fun l -> l "forward %a => %a" pp_fd src pp_fd dst);
-  let len = 16 * 1024 in
-  let buf = Bytes.create len in
-  let rec loop () =
-    Lwt_unix.read src.fd buf 0 len >>= fun len ->
-    if len = 0 then
-      (* FIXME: why this ever happen *)
-      Fmt.kstrf Lwt.fail_with "FORWARD[%a => %a]: EOF" pp_fd src pp_fd dst
-    else (
-      Log.debug (fun l ->
-          l "FORWARD[%a => %a]: %S (%d)"
-            pp_fd src pp_fd dst (Bytes.sub buf 0 len) len);
-      really_write dst buf 0 len >>= fun () ->
-      loop ()
-    )
-  in
-  loop ()
-
-let proxy x y =
-  Lwt.pick [
-    forward ~src:x ~dst:y;
-    forward ~src:y ~dst:x;
-  ]
-
-(* Prepare the fd space before we fork to run the calf *)
-
-let socketpair name =
-  let priv, calf = Lwt_unix.(socketpair PF_UNIX SOCK_STREAM 0) in
-  Lwt_unix.clear_close_on_exec priv;
-  Lwt_unix.clear_close_on_exec calf;
-  { name = name; fd = priv }, { name = name ^ "-calf"; fd = calf }
-
-let pipe name =
-  let priv, calf = Lwt_unix.pipe () in
-  Lwt_unix.clear_close_on_exec priv;
-  Lwt_unix.clear_close_on_exec calf;
-  { name = name; fd = priv }, { name = name ^ "-calf"; fd = calf }
-
-(* logs pipe *)
-let logs_out = pipe "logs-out"
-let logs_err = pipe "logs-err"
-
-(* store pipe *)
-let store = socketpair "store"
-
-(* network pipe *)
-let net = socketpair "net"
-
-(* metrics pipe *)
-(* let metrics = make "metrics" *)
-
-let child cmd =
-  close_and_dup stdin  >>= fun () ->
-
-  (* close parent fds *)
-  close (fst logs_out) >>= fun () ->
-  close (fst logs_err) >>= fun () ->
-  close (fst store)    >>= fun () ->
-  close (fst net)      >>= fun () ->
-  (*
-    close (fst metrics) >>= fun () ->
-  *)
-
-  let cmds = String.concat " " cmd in
-  Log.info (fun l -> l "Executing %s" cmds);
-  Log.debug (fun l ->
-      l "net-fd=%a store-fd=%a" pp_fd (snd net) pp_fd (snd store));
-
-  dup2 ~src:(snd logs_out) ~dst:stdout >>= fun () ->
-  dup2 ~src:(snd logs_err) ~dst:stderr >>= fun () ->
-
-  (* exec the calf *)
-  Unix.execve (List.hd cmd) (Array.of_list cmd) [||]
-
-module Store = struct
-
-  (* FIXME: to avoid linking with gmp *)
-  module IO = struct
-    type ic = unit
-    type oc = unit
-    type ctx = unit
-    let with_connection ?ctx:_ _uri ?init:_ _f = Lwt.fail_with "not allowed"
-    let read_all _ic = Lwt.fail_with "not allowed"
-    let read_exactly _ic _n = Lwt.fail_with "not allowed"
-    let write _oc _buf = Lwt.fail_with "not allowed"
-    let flush _oc = Lwt.fail_with "not allowed"
-    let ctx () = Lwt.return_none
-  end
-
-  (* FIXME: we don't use Irmin_unix.Git.FS.KV to avoid linking with gmp *)
-  module Store = Irmin_git.FS.KV(IO)(Inflator)(Io_fs)
-  module KV = Store(Irmin.Contents.String)
-
-  let client () =
-    let config = Irmin_git.config "/data" in
-    KV.Repo.v config >>= fun repo ->
-    KV.of_branch repo "calf"
-
-  let set_listen_dir_hook () =
-    Irmin.Private.Watch.set_listen_dir_hook Irmin_watcher.hook
-
-  module HTTP = struct
-
-    module Wm = struct
-      module Rd = Webmachine.Rd
-      include Webmachine.Make(Cohttp_lwt_unix.Server.IO)
-    end
-
-    let with_key rd f =
-      match KV.Key.of_string rd.Wm.Rd.dispatch_path with
-      | Ok x    -> f x
-      | Error _ -> Wm.respond 404 rd
-
-    let infof fmt =
-      Fmt.kstrf (fun msg () ->
-          let date = Int64.of_float (Unix.gettimeofday ()) in
-          Irmin.Info.v ~date ~author:"calf" msg
-        ) fmt
-
-    let ok = "{\"status\": \"ok\"}"
-
-    class item db = object(self)
-
-      inherit [Cohttp_lwt_body.t] Wm.resource
-
-      method private of_string rd =
-        Cohttp_lwt_body.to_string rd.Wm.Rd.req_body >>= fun value ->
-        with_key rd (fun key ->
-            let info = infof "Updating %a" KV.Key.pp key in
-            KV.set db ~info key value >>= fun () ->
-            let resp_body = `String ok in
-            let rd = { rd with Wm.Rd.resp_body } in
-            Wm.continue true rd
-          )
-
-      method private to_string rd =
-        with_key rd (fun key ->
-            KV.find db key >>= function
-            | Some value -> Wm.continue (`String value) rd
-            | None       -> assert false
-          )
-
-      method resource_exists rd =
-        with_key rd (fun key ->
-            KV.mem db key >>= fun mem ->
-            Wm.continue mem rd
-          )
-
-      method allowed_methods rd =
-        Wm.continue [`GET; `HEAD; `PUT; `DELETE] rd
-
-      method content_types_provided rd =
-        Wm.continue [
-          "plain", self#to_string
-        ] rd
-
-      method content_types_accepted rd =
-        Wm.continue [
-          "plain", self#of_string
-        ] rd
-
-      method delete_resource rd =
-        with_key rd (fun key ->
-            let info = infof "Deleting %a" KV.Key.pp key in
-            KV.remove db ~info key >>= fun () ->
-            let resp_body = `String ok in
-            Wm.continue true { rd with Wm.Rd.resp_body }
-          )
-    end
-
-    let v db =
-      let routes = [
-        ("/ip"          , fun () -> new item db);
-        ("/domain"      , fun () -> new item db);
-        ("/search"      , fun () -> new item db);
-        ("/mtu"         , fun () -> new item db);
-        ("/nameserver/*", fun () -> new item db);
-      ] in
-      let callback (_ch, _conn) request body =
-        let open Cohttp in
-        (Wm.dispatch' routes ~body ~request >|= function
-          | None        -> (`Not_found, Header.init (), `String "Not found", [])
-          | Some result -> result)
-        >>= fun (status, headers, body, path) ->
-        Log.info (fun l ->
-            l "%d - %s %s"
-              (Code.code_of_status status)
-              (Code.string_of_method (Request.meth request))
-              (Uri.path (Request.uri request)));
-        Log.debug (fun l -> l "path=%a" Fmt.(Dump.list string) path);
-        (* Finally, send the response to the client *)
-        Cohttp_lwt_unix.Server.respond ~flush:true ~headers ~body ~status ()
-      in
-      (* create the server and handle requests with the function defined above *)
-      let conn_closed (_, conn) =
-        Log.info (fun l ->
-            l "connection %s closed\n%!" (Cohttp.Connection.to_string conn))
-      in
-      Cohttp_lwt_unix.Server.make ~callback ~conn_closed ()
-    end
-
-  let serve () =
-    client () >>= fun db ->
-    let http = HTTP.v db in
-    let fd = fst store in
-    let on_exn e = Log.err (fun l -> l "XXX %a" Fmt.exn e) in
-    Log.info (fun l -> l "serving KV store on %a" pp_fd fd);
-    Cohttp_lwt_unix.Server.create ~on_exn ~mode:(`Fd fd.fd) http
-
-end
 
 module Handlers = struct
 
@@ -298,7 +16,7 @@ module Handlers = struct
     | _ -> None
 
   let ip t =
-    Store.KV.watch_key t ["ip"] (fun diff ->
+    Ctl.KV.watch_key t ["ip"] (fun diff ->
         match contents_of_diff diff with
         | Some ip ->
           Log.info (fun l -> l "SET IP to %s" ip);
@@ -311,8 +29,8 @@ module Handlers = struct
     ip;
   ]
 
-  let install () =
-    Store.client () >>= fun db ->
+  let watch path =
+    Ctl.v path >>= fun db ->
     Lwt_list.map_p (fun f -> f db) handlers >>= fun _ ->
     let t, _ = Lwt.task () in
     t
@@ -321,59 +39,21 @@ end
 
 external bpf_filter: unit -> string = "bpf_filter"
 
-let rawlink ethif =
-  Log.debug (fun l -> l "bringing up %s" ethif);
-  (try Tuntap.set_up_and_running ethif
-   with e -> Log.err (fun l -> l "rawling: %a" Fmt.exn e));
-  Lwt_rawlink.open_link ~filter:(bpf_filter ()) ethif
-
-let check_exit_status cmd status =
-  let cmds = String.concat " " cmd in
-  match status with
-  | Unix.WEXITED 0   -> Lwt.return_unit
-  | Unix.WEXITED i   -> failf "%s: exit %d" cmds i
-  | Unix.WSIGNALED i -> failf "%s: signal %d" cmds i
-  | Unix.WSTOPPED i  -> failf "%s: stopped %d" cmds i
-
-let parent cmd pid ethif =
-  (* network traffic *)
-  let rawlink = rawlink ethif in
-
-  (* close child fds *)
-  close_and_dup stdin  >>= fun () ->
-  close (snd logs_out) >>= fun () ->
-  close (snd logs_err) >>= fun () ->
-  close (snd net)      >>= fun () ->
-  close (snd store)    >>= fun () ->
-  (*
-  close (snd metrics) >>= fun () ->
-  *)
-  let wait () =
-    Lwt_unix.waitpid [] pid >>= fun (_pid, w) ->
-    Lwt_io.flush_all () >>= fun () ->
-
-    check_exit_status cmd w
-  in
-  Lwt.pick [
-    wait ();
-    (* data *)
-    proxy_rawlink ~rawlink ~fd:(fst net);
-
-    (* redirect the calf stdout to the shim stdout *)
-    forward ~src:(fst logs_out) ~dst:stdout;
-    forward ~src:(fst logs_err) ~dst:stderr;
-    (* metrics: TODO *)
-
-    Store.serve ();
-    Handlers.install ();
-  ]
-
-let run () cmd ethif =
+let run () cmd ethif path =
   Lwt_main.run (
-    Lwt_io.flush_all () >>= fun () ->
-    match Lwt_unix.fork () with
-    | 0   -> child cmd
-    | pid -> parent cmd pid ethif
+    let net = Init.rawlink ~filter:(bpf_filter ()) ethif in
+    let routes = [
+      "/ip";
+      "/domain";
+      "/search";
+      "/mtu";
+      "/nameservers/*"
+    ] in
+    Ctl.v "/data" >>= fun ctl ->
+    let fd = Init.(Fd.fd @@ Pipe.(priv ctl)) in
+    let ctl () = Ctl.serve ~routes ctl fd in
+    let handlers () = Handlers.watch path in
+    Init.run ~net ~ctl ~handlers cmd
   )
 
 (* CLI *)
@@ -392,6 +72,9 @@ let setup_log style_renderer level =
 let setup_log =
   Term.(const setup_log $ Fmt_cli.style_renderer () $ Logs_cli.level ())
 
+let ctl = string_of_int Init.(Fd.to_int Pipe.(calf ctl))
+let net = string_of_int Init.(Fd.to_int Pipe.(calf net))
+
 let cmd =
   (* FIXME: use runc isolation
    let default_cmd = [
@@ -401,7 +84,7 @@ let cmd =
   ] in
   *)
   let default_cmd = [
-    "/dhcp-client-calf"; "--store=10"; "--net=12"
+    "/dhcp-client-calf"; "--ctl="^ctl; "--net="^net
   ] in
   let doc =
     Arg.info ~docv:"CMD" ~doc:"Command to run the calf process." ["cmd"]
@@ -421,18 +104,3 @@ let run =
 let () = match Term.eval run with
   | `Error _ -> exit 1
   | _        -> exit 0
-
-(*
-
-let kv_store = Unix.pipe ()
-
-let install_logger () =
-  Logs_syslog_lwt.udp_reporter (Unix.inet_addr_of_string "127.0.0.1") ()
-  >|= fun r ->
-  Logs.set_reporter r
-
-let () = Lwt_main.run (
-    install_logger () >>= fun () ->
-    fd_of_tap0 >>= fun fd ->
-  )
-*)

projects/miragesdk/examples/mirage-dhcp.yml

@@ -19,7 +19,7 @@ system:
     command: [/usr/bin/binfmt, -dir, /etc/binfmt.d/, -mount, /binfmt_misc]
   - name: dhcp-client
     network_mode: host
-    image: "mobylinux/dhcp-client:d910ad5712a86cf2848753eecd1b7d07d80ad095"
+    image: "mobylinux/dhcp-client:f6ef2cc4c3bf7dcad643f22fbd3d355af1725105"
     capabilities:
      - CAP_NET_ADMIN # to bring eth0 up
      - CAP_NET_RAW   # to read /dev/eth0