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opam-version: "2.0"
name: "mirage-vnetif"
maintainer: "Magnus Skjegstad <>"
authors: "Magnus Skjegstad <>"
homepage: ""
bug-reports: ""
dev-repo: "git+"
doc: ""
license: "ISC"
build: [
["jbuilder" "subst" "-p" name] {pinned}
["jbuilder" "build" "-p" name "-j" jobs]
depends: [
"ocaml" {>= "4.04.2"}
"jbuilder" {build & >="1.0+beta7"}
"mirage-time-lwt" {>= "1.0.0"}
"mirage-clock-lwt" {>= "1.2.0"}
"mirage-net-lwt" {>= "1.0.0"}
"cstruct" {>="2.4.0"}
"ipaddr" {>= "3.0.0"}
tags: ["org:mirage"]
synopsis: "Virtual network interface and software switch for Mirage"
description: """\
Provides the module `Vnetif` which can be used as a replacement for the regular `Netif` implementation in Xen and Unix. Stacks built using `Vnetif` are connected to a software switch that allows the stacks to communicate as if they were connected to the same LAN.
An example of a unikernel that communicates with itself over `Vnetif` can be seen [here]( An iperf-like performance test is available [here]( The examples can be compiled for Unix and Xen and do not need access to a real network interface.
## Install
opam install mirage-vnetif
## Getting started
First, construct a TCP/IP stack based on `vnetif`:
module S = struct
module B = Basic_backend.Make
module V = Vnetif.Make(B)
module E = Ethif.Make(V)
module I = Ipv4.Make(E)(Clock)(OS.Time)
module U = Udp.Make(I)
module T = Tcp.Flow.Make(I)(OS.Time)(Clock)(Random)
module S = Tcpip_stack_direct.Make(C)(OS.Time)(Random)(V)(E)(I)(U)(T)
include S
Since we don't have the mirage-tool to help us we have to construct the stack manually. This code would usually be generated in `` by `mirage configure --xen/unix`.
let or_error name fn t =
fn t
>>= function
| `Error e -> fail (Failure ("Error starting " ^ name))
| `Ok t -> return t
let create_stack c backend ip netmask gw =
or_error "backend" S.V.connect backend >>= fun netif ->
or_error "ethif" S.E.connect netif >>= fun ethif ->
or_error "ipv4" S.I.connect ethif >>= fun ipv4 ->
or_error "udpv4" S.U.connect ipv4 >>= fun udpv4 ->
or_error "tcpv4" S.T.connect ipv4 >>= fun tcpv4 ->
let config = { = "stack";
Mirage_types_lwt.console = c;
Mirage_types_lwt.interface = netif;
Mirage_types_lwt.mode = `IPv4 (ip, netmask, gw);
} in
or_error "stack" (S.connect config ethif ipv4 udpv4) tcpv4
We can now create multiple stacks that talk over the same backend. `Basic_backend.create` accepts two optional parameters:
- `use_async_readers` makes the `write` calls non-blocking. This is necessary to use Vnetif with the Mirage TCP/IP stack.
- `yield` specifies the yield function to use in non-blocking mode. In a unikernel this is typically `OS.Time.sleep 0.0`, but in a Unix process `Lwt_main.yield ()` can be used instead.
let () =
(* create async backend with OS.Time.sleep 0.0 as yield *)
let backend = Basic_backend.create ~use_async_readers:true
~yield:(fun() -> OS.Time.sleep 0.0 ) () in
let netmask = Ipaddr.V4.of_string_exn "" in
let gw = Ipaddr.V4.of_string_exn "" in
let server_ip = Ipaddr.V4.of_string_exn "" in
create_stack c backend server_ip netmask [gw] >>= fun server_stack ->
let client_ip = Ipaddr.V4.of_string_exn "" in
create_stack c backend server_ip netmask [gw] >>= fun client_stack ->
The stacks can now be used as regular Mirage TCP/IP stacks, e.g.:
S.listen_tcpv4 server_stack ~port:80 (fun f -> ...);
S.listen s1
## Build examples
mirage configure --xen/--unix
url {
archive: ""
checksum: "5b8e5c8fd0b1eb93d5296b03d62eb0b7"