package mimic-happy-eyeballs

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Parameters
Signature

mimic-happy-eyeballs
- Mimic_happy_eyeballs
  - Make
    
    DNS
    
    Transport
    
    Happy_eyeballs
    
    Stack
    
    IP
    
    TCP
    
    UDP
  - S

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Class type

The functor used by the MirageOS to prepare the Mimic.ctx from an already allocated happy_eyeballs resource which is able to allocate a TCP/IP connection from a destination regardless the target chosen by the user.

Parameters

module Stack : Tcpip.Stack.V4V6

module DNS : Dns_client_mirage.S with type Transport.stack = Stack.t

module Happy_eyeballs : 
  Happy_eyeballs_mirage.S
    with module Transport = DNS.Transport
     and type dns = DNS.t
     and type flow = Stack.TCP.flow

Signature

include S with type t = Happy_eyeballs.t and type flow = Stack.TCP.flow

type t = Happy_eyeballs.t

type flow = Stack.TCP.flow

val happy_eyeballs : t Mimic.value

val resolve : 
  t ->
  string ->
  int list ->
  ((Ipaddr.t * int) * flow, [> `Msg of string ]) Stdlib.result Lwt.t

resolve happy_eyeballs domain_name ports tries to connect the user with the given endpoint. The domain-name can be an IP address or a real domain-name. resolve tries to resolve via a DNS request the given domain_name if it's a real domain-name and it tries to initiate a TCP/IP connection with the destination.

If it's a success, it returns the resource and the user is able to read or write via this resource.

val connect : t -> Mimic.ctx Lwt.t

connect happy_eyeballs returns a Mimic.ctx which contains an happy_eyeballs value which can be used and re-used by some others devices which want to resolve a domain-name.

More concretely, the user is able to describe a sub-process to allocate a flow from some Mimic's values:

(* main.ml, generated by the mirage tool *)

include Make (Stack) (Dns) (Happy_eyeballs)
let domain_name : string Mimic.value =
  Mimic.make ~name:"domain-name"

let ctx happy_eyeballs_v =
  let open Lwt.Infix in
  let k0 happy_eyeballs domain_name =
    resolve happy_eyeballs domain_name [ 80 ] >>= function
    | Ok (_, flow) -> Lwt.return_some flow
    | Error _ -> Lwt.return_none in
  connect happy_eyeballs_v >|=
  Mimic.fold edn Mimic.Fun.[ req happy_eyeballs; req domain_name ]
    ~k:k0

(* unikernel.ml *)

let run ~ctx = Mimic.resolve ctx >>= function
  | Ok flow -> (* ... *)
  | Error (`Msg err) -> failwith err