Eio.Net: add getnameinfo

lib_eio/mock/eio_mock.mli

@@ -122,6 +122,7 @@ module Net : sig
     on_connect : <Eio.Net.stream_socket; Eio.Flow.close> Handler.t;
     on_datagram_socket : <Eio.Net.datagram_socket; Eio.Flow.close> Handler.t;
     on_getaddrinfo : Eio.Net.Sockaddr.t list Handler.t;
+    on_getnameinfo : (string * string) Handler.t;
   >
 
   type listening_socket = <
@@ -143,6 +144,8 @@ module Net : sig
 
   val on_getaddrinfo : t -> Eio.Net.Sockaddr.t list Handler.actions -> unit
 
+  val on_getnameinfo : t -> (string * string) Handler.actions -> unit
+
   val listening_socket : string -> listening_socket
   (** [listening_socket label] can be configured to provide mock connections. *)
 

lib_eio/mock/net.ml

@@ -6,20 +6,23 @@ type t = <
   on_connect : <Eio.Net.stream_socket; Eio.Flow.close> Handler.t;
   on_datagram_socket : <Eio.Net.datagram_socket; Eio.Flow.close> Handler.t;
   on_getaddrinfo : Eio.Net.Sockaddr.t list Handler.t;
+  on_getnameinfo : (string * string) Handler.t;
 >
 
 let make label =
   let on_listen = Handler.make (`Raise (Failure "Mock listen handler not configured")) in
   let on_connect = Handler.make (`Raise (Failure "Mock connect handler not configured")) in
   let on_datagram_socket = Handler.make (`Raise (Failure "Mock datagram_socket handler not configured")) in
   let on_getaddrinfo = Handler.make (`Raise (Failure "Mock getaddrinfo handler not configured")) in
+  let on_getnameinfo = Handler.make (`Raise (Failure "Mock getnameinfo handler not configured")) in
   object
     inherit Eio.Net.t
 
     method on_listen = on_listen
     method on_connect = on_connect
     method on_datagram_socket = on_datagram_socket
     method on_getaddrinfo = on_getaddrinfo
+    method on_getnameinfo = on_getnameinfo
 
     method listen ~reuse_addr:_ ~reuse_port:_ ~backlog:_ ~sw addr =
       traceln "%s: listen on %a" label Eio.Net.Sockaddr.pp addr;
@@ -42,6 +45,10 @@ let make label =
     method getaddrinfo ~service node =
       traceln "%s: getaddrinfo ~service:%s %s" label service node;
       Handler.run on_getaddrinfo
+
+    method getnameinfo sockaddr =
+      traceln "%s: getnameinfo %a" label Eio.Net.Sockaddr.pp sockaddr;
+      Handler.run on_getnameinfo
   end
 
 let on_connect (t:t) actions =
@@ -58,6 +65,8 @@ let on_datagram_socket (t:t) actions =
 
 let on_getaddrinfo (t:t) actions = Handler.seq t#on_getaddrinfo actions
 
+let on_getnameinfo (t:t) actions = Handler.seq t#on_getnameinfo actions
+
 type listening_socket = <
   Eio.Net.listening_socket;
   on_accept : (Flow.t * Eio.Net.Sockaddr.stream) Handler.t;

lib_eio/net.ml

@@ -181,6 +181,7 @@ class virtual t = object
   method virtual connect : sw:Switch.t -> Sockaddr.stream -> <stream_socket; Flow.close>
   method virtual datagram_socket : sw:Switch.t -> Sockaddr.datagram -> <datagram_socket; Flow.close>
   method virtual getaddrinfo : service:string -> string -> Sockaddr.t list
+  method virtual getnameinfo : Sockaddr.t -> (string * string)
 end
 
 let listen ?(reuse_addr=false) ?(reuse_port=false) ~backlog ~sw (t:#t) = t#listen ~reuse_addr ~reuse_port ~backlog ~sw
@@ -190,4 +191,6 @@ let datagram_socket ~sw (t:#t) = t#datagram_socket ~sw
 
 let getaddrinfo ?(service="") (t:#t) hostname = t#getaddrinfo ~service hostname
 
+let getnameinfo (t:#t) sockaddr = t#getnameinfo sockaddr
+
 let close = Flow.close

lib_eio/net.mli

@@ -105,6 +105,7 @@ class virtual t : object
   method virtual connect : sw:Switch.t -> Sockaddr.stream -> <stream_socket; Flow.close>
   method virtual datagram_socket : sw:Switch.t -> Sockaddr.datagram -> <datagram_socket; Flow.close>
   method virtual getaddrinfo : service:string -> string -> Sockaddr.t list
+  method virtual getnameinfo : Sockaddr.t -> (string * string)
 end
 
 (** {2 Out-bound Connections} *)
@@ -183,6 +184,11 @@ val getaddrinfo: ?service:string -> #t -> string -> Sockaddr.t list
 
     For a more thorough treatment, @see <https://man7.org/linux/man-pages/man3/getaddrinfo.3.html> getaddrinfo *)
 
+val getnameinfo : #t -> Sockaddr.t -> (string * string)
+(** [getnameinfo t sockaddr] is [(hostname, service)] corresponding to [sockaddr]. [hostname] is the
+    registered domain name represented by [sockaddr]. [service] is the IANA specified textual name of the
+    port specified in [sockaddr], e.g. 'ftp', 'http', 'https', etc. *)
+
 (** {2 Closing} *)
 val close : <close: unit; ..> -> unit
 (** [close t] marks the socket as closed. It can no longer be used after this. *)

lib_eio/unix/eio_unix.ml

@@ -54,3 +54,14 @@ module Ipaddr = struct
 end
 
 module Ctf = Ctf_unix
+
+let getnameinfo (sockaddr : Eio.Net.Sockaddr.t) =
+  let sockaddr, options =
+    match sockaddr with
+    | `Unix s -> (Unix.ADDR_UNIX s, [])
+    | `Tcp (addr, port) -> (Unix.ADDR_INET (Ipaddr.to_unix addr, port), [])
+    | `Udp (addr, port) -> (Unix.ADDR_INET (Ipaddr.to_unix addr, port), [Unix.NI_DGRAM])
+  in
+  run_in_systhread (fun () ->
+    let Unix.{ni_hostname; ni_service} = Unix.getnameinfo sockaddr options in
+    (ni_hostname, ni_service))

lib_eio/unix/eio_unix.mli

@@ -93,3 +93,6 @@ module Private : sig
 end
 
 module Ctf = Ctf_unix
+
+val getnameinfo : Eio.Net.Sockaddr.t -> (string * string)
+(** [getnameinfo sockaddr] returns domain name and service for [sockaddr]. *)

lib_eio_linux/eio_linux.ml

@@ -908,7 +908,7 @@ module Low_level = struct
     in
     Eio_unix.run_in_systhread @@ fun () ->
     Unix.getaddrinfo node service []
-    |> List.filter_map to_eio_sockaddr_t    
+    |> List.filter_map to_eio_sockaddr_t
 end
 
 external eio_eventfd : int -> Unix.file_descr = "caml_eio_eventfd"
@@ -1139,6 +1139,8 @@ let net = object
       udp_socket sock
 
   method getaddrinfo = Low_level.getaddrinfo
+
+  method getnameinfo = Eio_unix.getnameinfo
 end
 
 type stdenv = <

lib_eio_linux/eio_linux.mli

@@ -253,5 +253,4 @@ module Low_level : sig
   val getaddrinfo : service:string -> string -> Eio.Net.Sockaddr.t list
   (** [getaddrinfo host] returns a list of IP addresses for [host]. [host] is either a domain name or
       an ipaddress. *)
-
 end

lib_eio_luv/eio_luv.ml

@@ -116,6 +116,17 @@ let get_loop () =
   enter_unchecked @@ fun t k ->
   Suspended.continue k t.loop
 
+let luv_addr_of_eio host port =
+  let host = Unix.string_of_inet_addr (Eio_unix.Ipaddr.to_unix host) in
+  match Luv.Sockaddr.ipv6 host port with
+  | Ok addr -> addr
+  | Error _ -> Luv.Sockaddr.ipv4 host port |> or_raise
+
+let luv_ip_addr_to_eio addr =
+  let host = Luv.Sockaddr.to_string addr |> Option.get in
+  let port = Luv.Sockaddr.port addr |> Option.get in
+  (Eio_unix.Ipaddr.of_unix (Unix.inet_addr_of_string host), port)
+
 module Low_level = struct
   type 'a or_error = ('a, Luv.Error.t) result
 
@@ -428,7 +439,6 @@ module Low_level = struct
     await_with_cancel ~request (fun loop -> Luv.DNS.getaddrinfo ~loop ~request ~service ~node ())
     |> or_raise
     |> List.filter_map to_eio_sockaddr_t
-
 end
 
 open Low_level
@@ -549,17 +559,6 @@ end
 let luv_reuse_addr _sock _v = ()
 let luv_reuse_port _sock _v = ()
 
-let luv_addr_of_eio host port =
-  let host = Unix.string_of_inet_addr (Eio_unix.Ipaddr.to_unix host) in
-  match Luv.Sockaddr.ipv6 host port with
-  | Ok addr -> addr
-  | Error _ -> Luv.Sockaddr.ipv4 host port |> or_raise
-
-let luv_ip_addr_to_eio addr =
-  let host = Luv.Sockaddr.to_string addr |> Option.get in
-  let port = Luv.Sockaddr.port addr |> Option.get in
-  (Eio_unix.Ipaddr.of_unix (Unix.inet_addr_of_string host), port)
-
 module Udp = struct
   type 'a t = [`UDP] Handle.t
 
@@ -671,6 +670,8 @@ let net = object
       udp_socket dg_sock
 
   method getaddrinfo = Low_level.getaddrinfo
+
+  method getnameinfo = Eio_unix.getnameinfo
 end
 
 let secure_random =

tests/network.md

@@ -527,3 +527,12 @@ EPIPE:
  `Tcp ("*\000\020P@\t\b \000\000\000\000\000\000 \014", 443);
  `Udp ("*\000\020P@\t\b \000\000\000\000\000\000 \014", 443)]
 ```
+
+## getnameinfo
+
+```ocaml
+# Eio_main.run @@ fun env ->
+  let sockaddr = `Tcp (Eio.Net.Ipaddr.V4.loopback, 80) in
+  Eio.Net.getnameinfo env#net sockaddr;;
+- : string * string = ("localhost", "http")
+```