(draft) Eio.Net.connect: optionally bind before connect

lib_eio/mock/net.ml

@@ -36,7 +36,7 @@ module Impl = struct
     Switch.on_release sw (fun () -> Eio.Resource.close socket);
     socket
 
-  let connect t ~sw addr =
+  let connect t ~sw ~options:_ addr =
     traceln "%s: connect to %a" t.label Eio.Net.Sockaddr.pp addr;
     let socket = Handler.run t.on_connect in
     Switch.on_release sw (fun () -> Eio.Flow.close socket);

lib_eio/net.ml

@@ -180,6 +180,12 @@ type 'tag ty = [`Network | `Platform of 'tag]
 type 'a t = 'a r
   constraint 'a = [> [> `Generic] ty]
 
+type option = ..
+type option +=
+  | Source_addr of Sockaddr.stream
+  | Reuse_addr
+  | Reuse_port
+
 module Pi = struct
   module type STREAM_SOCKET = sig
     type tag
@@ -235,7 +241,7 @@ module Pi = struct
     type tag
 
     val listen : t -> reuse_addr:bool -> reuse_port:bool -> backlog:int -> sw:Switch.t -> Sockaddr.stream -> tag listening_socket_ty r
-    val connect : t -> sw:Switch.t -> Sockaddr.stream -> tag stream_socket_ty r
+    val connect : t -> sw:Switch.t -> options:option list -> Sockaddr.stream -> tag stream_socket_ty r
     val datagram_socket :
       t
       -> reuse_addr:bool
@@ -295,10 +301,10 @@ let listen (type tag) ?(reuse_addr=false) ?(reuse_port=false) ~backlog ~sw (t:[>
   let module X = (val (Resource.get ops Pi.Network)) in
   X.listen t ~reuse_addr ~reuse_port ~backlog ~sw
 
-let connect (type tag) ~sw (t:[> tag ty] r) addr =
+let connect (type tag) ~sw ?(options = []) (t:[> tag ty] r) addr =
   let (Resource.T (t, ops)) = t in
   let module X = (val (Resource.get ops Pi.Network)) in
-  try X.connect t ~sw addr
+  try X.connect t ~sw ~options addr
   with Exn.Io _ as ex ->
     let bt = Printexc.get_raw_backtrace () in
     Exn.reraise_with_context ex bt "connecting to %a" Sockaddr.pp addr

lib_eio/net.mli

@@ -129,7 +129,13 @@ type 'a t = 'a r
 
 (** {2 Out-bound Connections} *)
 
-val connect : sw:Switch.t -> [> 'tag ty] t -> Sockaddr.stream -> 'tag stream_socket_ty r
+type option = ..
+type option +=
+  | Source_addr of Sockaddr.stream
+  | Reuse_addr
+  | Reuse_port
+
+val connect : sw:Switch.t -> ?options:option list -> [> 'tag ty] t -> Sockaddr.stream -> 'tag stream_socket_ty r
 (** [connect ~sw t addr] is a new socket connected to remote address [addr].
 
     The new socket will be closed when [sw] finishes, unless closed manually first. *)
@@ -346,7 +352,7 @@ module Pi : sig
       t -> reuse_addr:bool -> reuse_port:bool -> backlog:int -> sw:Switch.t ->
       Sockaddr.stream -> tag listening_socket_ty r
 
-    val connect : t -> sw:Switch.t -> Sockaddr.stream -> tag stream_socket_ty r
+    val connect : t -> sw:Switch.t -> options:option list -> Sockaddr.stream -> tag stream_socket_ty r
 
     val datagram_socket :
       t

lib_eio/unix/net.ml

@@ -85,3 +85,15 @@ let socketpair_datagram ~sw ?(domain=Unix.PF_UNIX) ?(protocol=0) () =
 
 let fd socket =
   Option.get (Resource.fd_opt socket)
+
+let apply_option fd = function
+  | Eio.Net.Source_addr addr ->
+      Unix.bind fd (sockaddr_to_unix addr)
+  | Eio.Net.Reuse_addr ->
+      Unix.setsockopt fd Unix.SO_REUSEADDR true
+  | Eio.Net.Reuse_port ->
+      Unix.setsockopt fd Unix.SO_REUSEPORT true
+  | _ ->
+      invalid_arg "Unknown Eio.Net.option"
+
+let configure options fd = List.iter (apply_option fd) options

lib_eio/unix/net.mli

@@ -97,6 +97,9 @@ val socketpair_datagram :
 val getnameinfo : Eio.Net.Sockaddr.t -> (string * string)
 (** [getnameinfo sockaddr] returns domain name and service for [sockaddr]. *)
 
+val configure : Eio.Net.option list -> Unix.file_descr -> unit
+(** [configure options fd] prepare the socket with the chosen options. *)
+
 type _ Effect.t +=
   | Import_socket_stream :
       Switch.t * bool * Unix.file_descr -> [`Unix_fd | stream_socket_ty] r Effect.t     (** See {!import_socket_stream} *)

lib_eio_linux/eio_linux.ml

@@ -249,11 +249,11 @@ let socket_domain_of = function
       ~v4:(fun _ -> Unix.PF_INET)
       ~v6:(fun _ -> Unix.PF_INET6)
 
-let connect ~sw connect_addr =
+let connect ~sw ~options connect_addr =
   let addr = Eio_unix.Net.sockaddr_to_unix connect_addr in
   let sock_unix = Unix.socket ~cloexec:true (socket_domain_of connect_addr) Unix.SOCK_STREAM 0 in
   let sock = Fd.of_unix ~sw ~seekable:false ~close_unix:true sock_unix in
-  Low_level.connect sock addr;
+  Low_level.connect sock ~options addr;
   (flow sock :> _ Eio_unix.Net.stream_socket)
 
 module Impl = struct
@@ -289,7 +289,8 @@ module Impl = struct
     Unix.listen sock_unix backlog;
     (listening_socket sock :> _ Eio.Net.listening_socket_ty r)
 
-  let connect () ~sw addr = (connect ~sw addr :> [`Generic | `Unix] Eio.Net.stream_socket_ty r)
+  let connect () ~sw ~options addr =
+    (connect ~sw ~options addr :> [`Generic | `Unix] Eio.Net.stream_socket_ty r)
 
   let datagram_socket () ~reuse_addr ~reuse_port ~sw saddr =
     if reuse_addr then (

lib_eio_linux/low_level.ml

@@ -221,8 +221,9 @@ let splice src ~dst ~len =
   else if res = 0 then raise End_of_file
   else raise @@ Err.wrap (Uring.error_of_errno res) "splice" ""
 
-let connect fd addr =
+let connect fd ~options addr =
   Fd.use_exn "connect" fd @@ fun fd ->
+  Eio_unix.Net.configure options fd ;
   let res = Sched.enter "connect" (enqueue_connect fd addr) in
   if res < 0 then (
     let ex =

lib_eio_linux/low_level.mli

@@ -111,8 +111,9 @@ val splice : fd -> dst:fd -> len:int -> int
     @raise End_of_file [src] is at the end of the file.
     @raise Unix.Unix_error(EINVAL, "splice", _) if splice is not supported for these FDs. *)
 
-val connect : fd -> Unix.sockaddr -> unit
-(** [connect fd addr] attempts to connect socket [fd] to [addr]. *)
+val connect : fd -> options:Eio.Net.option list -> Unix.sockaddr -> unit
+(** [connect fd ~options addr] attempts to connect socket [fd] to [addr]
+    after configuring the socket with [options]. *)
 
 val await_readable : fd -> unit
 (** [await_readable fd] blocks until [fd] is readable (or has an error). *)

lib_eio_posix/low_level.ml

@@ -67,15 +67,18 @@ let socket ~sw socket_domain socket_type protocol =
   Unix.set_nonblock sock_unix;
   Fd.of_unix ~sw ~blocking:false ~close_unix:true sock_unix
 
-let connect fd addr =
+let connect fd ~options addr =
   try
-    Fd.use_exn "connect" fd (fun fd -> Unix.connect fd addr)
+    Fd.use_exn "connect" fd @@ fun fd ->
+    Eio_unix.Net.configure options fd ;
+    Unix.connect fd addr
   with
   | Unix.Unix_error ((EINTR | EAGAIN | EWOULDBLOCK | EINPROGRESS), _, _) ->
     await_writable "connect" fd;
-    match Fd.use_exn "connect" fd Unix.getsockopt_error with
+    (match Fd.use_exn "connect" fd Unix.getsockopt_error with
     | None -> ()
-    | Some code -> raise (Err.wrap code "connect-in-progress" "")
+    | Some code -> raise (Err.wrap code "connect-in-progress" ""))
+  | Unix.Unix_error (code, name, arg) -> raise (Err.wrap code name arg)
 
 let accept ~sw sock =
   Fd.use_exn "accept" sock @@ fun sock ->

lib_eio_posix/low_level.mli

@@ -28,7 +28,7 @@ val read : fd -> bytes -> int -> int -> int
 val write : fd -> bytes -> int -> int -> int
 
 val socket : sw:Switch.t -> Unix.socket_domain -> Unix.socket_type -> int -> fd
-val connect : fd -> Unix.sockaddr -> unit
+val connect : fd -> options:Eio.Net.option list -> Unix.sockaddr -> unit
 val accept : sw:Switch.t -> fd -> fd * Unix.sockaddr
 
 val shutdown : fd -> Unix.shutdown_command -> unit

lib_eio_posix/net.ml

@@ -138,7 +138,7 @@ let listen ~reuse_addr ~reuse_port ~backlog ~sw (listen_addr : Eio.Net.Sockaddr.
     );
   (listening_socket ~hook sock :> _ Eio.Net.listening_socket_ty r)
 
-let connect ~sw connect_addr =
+let connect ~sw ~options connect_addr =
   let socket_type, addr =
     match connect_addr with
     | `Unix path         -> Unix.SOCK_STREAM, Unix.ADDR_UNIX path
@@ -148,7 +148,7 @@ let connect ~sw connect_addr =
   in
   let sock = Low_level.socket ~sw (socket_domain_of connect_addr) socket_type 0 in
   try
-    Low_level.connect sock addr;
+    Low_level.connect sock ~options addr;
     (Flow.of_fd sock :> _ Eio_unix.Net.stream_socket)
   with Unix.Unix_error (code, name, arg) -> raise (Err.wrap code name arg)
 
@@ -174,8 +174,8 @@ module Impl = struct
 
   let listen () = listen
 
-  let connect () ~sw addr =
-    let socket = connect ~sw addr in
+  let connect () ~sw ~options addr =
+    let socket = connect ~sw ~options addr in
     (socket :> [`Generic | `Unix] Eio.Net.stream_socket_ty r)
 
   let datagram_socket () ~reuse_addr ~reuse_port ~sw saddr =

lib_eio_windows/low_level.ml

@@ -60,15 +60,18 @@ let socket ~sw socket_domain socket_type protocol =
   Unix.set_nonblock sock_unix;
   Fd.of_unix ~sw ~blocking:false ~close_unix:true sock_unix
 
-let connect fd addr =
+let connect fd ~options addr =
   try
-    Fd.use_exn "connect" fd (fun fd -> Unix.connect fd addr)
+    Fd.use_exn "connect" fd @@ fun fd ->
+    Eio_unix.Net.configure options fd ;
+    Unix.connect fd addr
   with
   | Unix.Unix_error ((EINTR | EAGAIN | EWOULDBLOCK | EINPROGRESS), _, _) ->
     await_writable fd;
     match Fd.use_exn "connect" fd Unix.getsockopt_error with
     | None -> ()
     | Some code -> raise (Err.wrap code "connect-in-progress" "")
+  | Unix.Unix_error (code, name, arg) -> raise (Err.wrap code name arg)
 
 let accept ~sw sock =
   Fd.use_exn "accept" sock @@ fun sock ->

lib_eio_windows/low_level.mli

@@ -24,7 +24,7 @@ val read_cstruct : fd -> Cstruct.t -> int
 val write : fd -> bytes -> int -> int -> int
 
 val socket : sw:Switch.t -> Unix.socket_domain -> Unix.socket_type -> int -> fd
-val connect : fd -> Unix.sockaddr -> unit
+val connect : fd -> options:Eio.Net.option list -> Unix.sockaddr -> unit
 val accept : sw:Switch.t -> fd -> fd * Unix.sockaddr
 
 val shutdown : fd -> Unix.shutdown_command -> unit

lib_eio_windows/net.ml

@@ -142,7 +142,7 @@ let listen ~reuse_addr ~reuse_port ~backlog ~sw (listen_addr : Eio.Net.Sockaddr.
     );
   (listening_socket ~hook sock :> _ Eio.Net.listening_socket_ty r)
 
-let connect ~sw connect_addr =
+let connect ~sw ~options connect_addr =
   let socket_type, addr =
     match connect_addr with
     | `Unix path         -> Unix.SOCK_STREAM, Unix.ADDR_UNIX path
@@ -152,7 +152,7 @@ let connect ~sw connect_addr =
   in
   let sock = Low_level.socket ~sw (socket_domain_of connect_addr) socket_type 0 in
   try
-    Low_level.connect sock addr;
+    Low_level.connect sock ~options addr;
     (Flow.of_fd sock :> _ Eio_unix.Net.stream_socket)
   with Unix.Unix_error (code, name, arg) -> raise (Err.wrap code name arg)