Allow datagram_socket to be created without address (#360)

* net: allow to create udp socket without address * udp: add udp test * udp: allow Eio.Net.Sockaddr.t in datagram_socket() without casting * udp: add reuse_addr and reuse_port to datagram_socket * Simplify tests Removed the last IPv6 test since it was identical to an earlier test. * Simplify luv code * Move socket options out of Eio_unix * Simplify eio_linux code Fix problem that UDP sockets were not created close-on-exec. Co-authored-by: Thomas Leonard <talex5@gmail.com>
ocaml-multicore · Nov 4, 2022 · a70865e · a70865e
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diff --git a/lib_eio/mock/net.ml b/lib_eio/mock/net.ml
@@ -36,8 +36,12 @@ let make label =
       Switch.on_release sw (fun () -> Eio.Flow.close socket);
       socket
 
-    method datagram_socket ~sw addr =
-      traceln "%s: datagram_socket %a" label Eio.Net.Sockaddr.pp addr;
+    method datagram_socket ~reuse_addr:_ ~reuse_port:_ ~sw addr =
+      (match addr with
+      | `Udp _ as saddr -> traceln "%s: datagram_socket %a" label Eio.Net.Sockaddr.pp saddr
+      | `UdpV4 -> traceln "%s: datagram_socket UDPv4" label
+      | `UdpV6 -> traceln "%s: datagram_socket UDPv6" label
+      );
       let socket = Handler.run on_datagram_socket in
       Switch.on_release sw (fun () -> Eio.Flow.close socket);
       socket

diff --git a/lib_eio/net.ml b/lib_eio/net.ml
@@ -180,15 +180,23 @@ let recv (t:#datagram_socket) = t#recv
 class virtual t = object
   method virtual listen : reuse_addr:bool -> reuse_port:bool -> backlog:int -> sw:Switch.t -> Sockaddr.stream -> listening_socket
   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 datagram_socket :
+       reuse_addr:bool
+    -> reuse_port:bool
+    -> sw:Switch.t
+    -> [Sockaddr.datagram | `UdpV4 | `UdpV6]
+    -> <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
 let connect ~sw (t:#t) = t#connect ~sw
 
-let datagram_socket ~sw (t:#t) = t#datagram_socket ~sw
+let datagram_socket ?(reuse_addr=false) ?(reuse_port=false) ~sw (t:#t) addr =
+  let addr = (addr :> [Sockaddr.datagram | `UdpV4 | `UdpV6]) in 
+  t#datagram_socket ~reuse_addr ~reuse_port ~sw addr
 
 let getaddrinfo ?(service="") (t:#t) hostname = t#getaddrinfo ~service hostname
 

diff --git a/lib_eio/net.mli b/lib_eio/net.mli
@@ -104,7 +104,13 @@ end
 class virtual t : object
   method virtual listen : reuse_addr:bool -> reuse_port:bool -> backlog:int -> sw:Switch.t -> Sockaddr.stream -> listening_socket
   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 datagram_socket :
+       reuse_addr:bool
+    -> reuse_port:bool
+    -> sw:Switch.t
+    -> [Sockaddr.datagram | `UdpV4 | `UdpV6]
+    -> <datagram_socket; Flow.close>
+
   method virtual getaddrinfo : service:string -> string -> Sockaddr.t list
   method virtual getnameinfo : Sockaddr.t -> (string * string)
 end
@@ -187,9 +193,23 @@ val accept_sub :
 
 (** {2 Datagram Sockets} *)
 
-val datagram_socket : sw:Switch.t -> #t -> Sockaddr.datagram -> <datagram_socket; Flow.close>
-(** [datagram_socket ~sw t addr] creates a new datagram socket that data can be sent to
-    and received from. The new socket will be closed when [sw] finishes. *)
+val datagram_socket :
+     ?reuse_addr:bool
+  -> ?reuse_port:bool
+  -> sw:Switch.t
+  -> #t
+  -> [< Sockaddr.datagram | `UdpV4 | `UdpV6]
+  -> <datagram_socket; Flow.close>
+  (** [datagram_socket ~sw t addr] creates a new datagram socket bound to [addr]. The new 
+      socket will be closed when [sw] finishes. 
+
+      [`UdpV4] and [`UdpV6] represents IPv4 and IPv6
+      datagram client sockets where the OS assigns the next available socket address and port
+      automatically. [`Udp ..] can be used to create both listening server socket and client 
+      socket.
+
+      @param reuse_addr Set the {!Unix.SO_REUSEADDR} socket option.
+      @param reuse_port Set the {!Unix.SO_REUSEPORT} socket option. *)
 
 val send : #datagram_socket -> Sockaddr.datagram -> Cstruct.t -> unit
 (** [send sock addr buf] sends the data in [buf] to the address [addr] using the 

diff --git a/lib_eio_linux/eio_linux.ml b/lib_eio_linux/eio_linux.ml
@@ -1129,6 +1129,8 @@ end
 
 let socket_domain_of = function
   | `Unix _ -> Unix.PF_UNIX
+  | `UdpV4 -> Unix.PF_INET
+  | `UdpV6 -> Unix.PF_INET6
   | `Udp (host, _)
   | `Tcp (host, _) ->
     Eio.Net.Ipaddr.fold host
@@ -1183,17 +1185,21 @@ let net = object
     Low_level.connect sock addr;
     (flow sock :> <Eio.Flow.two_way; Eio.Flow.close>)
 
-  method datagram_socket ~sw saddr =
-    match saddr with
+  method datagram_socket ~reuse_addr ~reuse_port ~sw saddr =
+    let sock_unix = Unix.socket ~cloexec:true (socket_domain_of saddr) Unix.SOCK_DGRAM 0 in
+    let sock = FD.of_unix ~sw ~seekable:false ~close_unix:true sock_unix in
+    begin match saddr with
     | `Udp (host, port) ->
       let host = Eio_unix.Ipaddr.to_unix host in
       let addr = Unix.ADDR_INET (host, port) in
-      let sock_unix = Unix.socket (socket_domain_of saddr) Unix.SOCK_DGRAM 0 in
-      Unix.setsockopt sock_unix Unix.SO_REUSEADDR true;
-      Unix.setsockopt sock_unix Unix.SO_REUSEPORT true;
-      let sock = FD.of_unix ~sw ~seekable:false ~close_unix:true sock_unix in
-      Unix.bind sock_unix addr;
-      udp_socket sock
+      if reuse_addr then
+        Unix.setsockopt sock_unix Unix.SO_REUSEADDR true;
+      if reuse_port then
+        Unix.setsockopt sock_unix Unix.SO_REUSEPORT true;
+      Unix.bind sock_unix addr
+    | `UdpV4 | `UdpV6 -> ()
+    end;
+    udp_socket sock
 
   method getaddrinfo = Low_level.getaddrinfo
 

diff --git a/lib_eio_luv/eio_luv.ml b/lib_eio_luv/eio_luv.ml
@@ -827,6 +827,15 @@ let listening_unix_socket ~backlog sock = object
     `Unix (Luv.Pipe.getpeername (Handle.get "get_client_addr" c) |> or_raise)
 end
 
+let socket_domain_of = function
+  | `UdpV4 -> `INET
+  | `UdpV6 -> `INET6
+  | `Udp (host, _)
+  | `Tcp (host, _) ->
+    Eio.Net.Ipaddr.fold host
+      ~v4:(fun _ -> `INET)
+      ~v6:(fun _ -> `INET6)
+
 let net = object
   inherit Eio.Net.t
 
@@ -861,14 +870,19 @@ let net = object
       let sock = Stream.connect_pipe ~sw path in
       (socket sock :> < Eio.Flow.two_way; Eio.Flow.close >)
 
-  method datagram_socket ~sw = function
+  method datagram_socket ~reuse_addr ~reuse_port ~sw saddr =
+    let domain = socket_domain_of saddr in
+    let sock = Luv.UDP.init ~domain ~loop:(get_loop ()) () |> or_raise in
+    let dg_sock = Handle.of_luv ~sw sock in
+    begin match saddr with
     | `Udp (host, port) ->
-      let domain = Eio.Net.Ipaddr.fold ~v4:(fun _ -> `INET) ~v6:(fun _ -> `INET6) host in
-      let sock = Luv.UDP.init ~domain ~loop:(get_loop ()) () |> or_raise in
-      let dg_sock = Handle.of_luv ~sw sock in
       let addr = luv_addr_of_eio host port in
-      Luv.UDP.bind sock addr |> or_raise;
-      udp_socket dg_sock
+      luv_reuse_addr sock reuse_addr;
+      luv_reuse_port sock reuse_port;
+      Luv.UDP.bind sock addr |> or_raise
+    | `UdpV4 | `UdpV6 -> ()
+    end;
+    udp_socket dg_sock
 
   method getaddrinfo = Low_level.getaddrinfo
 

diff --git a/tests/network.md b/tests/network.md
@@ -204,6 +204,49 @@ Handling one UDP packet using IPv6:
 - : unit = ()
 ```
 
+Now test host-assigned addresses.
+`run_dgram2` is like `run_dgram` above, but doesn't print the sender address
+since it will be different in each run:
+
+```ocaml
+let run_dgram2 ~e1 addr ~net sw =
+  let server_addr = `Udp (addr, 8082) in
+  let listening_socket = Eio.Net.datagram_socket ~sw net server_addr in
+  Fiber.both
+    (fun () ->
+      let buf = Cstruct.create 20 in
+      traceln "Waiting to receive data on %a" Eio.Net.Sockaddr.pp server_addr;
+      let addr, recv = Eio.Net.recv listening_socket buf in
+      traceln "Received message %s" (Cstruct.(to_string (sub buf 0 recv)))
+    )
+    (fun () ->
+      let e = Eio.Net.datagram_socket ~sw net e1 in
+      traceln "Sending data to %a" Eio.Net.Sockaddr.pp server_addr;
+      Eio.Net.send e server_addr (Cstruct.of_string "UDP Message"));;
+```
+
+Handling one UDP packet using IPv4:
+
+```ocaml
+# let addr = Eio.Net.Ipaddr.V4.loopback in
+  run @@ run_dgram2 addr ~e1:`UdpV4;;
++Waiting to receive data on udp:127.0.0.1:8082
++Sending data to udp:127.0.0.1:8082
++Received message UDP Message
+- : unit = ()
+```
+
+Handling one UDP packet using IPv6:
+
+```ocaml
+# let addr = Eio.Net.Ipaddr.V6.loopback in
+  run @@ run_dgram2 addr ~e1:`UdpV6;;
++Waiting to receive data on udp:[::1]:8082
++Sending data to udp:[::1]:8082
++Received message UDP Message
+- : unit = ()
+```
+
 ## Unix interop
 
 Extracting file descriptors from Eio objects: