Merge pull request atomvm#1491 from pguyot/w04/connect-to-localhost-with-shortnames

Resolve short names using .local suffix with `inet:getaddr/2`

This allows to connect to localhost if shortnames are used and host cannot be
resolved. BEAM succeeds even if gethostbyname(2) fails, typically on macOS 15.

These changes are made under both the "Apache 2.0" and the "GNU Lesser General
Public License 2.1 or later" license terms (dual license).

SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later

Author: bettio

libs/estdlib/src/inet.erl

@@ -108,6 +108,29 @@ getaddr(Name, Family) ->
                 [] -> {error, nxdomain};
                 [IPAddr | _] -> {ok, IPAddr}
             end;
+        {error, eainoname} ->
+            case string:split(Name, ".") of
+                [Name] ->
+                    % BEAM succeeds to resolve short names even if gethostbyname(2) fails.
+                    % Work around for distribution by trying to add .local suffix.
+                    case net:getaddrinfo(Name ++ ".local") of
+                        {ok, ResultsLocal} ->
+                            FilteredLocal = [
+                                Addr
+                             || #{family := F, addr := #{addr := Addr}} <- ResultsLocal,
+                                F =:= Family,
+                                Addr =:= {127, 0, 0, 1} orelse Addr =:= {0, 0, 0, 0, 0, 0, 0, 1}
+                            ],
+                            case FilteredLocal of
+                                [] -> {error, nxdomain};
+                                [LocalIPAddr | _] -> {ok, LocalIPAddr}
+                            end;
+                        _ ->
+                            {error, nxdomain}
+                    end;
+                _ ->
+                    {error, nxdomain}
+            end;
         {error, _} = Err ->
             Err
     catch

libs/estdlib/src/socket_dist.erl

@@ -128,11 +128,11 @@ setup(Node, Type, MyNode, LongOrShortNames, SetupTime) ->
         dist_util:net_ticker_spawn_options()
     ).
 
-do_setup(Kernel, Node, Type, MyNode, _LongOrShortNames, SetupTime) ->
+do_setup(Kernel, Node, Type, MyNode, _LongNames, SetupTime) ->
     case string:split(atom_to_list(Node), "@") of
-        [Name, Address] ->
+        [Name, Host] ->
             Timer = dist_util:start_timer(SetupTime),
-            case inet:getaddr(Address, inet) of
+            case inet:getaddr(Host, inet) of
                 {ok, Ip} ->
                     dist_util:reset_timer(Timer),
                     ErlEpmd = net_kernel:epmd_module(),
@@ -159,17 +159,17 @@ do_setup(Kernel, Node, Type, MyNode, _LongOrShortNames, SetupTime) ->
                                         Timer
                                     ),
                                     dist_util:handshake_we_started(HSData);
-                                _ ->
-                                    ?shutdown(Node)
+                                Other1 ->
+                                    ?shutdown2(Node, {unexpected, Other1})
                             end;
-                        _ ->
-                            ?shutdown(Node)
+                        Other2 ->
+                            ?shutdown2(Node, {unexpected, Other2})
                     end;
-                _ ->
-                    ?shutdown(Node)
+                Other3 ->
+                    ?shutdown2(Node, {unexpected, Other3})
             end;
-        _ ->
-            ?shutdown(Node)
+        Other4 ->
+            ?shutdown2(Node, {unexpected, Other4})
     end.
 
 close(Listen) ->