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. Signed-off-by: Paul Guyot <[email protected]>
pguyot · Jan 25, 2025 · eb5855c · eb5855c
1 parent 279c44a
commit eb5855c
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Showing 2 changed files with 34 additions and 11 deletions.
diff --git a/libs/estdlib/src/inet.erl b/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

diff --git a/libs/estdlib/src/socket_dist.erl b/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) ->