epmd: allow alternative to dns resolving for nodename

This makes it possible to create a custom integration with a
key-value store for example. The key would then point to the
actual address. You would have to write your own epmd module
to make use of that feature.

11 files changed, 413 insertions, 108 deletions

diff --git a/erts/doc/src/Makefile b/erts/doc/src/Makefile
index 5fa8b0673a..96cc4413a9 100644
--- a/erts/doc/src/Makefile
+++ b/erts/doc/src/Makefile
@@ -74,6 +74,7 @@ XML_CHAPTER_FILES = \
 	match_spec.xml \
 	crash_dump.xml \
 	alt_dist.xml \
+	alt_disco.xml \
 	driver.xml \
 	absform.xml \
 	inet_cfg.xml \
diff --git a/erts/doc/src/alt_disco.xml b/erts/doc/src/alt_disco.xml
new file mode 100644
index 0000000000..d04221b9b3
--- /dev/null
+++ b/erts/doc/src/alt_disco.xml
@@ -0,0 +1,93 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<!DOCTYPE chapter SYSTEM "chapter.dtd">
+
+<chapter>
+  <header>
+    <copyright>
+      <year>2018</year><year>2018</year>
+      <holder>Ericsson AB. All Rights Reserved.</holder>
+    </copyright>
+    <legalnotice>
+      Licensed under the Apache License, Version 2.0 (the "License");
+      you may not use this file except in compliance with the License.
+      You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+      Unless required by applicable law or agreed to in writing, software
+      distributed under the License is distributed on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+      See the License for the specific language governing permissions and
+      limitations under the License.
+
+    </legalnotice>
+
+    <title>How to Implement an Alternative Service Discovery for Erlang Distribution
+    </title>
+    <prepared>Timmo Verlaan</prepared>
+    <responsible></responsible>
+    <docno></docno>
+    <approved></approved>
+    <checked></checked>
+    <date>2018-04-25</date>
+    <rev>PA1</rev>
+    <file>alt_disco.xml</file>
+  </header>
+  <p>
+    This section describes how to implement an alternative discovery mechanism
+    for Erlang distribution. Discovery is normally done using DNS and the
+    Erlang Port Mapper Daemon (EPMD) for port discovery.
+  </p>
+
+  <note><p>
+    Support for alternative service discovery mechanisms was added in Erlang/OTP
+    21.
+  </p></note>
+
+
+  <section>
+    <title>Introduction</title>
+    <p>To implement your own service discovery module you have to write your own
+    EPMD module. The <seealso marker="kernel:erl_epmd">EPMD module</seealso> is
+    responsible for providing the location of another node. The distribution
+    modules (<c>inet_tcp_dist</c>/<c>inet_tls_dist</c>) call the EPMD module to
+    get the IP address and port of the other node. The EPMD module that is part
+    of Erlang/OTP will resolve the hostname using DNS and uses the EPMD unix
+    process to get the port of another node. The EPMD unix process does this by
+    connecting to the other node on a well-known port, port 4369.</p>
+  </section>
+
+  <section>
+    <title>Discovery module</title>
+    <p>The discovery module needs to implement the same API as the regular
+    <seealso marker="kernel:erl_epmd">EPMD module</seealso>. However, instead of
+    communicating with EPMD you can connect to any service to find out
+    connection details of other nodes. A discovery module is enabled
+    by setting <seealso marker="erts:erl#epmd_module">-epmd_module</seealso>
+    when starting erlang. The discovery module must implement the following
+    callbacks:</p>
+
+    <taglist>
+      <tag><seealso marker="kernel:erl_epmd#start_link/0">start_link/0</seealso></tag>
+      <item>Start any processes needed by the discovery module.</item>
+      <tag><seealso marker="kernel:erl_epmd#names/1">names/1</seealso></tag>
+      <item>Return node names held by the registrar for the given host.</item>
+      <tag><seealso marker="kernel:erl_epmd#register_node/2">register_node/2</seealso></tag>
+      <item>Register the given node name with the registrar.</item>
+      <tag><seealso marker="kernel:erl_epmd#port_please/3">port_please/3</seealso></tag>
+      <item>Return the distribution port used by the given node.</item>
+    </taglist>
+
+    <p>The discovery module may implement the following callback:</p>
+
+    <taglist>
+      <tag><seealso marker="kernel:erl_epmd#address_please/3">address_please/3</seealso></tag>
+      <item><p>Return the address of the given node.
+        If not implemented, <seealso marker="kernel:inet#gethostbyname/1">
+        inet:gethostbyname/1</seealso> will be used instead</p>
+        <p>This callback may also return the port of the given node. In that case
+        <seealso marker="kernel:erl_epmd#port_please/3">port_please/3</seealso>
+        may be omitted.</p></item>
+    </taglist>
+  </section>
+</chapter>
diff --git a/erts/doc/src/part.xml b/erts/doc/src/part.xml
index d583b873a0..fc39cb30e6 100644
--- a/erts/doc/src/part.xml
+++ b/erts/doc/src/part.xml
@@ -37,6 +37,7 @@
   <xi:include href="match_spec.xml"/>
   <xi:include href="crash_dump.xml"/>
   <xi:include href="alt_dist.xml"/>
+  <xi:include href="alt_disco.xml"/>
   <xi:include href="absform.xml"/>
   <xi:include href="tty.xml"/>
   <xi:include href="driver.xml"/>
diff --git a/erts/emulator/test/distribution_SUITE.erl b/erts/emulator/test/distribution_SUITE.erl
index e40d346e10..b8b84e91a0 100644
--- a/erts/emulator/test/distribution_SUITE.erl
+++ b/erts/emulator/test/distribution_SUITE.erl
@@ -73,7 +73,7 @@
          dist_evil_parallel_receiver/0]).
 
 %% epmd_module exports
--export([start_link/0, register_node/2, register_node/3, port_please/2]).
+-export([start_link/0, register_node/2, register_node/3, port_please/2, address_please/3]).
 
 suite() ->
     [{ct_hooks,[ts_install_cth]},
@@ -2086,6 +2086,11 @@ port_please(_Name, _Ip) ->
 	    {port, Port, Version}
     end.
 
+address_please(_Name, _Address, _AddressFamily) ->
+    %% Use localhost.
+    IP = {127,0,0,1},
+    {ok, IP}.
+
 %%% Utilities
 
 timestamp() ->
diff --git a/lib/kernel/doc/src/Makefile b/lib/kernel/doc/src/Makefile
index 82869d7b15..29dc73a523 100644
--- a/lib/kernel/doc/src/Makefile
+++ b/lib/kernel/doc/src/Makefile
@@ -42,6 +42,7 @@ XML_REF3_FILES = application.xml \
 	disk_log.xml \
 	erl_boot_server.xml \
 	erl_ddll.xml \
+	erl_epmd.xml \
 	erl_prim_loader_stub.xml \
 	erlang_stub.xml \
 	error_handler.xml \
diff --git a/lib/kernel/doc/src/erl_epmd.xml b/lib/kernel/doc/src/erl_epmd.xml
new file mode 100644
index 0000000000..8b076cd2d7
--- /dev/null
+++ b/lib/kernel/doc/src/erl_epmd.xml
@@ -0,0 +1,104 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<!DOCTYPE erlref SYSTEM "erlref.dtd">
+
+<erlref>
+  <header>
+    <copyright>
+      <year>2018</year><year>2018</year>
+      <holder>Ericsson AB. All Rights Reserved.</holder>
+    </copyright>
+    <legalnotice>
+      Licensed under the Apache License, Version 2.0 (the "License");
+      you may not use this file except in compliance with the License.
+      You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+      Unless required by applicable law or agreed to in writing, software
+      distributed under the License is distributed on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+      See the License for the specific language governing permissions and
+      limitations under the License.
+
+    </legalnotice>
+
+    <title>erl_epmd</title>
+    <prepared>Timmo Verlaan</prepared>
+    <docno>1</docno>
+    <date>2018-02-19</date>
+    <rev>A</rev>
+  </header>
+  <module>erl_epmd</module>
+  <modulesummary>
+    Erlang interface towards epmd
+  </modulesummary>
+  <description>
+    <p>This module communicates with the EPMD daemon, see <seealso
+    marker="erts:epmd">epmd</seealso>. To implement your own epmd module please
+    see <seealso marker="erts:alt_disco">ERTS User's Guide: How to Implement an
+    Alternative Service Discovery for Erlang Distribution</seealso></p>
+  </description>
+
+  <funcs>
+    <func>
+      <name name="start_link" arity="0"/>
+      <fsummary>Callback for erl_distribution supervisor.</fsummary>
+      <desc>
+        <p>This function is invoked as this module is added as a child of the
+        <c>erl_distribution</c> supervisor.</p>
+      </desc>
+    </func>
+
+    <func>
+      <name name="register_node" arity="2"/>
+      <name name="register_node" arity="3"/>
+      <fsummary>Registers the node with <c>epmd</c>.</fsummary>
+      <desc>
+        <p>Registers the node with <c>epmd</c> and tells epmd what port will be
+        used for the current node. It returns a creation number. This number is
+        incremented on each register to help with identifying if a node is
+        reconnecting to epmd.</p>
+      </desc>
+    </func>
+
+    <func>
+      <name name="port_please" arity="2"/>
+      <name name="port_please" arity="3"/>
+      <fsummary>Returns the port number for a given node.</fsummary>
+      <desc>
+        <p>Requests the distribution port for the given node of an EPMD
+        instance. Together with the port it returns a distribution protocol
+        version which has been 5 since Erlang/OTP R6.</p>
+      </desc>
+    </func>
+
+    <func>
+      <name name="address_please" arity="3"/>
+      <fsummary>Returns address and port.</fsummary>
+      <desc>
+        <p>Called by the distribution module. Resolves the <c>Host</c> to an IP
+        address.</p>
+        <p>Another epmd module may return port and distribution protocol version
+        as well.</p>
+      </desc>
+    </func>
+
+    <func>
+      <name name="names" arity="1"/>
+      <fsummary>Names of Erlang nodes at a host.</fsummary>
+      <desc>
+        <p>Called by <seealso marker="net_adm"><c>net_adm:names/0</c></seealso>.
+        <c>Host</c> defaults to the localhost. Returns the names and associated
+        port numbers of the Erlang nodes that <c>epmd</c> registered at the
+        specified host. Returns <c>{error, address}</c> if <c>epmd</c> is not
+        operational.</p>
+        <p><em>Example:</em></p>
+        <pre>
+(arne@dunn)1> <input>erl_epmd:names(localhost).</input>
+{ok,[{"arne",40262}]}</pre>
+      </desc>
+    </func>
+  </funcs>
+
+</erlref>
+
diff --git a/lib/kernel/doc/src/ref_man.xml b/lib/kernel/doc/src/ref_man.xml
index c06914d23d..a633ae4832 100644
--- a/lib/kernel/doc/src/ref_man.xml
+++ b/lib/kernel/doc/src/ref_man.xml
@@ -38,6 +38,7 @@
   <xi:include href="disk_log.xml"/>
   <xi:include href="erl_boot_server.xml"/>
   <xi:include href="erl_ddll.xml"/>
+  <xi:include href="erl_epmd.xml"/>
   <xi:include href="erl_prim_loader_stub.xml"/>
   <xi:include href="erlang_stub.xml"/>
   <xi:include href="error_handler.xml"/>
diff --git a/lib/kernel/doc/src/specs.xml b/lib/kernel/doc/src/specs.xml
index bcc422930e..b8c25ca53b 100644
--- a/lib/kernel/doc/src/specs.xml
+++ b/lib/kernel/doc/src/specs.xml
@@ -6,6 +6,7 @@
   <xi:include href="../specs/specs_disk_log.xml"/>
   <xi:include href="../specs/specs_erl_boot_server.xml"/>
   <xi:include href="../specs/specs_erl_ddll.xml"/>
+  <xi:include href="../specs/specs_erl_epmd.xml"/>
   <xi:include href="../specs/specs_erl_prim_loader_stub.xml"/>
   <xi:include href="../specs/specs_erlang_stub.xml"/>
   <xi:include href="../specs/specs_error_handler.xml"/>
diff --git a/lib/kernel/src/erl_epmd.erl b/lib/kernel/src/erl_epmd.erl
index f96bc88913..9a0939972d 100644
--- a/lib/kernel/src/erl_epmd.erl
+++ b/lib/kernel/src/erl_epmd.erl
@@ -29,10 +29,20 @@
 -define(port_please_failure2(Term), noop).
 -endif.
 
+-ifndef(erlang_daemon_port).
+-define(erlang_daemon_port, 4369).
+-endif.
+-ifndef(epmd_dist_high).
+-define(epmd_dist_high, 4370).
+-endif.
+-ifndef(epmd_dist_low).
+-define(epmd_dist_low, 4370).
+-endif.
+
 %% External exports
 -export([start/0, start_link/0, stop/0, port_please/2, 
 	 port_please/3, names/0, names/1,
-	 register_node/2, register_node/3, open/0, open/1, open/2]).
+	 register_node/2, register_node/3, address_please/3, open/0, open/1, open/2]).
 
 %% gen_server callbacks
 -export([init/1, handle_call/3, handle_cast/2, handle_info/2, 
@@ -53,7 +63,7 @@
 start() ->
     gen_server:start({local, erl_epmd}, ?MODULE, [], []).
 
-
+-spec start_link() -> {ok, pid()} | ignore | {error,term()}.
 start_link() ->
     gen_server:start_link({local, erl_epmd}, ?MODULE, [], []).
 
@@ -66,9 +76,22 @@ stop() ->
 %% return {port, P, Version} | noport
 %%
 
+-spec port_please(Name, Host) -> {ok, Port, Version} | noport when
+	  Name :: string(),
+	  Host :: inet:ip_address(),
+	  Port :: non_neg_integer(),
+	  Version :: non_neg_integer().
+
 port_please(Node, Host) ->
   port_please(Node, Host, infinity).
 
+-spec port_please(Name, Host, Timeout) -> {ok, Port, Version} | noport when
+	  Name :: string(),
+	  Host :: inet:ip_address(),
+	  Timeout :: non_neg_integer() | infinity,
+	  Port :: non_neg_integer(),
+	  Version :: non_neg_integer().
+
 port_please(Node,HostName, Timeout) when is_atom(HostName) ->
   port_please1(Node,atom_to_list(HostName), Timeout);
 port_please(Node,HostName, Timeout) when is_list(HostName) ->
@@ -92,10 +115,21 @@ port_please1(Node,HostName, Timeout) ->
       Else
   end.
 
+-spec names() -> {ok, [{Name, Port}]} | {error, Reason} when
+	  Name :: string(),
+	  Port :: non_neg_integer(),
+	  Reason :: address | file:posix().
+
 names() ->
     {ok, H} = inet:gethostname(),
     names(H).
 
+-spec names(Host) -> {ok, [{Name, Port}]} | {error, Reason} when
+      Host :: atom() | string() | inet:ip_address(),
+      Name :: string(),
+      Port :: non_neg_integer(),
+      Reason :: address | file:posix().
+
 names(HostName) when is_atom(HostName); is_list(HostName) ->
   case inet:gethostbyname(HostName) of
     {ok,{hostent, _Name, _ , _Af, _Size, [EpmdAddr | _]}} ->
@@ -106,9 +140,22 @@ names(HostName) when is_atom(HostName); is_list(HostName) ->
 names(EpmdAddr) ->
   get_names(EpmdAddr).
 
+-spec register_node(Name, Port) -> Result when
+	  Name :: string(),
+	  Port :: non_neg_integer(),
+	  Creation :: non_neg_integer(),
+	  Result :: {ok, Creation} | {error, already_registered} | term().
 
 register_node(Name, PortNo) ->
-    register_node(Name, PortNo, inet).
+	register_node(Name, PortNo, inet).
+
+-spec register_node(Name, Port, Driver) -> Result when
+	  Name :: string(),
+	  Port :: non_neg_integer(),
+	  Driver :: inet_tcp | inet6_tcp | inet | inet6,
+	  Creation :: non_neg_integer(),
+	  Result :: {ok, Creation} | {error, already_registered} | term().
+
 register_node(Name, PortNo, inet_tcp) ->
     register_node(Name, PortNo, inet);
 register_node(Name, PortNo, inet6_tcp) ->
@@ -116,6 +163,17 @@ register_node(Name, PortNo, inet6_tcp) ->
 register_node(Name, PortNo, Family) ->
     gen_server:call(erl_epmd, {register, Name, PortNo, Family}, infinity).
 
+-spec address_please(Name, Host, AddressFamily) -> Success | {error, term()} when
+	  Name :: string(),
+	  Host :: string() | inet:ip_address(),
+	  AddressFamily :: inet | inet6,
+	  Port :: non_neg_integer(),
+	  Version :: non_neg_integer(),
+	  Success :: {ok, inet:ip_address()} | {ok, inet:ip_address(), Port, Version}.
+
+address_please(_Name, Host, AddressFamily) ->
+	inet:getaddr(Host, AddressFamily).
+
 %%%----------------------------------------------------------------------
 %%% Callback functions from gen_server
 %%%----------------------------------------------------------------------
diff --git a/lib/kernel/src/inet_tcp_dist.erl b/lib/kernel/src/inet_tcp_dist.erl
index e3fdb1bb22..b4b50899f7 100644
--- a/lib/kernel/src/inet_tcp_dist.erl
+++ b/lib/kernel/src/inet_tcp_dist.erl
@@ -283,73 +283,22 @@ do_setup(Driver, Kernel, Node, Type, MyNode, LongOrShortNames, SetupTime) ->
     ?trace("~p~n",[{inet_tcp_dist,self(),setup,Node}]),
     [Name, Address] = splitnode(Driver, Node, LongOrShortNames),
     AddressFamily = Driver:family(),
-    case inet:getaddr(Address, AddressFamily) of
+    ErlEpmd = net_kernel:epmd_module(),
+    {ARMod, ARFun} = get_address_resolver(ErlEpmd),
+    Timer = dist_util:start_timer(SetupTime),
+    case ARMod:ARFun(Name, Address, AddressFamily) of
+	{ok, Ip, TcpPort, Version} ->
+		?trace("address_please(~p) -> version ~p~n",
+			[Node,Version]),
+		do_setup_connect(Driver, Kernel, Node, Address, AddressFamily,
+		                 Ip, TcpPort, Version, Type, MyNode, Timer);
 	{ok, Ip} ->
-	    Timer = dist_util:start_timer(SetupTime),
-	    ErlEpmd = net_kernel:epmd_module(),
 	    case ErlEpmd:port_please(Name, Ip) of
 		{port, TcpPort, Version} ->
 		    ?trace("port_please(~p) -> version ~p~n", 
 			   [Node,Version]),
-		    dist_util:reset_timer(Timer),
-		    case
-			Driver:connect(
-			  Ip, TcpPort,
-			  connect_options([{active, false}, {packet, 2}]))
-		    of
-			{ok, Socket} ->
-			    HSData = #hs_data{
-			      kernel_pid = Kernel,
-			      other_node = Node,
-			      this_node = MyNode,
-			      socket = Socket,
-			      timer = Timer,
-			      this_flags = 0,
-			      other_version = Version,
-			      f_send = fun Driver:send/2,
-			      f_recv = fun Driver:recv/3,
-			      f_setopts_pre_nodeup = 
-			      fun(S) ->
-				      inet:setopts
-					(S, 
-					 [{active, false},
-					  {packet, 4},
-					  nodelay()])
-			      end,
-			      f_setopts_post_nodeup = 
-			      fun(S) ->
-				      inet:setopts
-					(S, 
-					 [{active, true},
-					  {deliver, port},
-					  {packet, 4},
-					  nodelay()])
-			      end,
-
-			      f_getll = fun inet:getll/1,
-			      f_address = 
-			      fun(_,_) ->
-				      #net_address{
-				   address = {Ip,TcpPort},
-				   host = Address,
-				   protocol = tcp,
-				   family = AddressFamily}
-			      end,
-			      mf_tick = fun(S) -> ?MODULE:tick(Driver, S) end,
-			      mf_getstat = fun ?MODULE:getstat/1,
-			      request_type = Type,
-			      mf_setopts = fun ?MODULE:setopts/2,
-			      mf_getopts = fun ?MODULE:getopts/2
-			     },
-			    dist_util:handshake_we_started(HSData);
-			_ ->
-			    %% Other Node may have closed since 
-			    %% port_please !
-			    ?trace("other node (~p) "
-				   "closed since port_please.~n", 
-				   [Node]),
-			    ?shutdown(Node)
-		    end;
+			do_setup_connect(Driver, Kernel, Node, Address, AddressFamily,
+			                 Ip, TcpPort, Version, Type, MyNode, Timer);
 		_ ->
 		    ?trace("port_please (~p) "
 			   "failed.~n", [Node]),
@@ -361,6 +310,71 @@ do_setup(Driver, Kernel, Node, Type, MyNode, LongOrShortNames, SetupTime) ->
 	    ?shutdown(Node)
     end.
 
+%%
+%% Actual setup of connection
+%%
+do_setup_connect(Driver, Kernel, Node, Address, AddressFamily,
+                 Ip, TcpPort, Version, Type, MyNode, Timer) ->
+	dist_util:reset_timer(Timer),
+	case
+	Driver:connect(
+	  Ip, TcpPort,
+	  connect_options([{active, false}, {packet, 2}]))
+	of
+	{ok, Socket} ->
+		HSData = #hs_data{
+		  kernel_pid = Kernel,
+		  other_node = Node,
+		  this_node = MyNode,
+		  socket = Socket,
+		  timer = Timer,
+		  this_flags = 0,
+		  other_version = Version,
+		  f_send = fun Driver:send/2,
+		  f_recv = fun Driver:recv/3,
+		  f_setopts_pre_nodeup =
+		  fun(S) ->
+			  inet:setopts
+			(S,
+			 [{active, false},
+			  {packet, 4},
+			  nodelay()])
+		  end,
+		  f_setopts_post_nodeup =
+		  fun(S) ->
+			  inet:setopts
+			(S,
+			 [{active, true},
+			  {deliver, port},
+			  {packet, 4},
+			  nodelay()])
+		  end,
+
+		  f_getll = fun inet:getll/1,
+		  f_address =
+		  fun(_,_) ->
+			  #net_address{
+		   address = {Ip,TcpPort},
+		   host = Address,
+		   protocol = tcp,
+		   family = AddressFamily}
+		  end,
+		  mf_tick = fun(S) -> ?MODULE:tick(Driver, S) end,
+		  mf_getstat = fun ?MODULE:getstat/1,
+		  request_type = Type,
+		  mf_setopts = fun ?MODULE:setopts/2,
+		  mf_getopts = fun ?MODULE:getopts/2
+		 },
+		dist_util:handshake_we_started(HSData);
+	_ ->
+		%% Other Node may have closed since
+		%% discovery !
+		?trace("other node (~p) "
+		   "closed since discovery (port_please).~n",
+		   [Node]),
+		?shutdown(Node)
+	end.
+
 connect_options(Opts) ->
     case application:get_env(kernel, inet_dist_connect_options) of
 	{ok,ConnectOpts} ->
@@ -430,6 +444,16 @@ get_tcp_address(Driver, Socket) ->
 		 }.
 
 %% ------------------------------------------------------------
+%% Determine if EPMD module supports address resolving. Default
+%% is to use inet:getaddr/2.
+%% ------------------------------------------------------------
+get_address_resolver(EpmdModule) ->
+    case erlang:function_exported(EpmdModule, address_please, 3) of
+        true -> {EpmdModule, address_please};
+        _    -> {inet, getaddr}
+    end.
+
+%% ------------------------------------------------------------
 %% Do only accept new connection attempts from nodes at our
 %% own LAN, if the check_ip environment parameter is true.
 %% ------------------------------------------------------------
diff --git a/lib/ssl/src/inet_tls_dist.erl b/lib/ssl/src/inet_tls_dist.erl
index 3e9828a2fe..d45f209838 100644
--- a/lib/ssl/src/inet_tls_dist.erl
+++ b/lib/ssl/src/inet_tls_dist.erl
@@ -518,51 +518,16 @@ gen_setup(Driver, Node, Type, MyNode, LongOrShortNames, SetupTime) ->
 
 do_setup(Driver, Kernel, Node, Type, MyNode, LongOrShortNames, SetupTime) ->
     {Name, Address} = split_node(Driver, Node, LongOrShortNames),
-    case Driver:getaddr(Address) of
+    ErlEpmd = net_kernel:epmd_module(),
+    {ARMod, ARFun} = get_address_resolver(ErlEpmd, Driver),
+    Timer = trace(dist_util:start_timer(SetupTime)),
+    case ARMod:ARFun(Address) of
+    {ok, Ip, TcpPort, Version} ->
+        do_setup_connect(Driver, Kernel, Node, Address, Ip, TcpPort, Version, Type, MyNode, Timer);
 	{ok, Ip} ->
-            Timer = trace(dist_util:start_timer(SetupTime)),
-	    ErlEpmd = net_kernel:epmd_module(),
 	    case ErlEpmd:port_please(Name, Ip) of
 		{port, TcpPort, Version} ->
-                    Opts =
-                        trace(
-                          connect_options(
-                            %%
-                            %% Use verify_server/3 to verify that
-                            %% the server's certificate is for Node
-                            %%
-                            setup_verify_server(
-                              get_ssl_options(client), Node))),
-		    dist_util:reset_timer(Timer),
-                    case ssl:connect(
-                           Address, TcpPort,
-                           [binary, {active, false}, {packet, 4},
-                            Driver:family(), nodelay()] ++ Opts,
-                           net_kernel:connecttime()) of
-			{ok, #sslsocket{pid = DistCtrl} = SslSocket} ->
-                            _ = monitor_pid(DistCtrl),
-                            ok = ssl:controlling_process(SslSocket, self()),
-                            HSData0 = hs_data_common(SslSocket),
-			    HSData =
-                                HSData0#hs_data{
-                                  kernel_pid = Kernel,
-                                  other_node = Node,
-                                  this_node = MyNode,
-                                  socket = DistCtrl,
-                                  timer = Timer,
-                                  this_flags = 0,
-                                  other_version = Version,
-                                  request_type = Type},
-                            link(DistCtrl),
-			    dist_util:handshake_we_started(trace(HSData));
-			Other ->
-			    %% Other Node may have closed since 
-			    %% port_please !
-			    ?shutdown2(
-                               Node,
-                               trace(
-                                 {ssl_connect_failed, Ip, TcpPort, Other}))
-		    end;
+                do_setup_connect(Driver, Kernel, Node, Address, Ip, TcpPort, Version, Type, MyNode, Timer);
 		Other ->
 		    ?shutdown2(
                        Node,
@@ -575,6 +540,47 @@ do_setup(Driver, Kernel, Node, Type, MyNode, LongOrShortNames, SetupTime) ->
                trace({getaddr_failed, Driver, Address, Other}))
     end.
 
+do_setup_connect(Driver, Kernel, Node, Address, Ip, TcpPort, Version, Type, MyNode, Timer) ->
+    Opts =
+        trace(
+            connect_options(
+            %%
+            %% Use verify_server/3 to verify that
+            %% the server's certificate is for Node
+            %%
+            setup_verify_server(
+                get_ssl_options(client), Node))),
+    dist_util:reset_timer(Timer),
+    case ssl:connect(
+        Address, TcpPort,
+        [binary, {active, false}, {packet, 4},
+            Driver:family(), nodelay()] ++ Opts,
+        net_kernel:connecttime()) of
+    {ok, #sslsocket{pid = DistCtrl} = SslSocket} ->
+            _ = monitor_pid(DistCtrl),
+            ok = ssl:controlling_process(SslSocket, self()),
+            HSData0 = hs_data_common(SslSocket),
+        HSData =
+                HSData0#hs_data{
+                kernel_pid = Kernel,
+                other_node = Node,
+                this_node = MyNode,
+                socket = DistCtrl,
+                timer = Timer,
+                this_flags = 0,
+                other_version = Version,
+                request_type = Type},
+            link(DistCtrl),
+    dist_util:handshake_we_started(trace(HSData));
+    Other ->
+    %% Other Node may have closed since
+    %% port_please !
+    ?shutdown2(
+            Node,
+            trace(
+                {ssl_connect_failed, Ip, TcpPort, Other}))
+    end.
+
 close(Socket) ->
     gen_close(inet, Socket).
 
@@ -644,6 +650,16 @@ verify_server(PeerCert, valid_peer, {CertNodesFun,Node} = S) ->
 
 
 %% ------------------------------------------------------------
+%% Determine if EPMD module supports address resolving. Default
+%% is to use inet_tcp:getaddr/2.
+%% ------------------------------------------------------------
+get_address_resolver(EpmdModule, Driver) ->
+    case erlang:function_exported(EpmdModule, address_please, 3) of
+        true -> {EpmdModule, address_please};
+        _    -> {Driver, getaddr}
+    end.
+
+%% ------------------------------------------------------------
 %% Do only accept new connection attempts from nodes at our
 %% own LAN, if the check_ip environment parameter is true.
 %% ------------------------------------------------------------