Merge branch 'rickard/dist/OTP-14459' into rickard/dist/master/OTP-14459

Conflicts:
	erts/emulator/beam/bif.c
	erts/emulator/beam/dist.c
	erts/emulator/beam/dist.h
	erts/emulator/beam/erl_bif_info.c
	erts/emulator/beam/erl_node_tables.c
	erts/emulator/beam/erl_node_tables.h
	erts/emulator/beam/external.c

8 files changed, 1023 insertions, 78 deletions

diff --git a/lib/kernel/examples/Makefile b/lib/kernel/examples/Makefile
index 26ec58f571..f86e662838 100644
--- a/lib/kernel/examples/Makefile
+++ b/lib/kernel/examples/Makefile
@@ -45,7 +45,7 @@ RELSYSDIR = $(RELEASE_PATH)/lib/kernel-$(KERNEL_VSN)/examples
 # Pack and install the complete directory structure from 
 # here (CWD) and down, for all examples.
 
-EXAMPLES  = uds_dist
+EXAMPLES  = uds_dist gen_tcp_dist
 
 release_spec:
 	$(INSTALL_DIR) "$(RELSYSDIR)"
diff --git a/lib/kernel/examples/gen_tcp_dist/Makefile b/lib/kernel/examples/gen_tcp_dist/Makefile
new file mode 100644
index 0000000000..65513a1729
--- /dev/null
+++ b/lib/kernel/examples/gen_tcp_dist/Makefile
@@ -0,0 +1,20 @@
+RM=rm -f
+CP=cp
+EBIN=ebin
+ERLC=erlc
+# Works if building in open source source tree
+KERNEL_INCLUDE=$(ERL_TOP)/lib/kernel/include
+ERLCFLAGS+= -W -I$(KERNEL_INCLUDE)
+
+MODULES=gen_tcp_dist
+
+TARGET_FILES=$(MODULES:%=$(EBIN)/%.beam)
+
+opt: $(TARGET_FILES)
+
+$(EBIN)/%.beam: src/%.erl
+	$(ERLC) $(ERLCFLAGS) -o$(EBIN) $<
+
+clean:
+	$(RM) $(TARGET_FILES)
+
diff --git a/lib/kernel/examples/gen_tcp_dist/ebin/.gitignore b/lib/kernel/examples/gen_tcp_dist/ebin/.gitignore
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/lib/kernel/examples/gen_tcp_dist/ebin/.gitignore
diff --git a/lib/kernel/examples/gen_tcp_dist/src/gen_tcp_dist.erl b/lib/kernel/examples/gen_tcp_dist/src/gen_tcp_dist.erl
new file mode 100644
index 0000000000..98554ed805
--- /dev/null
+++ b/lib/kernel/examples/gen_tcp_dist/src/gen_tcp_dist.erl
@@ -0,0 +1,781 @@
+%%
+%% %CopyrightBegin%
+%% 
+%% Copyright Ericsson AB 2017. All Rights Reserved.
+%% 
+%% 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.
+%% 
+%% %CopyrightEnd%
+%%
+-module(gen_tcp_dist).
+
+%%
+%% This is an example of how to plug in an arbitrary distribution
+%% carrier for Erlang using distribution processes.
+%%
+%% This example uses gen_tcp for transportation of data, but
+%% you can use whatever underlying protocol you want as long
+%% as your implementation reliably delivers data chunks to the
+%% receiving VM in the order they were sent from the sending
+%% VM.
+%%
+%% This code is a rewrite of the lib/kernel/src/inet_tcp_dist.erl
+%% distribution impementation for TCP used by default. That
+%% implementation use distribution ports instead of distribution
+%% processes and is more efficient compared to this implementation.
+%% This since this implementation more or less gets the
+%% distribution processes in between the VM and the ports without
+%% any gain specific gain.
+%%
+
+-export([listen/1, accept/1, accept_connection/5,
+	 setup/5, close/1, select/1, is_node_name/1]).
+
+%% Optional
+-export([setopts/2, getopts/2]).
+
+%% internal exports
+
+-export([dist_cntrlr_setup/1, dist_cntrlr_input_setup/3,
+         dist_cntrlr_tick_handler/1]).
+
+-export([accept_loop/2,do_accept/6,do_setup/6]).
+
+-import(error_logger,[error_msg/2]).
+
+-include("net_address.hrl").
+
+-include("dist.hrl").
+-include("dist_util.hrl").
+
+%% ------------------------------------------------------------
+%%  Select this protocol based on node name
+%%  select(Node) => Bool
+%% ------------------------------------------------------------
+
+select(Node) ->
+    case split_node(atom_to_list(Node), $@, []) of
+	[_, Host] ->
+	    case inet:getaddr(Host, inet) of
+                {ok,_} -> true;
+                _ -> false
+            end;
+	_ -> false
+    end.
+
+%% ------------------------------------------------------------
+%% Create the listen socket, i.e. the port that this erlang
+%% node is accessible through.
+%% ------------------------------------------------------------
+
+listen(Name) ->
+    case do_listen([binary, {active, false}, {packet,2}, {reuseaddr, true}]) of
+	{ok, Socket} ->
+	    TcpAddress = get_tcp_address(Socket),
+	    {_,Port} = TcpAddress#net_address.address,
+	    ErlEpmd = net_kernel:epmd_module(),
+	    case ErlEpmd:register_node(Name, Port) of
+		{ok, Creation} ->
+		    {ok, {Socket, TcpAddress, Creation}};
+		Error ->
+		    Error
+	    end;
+	Error ->
+	    Error
+    end.
+
+do_listen(Options) ->
+    {First,Last} = case application:get_env(kernel,inet_dist_listen_min) of
+		       {ok,N} when is_integer(N) ->
+			   case application:get_env(kernel,
+						    inet_dist_listen_max) of
+			       {ok,M} when is_integer(M) ->
+				   {N,M};
+			       _ ->
+				   {N,N}
+			   end;
+		       _ ->
+			   {0,0}
+		   end,
+    do_listen(First, Last, listen_options([{backlog,128}|Options])).
+
+do_listen(First,Last,_) when First > Last ->
+    {error,eaddrinuse};
+do_listen(First,Last,Options) ->
+    case gen_tcp:listen(First, Options) of
+	{error, eaddrinuse} ->
+	    do_listen(First+1,Last,Options);
+	Other ->
+	    Other
+    end.
+
+listen_options(Opts0) ->
+    Opts1 =
+	case application:get_env(kernel, inet_dist_use_interface) of
+	    {ok, Ip} ->
+		[{ip, Ip} | Opts0];
+	    _ ->
+		Opts0
+	end,
+    case application:get_env(kernel, inet_dist_listen_options) of
+	{ok,ListenOpts} ->
+	    ListenOpts ++ Opts1;
+	_ ->
+	    Opts1
+    end.
+
+
+%% ------------------------------------------------------------
+%% Accepts new connection attempts from other Erlang nodes.
+%% ------------------------------------------------------------
+
+accept(Listen) ->
+    spawn_opt(?MODULE, accept_loop, [self(), Listen], [link, {priority, max}]).
+
+accept_loop(Kernel, Listen) ->
+    ?trace("~p~n",[{?MODULE, accept_loop, self()}]),
+    case gen_tcp:accept(Listen) of
+	{ok, Socket} ->
+            DistCtrl = spawn_dist_cntrlr(Socket), 
+            ?trace("~p~n",[{?MODULE, accept_loop, accepted, Socket, DistCtrl, self()}]),
+	    flush_controller(DistCtrl, Socket),
+	    gen_tcp:controlling_process(Socket, DistCtrl),
+	    flush_controller(DistCtrl, Socket),
+	    Kernel ! {accept,self(),DistCtrl,inet,tcp},
+            receive
+                {Kernel, controller, Pid} ->
+                    call_ctrlr(DistCtrl, {supervisor, Pid}),
+                    Pid ! {self(), controller};
+                {Kernel, unsupported_protocol} ->
+                    exit(unsupported_protocol)
+            end,
+	    accept_loop(Kernel, Listen);
+	Error ->
+	    exit(Error)
+    end.
+
+flush_controller(Pid, Socket) ->
+    receive
+	{tcp, Socket, Data} ->
+	    Pid ! {tcp, Socket, Data},
+	    flush_controller(Pid, Socket);
+	{tcp_closed, Socket} ->
+	    Pid ! {tcp_closed, Socket},
+	    flush_controller(Pid, Socket)
+    after 0 ->
+	    ok
+    end.
+
+%% ------------------------------------------------------------
+%% Accepts a new connection attempt from another Erlang node.
+%% Performs the handshake with the other side.
+%% ------------------------------------------------------------
+
+accept_connection(AcceptPid, DistCtrl, MyNode, Allowed, SetupTime) ->
+    spawn_opt(?MODULE, do_accept,
+	      [self(), AcceptPid, DistCtrl, MyNode, Allowed, SetupTime],
+	      [link, {priority, max}]).
+
+do_accept(Kernel, AcceptPid, DistCtrl, MyNode, Allowed, SetupTime) ->
+    ?trace("~p~n",[{?MODULE, do_accept, self(), MyNode}]),
+    receive
+	{AcceptPid, controller} ->
+	    Timer = dist_util:start_timer(SetupTime),
+	    case check_ip(DistCtrl) of
+		true ->
+                    HSData0 = hs_data_common(DistCtrl),
+		    HSData = HSData0#hs_data{kernel_pid = Kernel,
+                                             this_node = MyNode,
+                                             socket = DistCtrl,
+                                             timer = Timer,
+                                             this_flags = 0,
+                                             allowed = Allowed},
+		    dist_util:handshake_other_started(HSData);
+		{false,IP} ->
+		    error_msg("** Connection attempt from "
+			      "disallowed IP ~w ** ~n", [IP]),
+		    ?shutdown(no_node)
+	    end
+    end.
+
+%% we may not always want the nodelay behaviour
+%% for performance reasons
+
+nodelay() ->
+    case application:get_env(kernel, dist_nodelay) of
+	undefined ->
+	    {nodelay, true};
+	{ok, true} ->
+	    {nodelay, true};
+	{ok, false} ->
+	    {nodelay, false};
+	_ ->
+	    {nodelay, true}
+    end.
+
+%% ------------------------------------------------------------
+%% Setup a new connection to another Erlang node.
+%% Performs the handshake with the other side.
+%% ------------------------------------------------------------
+
+setup(Node, Type, MyNode, LongOrShortNames,SetupTime) ->
+    spawn_opt(?MODULE, do_setup, 
+	      [self(), Node, Type, MyNode, LongOrShortNames, SetupTime],
+	      [link, {priority, max}]).
+
+do_setup(Kernel, Node, Type, MyNode, LongOrShortNames, SetupTime) ->
+    ?trace("~p~n",[{?MODULE, do_setup, self(), Node}]),
+    [Name, Address] = splitnode(Node, LongOrShortNames),
+    case inet:getaddr(Address, inet) of
+	{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
+			gen_tcp:connect(
+			  Ip, TcpPort,
+			  connect_options([binary, {active, false}, {packet, 2}]))
+		    of
+			{ok, Socket} ->
+                            DistCtrl = spawn_dist_cntrlr(Socket), 
+                            call_ctrlr(DistCtrl, {supervisor, self()}),
+                            flush_controller(DistCtrl, Socket),
+                            gen_tcp:controlling_process(Socket, DistCtrl),
+                            flush_controller(DistCtrl, Socket),
+                            HSData0 = hs_data_common(DistCtrl),
+			    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},
+			    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;
+		_ ->
+		    ?trace("port_please (~p) "
+			   "failed.~n", [Node]),
+		    ?shutdown(Node)
+	    end;
+	_Other ->
+	    ?trace("inet_getaddr(~p) "
+		   "failed (~p).~n", [Node,_Other]),
+	    ?shutdown(Node)
+    end.
+
+connect_options(Opts) ->
+    case application:get_env(kernel, inet_dist_connect_options) of
+	{ok,ConnectOpts} ->
+	    ConnectOpts ++ Opts;
+	_ ->
+	    Opts
+    end.
+
+%%
+%% Close a socket.
+%%
+close(Listen) ->
+    gen_tcp:close(Listen).
+
+
+%% If Node is illegal terminate the connection setup!!
+splitnode(Node, LongOrShortNames) ->
+    case split_node(atom_to_list(Node), $@, []) of
+	[Name|Tail] when Tail =/= [] ->
+	    Host = lists:append(Tail),
+	    case split_node(Host, $., []) of
+		[_] when LongOrShortNames =:= longnames ->
+                    case inet:parse_address(Host) of
+                        {ok, _} ->
+                            [Name, Host];
+                        _ ->
+                            error_msg("** System running to use "
+                                      "fully qualified "
+                                      "hostnames **~n"
+                                      "** Hostname ~ts is illegal **~n",
+                                      [Host]),
+                            ?shutdown(Node)
+                    end;
+		L when length(L) > 1, LongOrShortNames =:= shortnames ->
+		    error_msg("** System NOT running to use fully qualified "
+			      "hostnames **~n"
+			      "** Hostname ~ts is illegal **~n",
+			      [Host]),
+		    ?shutdown(Node);
+		_ ->
+		    [Name, Host]
+	    end;
+	[_] ->
+	    error_msg("** Nodename ~p illegal, no '@' character **~n",
+		      [Node]),
+	    ?shutdown(Node);
+	_ ->
+	    error_msg("** Nodename ~p illegal **~n", [Node]),
+	    ?shutdown(Node)
+    end.
+
+split_node([Chr|T], Chr, Ack) -> [lists:reverse(Ack)|split_node(T, Chr, [])];
+split_node([H|T], Chr, Ack)   -> split_node(T, Chr, [H|Ack]);
+split_node([], _, Ack)        -> [lists:reverse(Ack)].
+
+%% ------------------------------------------------------------
+%% Fetch local information about a Socket.
+%% ------------------------------------------------------------
+get_tcp_address(Socket) ->
+    {ok, Address} = inet:sockname(Socket),
+    {ok, Host} = inet:gethostname(),
+    #net_address {
+		  address = Address,
+		  host = Host,
+		  protocol = tcp,
+		  family = inet
+		 }.
+
+%% ------------------------------------------------------------
+%% Do only accept new connection attempts from nodes at our
+%% own LAN, if the check_ip environment parameter is true.
+%% ------------------------------------------------------------
+check_ip(DistCtrl) ->
+    case application:get_env(check_ip) of
+	{ok, true} ->
+	    case get_ifs(DistCtrl) of
+		{ok, IFs, IP} ->
+		    check_ip(IFs, IP);
+		_ ->
+		    ?shutdown(no_node)
+	    end;
+	_ ->
+	    true
+    end.
+
+get_ifs(DistCtrl) ->
+    Socket = call_ctrlr(DistCtrl, socket),
+    case inet:peername(Socket) of
+	{ok, {IP, _}} ->
+	    case inet:getif(Socket) of
+		{ok, IFs} -> {ok, IFs, IP};
+		Error     -> Error
+	    end;
+	Error ->
+	    Error
+    end.
+
+check_ip([{OwnIP, _, Netmask}|IFs], PeerIP) ->
+    case {inet_tcp:mask(Netmask, PeerIP), inet_tcp:mask(Netmask, OwnIP)} of
+	{M, M} -> true;
+	_      -> check_ip(IFs, PeerIP)
+    end;
+check_ip([], PeerIP) ->
+    {false, PeerIP}.
+    
+is_node_name(Node) when is_atom(Node) ->
+    case split_node(atom_to_list(Node), $@, []) of
+	[_, _Host] -> true;
+	_ -> false
+    end;
+is_node_name(_Node) ->
+    false.
+
+hs_data_common(DistCtrl) ->
+    TickHandler = call_ctrlr(DistCtrl, tick_handler),
+    Socket = call_ctrlr(DistCtrl, socket),
+    #hs_data{f_send = send_fun(),
+             f_recv = recv_fun(),
+             f_setopts_pre_nodeup = setopts_pre_nodeup_fun(),
+             f_setopts_post_nodeup = setopts_post_nodeup_fun(),
+             f_getll = getll_fun(),
+             f_handshake_complete = handshake_complete_fun(),
+             f_address = address_fun(),
+             mf_setopts = setopts_fun(DistCtrl, Socket),
+             mf_getopts = getopts_fun(DistCtrl, Socket),
+             mf_getstat = getstat_fun(DistCtrl, Socket),
+             mf_tick = tick_fun(DistCtrl, TickHandler)}.
+
+%%% ------------------------------------------------------------
+%%% Distribution controller processes
+%%% ------------------------------------------------------------
+
+%%
+%% There will be five parties working together when the
+%% connection is up:
+%% - The gen_tcp socket. Providing a tcp/ip connection
+%%   to the other node.
+%% - The output handler. It will dispatch all outgoing
+%%   traffic from the VM to the gen_tcp socket. This
+%%   process is registered as distribution controller
+%%   for this channel with the VM.
+%% - The input handler. It will dispatch all incoming
+%%   traffic from the gen_tcp socket to the VM. This
+%%   process is also the socket owner and receives
+%%   incoming traffic using active-N.
+%% - The tick handler. Dispatches asynchronous tick
+%%   requests to the socket. It executes on max priority
+%%   since it is important to get ticks through to the
+%%   other end.
+%% - The channel supervisor (provided by dist_util). It
+%%   monitors traffic. Issue tick requests to the tick
+%%   handler when no outgoing traffic is seen and bring
+%%   the connection down if no incoming traffic is seen.
+%%   This process also executes on max priority.
+%%
+%%   These parties are linked togheter so should one
+%%   of them fail, all of them are terminated and the
+%%   connection is taken down.
+%%
+
+%% In order to avoid issues with lingering signal binaries
+%% we enable off-heap message queue data as well as fullsweep
+%% after 0. The fullsweeps will be cheap since we have more
+%% or less no live data.
+-define(DIST_CNTRL_COMMON_SPAWN_OPTS,
+        [{message_queue_data, off_heap},
+         {fullsweep_after, 0}]).
+
+tick_fun(DistCtrl, TickHandler) ->
+    fun (Ctrl) when Ctrl == DistCtrl ->
+            TickHandler ! tick
+    end.
+
+getstat_fun(DistCtrl, Socket) ->
+    fun (Ctrl) when Ctrl == DistCtrl ->
+            case inet:getstat(Socket, [recv_cnt, send_cnt, send_pend]) of
+                {ok, Stat} ->
+                    split_stat(Stat,0,0,0);
+                Error ->
+                    Error
+            end
+    end.
+
+split_stat([{recv_cnt, R}|Stat], _, W, P) ->
+    split_stat(Stat, R, W, P);
+split_stat([{send_cnt, W}|Stat], R, _, P) ->
+    split_stat(Stat, R, W, P);
+split_stat([{send_pend, P}|Stat], R, W, _) ->
+    split_stat(Stat, R, W, P);
+split_stat([], R, W, P) ->
+    {ok, R, W, P}.
+
+setopts_fun(DistCtrl, Socket) ->
+    fun (Ctrl, Opts) when Ctrl == DistCtrl ->
+            setopts(Socket, Opts)
+    end.
+
+getopts_fun(DistCtrl, Socket) ->
+    fun (Ctrl, Opts) when Ctrl == DistCtrl ->
+            getopts(Socket, Opts)
+    end.
+
+setopts(S, Opts) ->
+    case [Opt || {K,_}=Opt <- Opts,
+		 K =:= active orelse K =:= deliver orelse K =:= packet] of
+	[] -> inet:setopts(S,Opts);
+	Opts1 -> {error, {badopts,Opts1}}
+    end.
+
+getopts(S, Opts) ->
+    inet:getopts(S, Opts).
+
+send_fun() ->
+    fun (Ctrlr, Packet) ->
+            call_ctrlr(Ctrlr, {send, Packet})
+    end.
+
+recv_fun() ->
+    fun (Ctrlr, Length, Timeout) ->
+            case call_ctrlr(Ctrlr, {recv, Length, Timeout}) of
+                {ok, Bin} when is_binary(Bin) ->
+                    {ok, binary_to_list(Bin)};
+                Other ->
+                    Other
+            end
+    end.
+
+getll_fun() ->
+    fun (Ctrlr) ->
+            call_ctrlr(Ctrlr, getll)
+    end.
+
+address_fun() ->
+    fun (Ctrlr, Node) ->
+            case call_ctrlr(Ctrlr, {address, Node}) of
+                {error, no_node} -> %% No '@' or more than one '@' in node name.
+		    ?shutdown(no_node);
+                Res ->
+                    Res
+            end
+    end.
+
+setopts_pre_nodeup_fun() ->
+    fun (Ctrlr) ->
+            call_ctrlr(Ctrlr, pre_nodeup)
+    end.
+
+setopts_post_nodeup_fun() ->
+    fun (Ctrlr) ->
+            call_ctrlr(Ctrlr, post_nodeup)
+    end.
+
+handshake_complete_fun() ->
+    fun (Ctrlr, Node, DHandle) ->
+            call_ctrlr(Ctrlr, {handshake_complete, Node, DHandle})
+    end.
+
+call_ctrlr(Ctrlr, Msg) ->
+    Ref = erlang:monitor(process, Ctrlr),
+    Ctrlr ! {Ref, self(), Msg},
+    receive
+        {Ref, Res} ->
+            erlang:demonitor(Ref, [flush]),
+            Res;
+        {'DOWN', Ref, process, Ctrlr, Reason} ->
+            exit({dist_controller_exit, Reason})
+    end.
+
+%%
+%% The tick handler process writes a tick to the
+%% socket when it receives a 'tick' message from
+%% the connection supervisor.
+%%
+%% We are not allowed to block the connection
+%% superviser when writing a tick and we also want
+%% the tick to go through even during a heavily
+%% loaded system. gen_tcp does not have a
+%% non-blocking send operation exposed in its API
+%% and we don't want to run the distribution
+%% controller under high priority. Therefore this
+%% sparate process with max prio that dispatches
+%% ticks.
+%%
+dist_cntrlr_tick_handler(Socket) ->
+    receive
+        tick ->
+            %% May block due to busy port...
+            sock_send(Socket, "");
+        _ ->
+            ok
+    end,
+    dist_cntrlr_tick_handler(Socket).
+
+spawn_dist_cntrlr(Socket) ->
+    spawn_opt(?MODULE, dist_cntrlr_setup, [Socket],
+              [{priority, max}] ++ ?DIST_CNTRL_COMMON_SPAWN_OPTS).
+
+dist_cntrlr_setup(Socket) ->
+    TickHandler = spawn_opt(?MODULE, dist_cntrlr_tick_handler,
+                            [Socket], 
+                            [link, {priority, max}] 
+                            ++ ?DIST_CNTRL_COMMON_SPAWN_OPTS),
+    dist_cntrlr_setup_loop(Socket, TickHandler, undefined).
+
+%%
+%% During the handshake phase we loop in dist_cntrlr_setup().
+%% When the connection is up we spawn an input handler and
+%% continue as output handler.
+%%
+dist_cntrlr_setup_loop(Socket, TickHandler, Sup) ->
+    receive
+        {tcp_closed, Socket} ->
+            exit(connection_closed);
+
+        {Ref, From, {supervisor, Pid}} ->
+            Res = link(Pid),
+            From ! {Ref, Res},
+            dist_cntrlr_setup_loop(Socket, TickHandler, Pid);
+
+        {Ref, From, tick_handler} ->
+            From ! {Ref, TickHandler},
+            dist_cntrlr_setup_loop(Socket, TickHandler, Sup);
+
+        {Ref, From, socket} ->
+            From ! {Ref, Socket},
+            dist_cntrlr_setup_loop(Socket, TickHandler, Sup);
+
+        {Ref, From, {send, Packet}} ->
+            Res = gen_tcp:send(Socket, Packet),
+            From ! {Ref, Res},
+            dist_cntrlr_setup_loop(Socket, TickHandler, Sup);
+
+        {Ref, From, {recv, Length, Timeout}} ->
+            Res = gen_tcp:recv(Socket, Length, Timeout),
+            From ! {Ref, Res},
+            dist_cntrlr_setup_loop(Socket, TickHandler, Sup);
+
+        {Ref, From, getll} ->
+            From ! {Ref, {ok, self()}},
+            dist_cntrlr_setup_loop(Socket, TickHandler, Sup);
+
+        {Ref, From, {address, Node}} ->
+            Res = case inet:peername(Socket) of
+                      {ok, Address} ->
+                          case split_node(atom_to_list(Node), $@, []) of
+                              [_,Host] ->
+                                  #net_address{address=Address,host=Host,
+                                               protocol=tcp, family=inet};
+                              _ ->
+                                  {error, no_node}
+                          end
+                  end,
+            From ! {Ref, Res},
+            dist_cntrlr_setup_loop(Socket, TickHandler, Sup);
+
+        {Ref, From, pre_nodeup} ->
+            Res = inet:setopts(Socket, 
+                               [{active, false},
+                                {packet, 4},
+                                nodelay()]),
+            From ! {Ref, Res},
+            dist_cntrlr_setup_loop(Socket, TickHandler, Sup);
+
+        {Ref, From, post_nodeup} ->
+            Res = inet:setopts(Socket,
+                               [{active, false},
+                                {packet, 4},
+                                nodelay()]),
+            From ! {Ref, Res},
+            dist_cntrlr_setup_loop(Socket, TickHandler, Sup);
+
+        {Ref, From, {handshake_complete, _Node, DHandle}} ->
+            From ! {Ref, ok},
+            %% Handshake complete! Begin dispatching traffic...
+
+            %% We use separate process for dispatching input. This
+            %% is not necessary, but it enables parallel execution
+            %% of independent work loads at the same time as it
+            %% simplifies the the implementation...
+            InputHandler = spawn_opt(?MODULE, dist_cntrlr_input_setup,
+                                     [DHandle, Socket, Sup],
+                                     [link] ++ ?DIST_CNTRL_COMMON_SPAWN_OPTS),
+
+	    flush_controller(InputHandler, Socket),
+	    gen_tcp:controlling_process(Socket, InputHandler),
+	    flush_controller(InputHandler, Socket),
+
+            ok = erlang:dist_ctrl_input_handler(DHandle, InputHandler),
+
+            InputHandler ! DHandle,
+
+            %% From now on we execute on normal priority
+            process_flag(priority, normal),
+            erlang:dist_ctrl_get_data_notification(DHandle),
+            dist_cntrlr_output_loop(DHandle, Socket)
+    end.
+
+%% We use active 10 for good throughput while still
+%% maintaining back-pressure if the input controller
+%% isn't able to handle all incoming messages...
+-define(ACTIVE_INPUT, 10).
+
+dist_cntrlr_input_setup(DHandle, Socket, Sup) ->
+    link(Sup),
+    %% Ensure we don't try to put data before registerd
+    %% as input handler...
+    receive
+        DHandle ->
+            dist_cntrlr_input_loop(DHandle, Socket, 0)
+    end.
+
+dist_cntrlr_input_loop(DHandle, Socket, N) when N =< ?ACTIVE_INPUT/2 ->
+    inet:setopts(Socket, [{active, ?ACTIVE_INPUT - N}]),
+    dist_cntrlr_input_loop(DHandle, Socket, ?ACTIVE_INPUT);
+dist_cntrlr_input_loop(DHandle, Socket, N) ->
+    receive
+        {tcp_closed, Socket} ->
+            %% Connection to remote node terminated...
+            exit(connection_closed);
+
+        {tcp, Socket, Data} ->
+            %% Incoming data from remote node...
+            try erlang:dist_ctrl_put_data(DHandle, Data)
+            catch _ : _ -> death_row()
+            end,
+            dist_cntrlr_input_loop(DHandle, Socket, N-1);
+
+        _ ->
+            %% Ignore...
+            dist_cntrlr_input_loop(DHandle, Socket, N)
+    end.
+
+dist_cntrlr_send_data(DHandle, Socket) ->
+    case erlang:dist_ctrl_get_data(DHandle) of
+        none ->
+            erlang:dist_ctrl_get_data_notification(DHandle);
+        Data ->
+            sock_send(Socket, Data),
+            dist_cntrlr_send_data(DHandle, Socket)
+    end.
+
+
+dist_cntrlr_output_loop(DHandle, Socket) ->
+    receive
+        dist_data ->
+            %% Outgoing data from this node...
+            try dist_cntrlr_send_data(DHandle, Socket)
+            catch _ : _ -> death_row()
+            end,
+            dist_cntrlr_output_loop(DHandle, Socket);
+
+        {send, From, Ref, Data} ->
+            %% This is for testing only!
+            %%
+            %% Needed by some OTP distribution
+            %% test suites...
+            sock_send(Socket, Data),
+            From ! {Ref, ok},
+            dist_cntrlr_output_loop(DHandle, Socket);
+
+        _ ->
+            %% Drop garbage message...
+            dist_cntrlr_output_loop(DHandle, Socket)
+
+    end.
+
+sock_send(Socket, Data) ->
+    try gen_tcp:send(Socket, Data) of
+        ok -> ok;
+        {error, Reason} -> death_row({send_error, Reason})
+    catch
+        Type : Reason -> death_row({send_error, {Type, Reason}})
+    end.
+
+death_row() ->
+    death_row(connection_closed).
+
+death_row(normal) ->
+    %% We do not want to exit with normal
+    %% exit reason since it wont bring down
+    %% linked processes...
+    death_row();
+death_row(Reason) ->
+    %% When the connection is on its way down operations
+    %% begin to fail. We catch the failures and call
+    %% this function waiting for termination. We should
+    %% be terminated by one of our links to the other
+    %% involved parties that began bringing the
+    %% connection down. By waiting for termination we
+    %% avoid altering the exit reason for the connection
+    %% teardown. We however limit the wait to 5 seconds
+    %% and bring down the connection ourselves if not
+    %% terminated...
+    receive after 5000 -> exit(Reason) end.
diff --git a/lib/kernel/include/dist.hrl b/lib/kernel/include/dist.hrl
index d6bccdf474..db4a5eaebc 100644
--- a/lib/kernel/include/dist.hrl
+++ b/lib/kernel/include/dist.hrl
@@ -40,3 +40,33 @@
 -define(DFLAG_UTF8_ATOMS, 16#10000).
 -define(DFLAG_MAP_TAG, 16#20000).
 -define(DFLAG_BIG_CREATION, 16#40000).
+-define(DFLAG_SEND_SENDER, 16#80000).
+
+%% DFLAGs that require strict ordering or:ed together...
+-define(DFLAGS_STRICT_ORDER_DELIVERY,
+        ?DFLAG_DIST_HDR_ATOM_CACHE).
+
+
+%% Also update dflag2str() in ../src/dist_util.erl
+%% when adding flags...
+
+-define(DFLAGS_ALL,
+        (?DFLAG_PUBLISHED
+             bor ?DFLAG_ATOM_CACHE
+             bor ?DFLAG_EXTENDED_REFERENCES
+             bor ?DFLAG_DIST_MONITOR
+             bor ?DFLAG_FUN_TAGS
+             bor ?DFLAG_DIST_MONITOR_NAME
+             bor ?DFLAG_HIDDEN_ATOM_CACHE
+             bor ?DFLAG_NEW_FUN_TAGS
+             bor ?DFLAG_EXTENDED_PIDS_PORTS
+             bor ?DFLAG_EXPORT_PTR_TAG
+             bor ?DFLAG_BIT_BINARIES
+             bor ?DFLAG_NEW_FLOATS
+             bor ?DFLAG_UNICODE_IO
+             bor ?DFLAG_DIST_HDR_ATOM_CACHE
+             bor ?DFLAG_SMALL_ATOM_TAGS
+             bor ?DFLAG_UTF8_ATOMS
+             bor ?DFLAG_MAP_TAG
+             bor ?DFLAG_BIG_CREATION
+             bor ?DFLAG_SEND_SENDER)).
diff --git a/lib/kernel/include/dist_util.hrl b/lib/kernel/include/dist_util.hrl
index e3d2fe0eb6..eeb0f8dd43 100644
--- a/lib/kernel/include/dist_util.hrl
+++ b/lib/kernel/include/dist_util.hrl
@@ -29,9 +29,9 @@
 -endif.
 
 -ifdef(dist_trace).
--define(trace(Fmt,Args), io:format("~p ~p:~s",[erlang:timestamp(),node(),lists:flatten(io_lib:format(Fmt, Args))])).
+-define(trace(Fmt,Args), io:format("~p ~p:~s",[erlang:convert_time_unit(erlang:monotonic_time()-erlang:system_info(start_time), native, microsecond),node(),lists:flatten(io_lib:format(Fmt, Args))])).
 % Use the one below for config-file (early boot) connection tracing
-%-define(trace(Fmt,Args), erlang:display([erlang:now(),node(),lists:flatten(io_lib:format(Fmt, Args))])).
+%-define(trace(Fmt,Args), erlang:display([erlang:convert_time_unit(erlang:monotonic_time()-erlang:system_info(start_time), native, microsecond),node(),lists:flatten(io_lib:format(Fmt, Args))])).
 -define(trace_factor,8).
 -else.
 -define(trace(Fmt,Args), ok).
@@ -78,7 +78,13 @@
 
 	  %% New in kernel-5.1 (OTP 19.1):
 	  mf_setopts,        %% netkernel:setopts on active connection
-	  mf_getopts         %% netkernel:getopts on active connection
+	  mf_getopts,         %% netkernel:getopts on active connection
+
+          %% New in kernel-6.0 (OTP 21.0)
+          f_handshake_complete, %% Notify handshake complete
+          add_flags,         %% dflags to add
+          reject_flags,      %% dflags not to use (not all can be rejected)
+          require_flags     %% dflags that are required
 }).
 	  
 
diff --git a/lib/kernel/src/dist_util.erl b/lib/kernel/src/dist_util.erl
index b3507e5d13..08bd5946cd 100644
--- a/lib/kernel/src/dist_util.erl
+++ b/lib/kernel/src/dist_util.erl
@@ -74,6 +74,48 @@
 	       ticked = 0
 	       }).
 
+dflag2str(?DFLAG_PUBLISHED) ->
+    "PUBLISHED";
+dflag2str(?DFLAG_ATOM_CACHE) ->
+    "ATOM_CACHE";
+dflag2str(?DFLAG_EXTENDED_REFERENCES) ->
+    "EXTENDED_REFERENCES";
+dflag2str(?DFLAG_DIST_MONITOR) ->
+    "DIST_MONITOR";
+dflag2str(?DFLAG_FUN_TAGS) ->
+    "FUN_TAGS";
+dflag2str(?DFLAG_DIST_MONITOR_NAME) ->
+    "DIST_MONITOR_NAME";
+dflag2str(?DFLAG_HIDDEN_ATOM_CACHE) ->
+    "HIDDEN_ATOM_CACHE";
+dflag2str(?DFLAG_NEW_FUN_TAGS) ->
+    "NEW_FUN_TAGS";
+dflag2str(?DFLAG_EXTENDED_PIDS_PORTS) ->
+    "EXTENDED_PIDS_PORTS";
+dflag2str(?DFLAG_EXPORT_PTR_TAG) ->
+    "EXPORT_PTR_TAG";
+dflag2str(?DFLAG_BIT_BINARIES) ->
+    "BIT_BINARIES";
+dflag2str(?DFLAG_NEW_FLOATS) ->
+    "NEW_FLOATS";
+dflag2str(?DFLAG_UNICODE_IO) ->
+    "UNICODE_IO";
+dflag2str(?DFLAG_DIST_HDR_ATOM_CACHE) ->
+    "DIST_HDR_ATOM_CACHE";
+dflag2str(?DFLAG_SMALL_ATOM_TAGS) ->
+    "SMALL_ATOM_TAGS";
+dflag2str(?DFLAG_UTF8_ATOMS) ->
+    "UTF8_ATOMS";
+dflag2str(?DFLAG_MAP_TAG) ->
+    "MAP_TAG";
+dflag2str(?DFLAG_BIG_CREATION) ->
+    "BIG_CREATION";
+dflag2str(?DFLAG_SEND_SENDER) ->
+    "SEND_SENDER";
+dflag2str(_) ->
+    "UNKNOWN".
+
+
 remove_flag(Flag, Flags) ->
     case Flags band Flag of
 	0 ->
@@ -82,13 +124,13 @@ remove_flag(Flag, Flags) ->
 	    Flags - Flag
     end.
 
-adjust_flags(ThisFlags, OtherFlags) ->
+adjust_flags(ThisFlags, OtherFlags, RejectFlags) ->
     case (?DFLAG_PUBLISHED band ThisFlags) band OtherFlags of
 	0 ->
 	    {remove_flag(?DFLAG_PUBLISHED, ThisFlags),
 	     remove_flag(?DFLAG_PUBLISHED, OtherFlags)};
 	_ ->
-	    {ThisFlags, OtherFlags}
+	    {ThisFlags, OtherFlags band (bnot RejectFlags)}
     end.
 
 publish_flag(hidden, _) ->
@@ -101,36 +143,71 @@ publish_flag(_, OtherNode) ->
 	    0
     end.
 
-make_this_flags(RequestType, OtherNode) ->
-    publish_flag(RequestType, OtherNode) bor
-	%% The parenthesis below makes the compiler generate better code.
-	(?DFLAG_EXPORT_PTR_TAG bor
-	 ?DFLAG_EXTENDED_PIDS_PORTS bor
-	 ?DFLAG_EXTENDED_REFERENCES bor
-	 ?DFLAG_DIST_MONITOR bor
-	 ?DFLAG_FUN_TAGS bor
-	 ?DFLAG_DIST_MONITOR_NAME bor
-	 ?DFLAG_HIDDEN_ATOM_CACHE bor
-	 ?DFLAG_NEW_FUN_TAGS bor
-	 ?DFLAG_BIT_BINARIES bor
-	 ?DFLAG_NEW_FLOATS bor
-	 ?DFLAG_UNICODE_IO bor
-	 ?DFLAG_DIST_HDR_ATOM_CACHE bor
-	 ?DFLAG_SMALL_ATOM_TAGS bor
-	 ?DFLAG_UTF8_ATOMS bor
-	 ?DFLAG_MAP_TAG bor
-	 ?DFLAG_BIG_CREATION).
-
-handshake_other_started(#hs_data{request_type=ReqType}=HSData0) ->
+-define(DFLAGS_REMOVABLE,
+        (?DFLAG_DIST_HDR_ATOM_CACHE
+             bor ?DFLAG_HIDDEN_ATOM_CACHE
+             bor ?DFLAG_ATOM_CACHE)).
+
+-define(DFLAGS_ADDABLE,
+        (?DFLAGS_ALL
+             band (bnot (?DFLAG_PUBLISHED
+                             bor ?DFLAG_HIDDEN_ATOM_CACHE
+                             bor ?DFLAG_ATOM_CACHE)))).
+
+-define(DFLAGS_THIS_DEFAULT,
+        (?DFLAG_EXPORT_PTR_TAG
+             bor ?DFLAG_EXTENDED_PIDS_PORTS
+             bor ?DFLAG_EXTENDED_REFERENCES
+             bor ?DFLAG_DIST_MONITOR
+             bor ?DFLAG_FUN_TAGS
+             bor ?DFLAG_DIST_MONITOR_NAME
+             bor ?DFLAG_NEW_FUN_TAGS
+             bor ?DFLAG_BIT_BINARIES
+             bor ?DFLAG_NEW_FLOATS
+             bor ?DFLAG_UNICODE_IO
+             bor ?DFLAG_DIST_HDR_ATOM_CACHE
+             bor ?DFLAG_SMALL_ATOM_TAGS
+             bor ?DFLAG_UTF8_ATOMS
+             bor ?DFLAG_MAP_TAG
+             bor ?DFLAG_BIG_CREATION
+             bor ?DFLAG_SEND_SENDER)).
+
+make_this_flags(RequestType, AddFlags, RemoveFlags, OtherNode) ->
+    case RemoveFlags band (bnot ?DFLAGS_REMOVABLE) of
+        0 -> ok;
+        Rerror -> exit({"Rejecting non rejectable flags", Rerror})
+    end,
+    case AddFlags band (bnot ?DFLAGS_ADDABLE) of
+        0 -> ok;
+        Aerror -> exit({"Adding non addable flags", Aerror})
+    end,
+    Flgs0 = ?DFLAGS_THIS_DEFAULT,
+    Flgs1 = Flgs0 bor publish_flag(RequestType, OtherNode),
+    Flgs2 = Flgs1 bor AddFlags,
+    Flgs3 = Flgs2 band (bnot (?DFLAG_HIDDEN_ATOM_CACHE
+                                  bor ?DFLAG_ATOM_CACHE)),
+    Flgs3 band (bnot RemoveFlags).
+
+handshake_other_started(#hs_data{request_type=ReqType,
+                                 add_flags=AddFlgs0,
+                                 reject_flags=RejFlgs0,
+                                 require_flags=ReqFlgs0}=HSData0) ->
+    AddFlgs = convert_flags(AddFlgs0),
+    RejFlgs = convert_flags(RejFlgs0),
+    ReqFlgs = convert_flags(ReqFlgs0),
     {PreOtherFlags,Node,Version} = recv_name(HSData0),
-    PreThisFlags = make_this_flags(ReqType, Node),
+    PreThisFlags = make_this_flags(ReqType, AddFlgs, RejFlgs, Node),
     {ThisFlags, OtherFlags} = adjust_flags(PreThisFlags,
-					   PreOtherFlags),
+					   PreOtherFlags,
+                                           RejFlgs),
     HSData = HSData0#hs_data{this_flags=ThisFlags,
 			     other_flags=OtherFlags,
 			     other_version=Version,
 			     other_node=Node,
-			     other_started=true},
+			     other_started=true,
+                             add_flags=AddFlgs,
+                             reject_flags=RejFlgs,
+                             require_flags=ReqFlgs},
     check_dflags(HSData),
     is_allowed(HSData),
     ?debug({"MD5 connection from ~p (V~p)~n",
@@ -165,23 +242,18 @@ is_allowed(#hs_data{other_node = Node,
     end.
 
 %%
-%% Check that both nodes can handle the same types of extended
-%% node containers. If they can not, abort the connection.
+%% Check mandatory flags...
 %%
 check_dflags(#hs_data{other_node = Node,
                       other_flags = OtherFlags,
-                      other_started = OtherStarted} = HSData) ->
-
-    Mandatory = [{?DFLAG_EXTENDED_REFERENCES, "EXTENDED_REFERENCES"},
-                 {?DFLAG_EXTENDED_PIDS_PORTS, "EXTENDED_PIDS_PORTS"},
-                 {?DFLAG_UTF8_ATOMS, "UTF8_ATOMS"}],
-    Missing = lists:filtermap(fun({Bit, Str}) ->
-                                      case Bit band OtherFlags of
-                                          Bit -> false;
-                                          0 -> {true, Str}
-                                      end
-                              end,
-                              Mandatory),
+                      other_started = OtherStarted,
+                      require_flags = RequiredFlags} = HSData) ->
+    Mandatory = ((?DFLAG_EXTENDED_REFERENCES
+                      bor ?DFLAG_EXTENDED_PIDS_PORTS
+                      bor ?DFLAG_UTF8_ATOMS)
+                     bor RequiredFlags),
+    Missing = check_mandatory(0, ?DFLAGS_ALL, Mandatory,
+                              OtherFlags, []),
     case Missing of
         [] ->
             ok;
@@ -201,6 +273,22 @@ check_dflags(#hs_data{other_node = Node,
 	    ?shutdown2(Node, {check_dflags_failed, Missing})
     end.
 
+check_mandatory(_Bit, 0, _Mandatory, _OtherFlags, Missing) ->
+    Missing;
+check_mandatory(Bit, Left, Mandatory, OtherFlags, Missing) ->
+    DFlag = (1 bsl Bit),
+    NewLeft = Left band (bnot DFlag),
+    NewMissing = case {DFlag band Mandatory,
+                       DFlag band OtherFlags} of
+                     {DFlag, 0} ->
+                         %% Mandatory and missing...
+                         [dflag2str(DFlag) | Missing];
+                     _ ->
+                         %% Not mandatory or present...
+                         Missing
+                 end,
+    check_mandatory(Bit+1, NewLeft, Mandatory, OtherFlags, NewMissing).
+                    
 
 %% No nodedown will be sent if we fail before this process has
 %% succeeded to mark the node as pending.
@@ -314,13 +402,24 @@ flush_down() ->
     end.
 
 handshake_we_started(#hs_data{request_type=ReqType,
-			      other_node=Node}=PreHSData) ->
-    PreThisFlags = make_this_flags(ReqType, Node),
-    HSData = PreHSData#hs_data{this_flags=PreThisFlags},
+			      other_node=Node,
+                              add_flags=AddFlgs0,
+                              reject_flags=RejFlgs0,
+                              require_flags=ReqFlgs0}=PreHSData) ->
+    AddFlgs = convert_flags(AddFlgs0),
+    RejFlgs = convert_flags(RejFlgs0),
+    ReqFlgs = convert_flags(ReqFlgs0),
+    PreThisFlags = make_this_flags(ReqType, AddFlgs, RejFlgs, Node),
+    HSData = PreHSData#hs_data{this_flags = PreThisFlags,
+                               add_flags = AddFlgs,
+                               reject_flags = RejFlgs,
+                               require_flags = ReqFlgs},
     send_name(HSData),
     recv_status(HSData),
     {PreOtherFlags,ChallengeA} = recv_challenge(HSData),
-    {ThisFlags,OtherFlags} = adjust_flags(PreThisFlags, PreOtherFlags),
+    {ThisFlags,OtherFlags} = adjust_flags(PreThisFlags,
+                                          PreOtherFlags,
+                                          RejFlgs),
     NewHSData = HSData#hs_data{this_flags = ThisFlags,
 			       other_flags = OtherFlags, 
 			       other_started = false}, 
@@ -336,15 +435,16 @@ handshake_we_started(#hs_data{request_type=ReqType,
 handshake_we_started(OldHsData) when element(1,OldHsData) =:= hs_data ->
     handshake_we_started(convert_old_hsdata(OldHsData)).
 
-convert_old_hsdata({hs_data, KP, ON, TN, S, T, TF, A, OV, OF, OS, FS, FR,
-		    FS_PRE, FS_POST, FG, FA, MFT, MFG, RT}) ->
-    #hs_data{
-       kernel_pid = KP, other_node = ON, this_node = TN, socket = S, timer = T,
-       this_flags = TF, allowed = A, other_version = OV, other_flags = OF,
-       other_started = OS, f_send = FS, f_recv = FR, f_setopts_pre_nodeup = FS_PRE,
-       f_setopts_post_nodeup = FS_POST, f_getll = FG, f_address = FA,
-       mf_tick = MFT, mf_getstat = MFG, request_type = RT}.
+convert_old_hsdata(OldHsData) ->
+    OHSDL = tuple_to_list(OldHsData),
+    NoMissing = tuple_size(#hs_data{}) - tuple_size(OldHsData),
+    true = NoMissing > 0,
+    list_to_tuple(OHSDL ++ lists:duplicate(NoMissing, undefined)).
 
+convert_flags(Flags) when is_integer(Flags) ->
+    Flags;
+convert_flags(_Undefined) ->
+    0.
 
 %% --------------------------------------------------------------
 %% The connection has been established.
@@ -359,15 +459,20 @@ connection(#hs_data{other_node = Node,
     PType = publish_type(HSData#hs_data.other_flags), 
     case FPreNodeup(Socket) of
 	ok -> 
-	    do_setnode(HSData), % Succeeds or exits the process.
+	    DHandle = do_setnode(HSData), % Succeeds or exits the process.
 	    Address = FAddress(Socket,Node),
 	    mark_nodeup(HSData,Address),
 	    case FPostNodeup(Socket) of
 		ok ->
+                    case HSData#hs_data.f_handshake_complete of
+                        undefined -> ok;
+                        HsComplete -> HsComplete(Socket, Node, DHandle)
+                    end,
 		    con_loop({HSData#hs_data.kernel_pid,
 			      Node,
 			      Socket,
 			      PType,
+                              DHandle,
 			      HSData#hs_data.mf_tick,
 			      HSData#hs_data.mf_getstat,
 			      HSData#hs_data.mf_setopts,
@@ -425,18 +530,16 @@ do_setnode(#hs_data{other_node = Node, socket = Socket,
 		   [Node, Port, {publish_type(Flags), 
 				 '(', Flags, ')', 
 				 Version}]),
-	    case (catch 
-		  erlang:setnode(Node, Port, 
-				 {Flags, Version, '', ''})) of
-		{'EXIT', {system_limit, _}} ->
+            try
+                erlang:setnode(Node, Port, {Flags, Version, '', ''})
+            catch
+                error:system_limit ->
 		    error_msg("** Distribution system limit reached, "
 			      "no table space left for node ~w ** ~n",
 			      [Node]),
 		    ?shutdown(Node);
-		{'EXIT', Other} ->
-		    exit(Other);
-		_Else ->
-		    ok
+                error:Other ->
+                    exit({Other, erlang:get_stacktrace()})
 	    end;
 	_ ->
 	    error_msg("** Distribution connection error, "
@@ -468,7 +571,13 @@ mark_nodeup(#hs_data{kernel_pid = Kernel,
 	    ?shutdown(Node)
     end.
 
-con_loop({Kernel, Node, Socket, Type, MFTick, MFGetstat, MFSetOpts, MFGetOpts}=ConData,
+getstat(DHandle, _Socket, undefined) ->
+    erlang:dist_get_stat(DHandle);
+getstat(_DHandle, Socket, MFGetstat) ->
+    MFGetstat(Socket).
+
+con_loop({Kernel, Node, Socket, Type, DHandle, MFTick, MFGetstat,
+          MFSetOpts, MFGetOpts}=ConData,
 	 Tick) ->
     receive
 	{tcp_closed, Socket} ->
@@ -476,7 +585,7 @@ con_loop({Kernel, Node, Socket, Type, MFTick, MFGetstat, MFSetOpts, MFGetOpts}=C
 	{Kernel, disconnect} ->
 	    ?shutdown2(Node, disconnected);
 	{Kernel, aux_tick} ->
-	    case MFGetstat(Socket) of
+	    case getstat(DHandle, Socket, MFGetstat) of
 		{ok, _, _, PendWrite} ->
 		    send_tick(Socket, PendWrite, MFTick);
 		_ ->
@@ -484,7 +593,7 @@ con_loop({Kernel, Node, Socket, Type, MFTick, MFGetstat, MFSetOpts, MFGetOpts}=C
 	    end,
 	    con_loop(ConData, Tick);
 	{Kernel, tick} ->
-	    case send_tick(Socket, Tick, Type, 
+	    case send_tick(DHandle, Socket, Tick, Type, 
 			   MFTick, MFGetstat) of
 		{ok, NewTick} ->
 		    con_loop(ConData, NewTick);
@@ -497,7 +606,7 @@ con_loop({Kernel, Node, Socket, Type, MFTick, MFGetstat, MFSetOpts, MFGetOpts}=C
 		    ?shutdown2(Node, send_net_tick_failed)
 	    end;
 	{From, get_status} ->
-	    case MFGetstat(Socket) of
+	    case getstat(DHandle, Socket, MFGetstat) of
 		{ok, Read, Write, _} ->
 		    From ! {self(), get_status, {ok, Read, Write}},
 		    con_loop(ConData, Tick);
@@ -735,14 +844,14 @@ send_status(#hs_data{socket = Socket, other_node = Node,
 %% we haven't read anything as a hidden node only ticks when it receives 
 %% a TICK !! 
 	
-send_tick(Socket, Tick, Type, MFTick, MFGetstat) ->
+send_tick(DHandle, Socket, Tick, Type, MFTick, MFGetstat) ->
     #tick{tick = T0,
 	  read = Read,
 	  write = Write,
 	  ticked = Ticked} = Tick,
     T = T0 + 1,
     T1 = T rem 4,
-    case MFGetstat(Socket) of
+    case getstat(DHandle, Socket, MFGetstat) of
 	{ok, Read, _, _} when  Ticked =:= T ->
 	    {error, not_responding};
 	{ok, Read, W, Pend} when Type =:= hidden ->
@@ -771,11 +880,10 @@ send_tick(Socket, Tick, Type, MFTick, MFGetstat) ->
 	    Error
     end.
 
-send_tick(Socket, 0, MFTick) ->
-    MFTick(Socket);
-send_tick(_, _Pend, _) ->
-    %% Dont send tick if pending write.
-    ok.
+send_tick(_, Pend, _) when Pend /= false, Pend /= 0 ->
+    ok; %% Dont send tick if pending write.
+send_tick(Socket, _Pend, MFTick) ->
+    MFTick(Socket).
 
 %% ------------------------------------------------------------
 %% Connection setup timeout timer.
diff --git a/lib/kernel/src/net_kernel.erl b/lib/kernel/src/net_kernel.erl
index ddda396713..fb4faea420 100644
--- a/lib/kernel/src/net_kernel.erl
+++ b/lib/kernel/src/net_kernel.erl
@@ -423,8 +423,8 @@ handle_call({connect, Type, Node}, From, State) ->
 		{ok, SetupPid} ->
 		    Owners = [{SetupPid, Node} | State#state.conn_owners],
 		    {noreply,State#state{conn_owners=Owners}};
-		_  ->
-		    ?connect_failure(Node, {setup_call, failed}),
+		_Error  ->
+		    ?connect_failure(Node, {setup_call, failed, _Error}),
 		    async_reply({reply, false, State}, From)
 	    end
     end;