kernel: Add -dist_listen false option

This option makes it so that the distribution no longer
listens for incoming connections. This way the node does
not need to occupy a tcp port, but it also cannot be part
of any global groups.

4 files changed, 85 insertions, 15 deletions

diff --git a/lib/kernel/src/global_group.erl b/lib/kernel/src/global_group.erl
index f5ead2a4c5..09b058af2f 100644
--- a/lib/kernel/src/global_group.erl
+++ b/lib/kernel/src/global_group.erl
@@ -1312,16 +1312,20 @@ get_own_nodes() ->
 %%% -hidden command line argument
 %%%====================================================================================
 publish_arg() ->
-    case init:get_argument(hidden) of
-	{ok,[[]]} ->
-	    hidden;
-	{ok,[["true"]]} ->
-	    hidden;
-	_ ->
-	    normal
+    case net_kernel:dist_listen() of
+        false ->
+            hidden;
+        _ ->
+            case init:get_argument(hidden) of
+                {ok,[[]]} ->
+                    hidden;
+                {ok,[["true"]]} ->
+                    hidden;
+                _ ->
+                    normal
+            end
     end.
 
-
 %%%====================================================================================
 %%% Own group publication type and nodes
 %%%====================================================================================
diff --git a/lib/kernel/src/inet6_tcp_dist.erl b/lib/kernel/src/inet6_tcp_dist.erl
index 9b6c2745d5..79f69bfa4c 100644
--- a/lib/kernel/src/inet6_tcp_dist.erl
+++ b/lib/kernel/src/inet6_tcp_dist.erl
@@ -22,7 +22,7 @@
 %% Handles the connection setup phase with other Erlang nodes.
 
 -export([listen/1, accept/1, accept_connection/5,
-         setup/5, close/1, select/1, is_node_name/1]).
+         setup/5, close/1, select/1, address/0, is_node_name/1]).
 
 -export([setopts/2, getopts/2]).
 
@@ -35,6 +35,14 @@ select(Node) ->
     inet_tcp_dist:gen_select(inet6_tcp, Node).
 
 %% ------------------------------------------------------------
+%%  Get address family
+%%  address() => #net_address{}
+%% ------------------------------------------------------------
+
+address() ->
+    inet_tcp_dist:gen_address(inet6_tcp).
+
+%% ------------------------------------------------------------
 %% Create the listen socket, i.e. the port that this erlang
 %% node is accessible through.
 %% ------------------------------------------------------------
diff --git a/lib/kernel/src/inet_tcp_dist.erl b/lib/kernel/src/inet_tcp_dist.erl
index c5a114a9ef..2ce7e4f474 100644
--- a/lib/kernel/src/inet_tcp_dist.erl
+++ b/lib/kernel/src/inet_tcp_dist.erl
@@ -22,14 +22,14 @@
 %% Handles the connection setup phase with other Erlang nodes.
 
 -export([listen/1, accept/1, accept_connection/5,
-	 setup/5, close/1, select/1, is_node_name/1]).
+	 setup/5, close/1, select/1, address/0, is_node_name/1]).
 
 %% Optional
 -export([setopts/2, getopts/2]).
 
 %% Generalized dist API
 -export([gen_listen/2, gen_accept/2, gen_accept_connection/6,
-	 gen_setup/6, gen_select/2]).
+	 gen_setup/6, gen_select/2, gen_address/1]).
 
 %% internal exports
 
@@ -64,6 +64,14 @@ gen_select(Driver, Node) ->
     end.
 
 %% ------------------------------------------------------------
+%% Get the address family that this distribution uses
+%% ------------------------------------------------------------
+address() ->
+    gen_address(inet_tcp).
+gen_address(Driver) ->
+    get_tcp_address(Driver).
+
+%% ------------------------------------------------------------
 %% Create the listen socket, i.e. the port that this erlang
 %% node is accessible through.
 %% ------------------------------------------------------------
@@ -436,9 +444,11 @@ split_node([], _, Ack)        -> [lists:reverse(Ack)].
 %% ------------------------------------------------------------
 get_tcp_address(Driver, Socket) ->
     {ok, Address} = inet:sockname(Socket),
+    NetAddr = get_tcp_address(Driver),
+    NetAddr#net_address{ address = Address }.
+get_tcp_address(Driver) ->
     {ok, Host} = inet:gethostname(),
     #net_address {
-		  address = Address,
 		  host = Host,
 		  protocol = tcp,
 		  family = Driver:family()
diff --git a/lib/kernel/src/net_kernel.erl b/lib/kernel/src/net_kernel.erl
index b857000a80..ce4966684a 100644
--- a/lib/kernel/src/net_kernel.erl
+++ b/lib/kernel/src/net_kernel.erl
@@ -68,7 +68,8 @@
 	 kernel_apply/3,
 	 longnames/0,
 	 protocol_childspecs/0,
-	 epmd_module/0]).
+	 epmd_module/0,
+         dist_listen/0]).
 
 -export([disconnect/1, passive_cnct/1]).
 -export([hidden_connect_node/1]).
@@ -693,7 +694,10 @@ terminate(no_network, State) ->
 terminate(_Reason, State) ->
     lists:foreach(
       fun(#listen {listen = Listen,module = Mod}) ->
-	      Mod:close(Listen)
+              case Listen of
+                  undefined -> ignore;
+                  _ -> Mod:close(Listen)
+              end
       end, State#state.listen),
     lists:foreach(
       fun(Node) -> ?nodedown(Node, State)
@@ -1542,6 +1546,18 @@ epmd_module() ->
     end.
 
 %%
+%% dist_listen() -> whether the erlang distribution should listen for connections
+%%
+dist_listen() ->
+    case init:get_argument(dist_listen) of
+	{ok,[[DoListen]]} ->
+	    list_to_atom(DoListen) =/= false;
+	_ ->
+	    true
+    end.
+
+
+%%
 %% Start all protocols
 %%
 
@@ -1553,8 +1569,13 @@ start_protos(Name, Node, CleanHalt) ->
 	    start_protos(Name, ["inet_tcp"], Node, CleanHalt)
     end.
 
+
+
 start_protos(Name, Ps, Node, CleanHalt) ->
-    case start_protos(Name, Ps, Node, [], CleanHalt) of
+    case case dist_listen() of
+        false -> start_protos_no_listen(Name, Ps, Node, [], CleanHalt);
+        _ -> start_protos(Name, Ps, Node, [], CleanHalt)
+         end of
 	[] ->
 	    case CleanHalt of
 		true -> halt(1);
@@ -1564,6 +1585,33 @@ start_protos(Name, Ps, Node, CleanHalt) ->
 	    {ok, Ls}
     end.
 
+start_protos_no_listen(Name, [Proto | Ps], Node, Ls, CleanHalt) ->
+    Mod = list_to_atom(Proto ++ "_dist"),
+    case set_node(Node, create_creation()) of
+        ok ->
+            auth:sync_cookie(),
+            L = #listen {
+                   listen = undefined,
+                   address = Mod:address(),
+                   accept = undefined,
+                   module = Mod },
+            start_protos_no_listen(Name, Ps, Node, [L|Ls], CleanHalt);
+        _ ->
+            S = "invalid node name: " ++ atom_to_list(Node),
+            proto_error(CleanHalt, Proto, S),
+            start_protos_no_listen(Name, Ps, Node, Ls, CleanHalt)
+    end;
+start_protos_no_listen(_Name, [], _Node, Ls, _CleanHalt) ->
+    Ls.
+
+create_creation() ->
+    try binary:decode_unsigned(crypto:strong_rand_bytes(4)) of
+        Creation ->
+            Creation
+    catch _:_ ->
+            rand:uniform((1 bsl 32)-1)
+    end.
+
 start_protos(Name, [Proto | Ps], Node, Ls, CleanHalt) ->
     Mod = list_to_atom(Proto ++ "_dist"),
     case catch Mod:listen(Name) of