Merge pull request #10478 from zzydxm/handshake_complete

Accept 4-arg handshake complete function in dist util

OTP-20090

Author: rickard-green

erts/doc/guides/alt_dist.md

@@ -553,13 +553,16 @@ The following `#hs_data{}` record fields need to be set unless otherwise stated:
   following signature:
 
   ```erlang
-  fun (DistCtrlr, Node, DHandle) -> void()
+  fun (DistCtrlr, Node, DHandle) -> void() |
+  fun (DistCtrlr, Node, DHandle, Context) -> void()
   ```
 
   where `DistCtrlr` is the identifier of the distribution controller, `Node` is
-  the node name of the node connected at the other end, and `DHandle` is a
-  distribution handle needed by a distribution controller process when calling
-  the following BIFs:
+  the node name of the node connected at the other end. `Context` is a map of
+  `#{creation => Creation, flags => Flags}`, and `Creation` / `Flags` are the
+  node incarnation identifier / [capability flags](erl_dist_protocol.md#dflags)
+  of the node connected at the other end. `DHandle` is a distribution handle
+  needed by a distribution controller process when calling the following BIFs:
 
   - `erlang:dist_ctrl_get_data/1`
   - `erlang:dist_ctrl_get_data_notification/1`

lib/kernel/src/dist_util.erl

@@ -497,6 +497,8 @@ convert_flags(_Undefined) ->
                 f_getopts       :: function() | 'undefined'}).
 
 connection(#hs_data{other_node = Node,
+                    other_creation = Creation,
+                    other_flags = Flags,
 		    socket = Socket,
 		    f_address = FAddress,
 		    f_setopts_pre_nodeup = FPreNodeup,
@@ -512,7 +514,11 @@ connection(#hs_data{other_node = Node,
 		ok ->
                     case HSData#hs_data.f_handshake_complete of
                         undefined -> ok;
-                        HsComplete -> HsComplete(Socket, Node, DHandle)
+                        HsComplete when is_function(HsComplete, 3) ->
+                            HsComplete(Socket, Node, DHandle);
+                        HsComplete when is_function(HsComplete, 4) ->
+                            Context = #{creation => Creation, flags => Flags},
+                            HsComplete(Socket, Node, DHandle, Context)
                     end,
 		    con_loop(#state{kernel = HSData#hs_data.kernel_pid,
                                     node = Node,