1 files changed, 104 insertions, 0 deletions
diff --git a/deps/rabbit/apps/rabbitmq_prelaunch/src/rabbit_prelaunch_dist.erl b/deps/rabbit/apps/rabbitmq_prelaunch/src/rabbit_prelaunch_dist.erl
new file mode 100644
index 0000000000..3d718438a7
--- /dev/null
+++ b/deps/rabbit/apps/rabbitmq_prelaunch/src/rabbit_prelaunch_dist.erl
@@ -0,0 +1,104 @@
+-module(rabbit_prelaunch_dist).
+
+-export([setup/1]).
+
+setup(#{nodename := Node, nodename_type := NameType} = Context) ->
+    rabbit_log_prelaunch:debug(""),
+    rabbit_log_prelaunch:debug("== Erlang distribution =="),
+    rabbit_log_prelaunch:debug("Rqeuested node name: ~s (type: ~s)",
+                               [Node, NameType]),
+    case node() of
+        nonode@nohost ->
+            ok = rabbit_nodes_common:ensure_epmd(),
+            ok = dist_port_range_check(Context),
+            ok = dist_port_use_check(Context),
+            ok = duplicate_node_check(Context),
+
+            ok = do_setup(Context);
+        Node ->
+            rabbit_log_prelaunch:debug(
+              "Erlang distribution already running", []),
+            ok;
+        Unexpected ->
+            throw({error, {erlang_dist_running_with_unexpected_nodename,
+                           Unexpected, Node}})
+    end,
+    ok.
+
+do_setup(#{nodename := Node, nodename_type := NameType}) ->
+    rabbit_log_prelaunch:debug("Starting Erlang distribution", []),
+    case application:get_env(kernel, net_ticktime) of
+        {ok, Ticktime} when is_integer(Ticktime) andalso Ticktime >= 1 ->
+            %% The value passed to net_kernel:start/1 is the
+            %% "minimum transition traffic interval" as defined in
+            %% net_kernel:set_net_ticktime/1.
+            MTTI = Ticktime * 1000 div 4,
+            {ok, _} = net_kernel:start([Node, NameType, MTTI]),
+            ok;
+        _ ->
+            {ok, _} = net_kernel:start([Node, NameType]),
+            ok
+    end,
+    ok.
+
+%% Check whether a node with the same name is already running
+duplicate_node_check(#{split_nodename := {NodeName, NodeHost}}) ->
+    rabbit_log_prelaunch:debug(
+      "Checking if node name ~s is already used", [NodeName]),
+    PrelaunchName = rabbit_nodes_common:make(
+                      {NodeName ++ "_prelaunch_" ++ os:getpid(),
+                       "localhost"}),
+    {ok, _} = net_kernel:start([PrelaunchName, shortnames]),
+    case rabbit_nodes_common:names(NodeHost) of
+        {ok, NamePorts}  ->
+            case proplists:is_defined(NodeName, NamePorts) of
+                true ->
+                    throw({error, {duplicate_node_name, NodeName, NodeHost}});
+                false ->
+                    ok = net_kernel:stop(),
+                    ok
+            end;
+        {error, EpmdReason} ->
+            throw({error, {epmd_error, NodeHost, EpmdReason}})
+    end.
+
+dist_port_range_check(#{erlang_dist_tcp_port := DistTcpPort}) ->
+    rabbit_log_prelaunch:debug(
+      "Checking if TCP port ~b is valid", [DistTcpPort]),
+    case DistTcpPort of
+        _ when DistTcpPort < 1 orelse DistTcpPort > 65535 ->
+            throw({error, {invalid_dist_port_range, DistTcpPort}});
+        _ ->
+            ok
+    end.
+
+dist_port_use_check(#{split_nodename := {_, NodeHost},
+                      erlang_dist_tcp_port := DistTcpPort}) ->
+    rabbit_log_prelaunch:debug(
+      "Checking if TCP port ~b is available", [DistTcpPort]),
+    dist_port_use_check_ipv4(NodeHost, DistTcpPort).
+
+dist_port_use_check_ipv4(NodeHost, Port) ->
+    case gen_tcp:listen(Port, [inet, {reuseaddr, true}]) of
+        {ok, Sock} -> gen_tcp:close(Sock);
+        {error, einval} -> dist_port_use_check_ipv6(NodeHost, Port);
+        {error, _} -> dist_port_use_check_fail(Port, NodeHost)
+    end.
+
+dist_port_use_check_ipv6(NodeHost, Port) ->
+    case gen_tcp:listen(Port, [inet6, {reuseaddr, true}]) of
+        {ok, Sock} -> gen_tcp:close(Sock);
+        {error, _} -> dist_port_use_check_fail(Port, NodeHost)
+    end.
+
+-spec dist_port_use_check_fail(non_neg_integer(), string()) ->
+                                         no_return().
+
+dist_port_use_check_fail(Port, Host) ->
+    {ok, Names} = rabbit_nodes_common:names(Host),
+    case [N || {N, P} <- Names, P =:= Port] of
+        [] ->
+            throw({error, {dist_port_already_used, Port, not_erlang, Host}});
+        [Name] ->
+            throw({error, {dist_port_already_used, Port, Name, Host}})
+    end.