Chapril/xmpp.chapril.org-ejabberd
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Bind listener ports early and start accepting connections later

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(EJAB-1334)

It may happen that auth or rdbms client tcp connections bind a local
socket to a port number required by a configered listener. The ejabberd
applications fails to start up and needs to be restarted.

In plain C you would bind(2) the listener port and listen(2) later on.
gen_tcp:listen/2 does not allow to separate these two steps though, so
another way is not to accept connections while start up. OTOH, the
kernel will syn/ack incoming connections and receive data, leaving them
in a buffer for the ejabberd to read from. If this is unwanted, a load
balancer would need to receive data from the ejabberd server before
adding the node to its pool.

This patch binds tcp ports while initializing the ejabberd_listener
process, storing ListenSockets in an ets table. start_listeners/0 will
reuse these ports later on.
This commit is contained in:
Andreas Köhler 2010-11-02 14:43:03 +01:00 committed by Badlop
parent abf069da9e
commit 1ab92d1159
1 changed files with 69 additions and 29 deletions
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68
src/ejabberd_listener.erl
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@ -49,8 +49,31 @@ start_link() ->
init(_) ->
ets:new(listen_sockets, [named_table, public]),
bind_tcp_ports(),
{ok, {{one_for_one, 10, 1}, []}}.
bind_tcp_ports() ->
case ejabberd_config:get_local_option(listen) of
undefined ->
ignore;
Ls ->
lists:foreach(
fun({Port, Module, Opts}) ->
bind_tcp_port(Port, Module, Opts)
end, Ls)
end.
bind_tcp_port(PortIP, Module, RawOpts) ->
{Port, IPT, IPS, IPV, Proto, OptsClean} = parse_listener_portip(PortIP, RawOpts),
{_Opts, SockOpts} = prepare_opts(IPT, IPV, OptsClean),
case Proto of
udp -> ok;
_ ->
ListenSocket = listen_tcp(PortIP, Module, SockOpts, Port, IPS),
ets:insert(listen_sockets, {PortIP, ListenSocket})
end.
start_listeners() ->
case ejabberd_config:get_local_option(listen) of
undefined ->
@ -100,15 +123,7 @@ start_dependent(Port, Module, Opts) ->
init(PortIP, Module, RawOpts) ->
{Port, IPT, IPS, IPV, Proto, OptsClean} = parse_listener_portip(PortIP, RawOpts),
%% The first inet|inet6 and the last {ip, _} work,
%% so overriding those in Opts
Opts = [IPV | OptsClean] ++ [{ip, IPT}],
SockOpts = lists:filter(fun({ip, _}) -> true;
(inet6) -> true;
(inet) -> true;
({backlog, _}) -> true;
(_) -> false
end, Opts),
{Opts, SockOpts} = prepare_opts(IPT, IPV, OptsClean),
if Proto == udp ->
init_udp(PortIP, Module, Opts, SockOpts, Port, IPS);
true ->
@ -129,9 +144,24 @@ init_udp(PortIP, Module, Opts, SockOpts, Port, IPS) ->
end.
init_tcp(PortIP, Module, Opts, SockOpts, Port, IPS) ->
SockOpts2 = case erlang:system_info(otp_release) >= "R13B" of
ListenSocket = listen_tcp(PortIP, Module, SockOpts, Port, IPS),
%% Inform my parent that this port was opened succesfully
proc_lib:init_ack({ok, self()}),
%% And now start accepting connection attempts
accept(ListenSocket, Module, Opts).
listen_tcp(PortIP, Module, SockOpts, Port, IPS) ->
case ets:lookup(listen_sockets, PortIP) of
[{PortIP, ListenSocket}] ->
?INFO_MSG("Reusing listening port for ~p", [Port]),
ets:delete(listen_sockets, Port),
ListenSocket;
_ ->
SockOpts2 = try erlang:system_info(otp_release) >= "R13B" of
true -> [{send_timeout_close, true} | SockOpts];
false -> SockOpts
catch
_:_ -> []
end,
Res = gen_tcp:listen(Port, [binary,
{packet, 0},
@ -143,12 +173,10 @@ init_tcp(PortIP, Module, Opts, SockOpts, Port, IPS) ->
SockOpts2]),
case Res of
{ok, ListenSocket} ->
%% Inform my parent that this port was opened succesfully
proc_lib:init_ack({ok, self()}),
%% And now start accepting connection attempts
accept(ListenSocket, Module, Opts);
ListenSocket;
{error, Reason} ->
socket_error(Reason, PortIP, Module, SockOpts, Port, IPS)
end
end.
%% @spec (PortIP, Opts) -> {Port, IPT, IPS, IPV, OptsClean}
@ -193,6 +221,18 @@ parse_listener_portip(PortIP, Opts) ->
end,
{Port, IPT, IPS, IPV, Proto, OptsClean}.
prepare_opts(IPT, IPV, OptsClean) ->
%% The first inet|inet6 and the last {ip, _} work,
%% so overriding those in Opts
Opts = [IPV | OptsClean] ++ [{ip, IPT}],
SockOpts = lists:filter(fun({ip, _}) -> true;
(inet6) -> true;
(inet) -> true;
({backlog, _}) -> true;
(_) -> false
end, Opts),
{Opts, SockOpts}.
add_proto(Port, Opts) when is_integer(Port) ->
{Port, get_proto(Opts)};
add_proto({Port, Proto}, _Opts) when is_atom(Proto) ->