%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2008-2013. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at http://www.erlang.org/.
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%%
%% %CopyrightEnd%
%%
%%
-module(ssh_acceptor).
%% Internal application API
-export([start_link/5,
number_of_connections/1]).
%% spawn export
-export([acceptor_init/6, acceptor_loop/6]).
-define(SLEEP_TIME, 200).
%%====================================================================
%% Internal application API
%%====================================================================
start_link(Port, Address, SockOpts, Opts, AcceptTimeout) ->
Args = [self(), Port, Address, SockOpts, Opts, AcceptTimeout],
proc_lib:start_link(?MODULE, acceptor_init, Args).
%%--------------------------------------------------------------------
%%% Internal functions
%%--------------------------------------------------------------------
acceptor_init(Parent, Port, Address, SockOpts, Opts, AcceptTimeout) ->
{_, Callback, _} =
proplists:get_value(transport, Opts, {tcp, gen_tcp, tcp_closed}),
case (catch do_socket_listen(Callback, Port, SockOpts)) of
{ok, ListenSocket} ->
proc_lib:init_ack(Parent, {ok, self()}),
acceptor_loop(Callback,
Port, Address, Opts, ListenSocket, AcceptTimeout);
Error ->
proc_lib:init_ack(Parent, Error),
error
end.
do_socket_listen(Callback, Port, Opts) ->
case Callback:listen(Port, Opts) of
{error, nxdomain} ->
Callback:listen(Port, lists:delete(inet6, Opts));
{error, enetunreach} ->
Callback:listen(Port, lists:delete(inet6, Opts));
{error, eafnosupport} ->
Callback:listen(Port, lists:delete(inet6, Opts));
Other ->
Other
end.
acceptor_loop(Callback, Port, Address, Opts, ListenSocket, AcceptTimeout) ->
case (catch Callback:accept(ListenSocket, AcceptTimeout)) of
{ok, Socket} ->
handle_connection(Callback, Address, Port, Opts, Socket),
?MODULE:acceptor_loop(Callback, Port, Address, Opts,
ListenSocket, AcceptTimeout);
{error, Reason} ->
handle_error(Reason),
?MODULE:acceptor_loop(Callback, Port, Address, Opts,
ListenSocket, AcceptTimeout);
{'EXIT', Reason} ->
handle_error(Reason),
?MODULE:acceptor_loop(Callback, Port, Address, Opts,
ListenSocket, AcceptTimeout)
end.
handle_connection(Callback, Address, Port, Options, Socket) ->
SystemSup = ssh_system_sup:system_supervisor(Address, Port),
SSHopts = proplists:get_value(ssh_opts, Options, []),
MaxSessions = proplists:get_value(max_sessions,SSHopts,infinity),
case number_of_connections(SystemSup) < MaxSessions of
true ->
{ok, SubSysSup} = ssh_system_sup:start_subsystem(SystemSup, Options),
ConnectionSup = ssh_subsystem_sup:connection_supervisor(SubSysSup),
Timeout = proplists:get_value(negotiation_timeout, SSHopts, 2*60*1000),
ssh_connection_handler:start_connection(server, Socket,
[{supervisors, [{system_sup, SystemSup},
{subsystem_sup, SubSysSup},
{connection_sup, ConnectionSup}]}
| Options], Timeout);
false ->
Callback:close(Socket),
IPstr = if is_tuple(Address) -> inet:ntoa(Address);
true -> Address
end,
Str = try io_lib:format('~s:~p',[IPstr,Port])
catch _:_ -> "port "++integer_to_list(Port)
end,
error_logger:info_report("Ssh login attempt to "++Str++" denied due to option "
"max_sessions limits to "++ io_lib:write(MaxSessions) ++
" sessions."
),
{error,max_sessions}
end.
handle_error(timeout) ->
ok;
handle_error(enfile) ->
%% Out of sockets...
timer:sleep(?SLEEP_TIME);
handle_error(emfile) ->
%% Too many open files -> Out of sockets...
timer:sleep(?SLEEP_TIME);
handle_error(closed) ->
error_logger:info_report("The ssh accept socket was closed by "
"a third party. "
"This will not have an impact on ssh "
"that will open a new accept socket and "
"go on as nothing happened. It does however "
"indicate that some other software is behaving "
"badly."),
exit(normal);
handle_error(Reason) ->
String = lists:flatten(io_lib:format("Accept error: ~p", [Reason])),
error_logger:error_report(String),
exit({accept_failed, String}).
number_of_connections(SystemSup) ->
length([X ||
{R,X,supervisor,[ssh_subsystem_sup]} <- supervisor:which_children(SystemSup),
is_pid(X),
is_reference(R)
]).
