Merge branch 'hans/ssh/login_hangs/OTP-11823'

4 files changed, 42 insertions, 4 deletions

diff --git a/lib/ssh/doc/src/ssh.xml b/lib/ssh/doc/src/ssh.xml
index eaf96d0230..7fbd70c87e 100644
--- a/lib/ssh/doc/src/ssh.xml
+++ b/lib/ssh/doc/src/ssh.xml
@@ -304,6 +304,23 @@
 	      <c><![CDATA[true]]></c> if the password is valid and
 	      <c><![CDATA[false]]></c> otherwise.</p>
 	  </item>
+
+	  <tag><c><![CDATA[{negotiation_timeout, integer()}]]></c></tag>
+	  <item>
+	    <p>Max time in milliseconds for the authentication negotiation.  The default value is 2 minutes.
+	    </p>
+	  </item>
+
+	  <tag><c><![CDATA[{parallel_login, boolean()}]]></c></tag>
+	  <item>
+	    <p>If set to false (the default value), only one login is handled a time.  If set to true, an unlimited logins will be allowed simultanously. Note that this affects only the connections with authentication in progress, not the already authenticated connections.
+	    </p>
+	    <warning>
+	      <p>Do not enable parallel_logins without protecting the server by other means like a firewall. If set to true, there is no protection against dos attacs.</p>
+	    </warning>
+
+	  </item>
+
 	  <tag><c><![CDATA[{key_cb, atom()}]]></c></tag>
 	  <item>
 	    <p>Module implementing the behaviour <seealso marker="ssh_server_key_api">ssh_server_key_api</seealso>.
diff --git a/lib/ssh/src/ssh.erl b/lib/ssh/src/ssh.erl
index d50d5a0cb3..de6e8cc421 100644
--- a/lib/ssh/src/ssh.erl
+++ b/lib/ssh/src/ssh.erl
@@ -1,4 +1,4 @@
-%%
+%
 %% %CopyrightBegin%
 %%
 %% Copyright Ericsson AB 2004-2013. All Rights Reserved.
@@ -332,6 +332,12 @@ handle_option([{idle_time, _} = Opt | Rest], SocketOptions, SshOptions) ->
     handle_option(Rest, SocketOptions, [handle_ssh_option(Opt) | SshOptions]);
 handle_option([{rekey_limit, _} = Opt|Rest], SocketOptions, SshOptions) ->
     handle_option(Rest, SocketOptions, [handle_ssh_option(Opt) | SshOptions]);
+handle_option([{negotiation_timeout, _} = Opt|Rest], SocketOptions, SshOptions) ->
+    handle_option(Rest, SocketOptions, [handle_ssh_option(Opt) | SshOptions]);
+handle_option([{parallel_login, _} = Opt|Rest], SocketOptions, SshOptions) ->
+    handle_option(Rest, SocketOptions, [handle_ssh_option(Opt) | SshOptions]);
+handle_option([parallel_login|Rest], SocketOptions, SshOptions) ->
+    handle_option(Rest, SocketOptions, [handle_ssh_option({parallel_login,true}) | SshOptions]);
 handle_option([Opt | Rest], SocketOptions, SshOptions) ->
     handle_option(Rest, [handle_inet_option(Opt) | SocketOptions], SshOptions).
 
@@ -360,6 +366,10 @@ handle_ssh_option({pref_public_key_algs, Value} = Opt) when is_list(Value), leng
     end;
 handle_ssh_option({connect_timeout, Value} = Opt) when is_integer(Value); Value == infinity ->
     Opt;
+handle_ssh_option({negotiation_timeout, Value} = Opt) when is_integer(Value); Value == infinity ->
+    Opt;
+handle_ssh_option({parallel_login, Value} = Opt) when Value==true ; Value==false ->
+    Opt;
 handle_ssh_option({user, Value} = Opt) when is_list(Value) ->
     Opt;
 handle_ssh_option({dsa_pass_phrase, Value} = Opt) when is_list(Value) ->
diff --git a/lib/ssh/src/ssh_acceptor.erl b/lib/ssh/src/ssh_acceptor.erl
index 91905b2eaf..e57b07cee8 100644
--- a/lib/ssh/src/ssh_acceptor.erl
+++ b/lib/ssh/src/ssh_acceptor.erl
@@ -84,11 +84,14 @@ handle_connection(_Callback, Address, Port, Options, Socket) ->
     SystemSup = ssh_system_sup:system_supervisor(Address, Port),
     {ok, SubSysSup} = ssh_system_sup:start_subsystem(SystemSup, Options),
     ConnectionSup = ssh_subsystem_sup:connection_supervisor(SubSysSup),
+    Timeout = proplists:get_value(negotiation_timeout, 
+				  proplists:get_value(ssh_opts, Options, []),
+				  2*60*1000),
     ssh_connection_handler:start_connection(server, Socket,
 					    [{supervisors, [{system_sup, SystemSup},
 							    {subsystem_sup, SubSysSup},
 							    {connection_sup, ConnectionSup}]}
-					     | Options], infinity).
+					     | Options], Timeout).
 handle_error(timeout) ->
     ok;
 
diff --git a/lib/ssh/src/ssh_connection_handler.erl b/lib/ssh/src/ssh_connection_handler.erl
index d7fff14f92..322da50f21 100644
--- a/lib/ssh/src/ssh_connection_handler.erl
+++ b/lib/ssh/src/ssh_connection_handler.erl
@@ -110,8 +110,16 @@ start_connection(server = Role, Socket, Options, Timeout) ->
 	{ok, Pid} = ssh_connection_sup:start_child(ConnectionSup, [Role, Socket, Opts]),
 	{_, Callback, _} =  proplists:get_value(transport, Options, {tcp, gen_tcp, tcp_closed}),
 	socket_control(Socket, Pid, Callback),
-	Ref = erlang:monitor(process, Pid),
-	handshake(Pid, Ref, Timeout)
+	case proplists:get_value(parallel_login, Opts, false) of
+	    true ->
+		spawn(fun() -> 
+			      Ref = erlang:monitor(process, Pid),
+			      handshake(Pid, Ref, Timeout) 
+		      end);
+	    false ->
+		Ref = erlang:monitor(process, Pid),
+		handshake(Pid, Ref, Timeout)
+	end
     catch
 	exit:{noproc, _} ->
 	    {error, ssh_not_started};