%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2003-2013. 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%
%%
%%---------------------------------------------------------------
%% Basic negotiated options with Telnet (RFC 854)
%%
%% Side A request: I WILL set option Opt.
%% Side B answer: DO go ahead, or no, DON'T set it.
%%
%% Side A request: Please DO set this option.
%% Side B answer: Ok I WILL, or no, I WON'T set it.
%%
%% "Enable option" requests may be rejected.
%% "Disable option" requests must not.
%%---------------------------------------------------------------
-module(ct_telnet_client).
-export([open/1, open/2, open/3, open/4, close/1]).
-export([send_data/2, get_data/1]).
-define(TELNET_PORT, 23).
-define(OPEN_TIMEOUT,10000).
-define(IDLE_TIMEOUT,10000).
%% telnet control characters
-define(SE, 240).
-define(NOP, 241).
-define(DM, 242).
-define(BRK, 243).
-define(IP, 244).
-define(AO, 245).
-define(AYT, 246).
-define(EC, 247).
-define(EL, 248).
-define(GA, 249).
-define(SB, 250).
-define(WILL, 251).
-define(WONT, 252).
-define(DO, 253).
-define(DONT, 254).
-define(IAC, 255).
%% telnet options
-define(BINARY, 0).
-define(ECHO, 1).
-define(SUPPRESS_GO_AHEAD, 3).
-define(TERMINAL_TYPE, 24).
-define(WINDOW_SIZE, 31).
-record(state,{get_data, keep_alive=true}).
open(Server) ->
open(Server, ?TELNET_PORT, ?OPEN_TIMEOUT, true).
open(Server, Port) ->
open(Server, Port, ?OPEN_TIMEOUT, true).
open(Server, Port, Timeout) ->
open(Server, Port, Timeout, true).
open(Server, Port, Timeout, KeepAlive) ->
Self = self(),
Pid = spawn(fun() -> init(Self, Server, Port, Timeout, KeepAlive) end),
receive
{open,Pid} ->
{ok,Pid};
{Error,Pid} ->
Error
end.
close(Pid) ->
Pid ! close.
send_data(Pid, Data) ->
Pid ! {send_data, Data++"\n"},
ok.
get_data(Pid) ->
Pid ! {get_data, self()},
receive
{data,Data} ->
{ok, Data}
end.
%%%-----------------------------------------------------------------
%%% Internal functions
init(Parent, Server, Port, Timeout, KeepAlive) ->
case gen_tcp:connect(Server, Port, [list,{packet,0}], Timeout) of
{ok,Sock} ->
dbg("Connected to: ~p (port: ~w, keep_alive: ~w)\n", [Server,Port,KeepAlive]),
send([?IAC,?DO,?SUPPRESS_GO_AHEAD], Sock),
Parent ! {open,self()},
loop(#state{get_data=10, keep_alive=KeepAlive}, Sock, []),
gen_tcp:close(Sock);
Error ->
Parent ! {Error,self()}
end.
loop(State, Sock, Acc) ->
receive
{tcp_closed,_} ->
dbg("Connection closed\n", []),
receive
{get_data,Pid} ->
Pid ! closed
after 100 ->
ok
end;
{tcp,_,Msg0} ->
dbg("tcp msg: ~p~n",[Msg0]),
Msg = check_msg(Sock,Msg0,[]),
loop(State, Sock, [Msg | Acc]);
{send_data,Data} ->
send(Data, Sock),
loop(State, Sock, Acc);
{get_data,Pid} ->
NewState =
case Acc of
[] ->
dbg("get_data nodata\n",[]),
erlang:send_after(100,self(),{get_data_delayed,Pid}),
if State#state.keep_alive == true ->
State#state{get_data=State#state.get_data - 1};
State#state.keep_alive == false ->
State
end;
_ ->
Data = lists:reverse(lists:append(Acc)),
dbg("get_data ~p\n",[Data]),
Pid ! {data,Data},
State
end,
loop(NewState, Sock, []);
{get_data_delayed,Pid} ->
NewState =
case State of
#state{keep_alive = true, get_data = 0} ->
if Acc == [] -> send([?IAC,?NOP], Sock);
true -> ok
end,
State#state{get_data=10};
_ ->
State
end,
NewAcc =
case erlang:is_process_alive(Pid) of
true ->
Data = lists:reverse(lists:append(Acc)),
dbg("get_data_delayed ~p\n",[Data]),
Pid ! {data,Data},
[];
false ->
Acc
end,
loop(NewState, Sock, NewAcc);
close ->
dbg("Closing connection\n", []),
gen_tcp:close(Sock),
ok
after wait(State#state.keep_alive,?IDLE_TIMEOUT) ->
if
Acc == [] -> send([?IAC,?NOP], Sock);
true -> ok
end,
loop(State, Sock, Acc)
end.
wait(true, Time) -> Time;
wait(false, _) -> infinity.
send(Data, Sock) ->
case Data of
[?IAC|_] = Cmd ->
cmd_dbg(Cmd);
_ ->
dbg("Sending: ~p\n", [Data])
end,
gen_tcp:send(Sock, Data),
ok.
%% [IAC,IAC] = buffer data value 255
check_msg(Sock, [?IAC,?IAC | T], Acc) ->
check_msg(Sock, T, [?IAC|Acc]);
%% respond to a command
check_msg(Sock, [?IAC | Cs], Acc) ->
case get_cmd(Cs) of
{Cmd,Cs1} ->
dbg("Got ", []),
cmd_dbg(Cmd),
respond_cmd(Cmd, Sock),
check_msg(Sock, Cs1, Acc);
error ->
Acc
end;
%% buffer a data value
check_msg(Sock, [H|T], Acc) ->
check_msg(Sock, T, [H|Acc]);
check_msg(_Sock, [], Acc) ->
Acc.
%% Positive responses (WILL and DO).
respond_cmd([?WILL,?ECHO], Sock) ->
R = [?IAC,?DO,?ECHO],
cmd_dbg(R),
gen_tcp:send(Sock, R);
respond_cmd([?DO,?ECHO], Sock) ->
R = [?IAC,?WILL,?ECHO],
cmd_dbg(R),
gen_tcp:send(Sock, R);
%% Answers from server
respond_cmd([?WILL,?SUPPRESS_GO_AHEAD], _Sock) ->
dbg("Server will suppress-go-ahead\n", []);
respond_cmd([?WONT,?SUPPRESS_GO_AHEAD], _Sock) ->
dbg("Warning! Server won't suppress-go-ahead\n", []);
respond_cmd([?DONT | _Opt], _Sock) -> % server ack?
ok;
respond_cmd([?WONT | _Opt], _Sock) -> % server ack?
ok;
%% Negative responses (WON'T and DON'T). These are default!
respond_cmd([?WILL,Opt], Sock) ->
R = [?IAC,?DONT,Opt],
cmd_dbg(R),
gen_tcp:send(Sock, R);
respond_cmd([?DO | Opt], Sock) ->
R = [?IAC,?WONT | Opt],
cmd_dbg(R),
gen_tcp:send(Sock, R);
%% Commands without options (which we ignore)
respond_cmd(?NOP, _Sock) ->
ok;
%% Unexpected messages.
respond_cmd([Cmd | Opt], _Sock) when Cmd >= 240, Cmd =< 255 ->
dbg("Received cmd: ~w. Ignored!\n", [[Cmd | Opt]]);
respond_cmd([Cmd | Opt], _Sock) ->
dbg("WARNING: Received unknown cmd: ~w. Ignored!\n", [[Cmd | Opt]]).
get_cmd([Cmd | Rest]) when Cmd == ?SB ->
get_subcmd(Rest, []);
get_cmd([Cmd | Rest]) when Cmd >= 240, Cmd =< 249 ->
{?NOP, Rest};
get_cmd([Cmd,Opt | Rest]) when Cmd >= 251, Cmd =< 254 ->
{[Cmd,Opt], Rest};
get_cmd(_Other) ->
error.
get_subcmd([?SE | Rest], Acc) ->
{[?SE | lists:reverse(Acc)], Rest};
get_subcmd([Opt | Rest], Acc) ->
get_subcmd(Rest, [Opt | Acc]).
-ifdef(debug).
dbg(_Str,_Args) ->
io:format(_Str,_Args).
cmd_dbg(_Cmd) ->
case _Cmd of
[?IAC|Cmd1] ->
cmd_dbg(Cmd1);
[Ctrl|Opts] ->
CtrlStr =
case Ctrl of
?DO -> "DO";
?DONT -> "DONT";
?WILL -> "WILL";
?WONT -> "WONT";
?NOP -> "NOP";
_ -> "CMD"
end,
Opts1 =
case Opts of
[Opt] -> Opt;
_ -> Opts
end,
io:format("~ts(~w): ~w\n", [CtrlStr,Ctrl,Opts1]);
Any ->
io:format("Unexpected in cmd_dbg:~n~w~n",[Any])
end.
-else.
dbg(_Str,_Args) ->
ok.
cmd_dbg(_Cmd) ->
ok.
-endif.
