summaryrefslogtreecommitdiff
path: root/lib/ssh/test/ssh_relay.erl
blob: 28000fbb97f5b8a2744e24eb723aaa64e3cd7abe (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
%%%-------------------------------------------------------------------
%%% @author Simon Cornish <simon@cali.coffee>
%%% @copyright (C) 2015, Simon Cornish
%%% @doc
%%% Provide manipulatable TCP-level relaying for testing SSH
%%% @end
%%% Created :  7 May 2015 by Simon Cornish <simon@cali.coffee>
%%%-------------------------------------------------------------------
-module(ssh_relay).

-behaviour(gen_server).

%% API
-export([start_link/4]).
-export([stop/1]).
-export([hold/4, release/2, release_next/3]).

%% gen_server callbacks
-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
	 terminate/2, code_change/3]).

-record(hold, {
	  port,
	  n,
	  tmo,
	  tref,
	  q = []
	 }).

-record(state, {
	  local_addr,
	  local_port,
	  peer_addr,
	  peer_port,
	  lpid,
	  local,
	  peer,
	  tx_hold,
	  rx_hold
	 }).

-define(ACCEPT_TMO, 200).
%%%===================================================================
%%% API
%%%===================================================================
%%--------------------------------------------------------------------
%% @doc
%% Hold N (or 'all') messages in given direction.
%% Messages will be released after the N+1th message or
%% Tmo ms or 'infinity'
%%
%% Dir is 'tx' for direction local -> peer
%%    and 'rx' for direction peer  -> local
%%
%% An Error, ealready, is returned if there is already a hold
%% in the given direction
%%
%% @spec hold(Srv, Dir, N, Tmo) -> ok | {error, Error}
%% @end
%%--------------------------------------------------------------------
hold(Srv, Dir, N, Tmo) ->
    gen_server:call(Srv, {hold, Dir, N, Tmo}).

%%--------------------------------------------------------------------
%% @doc
%% Release all held messages in given direction.
%%
%% An Error, enoent, is returned if there is no hold
%% in the given direction
%%
%% @spec release(Srv, Dir) -> ok | {error, Error}
%% @end
%%--------------------------------------------------------------------
release(Srv, Dir) ->
    gen_server:call(Srv, {release, Dir}).

%%--------------------------------------------------------------------
%% @doc
%% Release all held messages in given direction after the 
%% next message in the trigger direction
%%
%% An Error, enoent, is returned if there is no hold
%% in the given direction
%%
%% @spec release_next(Srv, Dir, TriggerDir) -> ok | {error, Error}
%% @end
%%--------------------------------------------------------------------
release_next(Srv, Dir, TriggerDir) ->
    gen_server:call(Srv, {release_next, Dir, TriggerDir}).

%%--------------------------------------------------------------------
%% @doc
%% Starts the server
%%
%% @spec start_link() -> {ok, Pid} | ignore | {error, Error}
%% @end
%%--------------------------------------------------------------------
start_link(ListenAddr, ListenPort, PeerAddr, PeerPort) ->
    gen_server:start_link(?MODULE, [ListenAddr, ListenPort, PeerAddr, PeerPort], []).

stop(Srv) ->
    unlink(Srv),
    Srv ! stop.

%%%===================================================================
%%% gen_server callbacks
%%%===================================================================

%%--------------------------------------------------------------------
%% @private
%% @doc
%% Initializes the server
%%
%% @spec init(Args) -> {ok, State} |
%%                     {ok, State, Timeout} |
%%                     ignore |
%%                     {stop, Reason}
%% @end
%%--------------------------------------------------------------------
init([ListenAddr, ListenPort, PeerAddr, PeerPort | _Options]) ->
    IfAddr = case ListenAddr of
		 {0,0,0,0} ->
		     [];
		 _ ->
		     [{ifaddr, ListenAddr}]
	     end,
    case gen_tcp:listen(ListenPort, [{reuseaddr, true}, {backlog, 1}, {active, false}, binary | IfAddr]) of
	{ok, LSock} ->
	    Parent = self(),
	    {LPid, _LMod} = spawn_monitor(fun() -> listen(Parent, LSock) end),
	    S = #state{local_addr = ListenAddr,
		       local_port = ListenPort,
		       lpid = LPid,
		       peer_addr = PeerAddr,
		       peer_port = PeerPort
		      },
	    {ok, S};
	Error ->
	    {stop, Error}
    end.

%%--------------------------------------------------------------------
%% @private
%% @doc
%% Handling call messages
%%
%% @spec handle_call(Request, From, State) ->
%%                                   {reply, Reply, State} |
%%                                   {reply, Reply, State, Timeout} |
%%                                   {noreply, State} |
%%                                   {noreply, State, Timeout} |
%%                                   {stop, Reason, Reply, State} |
%%                                   {stop, Reason, State}
%% @end
%%--------------------------------------------------------------------
handle_call({hold, Dir, N, Tmo}, _From, State) ->
    case Dir of
	tx ->
	    do_hold(#state.tx_hold, State#state.peer, N, Tmo, State);
	rx ->
	    do_hold(#state.rx_hold, State#state.local, N, Tmo, State);
	_ ->
	    {reply, {error, einval}, State}
    end;
handle_call({release, Dir}, _From, State) ->
    case Dir of
	tx ->
	    do_release(#state.tx_hold, State);
	rx ->
	    do_release(#state.rx_hold, State);
	_ ->
	    {reply, {error, einval}, State}
    end;
handle_call({release_next, _Dir, _TriggerDir}, _From, State) ->
    {reply, {error, nyi}, State};

handle_call(Request, _From, State) ->
    Reply = {unhandled, Request},
    {reply, Reply, State}.

%%--------------------------------------------------------------------
%% @private
%% @doc
%% Handling cast messages
%%
%% @spec handle_cast(Msg, State) -> {noreply, State} |
%%                                  {noreply, State, Timeout} |
%%                                  {stop, Reason, State}
%% @end
%%--------------------------------------------------------------------
handle_cast(_Msg, State) ->
    {noreply, State}.

%%--------------------------------------------------------------------
%% @private
%% @doc
%% Handling all non call/cast messages
%%
%% @spec handle_info(Info, State) -> {noreply, State} |
%%                                   {noreply, State, Timeout} |
%%                                   {stop, Reason, State}
%% @end
%%--------------------------------------------------------------------
handle_info({tcp, Local, Data}, S) when S#state.local == Local ->
    S1 = do_local(Data, S),
    {noreply, S1};

handle_info({tcp_error, Local, Error}, S) when S#state.local == Local ->
    S1 = do_local({error, Error}, S),
    {noreply, S1};

handle_info({tcp_closed, Local}, S) when S#state.local == Local ->
    S1 = do_local(closed, S),
    {noreply, S1};

handle_info({tcp, Peer, Data}, S) when S#state.peer == Peer ->
    S1 = do_peer(Data, S),
    {noreply, S1};

handle_info({tcp_error, Peer, Error}, S) when S#state.peer == Peer ->
    S1 = do_peer({error, Error}, S),
    {noreply, S1};

handle_info({tcp_closed, Peer}, S) when S#state.peer == Peer ->
    S1 = do_peer(closed, S),
    {noreply, S1};

handle_info({accept, Local}, S) ->
    S1 = do_accept(Local, S),
    {noreply, S1};

handle_info({activate, Local}, State) ->
    inet:setopts(Local, [{active, true}]),
    {noreply, State};

handle_info({release, Pos}, S) ->
    {reply, _, S1} = do_release(Pos,S),
    {noreply, S1};

handle_info(stop, State) ->
    {stop, normal, State};

handle_info({'DOWN', _Ref, _process, LPid, Reason}, S) when S#state.lpid == LPid ->
    io:format("Acceptor has finished: ~p~n", [Reason]),
    {noreply, S};

handle_info(_Info, State) ->
    io:format("Unhandled info: ~p~n", [_Info]),
    {noreply, State}.

%%--------------------------------------------------------------------
%% @private
%% @doc
%% This function is called by a gen_server when it is about to
%% terminate. It should be the opposite of Module:init/1 and do any
%% necessary cleaning up. When it returns, the gen_server terminates
%% with Reason. The return value is ignored.
%%
%% @spec terminate(Reason, State) -> void()
%% @end
%%--------------------------------------------------------------------
terminate(_Reason, _State) ->
    ok.

%%--------------------------------------------------------------------
%% @private
%% @doc
%% Convert process state when code is changed
%%
%% @spec code_change(OldVsn, State, Extra) -> {ok, NewState}
%% @end
%%--------------------------------------------------------------------
code_change(_OldVsn, State, _Extra) ->
    {ok, State}.

%%%===================================================================
%%% Internal functions
%%%===================================================================
do_hold(Pos, _Port, _N, _Tmo, S) when element(Pos, S) /= undefined ->
    {reply, {error, ealready}, S};
do_hold(Pos, Port, N, Tmo, S) ->
    TRef = if is_integer(Tmo) andalso Tmo > 0 ->
		   erlang:send_after(Tmo, self(), {release, Pos});
	      true ->
		   undefined
	   end,
    Hold = #hold{port = Port, n = N, tmo = Tmo, tref = TRef},
    {reply, ok, setelement(Pos, S, Hold)}.

do_release(HPos, S) when element(HPos, S) == undefined ->
    {reply, {error, enoent}, S};
do_release(HPos, S) ->
    #hold{port = Port, tref = TRef, q = Q} = element(HPos, S),
    lists:foreach(fun(M) -> gen_tcp:send(Port, M), erlang:yield() end, Q),
    catch erlang:cancel_timer(TRef),
    receive
	{release, HPos} -> ok
    after 0 ->
	    ok
    end,
    {reply, ok, setelement(HPos, S, undefined)}.

listen(Parent, LSock) ->
    monitor(process, Parent),
    do_listen(Parent, LSock).

do_listen(Parent, LSock) ->
    %% So annoying there is no select-like sematic for this
    case gen_tcp:accept(LSock, ?ACCEPT_TMO) of
	{ok, Sock} ->
	    Parent ! {accept, Sock},
	    gen_tcp:controlling_process(Sock, Parent),
	    Parent ! {activate, Sock},
	    do_flush(Parent, Sock),
	    gen_tcp:close(LSock);
	{error, timeout} ->
	    receive 
		DOWN when element(1, DOWN) == 'DOWN' ->
		    ok;
		stop ->
		    ok
	    after 1 ->
		    do_listen(Parent, LSock)
	    end;
	Error ->
	    gen_tcp:close(LSock),
	    exit({accept,Error})
    end.

do_flush(Parent, Sock) ->
    receive 
	{Tcp, Sock, _} = Msg when Tcp == tcp; Tcp == tcp_error ->
	    Parent ! Msg,
	    do_flush(Parent, Sock);
	{tcp_closed, Sock} = Msg ->
	    Parent ! Msg,
	    do_flush(Parent, Sock)
    after 1 ->
	    ok
    end.

do_accept(Local, S) ->
    case gen_tcp:connect(S#state.peer_addr, S#state.peer_port, [{active, true}, binary]) of
	{ok, Peer} ->
	    S#state{local = Local, peer = Peer};
	Error ->
	    exit({connect, Error})
    end.

do_local(Data, S) when is_binary(Data) ->
    TxH = S#state.tx_hold,
    if TxH == undefined ->
	    gen_tcp:send(S#state.peer, Data),
	    S;
       TxH#hold.n == 0 ->
	    lists:foreach(fun(M) -> gen_tcp:send(S#state.peer, M) end, TxH#hold.q),
	    gen_tcp:send(S#state.peer, Data),
	    catch erlang:cancel_timer(TxH#hold.tref),
	    TxP = #state.tx_hold,
	    receive
		{release, TxP} ->
		    ok
	    after 0 ->
		    ok
	    end,
	    S#state{tx_hold = undefined};
       true ->
	    Q = TxH#hold.q ++ [Data],
	    N = if is_integer(TxH#hold.n) ->
			TxH#hold.n -1;
		   true ->
			TxH#hold.n
		end,
	    S#state{tx_hold = TxH#hold{q = Q, n = N}}
    end;
do_local(Error, _S) ->
    exit({local, Error}).

do_peer(Data, S) when is_binary(Data) ->
    RxH = S#state.rx_hold,
    if RxH == undefined ->
	    gen_tcp:send(S#state.local, Data),
	    S;
       RxH#hold.n == 0 ->
	    lists:foreach(fun(M) -> gen_tcp:send(S#state.local, M) end, RxH#hold.q),
	    gen_tcp:send(S#state.local, Data),
	    catch erlang:cancel_timer(RxH#hold.tref),
	    RxP = #state.rx_hold,
	    receive
		{release, RxP} ->
		    ok
	    after 0 ->
		    ok
	    end,
	    S#state{rx_hold = undefined};
       true ->
	    Q = RxH#hold.q ++ [Data],
	    N = if is_integer(RxH#hold.n) ->
			RxH#hold.n -1;
		   true ->
			RxH#hold.n
		end,
	    S#state{rx_hold = RxH#hold{q = Q, n = N}}
    end;
do_peer(Error, _S) ->
    exit({peer, Error}).