aboutsummaryrefslogtreecommitdiffstats
path: root/src/gun_http.erl
blob: 57f72c7617af364cc7aa5c008e9bc464d455161f (plain) (blame)
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
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
%% Copyright (c) 2014-2018, Loïc Hoguin <[email protected]>
%%
%% Permission to use, copy, modify, and/or distribute this software for any
%% purpose with or without fee is hereby granted, provided that the above
%% copyright notice and this permission notice appear in all copies.
%%
%% THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
%% WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
%% MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
%% ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
%% WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
%% ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
%% OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

-module(gun_http).

-export([check_options/1]).
-export([name/0]).
-export([init/4]).
-export([handle/2]).
-export([close/2]).
-export([keepalive/1]).
-export([request/8]).
-export([request/9]).
-export([data/5]).
-export([connect/5]).
-export([cancel/3]).
-export([down/1]).
-export([ws_upgrade/7]).

-type io() :: head | {body, non_neg_integer()} | body_close | body_chunked | body_trailer.

%% @todo Make that a record.
-type connect_info() :: {connect, reference(), gun:connect_destination()}.

%% @todo Make that a record.
-type websocket_info() :: {websocket, reference(), binary(), [binary()], gun:ws_opts()}. %% key, extensions, options

-record(stream, {
	ref :: reference() | connect_info() | websocket_info(),
	reply_to :: pid(),
	method :: binary(),
	is_alive :: boolean(),
	handler_state :: undefined | gun_content_handler:state()
}).

-record(http_state, {
	owner :: pid(),
	socket :: inet:socket() | ssl:sslsocket(),
	transport :: module(),
	version = 'HTTP/1.1' :: cow_http:version(),
	content_handlers :: gun_content_handler:opt(),
	connection = keepalive :: keepalive | close,
	buffer = <<>> :: binary(),
	streams = [] :: [#stream{}],
	in = head :: io(),
	in_state = {0, 0} :: {non_neg_integer(), non_neg_integer()},
	out = head :: io(),
	transform_header_name :: fun((binary()) -> binary())
}).

check_options(Opts) ->
	do_check_options(maps:to_list(Opts)).

do_check_options([]) ->
	ok;
do_check_options([Opt={content_handlers, Handlers}|Opts]) ->
	case gun_content_handler:check_option(Handlers) of
		ok -> do_check_options(Opts);
		error -> {error, {options, {http, Opt}}}
	end;
do_check_options([{keepalive, infinity}|Opts]) ->
	do_check_options(Opts);
do_check_options([{keepalive, K}|Opts]) when is_integer(K), K > 0 ->
	do_check_options(Opts);
do_check_options([{transform_header_name, F}|Opts]) when is_function(F) ->
	do_check_options(Opts);
do_check_options([{version, V}|Opts]) when V =:= 'HTTP/1.1'; V =:= 'HTTP/1.0' ->
	do_check_options(Opts);
do_check_options([Opt|_]) ->
	{error, {options, {http, Opt}}}.

name() -> http.

init(Owner, Socket, Transport, Opts) ->
	Version = maps:get(version, Opts, 'HTTP/1.1'),
	Handlers = maps:get(content_handlers, Opts, [gun_data_h]),
	TransformHeaderName = maps:get(transform_header_name, Opts, fun (N) -> N end),
	#http_state{owner=Owner, socket=Socket, transport=Transport, version=Version,
		content_handlers=Handlers, transform_header_name=TransformHeaderName}.

%% Stop looping when we got no more data.
handle(<<>>, State) ->
	{state, State};
%% Close when server responds and we don't have any open streams.
handle(_, #http_state{streams=[]}) ->
	close;
%% Wait for the full response headers before trying to parse them.
handle(Data, State=#http_state{in=head, buffer=Buffer}) ->
	Data2 = << Buffer/binary, Data/binary >>,
	case binary:match(Data2, <<"\r\n\r\n">>) of
		nomatch -> {state, State#http_state{buffer=Data2}};
		{_, _} -> handle_head(Data2, State#http_state{buffer= <<>>})
	end;
%% Everything sent to the socket until it closes is part of the response body.
handle(Data, State=#http_state{in=body_close}) ->
	{state, send_data_if_alive(Data, State, nofin)};
%% Chunked transfer-encoding may contain both data and trailers.
handle(Data, State=#http_state{in=body_chunked, in_state=InState,
		buffer=Buffer, connection=Conn}) ->
	Buffer2 = << Buffer/binary, Data/binary >>,
	case cow_http_te:stream_chunked(Buffer2, InState) of
		more ->
			{state, State#http_state{buffer=Buffer2}};
		{more, Data2, InState2} ->
			{state, send_data_if_alive(Data2,
				State#http_state{buffer= <<>>, in_state=InState2},
				nofin)};
		{more, Data2, Length, InState2} when is_integer(Length) ->
			%% @todo See if we can recv faster than one message at a time.
			{state, send_data_if_alive(Data2,
				State#http_state{buffer= <<>>, in_state=InState2},
				nofin)};
		{more, Data2, Rest, InState2} ->
			%% @todo See if we can recv faster than one message at a time.
			{state, send_data_if_alive(Data2,
				State#http_state{buffer=Rest, in_state=InState2},
				nofin)};
		{done, HasTrailers, Rest} ->
			IsFin = case HasTrailers of
				trailers -> nofin;
				no_trailers -> fin
			end,
			%% I suppose it doesn't hurt to append an empty binary.
			State1 = send_data_if_alive(<<>>, State, IsFin),
			case {HasTrailers, Conn} of
				{trailers, _} ->
					handle(Rest, State1#http_state{buffer = <<>>, in=body_trailer});
				{no_trailers, keepalive} ->
					handle(Rest, end_stream(State1#http_state{buffer= <<>>}));
				{no_trailers, close} ->
					close
			end;
		{done, Data2, HasTrailers, Rest} ->
			IsFin = case HasTrailers of
				trailers -> nofin;
				no_trailers -> fin
			end,
			State1 = send_data_if_alive(Data2, State, IsFin),
			case {HasTrailers, Conn} of
				{trailers, _} ->
					handle(Rest, State1#http_state{buffer = <<>>, in=body_trailer});
				{no_trailers, keepalive} ->
					handle(Rest, end_stream(State1#http_state{buffer= <<>>}));
				{no_trailers, close} ->
					close
			end
	end;
handle(Data, State=#http_state{in=body_trailer, buffer=Buffer, connection=Conn,
		streams=[#stream{ref=StreamRef, reply_to=ReplyTo}|_]}) ->
	Data2 = << Buffer/binary, Data/binary >>,
	case binary:match(Data2, <<"\r\n\r\n">>) of
		nomatch -> {state, State#http_state{buffer=Data2}};
		{_, _} ->
			{Trailers, Rest} = cow_http:parse_headers(Data2),
			%% @todo We probably want to pass this to gun_content_handler?
			ReplyTo ! {gun_trailers, self(), stream_ref(StreamRef), Trailers},
			case Conn of
				keepalive ->
					handle(Rest, end_stream(State#http_state{buffer= <<>>}));
				close ->
					close
			end
	end;
%% We know the length of the rest of the body.
handle(Data, State=#http_state{in={body, Length}, connection=Conn}) ->
	DataSize = byte_size(Data),
	if
		%% More data coming.
		DataSize < Length ->
			{state, send_data_if_alive(Data,
				State#http_state{in={body, Length - DataSize}},
				nofin)};
		%% Stream finished, no rest.
		DataSize =:= Length ->
			State1 = send_data_if_alive(Data, State, fin),
			case Conn of
				keepalive -> {state, end_stream(State1)};
				close -> close
			end;
		%% Stream finished, rest.
		true ->
			<< Body:Length/binary, Rest/bits >> = Data,
			State1 = send_data_if_alive(Body, State, fin),
			case Conn of
				keepalive -> handle(Rest, end_stream(State1));
				close -> close
			end
	end.

handle_head(Data, State=#http_state{socket=Socket, version=ClientVersion,
		content_handlers=Handlers0, connection=Conn,
		streams=[Stream=#stream{ref=StreamRef, reply_to=ReplyTo,
			method=Method, is_alive=IsAlive}|Tail]}) ->
	{Version, Status, _, Rest} = cow_http:parse_status_line(Data),
	{Headers, Rest2} = cow_http:parse_headers(Rest),
	case {Status, StreamRef} of
		{101, {websocket, RealStreamRef, WsKey, WsExtensions, WsOpts}} ->
			ws_handshake(Rest2, State, RealStreamRef, Headers, WsKey, WsExtensions, WsOpts);
		{_, {connect, RealStreamRef, Destination}} when Status >= 200, Status < 300 ->
			case IsAlive of
				false ->
					ok;
				true ->
					ReplyTo ! {gun_response, self(), RealStreamRef,
						fin, Status, Headers},
					ok
			end,
			%% We expect there to be no additional data after the CONNECT response.
			<<>> = Rest2,
			State2 = end_stream(State#http_state{streams=[Stream|Tail]}),
			NewHost = maps:get(host, Destination),
			NewPort = maps:get(port, Destination),
			case Destination of
				#{transport := tls} ->
					TLSOpts = maps:get(tls_opts, Destination, []),
					TLSTimeout = maps:get(tls_handshake_timeout, Destination, infinity),
					case gun_tls:connect(Socket, TLSOpts, TLSTimeout) of
						{ok, TLSSocket} ->
							case ssl:negotiated_protocol(TLSSocket) of
								{ok, <<"h2">>} ->
									[{origin, <<"https">>, NewHost, NewPort, connect},
										{switch_transport, gun_tls, TLSSocket},
										{switch_protocol, gun_http2, State2}];
								_ ->
									[{state, State2#http_state{socket=TLSSocket, transport=gun_tls}},
										{origin, <<"https">>, NewHost, NewPort, connect},
										{switch_transport, gun_tls, TLSSocket}]
							end;
						Error ->
							Error
					end;
				_ ->
					case maps:get(protocols, Destination, [http]) of
						[http] ->
							[{state, State2},
								{origin, <<"http">>, NewHost, NewPort, connect}];
						[http2] ->
							[{origin, <<"http">>, NewHost, NewPort, connect},
								{switch_protocol, gun_http2, State2}]
					end
			end;
		{_, _} when Status >= 100, Status =< 199 ->
			ReplyTo ! {gun_inform, self(), stream_ref(StreamRef), Status, Headers},
			handle(Rest2, State);
		_ ->
			In = response_io_from_headers(Method, Version, Status, Headers),
			IsFin = case In of head -> fin; _ -> nofin end,
			Handlers = case IsAlive of
				false ->
					undefined;
				true ->
					ReplyTo ! {gun_response, self(), stream_ref(StreamRef),
						IsFin, Status, Headers},
					case IsFin of
						fin -> undefined;
						nofin ->
							gun_content_handler:init(ReplyTo, stream_ref(StreamRef),
								Status, Headers, Handlers0)
					end
			end,
			Conn2 = if
				Conn =:= close -> close;
				Version =:= 'HTTP/1.0' -> close;
				ClientVersion =:= 'HTTP/1.0' -> close;
				true -> conn_from_headers(Version, Headers)
			end,
			%% We always reset in_state even if not chunked.
			if
				IsFin =:= fin, Conn2 =:= close ->
					close;
				IsFin =:= fin ->
					handle(Rest2, end_stream(State#http_state{in=In,
						in_state={0, 0}, connection=Conn2,
						streams=[Stream#stream{handler_state=Handlers}|Tail]}));
				true ->
					handle(Rest2, State#http_state{in=In,
						in_state={0, 0}, connection=Conn2,
						streams=[Stream#stream{handler_state=Handlers}|Tail]})
			end
	end.

stream_ref({connect, StreamRef, _}) -> StreamRef;
stream_ref({websocket, StreamRef, _, _, _}) -> StreamRef;
stream_ref(StreamRef) -> StreamRef.

send_data_if_alive(<<>>, State, nofin) ->
	State;
%% @todo What if we receive data when the HEAD method was used?
send_data_if_alive(Data, State=#http_state{streams=[Stream=#stream{
		is_alive=true, handler_state=Handlers0}|Tail]}, IsFin) ->
	Handlers = gun_content_handler:handle(IsFin, Data, Handlers0),
	State#http_state{streams=[Stream#stream{handler_state=Handlers}|Tail]};
send_data_if_alive(_, State, _) ->
	State.

%% @todo Use Reason.
close(_, State=#http_state{in=body_close, streams=[_|Tail]}) ->
	_ = send_data_if_alive(<<>>, State, fin),
	close_streams(Tail);
close(_, #http_state{streams=Streams}) ->
	close_streams(Streams).

close_streams([]) ->
	ok;
close_streams([#stream{is_alive=false}|Tail]) ->
	close_streams(Tail);
close_streams([#stream{ref=StreamRef, reply_to=ReplyTo}|Tail]) ->
	ReplyTo ! {gun_error, self(), StreamRef, {closed,
		"The connection was lost."}},
	close_streams(Tail).

%% We don't send a keep-alive when a CONNECT request was initiated.
keepalive(State=#http_state{streams=[#stream{ref={connect, _, _}}]}) ->
	State;
%% We can only keep-alive by sending an empty line in-between streams.
keepalive(State=#http_state{socket=Socket, transport=Transport, out=head}) ->
	Transport:send(Socket, <<"\r\n">>),
	State;
keepalive(State) ->
	State.

request(State=#http_state{socket=Socket, transport=Transport, version=Version,
		out=head}, StreamRef, ReplyTo, Method, Host, Port, Path, Headers) ->
	Host2 = case Host of
		{local, _SocketPath} -> <<>>;
		Tuple when is_tuple(Tuple) -> inet:ntoa(Tuple);
		_ -> Host
	end,
	Headers2 = lists:keydelete(<<"transfer-encoding">>, 1, Headers),
	Headers3 = case lists:keymember(<<"host">>, 1, Headers) of
		false -> [{<<"host">>, [Host2, $:, integer_to_binary(Port)]}|Headers2];
		true -> Headers2
	end,
	%% We use Headers2 because this is the smallest list.
	Conn = conn_from_headers(Version, Headers2),
	Out = request_io_from_headers(Headers2),
	Headers4 = case Out of
		body_chunked when Version =:= 'HTTP/1.0' -> Headers3;
		body_chunked -> [{<<"transfer-encoding">>, <<"chunked">>}|Headers3];
		_ -> Headers3
	end,
	Headers5 = transform_header_names(State, Headers4),
	Transport:send(Socket, cow_http:request(Method, Path, Version, Headers5)),
	new_stream(State#http_state{connection=Conn, out=Out}, StreamRef, ReplyTo, Method).

request(State=#http_state{socket=Socket, transport=Transport, version=Version,
		out=head}, StreamRef, ReplyTo, Method, Host, Port, Path, Headers, Body) ->
	Host2 = case Host of
		{local, _SocketPath} -> <<>>;
		Tuple when is_tuple(Tuple) -> inet:ntoa(Tuple);
		_ -> Host
	end,
	Headers2 = lists:keydelete(<<"content-length">>, 1,
		lists:keydelete(<<"transfer-encoding">>, 1, Headers)),
	Headers3 = case lists:keymember(<<"host">>, 1, Headers) of
		false -> [{<<"host">>, [Host2, $:, integer_to_binary(Port)]}|Headers2];
		true -> Headers2
	end,
	Headers4 = transform_header_names(State, Headers3),
	%% We use Headers2 because this is the smallest list.
	Conn = conn_from_headers(Version, Headers2),
	Transport:send(Socket, [
		cow_http:request(Method, Path, Version, [
			{<<"content-length">>, integer_to_binary(iolist_size(Body))}
		|Headers4]),
		Body]),
	new_stream(State#http_state{connection=Conn}, StreamRef, ReplyTo, Method).

transform_header_names(#http_state{transform_header_name = Fun}, Headers) ->
	lists:keymap(Fun, 1, Headers).

%% We are expecting a new stream.
data(State=#http_state{out=head}, StreamRef, ReplyTo, _, _) ->
	error_stream_closed(State, StreamRef, ReplyTo);
%% There are no active streams.
data(State=#http_state{streams=[]}, StreamRef, ReplyTo, _, _) ->
	error_stream_not_found(State, StreamRef, ReplyTo);
%% We can only send data on the last created stream.
data(State=#http_state{socket=Socket, transport=Transport, version=Version,
		out=Out, streams=Streams}, StreamRef, ReplyTo, IsFin, Data) ->
	case lists:last(Streams) of
		#stream{ref=StreamRef, is_alive=true} ->
			DataLength = iolist_size(Data),
			case Out of
				body_chunked when Version =:= 'HTTP/1.1', IsFin =:= fin ->
					case Data of
						<<>> ->
							Transport:send(Socket, cow_http_te:last_chunk());
						_ ->
							Transport:send(Socket, [
								cow_http_te:chunk(Data),
								cow_http_te:last_chunk()
							])
					end,
					State#http_state{out=head};
				body_chunked when Version =:= 'HTTP/1.1' ->
					Transport:send(Socket, cow_http_te:chunk(Data)),
					State;
				{body, Length} when DataLength =< Length ->
					Transport:send(Socket, Data),
					Length2 = Length - DataLength,
					if
						Length2 =:= 0, IsFin =:= fin ->
							State#http_state{out=head};
						Length2 > 0, IsFin =:= nofin ->
							State#http_state{out={body, Length2}}
					end;
				body_chunked -> %% HTTP/1.0
					Transport:send(Socket, Data),
					State
			end;
		_ ->
			error_stream_not_found(State, StreamRef, ReplyTo)
	end.

connect(State=#http_state{streams=Streams}, StreamRef, ReplyTo, _, _) when Streams =/= [] ->
	ReplyTo ! {gun_error, self(), StreamRef, {badstate,
		"CONNECT can only be used with HTTP/1.1 when no other streams are active."}},
	State;
connect(State=#http_state{socket=Socket, transport=Transport, version=Version},
		StreamRef, ReplyTo, Destination=#{host := Host0}, Headers0) ->
	Host = case Host0 of
		Tuple when is_tuple(Tuple) -> inet:ntoa(Tuple);
		_ -> Host0
	end,
	Port = maps:get(port, Destination, 1080),
	Authority = [Host, $:, integer_to_binary(Port)],
	Headers1 = lists:keydelete(<<"content-length">>, 1,
		lists:keydelete(<<"transfer-encoding">>, 1, Headers0)),
	Headers2 = case lists:keymember(<<"host">>, 1, Headers1) of
		false -> [{<<"host">>, Authority}|Headers1];
		true -> Headers1
	end,
	HasProxyAuthorization = lists:keymember(<<"proxy-authorization">>, 1, Headers2),
	Headers3 = case {HasProxyAuthorization, Destination} of
		{false, #{username := UserID, password := Password}} ->
			[{<<"proxy-authorization">>, [
					<<"Basic ">>,
					base64:encode(iolist_to_binary([UserID, $:, Password]))]}
				|Headers2];
		_ ->
			Headers2
	end,
	Headers = transform_header_names(State, Headers3),
	Transport:send(Socket, [
		cow_http:request(<<"CONNECT">>, Authority, Version, Headers)
	]),
	new_stream(State, {connect, StreamRef, Destination}, ReplyTo, <<"CONNECT">>).

%% We can't cancel anything, we can just stop forwarding messages to the owner.
cancel(State, StreamRef, ReplyTo) ->
	case is_stream(State, StreamRef) of
		true ->
			cancel_stream(State, StreamRef);
		false ->
			error_stream_not_found(State, StreamRef, ReplyTo)
	end.

%% HTTP does not provide any way to figure out what streams are unprocessed.
down(#http_state{streams=Streams}) ->
	KilledStreams = [case Ref of
		{connect, Ref2, _} -> Ref2;
		{websocket, Ref2, _, _, _} -> Ref2;
		_ -> Ref
	end || #stream{ref=Ref} <- Streams],
	{KilledStreams, []}.

error_stream_closed(State, StreamRef, ReplyTo) ->
	ReplyTo ! {gun_error, self(), StreamRef, {badstate,
		"The stream has already been closed."}},
	State.

error_stream_not_found(State, StreamRef, ReplyTo) ->
	ReplyTo ! {gun_error, self(), StreamRef, {badstate,
		"The stream cannot be found."}},
	State.

%% Headers information retrieval.

conn_from_headers(Version, Headers) ->
	case lists:keyfind(<<"connection">>, 1, Headers) of
		false when Version =:= 'HTTP/1.0' ->
			close;
		false ->
			keepalive;
		{_, ConnHd} ->
			ConnList = cow_http_hd:parse_connection(ConnHd),
			case lists:member(<<"keep-alive">>, ConnList) of
				true -> keepalive;
				false -> close
			end
	end.

request_io_from_headers(Headers) ->
	case lists:keyfind(<<"content-length">>, 1, Headers) of
		{_, <<"0">>} ->
			head;
		{_, Length} ->
			{body, cow_http_hd:parse_content_length(Length)};
		_ ->
			case lists:keymember(<<"content-type">>, 1, Headers) of
				true -> body_chunked;
				false -> head
			end
	end.

response_io_from_headers(<<"HEAD">>, _, _, _) ->
	head;
response_io_from_headers(_, _, Status, _) when (Status =:= 204) or (Status =:= 304) ->
	head;
response_io_from_headers(_, Version, _Status, Headers) ->
	case lists:keyfind(<<"content-length">>, 1, Headers) of
		{_, <<"0">>} ->
			head;
		{_, Length} ->
			{body, cow_http_hd:parse_content_length(Length)};
		_ when Version =:= 'HTTP/1.0' ->
			body_close;
		_ ->
			case lists:keyfind(<<"transfer-encoding">>, 1, Headers) of
				false ->
					body_close;
				{_, TE} ->
					case cow_http_hd:parse_transfer_encoding(TE) of
						[<<"chunked">>] -> body_chunked;
						[<<"identity">>] -> body_close
					end
			end
	end.

%% Streams.

new_stream(State=#http_state{streams=Streams}, StreamRef, ReplyTo, Method) ->
	State#http_state{streams=Streams
		++ [#stream{ref=StreamRef, reply_to=ReplyTo,
			method=iolist_to_binary(Method), is_alive=true}]}.

is_stream(#http_state{streams=Streams}, StreamRef) ->
	lists:keymember(StreamRef, #stream.ref, Streams).

cancel_stream(State=#http_state{streams=Streams}, StreamRef) ->
	Streams2 = [case Ref of
		StreamRef ->
			Tuple#stream{is_alive=false};
		_ ->
			Tuple
	end || Tuple = #stream{ref=Ref} <- Streams],
	State#http_state{streams=Streams2}.

end_stream(State=#http_state{streams=[_|Tail]}) ->
	State#http_state{in=head, streams=Tail}.

%% Websocket upgrade.

%% Ensure version is 1.1.
ws_upgrade(#http_state{version='HTTP/1.0'}, _, _, _, _, _, _) ->
	error; %% @todo
ws_upgrade(State=#http_state{socket=Socket, transport=Transport, owner=Owner, out=head},
		StreamRef, Host, Port, Path, Headers0, WsOpts) ->
	{Headers1, GunExtensions} = case maps:get(compress, WsOpts, false) of
		true -> {[{<<"sec-websocket-extensions">>,
				<<"permessage-deflate; client_max_window_bits; server_max_window_bits=15">>}
			|Headers0],
			[<<"permessage-deflate">>]};
		false -> {Headers0, []}
	end,
	Headers2 = case maps:get(protocols, WsOpts, []) of
		[] -> Headers1;
		ProtoOpt ->
			<< _, _, Proto/bits >> = iolist_to_binary([[<<", ">>, P] || {P, _} <- ProtoOpt]),
			[{<<"sec-websocket-protocol">>, Proto}|Headers1]
	end,
	Key = cow_ws:key(),
	Headers3 = [
		{<<"connection">>, <<"upgrade">>},
		{<<"upgrade">>, <<"websocket">>},
		{<<"sec-websocket-version">>, <<"13">>},
		{<<"sec-websocket-key">>, Key}
		|Headers2
	],
	IsSecure = Transport =:= gun_tls,
	Headers = case lists:keymember(<<"host">>, 1, Headers0) of
		true -> Headers3;
		false when Port =:= 80, not IsSecure -> [{<<"host">>, Host}|Headers3];
		false when Port =:= 443, IsSecure -> [{<<"host">>, Host}|Headers3];
		false -> [{<<"host">>, [Host, $:, integer_to_binary(Port)]}|Headers3]
	end,
	Transport:send(Socket, cow_http:request(<<"GET">>, Path, 'HTTP/1.1', Headers)),
	new_stream(State#http_state{connection=keepalive, out=head},
		{websocket, StreamRef, Key, GunExtensions, WsOpts}, Owner, <<"GET">>).

ws_handshake(Buffer, State, StreamRef, Headers, Key, GunExtensions, Opts) ->
	%% @todo check upgrade, connection
	case lists:keyfind(<<"sec-websocket-accept">>, 1, Headers) of
		false ->
			close;
		{_, Accept} ->
			case cow_ws:encode_key(Key) of
				Accept ->
					ws_handshake_extensions(Buffer, State, StreamRef,
						Headers, GunExtensions, Opts);
				_ ->
					close
			end
	end.

ws_handshake_extensions(Buffer, State, StreamRef, Headers, GunExtensions, Opts) ->
	case lists:keyfind(<<"sec-websocket-extensions">>, 1, Headers) of
		false ->
			ws_handshake_protocols(Buffer, State, StreamRef, Headers, #{}, Opts);
		{_, ExtHd} ->
			case ws_validate_extensions(cow_http_hd:parse_sec_websocket_extensions(ExtHd), GunExtensions, #{}, Opts) of
				close ->
					close;
				Extensions ->
					ws_handshake_protocols(Buffer, State, StreamRef, Headers, Extensions, Opts)
			end
	end.

ws_validate_extensions([], _, Acc, _) ->
	Acc;
ws_validate_extensions([{Name = <<"permessage-deflate">>, Params}|Tail], GunExts, Acc, Opts) ->
	case lists:member(Name, GunExts) of
		true ->
			case cow_ws:validate_permessage_deflate(Params, Acc, Opts) of
				{ok, Acc2} -> ws_validate_extensions(Tail, GunExts, Acc2, Opts);
				error -> close
			end;
		%% Fail the connection if extension was not requested.
		false ->
			close
	end;
%% Fail the connection on unknown extension.
ws_validate_extensions(_, _, _, _) ->
	close.

%% @todo Validate protocols.
ws_handshake_protocols(Buffer, State, StreamRef, Headers, Extensions, Opts) ->
	case lists:keyfind(<<"sec-websocket-protocol">>, 1, Headers) of
		false ->
			ws_handshake_end(Buffer, State, StreamRef, Headers, Extensions,
				maps:get(default_protocol, Opts, gun_ws_h), Opts);
		{_, Proto} ->
			ProtoOpt = maps:get(protocols, Opts, []),
			case lists:keyfind(Proto, 1, ProtoOpt) of
				{_, Handler} ->
					ws_handshake_end(Buffer, State, StreamRef,
						Headers, Extensions, Handler, Opts);
				false ->
					close
			end
	end.

ws_handshake_end(Buffer, #http_state{owner=Owner, socket=Socket, transport=Transport},
		StreamRef, Headers, Extensions, Handler, Opts) ->
	%% Send ourselves the remaining buffer, if any.
	_ = case Buffer of
		<<>> ->
			ok;
		_ ->
			{OK, _, _} = Transport:messages(),
			self() ! {OK, Socket, Buffer}
	end,
	gun_ws:init(Owner, Socket, Transport, StreamRef, Headers, Extensions, Handler, Opts).