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
|
%% Copyright (c) 2017, 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(cowboy_compress_h).
-behavior(cowboy_stream).
-export([init/3]).
-export([data/4]).
-export([info/3]).
-export([terminate/3]).
-export([early_error/5]).
-record(state, {
next :: any(),
threshold :: non_neg_integer() | undefined,
compress = undefined :: undefined | gzip,
deflate = undefined :: undefined | zlib:zstream()
}).
-spec init(cowboy_stream:streamid(), cowboy_req:req(), cowboy:opts())
-> {cowboy_stream:commands(), #state{}}.
init(StreamID, Req, Opts) ->
State0 = check_req(Req),
CompressThreshold = maps:get(compress_threshold, Opts, 300),
{Commands0, Next} = cowboy_stream:init(StreamID, Req, Opts),
fold(Commands0, State0#state{next=Next, threshold=CompressThreshold}).
-spec data(cowboy_stream:streamid(), cowboy_stream:fin(), cowboy_req:resp_body(), State)
-> {cowboy_stream:commands(), State} when State::#state{}.
data(StreamID, IsFin, Data, State0=#state{next=Next0}) ->
{Commands0, Next} = cowboy_stream:data(StreamID, IsFin, Data, Next0),
fold(Commands0, State0#state{next=Next}).
-spec info(cowboy_stream:streamid(), any(), State)
-> {cowboy_stream:commands(), State} when State::#state{}.
info(StreamID, Info, State0=#state{next=Next0}) ->
{Commands0, Next} = cowboy_stream:info(StreamID, Info, Next0),
fold(Commands0, State0#state{next=Next}).
-spec terminate(cowboy_stream:streamid(), cowboy_stream:reason(), #state{}) -> any().
terminate(StreamID, Reason, #state{next=Next, deflate=Z}) ->
%% Clean the zlib:stream() in case something went wrong.
%% In the normal scenario the stream is already closed.
case Z of
undefined -> ok;
_ -> zlib:close(Z)
end,
cowboy_stream:terminate(StreamID, Reason, Next).
-spec early_error(cowboy_stream:streamid(), cowboy_stream:reason(),
cowboy_stream:partial_req(), Resp, cowboy:opts()) -> Resp
when Resp::cowboy_stream:resp_command().
early_error(StreamID, Reason, PartialReq, Resp, Opts) ->
cowboy_stream:early_error(StreamID, Reason, PartialReq, Resp, Opts).
%% Internal.
%% Check if the client supports decoding of gzip responses.
check_req(Req) ->
%% @todo Probably shouldn't unconditionally crash on failure.
case cowboy_req:parse_header(<<"accept-encoding">>, Req) of
%% Client doesn't support any compression algorithm.
undefined ->
#state{compress=undefined};
Encodings ->
%% We only support gzip so look for it specifically.
%% @todo A recipient SHOULD consider "x-gzip" to be
%% equivalent to "gzip". (RFC7230 4.2.3)
case [E || E={<<"gzip">>, Q} <- Encodings, Q =/= 0] of
[] ->
#state{compress=undefined};
_ ->
#state{compress=gzip}
end
end.
%% Do not compress responses that contain the content-encoding header.
check_resp_headers(#{<<"content-encoding">> := _}, State) ->
State#state{compress=undefined};
check_resp_headers(_, State) ->
State.
fold(Commands, State=#state{compress=undefined}) ->
{Commands, State};
fold(Commands, State) ->
fold(Commands, State, []).
fold([], State, Acc) ->
{lists:reverse(Acc), State};
%% We do not compress full sendfile bodies.
fold([Response={response, _, _, {sendfile, _, _, _}}|Tail], State, Acc) ->
fold(Tail, State, [Response|Acc]);
%% We compress full responses directly, unless they are lower than
%% the configured threshold or we find we are not able to by looking at the headers.
fold([Response0={response, _, Headers, Body}|Tail],
State0=#state{threshold=CompressThreshold}, Acc) ->
case check_resp_headers(Headers, State0) of
State=#state{compress=undefined} ->
fold(Tail, State, [Response0|Acc]);
State1 ->
BodyLength = iolist_size(Body),
if
BodyLength =< CompressThreshold ->
fold(Tail, State1, [Response0|Acc]);
true ->
{Response, State} = gzip_response(Response0, State1),
fold(Tail, State, [Response|Acc])
end
end;
%% Check headers and initiate compression...
fold([Response0={headers, _, Headers}|Tail], State0, Acc) ->
case check_resp_headers(Headers, State0) of
State=#state{compress=undefined} ->
fold(Tail, State, [Response0|Acc]);
State1 ->
{Response, State} = gzip_headers(Response0, State1),
fold(Tail, State, [Response|Acc])
end;
%% then compress each data commands individually.
fold([Data0={data, _, _}|Tail], State0=#state{compress=gzip}, Acc) ->
{Data, State} = gzip_data(Data0, State0),
fold(Tail, State, [Data|Acc]);
%% When trailers are sent we need to end the compression.
%% This results in an extra data command being sent.
fold([Trailers={trailers, _}|Tail], State0=#state{compress=gzip}, Acc) ->
{{data, fin, Data}, State} = gzip_data({data, fin, <<>>}, State0),
fold(Tail, State, [Trailers, {data, nofin, Data}|Acc]);
%% Otherwise, we have an unrelated command or compression is disabled.
fold([Command|Tail], State, Acc) ->
fold(Tail, State, [Command|Acc]).
gzip_response({response, Status, Headers, Body}, State) ->
%% We can't call zlib:gzip/1 because it does an
%% iolist_to_binary(GzBody) at the end to return
%% a binary(). Therefore the code here is largely
%% a duplicate of the code of that function.
Z = zlib:open(),
GzBody = try
%% 31 = 16+?MAX_WBITS from zlib.erl
%% @todo It might be good to allow them to be configured?
zlib:deflateInit(Z, default, deflated, 31, 8, default),
Gz = zlib:deflate(Z, Body, finish),
zlib:deflateEnd(Z),
Gz
after
zlib:close(Z)
end,
{{response, Status, Headers#{
<<"content-length">> => integer_to_binary(iolist_size(GzBody)),
<<"content-encoding">> => <<"gzip">>
}, GzBody}, State}.
gzip_headers({headers, Status, Headers0}, State) ->
Z = zlib:open(),
%% We use the same arguments as when compressing the body fully.
%% @todo It might be good to allow them to be configured?
zlib:deflateInit(Z, default, deflated, 31, 8, default),
Headers = maps:remove(<<"content-length">>, Headers0),
{{headers, Status, Headers#{
<<"content-encoding">> => <<"gzip">>
}}, State#state{deflate=Z}}.
%% It is not possible to combine zlib and the sendfile
%% syscall as far as I can tell, because the zlib format
%% includes a checksum at the end of the stream. We have
%% to read the file in memory, making this not suitable for
%% large files.
gzip_data({data, nofin, Sendfile={sendfile, _, _, _}}, State=#state{deflate=Z}) ->
{ok, Data0} = read_file(Sendfile),
Data = zlib:deflate(Z, Data0),
{{data, nofin, Data}, State};
gzip_data({data, fin, Sendfile={sendfile, _, _, _}}, State=#state{deflate=Z}) ->
{ok, Data0} = read_file(Sendfile),
Data = zlib:deflate(Z, Data0, finish),
zlib:deflateEnd(Z),
zlib:close(Z),
{{data, fin, Data}, State#state{deflate=undefined}};
gzip_data({data, nofin, Data0}, State=#state{deflate=Z}) ->
Data = zlib:deflate(Z, Data0),
{{data, nofin, Data}, State};
gzip_data({data, fin, Data0}, State=#state{deflate=Z}) ->
Data = zlib:deflate(Z, Data0, finish),
zlib:deflateEnd(Z),
zlib:close(Z),
{{data, fin, Data}, State#state{deflate=undefined}}.
read_file({sendfile, Offset, Bytes, Path}) ->
{ok, IoDevice} = file:open(Path, [read, raw, binary]),
try
_ = case Offset of
0 -> ok;
_ -> file:position(IoDevice, {bof, Offset})
end,
file:read(IoDevice, Bytes)
after
file:close(IoDevice)
end.
|
