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
|
%% Copyright (c) 2015-2017, 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_stream).
-type state() :: any().
-type human_reason() :: atom().
-type streamid() :: any().
-export_type([streamid/0]).
-type fin() :: fin | nofin.
-export_type([fin/0]).
%% @todo Perhaps it makes more sense to have resp_body in this module?
-type resp_command()
:: {response, cowboy:http_status(), cowboy:http_headers(), cowboy_req:resp_body()}.
-export_type([resp_command/0]).
-type commands() :: [resp_command()
| {headers, cowboy:http_status(), cowboy:http_headers()}
| {data, fin(), iodata()}
| {push, binary(), binary(), binary(), inet:port_number(),
binary(), binary(), cowboy:http_headers()}
| {flow, auto | integer()}
| {spawn, pid(), timeout()}
| {error_response, cowboy:http_status(), cowboy:http_headers(), iodata()}
| {switch_protocol, cowboy:http_headers(), module(), state()}
| {internal_error, any(), human_reason()}
| stop].
-export_type([commands/0]).
-type reason() :: normal
| {internal_error, timeout | {error | exit | throw, any()}, human_reason()}
| {socket_error, closed | atom(), human_reason()}
| {stream_error, cow_http2:error(), human_reason()}
| {connection_error, cow_http2:error(), human_reason()}
| {stop, cow_http2:frame(), human_reason()}.
-export_type([reason/0]).
-type partial_req() :: map(). %% @todo Take what's in cowboy_req with everything? optional.
-export_type([partial_req/0]).
-callback init(streamid(), cowboy_req:req(), cowboy:opts()) -> {commands(), state()}.
-callback data(streamid(), fin(), binary(), State) -> {commands(), State} when State::state().
-callback info(streamid(), any(), State) -> {commands(), State} when State::state().
-callback terminate(streamid(), reason(), state()) -> any().
-callback early_error(streamid(), reason(), partial_req(), Resp, cowboy:opts())
-> Resp when Resp::resp_command().
%% @todo To optimize the number of active timers we could have a command
%% that enables a timeout that is called in the absence of any other call,
%% similar to what gen_server does. However the nice thing about this is
%% that the connection process can keep a single timer around (the same
%% one that would be used to detect half-closed sockets) and use this
%% timer and other events to trigger the timeout in streams at their
%% intended time.
%%
%% This same timer can be used to try and send PING frames to help detect
%% that the connection is indeed unresponsive.
-export([init/3]).
-export([data/4]).
-export([info/3]).
-export([terminate/3]).
-export([early_error/5]).
-export([report_error/5]).
%% Note that this and other functions in this module do NOT catch
%% exceptions. We want the exception to go all the way down to the
%% protocol code.
%%
%% OK the failure scenario is not so clear. The problem is
%% that the failure at any point in init/3 will result in the
%% corresponding state being lost. I am unfortunately not
%% confident we can do anything about this. If the crashing
%% handler just created a process, we'll never know about it.
%% Therefore at this time I choose to leave all failure handling
%% to the protocol process.
%%
%% Note that a failure in init/3 will result in terminate/3
%% NOT being called. This is because the state is not available.
-spec init(streamid(), cowboy_req:req(), cowboy:opts())
-> {commands(), {module(), state()} | undefined}.
init(StreamID, Req, Opts) ->
case maps:get(stream_handlers, Opts, [cowboy_stream_h]) of
[] ->
{[], undefined};
[Handler|Tail] ->
%% We call the next handler and remove it from the list of
%% stream handlers. This means that handlers that run after
%% it have no knowledge it exists. Should user require this
%% knowledge they can just define a separate option that will
%% be left untouched.
{Commands, State} = Handler:init(StreamID, Req, Opts#{stream_handlers => Tail}),
{Commands, {Handler, State}}
end.
-spec data(streamid(), fin(), binary(), {Handler, State} | undefined)
-> {commands(), {Handler, State} | undefined}
when Handler::module(), State::state().
data(_, _, _, undefined) ->
{[], undefined};
data(StreamID, IsFin, Data, {Handler, State0}) ->
{Commands, State} = Handler:data(StreamID, IsFin, Data, State0),
{Commands, {Handler, State}}.
-spec info(streamid(), any(), {Handler, State} | undefined)
-> {commands(), {Handler, State} | undefined}
when Handler::module(), State::state().
info(_, _, undefined) ->
{[], undefined};
info(StreamID, Info, {Handler, State0}) ->
{Commands, State} = Handler:info(StreamID, Info, State0),
{Commands, {Handler, State}}.
-spec terminate(streamid(), reason(), {module(), state()} | undefined) -> ok.
terminate(_, _, undefined) ->
ok;
terminate(StreamID, Reason, {Handler, State}) ->
_ = Handler:terminate(StreamID, Reason, State),
ok.
-spec early_error(streamid(), reason(), partial_req(), Resp, cowboy:opts())
-> Resp when Resp::resp_command().
early_error(StreamID, Reason, PartialReq, Resp, Opts) ->
case maps:get(stream_handlers, Opts, [cowboy_stream_h]) of
[] ->
Resp;
[Handler|Tail] ->
%% This is the same behavior as in init/3.
Handler:early_error(StreamID, Reason,
PartialReq, Resp, Opts#{stream_handlers => Tail})
end.
-spec report_error(atom(), list(), error | exit | throw, any(), list()) -> ok.
report_error(init, [StreamID, Req, Opts], Class, Exception, Stacktrace) ->
error_logger:error_msg(
"Unhandled exception ~p:~p in cowboy_stream:init(~p, Req, Opts)~n"
"Stacktrace: ~p~n"
"Req: ~p~n"
"Opts: ~p~n",
[Class, Exception, StreamID, Stacktrace, Req, Opts]);
report_error(data, [StreamID, IsFin, Data, State], Class, Exception, Stacktrace) ->
error_logger:error_msg(
"Unhandled exception ~p:~p in cowboy_stream:data(~p, ~p, Data, State)~n"
"Stacktrace: ~p~n"
"Data: ~p~n"
"State: ~p~n",
[Class, Exception, StreamID, IsFin, Stacktrace, Data, State]);
report_error(info, [StreamID, Msg, State], Class, Exception, Stacktrace) ->
error_logger:error_msg(
"Unhandled exception ~p:~p in cowboy_stream:info(~p, Msg, State)~n"
"Stacktrace: ~p~n"
"Msg: ~p~n"
"State: ~p~n",
[Class, Exception, StreamID, Stacktrace, Msg, State]);
report_error(terminate, [StreamID, Reason, State], Class, Exception, Stacktrace) ->
error_logger:error_msg(
"Unhandled exception ~p:~p in cowboy_stream:terminate(~p, Reason, State)~n"
"Stacktrace: ~p~n"
"Reason: ~p~n"
"State: ~p~n",
[Class, Exception, StreamID, Stacktrace, Reason, State]);
report_error(early_error, [StreamID, Reason, PartialReq, Resp, Opts], Class, Exception, Stacktrace) ->
error_logger:error_msg(
"Unhandled exception ~p:~p in cowboy_stream:early_error(~p, Reason, PartialReq, Resp, Opts)~n"
"Stacktrace: ~p~n"
"Reason: ~p~n"
"PartialReq: ~p~n"
"Resp: ~p~n"
"Opts: ~p~n",
[Class, Exception, StreamID, Stacktrace, Reason, PartialReq, Resp, Opts]);
report_error(Callback, _, Class, Reason, Stacktrace) ->
error_logger:error_msg(
"Exception occurred in unknown callback ~p~n"
"Reason: ~p:~p~n"
"Stacktrace: ~p~n",
[Callback, Class, Reason, Stacktrace]).
|
