diff options
Diffstat (limited to 'server/_build/default/lib/cowboy/src/cowboy_rest.erl')
| -rw-r--r-- | server/_build/default/lib/cowboy/src/cowboy_rest.erl | 1637 |
1 files changed, 1637 insertions, 0 deletions
diff --git a/server/_build/default/lib/cowboy/src/cowboy_rest.erl b/server/_build/default/lib/cowboy/src/cowboy_rest.erl new file mode 100644 index 0000000..7d0fe80 --- /dev/null +++ b/server/_build/default/lib/cowboy/src/cowboy_rest.erl @@ -0,0 +1,1637 @@ +%% Copyright (c) 2011-2017, Loïc Hoguin <essen@ninenines.eu> +%% +%% 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. + +%% Originally based on the Webmachine Diagram from Alan Dean and +%% Justin Sheehy. +-module(cowboy_rest). +-behaviour(cowboy_sub_protocol). + +-export([upgrade/4]). +-export([upgrade/5]). + +-type switch_handler() :: {switch_handler, module()} + | {switch_handler, module(), any()}. + +%% Common handler callbacks. + +-callback init(Req, any()) + -> {ok | module(), Req, any()} + | {module(), Req, any(), any()} + when Req::cowboy_req:req(). + +-callback terminate(any(), cowboy_req:req(), any()) -> ok. +-optional_callbacks([terminate/3]). + +%% REST handler callbacks. + +-callback allowed_methods(Req, State) + -> {[binary()], Req, State} + | {stop, Req, State} + | {switch_handler(), Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([allowed_methods/2]). + +-callback allow_missing_post(Req, State) + -> {boolean(), Req, State} + | {stop, Req, State} + | {switch_handler(), Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([allow_missing_post/2]). + +-callback charsets_provided(Req, State) + -> {[binary()], Req, State} + | {stop, Req, State} + | {switch_handler(), Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([charsets_provided/2]). + +-callback content_types_accepted(Req, State) + -> {[{'*' | binary() | {binary(), binary(), '*' | [{binary(), binary()}]}, atom()}], Req, State} + | {stop, Req, State} + | {switch_handler(), Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([content_types_accepted/2]). + +-callback content_types_provided(Req, State) + -> {[{binary() | {binary(), binary(), '*' | [{binary(), binary()}]}, atom()}], Req, State} + | {stop, Req, State} + | {switch_handler(), Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([content_types_provided/2]). + +-callback delete_completed(Req, State) + -> {boolean(), Req, State} + | {stop, Req, State} + | {switch_handler(), Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([delete_completed/2]). + +-callback delete_resource(Req, State) + -> {boolean(), Req, State} + | {stop, Req, State} + | {switch_handler(), Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([delete_resource/2]). + +-callback expires(Req, State) + -> {calendar:datetime() | binary() | undefined, Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([expires/2]). + +-callback forbidden(Req, State) + -> {boolean(), Req, State} + | {stop, Req, State} + | {switch_handler(), Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([forbidden/2]). + +-callback generate_etag(Req, State) + -> {binary() | {weak | strong, binary()}, Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([generate_etag/2]). + +-callback is_authorized(Req, State) + -> {true | {false, iodata()}, Req, State} + | {stop, Req, State} + | {switch_handler(), Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([is_authorized/2]). + +-callback is_conflict(Req, State) + -> {boolean(), Req, State} + | {stop, Req, State} + | {switch_handler(), Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([is_conflict/2]). + +-callback known_methods(Req, State) + -> {[binary()], Req, State} + | {stop, Req, State} + | {switch_handler(), Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([known_methods/2]). + +-callback languages_provided(Req, State) + -> {[binary()], Req, State} + | {stop, Req, State} + | {switch_handler(), Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([languages_provided/2]). + +-callback last_modified(Req, State) + -> {calendar:datetime(), Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([last_modified/2]). + +-callback malformed_request(Req, State) + -> {boolean(), Req, State} + | {stop, Req, State} + | {switch_handler(), Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([malformed_request/2]). + +-callback moved_permanently(Req, State) + -> {{true, iodata()} | false, Req, State} + | {stop, Req, State} + | {switch_handler(), Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([moved_permanently/2]). + +-callback moved_temporarily(Req, State) + -> {{true, iodata()} | false, Req, State} + | {stop, Req, State} + | {switch_handler(), Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([moved_temporarily/2]). + +-callback multiple_choices(Req, State) + -> {boolean(), Req, State} + | {stop, Req, State} + | {switch_handler(), Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([multiple_choices/2]). + +-callback options(Req, State) + -> {ok, Req, State} + | {stop, Req, State} + | {switch_handler(), Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([options/2]). + +-callback previously_existed(Req, State) + -> {boolean(), Req, State} + | {stop, Req, State} + | {switch_handler(), Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([previously_existed/2]). + +-callback range_satisfiable(Req, State) + -> {boolean() | {false, non_neg_integer() | iodata()}, Req, State} + | {stop, Req, State} + | {switch_handler(), Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([range_satisfiable/2]). + +-callback ranges_provided(Req, State) + -> {[{binary(), atom()}], Req, State} + | {stop, Req, State} + | {switch_handler(), Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([ranges_provided/2]). + +-callback rate_limited(Req, State) + -> {{true, non_neg_integer() | calendar:datetime()} | false, Req, State} + | {stop, Req, State} + | {switch_handler(), Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([rate_limited/2]). + +-callback resource_exists(Req, State) + -> {boolean(), Req, State} + | {stop, Req, State} + | {switch_handler(), Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([resource_exists/2]). + +-callback service_available(Req, State) + -> {boolean(), Req, State} + | {stop, Req, State} + | {switch_handler(), Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([service_available/2]). + +-callback uri_too_long(Req, State) + -> {boolean(), Req, State} + | {stop, Req, State} + | {switch_handler(), Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([uri_too_long/2]). + +-callback valid_content_headers(Req, State) + -> {boolean(), Req, State} + | {stop, Req, State} + | {switch_handler(), Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([valid_content_headers/2]). + +-callback valid_entity_length(Req, State) + -> {boolean(), Req, State} + | {stop, Req, State} + | {switch_handler(), Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([valid_entity_length/2]). + +-callback variances(Req, State) + -> {[binary()], Req, State} + when Req::cowboy_req:req(), State::any(). +-optional_callbacks([variances/2]). + +%% End of REST callbacks. Whew! + +-record(state, { + method = undefined :: binary(), + + %% Handler. + handler :: atom(), + handler_state :: any(), + + %% Allowed methods. Only used for OPTIONS requests. + allowed_methods :: [binary()] | undefined, + + %% Media type. + content_types_p = [] :: + [{binary() | {binary(), binary(), [{binary(), binary()}] | '*'}, + atom()}], + content_type_a :: undefined + | {binary() | {binary(), binary(), [{binary(), binary()}] | '*'}, + atom()}, + + %% Language. + languages_p = [] :: [binary()], + language_a :: undefined | binary(), + + %% Charset. + charsets_p = undefined :: undefined | [binary()], + charset_a :: undefined | binary(), + + %% Range units. + ranges_a = [] :: [{binary(), atom()}], + + %% Whether the resource exists. + exists = false :: boolean(), + + %% Cached resource calls. + etag :: undefined | no_call | {strong | weak, binary()}, + last_modified :: undefined | no_call | calendar:datetime(), + expires :: undefined | no_call | calendar:datetime() | binary() +}). + +-spec upgrade(Req, Env, module(), any()) + -> {ok, Req, Env} when Req::cowboy_req:req(), Env::cowboy_middleware:env(). +upgrade(Req0, Env, Handler, HandlerState0) -> + Method = cowboy_req:method(Req0), + case service_available(Req0, #state{method=Method, + handler=Handler, handler_state=HandlerState0}) of + {ok, Req, Result} -> + {ok, Req, Env#{result => Result}}; + {Mod, Req, HandlerState} -> + Mod:upgrade(Req, Env, Handler, HandlerState); + {Mod, Req, HandlerState, Opts} -> + Mod:upgrade(Req, Env, Handler, HandlerState, Opts) + end. + +-spec upgrade(Req, Env, module(), any(), any()) + -> {ok, Req, Env} when Req::cowboy_req:req(), Env::cowboy_middleware:env(). +%% cowboy_rest takes no options. +upgrade(Req, Env, Handler, HandlerState, _Opts) -> + upgrade(Req, Env, Handler, HandlerState). + +service_available(Req, State) -> + expect(Req, State, service_available, true, fun known_methods/2, 503). + +%% known_methods/2 should return a list of binary methods. +known_methods(Req, State=#state{method=Method}) -> + case call(Req, State, known_methods) of + no_call when Method =:= <<"HEAD">>; Method =:= <<"GET">>; + Method =:= <<"POST">>; Method =:= <<"PUT">>; + Method =:= <<"PATCH">>; Method =:= <<"DELETE">>; + Method =:= <<"OPTIONS">> -> + next(Req, State, fun uri_too_long/2); + no_call -> + next(Req, State, 501); + {stop, Req2, State2} -> + terminate(Req2, State2); + {Switch, Req2, State2} when element(1, Switch) =:= switch_handler -> + switch_handler(Switch, Req2, State2); + {List, Req2, State2} -> + case lists:member(Method, List) of + true -> next(Req2, State2, fun uri_too_long/2); + false -> next(Req2, State2, 501) + end + end. + +uri_too_long(Req, State) -> + expect(Req, State, uri_too_long, false, fun allowed_methods/2, 414). + +%% allowed_methods/2 should return a list of binary methods. +allowed_methods(Req, State=#state{method=Method}) -> + case call(Req, State, allowed_methods) of + no_call when Method =:= <<"HEAD">>; Method =:= <<"GET">> -> + next(Req, State, fun malformed_request/2); + no_call when Method =:= <<"OPTIONS">> -> + next(Req, State#state{allowed_methods= + [<<"HEAD">>, <<"GET">>, <<"OPTIONS">>]}, + fun malformed_request/2); + no_call -> + method_not_allowed(Req, State, + [<<"HEAD">>, <<"GET">>, <<"OPTIONS">>]); + {stop, Req2, State2} -> + terminate(Req2, State2); + {Switch, Req2, State2} when element(1, Switch) =:= switch_handler -> + switch_handler(Switch, Req2, State2); + {List, Req2, State2} -> + case lists:member(Method, List) of + true when Method =:= <<"OPTIONS">> -> + next(Req2, State2#state{allowed_methods=List}, + fun malformed_request/2); + true -> + next(Req2, State2, fun malformed_request/2); + false -> + method_not_allowed(Req2, State2, List) + end + end. + +method_not_allowed(Req, State, []) -> + Req2 = cowboy_req:set_resp_header(<<"allow">>, <<>>, Req), + respond(Req2, State, 405); +method_not_allowed(Req, State, Methods) -> + << ", ", Allow/binary >> = << << ", ", M/binary >> || M <- Methods >>, + Req2 = cowboy_req:set_resp_header(<<"allow">>, Allow, Req), + respond(Req2, State, 405). + +malformed_request(Req, State) -> + expect(Req, State, malformed_request, false, fun is_authorized/2, 400). + +%% is_authorized/2 should return true or {false, WwwAuthenticateHeader}. +is_authorized(Req, State) -> + case call(Req, State, is_authorized) of + no_call -> + forbidden(Req, State); + {stop, Req2, State2} -> + terminate(Req2, State2); + {Switch, Req2, State2} when element(1, Switch) =:= switch_handler -> + switch_handler(Switch, Req2, State2); + {true, Req2, State2} -> + forbidden(Req2, State2); + {{false, AuthHead}, Req2, State2} -> + Req3 = cowboy_req:set_resp_header( + <<"www-authenticate">>, AuthHead, Req2), + respond(Req3, State2, 401) + end. + +forbidden(Req, State) -> + expect(Req, State, forbidden, false, fun rate_limited/2, 403). + +rate_limited(Req, State) -> + case call(Req, State, rate_limited) of + no_call -> + valid_content_headers(Req, State); + {stop, Req2, State2} -> + terminate(Req2, State2); + {Switch, Req2, State2} when element(1, Switch) =:= switch_handler -> + switch_handler(Switch, Req2, State2); + {false, Req2, State2} -> + valid_content_headers(Req2, State2); + {{true, RetryAfter0}, Req2, State2} -> + RetryAfter = if + is_integer(RetryAfter0), RetryAfter0 >= 0 -> + integer_to_binary(RetryAfter0); + is_tuple(RetryAfter0) -> + cowboy_clock:rfc1123(RetryAfter0) + end, + Req3 = cowboy_req:set_resp_header(<<"retry-after">>, RetryAfter, Req2), + respond(Req3, State2, 429) + end. + +valid_content_headers(Req, State) -> + expect(Req, State, valid_content_headers, true, + fun valid_entity_length/2, 501). + +valid_entity_length(Req, State) -> + expect(Req, State, valid_entity_length, true, fun options/2, 413). + +%% If you need to add additional headers to the response at this point, +%% you should do it directly in the options/2 call using set_resp_headers. +options(Req, State=#state{allowed_methods=Methods, method= <<"OPTIONS">>}) -> + case call(Req, State, options) of + no_call when Methods =:= [] -> + Req2 = cowboy_req:set_resp_header(<<"allow">>, <<>>, Req), + respond(Req2, State, 200); + no_call -> + << ", ", Allow/binary >> + = << << ", ", M/binary >> || M <- Methods >>, + Req2 = cowboy_req:set_resp_header(<<"allow">>, Allow, Req), + respond(Req2, State, 200); + {stop, Req2, State2} -> + terminate(Req2, State2); + {Switch, Req2, State2} when element(1, Switch) =:= switch_handler -> + switch_handler(Switch, Req2, State2); + {ok, Req2, State2} -> + respond(Req2, State2, 200) + end; +options(Req, State) -> + content_types_provided(Req, State). + +%% content_types_provided/2 should return a list of content types and their +%% associated callback function as a tuple: {{Type, SubType, Params}, Fun}. +%% Type and SubType are the media type as binary. Params is a list of +%% Key/Value tuple, with Key and Value a binary. Fun is the name of the +%% callback that will be used to return the content of the response. It is +%% given as an atom. +%% +%% An example of such return value would be: +%% {{<<"text">>, <<"html">>, []}, to_html} +%% +%% Note that it is also possible to return a binary content type that will +%% then be parsed by Cowboy. However note that while this may make your +%% resources a little more readable, this is a lot less efficient. +%% +%% An example of such return value would be: +%% {<<"text/html">>, to_html} +content_types_provided(Req, State) -> + case call(Req, State, content_types_provided) of + no_call -> + State2 = State#state{ + content_types_p=[{{<<"text">>, <<"html">>, '*'}, to_html}]}, + try cowboy_req:parse_header(<<"accept">>, Req) of + undefined -> + languages_provided( + Req#{media_type => {<<"text">>, <<"html">>, []}}, + State2#state{content_type_a={{<<"text">>, <<"html">>, []}, to_html}}); + Accept -> + choose_media_type(Req, State2, prioritize_accept(Accept)) + catch _:_ -> + respond(Req, State2, 400) + end; + {stop, Req2, State2} -> + terminate(Req2, State2); + {Switch, Req2, State2} when element(1, Switch) =:= switch_handler -> + switch_handler(Switch, Req2, State2); + {[], Req2, State2} -> + not_acceptable(Req2, State2); + {CTP, Req2, State2} -> + CTP2 = [normalize_content_types(P) || P <- CTP], + State3 = State2#state{content_types_p=CTP2}, + try cowboy_req:parse_header(<<"accept">>, Req2) of + undefined -> + {PMT0, _Fun} = HeadCTP = hd(CTP2), + %% We replace the wildcard by an empty list of parameters. + PMT = case PMT0 of + {Type, SubType, '*'} -> {Type, SubType, []}; + _ -> PMT0 + end, + languages_provided( + Req2#{media_type => PMT}, + State3#state{content_type_a=HeadCTP}); + Accept -> + choose_media_type(Req2, State3, prioritize_accept(Accept)) + catch _:_ -> + respond(Req2, State3, 400) + end + end. + +normalize_content_types({ContentType, Callback}) + when is_binary(ContentType) -> + {cow_http_hd:parse_content_type(ContentType), Callback}; +normalize_content_types(Normalized) -> + Normalized. + +prioritize_accept(Accept) -> + lists:sort( + fun ({MediaTypeA, Quality, _AcceptParamsA}, + {MediaTypeB, Quality, _AcceptParamsB}) -> + %% Same quality, check precedence in more details. + prioritize_mediatype(MediaTypeA, MediaTypeB); + ({_MediaTypeA, QualityA, _AcceptParamsA}, + {_MediaTypeB, QualityB, _AcceptParamsB}) -> + %% Just compare the quality. + QualityA > QualityB + end, Accept). + +%% Media ranges can be overridden by more specific media ranges or +%% specific media types. If more than one media range applies to a given +%% type, the most specific reference has precedence. +%% +%% We always choose B over A when we can't decide between the two. +prioritize_mediatype({TypeA, SubTypeA, ParamsA}, {TypeB, SubTypeB, ParamsB}) -> + case TypeB of + TypeA -> + case SubTypeB of + SubTypeA -> length(ParamsA) > length(ParamsB); + <<"*">> -> true; + _Any -> false + end; + <<"*">> -> true; + _Any -> false + end. + +%% Ignoring the rare AcceptParams. Not sure what should be done about them. +choose_media_type(Req, State, []) -> + not_acceptable(Req, State); +choose_media_type(Req, State=#state{content_types_p=CTP}, + [MediaType|Tail]) -> + match_media_type(Req, State, Tail, CTP, MediaType). + +match_media_type(Req, State, Accept, [], _MediaType) -> + choose_media_type(Req, State, Accept); +match_media_type(Req, State, Accept, CTP, + MediaType = {{<<"*">>, <<"*">>, _Params_A}, _QA, _APA}) -> + match_media_type_params(Req, State, Accept, CTP, MediaType); +match_media_type(Req, State, Accept, + CTP = [{{Type, SubType_P, _PP}, _Fun}|_Tail], + MediaType = {{Type, SubType_A, _PA}, _QA, _APA}) + when SubType_P =:= SubType_A; SubType_A =:= <<"*">> -> + match_media_type_params(Req, State, Accept, CTP, MediaType); +match_media_type(Req, State, Accept, [_Any|Tail], MediaType) -> + match_media_type(Req, State, Accept, Tail, MediaType). + +match_media_type_params(Req, State, Accept, + [Provided = {{TP, STP, '*'}, _Fun}|Tail], + MediaType = {{TA, _STA, Params_A0}, _QA, _APA}) -> + case lists:keytake(<<"charset">>, 1, Params_A0) of + {value, {_, Charset}, Params_A} when TA =:= <<"text">> -> + %% When we match against a wildcard, the media type is text + %% and has a charset parameter, we call charsets_provided + %% and check that the charset is provided. If the callback + %% is not exported, we accept inconditionally but ignore + %% the given charset so as to not send a wrong value back. + case call(Req, State, charsets_provided) of + no_call -> + languages_provided(Req#{media_type => {TP, STP, Params_A0}}, + State#state{content_type_a=Provided}); + {stop, Req2, State2} -> + terminate(Req2, State2); + {Switch, Req2, State2} when element(1, Switch) =:= switch_handler -> + switch_handler(Switch, Req2, State2); + {CP, Req2, State2} -> + State3 = State2#state{charsets_p=CP}, + case lists:member(Charset, CP) of + false -> + match_media_type(Req2, State3, Accept, Tail, MediaType); + true -> + languages_provided(Req2#{media_type => {TP, STP, Params_A}}, + State3#state{content_type_a=Provided, + charset_a=Charset}) + end + end; + _ -> + languages_provided(Req#{media_type => {TP, STP, Params_A0}}, + State#state{content_type_a=Provided}) + end; +match_media_type_params(Req, State, Accept, + [Provided = {PMT = {TP, STP, Params_P0}, Fun}|Tail], + MediaType = {{_TA, _STA, Params_A}, _QA, _APA}) -> + case lists:sort(Params_P0) =:= lists:sort(Params_A) of + true when TP =:= <<"text">> -> + %% When a charset was provided explicitly in both the charset header + %% and the media types provided and the negotiation is successful, + %% we keep the charset and don't call charsets_provided. This only + %% applies to text media types, however. + {Charset, Params_P} = case lists:keytake(<<"charset">>, 1, Params_P0) of + false -> {undefined, Params_P0}; + {value, {_, Charset0}, Params_P1} -> {Charset0, Params_P1} + end, + languages_provided(Req#{media_type => {TP, STP, Params_P}}, + State#state{content_type_a={{TP, STP, Params_P}, Fun}, + charset_a=Charset}); + true -> + languages_provided(Req#{media_type => PMT}, + State#state{content_type_a=Provided}); + false -> + match_media_type(Req, State, Accept, Tail, MediaType) + end. + +%% languages_provided should return a list of binary values indicating +%% which languages are accepted by the resource. +%% +%% @todo I suppose we should also ask the resource if it wants to +%% set a language itself or if it wants it to be automatically chosen. +languages_provided(Req, State) -> + case call(Req, State, languages_provided) of + no_call -> + charsets_provided(Req, State); + {stop, Req2, State2} -> + terminate(Req2, State2); + {Switch, Req2, State2} when element(1, Switch) =:= switch_handler -> + switch_handler(Switch, Req2, State2); + {[], Req2, State2} -> + not_acceptable(Req2, State2); + {LP, Req2, State2} -> + State3 = State2#state{languages_p=LP}, + case cowboy_req:parse_header(<<"accept-language">>, Req2) of + undefined -> + set_language(Req2, State3#state{language_a=hd(LP)}); + AcceptLanguage -> + AcceptLanguage2 = prioritize_languages(AcceptLanguage), + choose_language(Req2, State3, AcceptLanguage2) + end + end. + +%% A language-range matches a language-tag if it exactly equals the tag, +%% or if it exactly equals a prefix of the tag such that the first tag +%% character following the prefix is "-". The special range "*", if +%% present in the Accept-Language field, matches every tag not matched +%% by any other range present in the Accept-Language field. +%% +%% @todo The last sentence probably means we should always put '*' +%% at the end of the list. +prioritize_languages(AcceptLanguages) -> + lists:sort( + fun ({_TagA, QualityA}, {_TagB, QualityB}) -> + QualityA > QualityB + end, AcceptLanguages). + +choose_language(Req, State, []) -> + not_acceptable(Req, State); +choose_language(Req, State=#state{languages_p=LP}, [Language|Tail]) -> + match_language(Req, State, Tail, LP, Language). + +match_language(Req, State, Accept, [], _Language) -> + choose_language(Req, State, Accept); +match_language(Req, State, _Accept, [Provided|_Tail], {'*', _Quality}) -> + set_language(Req, State#state{language_a=Provided}); +match_language(Req, State, _Accept, [Provided|_Tail], {Provided, _Quality}) -> + set_language(Req, State#state{language_a=Provided}); +match_language(Req, State, Accept, [Provided|Tail], + Language = {Tag, _Quality}) -> + Length = byte_size(Tag), + case Provided of + << Tag:Length/binary, $-, _Any/bits >> -> + set_language(Req, State#state{language_a=Provided}); + _Any -> + match_language(Req, State, Accept, Tail, Language) + end. + +set_language(Req, State=#state{language_a=Language}) -> + Req2 = cowboy_req:set_resp_header(<<"content-language">>, Language, Req), + charsets_provided(Req2#{language => Language}, State). + +%% charsets_provided should return a list of binary values indicating +%% which charsets are accepted by the resource. +%% +%% A charset may have been selected while negotiating the accept header. +%% There's no need to select one again. +charsets_provided(Req, State=#state{charset_a=Charset}) + when Charset =/= undefined -> + set_content_type(Req, State); +%% If charsets_p is defined, use it instead of calling charsets_provided +%% again. We also call this clause during normal execution to avoid +%% duplicating code. +charsets_provided(Req, State=#state{charsets_p=[]}) -> + not_acceptable(Req, State); +charsets_provided(Req, State=#state{charsets_p=CP}) + when CP =/= undefined -> + case cowboy_req:parse_header(<<"accept-charset">>, Req) of + undefined -> + set_content_type(Req, State#state{charset_a=hd(CP)}); + AcceptCharset0 -> + AcceptCharset = prioritize_charsets(AcceptCharset0), + choose_charset(Req, State, AcceptCharset) + end; +charsets_provided(Req, State) -> + case call(Req, State, charsets_provided) of + no_call -> + set_content_type(Req, State); + {stop, Req2, State2} -> + terminate(Req2, State2); + {Switch, Req2, State2} when element(1, Switch) =:= switch_handler -> + switch_handler(Switch, Req2, State2); + {CP, Req2, State2} -> + charsets_provided(Req2, State2#state{charsets_p=CP}) + end. + +prioritize_charsets(AcceptCharsets) -> + lists:sort( + fun ({_CharsetA, QualityA}, {_CharsetB, QualityB}) -> + QualityA > QualityB + end, AcceptCharsets). + +choose_charset(Req, State, []) -> + not_acceptable(Req, State); +%% A q-value of 0 means not acceptable. +choose_charset(Req, State, [{_, 0}|Tail]) -> + choose_charset(Req, State, Tail); +choose_charset(Req, State=#state{charsets_p=CP}, [Charset|Tail]) -> + match_charset(Req, State, Tail, CP, Charset). + +match_charset(Req, State, Accept, [], _Charset) -> + choose_charset(Req, State, Accept); +match_charset(Req, State, _Accept, [Provided|_], {<<"*">>, _}) -> + set_content_type(Req, State#state{charset_a=Provided}); +match_charset(Req, State, _Accept, [Provided|_], {Provided, _}) -> + set_content_type(Req, State#state{charset_a=Provided}); +match_charset(Req, State, Accept, [_|Tail], Charset) -> + match_charset(Req, State, Accept, Tail, Charset). + +set_content_type(Req, State=#state{ + content_type_a={{Type, SubType, Params}, _Fun}, + charset_a=Charset}) -> + ParamsBin = set_content_type_build_params(Params, []), + ContentType = [Type, <<"/">>, SubType, ParamsBin], + ContentType2 = case {Type, Charset} of + {<<"text">>, Charset} when Charset =/= undefined -> + [ContentType, <<"; charset=">>, Charset]; + _ -> + ContentType + end, + Req2 = cowboy_req:set_resp_header(<<"content-type">>, ContentType2, Req), + encodings_provided(Req2#{charset => Charset}, State). + +set_content_type_build_params('*', []) -> + <<>>; +set_content_type_build_params([], []) -> + <<>>; +set_content_type_build_params([], Acc) -> + lists:reverse(Acc); +set_content_type_build_params([{Attr, Value}|Tail], Acc) -> + set_content_type_build_params(Tail, [[Attr, <<"=">>, Value], <<";">>|Acc]). + +%% @todo Match for identity as we provide nothing else for now. +%% @todo Don't forget to set the Content-Encoding header when we reply a body +%% and the found encoding is something other than identity. +encodings_provided(Req, State) -> + ranges_provided(Req, State). + +not_acceptable(Req, State) -> + respond(Req, State, 406). + +ranges_provided(Req, State) -> + case call(Req, State, ranges_provided) of + no_call -> + variances(Req, State); + {stop, Req2, State2} -> + terminate(Req2, State2); + {Switch, Req2, State2} when element(1, Switch) =:= switch_handler -> + switch_handler(Switch, Req2, State2); + {[], Req2, State2} -> + Req3 = cowboy_req:set_resp_header(<<"accept-ranges">>, <<"none">>, Req2), + variances(Req3, State2#state{ranges_a=[]}); + {RP, Req2, State2} -> + <<", ", AcceptRanges/binary>> = <<<<", ", R/binary>> || {R, _} <- RP>>, + Req3 = cowboy_req:set_resp_header(<<"accept-ranges">>, AcceptRanges, Req2), + variances(Req3, State2#state{ranges_a=RP}) + end. + +%% variances/2 should return a list of headers that will be added +%% to the Vary response header. The Accept, Accept-Language, +%% Accept-Charset and Accept-Encoding headers do not need to be +%% specified. +%% +%% @todo Do Accept-Encoding too when we handle it. +%% @todo Does the order matter? +variances(Req, State=#state{content_types_p=CTP, + languages_p=LP, charsets_p=CP}) -> + Variances = case CTP of + [] -> []; + [_] -> []; + [_|_] -> [<<"accept">>] + end, + Variances2 = case LP of + [] -> Variances; + [_] -> Variances; + [_|_] -> [<<"accept-language">>|Variances] + end, + Variances3 = case CP of + undefined -> Variances2; + [] -> Variances2; + [_] -> Variances2; + [_|_] -> [<<"accept-charset">>|Variances2] + end, + try variances(Req, State, Variances3) of + {Variances4, Req2, State2} -> + case [[<<", ">>, V] || V <- Variances4] of + [] -> + resource_exists(Req2, State2); + [[<<", ">>, H]|Variances5] -> + Req3 = cowboy_req:set_resp_header( + <<"vary">>, [H|Variances5], Req2), + resource_exists(Req3, State2) + end + catch Class:Reason:Stacktrace -> + error_terminate(Req, State, Class, Reason, Stacktrace) + end. + +variances(Req, State, Variances) -> + case unsafe_call(Req, State, variances) of + no_call -> + {Variances, Req, State}; + {HandlerVariances, Req2, State2} -> + {Variances ++ HandlerVariances, Req2, State2} + end. + +resource_exists(Req, State) -> + expect(Req, State, resource_exists, true, + fun if_match_exists/2, fun if_match_must_not_exist/2). + +if_match_exists(Req, State) -> + State2 = State#state{exists=true}, + case cowboy_req:parse_header(<<"if-match">>, Req) of + undefined -> + if_unmodified_since_exists(Req, State2); + '*' -> + if_unmodified_since_exists(Req, State2); + ETagsList -> + if_match(Req, State2, ETagsList) + end. + +if_match(Req, State, EtagsList) -> + try generate_etag(Req, State) of + %% Strong Etag comparison: weak Etag never matches. + {{weak, _}, Req2, State2} -> + precondition_failed(Req2, State2); + {Etag, Req2, State2} -> + case lists:member(Etag, EtagsList) of + true -> if_none_match_exists(Req2, State2); + %% Etag may be `undefined' which cannot be a member. + false -> precondition_failed(Req2, State2) + end + catch Class:Reason:Stacktrace -> + error_terminate(Req, State, Class, Reason, Stacktrace) + end. + +if_match_must_not_exist(Req, State) -> + case cowboy_req:header(<<"if-match">>, Req) of + undefined -> is_put_to_missing_resource(Req, State); + _ -> precondition_failed(Req, State) + end. + +if_unmodified_since_exists(Req, State) -> + try cowboy_req:parse_header(<<"if-unmodified-since">>, Req) of + undefined -> + if_none_match_exists(Req, State); + IfUnmodifiedSince -> + if_unmodified_since(Req, State, IfUnmodifiedSince) + catch _:_ -> + if_none_match_exists(Req, State) + end. + +%% If LastModified is the atom 'no_call', we continue. +if_unmodified_since(Req, State, IfUnmodifiedSince) -> + try last_modified(Req, State) of + {LastModified, Req2, State2} -> + case LastModified > IfUnmodifiedSince of + true -> precondition_failed(Req2, State2); + false -> if_none_match_exists(Req2, State2) + end + catch Class:Reason:Stacktrace -> + error_terminate(Req, State, Class, Reason, Stacktrace) + end. + +if_none_match_exists(Req, State) -> + case cowboy_req:parse_header(<<"if-none-match">>, Req) of + undefined -> + if_modified_since_exists(Req, State); + '*' -> + precondition_is_head_get(Req, State); + EtagsList -> + if_none_match(Req, State, EtagsList) + end. + +if_none_match(Req, State, EtagsList) -> + try generate_etag(Req, State) of + {Etag, Req2, State2} -> + case Etag of + undefined -> + precondition_failed(Req2, State2); + Etag -> + case is_weak_match(Etag, EtagsList) of + true -> precondition_is_head_get(Req2, State2); + false -> method(Req2, State2) + end + end + catch Class:Reason:Stacktrace -> + error_terminate(Req, State, Class, Reason, Stacktrace) + end. + +%% Weak Etag comparison: only check the opaque tag. +is_weak_match(_, []) -> + false; +is_weak_match({_, Tag}, [{_, Tag}|_]) -> + true; +is_weak_match(Etag, [_|Tail]) -> + is_weak_match(Etag, Tail). + +precondition_is_head_get(Req, State=#state{method=Method}) + when Method =:= <<"HEAD">>; Method =:= <<"GET">> -> + not_modified(Req, State); +precondition_is_head_get(Req, State) -> + precondition_failed(Req, State). + +if_modified_since_exists(Req, State) -> + try cowboy_req:parse_header(<<"if-modified-since">>, Req) of + undefined -> + method(Req, State); + IfModifiedSince -> + if_modified_since_now(Req, State, IfModifiedSince) + catch _:_ -> + method(Req, State) + end. + +if_modified_since_now(Req, State, IfModifiedSince) -> + case IfModifiedSince > erlang:universaltime() of + true -> method(Req, State); + false -> if_modified_since(Req, State, IfModifiedSince) + end. + +if_modified_since(Req, State, IfModifiedSince) -> + try last_modified(Req, State) of + {undefined, Req2, State2} -> + method(Req2, State2); + {LastModified, Req2, State2} -> + case LastModified > IfModifiedSince of + true -> method(Req2, State2); + false -> not_modified(Req2, State2) + end + catch Class:Reason:Stacktrace -> + error_terminate(Req, State, Class, Reason, Stacktrace) + end. + +not_modified(Req, State) -> + Req2 = cowboy_req:delete_resp_header(<<"content-type">>, Req), + try set_resp_etag(Req2, State) of + {Req3, State2} -> + try set_resp_expires(Req3, State2) of + {Req4, State3} -> + respond(Req4, State3, 304) + catch Class:Reason:Stacktrace -> + error_terminate(Req, State2, Class, Reason, Stacktrace) + end + catch Class:Reason:Stacktrace -> + error_terminate(Req, State, Class, Reason, Stacktrace) + end. + +precondition_failed(Req, State) -> + respond(Req, State, 412). + +is_put_to_missing_resource(Req, State=#state{method= <<"PUT">>}) -> + moved_permanently(Req, State, fun is_conflict/2); +is_put_to_missing_resource(Req, State) -> + previously_existed(Req, State). + +%% moved_permanently/2 should return either false or {true, Location} +%% with Location the full new URI of the resource. +moved_permanently(Req, State, OnFalse) -> + case call(Req, State, moved_permanently) of + {{true, Location}, Req2, State2} -> + Req3 = cowboy_req:set_resp_header( + <<"location">>, Location, Req2), + respond(Req3, State2, 301); + {false, Req2, State2} -> + OnFalse(Req2, State2); + {stop, Req2, State2} -> + terminate(Req2, State2); + {Switch, Req2, State2} when element(1, Switch) =:= switch_handler -> + switch_handler(Switch, Req2, State2); + no_call -> + OnFalse(Req, State) + end. + +previously_existed(Req, State) -> + expect(Req, State, previously_existed, false, + fun (R, S) -> is_post_to_missing_resource(R, S, 404) end, + fun (R, S) -> moved_permanently(R, S, fun moved_temporarily/2) end). + +%% moved_temporarily/2 should return either false or {true, Location} +%% with Location the full new URI of the resource. +moved_temporarily(Req, State) -> + case call(Req, State, moved_temporarily) of + {{true, Location}, Req2, State2} -> + Req3 = cowboy_req:set_resp_header( + <<"location">>, Location, Req2), + respond(Req3, State2, 307); + {false, Req2, State2} -> + is_post_to_missing_resource(Req2, State2, 410); + {stop, Req2, State2} -> + terminate(Req2, State2); + {Switch, Req2, State2} when element(1, Switch) =:= switch_handler -> + switch_handler(Switch, Req2, State2); + no_call -> + is_post_to_missing_resource(Req, State, 410) + end. + +is_post_to_missing_resource(Req, State=#state{method= <<"POST">>}, OnFalse) -> + allow_missing_post(Req, State, OnFalse); +is_post_to_missing_resource(Req, State, OnFalse) -> + respond(Req, State, OnFalse). + +allow_missing_post(Req, State, OnFalse) -> + expect(Req, State, allow_missing_post, true, fun accept_resource/2, OnFalse). + +method(Req, State=#state{method= <<"DELETE">>}) -> + delete_resource(Req, State); +method(Req, State=#state{method= <<"PUT">>}) -> + is_conflict(Req, State); +method(Req, State=#state{method=Method}) + when Method =:= <<"POST">>; Method =:= <<"PATCH">> -> + accept_resource(Req, State); +method(Req, State=#state{method=Method}) + when Method =:= <<"GET">>; Method =:= <<"HEAD">> -> + set_resp_body_etag(Req, State); +method(Req, State) -> + multiple_choices(Req, State). + +%% delete_resource/2 should start deleting the resource and return. +delete_resource(Req, State) -> + expect(Req, State, delete_resource, false, 500, fun delete_completed/2). + +%% delete_completed/2 indicates whether the resource has been deleted yet. +delete_completed(Req, State) -> + expect(Req, State, delete_completed, true, fun has_resp_body/2, 202). + +is_conflict(Req, State) -> + expect(Req, State, is_conflict, false, fun accept_resource/2, 409). + +%% content_types_accepted should return a list of media types and their +%% associated callback functions in the same format as content_types_provided. +%% +%% The callback will then be called and is expected to process the content +%% pushed to the resource in the request body. +%% +%% content_types_accepted SHOULD return a different list +%% for each HTTP method. +accept_resource(Req, State) -> + case call(Req, State, content_types_accepted) of + no_call -> + respond(Req, State, 415); + {stop, Req2, State2} -> + terminate(Req2, State2); + {Switch, Req2, State2} when element(1, Switch) =:= switch_handler -> + switch_handler(Switch, Req2, State2); + {CTA, Req2, State2} -> + CTA2 = [normalize_content_types(P) || P <- CTA], + try cowboy_req:parse_header(<<"content-type">>, Req2) of + %% We do not match against the boundary parameter for multipart. + {Type = <<"multipart">>, SubType, Params} -> + ContentType = {Type, SubType, lists:keydelete(<<"boundary">>, 1, Params)}, + choose_content_type(Req2, State2, ContentType, CTA2); + ContentType -> + choose_content_type(Req2, State2, ContentType, CTA2) + catch _:_ -> + respond(Req2, State2, 415) + end + end. + +%% The special content type '*' will always match. It can be used as a +%% catch-all content type for accepting any kind of request content. +%% Note that because it will always match, it should be the last of the +%% list of content types, otherwise it'll shadow the ones following. +choose_content_type(Req, State, _ContentType, []) -> + respond(Req, State, 415); +choose_content_type(Req, State, ContentType, [{Accepted, Fun}|_Tail]) + when Accepted =:= '*'; Accepted =:= ContentType -> + process_content_type(Req, State, Fun); +%% The special parameter '*' will always match any kind of content type +%% parameters. +%% Note that because it will always match, it should be the last of the +%% list for specific content type, otherwise it'll shadow the ones following. +choose_content_type(Req, State, {Type, SubType, Param}, + [{{Type, SubType, AcceptedParam}, Fun}|_Tail]) + when AcceptedParam =:= '*'; AcceptedParam =:= Param -> + process_content_type(Req, State, Fun); +choose_content_type(Req, State, ContentType, [_Any|Tail]) -> + choose_content_type(Req, State, ContentType, Tail). + +process_content_type(Req, State=#state{method=Method, exists=Exists}, Fun) -> + try case call(Req, State, Fun) of + {stop, Req2, State2} -> + terminate(Req2, State2); + {Switch, Req2, State2} when element(1, Switch) =:= switch_handler -> + switch_handler(Switch, Req2, State2); + {true, Req2, State2} when Exists -> + next(Req2, State2, fun has_resp_body/2); + {true, Req2, State2} -> + next(Req2, State2, fun maybe_created/2); + {false, Req2, State2} -> + respond(Req2, State2, 400); + {{created, ResURL}, Req2, State2} when Method =:= <<"POST">> -> + Req3 = cowboy_req:set_resp_header( + <<"location">>, ResURL, Req2), + respond(Req3, State2, 201); + {{see_other, ResURL}, Req2, State2} when Method =:= <<"POST">> -> + Req3 = cowboy_req:set_resp_header( + <<"location">>, ResURL, Req2), + respond(Req3, State2, 303); + {{true, ResURL}, Req2, State2} when Method =:= <<"POST">> -> + Req3 = cowboy_req:set_resp_header( + <<"location">>, ResURL, Req2), + if + Exists -> respond(Req3, State2, 303); + true -> respond(Req3, State2, 201) + end + end catch Class:Reason = {case_clause, no_call}:Stacktrace -> + error_terminate(Req, State, Class, Reason, Stacktrace) + end. + +%% If PUT was used then the resource has been created at the current URL. +%% Otherwise, if a location header has been set then the resource has been +%% created at a new URL. If not, send a 200 or 204 as expected from a +%% POST or PATCH request. +maybe_created(Req, State=#state{method= <<"PUT">>}) -> + respond(Req, State, 201); +maybe_created(Req, State) -> + case cowboy_req:has_resp_header(<<"location">>, Req) of + true -> respond(Req, State, 201); + false -> has_resp_body(Req, State) + end. + +has_resp_body(Req, State) -> + case cowboy_req:has_resp_body(Req) of + true -> multiple_choices(Req, State); + false -> respond(Req, State, 204) + end. + +%% Set the Etag header if any for the response provided. +set_resp_body_etag(Req, State) -> + try set_resp_etag(Req, State) of + {Req2, State2} -> + set_resp_body_last_modified(Req2, State2) + catch Class:Reason:Stacktrace -> + error_terminate(Req, State, Class, Reason, Stacktrace) + end. + +%% Set the Last-Modified header if any for the response provided. +set_resp_body_last_modified(Req, State) -> + try last_modified(Req, State) of + {LastModified, Req2, State2} -> + case LastModified of + LastModified when is_atom(LastModified) -> + set_resp_body_expires(Req2, State2); + LastModified -> + LastModifiedBin = cowboy_clock:rfc1123(LastModified), + Req3 = cowboy_req:set_resp_header( + <<"last-modified">>, LastModifiedBin, Req2), + set_resp_body_expires(Req3, State2) + end + catch Class:Reason:Stacktrace -> + error_terminate(Req, State, Class, Reason, Stacktrace) + end. + +%% Set the Expires header if any for the response provided. +set_resp_body_expires(Req, State) -> + try set_resp_expires(Req, State) of + {Req2, State2} -> + if_range(Req2, State2) + catch Class:Reason:Stacktrace -> + error_terminate(Req, State, Class, Reason, Stacktrace) + end. + +%% When both the if-range and range headers are set, we perform +%% a strong comparison. If it fails, we send a full response. +if_range(Req=#{headers := #{<<"if-range">> := _, <<"range">> := _}}, + State=#state{etag=Etag}) -> + try cowboy_req:parse_header(<<"if-range">>, Req) of + %% Strong etag comparison is an exact match with the generate_etag result. + Etag={strong, _} -> + range(Req, State); + %% We cannot do a strong date comparison because we have + %% no way of knowing whether the representation changed + %% twice during the second covered by the presented + %% validator. (RFC7232 2.2.2) + _ -> + set_resp_body(Req, State) + catch _:_ -> + set_resp_body(Req, State) + end; +if_range(Req, State) -> + range(Req, State). + +range(Req, State=#state{ranges_a=[]}) -> + set_resp_body(Req, State); +range(Req, State) -> + try cowboy_req:parse_header(<<"range">>, Req) of + undefined -> + set_resp_body(Req, State); + %% @todo Maybe change parse_header to return <<"bytes">> in 3.0. + {bytes, BytesRange} -> + choose_range(Req, State, {<<"bytes">>, BytesRange}); + Range -> + choose_range(Req, State, Range) + catch _:_ -> + %% We send a 416 response back when we can't parse the + %% range header at all. I'm not sure this is the right + %% way to go but at least this can help clients identify + %% what went wrong when their range requests never work. + range_not_satisfiable(Req, State, undefined) + end. + +choose_range(Req, State=#state{ranges_a=RangesAccepted}, Range={RangeUnit, _}) -> + case lists:keyfind(RangeUnit, 1, RangesAccepted) of + {_, Callback} -> + %% We pass the selected range onward in the Req. + range_satisfiable(Req#{range => Range}, State, Callback); + false -> + set_resp_body(Req, State) + end. + +range_satisfiable(Req, State, Callback) -> + case call(Req, State, range_satisfiable) of + no_call -> + set_ranged_body(Req, State, Callback); + {stop, Req2, State2} -> + terminate(Req2, State2); + {Switch, Req2, State2} when element(1, Switch) =:= switch_handler -> + switch_handler(Switch, Req2, State2); + {true, Req2, State2} -> + set_ranged_body(Req2, State2, Callback); + {false, Req2, State2} -> + range_not_satisfiable(Req2, State2, undefined); + {{false, Int}, Req2, State2} when is_integer(Int) -> + range_not_satisfiable(Req2, State2, [<<"*/">>, integer_to_binary(Int)]); + {{false, Iodata}, Req2, State2} when is_binary(Iodata); is_list(Iodata) -> + range_not_satisfiable(Req2, State2, Iodata) + end. + +%% When the callback selected is 'auto' and the range unit +%% is bytes, we call the normal provide callback and split +%% the content automatically. +set_ranged_body(Req=#{range := {<<"bytes">>, _}}, State, auto) -> + set_ranged_body_auto(Req, State); +set_ranged_body(Req, State, Callback) -> + set_ranged_body_callback(Req, State, Callback). + +set_ranged_body_auto(Req, State=#state{handler=Handler, content_type_a={_, Callback}}) -> + try case call(Req, State, Callback) of + {stop, Req2, State2} -> + terminate(Req2, State2); + {Switch, Req2, State2} when element(1, Switch) =:= switch_handler -> + switch_handler(Switch, Req2, State2); + {Body, Req2, State2} -> + maybe_set_ranged_body_auto(Req2, State2, Body) + end catch Class:{case_clause, no_call}:Stacktrace -> + error_terminate(Req, State, Class, {error, {missing_callback, {Handler, Callback, 2}}, + 'A callback specified in content_types_provided/2 is not exported.'}, + Stacktrace) + end. + +maybe_set_ranged_body_auto(Req=#{range := {_, Ranges}}, State, Body) -> + Size = case Body of + {sendfile, _, Bytes, _} -> Bytes; + _ -> iolist_size(Body) + end, + Checks = [case Range of + {From, infinity} -> From < Size; + {From, To} -> (From < Size) andalso (From =< To) andalso (To =< Size); + Neg -> (Neg =/= 0) andalso (-Neg < Size) + end || Range <- Ranges], + case lists:usort(Checks) of + [true] -> set_ranged_body_auto(Req, State, Body); + _ -> range_not_satisfiable(Req, State, [<<"*/">>, integer_to_binary(Size)]) + end. + +%% We might also want to have some checks about range order, +%% number of ranges, and perhaps also join ranges that are +%% too close into one contiguous range. Some of these can +%% be done before calling the ProvideCallback. + +set_ranged_body_auto(Req=#{range := {_, Ranges}}, State, Body) -> + Parts = [ranged_partition(Range, Body) || Range <- Ranges], + case Parts of + [OnePart] -> set_one_ranged_body(Req, State, OnePart); + _ when is_tuple(Body) -> send_multipart_ranged_body(Req, State, Parts); + _ -> set_multipart_ranged_body(Req, State, Parts) + end. + +ranged_partition(Range, {sendfile, Offset0, Bytes0, Path}) -> + {From, To, Offset, Bytes} = case Range of + {From0, infinity} -> {From0, Bytes0 - 1, Offset0 + From0, Bytes0 - From0}; + {From0, To0} -> {From0, To0, Offset0 + From0, 1 + To0 - From0}; + Neg -> {Bytes0 + Neg, Bytes0 - 1, Offset0 + Bytes0 + Neg, -Neg} + end, + {{From, To, Bytes0}, {sendfile, Offset, Bytes, Path}}; +ranged_partition(Range, Data0) -> + Total = iolist_size(Data0), + {From, To, Data} = case Range of + {From0, infinity} -> + {_, Data1} = cow_iolists:split(From0, Data0), + {From0, Total - 1, Data1}; + {From0, To0} -> + {_, Data1} = cow_iolists:split(From0, Data0), + {Data2, _} = cow_iolists:split(To0 - From0 + 1, Data1), + {From0, To0, Data2}; + Neg -> + {_, Data1} = cow_iolists:split(Total + Neg, Data0), + {Total + Neg, Total - 1, Data1} + end, + {{From, To, Total}, Data}. + +-ifdef(TEST). +ranged_partition_test_() -> + Tests = [ + %% Sendfile with open-ended range. + {{0, infinity}, {sendfile, 0, 12, "t"}, {{0, 11, 12}, {sendfile, 0, 12, "t"}}}, + {{6, infinity}, {sendfile, 0, 12, "t"}, {{6, 11, 12}, {sendfile, 6, 6, "t"}}}, + {{11, infinity}, {sendfile, 0, 12, "t"}, {{11, 11, 12}, {sendfile, 11, 1, "t"}}}, + %% Sendfile with open-ended range. Sendfile tuple has an offset originally. + {{0, infinity}, {sendfile, 3, 12, "t"}, {{0, 11, 12}, {sendfile, 3, 12, "t"}}}, + {{6, infinity}, {sendfile, 3, 12, "t"}, {{6, 11, 12}, {sendfile, 9, 6, "t"}}}, + {{11, infinity}, {sendfile, 3, 12, "t"}, {{11, 11, 12}, {sendfile, 14, 1, "t"}}}, + %% Sendfile with a specific range. + {{0, 11}, {sendfile, 0, 12, "t"}, {{0, 11, 12}, {sendfile, 0, 12, "t"}}}, + {{6, 11}, {sendfile, 0, 12, "t"}, {{6, 11, 12}, {sendfile, 6, 6, "t"}}}, + {{11, 11}, {sendfile, 0, 12, "t"}, {{11, 11, 12}, {sendfile, 11, 1, "t"}}}, + {{1, 10}, {sendfile, 0, 12, "t"}, {{1, 10, 12}, {sendfile, 1, 10, "t"}}}, + %% Sendfile with a specific range. Sendfile tuple has an offset originally. + {{0, 11}, {sendfile, 3, 12, "t"}, {{0, 11, 12}, {sendfile, 3, 12, "t"}}}, + {{6, 11}, {sendfile, 3, 12, "t"}, {{6, 11, 12}, {sendfile, 9, 6, "t"}}}, + {{11, 11}, {sendfile, 3, 12, "t"}, {{11, 11, 12}, {sendfile, 14, 1, "t"}}}, + {{1, 10}, {sendfile, 3, 12, "t"}, {{1, 10, 12}, {sendfile, 4, 10, "t"}}}, + %% Sendfile with negative range. + {-12, {sendfile, 0, 12, "t"}, {{0, 11, 12}, {sendfile, 0, 12, "t"}}}, + {-6, {sendfile, 0, 12, "t"}, {{6, 11, 12}, {sendfile, 6, 6, "t"}}}, + {-1, {sendfile, 0, 12, "t"}, {{11, 11, 12}, {sendfile, 11, 1, "t"}}}, + %% Sendfile with negative range. Sendfile tuple has an offset originally. + {-12, {sendfile, 3, 12, "t"}, {{0, 11, 12}, {sendfile, 3, 12, "t"}}}, + {-6, {sendfile, 3, 12, "t"}, {{6, 11, 12}, {sendfile, 9, 6, "t"}}}, + {-1, {sendfile, 3, 12, "t"}, {{11, 11, 12}, {sendfile, 14, 1, "t"}}}, + %% Iodata with open-ended range. + {{0, infinity}, <<"Hello world!">>, {{0, 11, 12}, <<"Hello world!">>}}, + {{6, infinity}, <<"Hello world!">>, {{6, 11, 12}, <<"world!">>}}, + {{11, infinity}, <<"Hello world!">>, {{11, 11, 12}, <<"!">>}}, + %% Iodata with a specific range. The resulting data is + %% wrapped in a list because of how cow_iolists:split/2 works. + {{0, 11}, <<"Hello world!">>, {{0, 11, 12}, [<<"Hello world!">>]}}, + {{6, 11}, <<"Hello world!">>, {{6, 11, 12}, [<<"world!">>]}}, + {{11, 11}, <<"Hello world!">>, {{11, 11, 12}, [<<"!">>]}}, + {{1, 10}, <<"Hello world!">>, {{1, 10, 12}, [<<"ello world">>]}}, + %% Iodata with negative range. + {-12, <<"Hello world!">>, {{0, 11, 12}, <<"Hello world!">>}}, + {-6, <<"Hello world!">>, {{6, 11, 12}, <<"world!">>}}, + {-1, <<"Hello world!">>, {{11, 11, 12}, <<"!">>}} + ], + [{iolist_to_binary(io_lib:format("range ~p data ~p", [VR, VD])), + fun() -> R = ranged_partition(VR, VD) end} || {VR, VD, R} <- Tests]. +-endif. + +set_ranged_body_callback(Req, State=#state{handler=Handler}, Callback) -> + try case call(Req, State, Callback) of + {stop, Req2, State2} -> + terminate(Req2, State2); + {Switch, Req2, State2} when element(1, Switch) =:= switch_handler -> + switch_handler(Switch, Req2, State2); + %% When we receive a single range, we send it directly. + {[OneRange], Req2, State2} -> + set_one_ranged_body(Req2, State2, OneRange); + %% When we receive multiple ranges we have to send them as multipart/byteranges. + %% This also applies to non-bytes units. (RFC7233 A) If users don't want to use + %% this for non-bytes units they can always return a single range with a binary + %% content-range information. + {Ranges, Req2, State2} when length(Ranges) > 1 -> + %% We have to check whether there are sendfile tuples in the + %% ranges to be sent. If there are we must use stream_reply. + HasSendfile = [] =/= [true || {_, {sendfile, _, _, _}} <- Ranges], + case HasSendfile of + true -> send_multipart_ranged_body(Req2, State2, Ranges); + false -> set_multipart_ranged_body(Req2, State2, Ranges) + end + end catch Class:{case_clause, no_call}:Stacktrace -> + error_terminate(Req, State, Class, {error, {missing_callback, {Handler, Callback, 2}}, + 'A callback specified in ranges_provided/2 is not exported.'}, + Stacktrace) + end. + +set_one_ranged_body(Req0, State, OneRange) -> + {ContentRange, Body} = prepare_range(Req0, OneRange), + Req1 = cowboy_req:set_resp_header(<<"content-range">>, ContentRange, Req0), + Req = cowboy_req:set_resp_body(Body, Req1), + respond(Req, State, 206). + +set_multipart_ranged_body(Req, State, [FirstRange|MoreRanges]) -> + Boundary = cow_multipart:boundary(), + ContentType = cowboy_req:resp_header(<<"content-type">>, Req), + {FirstContentRange, FirstPartBody} = prepare_range(Req, FirstRange), + FirstPartHead = cow_multipart:first_part(Boundary, [ + {<<"content-type">>, ContentType}, + {<<"content-range">>, FirstContentRange} + ]), + MoreParts = [begin + {NextContentRange, NextPartBody} = prepare_range(Req, NextRange), + NextPartHead = cow_multipart:part(Boundary, [ + {<<"content-type">>, ContentType}, + {<<"content-range">>, NextContentRange} + ]), + [NextPartHead, NextPartBody] + end || NextRange <- MoreRanges], + Body = [FirstPartHead, FirstPartBody, MoreParts, cow_multipart:close(Boundary)], + Req2 = cowboy_req:set_resp_header(<<"content-type">>, + [<<"multipart/byteranges; boundary=">>, Boundary], Req), + Req3 = cowboy_req:set_resp_body(Body, Req2), + respond(Req3, State, 206). + +%% Similar to set_multipart_ranged_body except we have to stream +%% the data because the parts contain sendfile tuples. +send_multipart_ranged_body(Req, State, [FirstRange|MoreRanges]) -> + Boundary = cow_multipart:boundary(), + ContentType = cowboy_req:resp_header(<<"content-type">>, Req), + Req2 = cowboy_req:set_resp_header(<<"content-type">>, + [<<"multipart/byteranges; boundary=">>, Boundary], Req), + Req3 = cowboy_req:stream_reply(206, Req2), + {FirstContentRange, FirstPartBody} = prepare_range(Req, FirstRange), + FirstPartHead = cow_multipart:first_part(Boundary, [ + {<<"content-type">>, ContentType}, + {<<"content-range">>, FirstContentRange} + ]), + cowboy_req:stream_body(FirstPartHead, nofin, Req3), + cowboy_req:stream_body(FirstPartBody, nofin, Req3), + _ = [begin + {NextContentRange, NextPartBody} = prepare_range(Req, NextRange), + NextPartHead = cow_multipart:part(Boundary, [ + {<<"content-type">>, ContentType}, + {<<"content-range">>, NextContentRange} + ]), + cowboy_req:stream_body(NextPartHead, nofin, Req3), + cowboy_req:stream_body(NextPartBody, nofin, Req3), + [NextPartHead, NextPartBody] + end || NextRange <- MoreRanges], + cowboy_req:stream_body(cow_multipart:close(Boundary), fin, Req3), + terminate(Req3, State). + +prepare_range(#{range := {RangeUnit, _}}, {{From, To, Total0}, Body}) -> + Total = case Total0 of + '*' -> <<"*">>; + _ -> integer_to_binary(Total0) + end, + ContentRange = [RangeUnit, $\s, integer_to_binary(From), + $-, integer_to_binary(To), $/, Total], + {ContentRange, Body}; +prepare_range(#{range := {RangeUnit, _}}, {RangeData, Body}) -> + {[RangeUnit, $\s, RangeData], Body}. + +%% We send the content-range header when we can on error. +range_not_satisfiable(Req, State, undefined) -> + respond(Req, State, 416); +range_not_satisfiable(Req0=#{range := {RangeUnit, _}}, State, RangeData) -> + Req = cowboy_req:set_resp_header(<<"content-range">>, + [RangeUnit, $\s, RangeData], Req0), + respond(Req, State, 416). + +%% Set the response headers and call the callback found using +%% content_types_provided/2 to obtain the request body and add +%% it to the response. +set_resp_body(Req, State=#state{handler=Handler, content_type_a={_, Callback}}) -> + try case call(Req, State, Callback) of + {stop, Req2, State2} -> + terminate(Req2, State2); + {Switch, Req2, State2} when element(1, Switch) =:= switch_handler -> + switch_handler(Switch, Req2, State2); + {Body, Req2, State2} -> + Req3 = cowboy_req:set_resp_body(Body, Req2), + multiple_choices(Req3, State2) + end catch Class:{case_clause, no_call}:Stacktrace -> + error_terminate(Req, State, Class, {error, {missing_callback, {Handler, Callback, 2}}, + 'A callback specified in content_types_provided/2 is not exported.'}, + Stacktrace) + end. + +multiple_choices(Req, State) -> + expect(Req, State, multiple_choices, false, 200, 300). + +%% Response utility functions. + +set_resp_etag(Req, State) -> + {Etag, Req2, State2} = generate_etag(Req, State), + case Etag of + undefined -> + {Req2, State2}; + Etag -> + Req3 = cowboy_req:set_resp_header( + <<"etag">>, encode_etag(Etag), Req2), + {Req3, State2} + end. + +-spec encode_etag({strong | weak, binary()}) -> iolist(). +encode_etag({strong, Etag}) -> [$",Etag,$"]; +encode_etag({weak, Etag}) -> ["W/\"",Etag,$"]. + +set_resp_expires(Req, State) -> + {Expires, Req2, State2} = expires(Req, State), + case Expires of + Expires when is_atom(Expires) -> + {Req2, State2}; + Expires when is_binary(Expires) -> + Req3 = cowboy_req:set_resp_header( + <<"expires">>, Expires, Req2), + {Req3, State2}; + Expires -> + ExpiresBin = cowboy_clock:rfc1123(Expires), + Req3 = cowboy_req:set_resp_header( + <<"expires">>, ExpiresBin, Req2), + {Req3, State2} + end. + +%% Info retrieval. No logic. + +generate_etag(Req, State=#state{etag=no_call}) -> + {undefined, Req, State}; +generate_etag(Req, State=#state{etag=undefined}) -> + case unsafe_call(Req, State, generate_etag) of + no_call -> + {undefined, Req, State#state{etag=no_call}}; + {Etag, Req2, State2} when is_binary(Etag) -> + Etag2 = cow_http_hd:parse_etag(Etag), + {Etag2, Req2, State2#state{etag=Etag2}}; + {Etag, Req2, State2} -> + {Etag, Req2, State2#state{etag=Etag}} + end; +generate_etag(Req, State=#state{etag=Etag}) -> + {Etag, Req, State}. + +last_modified(Req, State=#state{last_modified=no_call}) -> + {undefined, Req, State}; +last_modified(Req, State=#state{last_modified=undefined}) -> + case unsafe_call(Req, State, last_modified) of + no_call -> + {undefined, Req, State#state{last_modified=no_call}}; + {LastModified, Req2, State2} -> + {LastModified, Req2, State2#state{last_modified=LastModified}} + end; +last_modified(Req, State=#state{last_modified=LastModified}) -> + {LastModified, Req, State}. + +expires(Req, State=#state{expires=no_call}) -> + {undefined, Req, State}; +expires(Req, State=#state{expires=undefined}) -> + case unsafe_call(Req, State, expires) of + no_call -> + {undefined, Req, State#state{expires=no_call}}; + {Expires, Req2, State2} -> + {Expires, Req2, State2#state{expires=Expires}} + end; +expires(Req, State=#state{expires=Expires}) -> + {Expires, Req, State}. + +%% REST primitives. + +expect(Req, State, Callback, Expected, OnTrue, OnFalse) -> + case call(Req, State, Callback) of + no_call -> + next(Req, State, OnTrue); + {stop, Req2, State2} -> + terminate(Req2, State2); + {Switch, Req2, State2} when element(1, Switch) =:= switch_handler -> + switch_handler(Switch, Req2, State2); + {Expected, Req2, State2} -> + next(Req2, State2, OnTrue); + {_Unexpected, Req2, State2} -> + next(Req2, State2, OnFalse) + end. + +call(Req0, State=#state{handler=Handler, + handler_state=HandlerState0}, Callback) -> + case erlang:function_exported(Handler, Callback, 2) of + true -> + try Handler:Callback(Req0, HandlerState0) of + no_call -> + no_call; + {Result, Req, HandlerState} -> + {Result, Req, State#state{handler_state=HandlerState}} + catch Class:Reason:Stacktrace -> + error_terminate(Req0, State, Class, Reason, Stacktrace) + end; + false -> + no_call + end. + +unsafe_call(Req0, State=#state{handler=Handler, + handler_state=HandlerState0}, Callback) -> + case erlang:function_exported(Handler, Callback, 2) of + false -> + no_call; + true -> + case Handler:Callback(Req0, HandlerState0) of + no_call -> + no_call; + {Result, Req, HandlerState} -> + {Result, Req, State#state{handler_state=HandlerState}} + end + end. + +next(Req, State, Next) when is_function(Next) -> + Next(Req, State); +next(Req, State, StatusCode) when is_integer(StatusCode) -> + respond(Req, State, StatusCode). + +respond(Req0, State, StatusCode) -> + %% We remove the content-type header when there is no body, + %% except when the status code is 200 because it might have + %% been intended (for example sending an empty file). + Req = case cowboy_req:has_resp_body(Req0) of + true when StatusCode =:= 200 -> Req0; + true -> Req0; + false -> cowboy_req:delete_resp_header(<<"content-type">>, Req0) + end, + terminate(cowboy_req:reply(StatusCode, Req), State). + +switch_handler({switch_handler, Mod}, Req, #state{handler_state=HandlerState}) -> + {Mod, Req, HandlerState}; +switch_handler({switch_handler, Mod, Opts}, Req, #state{handler_state=HandlerState}) -> + {Mod, Req, HandlerState, Opts}. + +-spec error_terminate(cowboy_req:req(), #state{}, atom(), any(), any()) -> no_return(). +error_terminate(Req, #state{handler=Handler, handler_state=HandlerState}, Class, Reason, Stacktrace) -> + cowboy_handler:terminate({crash, Class, Reason}, Req, HandlerState, Handler), + erlang:raise(Class, Reason, Stacktrace). + +terminate(Req, #state{handler=Handler, handler_state=HandlerState}) -> + Result = cowboy_handler:terminate(normal, Req, HandlerState, Handler), + {ok, Req, Result}. |