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+%% Copyright (c) 2011, Anthony Ramine <[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.
+
+%% @doc Multipart parser.
+-module(cowboy_multipart).
+
+-type part_parser() :: parser(more(part_result())).
+-type parser(T) :: fun((binary()) -> T).
+-type more(T) :: T | {more, parser(T)}.
+-type part_result() :: headers() | eof.
+-type headers() :: {headers, http_headers(), body_cont()}.
+-type http_headers() :: [{atom() | binary(), binary()}].
+-type body_cont() :: cont(more(body_result())).
+-type cont(T) :: fun(() -> T).
+-type body_result() :: {body, binary(), body_cont()} | end_of_part().
+-type end_of_part() :: {end_of_part, cont(more(part_result()))}.
+-type disposition() :: {binary(), [{binary(), binary()}]}.
+
+-export([parser/1, content_disposition/1]).
+
+-include_lib("eunit/include/eunit.hrl").
+
+%% API.
+
+%% @doc Return a multipart parser for the given boundary.
+-spec parser(binary()) -> part_parser().
+parser(Boundary) when is_binary(Boundary) ->
+ fun (Bin) when is_binary(Bin) -> parse(Bin, Boundary) end.
+
+%% @doc Parse a content disposition.
+%% @todo Parse the MIME header instead of the HTTP one.
+-spec content_disposition(binary()) -> disposition().
+content_disposition(Data) ->
+ cowboy_http:token_ci(Data,
+ fun (_Rest, <<>>) -> {error, badarg};
+ (Rest, Disposition) ->
+ cowboy_http:content_type_params(Rest,
+ fun (Params) -> {Disposition, Params} end, [])
+ end).
+
+%% Internal.
+
+%% @doc Entry point of the multipart parser, skips over the preamble if any.
+-spec parse(binary(), binary()) -> more(part_result()).
+parse(Bin, Boundary) when byte_size(Bin) >= byte_size(Boundary) + 2 ->
+ BoundarySize = byte_size(Boundary),
+ Pattern = pattern(Boundary),
+ case Bin of
+ <<"--", Boundary:BoundarySize/binary, Rest/binary>> ->
+ % Data starts with initial boundary, skip preamble parsing.
+ parse_boundary_tail(Rest, Pattern);
+ _ ->
+ % Parse preamble.
+ skip(Bin, Pattern)
+ end;
+parse(Bin, Boundary) ->
+ % Not enough data to know if the data begins with a boundary.
+ more(Bin, fun (NewBin) -> parse(NewBin, Boundary) end).
+
+-type pattern() :: {binary:cp(), non_neg_integer()}.
+
+%% @doc Return a compiled binary pattern with its size in bytes.
+%% The pattern is the boundary prepended with "\r\n--".
+-spec pattern(binary()) -> pattern().
+pattern(Boundary) ->
+ MatchPattern = <<"\r\n--", Boundary/binary>>,
+ {binary:compile_pattern(MatchPattern), byte_size(MatchPattern)}.
+
+%% @doc Parse remaining characters of a line beginning with the boundary.
+%% If followed by "--", <em>eof</em> is returned and parsing is finished.
+-spec parse_boundary_tail(binary(), pattern()) -> more(part_result()).
+parse_boundary_tail(Bin, Pattern) when byte_size(Bin) >= 2 ->
+ case Bin of
+ <<"--", _Rest/binary>> ->
+ % Boundary is followed by "--", end parsing.
+ eof;
+ _ ->
+ % No dash after boundary, proceed with unknown chars and lwsp
+ % removal.
+ parse_boundary_eol(Bin, Pattern)
+ end;
+parse_boundary_tail(Bin, Pattern) ->
+ % Boundary may be followed by "--", need more data.
+ more(Bin, fun (NewBin) -> parse_boundary_tail(NewBin, Pattern) end).
+
+%% @doc Skip whitespace and unknown chars until CRLF.
+-spec parse_boundary_eol(binary(), pattern()) -> more(part_result()).
+parse_boundary_eol(Bin, Pattern) ->
+ case binary:match(Bin, <<"\r\n">>) of
+ {CrlfStart, _Length} ->
+ % End of line found, remove optional whitespace.
+ <<_:CrlfStart/binary, Rest/binary>> = Bin,
+ Fun = fun (Rest2) -> parse_boundary_crlf(Rest2, Pattern) end,
+ cowboy_http:whitespace(Rest, Fun);
+ nomatch ->
+ % CRLF not found in the given binary.
+ RestStart = max(byte_size(Bin) - 1, 0),
+ <<_:RestStart/binary, Rest/binary>> = Bin,
+ more(Rest, fun (NewBin) -> parse_boundary_eol(NewBin, Pattern) end)
+ end.
+
+-spec parse_boundary_crlf(binary(), pattern()) -> more(part_result()).
+parse_boundary_crlf(<<"\r\n", Rest/binary>>, Pattern) ->
+ % The binary is at least 2 bytes long as this function is only called by
+ % parse_boundary_eol/3 when CRLF has been found so a more tuple will never
+ % be returned from here.
+ parse_headers(Rest, Pattern);
+parse_boundary_crlf(Bin, Pattern) ->
+ % Unspecified behaviour here: RFC 2046 doesn't say what to do when LWSP is
+ % not followed directly by a new line. In this implementation it is
+ % considered part of the boundary so EOL needs to be searched again.
+ parse_boundary_eol(Bin, Pattern).
+
+-spec parse_headers(binary(), pattern()) -> more(part_result()).
+parse_headers(Bin, Pattern) ->
+ parse_headers(Bin, Pattern, []).
+
+-spec parse_headers(binary(), pattern(), http_headers()) -> more(part_result()).
+parse_headers(Bin, Pattern, Acc) ->
+ case erlang:decode_packet(httph_bin, Bin, []) of
+ {ok, {http_header, _, Name, _, Value}, Rest} ->
+ parse_headers(Rest, Pattern, [{Name, Value} | Acc]);
+ {ok, http_eoh, Rest} ->
+ Headers = lists:reverse(Acc),
+ {headers, Headers, fun () -> parse_body(Rest, Pattern) end};
+ {ok, {http_error, _}, _} ->
+ % Skip malformed parts.
+ skip(Bin, Pattern);
+ {more, _} ->
+ more(Bin, fun (NewBin) -> parse_headers(NewBin, Pattern, Acc) end)
+ end.
+
+-spec parse_body(binary(), pattern()) -> more(body_result()).
+parse_body(Bin, Pattern = {P, PSize}) when byte_size(Bin) >= PSize ->
+ case binary:match(Bin, P) of
+ {0, _Length} ->
+ <<_:PSize/binary, Rest/binary>> = Bin,
+ end_of_part(Rest, Pattern);
+ {BoundaryStart, _Length} ->
+ % Boundary found, this is the latest partial body that will be
+ % returned for this part.
+ <<PBody:BoundaryStart/binary, _:PSize/binary, Rest/binary>> = Bin,
+ FResult = end_of_part(Rest, Pattern),
+ {body, PBody, fun () -> FResult end};
+ nomatch ->
+ PartialLength = byte_size(Bin) - PSize + 1,
+ <<PBody:PartialLength/binary, Rest/binary>> = Bin,
+ {body, PBody, fun () -> parse_body(Rest, Pattern) end}
+ end;
+parse_body(Bin, Pattern) ->
+ more(Bin, fun (NewBin) -> parse_body(NewBin, Pattern) end).
+
+-spec end_of_part(binary(), pattern()) -> end_of_part().
+end_of_part(Bin, Pattern) ->
+ {end_of_part, fun () -> parse_boundary_tail(Bin, Pattern) end}.
+
+-spec skip(binary(), pattern()) -> more(part_result()).
+skip(Bin, Pattern = {P, PSize}) ->
+ case binary:match(Bin, P) of
+ {BoundaryStart, _Length} ->
+ % Boundary found, proceed with parsing of the next part.
+ RestStart = BoundaryStart + PSize,
+ <<_:RestStart/binary, Rest/binary>> = Bin,
+ parse_boundary_tail(Rest, Pattern);
+ nomatch ->
+ % Boundary not found, need more data.
+ RestStart = max(byte_size(Bin) - PSize + 1, 0),
+ <<_:RestStart/binary, Rest/binary>> = Bin,
+ more(Rest, fun (NewBin) -> skip(NewBin, Pattern) end)
+ end.
+
+-spec more(binary(), parser(T)) -> {more, parser(T)}.
+more(<<>>, F) ->
+ {more, F};
+more(Bin, InnerF) ->
+ F = fun (NewData) when is_binary(NewData) ->
+ InnerF(<<Bin/binary, NewData/binary>>)
+ end,
+ {more, F}.
+
+%% Tests.
+
+-ifdef(TEST).
+
+multipart_test_() ->
+ %% {Body, Result}
+ Tests = [
+ {<<"--boundary--">>, []},
+ {<<"preamble\r\n--boundary--">>, []},
+ {<<"--boundary--\r\nepilogue">>, []},
+ {<<"\r\n--boundary\r\nA:b\r\nC:d\r\n\r\n\r\n--boundary--">>,
+ [{[{<<"A">>, <<"b">>}, {<<"C">>, <<"d">>}], <<>>}]},
+ {
+ <<
+ "--boundary\r\nX-Name:answer\r\n\r\n42"
+ "\r\n--boundary\r\nServer:Cowboy\r\n\r\nIt rocks!\r\n"
+ "\r\n--boundary--"
+ >>,
+ [
+ {[{<<"X-Name">>, <<"answer">>}], <<"42">>},
+ {[{'Server', <<"Cowboy">>}], <<"It rocks!\r\n">>}
+ ]
+ }
+ ],
+ [{title(V), fun () -> R = acc_multipart(V) end} || {V, R} <- Tests].
+
+acc_multipart(V) ->
+ acc_multipart((parser(<<"boundary">>))(V), []).
+
+acc_multipart({headers, Headers, Cont}, Acc) ->
+ acc_multipart(Cont(), [{Headers, []}|Acc]);
+acc_multipart({body, Body, Cont}, [{Headers, BodyAcc}|Acc]) ->
+ acc_multipart(Cont(), [{Headers, [Body|BodyAcc]}|Acc]);
+acc_multipart({end_of_part, Cont}, [{Headers, BodyAcc}|Acc]) ->
+ Body = list_to_binary(lists:reverse(BodyAcc)),
+ acc_multipart(Cont(), [{Headers, Body}|Acc]);
+acc_multipart(eof, Acc) ->
+ lists:reverse(Acc).
+
+content_disposition_test_() ->
+ %% {Disposition, Result}
+ Tests = [
+ {<<"form-data; name=id">>, {<<"form-data">>, [{<<"name">>, <<"id">>}]}},
+ {<<"inline">>, {<<"inline">>, []}},
+ {<<"attachment; \tfilename=brackets-slides.pdf">>,
+ {<<"attachment">>, [{<<"filename">>, <<"brackets-slides.pdf">>}]}}
+ ],
+ [{title(V), fun () -> R = content_disposition(V) end} || {V, R} <- Tests].
+
+title(Bin) ->
+ Title = lists:foldl(
+ fun ({T, R}, V) -> re:replace(V, T, R, [global]) end,
+ Bin,
+ [{"\t", "\\\\t"}, {"\r", "\\\\r"}, {"\n", "\\\\n"}]
+ ),
+ iolist_to_binary(Title).
+
+-endif.