%% 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).
-export([parser/1]).
-export([content_disposition/1]).
-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() :: [{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()}]}.
-ifdef(TEST).
-include_lib("eunit/include/eunit.hrl").
-endif.
%% 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:params(Rest,
fun (<<>>, Params) -> {Disposition, Params};
(_Rest2, _) -> {error, badarg}
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()}.
-type patterns() :: {pattern(), pattern()}.
%% @doc Return two compiled binary patterns with their sizes in bytes.
%% The boundary pattern is the boundary prepended with "\r\n--".
%% The boundary suffix pattern matches all prefixes of the boundary.
-spec pattern(binary()) -> patterns().
pattern(Boundary) ->
MatchPattern = <<"\r\n--", Boundary/binary>>,
MatchPrefixes = prefixes(MatchPattern),
{{binary:compile_pattern(MatchPattern), byte_size(MatchPattern)},
{binary:compile_pattern(MatchPrefixes), byte_size(MatchPattern)}}.
%% @doc Return all prefixes of a binary string.
%% The list of prefixes includes the full string.
-spec prefixes(binary()) -> [binary()].
prefixes(<<C, Rest/binary>>) ->
prefixes(Rest, <<C>>).
-spec prefixes(binary(), binary()) -> [binary()].
prefixes(<<C, Rest/binary>>, Acc) ->
[Acc|prefixes(Rest, <<Acc/binary, C>>)];
prefixes(<<>>, Acc) ->
[Acc].
%% @doc Test if a boundary is a possble suffix.
%% The patterns are expected to have been returned from `pattern/1`.
-spec suffix_match(binary(), patterns()) -> nomatch | {integer(), integer()}.
suffix_match(Bin, {_Boundary, {Pat, Len}}) ->
Size = byte_size(Bin),
suffix_match(Bin, Pat, Size, max(-Size, -Len)).
-spec suffix_match(binary(), tuple(), non_neg_integer(), 0|neg_integer()) ->
nomatch | {integer(), integer()}.
suffix_match(_Bin, _Pat, _Size, _Match=0) ->
nomatch;
suffix_match(Bin, Pat, Size, Match) when Match < 0 ->
case binary:match(Bin, Pat, [{scope, {Size, Match}}]) of
{Pos, Len}=Part when Pos + Len =:= Size -> Part;
{_, Len} -> suffix_match(Bin, Pat, Size, Match + Len);
nomatch -> nomatch
end.
%% @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(), patterns()) -> 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(), patterns()) -> 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(), patterns()) -> 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(), patterns()) -> more(part_result()).
parse_headers(Bin, Pattern) ->
parse_headers(Bin, Pattern, []).
-spec parse_headers(binary(), patterns(), http_headers()) -> more(part_result()).
parse_headers(Bin, Pattern, Acc) ->
case erlang:decode_packet(httph_bin, Bin, []) of
{ok, {http_header, _, Name, _, Value}, Rest} ->
Name2 = case is_atom(Name) of
true -> cowboy_bstr:to_lower(atom_to_binary(Name, latin1));
false -> cowboy_bstr:to_lower(Name)
end,
parse_headers(Rest, Pattern, [{Name2, 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(), patterns()) -> 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 ->
case suffix_match(Bin, Pattern) of
nomatch ->
%% Prefix of boundary not found at end of input. it's
%% safe to return the whole binary. Saves copying of
%% next input onto tail of current input binary.
{body, Bin, fun () -> parse_body(<<>>, Pattern) end};
{BoundaryStart, Len} ->
PBody = binary:part(Bin, BoundaryStart, Len),
Rest = binary:part(Bin, 0, BoundaryStart),
{body, PBody, fun () -> parse_body(Rest, Pattern) end}
end
end;
parse_body(Bin, Pattern) ->
more(Bin, fun (NewBin) -> parse_body(NewBin, Pattern) end).
-spec end_of_part(binary(), patterns()) -> end_of_part().
end_of_part(Bin, Pattern) ->
{end_of_part, fun () -> parse_boundary_tail(Bin, Pattern) end}.
-spec skip(binary(), patterns()) -> 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).
suffix_test_() ->
[?_assertEqual(Part, suffix_match(Packet, pattern(Boundary))) ||
{Part, Packet, Boundary} <- [
{nomatch, <<>>, <<"ABC">>},
{{0, 1}, <<"\r">>, <<"ABC">>},
{{0, 2}, <<"\r\n">>, <<"ABC">>},
{{0, 4}, <<"\r\n--">>, <<"ABC">>},
{{0, 5}, <<"\r\n--A">>, <<"ABC">>},
{{0, 6}, <<"\r\n--AB">>, <<"ABC">>},
{{0, 7}, <<"\r\n--ABC">>, <<"ABC">>},
{nomatch, <<"\r\n--AB1">>, <<"ABC">>},
{{1, 1}, <<"1\r">>, <<"ABC">>},
{{2, 2}, <<"12\r\n">>, <<"ABC">>},
{{3, 4}, <<"123\r\n--">>, <<"ABC">>}
]].
-endif.
