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mimemail.erl
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mimemail.erl
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%%% Copyright 2009 Andrew Thompson <andrew@hijacked.us>. All rights reserved.
%%%
%%% Redistribution and use in source and binary forms, with or without
%%% modification, are permitted provided that the following conditions are met:
%%%
%%% 1. Redistributions of source code must retain the above copyright notice,
%%% this list of conditions and the following disclaimer.
%%% 2. Redistributions in binary form must reproduce the above copyright
%%% notice, this list of conditions and the following disclaimer in the
%%% documentation and/or other materials provided with the distribution.
%%%
%%% THIS SOFTWARE IS PROVIDED BY THE FREEBSD PROJECT ``AS IS'' AND ANY EXPRESS OR
%%% IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
%%% MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
%%% EVENT SHALL THE FREEBSD PROJECT OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
%%% INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
%%% (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
%%% LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
%%% ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
%%% (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
%%% SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
%% @doc A module for decoding/encoding MIME 1.0 email.
%% The encoder and decoder operate on the same data structure, which is as follows:
%% A 5-tuple with the following elements: `{Type, SubType, Headers, Parameters, Body}'.
%%
%% `Type' and `SubType' are the MIME type of the email, examples are `text/plain' or
%% `multipart/alternative'. The decoder splits these into 2 fields so you can filter by
%% the main type or by the subtype.
%%
%% `Headers' consists of a list of key/value pairs of binary values eg.
%% `{<<"From">>, <<"Andrew Thompson <andrew@hijacked.us>">>}'. There is no parsing of
%% the header aside from un-wrapping the lines and splitting the header name from the
%% header value.
%%
%% `Parameters' is a list of 3 key/value tuples. The 3 keys are `<<"content-type-params">>',
%% `<<"dispisition">>' and `<<"disposition-params">>'.
%% `content-type-params' is a key/value list of parameters on the content-type header, this
%% usually consists of things like charset and the format parameters. `disposition' indicates
%% how the data wants to be displayed, this is usually 'inline'. `disposition-params' is a list of
%% disposition information, eg. the filename this section should be saved as, the modification
%% date the file should be saved with, etc.
%%
%% Finally, `Body' can be one of several different types, depending on the structure of the email.
%% For a simple email, the body will usually be a binary consisting of the message body, In the
%% case of a multipart email, its a list of these 5-tuple MIME structures. The third possibility,
%% in the case of a message/rfc822 attachment, body can be a single 5-tuple MIME structure.
%%
%% You should see the relevant RFCs (2045, 2046, 2047, etc.) for more information.
%%
%% Note that parts of this module (e.g., `decode/2') use the
%% <a href="https://hex.pm/packages/iconv"><tt>iconv</tt></a> library for string conversion,
%% which you will need to explicitly list as a dependency.
-module(mimemail).
-ifdef(TEST).
-include_lib("eunit/include/eunit.hrl").
-export([rfc2047_utf8_encode/1]).
-endif.
-export([encode/1, encode/2, decode/2, decode/1, get_header_value/2, get_header_value/3, parse_headers/1]).
-export([encode_quoted_printable/1, decode_quoted_printable/1]).
-export_type([
mimetuple/0,
mime_type/0,
mime_subtype/0,
headers/0,
parameters/0,
options/0,
dkim_options/0
]).
-include_lib("kernel/include/logger.hrl").
-define(LOGGER_META, #{domain => [gen_smtp]}).
-define(DEFAULT_MIME_VERSION, <<"1.0">>).
-define(DEFAULT_OPTIONS, [
% default encoding is utf-8 if we can find the iconv module
{encoding, get_default_encoding()},
% should we decode any base64/quoted printable attachments?
{decode_attachments, true},
% should we assume default mime version
{allow_missing_version, true},
% default mime version
{default_mime_version, ?DEFAULT_MIME_VERSION}
]).
% `<<"text">>'
-type mime_type() :: binary().
% `<<"plain">>'
-type mime_subtype() :: binary().
% `[{<<"Content-Type">>, <<"text/plain">>}]'
-type headers() :: [{binary(), binary()}].
-type parameters() ::
%% <<"7bit">> | <<"base64">> | <<"quoted-printable">> etc
#{
transfer_encoding => binary(),
%% [{<<"charset">>, <<"utf-8">>} | {<<"boundary">>, binary()} | {<<"name">>, binary()} etc...]
content_type_params => [{binary(), binary()}],
%% <<"inline">> | <<"attachment">> etc...
disposition => binary(),
%% [{<<"filename">>, binary()}, ]
disposition_params => [{binary(), binary()}]
}.
-type mimetuple() :: {
mime_type(),
mime_subtype(),
headers(),
parameters(),
Body :: binary() | mimetuple() | [mimetuple()]
}.
-type dkim_priv_key() ::
{pem_plain, binary()}
| {pem_encrypted, Key :: binary(), Passwd :: string()}.
-type dkim_options() :: [
{h, [binary()]}
| {d, binary()}
| {s, binary()}
| {t, now | calendar:datetime()}
| {x, calendar:datetime()}
| {c, {simple | relaxed, simple | relaxed}}
| {a, 'rsa-sha256' | 'ed25519-sha256'}
| {private_key, dkim_priv_key()}
].
-type options() :: [
{encoding, binary()}
| {decode_attachment, boolean()}
| {dkim, dkim_options()}
| {allow_missing_version, boolean()}
| {default_mime_version, binary()}
].
-spec decode(Email :: binary()) -> mimetuple().
%% @doc Decode a MIME email from a binary.
decode(All) ->
{Headers, Body} = parse_headers(All),
decode(Headers, Body, ?DEFAULT_OPTIONS).
-spec decode(Email :: binary(), Options :: options()) -> mimetuple().
%% @doc Decode with custom options
decode(All, Options) when is_binary(All), is_list(Options) ->
{Headers, Body} = parse_headers(All),
decode(Headers, Body, Options).
decode(OrigHeaders, Body, Options) ->
?LOG_DEBUG("headers: ~p", [OrigHeaders], ?LOGGER_META),
Encoding = proplists:get_value(encoding, Options, none),
%FixedHeaders = fix_headers(Headers),
Headers = decode_headers(OrigHeaders, [], Encoding),
case parse_with_comments(get_header_value(<<"MIME-Version">>, Headers)) of
undefined ->
AllowMissingVersion = proplists:get_value(allow_missing_version, Options, false),
case parse_content_type(get_header_value(<<"Content-Type">>, Headers)) of
{<<"multipart">>, _SubType, _Parameters} when AllowMissingVersion ->
MimeVersion = proplists:get_value(default_mime_version, Options, ?DEFAULT_MIME_VERSION),
decode_component(Headers, Body, MimeVersion, Options);
{<<"multipart">>, _SubType, _Parameters} ->
erlang:error(non_mime_multipart);
{Type, SubType, CTParameters} ->
NewBody = decode_body(
get_header_value(<<"Content-Transfer-Encoding">>, Headers),
Body,
proplists:get_value(<<"charset">>, CTParameters),
Encoding
),
{Disposition, DispositionParams} =
case parse_content_disposition(get_header_value(<<"Content-Disposition">>, Headers)) of
undefined ->
{<<"inline">>, []};
Disp ->
Disp
end,
Parameters = #{
content_type_params => CTParameters,
disposition => Disposition,
disposition_params => DispositionParams
},
{Type, SubType, Headers, Parameters, NewBody};
undefined ->
Parameters = #{
content_type_params => [{<<"charset">>, <<"us-ascii">>}],
disposition => <<"inline">>,
disposition_params => []
},
{<<"text">>, <<"plain">>, Headers, Parameters,
decode_body(get_header_value(<<"Content-Transfer-Encoding">>, Headers), Body)}
end;
Other ->
decode_component(Headers, Body, Other, Options)
end.
-spec encode(MimeMail :: mimetuple()) -> binary().
encode(MimeMail) ->
encode(MimeMail, []).
%% @doc Encode a MIME tuple to a binary.
encode({Type, Subtype, Headers, ContentTypeParams, Parts}, Options) ->
{FixedParams, FixedHeaders} = ensure_content_headers(Type, Subtype, ContentTypeParams, Headers, Parts, true),
CheckedHeaders = check_headers(FixedHeaders),
EncodedBody = binstr:join(
encode_component(Type, Subtype, CheckedHeaders, FixedParams, Parts),
"\r\n"
),
EncodedHeaders = encode_headers(CheckedHeaders),
SignedHeaders =
case proplists:get_value(dkim, Options) of
undefined -> EncodedHeaders;
DKIM -> dkim_sign_email(EncodedHeaders, EncodedBody, DKIM)
end,
list_to_binary([
binstr:join(SignedHeaders, "\r\n"),
"\r\n\r\n",
EncodedBody
]);
encode(_, _) ->
?LOG_DEBUG("Not a mime-decoded DATA", ?LOGGER_META),
erlang:error(non_mime).
decode_headers(Headers, _, none) ->
Headers;
decode_headers([], Acc, _Charset) ->
lists:reverse(Acc);
decode_headers([{Key, Value} | Headers], Acc, Charset) ->
decode_headers(Headers, [{Key, decode_header(Value, Charset)} | Acc], Charset).
decode_header(Value, Charset) ->
RTokens = tokenize_header(Value, []),
Tokens = lists:reverse(RTokens),
Decoded =
try
decode_header_tokens_strict(Tokens, Charset)
catch
Type:Reason:Stacktrace ->
case decode_header_tokens_permissive(Tokens, Charset, []) of
{ok, Dec} ->
Dec;
error ->
% re-throw original error
erlang:raise(Type, Reason, Stacktrace)
end
end,
iolist_to_binary(Decoded).
-type hdr_token() :: binary() | {Encoding :: binary(), Data :: binary()}.
-spec tokenize_header(binary(), [hdr_token()]) -> [hdr_token()].
tokenize_header(<<>>, Acc) ->
Acc;
tokenize_header(Value, Acc) ->
%% maybe replace "?([^\s]+)\\?" with "?([^\s]*)\\?"?
%% see msg lvuvmm593b8s7pqqfhu7cdtqd4g4najh
%% Subject: =?utf-8?Q??=
%% =?utf-8?Q?=D0=9F=D0=BE=D0=B4=D1=82=D0=B2=D0=B5=D1=80=D0=B4=D0=B8=D1=82=D0=B5=20?=
%% =?utf-8?Q?=D1=80=D0=B5=D0=B3=D0=B8=D1=81=D1=82=D1=80=D0=B0=D1=86=D0=B8=D1=8E=20?=
%% =?utf-8?Q?=D0=B2=20Moy-Rebenok.ru?=
case re:run(Value, "=\\?([-A-Za-z0-9_]+)\\?([qQbB])\\?([^\s]+)\\?=", [ungreedy]) of
nomatch ->
[Value | Acc];
{match, [{AllStart, AllLen}, {EncodingStart, EncodingLen}, {TypeStart, _}, {DataStart, DataLen}]} ->
%% RFC 2047 #2 (encoded-word)
Encoding = binstr:substr(Value, EncodingStart + 1, EncodingLen),
Type = binstr:to_lower(binstr:substr(Value, TypeStart + 1, 1)),
Data = binstr:substr(Value, DataStart + 1, DataLen),
EncodedData =
case Type of
<<"q">> ->
%% RFC 2047 #5. (3)
decode_quoted_printable(binary:replace(Data, <<"_">>, <<"=20">>, [global]));
<<"b">> ->
decode_base64(binary:replace(Data, <<"_">>, <<" ">>, [global]))
end,
Offset =
case
re:run(
binstr:substr(Value, AllStart + AllLen + 1),
"^([\s\t\n\r]+)=\\?[-A-Za-z0-9_]+\\?[^\s]\\?[^\s]+\\?=",
[ungreedy]
)
of
nomatch ->
% no 2047 block immediately following
1;
{match, [{_, _}, {_, WhiteSpaceLen}]} ->
1 + WhiteSpaceLen
end,
NewAcc =
case binstr:substr(Value, 1, AllStart) of
<<>> -> [{fix_encoding(Encoding), EncodedData} | Acc];
Other -> [{fix_encoding(Encoding), EncodedData}, Other | Acc]
end,
tokenize_header(binstr:substr(Value, AllStart + AllLen + Offset), NewAcc)
end.
decode_header_tokens_strict([], _) ->
[];
decode_header_tokens_strict([{Encoding, Data} | Tokens], Charset) ->
{ok, S} = convert(Charset, Encoding, Data),
[S | decode_header_tokens_strict(Tokens, Charset)];
decode_header_tokens_strict([Data | Tokens], Charset) ->
[Data | decode_header_tokens_strict(Tokens, Charset)].
%% this decoder can handle folded not-by-RFC UTF headers, when somebody split
%% multibyte string not by characters, but by bytes. It first join folded
%% string and only then decode it with iconv.
decode_header_tokens_permissive([], _, [Result]) when is_binary(Result) ->
{ok, Result};
decode_header_tokens_permissive([], _, Stack) ->
case lists:all(fun erlang:is_binary/1, Stack) of
true -> {ok, lists:reverse(Stack)};
false -> error
end;
decode_header_tokens_permissive([{Enc, Data} | Tokens], Charset, [{Enc, PrevData} | Stack]) ->
NewData = iolist_to_binary([PrevData, Data]),
{ok, S} = convert(Charset, Enc, NewData),
decode_header_tokens_permissive(Tokens, Charset, [S | Stack]);
decode_header_tokens_permissive([NextToken | _] = Tokens, Charset, [{_, _} | Stack]) when
is_binary(NextToken) orelse is_tuple(NextToken)
->
%% practically very rare case "=?utf-8?Q?BROKEN?=\r\n\t=?windows-1251?Q?maybe-broken?="
%% or "=?utf-8?Q?BROKEN?= raw-ascii-string"
%% drop broken value from stack
decode_header_tokens_permissive(Tokens, Charset, Stack);
decode_header_tokens_permissive([Data | Tokens], Charset, Stack) ->
decode_header_tokens_permissive(Tokens, Charset, [Data | Stack]).
%% x-binaryenc is not a real encoding and is not used for text, so let it pass through
convert(_To, <<"x-binaryenc">>, Data) ->
{ok, Data};
convert(To, From, Data) ->
Result = iconv:convert(From, To, Data),
{ok, Result}.
decode_component(Headers, Body, MimeVsn = <<"1.0", _/binary>>, Options) ->
case parse_content_disposition(get_header_value(<<"Content-Disposition">>, Headers)) of
{Disposition, DispositionParams} ->
ok;
% defaults
_ ->
Disposition = <<"inline">>,
DispositionParams = []
end,
case parse_content_type(get_header_value(<<"Content-Type">>, Headers)) of
{<<"multipart">>, SubType, Parameters} ->
case proplists:get_value(<<"boundary">>, Parameters) of
undefined ->
erlang:error(no_boundary);
Boundary ->
?LOG_DEBUG(
"this is a multipart email of type: ~s and boundary ~s", [SubType, Boundary], ?LOGGER_META
),
Parameters2 = #{
content_type_params => Parameters,
disposition => Disposition,
disposition_params => DispositionParams
},
{<<"multipart">>, SubType, Headers, Parameters2,
split_body_by_boundary(Body, list_to_binary(["--", Boundary]), MimeVsn, Options)}
end;
{<<"message">>, <<"rfc822">>, Parameters} ->
{NewHeaders, NewBody} = parse_headers(Body),
Parameters2 = #{
content_type_params => Parameters,
disposition => Disposition,
disposition_params => DispositionParams
},
{<<"message">>, <<"rfc822">>, Headers, Parameters2, decode(NewHeaders, NewBody, Options)};
{Type, SubType, Parameters} ->
?LOG_DEBUG("body is ~s/~s", [Type, SubType], ?LOGGER_META),
Parameters2 = #{
content_type_params => Parameters,
disposition => Disposition,
disposition_params => DispositionParams
},
{Type, SubType, Headers, Parameters2,
decode_body(
get_header_value(<<"Content-Transfer-Encoding">>, Headers),
Body,
proplists:get_value(<<"charset">>, Parameters),
proplists:get_value(encoding, Options, none)
)};
% defaults
undefined ->
Type = <<"text">>,
SubType = <<"plain">>,
Parameters = #{
content_type_params => [{<<"charset">>, <<"us-ascii">>}],
disposition => Disposition,
disposition_params => DispositionParams
},
{Type, SubType, Headers, Parameters,
decode_body(get_header_value(<<"Content-Transfer-Encoding">>, Headers), Body)}
end;
decode_component(_Headers, _Body, Other, _Options) ->
erlang:error({mime_version, Other}).
-spec get_header_value(Needle :: binary(), Headers :: [{binary(), binary()}], Default :: any()) -> binary() | any().
%% @doc Do a case-insensitive header lookup to return that header's value, or the specified default.
get_header_value(Needle, Headers, Default) ->
?LOG_DEBUG("Headers: ~p", [Headers], ?LOGGER_META),
NeedleLower = binstr:to_lower(Needle),
F =
fun({Header, _Value}) ->
binstr:to_lower(Header) =:= NeedleLower
end,
case lists:search(F, Headers) of
% TODO if there's duplicate headers, should we use the first or the last?
{value, {_Header, Value}} ->
Value;
false ->
Default
end.
-spec get_header_value(Needle :: binary(), Headers :: [{binary(), binary()}]) -> binary() | 'undefined'.
%% @doc Do a case-insensitive header lookup to return the header's value, or `undefined'.
get_header_value(Needle, Headers) ->
get_header_value(Needle, Headers, undefined).
-spec parse_with_comments
(Value :: binary()) -> binary() | no_return();
(Value :: atom()) -> atom().
parse_with_comments(Value) when is_binary(Value) ->
parse_with_comments(Value, [], 0, false);
parse_with_comments(Value) ->
Value.
-spec parse_with_comments(Value :: binary(), Acc :: list(), Depth :: non_neg_integer(), Quotes :: boolean()) ->
binary() | no_return().
parse_with_comments(<<>>, _Acc, _Depth, Quotes) when Quotes ->
erlang:error(unterminated_quotes);
parse_with_comments(<<>>, _Acc, Depth, _Quotes) when Depth > 0 ->
erlang:error(unterminated_comment);
parse_with_comments(<<>>, Acc, _Depth, _Quotes) ->
binstr:strip(list_to_binary(lists:reverse(Acc)));
parse_with_comments(<<$\\, H, Tail/binary>>, Acc, Depth, Quotes) when Depth > 0, H > 32, H < 127 ->
parse_with_comments(Tail, Acc, Depth, Quotes);
parse_with_comments(<<$\\, Tail/binary>>, Acc, Depth, Quotes) when Depth > 0 ->
parse_with_comments(Tail, Acc, Depth, Quotes);
parse_with_comments(<<$\\, H, Tail/binary>>, Acc, Depth, Quotes) when H > 32, H < 127 ->
parse_with_comments(Tail, [H | Acc], Depth, Quotes);
parse_with_comments(<<$\\, Tail/binary>>, Acc, Depth, Quotes) ->
parse_with_comments(Tail, [$\\ | Acc], Depth, Quotes);
parse_with_comments(<<$(, Tail/binary>>, Acc, Depth, Quotes) when not Quotes ->
parse_with_comments(Tail, Acc, Depth + 1, Quotes);
parse_with_comments(<<$), Tail/binary>>, Acc, Depth, Quotes) when Depth > 0, not Quotes ->
parse_with_comments(Tail, Acc, Depth - 1, Quotes);
parse_with_comments(<<_, Tail/binary>>, Acc, Depth, Quotes) when Depth > 0 ->
parse_with_comments(Tail, Acc, Depth, Quotes);
%"
parse_with_comments(<<$", T/binary>>, Acc, Depth, true) ->
parse_with_comments(T, Acc, Depth, false);
%"
parse_with_comments(<<$", T/binary>>, Acc, Depth, false) ->
parse_with_comments(T, Acc, Depth, true);
parse_with_comments(<<H, Tail/binary>>, Acc, Depth, Quotes) ->
parse_with_comments(Tail, [H | Acc], Depth, Quotes).
-spec parse_content_type
(Value :: 'undefined') -> 'undefined';
(Value :: binary()) -> {binary(), binary(), [{binary(), binary()}]}.
parse_content_type(undefined) ->
undefined;
parse_content_type(String) ->
try parse_content_disposition(String) of
{RawType, Parameters} ->
case binstr:strchr(RawType, $/) of
Index when Index < 2 ->
throw(bad_content_type);
Index ->
Type = binstr:substr(RawType, 1, Index - 1),
SubType = binstr:substr(RawType, Index + 1),
{binstr:to_lower(Type), binstr:to_lower(SubType), Parameters}
end
catch
bad_disposition ->
throw(bad_content_type)
end.
-spec parse_content_disposition
(Value :: 'undefined') -> 'undefined';
(String :: binary()) -> {binary(), [{binary(), binary()}]}.
parse_content_disposition(undefined) ->
undefined;
parse_content_disposition(String) ->
[Disposition | Parameters] = binstr:split(parse_with_comments(String), <<";">>),
F =
fun(X) ->
Y = binstr:strip(binstr:strip(X), both, $\t),
case binstr:strchr(Y, $=) of
Index when Index < 2 ->
throw(bad_disposition);
Index ->
Key = binstr:substr(Y, 1, Index - 1),
Value = binstr:substr(Y, Index + 1),
{binstr:to_lower(Key), Value}
end
end,
Params = lists:map(F, Parameters),
{binstr:to_lower(Disposition), Params}.
split_body_by_boundary(Body, Boundary, MimeVsn, Options) ->
% find the indices of the first and last boundary
case {binstr:strpos(Body, Boundary), binstr:strpos(Body, list_to_binary([Boundary, "--"]))} of
{0, _} ->
erlang:error(missing_boundary);
{_, 0} ->
erlang:error(missing_last_boundary);
{Start, End} ->
NewBody = binstr:substr(Body, Start + byte_size(Boundary), End - Start),
% from now on, we can be sure that each boundary is preceded by a CRLF
Parts = split_body_by_boundary_(NewBody, list_to_binary(["\r\n", Boundary]), [], Options),
[
decode_component(Headers, Body2, MimeVsn, Options)
|| {Headers, Body2} <- [V || {_, Body3} = V <- Parts, byte_size(Body3) =/= 0]
]
end.
split_body_by_boundary_(<<>>, _Boundary, Acc, _Options) ->
lists:reverse(Acc);
split_body_by_boundary_(Body, Boundary, Acc, Options) ->
% trim the incomplete first line
TrimmedBody = binstr:substr(Body, binstr:strpos(Body, "\r\n") + 2),
case binstr:strpos(TrimmedBody, Boundary) of
0 ->
lists:reverse([{[], TrimmedBody} | Acc]);
Index ->
{ParsedHdrs, BodyRest} = parse_headers(binstr:substr(TrimmedBody, 1, Index - 1)),
DecodedHdrs = decode_headers(ParsedHdrs, [], proplists:get_value(encoding, Options, none)),
split_body_by_boundary_(
binstr:substr(TrimmedBody, Index + byte_size(Boundary)),
Boundary,
[{DecodedHdrs, BodyRest} | Acc],
Options
)
end.
-spec parse_headers(Body :: binary()) -> {[{binary(), binary()}], binary()}.
%% @doc Parse the headers off of a message and return a list of headers and the trailing body.
parse_headers(Body) ->
case binstr:strpos(Body, "\r\n") of
0 ->
{[], Body};
1 ->
{[], binstr:substr(Body, 3)};
Index ->
parse_headers(binstr:substr(Body, Index + 2), binstr:substr(Body, 1, Index - 1), [])
end.
parse_headers(Body, <<H, Tail/binary>>, []) when H =:= $\s; H =:= $\t ->
% folded headers
{[], list_to_binary([H, Tail, "\r\n", Body])};
parse_headers(Body, <<H, T/binary>>, Headers) when H =:= $\s; H =:= $\t ->
% folded headers
[{FieldName, OldFieldValue} | OtherHeaders] = Headers,
FieldValue = list_to_binary([OldFieldValue, T]),
?LOG_DEBUG("~p = ~p", [FieldName, FieldValue], ?LOGGER_META),
case binstr:strpos(Body, "\r\n") of
0 ->
{lists:reverse([{FieldName, FieldValue} | OtherHeaders]), Body};
1 ->
{lists:reverse([{FieldName, FieldValue} | OtherHeaders]), binstr:substr(Body, 3)};
Index2 ->
parse_headers(binstr:substr(Body, Index2 + 2), binstr:substr(Body, 1, Index2 - 1), [
{FieldName, FieldValue} | OtherHeaders
])
end;
parse_headers(Body, Line, Headers) ->
?LOG_DEBUG("line: ~p", [Line], ?LOGGER_META),
case binstr:strchr(Line, $:) of
0 ->
{lists:reverse(Headers), list_to_binary([Line, "\r\n", Body])};
Index ->
FieldName = binstr:substr(Line, 1, Index - 1),
F = fun(X) -> X > 32 andalso X < 127 end,
case binstr:all(F, FieldName) of
true ->
F2 = fun(X) -> (X > 31 andalso X < 127) orelse X == 9 end,
FValue = binstr:strip(binstr:substr(Line, Index + 1)),
FieldValue =
case binstr:all(F2, FValue) of
true ->
FValue;
_ ->
% I couldn't figure out how to use a pure binary comprehension here :(
list_to_binary([filter_non_ascii(C) || <<C:8>> <= FValue])
end,
case binstr:strpos(Body, "\r\n") of
0 ->
{lists:reverse([{FieldName, FieldValue} | Headers]), Body};
1 ->
{lists:reverse([{FieldName, FieldValue} | Headers]), binstr:substr(Body, 3)};
Index2 ->
parse_headers(binstr:substr(Body, Index2 + 2), binstr:substr(Body, 1, Index2 - 1), [
{FieldName, FieldValue} | Headers
])
end;
false ->
{lists:reverse(Headers), list_to_binary([Line, "\r\n", Body])}
end
end.
filter_non_ascii(C) when (C > 31 andalso C < 127); C == 9 ->
<<C>>;
filter_non_ascii(_C) ->
<<"?">>.
decode_body(Type, Body, _InEncoding, none) ->
decode_body(Type, <<<<X/integer>> || <<X>> <= Body, X < 128>>);
decode_body(Type, Body, undefined, _OutEncoding) ->
decode_body(Type, <<<<X/integer>> || <<X>> <= Body, X < 128>>);
decode_body(Type, Body, <<"x-binaryenc">>, _OutEncoding) ->
% Not IANA and does not represent text, so we pass it through
decode_body(Type, Body);
decode_body(Type, Body, InEncoding, OutEncoding) ->
NewBody = decode_body(Type, Body),
InEncodingFixed = fix_encoding(InEncoding),
{ok, ConvertedBody} = convert(OutEncoding, InEncodingFixed, NewBody),
ConvertedBody.
-spec decode_body(Type :: binary() | 'undefined', Body :: binary()) -> binary().
decode_body(undefined, Body) ->
Body;
decode_body(Type, Body) ->
case binstr:to_lower(Type) of
<<"quoted-printable">> ->
decode_quoted_printable(Body);
<<"base64">> ->
decode_base64(Body);
_Other ->
Body
end.
decode_base64(Body) ->
base64:mime_decode(Body).
decode_quoted_printable(Body) ->
decode_quoted_printable(Body, false, <<>>, <<>>).
%% End of Body
decode_quoted_printable(<<>>, _HasSoftEOL, _WSPs, Acc) ->
Acc;
%% CRLF after Soft Linebreak
decode_quoted_printable(<<$\r, $\n, More/binary>>, true, _WSPs, Acc) ->
decode_quoted_printable(More, false, <<>>, Acc);
%% Space or Tab after Soft Linebreak
decode_quoted_printable(<<C, More/binary>>, true, _WSPs, Acc) when C =:= $\s; C =:= $\t ->
decode_quoted_printable(More, true, <<>>, Acc);
%% Other character after Soft Linebreak
decode_quoted_printable(_Body, true, _WSPs, _Acc) ->
throw(badchar);
%% CRLF
decode_quoted_printable(<<$\r, $\n, More/binary>>, false, _WSPs, Acc) ->
decode_quoted_printable(More, false, <<>>, <<Acc/binary, $\r, $\n>>);
%% Space or Tab
decode_quoted_printable(<<C, More/binary>>, false, WSPs, Acc) when C =:= $\s; C =:= $\t ->
decode_quoted_printable(More, false, <<WSPs/binary, C>>, Acc);
%% Encoded char
decode_quoted_printable(<<$=, C1, C2, More/binary>>, false, WSPs, Acc) when
C1 >= $0 andalso C1 =< $9 orelse C1 >= $A andalso C1 =< $F orelse C1 >= $a andalso C1 =< $f,
C2 >= $0 andalso C2 =< $9 orelse C2 >= $A andalso C2 =< $F orelse C2 >= $a andalso C2 =< $f
->
decode_quoted_printable(More, false, <<>>, <<Acc/binary, WSPs/binary, (unhex(C1)):4, (unhex(C2)):4>>);
%% Soft Linebreak
decode_quoted_printable(<<$=, More/binary>>, false, WSPs, Acc) ->
decode_quoted_printable(More, true, <<>>, <<Acc/binary, WSPs/binary>>);
%% Plain character
decode_quoted_printable(<<C, More/binary>>, false, WSPs, Acc) ->
decode_quoted_printable(More, false, <<>>, <<Acc/binary, WSPs/binary, C>>).
check_headers(Headers) ->
Checked = [<<"MIME-Version">>, <<"Date">>, <<"From">>, <<"Message-ID">>, <<"References">>, <<"Subject">>],
check_headers(Checked, lists:reverse(Headers)).
check_headers([], Headers) ->
lists:reverse(Headers);
check_headers([Header | Tail], Headers) ->
case get_header_value(Header, Headers) of
undefined when Header == <<"MIME-Version">> ->
check_headers(Tail, [{<<"MIME-Version">>, <<"1.0">>} | Headers]);
undefined when Header == <<"Date">> ->
check_headers(Tail, [{<<"Date">>, list_to_binary(smtp_util:rfc5322_timestamp())} | Headers]);
undefined when Header == <<"From">> ->
erlang:error(missing_from);
undefined when Header == <<"Message-ID">> ->
check_headers(Tail, [{<<"Message-ID">>, list_to_binary(smtp_util:generate_message_id())} | Headers]);
undefined when Header == <<"References">> ->
case get_header_value(<<"In-Reply-To">>, Headers) of
undefined ->
% ok, whatever
check_headers(Tail, Headers);
ReplyID ->
check_headers(Tail, [{<<"References">>, ReplyID} | Headers])
end;
References when Header == <<"References">> ->
% check if the in-reply-to header, if present, is in references
case get_header_value(<<"In-Reply-To">>, Headers) of
undefined ->
% ok, whatever
check_headers(Tail, Headers);
ReplyID ->
case binstr:strpos(binstr:to_lower(References), binstr:to_lower(ReplyID)) of
0 ->
% okay, tack on the reply-to to the end of References
check_headers(Tail, [
{<<"References">>, list_to_binary([References, " ", ReplyID])}
| proplists:delete(<<"References">>, Headers)
]);
_Index ->
% nothing to do
check_headers(Tail, Headers)
end
end;
_ ->
check_headers(Tail, Headers)
end.
ensure_content_headers(Type, SubType, Parameters, Headers, Body, Toplevel) ->
CheckHeaders = [<<"Content-Type">>, <<"Content-Disposition">>, <<"Content-Transfer-Encoding">>],
CheckHeadersValues = [{Name, get_header_value(Name, Headers)} || Name <- CheckHeaders],
ensure_content_headers(CheckHeadersValues, Type, SubType, Parameters, lists:reverse(Headers), Body, Toplevel).
ensure_content_headers([], _, _, Parameters, Headers, _, _) ->
{Parameters, lists:reverse(Headers)};
ensure_content_headers(
[{<<"Content-Type">>, undefined} | Tail], Type, SubType, Parameters, Headers, Body, Toplevel
) when
(Type == <<"text">> andalso SubType =/= <<"plain">>) orelse Type =/= <<"text">>
->
%% no content-type header, and its not text/plain
CT = io_lib:format("~s/~s", [Type, SubType]),
CTP =
case Type of
<<"multipart">> ->
Boundary =
case proplists:get_value(<<"boundary">>, maps:get(content_type_params, Parameters, [])) of
undefined ->
list_to_binary(smtp_util:generate_message_boundary());
B ->
B
end,
[
{<<"boundary">>, Boundary}
| proplists:delete(<<"boundary">>, maps:get(content_type_params, Parameters, []))
];
<<"text">> ->
Charset =
case proplists:get_value(<<"charset">>, maps:get(content_type_params, Parameters, [])) of
undefined ->
guess_charset(Body);
C ->
C
end,
[
{<<"charset">>, Charset}
| proplists:delete(<<"charset">>, maps:get(content_type_params, Parameters, []))
];
_ ->
maps:get(content_type_params, Parameters, [])
end,
%%CTP = proplists:get_value(<<"content-type-params">>, Parameters, [guess_charset(Body)]),
CTH = binstr:join([CT | encode_parameters(CTP)], ";"),
NewParameters = Parameters#{content_type_params => CTP},
ensure_content_headers(Tail, Type, SubType, NewParameters, [{<<"Content-Type">>, CTH} | Headers], Body, Toplevel);
ensure_content_headers(
[{<<"Content-Type">>, undefined} | Tail],
<<"text">> = Type,
<<"plain">> = SubType,
Parameters,
Headers,
Body,
Toplevel
) ->
%% no content-type header and its text/plain
Charset =
case proplists:get_value(<<"charset">>, maps:get(content_type_params, Parameters, [])) of
undefined ->
guess_charset(Body);
C ->
binstr:to_lower(C)
end,
case Charset of
<<"us-ascii">> ->
% the default
ensure_content_headers(Tail, Type, SubType, Parameters, Headers, Body, Toplevel);
_ ->
CTP = [
{<<"charset">>, Charset}
| proplists:delete(<<"charset">>, maps:get(content_type_params, Parameters, []))
],
CTH = binstr:join([<<"text/plain">> | encode_parameters(CTP)], ";"),
NewParameters = Parameters#{content_type_params => CTP},
ensure_content_headers(
Tail, Type, SubType, NewParameters, [{<<"Content-Type">>, CTH} | Headers], Body, Toplevel
)
end;
ensure_content_headers(
[{<<"Content-Transfer-Encoding">>, undefined} | Tail], Type, SubType, Parameters, Headers, Body, Toplevel
) when
Type =/= <<"multipart">>
->
Enc =
case maps:get(transfer_encoding, Parameters, undefined) of
undefined ->
guess_best_encoding(Body);
Value ->
Value
end,
case Enc of
<<"7bit">> ->
ensure_content_headers(Tail, Type, SubType, Parameters, Headers, Body, Toplevel);
_ ->
ensure_content_headers(
Tail, Type, SubType, Parameters, [{<<"Content-Transfer-Encoding">>, Enc} | Headers], Body, Toplevel
)
end;
ensure_content_headers(
[{<<"Content-Disposition">>, undefined} | Tail], Type, SubType, Parameters, Headers, Body, false = Toplevel
) ->
CD = maps:get(disposition, Parameters, <<"inline">>),
CDP = maps:get(disposition_params, Parameters, []),
CDH = binstr:join([CD | encode_parameters(CDP)], ";"),
ensure_content_headers(
Tail, Type, SubType, Parameters, [{<<"Content-Disposition">>, CDH} | Headers], Body, Toplevel
);
ensure_content_headers([_ | Tail], Type, SubType, Parameters, Headers, Body, Toplevel) ->
ensure_content_headers(Tail, Type, SubType, Parameters, Headers, Body, Toplevel).
guess_charset(Body) ->
case binstr:all(fun(X) -> X < 128 end, Body) of
true -> <<"us-ascii">>;
false -> <<"utf-8">>
end.
guess_best_encoding(Body) ->
case valid_7bit(Body) of
true ->
<<"7bit">>;
false ->
choose_transformation(Body)
end.
choose_transformation(<<Chunk:200/binary, _, _/binary>>) ->
%% Optimization - only analyze 1st 200 bytes
choose_transformation(Chunk);
choose_transformation(Body) ->
{Readable, Encoded} = partition_count_bytes(
fun(C) ->
C >= 16#20 andalso C =< 16#7E orelse C =:= $\r orelse C =:= $\n
end,
Body
),
%based on the % of printable characters, choose an encoding
if
% same as 100 * Readable / (Readable + Encoded) >= 80, but avoiding division
Readable >= 4 * Encoded ->
%% >80% printable characters
<<"quoted-printable">>;
true ->
%% =<80% printable characters
<<"base64">>
end.
%% https://tools.ietf.org/html/rfc2045#section-2.7:
%% * ASCII codes from 1 to 127
%% * \r and \n are only allowed as `\r\n' pair, but not standalone (bare)
%% * No lines over 998 chars
%%
%% Unfortunately, any string that ends with `\n` matches the regexp, so, we need some pre-checks
valid_7bit(<<"\n">>) ->
false;
valid_7bit(<<"\r">>) ->
false;
valid_7bit(<<>>) ->
true;
valid_7bit(<<_>>) ->
true;
valid_7bit(Body) ->
Size = byte_size(Body),
case binary:at(Body, Size - 1) =:= $\n andalso binary:at(Body, Size - 2) =/= $\r of
true ->
%% last element is \n, but the one before the last is not \r
false;
false ->
%% So: (all except `\r` and `\n` in 1-127 range) OR (`\r\n`)
case re:run(Body, "^([\x01-\x09\x0b-\x0c\x0e-\x7f]|(\r\n))*$", [{capture, none}]) of
match -> not has_lines_over_998(Body);
nomatch -> false
end
end.
%% @doc If `Body' has at least one line (ending with `\r\n') that is longer than 998 chars
has_lines_over_998(Body) ->
Pattern = binary:compile_pattern(<<"\r\n">>),
has_lines_over_998(Body, binary:match(Body, Pattern), 0, Pattern).
has_lines_over_998(Bin, nomatch, Offset, _) ->
%% Last line is over 998?
(byte_size(Bin) - Offset) >= 998;
has_lines_over_998(_Bin, {FoundAt, 2}, Offset, _Patern) when (FoundAt - Offset) >= 998 ->
true;
has_lines_over_998(Bin, {FoundAt, 2}, _, Pattern) ->
NewOffset = FoundAt + 2,
Len = byte_size(Bin) - NewOffset,
has_lines_over_998(
Bin, binary:match(Bin, Pattern, [{scope, {NewOffset, Len}}]), NewOffset, Pattern
).
encode_parameters([[]]) ->
[];
encode_parameters(Parameters) ->
[encode_parameter(Parameter) || Parameter <- Parameters].
encode_parameter({X, Y}) ->
YEnc = rfc2047_utf8_encode(Y, byte_size(X) + 3, <<"\t">>),
case escape_tspecial(YEnc, false, <<>>) of
{true, Special} -> [X, $=, $", Special, $"];
false -> [X, $=, YEnc]
end.
% See also: http://www.ietf.org/rfc/rfc2045.txt section 5.1
escape_tspecial(<<>>, false, _Acc) ->
false;
escape_tspecial(<<>>, IsSpecial, Acc) ->
{IsSpecial, Acc};
escape_tspecial(<<C, Rest/binary>>, _IsSpecial, Acc) when C =:= $" ->
escape_tspecial(Rest, true, <<Acc/binary, $\\, $">>);
escape_tspecial(<<C, Rest/binary>>, _IsSpecial, Acc) when C =:= $\\ ->
escape_tspecial(Rest, true, <<Acc/binary, $\\, $\\>>);
escape_tspecial(<<C, Rest/binary>>, _IsSpecial, Acc) when
C =:= $(;
C =:= $);
C =:= $<;
C =:= $>;
C =:= $@;
C =:= $,;
C =:= $;;
C =:= $:;
C =:= $/;
C =:= $[;
C =:= $];
C =:= $?;
C =:= $=;
C =:= $\s
->
escape_tspecial(Rest, true, <<Acc/binary, C>>);
escape_tspecial(<<C, Rest/binary>>, IsSpecial, Acc) ->
escape_tspecial(Rest, IsSpecial, <<Acc/binary, C>>).
encode_headers([]) ->
[];
encode_headers([{Key, Value} | T] = _Headers) ->
EncodedHeader = maybe_encode_folded_header(Key, list_to_binary([Key, ": ", encode_header_value(Key, Value)])),
[EncodedHeader | encode_headers(T)].
maybe_encode_folded_header(H, Hdr) when
H =:= <<"To">>;
H =:= <<"Cc">>;
H =:= <<"Bcc">>;
H =:= <<"Reply-To">>;
H =:= <<"From">>
->
Hdr;
maybe_encode_folded_header(_H, Hdr) ->
encode_folded_header(Hdr, <<>>).
encode_folded_header(Rest, Acc) ->
case binstr:split(Rest, <<$;>>, 2) of
[_] ->
<<Acc/binary, Rest/binary>>;
[Before, After] ->
NewPart =
case After of
<<$\t, _Rest/binary>> ->
<<Before/binary, ";\r\n">>;
_ ->
<<Before/binary, ";\r\n\t">>
end,
encode_folded_header(After, <<Acc/binary, NewPart/binary>>)
end.
encode_header_value(H, Value) when
H =:= <<"To">>;
H =:= <<"Cc">>;
H =:= <<"Bcc">>;
H =:= <<"Reply-To">>;
H =:= <<"From">>
->
{ok, Addresses} = smtp_util:parse_rfc5322_addresses(Value),
{Names, Emails} = lists:unzip(Addresses),