%%%----------------------------------------------------------------------
%%% File : xml.erl
%%% Author : Alexey Shchepin <alexey@process-one.net>
%%% Purpose : XML utils
%%% Created : 20 Nov 2002 by Alexey Shchepin <alexey@process-one.net>
%%%
%%%
%%% ejabberd, Copyright (C) 2002-2008 Process-one
%%%
%%% This program is free software; you can redistribute it and/or
%%% modify it under the terms of the GNU General Public License as
%%% published by the Free Software Foundation; either version 2 of the
%%% License, or (at your option) any later version.
%%%
%%% This program is distributed in the hope that it will be useful,
%%% but WITHOUT ANY WARRANTY; without even the implied warranty of
%%% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
%%% General Public License for more details.
%%%
%%% You should have received a copy of the GNU General Public License
%%% along with this program; if not, write to the Free Software
%%% Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
%%% 02111-1307 USA
%%%
%%%----------------------------------------------------------------------
-module(xml).
-author('alexey@process-one.net').
-export([element_to_string/1,
crypt/1, make_text_node/1,
remove_cdata/1,
get_cdata/1, get_tag_cdata/1,
get_attr/2, get_attr_s/2,
get_tag_attr/2, get_tag_attr_s/2,
get_subtag/2, get_subtag_cdata/2,
get_path_s/2,
replace_tag_attr/3]).
%% Select at compile time how to escape characters in binary text
%% nodes.
%% Can be choosen with ./configure --enable-full-xml
-ifdef(FULL_XML_SUPPORT).
-define(ESCAPE_BINARY(CData), make_text_node(CData)).
-else.
-define(ESCAPE_BINARY(CData), crypt(CData)).
-endif.
element_to_string(El) ->
case El of
{xmlelement, Name, Attrs, Els} ->
if
Els /= [] ->
[$<, Name, attrs_to_list(Attrs), $>,
[element_to_string(E) || E <- Els],
$<, $/, Name, $>];
true ->
[$<, Name, attrs_to_list(Attrs), $/, $>]
end;
%% We do not crypt CDATA binary, but we enclose it in XML CDATA
{xmlcdata, CData} when binary(CData) ->
?ESCAPE_BINARY(CData);
%% We crypt list and possibly binaries if full XML usage is
%% disabled unsupported (implies a conversion to list).
{xmlcdata, CData} ->
crypt(CData)
end.
attrs_to_list(Attrs) ->
[attr_to_list(A) || A <- Attrs].
attr_to_list({Name, Value}) ->
[$\s, crypt(Name), $=, $', crypt(Value), $'].
crypt(S) when is_list(S) ->
[case C of
$& -> "&";
$< -> "<";
$> -> ">";
$" -> """;
$' -> "'";
_ -> C
end || C <- S];
crypt(S) when is_binary(S) ->
crypt(binary_to_list(S)).
%% Make a cdata_binary depending on what characters it contains
make_text_node(CData) ->
case cdata_need_escape(CData) of
cdata ->
CDATA1 = <<"<![CDATA[">>,
CDATA2 = <<"]]>">>,
concat_binary([CDATA1, CData, CDATA2]);
none ->
CData;
{cdata, EndTokens} ->
EscapedCData = escape_cdata(CData, EndTokens),
concat_binary(EscapedCData)
end.
%% Returns escape type needed for the text node
%% none, cdata, {cdata, [Positions]}
%% Positions is a list a integer containing positions of CDATA end
%% tokens, so that they can be escaped
cdata_need_escape(CData) ->
cdata_need_escape(CData, 0, false, []).
cdata_need_escape(<<>>, _, false, _) ->
none;
cdata_need_escape(<<>>, _, true, []) ->
cdata;
cdata_need_escape(<<>>, _, true, CDataEndTokens) ->
{cdata, lists:reverse(CDataEndTokens)};
cdata_need_escape(<<$],$],$>,Rest/binary>>, CurrentPosition,
_XMLEscape, CDataEndTokens) ->
NewPosition = CurrentPosition + 3,
cdata_need_escape(Rest, NewPosition, true,
[CurrentPosition+1|CDataEndTokens]);
%% Only <, & need to be escaped in XML text node
%% See reference: http://www.w3.org/TR/xml11/#syntax
cdata_need_escape(<<$<,Rest/binary>>, CurrentPosition,
_XMLEscape, CDataEndTokens) ->
cdata_need_escape(Rest, CurrentPosition+1, true, CDataEndTokens);
cdata_need_escape(<<$&,Rest/binary>>, CurrentPosition,
_XMLEscape, CDataEndTokens) ->
cdata_need_escape(Rest, CurrentPosition+1, true, CDataEndTokens);
cdata_need_escape(<<_:8,Rest/binary>>, CurrentPosition,
XMLEscape, CDataEndTokens) ->
cdata_need_escape(Rest, CurrentPosition+1, XMLEscape,
CDataEndTokens).
%% escape cdata that contain CDATA end tokens
%% EndTokens is a list of position of end tokens (integer)
%% This is supposed to be a very rare case: You need to generate several
%% fields, splitting it in the middle of the end token.
%% See example: http://en.wikipedia.org/wiki/CDATA#Uses_of_CDATA_sections
escape_cdata(CData, EndTokens) ->
escape_cdata(CData, 0, EndTokens, []).
escape_cdata(<<>>, _CurrentPosition, [], Acc) ->
lists:reverse(Acc);
escape_cdata(Rest, CurrentPosition, [], Acc) ->
CDATA1 = <<"<![CDATA[">>,
CDATA2 = <<"]]>">>,
escape_cdata(<<>>, CurrentPosition, [], [CDATA2, Rest, CDATA1|Acc]);
escape_cdata(CData, Index, [Pos|Positions], Acc) ->
CDATA1 = <<"<![CDATA[">>,
CDATA2 = <<"]]>">>,
Split = Pos-Index,
{Part, Rest} = split_binary(CData, Split+1),
%% Note: We build the list in reverse to optimize construction
escape_cdata(Rest, Pos+1, Positions, [CDATA2, Part, CDATA1|Acc]).
remove_cdata_p({xmlelement, _Name, _Attrs, _Els}) -> true;
remove_cdata_p(_) -> false.
remove_cdata(L) -> [E || E <- L, remove_cdata_p(E)].
get_cdata(L) ->
binary_to_list(list_to_binary(get_cdata(L, ""))).
get_cdata([{xmlcdata, CData} | L], S) ->
get_cdata(L, [S, CData]);
get_cdata([_ | L], S) ->
get_cdata(L, S);
get_cdata([], S) ->
S.
get_tag_cdata({xmlelement, _Name, _Attrs, Els}) ->
get_cdata(Els).
get_attr(AttrName, Attrs) ->
case lists:keysearch(AttrName, 1, Attrs) of
{value, {_, Val}} ->
{value, Val};
_ ->
false
end.
get_attr_s(AttrName, Attrs) ->
case lists:keysearch(AttrName, 1, Attrs) of
{value, {_, Val}} ->
Val;
_ ->
""
end.
get_tag_attr(AttrName, {xmlelement, _Name, Attrs, _Els}) ->
get_attr(AttrName, Attrs).
get_tag_attr_s(AttrName, {xmlelement, _Name, Attrs, _Els}) ->
get_attr_s(AttrName, Attrs).
get_subtag({xmlelement, _, _, Els}, Name) ->
get_subtag1(Els, Name).
get_subtag1([El | Els], Name) ->
case El of
{xmlelement, Name, _, _} ->
El;
_ ->
get_subtag1(Els, Name)
end;
get_subtag1([], _) ->
false.
get_subtag_cdata(Tag, Name) ->
case get_subtag(Tag, Name) of
false ->
"";
Subtag ->
get_tag_cdata(Subtag)
end.
get_path_s(El, []) ->
El;
get_path_s(El, [{elem, Name} | Path]) ->
case get_subtag(El, Name) of
false ->
"";
SubEl ->
get_path_s(SubEl, Path)
end;
get_path_s(El, [{attr, Name}]) ->
get_tag_attr_s(Name, El);
get_path_s(El, [cdata]) ->
get_tag_cdata(El).
replace_tag_attr(Attr, Value, {xmlelement, Name, Attrs, Els}) ->
Attrs1 = lists:keydelete(Attr, 1, Attrs),
Attrs2 = [{Attr, Value} | Attrs1],
{xmlelement, Name, Attrs2, Els}.
