%%%---------------------------------------------------------------------- %%% File : xml.erl %%% Author : Alexey Shchepin %%% Purpose : XML utils %%% Created : 20 Nov 2002 by Alexey Shchepin %%% %%% %%% ejabberd, Copyright (C) 2002-2009 ProcessOne %%% %%% 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), $/, $>] end; %% We do not crypt CDATA binary, but we enclose it in XML CDATA {xmlcdata, CData} when is_binary(CData) -> ?ESCAPE_BINARY(CData); %% We crypt list and possibly binaries if full XML usage is %% disabled unsupported (implies a conversion to list). {xmlcdata, CData} -> crypt(CData) end. attrs_to_list(Attrs) -> [attr_to_list(A) || A <- Attrs]. attr_to_list({Name, Value}) -> [$\s, crypt(Name), $=, $', crypt(Value), $']. crypt(S) when is_list(S) -> [case C of $& -> "&"; $< -> "<"; $> -> ">"; $" -> """; $' -> "'"; _ -> C end || C <- S]; crypt(S) when is_binary(S) -> crypt(binary_to_list(S)). %% Make a cdata_binary depending on what characters it contains make_text_node(CData) -> case cdata_need_escape(CData) of cdata -> CDATA1 = <<">, CDATA2 = <<"]]>">>, concat_binary([CDATA1, CData, CDATA2]); none -> CData; {cdata, EndTokens} -> EscapedCData = escape_cdata(CData, EndTokens), concat_binary(EscapedCData) end. %% Returns escape type needed for the text node %% none, cdata, {cdata, [Positions]} %% Positions is a list a integer containing positions of CDATA end %% tokens, so that they can be escaped cdata_need_escape(CData) -> cdata_need_escape(CData, 0, false, []). cdata_need_escape(<<>>, _, false, _) -> none; cdata_need_escape(<<>>, _, true, []) -> cdata; cdata_need_escape(<<>>, _, true, CDataEndTokens) -> {cdata, lists:reverse(CDataEndTokens)}; cdata_need_escape(<<$],$],$>,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 = <<">, CDATA2 = <<"]]>">>, escape_cdata(<<>>, CurrentPosition, [], [CDATA2, Rest, CDATA1|Acc]); escape_cdata(CData, Index, [Pos|Positions], Acc) -> CDATA1 = <<">, 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}.