%%%----------------------------------------------------------------------
%%% File : xml_stream.erl
%%% Author : Alexey Shchepin <alexey@process-one.net>
%%% Purpose : Parse XML streams
%%% Created : 17 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_stream).
-author('alexey@process-one.net').
-export([new/1,
new/2,
parse/2,
close/1,
parse_element/1]).
-define(XML_START, 0).
-define(XML_END, 1).
-define(XML_CDATA, 2).
-define(XML_ERROR, 3).
-define(PARSE_COMMAND, 0).
-define(PARSE_FINAL_COMMAND, 1).
-record(xml_stream_state, {callback_pid, port, stack, size, maxsize}).
process_data(CallbackPid, Stack, Data) ->
case Data of
{?XML_START, {Name, Attrs}} ->
if
Stack == [] ->
catch gen_fsm:send_event(CallbackPid,
{xmlstreamstart, Name, Attrs});
true ->
ok
end,
[{xmlelement, Name, Attrs, []} | Stack];
{?XML_END, EndName} ->
case Stack of
[{xmlelement, Name, Attrs, Els} | Tail] ->
NewEl = {xmlelement, Name, Attrs, lists:reverse(Els)},
case Tail of
[] ->
catch gen_fsm:send_event(CallbackPid,
{xmlstreamend, EndName}),
Tail;
[_] ->
catch gen_fsm:send_event(CallbackPid,
{xmlstreamelement, NewEl}),
Tail;
[{xmlelement, Name1, Attrs1, Els1} | Tail1] ->
[{xmlelement, Name1, Attrs1, [NewEl | Els1]} |
Tail1]
end
end;
{?XML_CDATA, CData} ->
case Stack of
[El] ->
[El];
%% Merge CDATA nodes if they are contiguous
%% This does not change the semantic: the split in
%% several CDATA nodes depends on the TCP/IP packet
%% fragmentation
[{xmlelement, Name, Attrs,
[{xmlcdata, PreviousCData}|Els]} | Tail] ->
[{xmlelement, Name, Attrs,
[{xmlcdata, concat_binary([PreviousCData, CData])} | Els]} | Tail];
%% No previous CDATA
[{xmlelement, Name, Attrs, Els} | Tail] ->
[{xmlelement, Name, Attrs, [{xmlcdata, CData} | Els]} |
Tail];
[] -> []
end;
{?XML_ERROR, Err} ->
catch gen_fsm:send_event(CallbackPid, {xmlstreamerror, Err})
end.
new(CallbackPid) ->
new(CallbackPid, infinity).
new(CallbackPid, MaxSize) ->
Port = open_port({spawn, expat_erl}, [binary]),
#xml_stream_state{callback_pid = CallbackPid,
port = Port,
stack = [],
size = 0,
maxsize = MaxSize}.
parse(#xml_stream_state{callback_pid = CallbackPid,
port = Port,
stack = Stack,
size = Size,
maxsize = MaxSize} = State, Str) ->
StrSize = if
is_list(Str) -> length(Str);
is_binary(Str) -> size(Str)
end,
Res = port_control(Port, ?PARSE_COMMAND, Str),
{NewStack, NewSize} =
lists:foldl(
fun(Data, {St, Sz}) ->
NewSt = process_data(CallbackPid, St, Data),
case NewSt of
[_] -> {NewSt, 0};
_ -> {NewSt, Sz}
end
end, {Stack, Size + StrSize}, binary_to_term(Res)),
if
NewSize > MaxSize ->
catch gen_fsm:send_event(CallbackPid,
{xmlstreamerror, "XML stanza is too big"});
true ->
ok
end,
State#xml_stream_state{stack = NewStack, size = NewSize}.
close(#xml_stream_state{port = Port}) ->
port_close(Port).
parse_element(Str) ->
Port = open_port({spawn, expat_erl}, [binary]),
Res = port_control(Port, ?PARSE_FINAL_COMMAND, Str),
port_close(Port),
process_element_events(binary_to_term(Res)).
process_element_events(Events) ->
process_element_events(Events, []).
process_element_events([], _Stack) ->
{error, parse_error};
process_element_events([Event | Events], Stack) ->
case Event of
{?XML_START, {Name, Attrs}} ->
process_element_events(
Events, [{xmlelement, Name, Attrs, []} | Stack]);
{?XML_END, _EndName} ->
case Stack of
[{xmlelement, Name, Attrs, Els} | Tail] ->
NewEl = {xmlelement, Name, Attrs, lists:reverse(Els)},
case Tail of
[] ->
if
Events == [] ->
NewEl;
true ->
{error, parse_error}
end;
[{xmlelement, Name1, Attrs1, Els1} | Tail1] ->
process_element_events(
Events,
[{xmlelement, Name1, Attrs1, [NewEl | Els1]} |
Tail1])
end
end;
{?XML_CDATA, CData} ->
case Stack of
[{xmlelement, Name, Attrs, Els} | Tail] ->
process_element_events(
Events,
[{xmlelement, Name, Attrs, [{xmlcdata, CData} | Els]} |
Tail]);
[] ->
process_element_events(Events, [])
end;
{?XML_ERROR, Err} ->
{error, Err}
end.
