Chapril/xmpp.chapril.org-ejabberd
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xmpp.chapril.org-ejabberd/src/cyrsasl_digest.erl
Pablo Polvorin a8ef64ab45 Fix cyrsasl_digest RFC-2831 2.1.2.1 (EJAB-476) 
Fix sasl digest bug when username|password|resource strings had
all characters <= U+00FF and at least one character >= U+0080.

Warnning:
Note that by fixing the bug, we may be broking compatibility with clients
that "implements" it.
See comments on https://support.process-one.net/browse/EJAB-476
2010-12-02 12:56:21 -03:00

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%%%----------------------------------------------------------------------
%%% File : cyrsasl_digest.erl
%%% Author : Alexey Shchepin <alexey@sevcom.net>
%%% Purpose : DIGEST-MD5 SASL mechanism
%%% Created : 11 Mar 2003 by Alexey Shchepin <alexey@sevcom.net>
%%%
%%%
%%% ejabberd, Copyright (C) 2002-2010 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(cyrsasl_digest).
-author('alexey@sevcom.net').
-export([start/1,
stop/0,
mech_new/1,
mech_step/2]).
-include("ejabberd.hrl").
-include("cyrsasl.hrl").
-behaviour(cyrsasl).
%% @type mechstate() = {state, Step, Nonce, Username, AuthzId, GetPassword, CheckPassword, AuthModule, Host}
%% Step = 1 | 3 | 5
%% Nonce = string()
%% Username = string()
%% AuthzId = string()
%% GetPassword = function()
%% AuthModule = atom()
%% Host = string().
-record(state, {step, nonce, username, authzid, get_password, check_password, auth_module,
host}).
%% @spec (Opts) -> true
%% Opts = term()
start(_Opts) ->
cyrsasl:register_mechanism("DIGEST-MD5", ?MODULE, true).
%% @spec () -> ok
stop() ->
ok.
mech_new(#sasl_params{host=Host, get_password=GetPassword,
check_password_digest=CheckPasswordDigest}) ->
{ok, #state{step = 1,
nonce = randoms:get_string(),
host = Host,
get_password = GetPassword,
check_password = CheckPasswordDigest}}.
%% @spec (State, ClientIn) -> Ok | Continue | Error
%% State = mechstate()
%% ClientIn = string()
%% Ok = {ok, Props}
%% Props = [Prop]
%% Prop = {username, Username} | {authzid, AuthzId} | {auth_module, AuthModule}
%% Username = string()
%% AuthzId = string()
%% AuthModule = atom()
%% Continue = {continue, ServerOut, New_State}
%% ServerOut = string()
%% New_State = mechstate()
%% Error = {error, Reason} | {error, Reason, Username}
%% Reason = term()
mech_step(#state{step = 1, nonce = Nonce} = State, _) ->
{continue,
"nonce=\"" ++ Nonce ++
"\",qop=\"auth\",charset=utf-8,algorithm=md5-sess",
State#state{step = 3}};
mech_step(#state{step = 3, nonce = Nonce} = State, ClientIn) ->
case parse(ClientIn) of
bad ->
{error, 'bad-protocol'};
KeyVals ->
DigestURI = proplists:get_value("digest-uri", KeyVals, ""),
UserName = proplists:get_value("username", KeyVals, ""),
case is_digesturi_valid(DigestURI, State#state.host) of
false ->
?DEBUG("User login not authorized because digest-uri "
"seems invalid: ~p", [DigestURI]),
{error, 'not-authorized', UserName};
true ->
AuthzId = proplists:get_value("authzid", KeyVals, ""),
case (State#state.get_password)(UserName) of
{false, _} ->
{error, 'not-authorized', UserName};
{Passwd, AuthModule} ->
case (State#state.check_password)(UserName, "",
proplists:get_value("response", KeyVals, ""),
fun(PW) -> response(KeyVals, UserName, PW, Nonce, AuthzId,
"AUTHENTICATE") end) of
{true, _} ->
RspAuth = response(KeyVals,
UserName, Passwd,
Nonce, AuthzId, ""),
{continue,
"rspauth=" ++ RspAuth,
State#state{step = 5,
auth_module = AuthModule,
username = UserName,
authzid = AuthzId}};
false ->
{error, 'not-authorized', UserName};
{false, _} ->
{error, 'not-authorized', UserName}
end
end
end
end;
mech_step(#state{step = 5,
auth_module = AuthModule,
username = UserName,
authzid = AuthzId}, "") ->
{ok, [{username, UserName}, {authzid, AuthzId},
{auth_module, AuthModule}]};
mech_step(A, B) ->
?DEBUG("SASL DIGEST: A ~p B ~p", [A,B]),
{error, 'bad-protocol'}.
%% @spec (S) -> [{Key, Value}] | bad
%% S = string()
%% Key = string()
%% Value = string()
parse(S) ->
parse1(S, "", []).
%% @hidden
parse1([$= | Cs], S, Ts) ->
parse2(Cs, lists:reverse(S), "", Ts);
parse1([$, | Cs], [], Ts) ->
parse1(Cs, [], Ts);
parse1([$\s | Cs], [], Ts) ->
parse1(Cs, [], Ts);
parse1([C | Cs], S, Ts) ->
parse1(Cs, [C | S], Ts);
parse1([], [], T) ->
lists:reverse(T);
parse1([], _S, _T) ->
bad.
%% @hidden
parse2([$\" | Cs], Key, Val, Ts) ->
parse3(Cs, Key, Val, Ts);
parse2([C | Cs], Key, Val, Ts) ->
parse4(Cs, Key, [C | Val], Ts);
parse2([], _, _, _) ->
bad.
%% @hidden
parse3([$\" | Cs], Key, Val, Ts) ->
parse4(Cs, Key, Val, Ts);
parse3([$\\, C | Cs], Key, Val, Ts) ->
parse3(Cs, Key, [C | Val], Ts);
parse3([C | Cs], Key, Val, Ts) ->
parse3(Cs, Key, [C | Val], Ts);
parse3([], _, _, _) ->
bad.
%% @hidden
parse4([$, | Cs], Key, Val, Ts) ->
parse1(Cs, "", [{Key, lists:reverse(Val)} | Ts]);
parse4([$\s | Cs], Key, Val, Ts) ->
parse4(Cs, Key, Val, Ts);
parse4([C | Cs], Key, Val, Ts) ->
parse4(Cs, Key, [C | Val], Ts);
parse4([], Key, Val, Ts) ->
parse1([], "", [{Key, lists:reverse(Val)} | Ts]).
%% @spec (DigestURICase, JabberHost) -> bool()
%% DigestURICase = string()
%% JabberHost = string()
%%
%% @doc Check if the digest-uri is valid.
%% RFC-2831 allows to provide the IP address in Host,
%% however ejabberd doesn't allow that.
%% If the service (for example jabber.example.org)
%% is provided by several hosts (being one of them server3.example.org),
%% then digest-uri can be like xmpp/server3.example.org/jabber.example.org
%% In that case, ejabberd only checks the service name, not the host.
is_digesturi_valid(DigestURICase, JabberHost) ->
DigestURI = exmpp_stringprep:to_lower(DigestURICase),
case catch string:tokens(DigestURI, "/") of
["xmpp", Host] when Host == JabberHost ->
true;
["xmpp", _Host, ServName] when ServName == JabberHost ->
true;
_ ->
false
end.
%% @hidden
digit_to_xchar(D) when (D >= 0) and (D < 10) ->
D + 48;
digit_to_xchar(D) ->
D + 87.
%% @hidden
hex(S) ->
hex(S, []).
%% @hidden
hex([], Res) ->
lists:reverse(Res);
hex([N | Ns], Res) ->
hex(Ns, [digit_to_xchar(N rem 16),
digit_to_xchar(N div 16) | Res]).
%% @spec (KeyVals, User, Passwd, Nonce, AuthzId, A2Prefix) -> string()
%% KeyVals = [{Key, Value}]
%% Key = string()
%% Value = string()
%% User = string()
%% Passwd = string()
%% Nonce = string()
%% AuthzId = nil() | string()
%% A2Prefix = string()
response(KeyVals, User, Passwd, Nonce, AuthzId, A2Prefix) ->
Realm = proplists:get_value("realm", KeyVals, ""),
CNonce = proplists:get_value("cnonce", KeyVals, ""),
DigestURI = proplists:get_value("digest-uri", KeyVals, ""),
NC = proplists:get_value("nc", KeyVals, ""),
QOP = proplists:get_value("qop", KeyVals, ""),
%% handle non-fully latin-1 strings as specified
%% on RFC 2831 Section 2.1.2.1 (EJAB-476)
SUser = sanitize(User),
SPasswd = sanitize(Passwd),
SRealm = sanitize(Realm),
A1 = case AuthzId of
"" ->
binary_to_list(
crypto:md5(SUser ++ ":" ++ SRealm ++ ":" ++ SPasswd)) ++
":" ++ Nonce ++ ":" ++ CNonce;
_ ->
binary_to_list(
crypto:md5(SUser ++ ":" ++ SRealm ++ ":" ++ SPasswd)) ++
":" ++ Nonce ++ ":" ++ CNonce ++ ":" ++ AuthzId
end,
A2 = case QOP of
"auth" ->
A2Prefix ++ ":" ++ DigestURI;
_ ->
A2Prefix ++ ":" ++ DigestURI ++
":00000000000000000000000000000000"
end,
T = hex(binary_to_list(crypto:md5(A1))) ++ ":" ++ Nonce ++ ":" ++
NC ++ ":" ++ CNonce ++ ":" ++ QOP ++ ":" ++
hex(binary_to_list(crypto:md5(A2))),
hex(binary_to_list(crypto:md5(T))).
sanitize(V) ->
L = from_utf8(V),
case lists:all(fun is_latin1/1, L) of
true -> L;
false -> V
end.
%%%% copied from xmerl_ucs:from_utf8/1 and xmerl_ucs:is_latin1/1 , to not
%%%% require xmerl as a dependency only for this.
from_utf8(Bin) when is_binary(Bin) -> from_utf8(binary_to_list(Bin));
from_utf8(List) ->
case expand_utf8(List) of
{Result,0} -> Result;
{_Res,_NumBadChar} ->
exit({ucs,{bad_utf8_character_code}})
end.
%% expand_utf8([Byte]) -> {[UnicodeChar],NumberOfBadBytes}
%% Expand UTF8 byte sequences to ISO 10646/Unicode
%% charactes. Any illegal bytes are removed and the number of
%% bad bytes are returned.
%%
%% Reference:
%% RFC 3629: "UTF-8, a transformation format of ISO 10646".
expand_utf8(Str) ->
expand_utf8_1(Str, [], 0).
expand_utf8_1([C|Cs], Acc, Bad) when C < 16#80 ->
%% Plain Ascii character.
expand_utf8_1(Cs, [C|Acc], Bad);
expand_utf8_1([C1,C2|Cs], Acc, Bad) when C1 band 16#E0 =:= 16#C0,
C2 band 16#C0 =:= 16#80 ->
case ((C1 band 16#1F) bsl 6) bor (C2 band 16#3F) of
C when 16#80 =< C ->
expand_utf8_1(Cs, [C|Acc], Bad);
_ ->
%% Bad range.
expand_utf8_1(Cs, Acc, Bad+1)
end;
expand_utf8_1([C1,C2,C3|Cs], Acc, Bad) when C1 band 16#F0 =:= 16#E0,
C2 band 16#C0 =:= 16#80,
C3 band 16#C0 =:= 16#80 ->
case ((((C1 band 16#0F) bsl 6) bor (C2 band 16#3F)) bsl 6) bor
(C3 band 16#3F) of
C when 16#800 =< C ->
expand_utf8_1(Cs, [C|Acc], Bad);
_ ->
%% Bad range.
expand_utf8_1(Cs, Acc, Bad+1)
end;
expand_utf8_1([C1,C2,C3,C4|Cs], Acc, Bad) when C1 band 16#F8 =:= 16#F0,
C2 band 16#C0 =:= 16#80,
C3 band 16#C0 =:= 16#80,
C4 band 16#C0 =:= 16#80 ->
case ((((((C1 band 16#0F) bsl 6) bor (C2 band 16#3F)) bsl 6) bor
(C3 band 16#3F)) bsl 6) bor (C4 band 16#3F) of
C when 16#10000 =< C ->
expand_utf8_1(Cs, [C|Acc], Bad);
_ ->
%% Bad range.
expand_utf8_1(Cs, Acc, Bad+1)
end;
expand_utf8_1([_|Cs], Acc, Bad) ->
%% Ignore bad character.
expand_utf8_1(Cs, Acc, Bad+1);
expand_utf8_1([], Acc, Bad) -> {lists:reverse(Acc),Bad}.
%%% Test for legitimate Latin-1 code
is_latin1(Ch) when is_integer(Ch), Ch >= 0, Ch =< 255 -> true;
is_latin1(_) -> false.
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