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-- sasl.lua v0.4
-- Copyright (C) 2008-2009 Tobias Markmann
--
-- All rights reserved.
--
-- Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
--
-- * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
-- * 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.
-- * Neither the name of Tobias Markmann nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
--
-- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT OWNER 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.
--=========================
--SASL DIGEST-MD5 according to RFC 2831
local function sasl_mechanism_digest_md5(self, message)
--TODO complete support for authzid
local function serialize(message)
local data = ""
if type(message) ~= "table" then error("serialize needs an argument of type table.") end
-- testing all possible values
if message["realm"] then data = data..[[realm="]]..message.realm..[[",]] end
if message["nonce"] then data = data..[[nonce="]]..message.nonce..[[",]] end
if message["qop"] then data = data..[[qop="]]..message.qop..[[",]] end
if message["charset"] then data = data..[[charset=]]..message.charset.."," end
if message["algorithm"] then data = data..[[algorithm=]]..message.algorithm.."," end
if message["rspauth"] then data = data..[[rspauth=]]..message.rspauth.."," end
data = data:gsub(",$", "")
return data
end
local function utf8tolatin1ifpossible(passwd)
local i = 1;
while i <= #passwd do
local passwd_i = to_byte(passwd:sub(i, i));
if passwd_i > 0x7F then
if passwd_i < 0xC0 or passwd_i > 0xC3 then
return passwd;
end
i = i + 1;
passwd_i = to_byte(passwd:sub(i, i));
if passwd_i < 0x80 or passwd_i > 0xBF then
return passwd;
end
end
i = i + 1;
end
local p = {};
local j = 0;
i = 1;
while (i <= #passwd) do
local passwd_i = to_byte(passwd:sub(i, i));
if passwd_i > 0x7F then
i = i + 1;
local passwd_i_1 = to_byte(passwd:sub(i, i));
t_insert(p, to_char(passwd_i%4*64 + passwd_i_1%64)); -- I'm so clever
else
t_insert(p, to_char(passwd_i));
end
i = i + 1;
end
return t_concat(p);
end
local function latin1toutf8(str)
local p = {};
for ch in gmatch(str, ".") do
ch = to_byte(ch);
if (ch < 0x80) then
t_insert(p, to_char(ch));
elseif (ch < 0xC0) then
t_insert(p, to_char(0xC2, ch));
else
t_insert(p, to_char(0xC3, ch - 64));
end
end
return t_concat(p);
end
local function parse(data)
local message = {}
for k, v in gmatch(data, [[([%w%-]+)="?([^",]*)"?,?]]) do -- FIXME The hacky regex makes me shudder
message[k] = v;
end
return message;
end
if not self.nonce then
self.nonce = generate_uuid();
self.step = 0;
self.nonce_count = {};
end
self.step = self.step + 1;
if (self.step == 1) then
local challenge = serialize({ nonce = object.nonce,
qop = "auth",
charset = "utf-8",
algorithm = "md5-sess",
realm = self.realm});
return "challenge", challenge;
elseif (self.step == 2) then
local response = parse(message);
-- check for replay attack
if response["nc"] then
if self.nonce_count[response["nc"]] then return "failure", "not-authorized" end
end
-- check for username, it's REQUIRED by RFC 2831
if not response["username"] then
return "failure", "malformed-request";
end
self["username"] = response["username"];
-- check for nonce, ...
if not response["nonce"] then
return "failure", "malformed-request";
else
-- check if it's the right nonce
if response["nonce"] ~= tostring(self.nonce) then return "failure", "malformed-request" end
end
if not response["cnonce"] then return "failure", "malformed-request", "Missing entry for cnonce in SASL message." end
if not response["qop"] then response["qop"] = "auth" end
if response["realm"] == nil or response["realm"] == "" then
response["realm"] = "";
elseif response["realm"] ~= self.realm then
return "failure", "not-authorized", "Incorrect realm value";
end
local decoder;
if response["charset"] == nil then
decoder = utf8tolatin1ifpossible;
elseif response["charset"] ~= "utf-8" then
return "failure", "incorrect-encoding", "The client's response uses "..response["charset"].." for encoding with isn't supported by sasl.lua. Supported encodings are latin or utf-8.";
end
local domain = "";
local protocol = "";
if response["digest-uri"] then
protocol, domain = response["digest-uri"]:match("(%w+)/(.*)$");
if protocol == nil or domain == nil then return "failure", "malformed-request" end
else
return "failure", "malformed-request", "Missing entry for digest-uri in SASL message."
end
--TODO maybe realm support
self.username = response["username"];
local password_encoding, Y = self.credentials_handler("DIGEST-MD5", response["username"], self.realm, response["realm"], decoder);
if Y == nil then return "failure", "not-authorized"
elseif Y == false then return "failure", "account-disabled" end
local A1 = "";
if response.authzid then
if response.authzid == self.username.."@"..self.realm then
-- COMPAT
log("warn", "Client is violating XMPP RFC. See section 6.1 of RFC 3920.");
A1 = Y..":"..response["nonce"]..":"..response["cnonce"]..":"..response.authzid;
else
A1 = "?";
end
else
A1 = Y..":"..response["nonce"]..":"..response["cnonce"];
end
local A2 = "AUTHENTICATE:"..protocol.."/"..domain;
local HA1 = md5(A1, true);
local HA2 = md5(A2, true);
local KD = HA1..":"..response["nonce"]..":"..response["nc"]..":"..response["cnonce"]..":"..response["qop"]..":"..HA2;
local response_value = md5(KD, true);
if response_value == response["response"] then
-- calculate rspauth
A2 = ":"..protocol.."/"..domain;
HA1 = md5(A1, true);
HA2 = md5(A2, true);
KD = HA1..":"..response["nonce"]..":"..response["nc"]..":"..response["cnonce"]..":"..response["qop"]..":"..HA2
local rspauth = md5(KD, true);
self.authenticated = true;
return "challenge", serialize({rspauth = rspauth});
else
return "failure", "not-authorized", "The response provided by the client doesn't match the one we calculated."
end
elseif self.step == 3 then
if self.authenticated ~= nil then return "success"
else return "failure", "malformed-request" end
end
end
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