prosody
8fbbdb11a520

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Software / code / prosody

Changeset

2193:8fbbdb11a520

Merge with sasl branch.
author Tobias Markmann <tm@ayena.de>
date Mon, 16 Nov 2009 21:43:57 +0100
parents 2080:ca419b92a8c7 (current diff) 2192:fa46d158c95f (diff)
children 2194:41d42d253a1d
files plugins/mod_saslauth.lua util/sasl.lua util/sasl/anonymous.lua util/sasl/digest-md5.lua
diffstat 5 files changed, 442 insertions(+), 266 deletions(-) [+]
line wrap: on
line diff
--- a/plugins/mod_saslauth.lua	Fri Nov 13 06:29:37 2009 +0500
+++ b/plugins/mod_saslauth.lua	Mon Nov 16 21:43:57 2009 +0100
@@ -1,7 +1,7 @@
 -- Prosody IM
 -- Copyright (C) 2008-2009 Matthew Wild
 -- Copyright (C) 2008-2009 Waqas Hussain
--- 
+--
 -- This project is MIT/X11 licensed. Please see the
 -- COPYING file in the source package for more information.
 --
@@ -35,6 +35,27 @@
 
 local new_sasl = require "util.sasl".new;
 
+default_authentication_profile = {
+	plain = function(username, realm)
+			local prepped_username = nodeprep(username);
+			if not prepped_username then
+				log("debug", "NODEprep failed on username: %s", username);
+				return "", nil;
+			end
+			local password = usermanager_get_password(prepped_username, realm);
+			if not password then
+				return "", nil;
+			end
+			return password, true;
+		end
+};
+
+anonymous_authentication_profile = {
+	anonymous = function(username, realm)
+			return true; -- for normal usage you should always return true here
+		end
+}
+
 local function build_reply(status, ret, err_msg)
 	local reply = st.stanza(status, {xmlns = xmlns_sasl});
 	if status == "challenge" then
@@ -57,50 +78,18 @@
 		session.sasl_handler = nil;
 	elseif status == "success" then
 		local username = nodeprep(session.sasl_handler.username);
-		session.sasl_handler = nil;
 		if not username then -- TODO move this to sessionmanager
 			module:log("warn", "SASL succeeded but we didn't get a username!");
 			session.sasl_handler = nil;
 			session:reset_stream();
 			return;
-		end 
-		sm_make_authenticated(session, username);
+		end
+		sm_make_authenticated(session, session.sasl_handler.username);
+		session.sasl_handler = nil;
 		session:reset_stream();
 	end
 end
 
-local function credentials_callback(mechanism, ...)
-	if mechanism == "PLAIN" then
-		local username, hostname, password = ...;
-		username = nodeprep(username);
-		if not username then
-			return false;
-		end
-		local response = usermanager_validate_credentials(hostname, username, password, mechanism);
-		if response == nil then
-			return false;
-		else
-			return response;
-		end
-	elseif mechanism == "DIGEST-MD5" then
-		local function func(x) return x; end
-		local node, domain, realm, decoder = ...;
-		local prepped_node = nodeprep(node);
-		if not prepped_node then
-			return func, nil;
-		end
-		local password = usermanager_get_password(prepped_node, domain);
-		if password then
-			if decoder then
-				node, realm, password = decoder(node), decoder(realm), decoder(password);
-			end
-			return func, md5(node..":"..realm..":"..password);
-		else
-			return func, nil;
-		end
-	end
-end
-
 local function sasl_handler(session, stanza)
 	if stanza.name == "auth" then
 		-- FIXME ignoring duplicates because ejabberd does
@@ -111,8 +100,8 @@
 		elseif stanza.attr.mechanism == "ANONYMOUS" then
 			return session.send(build_reply("failure", "mechanism-too-weak"));
 		end
-		session.sasl_handler = new_sasl(stanza.attr.mechanism, session.host, credentials_callback);
-		if not session.sasl_handler then
+		local valid_mechanism = session.sasl_handler:select(stanza.attr.mechanism);
+		if not valid_mechanism then
 			return session.send(build_reply("failure", "invalid-mechanism"));
 		end
 	elseif not session.sasl_handler then
@@ -128,7 +117,7 @@
 			return;
 		end
 	end
-	local status, ret, err_msg = session.sasl_handler:feed(text);
+	local status, ret, err_msg = session.sasl_handler:process(text);
 	handle_status(session, status);
 	local s = build_reply(status, ret, err_msg);
 	log("debug", "sasl reply: %s", tostring(s));
@@ -148,16 +137,16 @@
 				if secure_auth_only and not session.secure then
 					return;
 				end
+				if config.get(session.host or "*", "core", "anonymous_login") then
+					session.sasl_handler = new_sasl(session.host, anonymous_authentication_profile);
+				else
+					session.sasl_handler = new_sasl(session.host, default_authentication_profile);
+				end
 				features:tag("mechanisms", mechanisms_attr);
 				-- TODO: Provide PLAIN only if TLS is active, this is a SHOULD from the introduction of RFC 4616. This behavior could be overridden via configuration but will issuing a warning or so.
-					if config.get(session.host or "*", "core", "anonymous_login") then
-						features:tag("mechanism"):text("ANONYMOUS"):up();
-					else
-						local mechanisms = usermanager_get_supported_methods(session.host or "*");
-						for k, v in pairs(mechanisms) do
-							features:tag("mechanism"):text(k):up();
-						end
-					end
+				for k, v in pairs(session.sasl_handler:mechanisms()) do
+					features:tag("mechanism"):text(v):up();
+				end
 				features:up();
 			else
 				features:tag("bind", bind_attr):tag("required"):up():up();
--- a/util/sasl.lua	Fri Nov 13 06:29:37 2009 +0500
+++ b/util/sasl.lua	Mon Nov 16 21:43:57 2009 +0100
@@ -16,9 +16,8 @@
 local log = require "util.logger".init("sasl");
 local tostring = tostring;
 local st = require "util.stanza";
-local generate_uuid = require "util.uuid".generate;
+local pairs, ipairs = pairs, ipairs;
 local t_insert, t_concat = table.insert, table.concat;
-local to_byte, to_char = string.byte, string.char;
 local to_unicode = require "util.encodings".idna.to_unicode;
 local s_match = string.match;
 local gmatch = string.gmatch
@@ -27,244 +26,110 @@
 local type = type
 local error = error
 local print = print
+local setmetatable = setmetatable;
+local assert = assert;
+local dofile = dofile;
+local require = require;
 
+require "util.iterators"
+local keys = keys
+
+local array = require "util.array"
 module "sasl"
 
--- Credentials handler:
---   Arguments: ("PLAIN", user, host, password)
---   Returns: true (success) | false (fail) | nil (user unknown)
-local function new_plain(realm, credentials_handler)
-	local object = { mechanism = "PLAIN", realm = realm, credentials_handler = credentials_handler}
-	function object.feed(self, message)
-		if message == "" or message == nil then return "failure", "malformed-request" end
-		local response = message
-		local authorization = s_match(response, "([^%z]+)")
-		local authentication = s_match(response, "%z([^%z]+)%z")
-		local password = s_match(response, "%z[^%z]+%z([^%z]+)")
-
-    if authentication == nil or password == nil then return "failure", "malformed-request" end
-    self.username = authentication
-    local auth_success = self.credentials_handler("PLAIN", self.username, self.realm, password)
+--[[
+Authentication Backend Prototypes:
 
-    if auth_success then
-      return "success"
-    elseif auth_success == nil then
-      return "failure", "account-disabled"
-    else
-      return "failure", "not-authorized"
-    end
-  end
-  return object
-end
+state = false : disabled
+state = true : enabled
+state = nil : non-existant
 
--- credentials_handler:
---   Arguments: (mechanism, node, domain, realm, decoder)
---   Returns: Password encoding, (plaintext) password
--- implementing RFC 2831
-local function new_digest_md5(realm, credentials_handler)
-	--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
+plain:
+	function(username, realm)
+		return password, state;
 	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
+plain-test:
+	function(username, realm, password)
+		return true or false, state;
+	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;
+digest-md5:
+	function(username, domain, realm, encoding) -- domain and realm are usually the same; for some broken
+												-- implementations it's not
+		return digesthash, state;
 	end
 
-	local object = { mechanism = "DIGEST-MD5", realm = realm, credentials_handler = credentials_handler};
-
-	object.nonce = generate_uuid();
-	object.step = 0;
-	object.nonce_count = {};
-
-	function object.feed(self, message)
-		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
+digest-md5-test:
+	function(username, domain, realm, encoding, digesthash)
+		return true or false, state;
+	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 method = {};
+method.__index = method;
+local mechanisms = {};
+local backend_mechanism = {};
 
-			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
+-- register a new SASL mechanims
+local function registerMechanism(name, backends, f)
+	assert(type(name) == "string", "Parameter name MUST be a string.");
+	assert(type(backends) == "string" or type(backends) == "table", "Parameter backends MUST be either a string or a table.");
+	assert(type(f) == "function", "Parameter f MUST be a function.");
+	mechanisms[name] = f
+	for _, backend_name in ipairs(backends) do
+		if backend_mechanism[backend_name] == nil then backend_mechanism[backend_name] = {}; end
+		t_insert(backend_mechanism[backend_name], name);
+	end
+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 or response.authzid == self.username.."@"..self.realm then
-					-- COMPAT
-					log("warn", "Client is violating RFC 3920 (section 6.1, point 7).");
-					A1 = Y..":"..response["nonce"]..":"..response["cnonce"]..":"..response.authzid;
-				else
-					return "failure", "invalid-authzid";
-				end
-			else
-				A1 = Y..":"..response["nonce"]..":"..response["cnonce"];
+-- create a new SASL object which can be used to authenticate clients
+function new(realm, profile)
+	sasl_i = {profile = profile};
+	sasl_i.realm = realm;
+	return setmetatable(sasl_i, method);
+end
+
+-- get a list of possible SASL mechanims to use
+function method:mechanisms()
+	local mechanisms = {}
+	for backend, f in pairs(self.profile) do
+		print(backend)
+		if backend_mechanism[backend] then
+			for _, mechanism in ipairs(backend_mechanism[backend]) do
+				mechanisms[mechanism] = true;
 			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
-	return object;
+	self["possible_mechanisms"] = mechanisms;
+	return array.collect(keys(mechanisms));
 end
 
--- Credentials handler: Can be nil. If specified, should take the mechanism as
--- the only argument, and return true for OK, or false for not-OK (TODO)
-local function new_anonymous(realm, credentials_handler)
-	local object = { mechanism = "ANONYMOUS", realm = realm, credentials_handler = credentials_handler}
-		function object.feed(self, message)
-			return "success"
-		end
-	object["username"] = generate_uuid()
-	return object
+-- select a mechanism to use
+function method:select(mechanism)
+	if self.mech_i then
+		return false;
+	end
+	
+	self.mech_i = mechanisms[mechanism]
+	if self.mech_i == nil then 
+		return false;
+	end
+	return true;
 end
 
+-- feed new messages to process into the library
+function method:process(message)
+	--if message == "" or message == nil then return "failure", "malformed-request" end
+	return self.mech_i(self, message);
+end
 
-function new(mechanism, realm, credentials_handler)
-	local object
-	if mechanism == "PLAIN" then object = new_plain(realm, credentials_handler)
-	elseif mechanism == "DIGEST-MD5" then object = new_digest_md5(realm, credentials_handler)
-	elseif mechanism == "ANONYMOUS" then object = new_anonymous(realm, credentials_handler)
-	else
-		log("debug", "Unsupported SASL mechanism: "..tostring(mechanism));
-		return nil
-	end
-	return object
+-- load the mechanisms
+load_mechs = {"plain", "digest-md5", "anonymous"}
+for _, mech in ipairs(load_mechs) do
+	local name = "util.sasl."..mech;
+	local m = require(name);
+	m.init(registerMechanism)
 end
 
 return _M;
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/util/sasl/anonymous.lua	Mon Nov 16 21:43:57 2009 +0100
@@ -0,0 +1,35 @@
+-- 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.
+
+local s_match = string.match;
+
+local log = require "util.logger".init("sasl");
+
+module "anonymous"
+
+--=========================
+--SASL ANONYMOUS according to RFC 4505
+local function anonymous(self, message)
+	local username;
+	repeat
+		username = generate_uuid();
+	until self.profile.anonymous(username, self.realm);
+	self["username"] = username;
+	return "success"
+end
+
+function init(registerMechanism)
+	registerMechanism("ANONYMOUS", {"anonymous"}, anonymous);
+end
+
+return _M;
\ No newline at end of file
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/util/sasl/digest-md5.lua	Mon Nov 16 21:43:57 2009 +0100
@@ -0,0 +1,232 @@
+-- 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.
+
+local tostring = tostring;
+local type = type;
+
+local s_gmatch = string.gmatch;
+local s_match = string.match;
+local t_concat = table.concat;
+local t_insert = table.insert;
+local to_byte, to_char = string.byte, string.char;
+
+local md5 = require "util.hashes".md5;
+local log = require "util.logger".init("sasl");
+local generate_uuid = require "util.uuid".generate;
+
+module "plain"
+
+--=========================
+--SASL DIGEST-MD5 according to RFC 2831
+local function digest_response()
+	
+	return response, A1, A2
+end
+
+local function digest(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 s_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 s_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 = self.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"];
+		if self.profile.plain then
+			local password, state = self.profile.plain(response["username"], self.realm)
+			if state == nil then return "failure", "not-authorized"
+			elseif state == false then return "failure", "account-disabled" end
+			Y = md5(response["username"]..":"..response["realm"]..":"..password);
+		elseif self.profile["digest-md5"] then
+			local Y, state = self.profile["digest-md5"](response["username"], self.realm, response["realm"], response["charset"])
+			if state == nil then return "failure", "not-authorized"
+			elseif state == false then return "failure", "account-disabled" end
+		elseif self.profile["digest-md5-test"] then
+			-- TODO
+		end
+		--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 or response.authzid == self.username.."@"..self.realm then
+				-- COMPAT
+				log("warn", "Client is violating RFC 3920 (section 6.1, point 7).");
+				A1 = Y..":"..response["nonce"]..":"..response["cnonce"]..":"..response.authzid;
+			else
+				return "failure", "invalid-authzid";
+			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;
+			--TODO: considering sending the rspauth in a success node for saving one roundtrip; allowed according to http://tools.ietf.org/html/draft-saintandre-rfc3920bis-09#section-7.3.6
+			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
+
+function init(registerMechanism)
+	registerMechanism("DIGEST-MD5", {"plain"}, digest);
+end
+
+return _M;
\ No newline at end of file
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/util/sasl/plain.lua	Mon Nov 16 21:43:57 2009 +0100
@@ -0,0 +1,55 @@
+-- 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.
+
+local s_match = string.match;
+
+module "plain"
+
+--=========================
+--SASL PLAIN according to RFC 4616
+local function plain(self, message)
+	local response = message
+	local authorization = s_match(response, "([^%z]+)")
+	local authentication = s_match(response, "%z([^%z]+)%z")
+	local password = s_match(response, "%z[^%z]+%z([^%z]+)")
+
+	if authentication == nil or password == nil then
+		return "failure", "malformed-request";
+	end
+
+	local correct, state = false, false;
+	if self.profile.plain then
+		local correct_password;
+		correct_password, state = self.profile.plain(authentication, self.realm);
+		if correct_password == password then correct = true; else correct = false; end
+	elseif self.profile.plain_test then
+		correct, state = self.profile.plain_test(authentication, self.realm, password);
+	end
+
+	self.username = authentication
+	if not state then
+		return "failure", "account-disabled";
+	end
+
+	if correct then
+		return "success";
+	else
+		return "failure", "not-authorized";
+	end
+end
+
+function init(registerMechanism)
+	registerMechanism("PLAIN", {"plain", "plain_test"}, plain);
+end
+
+return _M;
\ No newline at end of file