trunk: util/sasl.lua@e85726d084d6 (annotated)

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util/sasl.lua@e85726d084d6 (annotated)

util/sasl.lua

2009-06-20

author: Tobias Markmann <tm@ayena.de>
date: Sat Jun 20 19:06:04 2009 +0200
changeset 1374: e85726d084d6
parent 1305: 37657578ea85
child 1376: 13587cf24435
permissions: -rw-r--r--

Adding COMPAT comment.

 -- 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 md5 = require "util.hashes".md5;
 local log = require "util.logger".init("sasl");
 local tostring = tostring;
 local st = require "util.stanza";
 local generate_uuid = require "util.uuid".generate;
 local t_insert, t_concat = table.insert, table.concat;
 local to_byte, to_char = string.byte, string.char;
 local s_match = string.match;
 local gmatch = string.gmatch
 local string = string
 local math = require "math"
 local type = type
 local error = error
 local print = print
 module "sasl"
 local function new_plain(realm, password_handler)
 	local object = { mechanism = "PLAIN", realm = realm, password_handler = password_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
 		local password_encoding, correct_password = self.password_handler(authentication, self.realm, "PLAIN")
 		if correct_password == nil then return "failure", "not-authorized"
 		elseif correct_password == false then return "failure", "account-disabled" end
 		local claimed_password = ""
 		if password_encoding == nil then claimed_password = password
 		else claimed_password = password_encoding(password) end
 		self.username = authentication
 		if claimed_password == correct_password then
 			return "success"
 		else
 			return "failure", "not-authorized"
 		end
 	end
 	return object
 end
 -- implementing RFC 2831
 local function new_digest_md5(realm, password_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["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["realm"] then data = data..[[realm="]]..message.realm..[[",]] 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)
 		message = {}
 		for k, v in gmatch(data, [[([%w%-]+)="?([^",]*)"?,?]]) do -- FIXME The hacky regex makes me shudder
 			message[k] = v;
 		end
 		return message;
 	end
 	local object = { mechanism = "DIGEST-MD5", realm = realm, password_handler = password_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
 			-- 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"] = self.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.password_handler(response["username"], response["realm"], "DIGEST-MD5", 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
 	return object;
 end
 local function new_anonymous(realm, password_handler)
 	local object = { mechanism = "ANONYMOUS", realm = realm, password_handler = password_handler}
 		function object.feed(self, message)
 			return "success"
 		end
 	object["username"] = generate_uuid()
 	return object
 end
 function new(mechanism, realm, password_handler)
 	local object
 	if mechanism == "PLAIN" then object = new_plain(realm, password_handler)
 	elseif mechanism == "DIGEST-MD5" then object = new_digest_md5(realm, password_handler)
 	elseif mechanism == "ANONYMOUS" then object = new_anonymous(realm, password_handler)
 	else
 		log("debug", "Unsupported SASL mechanism: "..tostring(mechanism));
 		return nil
 	end
 	return object
 end
 return _M;

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util/sasl.lua@e85726d084d6 (annotated)

util/sasl.lua