Merge new SASL code from Tobias and Waqas

2 files changed, 233 insertions, 48 deletions

diff --git a/plugins/mod_saslauth.lua b/plugins/mod_saslauth.lua
index 24c82a1c..2a1485d0 100644
--- a/plugins/mod_saslauth.lua
+++ b/plugins/mod_saslauth.lua
@@ -2,10 +2,12 @@
 local st = require "util.stanza";
 local send = require "core.sessionmanager".send_to_session;
 local sm_bind_resource = require "core.sessionmanager".bind_resource;
+local jid
 
 local usermanager_validate_credentials = require "core.usermanager".validate_credentials;
 local t_concat, t_insert = table.concat, table.insert;
 local tostring = tostring;
+local jid_split = require "util.jid".split
 
 local log = require "util.logger".init("mod_saslauth");
 
@@ -15,50 +17,91 @@ local xmlns_stanzas ='urn:ietf:params:xml:ns:xmpp-stanzas';
 
 local new_sasl = require "util.sasl".new;
 
+local function build_reply(status, ret)
+	local reply = st.stanza(status, {xmlns = xmlns_sasl});
+	if status == "challenge" then
+		reply:text(ret or "");
+	elseif status == "failure" then
+		reply:tag(ret):up();
+	elseif status == "success" then
+		reply:text(ret or "");
+	else
+		error("Unknown sasl status: "..status);
+	end
+	return reply;
+end
+
+local function handle_status(session, status)
+	if status == "failure" then
+		session.sasl_handler = nil;
+	elseif status == "success" then
+		if not session.sasl_handler.username then error("SASL succeeded but we didn't get a username!"); end -- TODO move this to sessionmanager
+		sessionmanager.make_authenticated(session, session.sasl_handler.username);
+		session.sasl_handler = nil;
+		session:reset_stream();
+	end
+end
+
+local function password_callback(jid, mechanism)
+	local node, host = jid_split(jid);
+	local password = (datamanager.load(node, host, "accounts") or {}).password; -- FIXME handle hashed passwords
+	local func = function(x) return x; end;
+	if password then
+		if mechanism == "PLAIN" then
+			return func, password;
+		elseif mechanism == "DIGEST-MD5" then
+			return func, require "hashes".md5(node.."::"..password);
+		end
+	end
+	return func, nil;
+end
+
+function do_sasl(session, stanza)
+	local text = stanza[1];
+	if text then
+		text = base64.decode(text);
+		if not text then
+			session.sasl_handler = nil;
+			session.send(build_reply("failure", "incorrect-encoding"));
+			return;
+		end
+	end
+	local status, ret = session.sasl_handler:feed(text);
+	handle_status(session, status);
+	local s = build_reply(status, ret); 
+	log("debug", "sasl reply: "..tostring(s));
+	session.send(s);
+end
+
 add_handler("c2s_unauthed", "auth", xmlns_sasl,
 		function (session, stanza)
 			if not session.sasl_handler then
-				session.sasl_handler = new_sasl(stanza.attr.mechanism, 
-					function (username, password)
-						-- onAuth
-						require "core.usermanager"
-						if usermanager_validate_credentials(session.host, username, password) then
-							return true;
-						end
-						return false;
-					end,
-					function (username)
-						-- onSuccess
-						local success, err = sessionmanager.make_authenticated(session, username);
-						if not success then
-							sessionmanager.destroy_session(session);
-							return;
-						end
-						session.sasl_handler = nil;
-						session:reset_stream();
-					end,
-					function (reason)
-						-- onFail
-						log("debug", "SASL failure, reason: %s", reason);
-					end,
-					function (stanza)
-						-- onWrite
-						log("debug", "SASL writes: %s", tostring(stanza));
-						send(session, stanza);
-					end
-				);
-				session.sasl_handler:feed(stanza);	
+				session.sasl_handler = new_sasl(stanza.attr.mechanism, session.host, password_callback);
+				do_sasl(session, stanza);
 			else
 				error("Client tried to negotiate SASL again", 0);
 			end
-			
 		end);
-		
+
+add_handler("c2s_unauthed", "abort", xmlns_sasl,
+	function(session, stanza)
+		if not session.sasl_handler then error("Attempt to abort when sasl has not started"); end
+		do_sasl(session, stanza);
+	end);
+
+add_handler("c2s_unauthed", "response", xmlns_sasl,
+	function(session, stanza)
+		if not session.sasl_handler then error("Attempt to respond when sasl has not started"); end
+		do_sasl(session, stanza);
+	end);
+
 add_event_hook("stream-features", 
 					function (session, features)												
 						if not session.username then
 							t_insert(features, "<mechanisms xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>");
+							-- 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.
 								t_insert(features, "<mechanism>PLAIN</mechanism>");
+								t_insert(features, "<mechanism>DIGEST-MD5</mechanism>");
 							t_insert(features, "</mechanisms>");
 						else
 							t_insert(features, "<bind xmlns='urn:ietf:params:xml:ns:xmpp-bind'><required/></bind>");
diff --git a/util/sasl.lua b/util/sasl.lua
index dbd6326a..430bfe5c 100644
--- a/util/sasl.lua
+++ b/util/sasl.lua
@@ -1,41 +1,183 @@
 
 local base64 = require "base64"
+local md5 = require "md5"
+local crypto = require "crypto"
 local log = require "util.logger".init("sasl");
 local tostring = tostring;
 local st = require "util.stanza";
+local generate_uuid = require "util.uuid".generate;
 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}
+	object.feed = 	function(self, message)
+						--print(message:gsub("%W", function (c) return string.format("\\%d", string.byte(c)) end));
 
-local function new_plain(onAuth, onSuccess, onFail, onWrite)
-	local object = { mechanism = "PLAIN", onAuth = onAuth, onSuccess = onSuccess, onFail = onFail,
-	 				onWrite = onWrite}
-	--local challenge = base64.encode("");
-	--onWrite(st.stanza("challenge", {xmlns = "urn:ietf:params:xml:ns:xmpp-sasl"}):text(challenge))
-	object.feed = 	function(self, stanza)
-						if stanza.name ~= "response" and stanza.name ~= "auth" then self.onFail("invalid-stanza-tag") end
-						if stanza.attr.xmlns ~= "urn:ietf:params:xml:ns:xmpp-sasl" then self.onFail("invalid-stanza-namespace") end
-						local response = base64.decode(stanza[1])
+						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 self.onAuth(authentication, password) == true then
-							self.onWrite(st.stanza("success", {xmlns = "urn:ietf:params:xml:ns:xmpp-sasl"}))
-							self.onSuccess(authentication)
+						
+						local password_encoding, correct_password = self.password_handler(authentication.."@"..self.realm, "PLAIN")
+						
+						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
+							log("debug", "success")
+							return "success", nil
 						else
-							self.onWrite(st.stanza("failure", {xmlns = "urn:ietf:params:xml:ns:xmpp-sasl"}):tag("temporary-auth-failure"));
+							log("debug", "failure")
+							return "failure", "not-authorized"
 						end
 					end
 	return object
 end
 
+local function new_digest_md5(onAuth, onSuccess, onFail, onWrite)
+	--TODO maybe 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 parse(data)
+		message = {}
+		log("debug", "parse-message: "..data)
+		for k, v in gmatch(data, [[([%w%-]+)="?([%w%-%/%.%+=]+)"?,?]]) do
+			message[k] = v
+		log("debug", "               "..k.." = "..v)
+		end
+		return message
+	end
+
+	local object = { mechanism = "DIGEST-MD5", onAuth = onAuth, onSuccess = onSuccess, onFail = onFail,
+	 				onWrite = onWrite }
+	
+	--TODO: something better than math.random would be nice, maybe OpenSSL's random number generator
+	object.nonce = generate_uuid()
+	log("debug", "SASL nonce: "..object.nonce)
+	object.step = 1
+	object.nonce_count = {}
+	local challenge = base64.encode(serialize({	nonce = object.nonce, 
+												qop = "auth",
+												charset = "utf-8",
+												algorithm = "md5-sess"} ));
+	object.onWrite(st.stanza("challenge", {xmlns = "urn:ietf:params:xml:ns:xmpp-sasl"}):text(challenge))
+	object.feed = 	function(self, stanza)
+						log("debug", "SASL step: "..self.step)
+						if stanza.name ~= "response" and stanza.name ~= "auth" then self.onFail("invalid-stanza-tag") end
+						if stanza.attr.xmlns ~= "urn:ietf:params:xml:ns:xmpp-sasl" then self.onFail("invalid-stanza-namespace") end
+						if stanza.name == "auth" then return end
+						self.step = self.step + 1
+						if (self.step == 2) then
+							local response = parse(base64.decode(stanza[1]))
+							-- check for replay attack
+							if response["nc"] then
+								if self.nonce_count[response["nc"]] then self.onFail("not-authorized") end
+							end
+							
+							-- check for username, it's REQUIRED by RFC 2831
+							if not response["username"] then
+								self.onFail("malformed-request")
+							end
+							self["username"] = response["username"] 
+							
+							-- check for nonce, ...
+							if not response["nonce"] then
+								self.onFail("malformed-request")
+							else
+								-- check if it's the right nonce
+								if response["nonce"] ~= tostring(self.nonce) then self.onFail("malformed-request") end
+							end
+							
+							if not response["cnonce"] then self.onFail("malformed-request") end
+							if not response["qop"] then response["qop"] = "auth" end
+							
+							if response["realm"] == nil then response["realm"] = "" end
+							
+							local domain = ""
+							local protocol = ""
+							if response["digest-uri"] then
+								protocol, domain = response["digest-uri"]:match("(%w+)/(.*)$")
+							else
+								error("No digest-uri")
+							end
+														
+							-- compare response_value with own calculation
+							--local A1 = usermanager.get_md5(response["username"], hostname)..":"..response["nonce"]..response["cnonce"]
+							
+							--FIXME actual username and password here :P
+							local X = "tobias:"..response["realm"]..":tobias"
+							local Y = md5.sum(X)
+							local A1 = Y..":"..response["nonce"]..":"..response["cnonce"]--:authzid
+							local A2 = "AUTHENTICATE:"..protocol.."/"..domain
+							
+							local HA1 = md5.sumhexa(A1)
+							local HA2 = md5.sumhexa(A2)
+							
+							local KD = HA1..":"..response["nonce"]..":"..response["nc"]..":"..response["cnonce"]..":"..response["qop"]..":"..HA2
+							local response_value = md5.sumhexa(KD)
+							
+							log("debug", "response_value: "..response_value);
+							log("debug", "response:       "..response["response"]);
+							if response_value == response["response"] then
+								-- calculate rspauth
+								A2 = ":"..protocol.."/"..domain
+								
+								HA1 = md5.sumhexa(A1)
+								HA2 = md5.sumhexa(A2)
+
+								KD = HA1..":"..response["nonce"]..":"..response["nc"]..":"..response["cnonce"]..":"..response["qop"]..":"..HA2
+								local rspauth = md5.sumhexa(KD)
+								
+								self.onWrite(st.stanza("challenge", {xmlns = "urn:ietf:params:xml:ns:xmpp-sasl"}):text(base64.encode(serialize({rspauth = rspauth}))))
+							else
+								self.onWrite(st.stanza("response", {xmlns = "urn:ietf:params:xml:ns:xmpp-sasl"}))
+								self.onFail()
+							end							
+						elseif self.step == 3 then
+							if stanza.name == "response" then 
+								self.onWrite(st.stanza("success", {xmlns = "urn:ietf:params:xml:ns:xmpp-sasl"}))
+								self.onSuccess(self.username)
+							else 
+								self.onFail("Third step isn't a response stanza.")
+							end
+						end
+					end
+	return object
+end
 
-function new(mechanism, onAuth, onSuccess, onFail, onWrite)
+function new(mechanism, realm, password)
 	local object
-	if mechanism == "PLAIN" then object = new_plain(onAuth, onSuccess, onFail, onWrite)
+	if mechanism == "PLAIN" then object = new_plain(realm, password)
+	--elseif mechanism == "DIGEST-MD5" then object = new_digest_md5(ream, password)
 	else
 		log("debug", "Unsupported SASL mechanism: "..tostring(mechanism));
-		onFail("unsupported-mechanism")
+		return nil
 	end
 	return object
 end