Switch to using a more generic credentials_callback/handler for SASL auth.

Not all authentication mechanisms have the same requirements; it makes sense
to provide them only with the information they require (and for them to
depend on that) so that as many auth mechanisms as possible can be supported
with a variety of credentials-storing schemes. This commit patches that together

3 files changed, 80 insertions, 72 deletions

diff --git a/core/usermanager.lua b/core/usermanager.lua
index bd7772ca..c7136e8f 100644
--- a/core/usermanager.lua
+++ b/core/usermanager.lua
@@ -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.
 --
@@ -23,6 +23,7 @@ module "usermanager"
 function validate_credentials(host, username, password, method)
 	log("debug", "User '%s' is being validated", username);
 	local credentials = datamanager.load(username, host, "accounts") or {};
+
 	if method == nil then method = "PLAIN"; end
 	if method == "PLAIN" and credentials.password then -- PLAIN, do directly
 		if password == credentials.password then
@@ -30,7 +31,7 @@ function validate_credentials(host, username, password, method)
 		else
 			return nil, "Auth failed. Invalid username or password.";
 		end
-	end
+  end
 	-- must do md5
 	-- make credentials md5
 	local pwd = credentials.password;
@@ -49,6 +50,10 @@ function validate_credentials(host, username, password, method)
 	end
 end
 
+function get_password(username, host)
+  return (datamanager.load(username, host, "accounts") or {}).password
+end
+
 function user_exists(username, host)
 	return datamanager.load(username, host, "accounts") ~= nil; -- FIXME also check for empty credentials
 end
@@ -58,7 +63,7 @@ function create_user(username, password, host)
 end
 
 function get_supported_methods(host)
-	local methods = {["PLAIN"] = true}; -- TODO this should be taken from the config
+  local methods = {["PLAIN"] = true}; -- TODO this should be taken from the config
 	methods["DIGEST-MD5"] = true;
 	return methods;
 end
diff --git a/plugins/mod_saslauth.lua b/plugins/mod_saslauth.lua
index 56837b99..87f24273 100644
--- a/plugins/mod_saslauth.lua
+++ b/plugins/mod_saslauth.lua
@@ -16,6 +16,8 @@ local base64 = require "util.encodings".base64;
 local datamanager_load = require "util.datamanager".load;
 local usermanager_validate_credentials = require "core.usermanager".validate_credentials;
 local usermanager_get_supported_methods = require "core.usermanager".get_supported_methods;
+local usermanager_user_exists = require "core.usermanager".user_exists;
+local usermanager_get_password = require "core.usermanager".get_password;
 local t_concat, t_insert = table.concat, table.insert;
 local tostring = tostring;
 local jid_split = require "util.jid".split
@@ -65,18 +67,19 @@ local function handle_status(session, status)
 	end
 end
 
-local function password_callback(node, hostname, realm, mechanism, decoder)
-	local password = (datamanager_load(node, hostname, "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
-			if decoder then node, realm, password = decoder(node), decoder(realm), decoder(password); end
-			return func, md5(node..":"..realm..":"..password);
-		end
-	end
-	return func, nil;
+local function credentials_callback(mechanism, ...)
+  if mechanism == "PLAIN" then
+    local username, hostname, password = arg[1], arg[2], arg[3];
+    local response = usermanager_validate_credentials(hostname, username, password, mechanism)
+    if response == nil then return false
+    else return response end
+  elseif mechanism == "DIGEST-MD5" then
+    function func(x) return x; end
+    local node, domain, realm, decoder = arg[1], arg[2], arg[3], arg[4];
+    local password = usermanager_get_password(node, domain)
+    if decoder then node, realm, password = decoder(node), decoder(realm), decoder(password); end
+    return func, md5(node..":"..realm..":"..password);
+  end
 end
 
 local function sasl_handler(session, stanza)
@@ -89,7 +92,7 @@ local function sasl_handler(session, stanza)
 		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, password_callback);
+		session.sasl_handler = new_sasl(stanza.attr.mechanism, session.host, credentials_callback);
 		if not session.sasl_handler then
 			return session.send(build_reply("failure", "invalid-mechanism"));
 		end
diff --git a/util/sasl.lua b/util/sasl.lua
index 0082b9cc..48412ea7 100644
--- a/util/sasl.lua
+++ b/util/sasl.lua
@@ -1,14 +1,14 @@
 -- 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.
 
 
@@ -30,47 +30,45 @@ local print = print
 
 module "sasl"
 
-local function new_plain(realm, password_handler)
-	local object = { mechanism = "PLAIN", realm = realm, password_handler = password_handler}
+-- 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
-		
-		local password_encoding, correct_password = self.password_handler(authentication, self.realm, 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
 
+    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)
+
+    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
 
+-- credentials_handler:
+--   Arguments: (mechanism, node, domain, realm, decoder)
+--   Returns: Password encoding, (plaintext) password
 -- implementing RFC 2831
-local function new_digest_md5(realm, password_handler)
+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["nonce"] then data = data..[[nonce="]]..message.nonce..[[",]] end
 		if message["qop"] then data = data..[[qop="]]..message.qop..[[",]] end
@@ -81,7 +79,7 @@ local function new_digest_md5(realm, password_handler)
 		data = data:gsub(",$", "")
 		return data
 	end
-	
+
 	local function utf8tolatin1ifpossible(passwd)
 		local i = 1;
 		while i <= #passwd do
@@ -137,16 +135,16 @@ local function new_digest_md5(realm, password_handler)
 		return message;
 	end
 
-	local object = { mechanism = "DIGEST-MD5", realm = realm, password_handler = password_handler};
-	
+	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, 
+			local challenge = serialize({	nonce = object.nonce,
 											qop = "auth",
 											charset = "utf-8",
 											algorithm = "md5-sess",
@@ -158,13 +156,13 @@ local function new_digest_md5(realm, password_handler)
 			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";
@@ -172,23 +170,23 @@ local function new_digest_md5(realm, password_handler)
 				-- 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
@@ -197,10 +195,10 @@ local function new_digest_md5(realm, password_handler)
 			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"], to_unicode(domain), response["realm"], "DIGEST-MD5", decoder);
+			local password_encoding, Y = self.credentials_handler("DIGEST-MD5", response["username"], to_unicode(domain), response["realm"], decoder);
 			if Y == nil then return "failure", "not-authorized"
 			elseif Y == false then return "failure", "account-disabled" end
 			local A1 = "";
@@ -216,27 +214,27 @@ local function new_digest_md5(realm, password_handler)
 				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							
+			end
 		elseif self.step == 3 then
 			if self.authenticated ~= nil then return "success"
 			else return "failure", "malformed-request" end
@@ -245,8 +243,10 @@ local function new_digest_md5(realm, password_handler)
 	return object;
 end
 
-local function new_anonymous(realm, password_handler)
-	local object = { mechanism = "ANONYMOUS", realm = realm, password_handler = password_handler}
+-- 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
@@ -255,11 +255,11 @@ local function new_anonymous(realm, password_handler)
 end
 
 
-function new(mechanism, realm, password_handler)
+function new(mechanism, realm, credentials_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)
+	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