-- phpbb3 authentication backend for Prosody

--

-- Copyright (C) 2011 Waqas Hussain

--

local log = require "util.logger".init("auth_sql");

local new_sasl = require "util.sasl".new;

local nodeprep = require "util.encodings".stringprep.nodeprep;

local saslprep = require "util.encodings".stringprep.saslprep;

local DBI = require "DBI"

local md5 = require "util.hashes".md5;

local uuid_gen = require "util.uuid".generate;

local have_bcrypt, bcrypt = pcall(require, "bcrypt"); -- available from luarocks

local connection;

local params = module:get_option("sql");

local resolve_relative_path = require "core.configmanager".resolve_relative_path;

local function test_connection()

	if not connection then return nil; end

	if connection:ping() then

		return true;

	else

		module:log("debug", "Database connection closed");

		connection = nil;

	end

end

local function connect()

	if not test_connection() then

		prosody.unlock_globals();

		local dbh, err = DBI.Connect(

			params.driver, params.database,

			params.username, params.password,

			params.host, params.port

		);

		prosody.lock_globals();

		if not dbh then

			module:log("debug", "Database connection failed: %s", tostring(err));

			return nil, err;

		end

		module:log("debug", "Successfully connected to database");

		dbh:autocommit(true); -- don't run in transaction

		connection = dbh;

		return connection;

	end

end

do -- process options to get a db connection

	params = params or { driver = "SQLite3" };

	if params.driver == "SQLite3" then

		params.database = resolve_relative_path(prosody.paths.data or ".", params.database or "prosody.sqlite");

	end

	assert(params.driver and params.database, "Both the SQL driver and the database need to be specified");

	assert(connect());

end

local function getsql(sql, ...)

	if params.driver == "PostgreSQL" then

		sql = sql:gsub("`", "\"");

	end

	if not test_connection() then connect(); end

	-- do prepared statement stuff

	local stmt, err = connection:prepare(sql);

	if not stmt and not test_connection() then error("connection failed"); end

	if not stmt then module:log("error", "QUERY FAILED: %s %s", err, debug.traceback()); return nil, err; end

	-- run query

	local ok, err = stmt:execute(...);

	if not ok and not test_connection() then error("connection failed"); end

	if not ok then return nil, err; end

	return stmt;

end

local function setsql(sql, ...)

	local stmt, err = getsql(sql, ...);

	if not stmt then return stmt, err; end

	return stmt:affected();

end

local function get_password(username)

	local stmt, err = getsql("SELECT `user_password` FROM `phpbb_users` WHERE `username_clean`=?", username);

	if stmt then

		for row in stmt:rows(true) do

			return row.user_password;

		end

	end

end

local function check_sessionids(username, session_id)

	-- TODO add session expiration and auto-login check

	local stmt, err = getsql("SELECT phpbb_sessions.session_id FROM phpbb_sessions INNER JOIN phpbb_users ON phpbb_users.user_id = phpbb_sessions.session_user_id WHERE phpbb_users.username_clean =?", username);

	if stmt then

		for row in stmt:rows(true) do

			-- if row.session_id == session_id then return true; end

			-- workaround for possible LuaDBI bug

			-- The session_id returned by the sql statement has an additional zero at the end. But that is not in the database.

			if row.session_id == session_id or row.session_id == session_id.."0" then return true; end

		end

	end

end

local itoa64 = "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

local function hashEncode64(input, count)

	local output = "";

	local i, value = 0, 0;

	while true do

		value = input:byte(i+1)

		i = i+1;

		local idx = value % 0x40 + 1;

		output = output .. itoa64:sub(idx, idx);

		if i < count then

			value = value + input:byte(i+1) * 256;

		end

		local _ = value % (2^6);

		local idx = ((value - _) / (2^6)) % 0x40 + 1

		output = output .. itoa64:sub(idx, idx);

		if i >= count then break; end

		i = i+1;

		if i < count then

			value = value + input:byte(i+1) * 256 * 256;

		end

		local _ = value % (2^12);

		local idx = ((value - _) / (2^12)) % 0x40 + 1

		output = output .. itoa64:sub(idx, idx);

		if i >= count then break; end

		i = i+1;

		local _ = value % (2^18);

		local idx = ((value - _) / (2^18)) % 0x40 + 1

		output = output .. itoa64:sub(idx, idx);

		if not(i < count) then break; end

	end

	return output;

end

local function hashCryptPrivate(password, genSalt)

	local output = "*";

	if not genSalt:match("^%$H%$") then return output; end

	local count_log2 = itoa64:find(genSalt:sub(4,4)) - 1;

	if count_log2 < 7 or count_log2 > 30 then return output; end

	local count = 2 ^ count_log2;

	local salt = genSalt:sub(5, 12);

	if #salt ~= 8 then return output; end

	local hash = md5(salt..password);

	while true do

		hash = md5(hash..password);

		if not(count > 1) then break; end

		count = count-1;

	end

	output = genSalt:sub(1, 12);

	output = output .. hashEncode64(hash, 16);

	return output;

end

local function hashGensaltPrivate(input)

	local iteration_count_log2 = 6;

	local output = "$H$";

	local idx = math.min(iteration_count_log2 + 5, 30) + 1;

	output = output .. itoa64:sub(idx, idx);

	output = output .. hashEncode64(input, 6);

	return output;

end

local function phpbbCheckHash(password, hash)

	if #hash == 32 then return hash == md5(password, true); end -- legacy PHPBB2 hash

	if #hash == 34 then return hashCryptPrivate(password, hash) == hash; end

	if #hash == 60 and have_bcrypt then return bcrypt.verify(password, hash); end

	module:log("error", "Unsupported hash: %s", hash);

	return false;

end

local function phpbbCreateHash(password)

	local random = uuid_gen():sub(-6);

	local salt = hashGensaltPrivate(random);

	local hash = hashCryptPrivate(password, salt);

	if #hash == 34 then return hash; end

	return md5(password, true);

end

provider = {};

function provider.test_password(username, password)

	local hash = get_password(username);

	return hash and phpbbCheckHash(password, hash);

end

function provider.user_exists(username)

	module:log("debug", "test user %s existence", username);

	return get_password(username) and true;

end

function provider.get_password(username)

	return nil, "Getting password is not supported.";

end

function provider.set_password(username, password)

	local hash = phpbbCreateHash(password);

	local stmt, err = setsql("UPDATE `phpbb_users` SET `user_password`=? WHERE `username_clean`=?", hash, username);

	return stmt and true, err;

end

function provider.create_user(username, password)

	return nil, "Account creation/modification not supported.";

end

local escapes = {

	[" "] = "\\20";

	['"'] = "\\22";

	["&"] = "\\26";

	["'"] = "\\27";

	["/"] = "\\2f";

	[":"] = "\\3a";

	["<"] = "\\3c";

	[">"] = "\\3e";

	["@"] = "\\40";

	["\\"] = "\\5c";

};

local unescapes = {};

for k,v in pairs(escapes) do unescapes[v] = k; end

local function jid_escape(s) return s and (s:gsub(".", escapes)); end

local function jid_unescape(s) return s and (s:gsub("\\%x%x", unescapes)); end

function provider.get_sasl_handler()

	local sasl = {};

	function sasl:clean_clone() return provider.get_sasl_handler(); end

	function sasl:mechanisms() return { PLAIN = true; }; end

	function sasl:select(mechanism)

		if not self.selected and mechanism == "PLAIN" then

			self.selected = mechanism;

			return true;

		end

	end

	function sasl:process(message)

		if not message then return "failure", "malformed-request"; end

		local authorization, authentication, password = message:match("^([^%z]*)%z([^%z]+)%z([^%z]+)");

		if not authorization then return "failure", "malformed-request"; end

		authentication = saslprep(authentication);

		password = saslprep(password);

		if (not password) or (password == "") or (not authentication) or (authentication == "") then

			return "failure", "malformed-request", "Invalid username or password.";

		end

		local function test(authentication)

			local prepped = nodeprep(authentication);

			local normalized = jid_unescape(prepped);

			return normalized and provider.test_password(normalized, password) and prepped;

		end

		local username = test(authentication) or test(jid_escape(authentication));

		if not username and params.sessionid_as_password then

			local function test(authentication)

				local prepped = nodeprep(authentication);

				local normalized = jid_unescape(prepped);

				return normalized and check_sessionids(normalized, password) and prepped;

			end

			username = test(authentication) or test(jid_escape(authentication));

		end

		if username then

			self.username = username;

			return "success";

		end

		return "failure", "not-authorized", "Unable to authorize you with the authentication credentials you've sent.";

	end

	return sasl;

end

module:provides("auth", provider);