-- Prosody IM

-- Copyright (C) 2008-2010 Matthew Wild

-- Copyright (C) 2008-2010 Waqas Hussain

-- Copyright (C) 2010 Jeff Mitchell

--

-- This project is MIT/X11 licensed. Please see the

-- COPYING file in the source package for more information.

--

local max = math.max;

local scram_hashers = require "util.sasl.scram".hashers;

local usermanager = require "core.usermanager";

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

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

local hex = require"util.hex";

local to_hex, from_hex = hex.encode, hex.decode;

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

local secure_equals = require "util.hashes".equals;

local log = module._log;

local host = module.host;

local accounts = module:open_store("accounts");

local hash_name = module:get_option_string("password_hash", "SHA-1");

local get_auth_db = assert(scram_hashers[hash_name], "SCRAM-"..hash_name.." not supported by SASL library");

local scram_name = "scram_"..hash_name:gsub("%-","_"):lower();

-- Default; can be set per-user

local default_iteration_count = module:get_option_number("default_iteration_count", 10000);

-- define auth provider

local provider = {};

function provider.test_password(username, password)

	log("debug", "test password for user '%s'", username);

	local credentials = accounts:get(username) or {};

	password = saslprep(password);

	if not password then

		return nil, "Password fails SASLprep.";

	end

	if credentials.password ~= nil and string.len(credentials.password) ~= 0 then

		if not secure_equals(saslprep(credentials.password), password) then

			return nil, "Auth failed. Provided password is incorrect.";

		end

		if provider.set_password(username, credentials.password) == nil then

			return nil, "Auth failed. Could not set hashed password from plaintext.";

		else

			return true;

		end

	end

	if credentials.iteration_count == nil or credentials.salt == nil or string.len(credentials.salt) == 0 then

		return nil, "Auth failed. Stored salt and iteration count information is not complete.";

	end

	local valid, stored_key, server_key = get_auth_db(password, credentials.salt, credentials.iteration_count);

	local stored_key_hex = to_hex(stored_key);

	local server_key_hex = to_hex(server_key);

	if valid and secure_equals(stored_key_hex, credentials.stored_key) and secure_equals(server_key_hex, credentials.server_key) then

		return true;

	else

		return nil, "Auth failed. Invalid username, password, or password hash information.";

	end

end

function provider.set_password(username, password)

	log("debug", "set_password for username '%s'", username);

	local account = accounts:get(username);

	if account then

		account.salt = generate_uuid();

		account.iteration_count = max(account.iteration_count or 0, default_iteration_count);

		local valid, stored_key, server_key = get_auth_db(password, account.salt, account.iteration_count);

		if not valid then

			return valid, stored_key;

		end

		local stored_key_hex = to_hex(stored_key);

		local server_key_hex = to_hex(server_key);

		account.stored_key = stored_key_hex

		account.server_key = server_key_hex

		account.password = nil;

		return accounts:set(username, account);

	end

	return nil, "Account not available.";

end

function provider.user_exists(username)

	local account = accounts:get(username);

	if not account then

		log("debug", "account not found for username '%s'", username);

		return nil, "Auth failed. Invalid username";

	end

	return true;

end

function provider.users()

	return accounts:users();

end

function provider.create_user(username, password)

	if password == nil then

		return accounts:set(username, {});

	end

	local salt = generate_uuid();

	local valid, stored_key, server_key = get_auth_db(password, salt, default_iteration_count);

	if not valid then

		return valid, stored_key;

	end

	local stored_key_hex = to_hex(stored_key);

	local server_key_hex = to_hex(server_key);

	return accounts:set(username, {

		stored_key = stored_key_hex, server_key = server_key_hex,

		salt = salt, iteration_count = default_iteration_count

	});

end

function provider.delete_user(username)

	return accounts:set(username, nil);

end

function provider.get_sasl_handler()

	local testpass_authentication_profile = {

		plain_test = function(_, username, password, realm)

			return usermanager.test_password(username, realm, password), true;

		end,

		[scram_name] = function(_, username)

			local credentials = accounts:get(username);

			if not credentials then return; end

			if credentials.password then

				if provider.set_password(username, credentials.password) == nil then

					return nil, "Auth failed. Could not set hashed password from plaintext.";

				end

				credentials = accounts:get(username);

				if not credentials then return; end

			end

			local stored_key, server_key = credentials.stored_key, credentials.server_key;

			local iteration_count, salt = credentials.iteration_count, credentials.salt;

			stored_key = stored_key and from_hex(stored_key);

			server_key = server_key and from_hex(server_key);

			return stored_key, server_key, iteration_count, salt, true;

		end

	};

	return new_sasl(host, testpass_authentication_profile);

end

module:provides("auth", provider);