util/sasl.lua

-- sasl.lua v0.4

-- Copyright (C) 2008-2010 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 pairs, ipairs = pairs, ipairs;

local t_insert = table.insert;

local type = type

local setmetatable = setmetatable;

local assert = assert;

local require = require;

module "sasl"

--[[

Authentication Backend Prototypes:

state = false : disabled

state = true : enabled

state = nil : non-existant

]]

local method = {};

method.__index = method;

local mechanisms = {};

local backend_mechanism = {};

-- register a new SASL mechanims

local function registerMechanism(name, backends, f)

	assert(type(name) == "string", "Parameter name MUST be a string.");

	assert(type(backends) == "string" or type(backends) == "table", "Parameter backends MUST be either a string or a table.");

	assert(type(f) == "function", "Parameter f MUST be a function.");

	mechanisms[name] = f

	for _, backend_name in ipairs(backends) do

		if backend_mechanism[backend_name] == nil then backend_mechanism[backend_name] = {}; end

		t_insert(backend_mechanism[backend_name], name);

	end

end

-- create a new SASL object which can be used to authenticate clients

function new(realm, profile)

	local mechanisms = profile.mechanisms;

	if not mechanisms then

		mechanisms = {};

		for backend, f in pairs(profile) do

			if backend_mechanism[backend] then

				for _, mechanism in ipairs(backend_mechanism[backend]) do

					mechanisms[mechanism] = true;

				end

			end

		end

		profile.mechanisms = mechanisms;

	end

	return setmetatable({ profile = profile, realm = realm, mechs = mechanisms }, method);

end

-- get a fresh clone with the same realm and profile

function method:clean_clone()

	return new(self.realm, self.profile)

end

-- get a list of possible SASL mechanims to use

function method:mechanisms()

	return self.mechs;

end

-- select a mechanism to use

function method:select(mechanism)

	if not self.selected and self.mechs[mechanism] then

		self.selected = mechanism;

		return true;

	end

end

-- feed new messages to process into the library

function method:process(message)

	--if message == "" or message == nil then return "failure", "malformed-request" end

	return mechanisms[self.selected](self, message);

end

-- load the mechanisms

require "util.sasl.plain"     .init(registerMechanism);

require "util.sasl.digest-md5".init(registerMechanism);

require "util.sasl.anonymous" .init(registerMechanism);

require "util.sasl.scram"     .init(registerMechanism);

return _M;