+-- 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 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 pairs, ipairs = pairs, ipairs;
+local t_insert = table.insert;
local type = type
-local error = error
-local print = print
+local setmetatable = setmetatable;
+local assert = assert;
+local require = require;
module "sasl"
-local function new_plain(realm, password_handler)
- local object = { mechanism = "PLAIN", realm = realm, password_handler = password_handler}
- object.feed = function(self, message)
- log("debug", "feed: "..message)
- 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]+)")
-
- 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
-
- if claimed_password == correct_password then
- return "success", nil
- else
- return "failure", "not-authorized"
- end
- end
- return object
-end
+--[[
+Authentication Backend Prototypes:
+
+state = false : disabled
+state = true : enabled
+state = nil : non-existant
+]]
-local function new_digest_md5(onAuth, onSuccess, onFail, onWrite)
- --TODO maybe support for authzid
+local method = {};
+method.__index = method;
+local mechanisms = {};
+local backend_mechanism = {};
- 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
+-- 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
-
- 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
+
+-- 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
- return message
+ profile.mechanisms = mechanisms;
end
+ return setmetatable({ profile = profile, realm = realm, mechs = mechanisms }, method);
+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)
+-- get a fresh clone with the same realm and profile
+function method:clean_clone()
+ return new(self.realm, self.profile)
+end
- 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
+-- get a list of possible SASL mechanims to use
+function method:mechanisms()
+ return self.mechs;
end
-function new(mechanism, realm, password)
- local object
- 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));
- return nil
+-- select a mechanism to use
+function method:select(mechanism)
+ if not self.selected and self.mechs[mechanism] then
+ self.selected = mechanism;
+ return true;
end
- return object
end
-return _M;
\ No newline at end of file
+-- 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;
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