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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 type = type
local error = error
local print = print
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
local function new_digest_md5(onAuth, onSuccess, onFail, onWrite)
--TODO maybe 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
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
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
return message
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)
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
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
end
return object
end
return _M;
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