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local md5 = require "util.hashes".md5;
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
local idna_ascii = require "util.encodings".stringprep.saslprep.to_ascii
module "sasl"
local function new_plain(realm, password_handler)
local object = { mechanism = "PLAIN", realm = realm, password_handler = password_handler}
function object.feed(self, message)
if message == "" or message == nil then return "failure", "malformed-request" end
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]+)")
if authentication == nil or password == nil then return "failure", "malformed-request" end
local password_encoding, correct_password = self.password_handler(authentication, self.realm, "PLAIN")
if correct_password == nil then return "failure", "not-authorized"
elseif correct_password == false then return "failure", "account-disabled" end
local claimed_password = ""
if password_encoding == nil then claimed_password = password
else claimed_password = password_encoding(password) end
self.username = authentication
if claimed_password == correct_password then
return "success"
else
return "failure", "not-authorized"
end
end
return object
end
local function new_digest_md5(realm, password_handler)
--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(",$", "")
return data
end
local function parse(data)
message = {}
for k, v in gmatch(data, [[([%w%-]+)="?([^",]*)"?,?]]) do -- FIXME The hacky regex makes me shudder
message[k] = v
end
return message
end
local object = { mechanism = "DIGEST-MD5", realm = realm, password_handler = password_handler}
--TODO: something better than math.random would be nice, maybe OpenSSL's random number generator
object.nonce = generate_uuid()
object.step = 0
object.nonce_count = {}
function object.feed(self, message)
self.step = self.step + 1
if (self.step == 1) then
local challenge = serialize({ nonce = object.nonce,
qop = "auth",
charset = "utf-8",
algorithm = "md5-sess",
realm = self.realm});
return "challenge", challenge
elseif (self.step == 2) then
local response = parse(message)
-- check for replay attack
if response["nc"] then
if self.nonce_count[response["nc"]] then return "failure", "not-authorized" end
end
-- check for username, it's REQUIRED by RFC 2831
if not response["username"] then
return "failure", "malformed-request"
end
self["username"] = response["username"]
-- check for nonce, ...
if not response["nonce"] then
return "failure", "malformed-request"
else
-- check if it's the right nonce
if response["nonce"] ~= tostring(self.nonce) then return "failure", "malformed-request" end
end
if not response["cnonce"] then return "failure", "malformed-request", "Missing entry for cnonce in SASL message." end
if not response["qop"] then response["qop"] = "auth" end
if response["realm"] == nil then response["realm"] = "" end
local domain = ""
local protocol = ""
if response["digest-uri"] then
protocol, domain = response["digest-uri"]:match("(%w+)/(.*)$")
if protocol == nil or domain == nil then return "failure", "malformed-request" end
else
return "failure", "malformed-request", "Missing entry for digest-uri in SASL message."
end
--TODO maybe realm support
self.username = response["username"]
local password_encoding, Y = self.password_handler(response["username"], response["realm"], "DIGEST-MD5")
if Y == nil then return "failure", "not-authorized"
elseif Y == false then return "failure", "account-disabled" end
local A1 = Y..":"..response["nonce"]..":"..response["cnonce"]--:authzid
local A2 = "AUTHENTICATE:"..protocol.."/"..idna_ascii(domain)
local HA1 = md5(A1, true)
local HA2 = md5(A2, true)
local KD = HA1..":"..response["nonce"]..":"..response["nc"]..":"..response["cnonce"]..":"..response["qop"]..":"..HA2
local response_value = md5(KD, true)
if response_value == response["response"] then
-- calculate rspauth
A2 = ":"..protocol.."/"..idna_ascii(domain)
HA1 = md5(A1, true)
HA2 = md5(A2, true)
KD = HA1..":"..response["nonce"]..":"..response["nc"]..":"..response["cnonce"]..":"..response["qop"]..":"..HA2
local rspauth = md5(KD, true)
self.authenticated = true
return "challenge", serialize({rspauth = rspauth})
else
return "failure", "not-authorized", "The response provided by the client doesn't match the one we calculated."
end
elseif self.step == 3 then
if self.authenticated ~= nil then return "success"
else return "failure", "malformed-request" end
end
end
return object
end
function new(mechanism, realm, password_handler)
local object
if mechanism == "PLAIN" then object = new_plain(realm, password_handler)
elseif mechanism == "DIGEST-MD5" then object = new_digest_md5(realm, password_handler)
else
log("debug", "Unsupported SASL mechanism: "..tostring(mechanism));
return nil
end
return object
end
return _M;
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