1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
|
local md5 = require "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
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]+)")
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
self.username = authentication
if claimed_password == correct_password then
log("debug", "success")
return "success"
else
log("debug", "failure")
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(",$", "")
return data
end
local function parse(data)
message = {}
log("debug", "parse-message: "..data)
for k, v in gmatch(data, [[([%w%-]+)="?([%w%-%/%.%+=]+)"?,?]]) do
message[k] = v
log("debug", " "..k.." = "..v)
end
return message
end
local object = { mechanism = "DIGEST-MD5", realm = realm, password_handler = password_handler}
--TODO: something better than math.random would be nice, maybe OpenSSL's random number generator
object.nonce = generate_uuid()
object.step = 0
object.nonce_count = {}
function object.feed(self, message)
log("debug", "SASL step: "..self.step)
self.step = self.step + 1
if (self.step == 1) then
local challenge = serialize({ nonce = object.nonce,
qop = "auth",
charset = "utf-8",
algorithm = "md5-sess",
realm = self.realm});
log("debug", "challenge: "..challenge)
return "challenge", challenge
elseif (self.step == 2) then
local response = parse(message)
-- check for replay attack
if response["nc"] then
if self.nonce_count[response["nc"]] then return "failure", "not-authorized" end
end
-- check for username, it's REQUIRED by RFC 2831
if not response["username"] then
return "failure", "malformed-request"
end
self["username"] = response["username"]
-- check for nonce, ...
if not response["nonce"] then
return "failure", "malformed-request"
else
-- check if it's the right nonce
if response["nonce"] ~= tostring(self.nonce) then return "failure", "malformed-request" end
end
if not response["cnonce"] then return "failure", "malformed-request", "Missing entry for cnonce in SASL message." end
if not response["qop"] then response["qop"] = "auth" end
if response["realm"] == nil then response["realm"] = "" end
local domain = ""
local protocol = ""
if response["digest-uri"] then
protocol, domain = response["digest-uri"]:match("(%w+)/(.*)$")
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")
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.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;
|