--=========================
--SASL DIGEST-MD5 according to RFC 2831
+local function new_digest_md5(realm, credentials_handler)
+ --TODO complete 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["realm"] then data = data..[[realm="]]..message.realm..[[",]] end
+ 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["rspauth"] then data = data..[[rspauth=]]..message.rspauth.."," end
+ data = data:gsub(",$", "")
+ return data
+ end
+
+ local function utf8tolatin1ifpossible(passwd)
+ local i = 1;
+ while i <= #passwd do
+ local passwd_i = to_byte(passwd:sub(i, i));
+ if passwd_i > 0x7F then
+ if passwd_i < 0xC0 or passwd_i > 0xC3 then
+ return passwd;
+ end
+ i = i + 1;
+ passwd_i = to_byte(passwd:sub(i, i));
+ if passwd_i < 0x80 or passwd_i > 0xBF then
+ return passwd;
+ end
+ end
+ i = i + 1;
+ end
+
+ local p = {};
+ local j = 0;
+ i = 1;
+ while (i <= #passwd) do
+ local passwd_i = to_byte(passwd:sub(i, i));
+ if passwd_i > 0x7F then
+ i = i + 1;
+ local passwd_i_1 = to_byte(passwd:sub(i, i));
+ t_insert(p, to_char(passwd_i%4*64 + passwd_i_1%64)); -- I'm so clever
+ else
+ t_insert(p, to_char(passwd_i));
+ end
+ i = i + 1;
+ end
+ return t_concat(p);
+ end
+ local function latin1toutf8(str)
+ local p = {};
+ for ch in gmatch(str, ".") do
+ ch = to_byte(ch);
+ if (ch < 0x80) then
+ t_insert(p, to_char(ch));
+ elseif (ch < 0xC0) then
+ t_insert(p, to_char(0xC2, ch));
+ else
+ t_insert(p, to_char(0xC3, ch - 64));
+ end
+ end
+ return t_concat(p);
+ end
+ local function parse(data)
+ local 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, credentials_handler = credentials_handler};
+
+ 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 or response["realm"] == "" then
+ response["realm"] = "";
+ elseif response["realm"] ~= self.realm then
+ return "failure", "not-authorized", "Incorrect realm value";
+ end
+
+ local decoder;
+ if response["charset"] == nil then
+ decoder = utf8tolatin1ifpossible;
+ elseif response["charset"] ~= "utf-8" then
+ return "failure", "incorrect-encoding", "The client's response uses "..response["charset"].." for encoding with isn't supported by sasl.lua. Supported encodings are latin or utf-8.";
+ 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.credentials_handler("DIGEST-MD5", response["username"], self.realm, response["realm"], decoder);
+ if Y == nil then return "failure", "not-authorized"
+ elseif Y == false then return "failure", "account-disabled" end
+ local A1 = "";
+ if response.authzid then
+ if response.authzid == self.username.."@"..self.realm then
+ -- COMPAT
+ log("warn", "Client is violating XMPP RFC. See section 6.1 of RFC 3920.");
+ A1 = Y..":"..response["nonce"]..":"..response["cnonce"]..":"..response.authzid;
+ else
+ A1 = "?";
+ end
+ else
+ A1 = Y..":"..response["nonce"]..":"..response["cnonce"];
+ end
+ local A2 = "AUTHENTICATE:"..protocol.."/"..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.."/"..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
+
return _M;
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