> -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED]] > Sent: Tuesday, November 27, 2001 11:52 AM > To: [EMAIL PROTECTED] > Subject: [Sip-implementors] Current date and exipres date > > > Take a look to this scenario. > > A device implements NTP protocol, so it has a device time > (current-time). > The device sends a REGISTER and it receives a 200 OK response in which > there is the "expires" parameter in "Contact" header but > there is not the > "Date" header. > The device must use his current time to compute the expire time. > Now suppose there is an error in NTP server or in Sip server date > so that from the expire date and the current date there are a > long time. > > Example: > Current date: Mon, 26 Nov 2001 01:01:45 GMT (received from NTP) > Expires date: Mon, 26 Nov 2003 02:01:45 GMT (received from Sip Server) > > What the device has to do? > which must be the behaviour of the device in this case ? > > Is it a correct implementation chek the difference between > current date > and expire date and if the difference is larger than one year > it set the expire > time at 3600 seconds (default expire time) ? > > I did not find any item on rfc. > >
I think, in general, any implementation of any protocol has the right to discard obviously broken information. In this particular case, you could easily make such a requirement, and I would even set it to lower, like if its more than a week, roll it back to the default of 3600 seconds. I don't necessarily know if there should be a note in the RFC about it, though. An alternate fix would be to make the expire time value an offset in seconds, so it returns "Expires date: 5000". This fixes the ntp scenario, but broken implementation X could still return "45000000" for the offset, meaning you'd have to set an upper limit on what you will consider a valid response anyway, so you haven't actually gained that much. Thanks, Matt -- Matthew J. Zito Systems Engineer Register.com, Inc., 11th Floor, 575 8th Avenue, New York, NY 10018 Ph: 212-798-9205 PGP Key Fingerprint: 4E AC E1 0B BE DD 7D BC D2 06 B2 B0 BF 55 68 99 _______________________________________________ Sip-implementors mailing list [EMAIL PROTECTED] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
