From: Chris Derrick (cderrick@centenary.edu)
Date: Tue Sep 03 2002 - 08:42:56 CDT
I called ya but you were not there :-(. Let me know when a good time is to come
down there.
me
Robert Lowe wrote:
> "King, Michael" wrote:
>
> The quote below was from me... this was fixed in the CIDR kit. In
> fact, there have been enough minor issues reported, that I would hope
> a new RC would be put forth, whether or not it includes features or
> functionality included in the CIDR kit, or the present alpha OMAPI
> kit.
>
> -Robert
>
> > Eric,
> >
> > I pulled this from the archive.
> >
> > Yes, in the append_host_entry routine, there is a regular expression
> > that matches the username in a dhcpd.conf entry. The code looks like:
> >
> > if ($_ =~ /$FORM{'user'}/) {
> > ($TRASH, $HOST) = split /\s/;
> > push (@HOSTS, $HOST);
> > }
> >
> > It should probably be something like:
> >
> > if (/host $FORM{'user'}-/) {
> >
> > ...
> >
> > Just replace the if line from the top with the one on the bottom. It's
> > remarkable simliar, but there are a few changes. I do not read Perl yet,
> > but it's the next item on my study list.
> >
> > -----Original Message-----
> > From: Eric Gauthier [mailto:elg@bu.edu]
> > Sent: Monday, September 02, 2002 11:22 AM
> > To: netreg@southwestern.edu
> > Subject: NetReg: Counting issue
> >
> > Hello,
> >
> > We encountered a strange problem here at BU that appears related to a bug in
> > the REGEX that figures out how many (if any) hosts a user has already
> > registered. The logic of the script (sub append_host_entry) appears to go
> > like this. First, open the dhcpd.conf file and look to see if the MAC is
> > already registered by searching for the MAC. If they have already
> > registered then stop. Next, open the dhcpd.conf file and find all of the
> > hosts that this user has registered by searching for their username. Look
> > at the last entry that you find. This entry should be listed as
> > <username>-<serial number> so split off the number following the "-",
> > increment by one, and make this the new serial number.
> >
> > Here's the problem we ran into. Student A has a username like "bobsv" and
> > he registers his desktop which now has the host entry "bobsv-1". Student B
> > comes along with a username of "sv" and he registers his desktop. When
> > register.cgi looks through the config file, the REGEX looks for /sv/ and
> > matches "bobsv-1", parses it and increments the serial number to 2, and thus
> > enters Student B's desktop as "sv-2". Now, along comes Student C with a
> > username of "robsv" and he registers his desktop which gets the host entry
> > of "robsv-1". The conf file now looks like:
> > host bobsv-1 ...
> > host sv-2 ...
> > host robsv-1 ...
> > If student B comes back to the system and attempts to register a laptop, the
> > system will look through the config file with the REGEX /sv/ and the last
> > match that it finds is "robsv-1". Register.cgi parses this and increments
> > the serial number to 2 and adds Student B's laptop as "sv-2".
> > Unfortunately, now there are two host entries for "sv-2" with different MAC
> > addresses so when the server reloads there are issues :)
> >
> > The fix appears to be pretty easy. Just modify the REGEX in register.cgi's
> > append_host_entry subroutine to be more explicit. Since none of our
> > hostname's contain a dash ("-"), we do a search for "/^host $FORM{'user'}-/"
> > instead of "/$FORM{'user'}/". Having the match begin with the word "host"
> > followed by a space will prevent it from failing for students who have
> > usernames that are something funky like "ethernet" (or any username that
> > might be a substring of some comment the browser might send in another users
> > registration) and, since none of our usernames have dashes, the trailing "-"
> > in the pattern match should make it only find an exact match for the
> > username. Here's the diff against the script we're testing.
> >
> > 175c175
> > < if ($_ =~ /$FORM{'user'}/) {
> > ---
> > > if ($_ =~ /^host $FORM{'user'}-/) {
> >
> > I'm really not that great at REGEX, so can someone else take a look at this
> > and see if this might also fail in some bizarre way? Or, better yet, has
> > someone else already resolved this?
> >
> > Thanks!
> >
> > Eric Gauthier
> > Network Engineer
> > 617-353-8218 ~^~ elg@bu.edu
> > Boston University - Office of IT
> >
> > **********************************************************************
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> > unsubscribe netreg
> > Send requests for assistance to: owner-netreg@southwestern.edu
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