* install-rpm, install-tarfile, spewrpmtar.php3, spewrpmtar.in: Pumped
  up even more! The db file we store in /var/db now records both the
  timestamp (of the file, or if remote the install time) and the MD5
  of the file that was installed. Locally, we can get this info when
  accessing the file via NFS (copymode on or off). Remote, we use wget
  to get the file, and so pass the timestamp along in the URL request,
  and let spewrpmtar.in determine if the file has changed. If the
  timestamp it gets is >= to the timestamp of the file, an error code
  of 304 (Not Modifed) is returned. Otherwise the file is returned.

  If the timestamps are different (remote, server sends back an actual
  file), the MD5 of the file is compared against the value stored. If
  they are equal, update the timestamp in the db file to avoid
  repeated MD5s (or server downloads) in the future. If the MD5 is
  different, then reinstall the tarball or rpm, and update the db file
  with the new timestamp and MD5. Presto, we have auto update capability!

  Caveat: I pass along the old MD5 in the URL, but it is currently
  ignored. I do not know if doing the MD5 on the server is a good
  idea, but obviously it is easy to add later. At the moment it
  happens on the node, which means wasted bandwidth when the timestamp
  has changed, but the file has not (probably not something that will
  happen in typical usage).

  Caveat: The timestamp used on remote nodes is the time the tarfile
  is installed (GM time of course). We could arrange to return the
  timestamp of the local file back to the node, but that would mean
  complicating the protocol (or using an http header) and I was not in
  the mood for that. In typical usage, I do not think that people will
  be changing tarfiles and rpms so rapidly that this will make a
  difference, but if it does, we can change it.

* node_update.in, client side watchdog, and various web pages:
  Deflated node_update, removing all of the older ssh code. We now
  assume that all nodes will auto update on a periodic basis, via the
  watchdog that runs on all client nodes, including plab nodes.

  Changed the permission check to look for new UPDATE permission (used
  to be UPDATEACCOUNT). As before, it requires local_root or better.
  The reason for this is that node_update now implies more than just
  updating the accounts/mounts. The web pages have been changed to
  explain that in addition to mounts/accounts, rpms and tarfiles will
  also be updated. At the moment, this is still tied to a single
  variable (update_accounts) in the nodes table, but as Kirk requested
  at the meeting, it will probably be nice to split these out in the
  future.

  Added the ability to node_update a single node in an experiment (in
  addition to all nodes option on the showexp page). This has been
  added to the shownode webpage menu options.

  Changed locking code to use the newer wrapper states, and to move
  the experiment to RUNNING_LOCKED until the update completes. This is
  to prevent mayhem in the rest of the system (which could be dealt
  with, but is not worth the trouble; people have to wait until their
  initiated update is complete, before they can swap out the
  experiment).

  Added "short" mode to shownode routine, equiv to the recently added
  short mode for showexp. I use this on the confirmation page for
  updating a single node, giving the user a couple of pertinent (feel
  good) facts before they comfirm.

Chad's tiptunnel stuff. Requires ssh-mime.pl in the current directory,
to be installed as a browser helper application on the users machine.
Copied Chad's instructions for the tiptunnel from the FAQ, and stuck
it into ssh-mime.html as a help file (not really FAQ material). The
intent of this of course is to make ssh into jailed nodes easier, but
not having to know port numbers, or directly log into ops first, when
the jails are using control network IPs in our private IP space (not
routable from outside).

Better headers on shownode page,
also added "Project" prefix to header on showproject and
"Experiment" prefix to header on showexp.

Serial Line' option.

Added faq entry, added script to generate acl files, and added
menu option (With "howto" link to FAQ") to shownode.

information page. Got tired of having to past the them all by hand
between windows. Only admins can do this.

Also, add subpage menu stuff to make the page look nicer.

supporting autocreating and autoloading images. The imageid form now
sports a field to specify a nodeid to create the image from; If set,
the backend create_image script is invoked. Thats the easy part.
Slightly harder is autoloading images based on the osid specified in
the NS file. To support this, I have added a new DB table called
osidtoimageid, which holds the mapping from osid/pctype to imageid.
When users create images, they must specify what node types that image
is good for. Obviously, the mappings have to be unique or it would be
impossible to figure it out! Anyway, once that image mapping is
in place and the image created, the user can specify that ID in the NS
file. I've changed os_setup to to look for IDs that are not loaded,
and to try and find one in the osidtoimageid. If found, it invokes
os_load. To keep things running in parallel as much as possible,
os_setup issues all the loads/reboots (could be more than a single set
of loads is multiple IDs are in the NS file) at once, and waits for
all the children to exit. I've hacked up os_load a bit to try and be
more robust in the face of PXE failures, which still happen and are
rather troublsesome. Need an event system!

Contained in this revision are unrelated changed to make the OS and
Image IDs per-project unique instead of globally unique, since thats a
pain for the users. This turns out to be very messy, since underneath
we do not want to pass around pid/ID in all the various places its
used. Rather, I create a globally unique name and extened the OS and
Image tables to include pid/name/ID. The user selects pid/name, and I
create the globally unique ID. For the most part this is invisible
throughout the system, except where we interface with the user, say in
the web pages; the user should see his chosen name where possible, and
the should invoke scripts (os_load, create_image, etc) using his/her
name not the internal ID. Also, in the front end the NS file should
use the user name not the ID. All in all, this accounted for a number
of annoying changes and some special cases that are unavoidable.

viewing the log.