Redundancy

Lately, I've been encountering a loss-of-confidence in the proxying
system whenever it becomes unavailable for any reason. Such reasons
include: System maintenance, the short delay while doing a '-k
reconfigure', log rotation, and the periodic shutdown (to tidy up memory
usage)..not to mention the occasional fault that causes the box to
become unavailable (particularly infrequent, but such things _do_
happen).

These things cause all manner of griping, but more importantly, it
causes people to clear their proxy configurations, and bypass the
system. Now, we don't want to _force_ people to use them, because
occasionally you come across an object that just doesn't load properly
through a proxy (often these have some kind of security doodad that
looks back at the source-ip), and we don't want to unduly restrict the
users in this regard. However, any kind of interruption of service
causes the users to clear their browser's proxy settings, and they don't
remember to put them back later.

I thought about that a _lot_ this afternoon, and sat down and wrote some
code. The end-result is 'sparent 1.1'. It accepts connections. It
doesn't fork. It uses less than 30K of memory, and can be configured as
a sole parent for squid (it only listens to localhost). When it gets a
connection, it tries to forward it to (in turn) each of (up to) five
parents. If a connection succeeds, sparent will forward the connection
traffic through it. If all of them fail, it returns a (somewhat)
customisable HTTP/1.0 error message, and sends an email to the
configured administrator, telling them that the link is down (I found it
a handy feature). Since it's dumb forwarding between connections, it
doesn't care if they're persistant or not. It's happy with either.

It's evil. It's scummy. It's beta. It has no real documentation. Just a
small source file, and a sample config. It also works, within the limits
of my testing. If you're interested, let me know, and I'll bounce a copy
of it out to you.

TODO:
Give connection failure some smarts so that it doesn't email you _every_
time someone tries to connect and everything's unreachable.
Find bugs.
Fix bugs.

D

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