DNS related Assertions with Tor 0.1.2.1-alpha

[Nick Mathewson]

On Wed, Sep 20, 2006 at 12:15:27PM +0200, Fabian Keil wrote:
> With Tor 0.1.2.1-alpha running on FreeBSD 7.0-CURRENT
> my exit nodes used to hit:
> 
> [err] dns.c:596: dns_cancel_pending_resolve: Assertion ! resolve->expire failed; aborting.
> 

Okay; we've had a fix for this one in the subversion repository for
while; the fix should come out in the next alpha. 

> several times a day, until I replaced the assertion with
> a simple warning. Before the assertion is triggered,
> launch_resolve() always complaints about:
> 
> 'eventdns rejected address "$URL": error 1.'
> 
> $URL always is a complete urlencoded URL
> and never a valid host name as it's supposed to be.
> 
> While this isn't Tor's fault, I think it would make
> sense if the Tor client did some simple URL sanity
> checks before passing forward any requests. From time to
> time these broken URLs contain usernames and passwords.

That's quite weird; it looks like somebody is trying to resolve URLs
rather than hostnames. How bizarre!

Ordinarily, this shouldn't be showing up in your log unless you have
SafeLogging turned off, or unless we screwed it up in 0.1.2.1-alpha
(it works now).

But yeah, I agree that we should check that hostnames are plausible
before trying to resolve them.  I'll add that to the 0.1.2.x TODO
list.


> Another assertion that I only got once so far is:
> 
> [err] purge_expired_resolves(): The expired resolve we purged didn't match any in the cache. Tried to purge delb.myspace.com (0xb948200); instead got delb.myspace.com (0x804b99c).
> [err] dns.c:319: purge_expired_resolves: Assertion removed == resolve failed; aborting.

I think we solved this one too, but let me know if it comes back,
especially after the next alpha release is out.  A stack trace there
might be really handy.

yrs,
-- 
Nick Mathewson
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