syntax error in $GENERATE crashed all nameservers

Evan Hunt each at
Thu Aug 18 18:09:53 UTC 2011

> No but you're missing the point.   I don't think the OP was and I
> certainly wasn't suggesting it should have done what he "meant" to do.
> However, I DO think it should have errored out because it was invalid
> input.   (That is to say unless you think negative numbers should be
> considered valid input for this command? Please don't respond that
> negative numbers are integers and therefore valid - that would be pure
> sophistry.)

Yes, it's a bug.  It's already in our ticketing system and we will fix it.

The problem is in sscanf(), actually -- I hadn't realized this until now,
but according to C99, the %u (unsigned integer) conversion format will
accept a minus sign in the input without any complaint, and silently
convert the result to a large positive number.  This strikes me as
rather bizarre; I would have expected the conversion to fail, but,

We'll be adding a better formatting check.  Meantime: exercise caution.

Evan Hunt -- each at
Internet Systems Consortium, Inc.

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