[ipxe-devel] Unable to resolve CNAME

Michael Brown mcb30 at ipxe.org
Wed Feb 26 16:19:31 UTC 2014

On 19/02/14 22:20, Nicolas Sylvain wrote:
> After a few months without updating my iPXE binary, I updated it and now
> I'm unable to resolve any CNAME.

Should now be fixed:


> www.cnn.com <http://www.cnn.com> fails as well, but this one because of
> a "recursion exceeded".

Turns out to be the same problem.  The bug related to not properly 
recalculating the length of the name after receiving a CNAME record.  In 
the case of "storage.googleapis.com", this resulting in iPXE attempting 
to look up "storage-ugc.l.googleus" (truncated to the length of 
"storage.googleapis.com").  In the case of "www.cnn.com", it resolves to 
"www.cnn.com.vgtf.net"; truncating this to the length of "www.cnn.com" 
gives exactly "www.cnn.com", hence the eventual "recursion exceeded" error.

The problem occurs only when the CNAME is longer than the original name, 
which is how this managed to slip through testing.

Thanks for reporting the problem, and with enough detail to allow me to 
reproduce it quickly!


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