cvs commit: src/lib/libc/resolv res_comp.c

[Doug Barton]

Guy Helmer wrote:

> I've been recently looking at DomainKeys, and underscores appear to be 
> typically used in the domain components for domain keys TXT records 
> (example below from 
> http://www.elandsys.com/resources/sendmail/domainkeys.html):
> 
> mail._domainkey.example.com. IN TXT "k=rsa; t=y;
>           p=MEwwPQRJKoZIhvcNADAQCQADOwAwOAIxANPpYHdE2tevfEpvL1Tk2dDYv0pF28/f5MxU83x/0b
>           sn4R4p7waPaz1IbOGs/6bm5QIDAQAB"

"example.com" is the domain name above. _domainkey.example.com is a 
hostname. There are no TLD registries that accept underscore in domain 
name registrations, but it's extremely difficult to determine reliably 
where the domain name ends and the hostname begins for all TLDs.

This debate is one of the few negative fallouts of the robustness 
principle. Since others have refused to be "conservative in what they 
send" we are forced to be "liberal in what we accept" (as much as I find 
it distasteful on a personal level).

Doug

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