Aditya Garg <gargaditya08@xxxxxxxx> writes:
>> * ... but I don't know if your use of negative lookaround
>> assersions is correct. Shouldn't the "a label cannot begin or
>> end with dash" be applied not just to the first label but
>> consistently to all of the dot-separated labels?
>
> I think you are talking about this case:
>
> someone.-example.com
>
> No, its not valid.a
I was not talking about any "case"; I was talking more about your
regexp to catch invalid addresses. From RFC 5321,
helo = "HELO" SP Domain CRLF
Domain = sub-domain *("." sub-domain)
sub-domain = Let-dig [Ldh-str]
Let-dig = ALPHA / DIGIT
Ldh-str = *( ALPHA / DIGIT / "-" ) Let-dig
so the syntax for first "sub-domain" applies equally to the other
"sub-domain". If "-example" cannot be the third-level subdomain,
then it equally cannot be the second-level, either, but IIRC, the
patch had regexp that treated the first level differently from the
rest.
