Re: Fix IPV6 literal notation?

[Nick Hilliard <[e-mail]>]

Brian E Carpenter wrote on 28/12/2020 20:44:
> I think that's really not needed. As a matter of curiosity, I think
> the IPv4 format is pretty much undocumented. A few minutes of research
> found this:
> 
>     One commonly used notation for internet host addresses divides the
>     32-bit address into four 8-bit fields and specifies the value of each
>     field as a decimal number with the fields separated by periods.  This
>     is called the "dotted decimal" notation.  For example, the internet
>     address of ISIF in dotted decimal is 010.002.000.052, or 10.2.0.52.
> 
> which first appeared in RFC820 (January 1983) and last appeared in
> RFC990 (November 1986). Note that leading zeroes are allowed and do not
> signal octal.

it's not unprecedented that programs emit or expect leading zeros when 
dealing with dotted decimal ipv4 notation. You tend to get this quite a 
bit with embedded ip stacks, e.g. rom monitors, bootloaders, PXE 
front-ends, etc.

Obviously this conflicts with the behaviour that you'll see in 
bsd-derived parsers, so in general it's a bad idea to use leading zeros. 
  The same thing applies to using dotted hex, mixing octal/decimal/hex 
format, and partial/complete non-dotted format. Sometimes addresses 
written in these formats will do what you intend, but depending on 
consistent interpretation would be brave, to say the least.

Nick