[atlas] IPv4 leading zeroes and weird interface behaviour

On 2017-10-25 13:54:46 -0700, Phillip Remaker wrote:
> Historically, C uses a 0 to precede an octal number, 0x to precede a decimal,
> and 0b for binary.

0b for binary is not C. It is used by some other languages, though (e.g. Perl).

> Since 0x is not accepted,

That depends on the tool:

% ping 0x8f.0x82.0x10.0x8
PING 0x8f.0x82.0x10.0x8 (143.130.16.8) 56(84) bytes of data.
64 bytes from 143.130.16.8: icmp_seq=1 ttl=55 time=8.37 ms
64 bytes from 143.130.16.8: icmp_seq=2 ttl=55 time=8.26 ms
...

% ping -V       
ping utility, iputils-s20161105


> There's probably some downstream library making the anachronistic assumption.

Possibly gethostbyname in the libc, but I haven't tested that. At least
interpreting numbers with leading zeroes as octal is traditional on
unix-like OSs (I probably first noticed that on Ultrix around 1990). I
don't know why anyone thought this was a good idea. I wouldn't expect
anyone to rely on it, but apparently nobody dares to get rid of that
"feature".

        hp

-- 
   _  | Peter J. Holzer    | we build much bigger, better disasters now
|_|_) |                    | because we have much more sophisticated
| |   | hjp at hjp.at         | management tools.
__/   | http://www.hjp.at/ | -- Ross Anderson <https://www.edge.org/>
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