0.0.0.0/0
::
0.0.0.0/0 0::0/0
You didn’t specify it couldn’t be in CIDR block notation…
Remember, when we abbreviate an ipv6 address all leading zeros are reduced to a single 0.
E.g
0003 would just become 03
When there are geoups of 4 zeros these can be represented as a single 0 or as a double colon ::
But we can only use the :: once so when summarizing an address containing multiple groups of 4 0s one after the other they can all be abbreviated to a single ::
Eg
fe80:0000:0000:0000:0210:5aff:feaa:20a2 would become fe80::210:5aff:feaa:20a2
Therefore it is perfectly valid to abbreviate an address of 0000:0000:0000:0000:0000:0000:0000:0000 /0 to just ::/0
Ok. This covers every ipv6 and ipv4 address.
“^\s*((([0-9A-Fa-f]1,4}:){7}([0-9A-Fa-f]{1,4}:)6}(:[0-9A-Fa-f]{1,4})|:))|(([0-9A-Fa-f]1,4}:){5}(((:[0-9A-Fa-f]{1,4}){1,2}))|:))|(([0-9A-Fa-f]1,4}:){4}(((:[0-9A-Fa-f]{1,4}){1,3}))?:((25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9]?[0-9])(.(25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9]?[0-9]))3})):)3}(((:[0-9A-Fa-f]{1,4}){1,4}))0,2}:((25[0-5]))|:))|(([0-9A-Fa-f]1,4}:){2}(((:[0-9A-Fa-f]{1,4}){1,5}))0,3}:((25[0-5]))|:))|(([0-9A-Fa-f]1,4}:){1}(((:[0-9A-Fa-f]{1,4}){1,6}))0,4}:((25[0-5]))|:))|(:(((:[0-9A-Fa-f]1,4}){1,7}))0,5}:((25[0-5]))|:)))(%.+)?\s*$”
That would allow for like, 2 trillion devices? Feels like a bandaid, my dude. Next you’re gonna suggest a giant ice cube in the ocean once a year to stop global warming.
So add two more octets:
Moat companies will still just use something like 10.0.13.37.0.1
You could follow this logic and add 2 alphanumeric digits before 4 numeric octets. E.g. xf.192.168.1.1
This would at least keep it looking like an IP and not a Mac address. Another advantage would be graceful ipv4 handling with a reserved range starting with “ip” like ip.10.10.10.1
Oh yeah, great, let’s change the fundamental protocol on which all the networks in the world are based. Now two third of the devices in the world crashed because you tried to ping 192.168.0.0.1
Please don’t. Use regex to find something that looks like an IP then build a real parser. This is madness, its’s extremely hard to read and a mistake is almost impossible to spot. Not to mention that it’s slow.
Just parse [0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3} using regex (for v4) and then have some code check that all the octets are valid (and store the IP as a u32).
And dupe check. 0.0.0.0 and 000.000.000.000 may both be valid, but they resolve the same
Fuck that, if for whatever reason I’m writing an IP validator by hand I’m disallowing leading zeros. Parsers are very inconsistent, some will parse 010 as 10, others as 0o10 == 8 (you can try that right now with a POSIX ping). Talk about a footgun.
Definitely, tho if you store it as a u32 that is fixed magically. Because 1.2.3.4 and 1.02.003.04 both map to the same number.
What I mean by storing it as a u32 is to convert it to a number, similar to how the IP gets sent over the wire, so for v4:
octet[3] | octet[2] << 8 | octet[1] << 16 | octet[0] << 24
or in more human terms:
(fourth octet) + (third octet * 256) + (second octet * 256^2) + (first octet * 256^3)
Made that joke in an interview once.
They didn’t think it was funny. They truly thought Regex was the solution to, but never the cause of, all problems.
They wanted to make a Regex to verify every single address in the world. Dodged a bullet
Holy hell yeah you did. How would you go about doing that in a single expression? A bunch of back references to figure out the country? What if that’s not included? Oy.
