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)
Because 1.2.3.4 and 1.02.003.04 both map to the same number.
But 10.20.30.40 and 010.020.030.040 map to different numbers. It’s often best to reject IPv4 addresses with leading zeroes to avoid the decimal vs. octal ambiguity.
