Similarly, browsers also accept IP addresses in decimal form, for example http://16843009 for 1.1.1.1
Sadly, cloudflare does not.
The syntax rule for host is ambiguous because it does not completely
distinguish between an IPv4address and a reg-name. In order to
disambiguate the syntax, we apply the "first-match-wins" algorithm:
If host matches the rule for IPv4address, then it should be
considered an IPv4 address literal and not a reg-name.
Some things do definitely try to follow RFC 3986 still, but my feeling is that it’s mostly legacy stuff, and the URL Standard is much more important these days. Though RFCs dealing with URLs will probably still cite it (e.g. RFC 9110, HTTP Semantics, June 2022).
https://url.spec.whatwg.org/#host-parsing, follow step seven.
Huh, in many years of web development I never knew that. Thanks!
IP address p.q.r.s is decimal p256^3+q256^2+r*256+s.
Or maybe in your terms it's 256^(0..3) where you can think of it like each dotted component is a symbol (like 0-9 in base 10) where each component is a position digit. Where the right-most element is the "256^0" ("ones") digit, and the left most element is the "256^3" ("16,777,216s") digit.
Remove the dots and concat the binary value for 1.1.1.1 and you get 00000001000000010000000100000001.
Convert that binary value to decimal and you get 16843009.
16843009