[wip, waiting for proposal] [std] add proper ip address types

[Frixuu]

HaxeFoundation/haxe-evolution#123

This is a very early draft of how I personally imagine hypothetical sys.net improvements might look like. Names and assumptions are subject to change. Posted here in case somebody finds these ramblings useful.

Changes included so far:

• Added sys.net.Ipv4Address. This class has helper methods for creating new IPv4 address objects, stringifying them, parsing, determining address type (link-local? multicast?). For increased compatibility, methods for converting them from/to a little-endian Int are also present. (NAMED INCORRECTLY)
• Added sys.net.Ipv6Address. This class is similar, but works on IPv6 addresses. (NO SCOPE ID SUPPORT IS INCLUDED)
• Added sys.net.IpAddress. This enum holds either an IPv4 or an IPv6 address. I've chosen an enum over a base class/interface for increased ergonomics (cannot miscast, inherit).
• Added sys.net.Dns. I've found most of the current platform-specific implementation of sys.net.Host is resolving and reversing hostnames, so it made sense to me to extract those to a separate module.
• Changed sys.net.Host.
  • This class now has a single target-independent implementation.
  • Added Host.addresses, as a single hostname can be resolved to many addresses at once (e.g. one IPv4 and one IPv6).
• Changed sys.net.Socket implementations.
  • On platforms that appear to support IPv6 (eval, jvm, python) Socket should, in theory, be able to bind and connect to IPv6 interfaces.
  • On platforms that do not support IPv6 (hl, neko) Socket should throw when provided an IPv6 address.
  • Node.js implementation lives in a separate repository and was left unchanged at this time (that's why the build fails).

Changes currently (2024-11) not included, for one reason or another:

• sys.net.Address keeps its name and still can only hold an IPv4 address (as an int).
• No Unix socket addresses capabilities were added.
• sys.net.Socket.bind still accepts a Host, not an IpAddress nor an Address.