Add support for more java.net.* classes

I’d primarily be interested in support java.net.InetAddress and java.net.InetSocketAddress.

Field type	Factory
InetAddress	InetAddress::getByName
InetAddress[]	InetAddress::getAllByName
InetSocketAddress	InetSocketAddress::new (may need to split on last : of string, or accept a map of hostname and port for construction)

Just for completion’s sake, it may be nice to also support NetworkInterface as that can convert via a string (NetworkInterface::getByName) or an int (NetworkInterface::getByIndex), though I’m not sure how useful it would be in comparison.

[derekmorr]

There are some ways around this:

• the standard library’s InetAddress.getByName() is pure if you pass in an IP address. It only does a DNS lookup if you pass in a hostname.

• As an alternative, there are third-party libraries that only support IP addresses, and will never do a DNS lookup. For example, Guava’s InetAddresses can parse strings like “1.2.3.4” into a java.net.InetAddress - https://google.github.io/guava/releases/20.0/api/docs/com/google/common/net/InetAddresses.html Unfortunately Guava is a very heavyweight library, and I’m not sure it’s worth adding a pureconfig module for it if we’re only going to use a few types.

• If you just want to verify that a string has a vaild hostname, you can use Guava’a InternetDomainName - https://google.github.io/guava/releases/20.0/api/docs/com/google/common/net/InternetDomainName.html. That class has a pure function that just verifies that a string is structurally valid, but doesn’t query DNS to see if it’s nameserved. So, “foo.bar.org” is valid, but “foo!@#.-1.__org” is invalid.

• If you want to verify that an Int is a valid port number you can use refined. It has types for port numbers, system port numbers, user port numbers, etc - https://github.com/fthomas/refined/blob/master/modules/core/shared/src/main/scala/eu/timepit/refined/types/net.scala

I definitely think it’s useful to have pureconfig support for InetAddress. I’m fine using the standard library’s InetAddress helper functions as they’re pure as long as you give the right input.

[LeifW]

Would InetSocketAddress.createUnresolved be an option for this?