Java IPAddress 库和非零 CIDR

Question

I am using Sean Foley's Java library IPAddress and I'm running into an issue generating IPs from a CIDR. IPAddress does not consider 10.90.6.14/30 a CIDR and addr.isMultiple() returns false.

Our legacy code (Golang) and a couple of online CIDR calculators I've tried return:

10.90.6.12 10.90.6.13 10.90.6.14 10.90.6.15

Can anyone advise me on how to achieve this result using the IPAddress library?

Answer 1

The author of the IPAddress library, Sean Foley, was kind enough to post this answer on the github site (thank you Sean:):

In summary, 10.90.6.14/30 is the same as 10.90.6.14 because the host is not zero. 10.90.6.12/30 is the subnet of 4 addresses because the host is zero. If you want to convert to the subnet, then use toPrefixBlock.

list(new IPAddressString("10.90.6.12/30").getAddress());
list(new IPAddressString("10.90.6.14/30").getAddress().toPrefixBlock());

static void list(IPAddress addr) { System.out.println(addr + " has count " + addr.getCount()); for(IPAddress addr2: addr.getIterable()) { System.out.println(addr2); } System.out.println(); } Output:

10.90.6.12/30 has count 4 10.90.6.12/30 10.90.6.13/30 10.90.6.14/30 10.90.6.15/30

10.90.6.12/30 has count 4 10.90.6.12/30 10.90.6.13/30 10.90.6.14/30 10.90.6.15/30