Incorrect value for cidr first/last

[ian-hamlin]

Given the following example:

use cidr_utils::cidr::IpCidr;

fn main() {
    let cidr = IpCidr::from_str("100.64.0.0/10");

    match cidr {
        Ok(IpCidr::V4(cidr)) => {
            println!("{:?} {:?}", cidr.first(), cidr.last());
            println!("{:?} {:?}", cidr.first_as_ipv4_addr(), cidr.last_as_ipv4_addr());
            println!("{:?} {:?}", u32::from(cidr.first_as_ipv4_addr()), u32::from(cidr.last_as_ipv4_addr()));
        },
        _ => {},
    }
}

It prints the following:

16484 4294934372 100.64.0.0 100.127.255.255 1681915904 1686110207

The value for cidr last seems wrong, it should be 1686110207

Edit* The value for first also seems wrong, I've updated the example to show the u32 conversions.

[magiclen]

It is not exactly wrong. More precisely, it should be blamed on bad documentation or the API.

The u32 value returned by the first or last methods is used to represent an IPv4 byte array in native byte order (NE). However, u32::from(cidr.first_as_ipv4_addr()) always uses big-endian byte order (BE) to convert the byte array into an u32 value.

It is confusable because IP values are usually stored in big-endian (which is also known as network byte order). I plan to make this crate use BE instead of NE in the next minor version.

[ian-hamlin]

Thank you for the explanation, that makes perfect sense!

[magiclen]

It's done.

[ian-hamlin]

Amazing, thanks.