IPアドレスからアドレスクラスとアドレスの種類を求める with Java【2番煎じ】

初めに

クラウドのサーバを使用することになり、ありがたくもグローバルIPを頂けることになった。社内PC(プライベートIP)とクラウドサーバ(グローバルIP)で処理を切り分けるために、IPからアドレスクラスとプライベートIPかを判断できるようにした。

(元ネタ)
IPアドレスからアドレスクラスとアドレスの種類を求める with Java

(参考)
IPアドレス - Wikipedia

実装

IPAddressInfo.java

public class IPAddressInfo {

    public enum AddressClass{
        ClassA(128) {
            @Override
            protected boolean isPrivate(int first, int second) {
                return first == 10;
            }
        },
        ClassB(128 + 64) {
            @Override
            protected boolean isPrivate(int first, int second) {
                return first == 172 && (16 <= second && second <= 31);
            }
        },
        ClassC(128 + 64 + 32) {
            @Override
            protected boolean isPrivate(int first, int second) {
                return first == 192 && second == 168;
            }
        },
        ClassD(128 + 64 + 32 + 16) {
            @Override
            protected boolean isPrivate(int first, int second) {
                return false;
            }
        },
        ClassE(256) {
            @Override
            protected boolean isPrivate(int first, int second) {
                return false;
            }
        },;

        private final int outOfNo;

        /**
         * IPアドレスの5つのアドレスクラス。
         * @param outOfNo 次のアドレスクラスのIPの1つめ
         */
        private AddressClass(int outOfNo){
            this.outOfNo = outOfNo;
        }

        protected abstract boolean isPrivate(int first, int second);
    }

    public AddressClass getAddressClass(int first){
        return  Arrays.stream(AddressClass.values()).filter(p -> first < p.outOfNo).findFirst().orElseThrow(() -> new IllegalArgumentException("IPでない:" + first));
    }

    public AddressClass getAddressClass(String ip){
        List<String> addressList = Arrays.asList(ip.split("\\."));
        return getAddressClass(Integer.valueOf(addressList.get(0)));
    }

    public boolean isPrivate(String ip){
        List<String> addressList = Arrays.asList(ip.split("\\."));
        int first = Integer.valueOf(addressList.get(0));
        int second = Integer.valueOf(addressList.get(1));
        return getAddressClass(first).isPrivate(first, second);
    }
}

テスト

IPAddressInfo.java

    @Test
    public void getAddressClass(){
        assertThat(getAddressClass("0.0.0.0"), is(AddressClass.ClassA));
        assertThat(getAddressClass("10.0.0.0"), is(AddressClass.ClassA));
        assertThat(getAddressClass("10.255.255.255"), is(AddressClass.ClassA));
        assertThat(getAddressClass("127.255.255.255"), is(AddressClass.ClassA));

        assertThat(getAddressClass("128.0.0.0"), is(AddressClass.ClassB));
        assertThat(getAddressClass("172.16.0.0"), is(AddressClass.ClassB));
        assertThat(getAddressClass("172.31.255.255"), is(AddressClass.ClassB));
        assertThat(getAddressClass("191.255.255.255"), is(AddressClass.ClassB));

        assertThat(getAddressClass("192.0.0.0"), is(AddressClass.ClassC));
        assertThat(getAddressClass("192.168.0.0"), is(AddressClass.ClassC));
        assertThat(getAddressClass("192.168.255.255"), is(AddressClass.ClassC));
        assertThat(getAddressClass("223.255.255.255"), is(AddressClass.ClassC));

        assertThat(getAddressClass("224.0.0.0"), is(AddressClass.ClassD));
        assertThat(getAddressClass("239.255.255.255"), is(AddressClass.ClassD));

        assertThat(getAddressClass("240.0.0.0"), is(AddressClass.ClassE));
        assertThat(getAddressClass("255.255.255.255"), is(AddressClass.ClassE));
    }

    @Test
    public void isPrivate(){
        assertThat(isPrivate("0.0.0.0"), is(false));
        assertThat(isPrivate("10.0.0.0"), is(true));
        assertThat(isPrivate("10.255.255.255"), is(true));
        assertThat(isPrivate("127.255.255.255"), is(false));

        assertThat(isPrivate("128.0.0.0"), is(false));
        assertThat(isPrivate("172.16.0.0"), is(true));
        assertThat(isPrivate("172.31.255.255"), is(true));
        assertThat(isPrivate("191.255.255.255"), is(false));

        assertThat(isPrivate("192.0.0.0"), is(false));
        assertThat(isPrivate("192.168.0.0"), is(true));
        assertThat(isPrivate("192.168.255.255"), is(true));
        assertThat(isPrivate("223.255.255.255"), is(false));

        assertThat(isPrivate("224.0.0.0"), is(false));
        assertThat(isPrivate("239.255.255.255"), is(false));

        assertThat(isPrivate("240.0.0.0"), is(false));
        assertThat(isPrivate("255.255.255.255"), is(false));
    }

    @Test(expected=IllegalArgumentException.class)
    public void error(){
        getAddressClass("256.255.255.255");
    }