63 lines
1.5 KiB
C#
63 lines
1.5 KiB
C#
using System;
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using System.Net;
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using System.Linq;
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public class Program
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{
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public static void Main()
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{
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string[] tests = {
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"87.70.141.1/22",
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"36.18.154.103/12",
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"62.62.197.11/29",
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"67.137.119.181/4",
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"161.214.74.21/24",
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"184.232.176.184/18"
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};
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foreach (string t in tests) Console.WriteLine($"{t} => {Canonicalize(t)}");
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}
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static string Canonicalize(string cidr) => CIDR.Parse(cidr).Canonicalize().ToString();
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}
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readonly struct CIDR
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{
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public readonly IPAddress ip;
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public readonly int length;
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public static CIDR Parse(string cidr)
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{
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string[] parts = cidr.Split('/');
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return new CIDR(IPAddress.Parse(parts[0]), int.Parse(parts[1]));
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}
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public CIDR(IPAddress ip, int length) => (this.ip, this.length) = (ip, length);
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public CIDR Canonicalize() =>
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new CIDR(
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new IPAddress(
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ToBytes(
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ToInt(
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ip.GetAddressBytes()
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)
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& ~((1 << (32 - length)) - 1)
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)
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),
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length
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);
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private int ToInt(byte[] bytes) => bytes.Aggregate(0, (n, b) => (n << 8) | b);
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private byte[] ToBytes(int n)
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{
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byte[] bytes = new byte[4];
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for (int i = 3; i >= 0; i--) {
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bytes[i] = (byte)(n & 0xFF);
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n >>= 8;
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}
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return bytes;
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}
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public override string ToString() => $"{ip}/{length}";
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}
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