如何检查 IP 地址是否在特定子网内

我有一个格式为 10.132.0.0/20 的子网和来自 ASP.Net 请求对象的 IP 地址。

是否有 .NET 框架函数可以检查 IP 地址是否在给定子网内？

如果不能的话，怎么办呢？位操作，我猜？

看一眼使用 C# 计算 IP 地址 https://learn.microsoft.com/en-us/archive/blogs/knom/ip-address-calculations-with-c-subnetmasks-networks在 MSDN 博客上。它包含一个扩展方法（IsInSameSubnet）应该可以满足您的需求以及其他一些好处。

public static class IPAddressExtensions
{
    public static IPAddress GetBroadcastAddress(this IPAddress address, IPAddress subnetMask)
    {
        byte[] ipAdressBytes = address.GetAddressBytes();
        byte[] subnetMaskBytes = subnetMask.GetAddressBytes();

        if (ipAdressBytes.Length != subnetMaskBytes.Length)
            throw new ArgumentException("Lengths of IP address and subnet mask do not match.");

        byte[] broadcastAddress = new byte[ipAdressBytes.Length];
        for (int i = 0; i < broadcastAddress.Length; i++)
        {
            broadcastAddress[i] = (byte)(ipAdressBytes[i] | (subnetMaskBytes[i] ^ 255));
        }
        return new IPAddress(broadcastAddress);
    }

    public static IPAddress GetNetworkAddress(this IPAddress address, IPAddress subnetMask)
    {
        byte[] ipAdressBytes = address.GetAddressBytes();
        byte[] subnetMaskBytes = subnetMask.GetAddressBytes();

        if (ipAdressBytes.Length != subnetMaskBytes.Length)
            throw new ArgumentException("Lengths of IP address and subnet mask do not match.");

        byte[] broadcastAddress = new byte[ipAdressBytes.Length];
        for (int i = 0; i < broadcastAddress.Length; i++)
        {
            broadcastAddress[i] = (byte)(ipAdressBytes[i] & (subnetMaskBytes[i]));
        }
        return new IPAddress(broadcastAddress);
    }

    public static bool IsInSameSubnet(this IPAddress address2, IPAddress address, IPAddress subnetMask)
    {
        IPAddress network1 = address.GetNetworkAddress(subnetMask);
        IPAddress network2 = address2.GetNetworkAddress(subnetMask);

        return network1.Equals(network2);
    }
}