Question

我正在尝试确定给定的IPv6地址在C＃中是否是私有的，我很想在IPAddress类上使用'IsIPv6SiteLocal'属性。但是，如此comment中所述，不推荐使用此属性中实现的逻辑。我运行了以下单元测试：

[TestMethod]
public void IsPrivate_ipv6_True()
{
    // This sample private IPv6 address was generated using: http://unique-local-ipv6.com/
    var ip = IPAddress.Parse("fd44:fda4:e1ba::1");
    Assert.IsTrue(ip.IsIPv6SiteLocal);
}

单元测试中的断言失败，确认IsIPv6SiteLocal无法正确确定地址是否为本地。所以我需要一个替代方案。

我编写了以下扩展方法，我想知道是否有人能够想到一个不能正确判断地址是私有/公共的情况。

public static bool IsPrivateIPv6(this IPAddress address)
{
    var addressAsString = address.ToString();
    var firstWord = addressAsString.Split(new[] { ':' }, StringSplitOptions.RemoveEmptyEntries)[0];

    // Make sure we are dealing with an IPv6 address
    if (address.AddressFamily != AddressFamily.InterNetworkV6) return false;

    // The original IPv6 Site Local addresses (fec0::/10) are deprecated. Unfortunately IsIPv6SiteLocal only checks for the original deprecated version:
    else if (address.IsIPv6SiteLocal) return true;

    // These days Unique Local Addresses (ULA) are used in place of Site Local. 
    // ULA has two variants: 
    //      fc00::/8 is not defined yet, but might be used in the future for internal-use addresses that are registered in a central place (ULA Central). 
    //      fd00::/8 is in use and does not have to registered anywhere.
    else if (firstWord.Substring(0, 2) == "fc" && firstWord.Length >= 4) return true;
    else if (firstWord.Substring(0, 2) == "fd" && firstWord.Length >= 4) return true;

    // Link local addresses (prefixed with fe80) are not routable
    else if (firstWord == "fe80") return true;

    // Discard Prefix
    else if (firstWord == "100") return true;

    // Any other IP address is not Unique Local Address (ULA)
    else return false;
}

EDITED 2/13/2016 ：

确保第一个单词长度至少为4个字符，如@RonMaupin
根据@RonMaupin
根据@KevinBurdett
检查@KevinBurdett

Answer 1

虽然不是特别优雅......但我真的无法想到更好的事情：）

但是，我还会检查链接本地地址，前缀为fe80:。它们不可路由，但如果您直接从接口提取IP，则当没有其他IPv6地址时，它仍然可以报告本地链接。

关于IPv6的维基百科文章（https://en.wikipedia.org/wiki/Reserved_IP_addresses#IPv6）也将100:显示为丢弃前缀。根据您要完成的任务，您可能还需要检查这些内容。

Answer 2

通过为::1添加一个特殊案例并从他的解决方案中避免ArgumentException（将在Substring()调用中发生）来改进@ desautelsj的答案：

public static bool IsPrivateIPv6(IPAddress address)
{
    // Make sure we are dealing with an IPv6 address
    if (address.AddressFamily != AddressFamily.InterNetworkV6)
        throw new ArgumentException("IP address is not V6", "address");

    var addressAsString = address.ToString();
    var firstWord = addressAsString.Split(new[] { ':' }, StringSplitOptions.RemoveEmptyEntries)[0];

    // equivalent of 127.0.0.1 in IPv6
    if (addressAsString == "::1")
        return true;

    // The original IPv6 Site Local addresses (fec0::/10) are deprecated. Unfortunately IsIPv6SiteLocal only checks for the original deprecated version:
    else if (address.IsIPv6SiteLocal)
        return true;

    // These days Unique Local Addresses (ULA) are used in place of Site Local. 
    // ULA has two variants: 
    //      fc00::/8 is not defined yet, but might be used in the future for internal-use addresses that are registered in a central place (ULA Central). 
    //      fd00::/8 is in use and does not have to registered anywhere.
    else if (firstWord.Length >= 4 && firstWord.Substring(0, 2) == "fc")
        return true;
    else if (firstWord.Length >= 4 && firstWord.Substring(0, 2) == "fd")
        return true;

    // Link local addresses (prefixed with fe80) are not routable
    else if (firstWord == "fe80")
        return true;

    // Discard Prefix
    else if (firstWord == "100")
        return true;

    // Any other IP address is not Unique Local Address (ULA)
    return false;
}

在F＃中：

let private IsIpv6AddressPrivate (address: IPAddress) =
    if (address.AddressFamily = AddressFamily.InterNetwork) then
        invalidArg "address" "address must be IPv6"

    // The original IPv6 Site Local addresses (fec0::/10) are deprecated. Unfortunately IsIPv6SiteLocal only checks for the original deprecated version:
    else if (address.IsIPv6SiteLocal) then
        true
    else
        let addressAsString = address.ToString()

        // equivalent of 127.0.0.1 in IPv6
        if (addressAsString = "::1") then
            true
        else
            let firstWord = addressAsString.Split([|':'|], StringSplitOptions.RemoveEmptyEntries).[0]
            // These days Unique Local Addresses (ULA) are used in place of Site Local. 
            // ULA has two variants: 
            //      fc00::/8 is not defined yet, but might be used in the future for internal-use addresses that are registered in a central place (ULA Central). 
            //      fd00::/8 is in use and does not have to registered anywhere.
            if (firstWord.Length >= 4 && firstWord.Substring(0, 2) = "fc") ||
               (firstWord.Length >= 4 && firstWord.Substring(0, 2) = "fd") ||
               // Link local addresses (prefixed with fe80) are not routable
               (firstWord = "fe80") ||
               // Discard Prefix
               (firstWord = "100") then
                true
            else
                false

Answer 3

这是我使用的最终代码，到目前为止似乎按预期工作：

public static bool IsPrivateIPv6(this IPAddress address)
{
    var addressAsString = address.ToString();
    var firstWord = addressAsString.Split(new[] { ':' }, StringSplitOptions.RemoveEmptyEntries)[0];

    // Make sure we are dealing with an IPv6 address
    if (address.AddressFamily != AddressFamily.InterNetworkV6) return false;

    // The original IPv6 Site Local addresses (fec0::/10) are deprecated. Unfortunately IsIPv6SiteLocal only checks for the original deprecated version:
    else if (address.IsIPv6SiteLocal) return true;

    // These days Unique Local Addresses (ULA) are used in place of Site Local. 
    // ULA has two variants: 
    //      fc00::/8 is not defined yet, but might be used in the future for internal-use addresses that are registered in a central place (ULA Central). 
    //      fd00::/8 is in use and does not have to registered anywhere.
    else if (firstWord.Substring(0, 2) == "fc" && firstWord.Length >= 4) return true;
    else if (firstWord.Substring(0, 2) == "fd" && firstWord.Length >= 4) return true;

    // Link local addresses (prefixed with fe80) are not routable
    else if (firstWord == "fe80") return true;

    // Discard Prefix
    else if (firstWord == "100") return true;

    // Any other IP address is not Unique Local Address (ULA)
    else return false;
}

如何确定IPv6地址是否为私有？

3 个答案: