我试图确定给定的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，此属性中实现的逻辑已弃用。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。所以我需要另一种选择。
我编写了以下扩展方法，我想知道是否有人可以想到一个不能正确确定地址是私有/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;
}
2016年2月13日编辑：
虽然不是特别优雅......我真的想不出更好的:)
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，则在没有其他IPv6地址时，它仍可能会报告本地链接。
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。
通过为::1添加一个特殊情况并从他的解决方案中避免ArgumentException来改进@ desautelsj的答案（这将在Substring()调用中发生）：
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
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;
}