我在Android上使用Xamarin中的客户端应用程序，我需要TLS 1.2和NTLM。
到目前为止，我一直在使用常规的System.Net.HttpClientHandler并且它工作正常 - 它看起来像这样：
new System.Net.Http.HttpClientHandler()
{
Credentials = credentials
};
但现在我有了一个新客户，我需要TLS 1.2。所以我为Android制作了这个代码：
new Xamarin.Android.Net.AndroidClientHandler()
{
Credentials = credentials
};
使用环境变量：
XA_HTTP_CLIENT_HANDLER_TYPE=Xamarin.Android.Net.AndroidClientHandler
现在，这个AndroidClientHandler可以在证书上运行。但我也需要NTLM才能工作。对我而言，似乎AndroidClientHandler仅支持Basic和Digest身份验证方案（请参阅Xamarin.Android.Net.AuthenticationScheme）。
我也尝试过ModernHttpClient，但在我看来，它使用Mono的方式与System.Net.Http.HttpClientHandler一样，所以TLS 1.2也不能在那里工作。
在我看来，这应该是一个非常常见的情况，但我仍然无法在网上找到相关的例子。我希望我只是遗漏了一些明显的东西。你们是怎么解决这个问题的？
答案 0 :(得分：1)
我相信你阅读是有益的：
/// <para>
/// The class supports pre-authentication of requests albeit in a slightly "manual" way. Namely, whenever a request to a server requiring authentication
/// is made and no authentication credentials are provided in the <see cref="PreAuthenticationData"/> property (which is usually the case on the first
/// request), the <see cref="RequestNeedsAuthorization"/> property will return <c>true</c> and the <see cref="RequestedAuthentication"/> property will
/// contain all the authentication information gathered from the server. The application must then fill in the blanks (i.e. the credentials) and re-send
/// the request configured to perform pre-authentication. The reason for this manual process is that the underlying Java HTTP client API supports only a
/// single, VM-wide, authentication handler which cannot be configured to handle credentials for several requests. AndroidClientHandler, therefore, implements
/// the authentication in managed .NET code. Message handler supports both Basic and Digest authentication. If an authentication scheme that's not supported
/// by AndroidClientHandler is requested by the server, the application can provide its own authentication module (<see cref="AuthenticationData"/>,
/// <see cref="PreAuthenticationData"/>) to handle the protocol authorization.</para>
/// <para>AndroidClientHandler also supports requests to servers with "invalid" (e.g. self-signed) SSL certificates. Since this process is a bit convoluted using
/// the Java APIs, AndroidClientHandler defines two ways to handle the situation. First, easier, is to store the necessary certificates (either CA or server certificates)
/// in the <see cref="TrustedCerts"/> collection or, after deriving a custom class from AndroidClientHandler, by overriding one or more methods provided for this purpose
/// (<see cref="ConfigureTrustManagerFactory"/>, <see cref="ConfigureKeyManagerFactory"/> and <see cref="ConfigureKeyStore"/>). The former method should be sufficient
/// for most use cases, the latter allows the application to provide fully customized key store, trust manager and key manager, if needed. Note that the instance of
/// AndroidClientHandler configured to accept an "invalid" certificate from the particular server will most likely fail to validate certificates from other servers (even
/// if they use a certificate with a fully validated trust chain) unless you store the CA certificates from your Android system in <see cref="TrustedCerts"/> along with
/// the self-signed certificate(s).</para>
基本上这说：它支持Basic和Digest身份验证。如果服务器请求的AndroidClientHandler中不支持认证方案，则应用程序可以提供自己的认证模块来处理协议授权。
然后我们可以看到RequestedAuthentication属性将列出服务器支持的每个方案。：
/// <summary>
/// If the website requires authentication, this property will contain data about each scheme supported
/// by the server after the response. Note that unauthorized request will return a valid response - you
/// need to check the status code and and (re)configure AndroidClientHandler instance accordingly by providing
/// both the credentials and the authentication scheme by setting the <see cref="PreAuthenticationData"/>
/// property. If AndroidClientHandler is not able to detect the kind of authentication scheme it will store an
/// instance of <see cref="AuthenticationData"/> with its <see cref="AuthenticationData.Scheme"/> property
/// set to <c>AuthenticationScheme.Unsupported</c> and the application will be responsible for providing an
/// instance of <see cref="IAndroidAuthenticationModule"/> which handles this kind of authorization scheme
/// (<see cref="AuthenticationData.AuthModule"/>
/// </summary>
这告诉我们，如果它返回Unsupported作为我们的AuthenticationScheme，那么我们需要提交我们自己的IAndroidAuthenticationModule来处理挑战。
以下是AuthenticationScheme：
namespace Xamarin.Android.Net
{
/// <summary>
/// Authentication schemes supported by <see cref="AndroidClientHandler"/>
/// </summary>
public enum AuthenticationScheme
{
/// <summary>
/// Default value used in <see cref="AuthenticationData.Scheme"/>
/// </summary>
None,
/// <summary>
/// <see cref="AndroidClientHandler"/> doesn't support this scheme, the application must provide its own value. See <see cref="AuthenticationData.Scheme"/>
/// </summary>
Unsupported,
/// <summary>
/// The HTTP Basic authentication scheme
/// </summary>
Basic,
/// <summary>
/// The HTTP Digest authentication scheme
/// </summary>
Digest
}
}
因此，我们必须通过在您的实现上扩展此接口来实现自定义IAndroidAuthenticationModule：
然后，您将该实现传递到AuthenticationData.AuthModule属性：
然后，您将其传递到主客户端的PreAuthenticationData属性。
我希望这有帮助！