我的问题基本上与这里描述的一致 这里。

简而言之：对需要客户端证书的服务器发起的网络请求，在我使用PowerShell或 Postman时可以工作，或者在把BurpSuite作为代理并配置了客户端证书时也可以工作。当我使用 HttpClient 搭配一个 HttpClientHandler 时则无法工作。错误信息是：

System.Net.Http.HttpRequestException: An error occurred while sending the request.
System.Net.Http.HttpIOException: The response ended prematurely. (ResponseEnded)

at System.Net.Http.HttpConnection.SendAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
--- End of inner exception stack trace ---
at System.Net.Http.HttpConnection.SendAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
at System.Net.Http.HttpConnectionPool.SendWithVersionDetectionAndRetryAsync(HttpRequestMessage request, Boolean async, Boolean doRequestAuth, CancellationToken cancellationToken)
at System.Net.Http.DiagnosticsHandler.SendAsyncCore(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
at System.Net.Http.RedirectHandler.SendAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
at System.Net.Http.SocketsHttpHandler.g__CreateHandlerAndSendAsync|115_0(HttpRequestMessage request, CancellationToken cancellationToken)
at System.Net.Http.HttpClient.g__Core|83_0(HttpRequestMessage request, HttpCompletionOption completionOption, CancellationTokenSource cts, Boolean disposeCts, CancellationTokenSource pendingRequestsCts, CancellationToken originalCancellationToken)
at Program.Main(String[] args) in D:\repos\ConsoleApp1\Program.cs:line 39

链接的帖子中的答案是用 HttpClientHandler 替换为 SocketsHttpHandler，在一个简单的控制台应用程序中这对我有效。

唯一的问题是，实际上我正在处理一个使用RestSharp的代码库，而RestSharp在内部使用 HttpClientHandler。

我的问题是：

• 我能否绕过RestSharp使用的 HttpMessageHandler？
• 有没有办法让它与 HttpClientHandler 一起工作？

FWIW这是我用于测试的代码：

using var store = new X509Store(StoreLocation.LocalMachine);
store.Open(OpenFlags.ReadOnly);

var certs = store.Certificates.Find(X509FindType.FindBySubjectDistinguishedName, "CN=example.com", true);
var cert = certs[0];

// I also tried this, makes no difference
// var cert = X509CertificateLoader.LoadPkcs12FromFile(@"C:\data\cert.pfx", "password");

using var handler = new HttpClientHandler();
handler.ClientCertificates.Add(cert);

// The following 2 lines make it work
// using var handler = new SocketsHttpHandler();
// handler.SslOptions.ClientCertificates = [cert];

using var client = new HttpClient(handler);
var response = await client.GetAsync("https://example.com/path"); // <== exception is raised here

解决方案

也许你应该试试这个：

var options = new RestClientOptions("https://example.com/endpoint")
{
    ConfigureMessageHandler = _ => new SocketsHttpHandler()
    {
        SslOptions = new SslClientAuthenticationOptions()
        {
            ClientCertificates = cert
        }
        // more config options for SocketsHttpHandler can be added, if any
    }
};

var client = new RestClient(options); // originally "https://example.com/endpoint"

说明：

• RestSharp的 RestClient 构造函数可以接受一个 RestClientOptions 对象，而不是它的常规用法，即端点URL。这样的 RestClientOptions 对象本身具有一个 ConfigureMessageHandler 属性，允许你更改处理程序，它应该是一个返回 HttpMessageHandler 类对象的lambda，或者它的派生类对象。而 SocketsHttpHandler 恰好是它的派生类，所以我们有办法对其进行挂钩。
• 我自己没有亲自试过，看看它是否能解决你所说的“RespondEnded”错误，因为我确实无法访问你的系统。如果确实使用 SocketsHttpHandler 能像你在直接用它的简单控制台程序中测试时那样解决问题，那么值得你去尝试。