Xamarin.Forms HTTPS 和自签名证书问题

Question

我正在使用 Xamarin.Forms，我的优先级是 UWP。我正在尝试通过System.Net.Http.HttpClient 发出帖子请求，我的代码如下所示

public async Task<LoginResponse> Login(User user)
{
    HttpClient client = await GetClient();

    var response = await client.PostAsync(Url, new StringContent(JsonConvert.SerializeObject(user), Encoding.UTF8, "application/json"));
    var mobileResult = await response.Content.ReadAsStringAsync();
    var result = JsonConvert.DeserializeObject<LoginResponse>(mobileResult);

    return result;
}

当我提出请求时，我收到此错误

System.Net.Http.HttpRequestException：发送时出错 请求。 ---> System.Runtime.InteropServices.COMException： 找不到与此错误代码相关的文本。

证书颁发机构无效或不正确

在 System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务 任务）在 System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务 任务）在 System.Net.Http.HttpHandlerToFilter.d__4.MoveNext() --- 从先前抛出异常的位置结束堆栈跟踪 --- 在 System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务 任务）在 System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务 任务）在 System.Net.Http.HttpClientHandler.d__86.MoveNext() --- 内部异常堆栈跟踪结束 --- 在 System.Net.Http.HttpClientHandler.d__86.MoveNext() --- 从先前抛出异常的位置结束堆栈跟踪 --- 在 System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务 任务）在 System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务 任务）在 System.Net.Http.HttpClient.d__58.MoveNext() --- 从先前抛出异常的位置结束堆栈跟踪 --- 在 System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务 任务）在 System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务 任务）在 System.Runtime.CompilerServices.TaskAwaiter1.GetResult() at SampleApp.Services.LoginService.<Login>d__2.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Runtime.CompilerServices.TaskAwaiter1.GetResult() 在 SampleApp.Views.LoginPage.d__1.MoveNext()

我认为自签名 SSL 会导致问题。我知道我可以使用 Windows.Web HttpClient 来忽略 SSL 错误，但由于一些问题，现在不可能。 我怎么解决这个问题 ？提前致谢。

Answer 1

此代码有助于解决 Xamarin-Windows (UWP) - Windows 8.1 中的以下错误

“找不到与此错误代码相关的文本。”

  public interface IServerCommunication
  {
   Task<string> GetFromServerAsync(string URL);
  }   

//稍后，当我下载数据时：（URL 是提供的字符串）

  string result = await DependencyService.Get<IServerCommunication> 
  ().GetFromServerAsync(URL);

   public async Task<string> GetFromServerAsync(string URL)
   {
    HttpClient client = await PreparedClientAsync();

    HttpResponseMessage response;

    try
    {
    response = await client.GetAsync(new Uri(URL));

    IBuffer buffer = await response.Content.ReadAsBufferAsync();
    DataReader reader = DataReader.FromBuffer(buffer);
    byte[] fileContent = new byte[reader.UnconsumedBufferLength];
    reader.ReadBytes(fileContent);
    string result = Encoding.UTF8.GetString(fileContent, 0, fileContent.Length);

    return result;
    }
    catch (Exception ex)
    {
    return "error";
    }
    }


  private async Task<HttpClient> PreparedClientAsync()
  {
   var filter = new Windows.Web.Http.Filters.HttpBaseProtocolFilter();

   filter.IgnorableServerCertificateErrors.Add(ChainValidationResult.Expired);
   filter.IgnorableServerCertificateErrors.Add(ChainValidationResult.Untrusted);
   filter.IgnorableServerCertificateErrors.Add(ChainValidationResult.InvalidName);

    HttpClient client = new HttpClient(filter);

    //I also handle other stuff here (client certificate, authentification), but the 
    lines above should allow the Httpclient to accept all certificates

    return client;
   }

Answer 2

使用自签名证书的解决方法是在初始化 HttpClient 之前插入以下代码，以忽略 SSL 证书错误：

ServicePointManager.ServerCertificateValidationCallback += (sender, cert, chain, sslPolicyErrors) => true;

确保包含 System.Net。

希望这会有所帮助。