使用 HTTP Client 请求 HTTPS 的 API 时出现 The certificate cannot be verified up to a trusted certification authority 异常，并且证书已经传入。
下面就是问题代码：
public class Program { public static void Main(string[] args) { var url = @"https://xxx.xxx.xxx.xxx:xxxx/xxx-web/services/xxxx?wsdl"; var handler = new HttpClientHandler { ClientCertificateOptions = ClientCertificateOption.Manual, ClientCertificates = { new X509Certificate2(@"E:\cert\rootTrust.cer","11111111"), new X509Certificate2(@"E:\cert\middleTrust.cer","11111111"), new X509Certificate2(@"E:\cert\wskey.pfx","ws654321") } }; var webRequest = new HttpClient(handler); var result = webRequest.GetStringAsync(url).GetAwaiter().GetResult(); Console.WriteLine(result); } }
原因
因为在发出 HTTPS 请求的时候，HttpClient 都会检查 SSL 证书是否合法。如果不合法的话，就会导致抛出异常信息，而对方给出的证书是自签发的测试接口的证书，所以不是一个合法的 SSL 证书。
解决
在 HttpClientHandler 当中会有一个 ServerCertificateCustomValidationCallback 事件，该事件用于判定证书验证是否通过。我们可以挂接该事件，然后逻辑编写为直接返回 true 结果，这样就会忽略掉证书异常的情况。
最新的代码如下：
public class Program { public static void Main(string[] args) { var url = @"https://xxx.xxx.xxx.xxx:xxxx/xxx-web/services/xxxx?wsdl"; var handler = new HttpClientHandler { ServerCertificateCustomValidationCallback = (message, certificate2, arg3, arg4) => true, ClientCertificateOptions = ClientCertificateOption.Manual, ClientCertificates = { new X509Certificate2(@"E:\cert\rootTrust.cer","11111111"), new X509Certificate2(@"E:\cert\middleTrust.cer","11111111"), new X509Certificate2(@"E:\cert\wskey.pfx","ws654321") } }; var webRequest = new HttpClient(handler); var result = webRequest.GetStringAsync(url).GetAwaiter().GetResult(); Console.WriteLine("xx"); } }