HttpClientHandler.ServerCertificateCustomValidationCallback Property

public:
 property Func<System::Net::Http::HttpRequestMessage ^, System::Security::Cryptography::X509Certificates::X509Certificate2 ^, System::Security::Cryptography::X509Certificates::X509Chain ^, System::Net::Security::SslPolicyErrors, bool> ^ ServerCertificateCustomValidationCallback { Func<System::Net::Http::HttpRequestMessage ^, System::Security::Cryptography::X509Certificates::X509Certificate2 ^, System::Security::Cryptography::X509Certificates::X509Chain ^, System::Net::Security::SslPolicyErrors, bool> ^ get(); void set(Func<System::Net::Http::HttpRequestMessage ^, System::Security::Cryptography::X509Certificates::X509Certificate2 ^, System::Security::Cryptography::X509Certificates::X509Chain ^, System::Net::Security::SslPolicyErrors, bool> ^ value); };

[System.Runtime.Versioning.UnsupportedOSPlatform("browser")]
public Func<System.Net.Http.HttpRequestMessage,System.Security.Cryptography.X509Certificates.X509Certificate2?,System.Security.Cryptography.X509Certificates.X509Chain?,System.Net.Security.SslPolicyErrors,bool>? ServerCertificateCustomValidationCallback { get; set; }

public Func<System.Net.Http.HttpRequestMessage,System.Security.Cryptography.X509Certificates.X509Certificate2,System.Security.Cryptography.X509Certificates.X509Chain,System.Net.Security.SslPolicyErrors,bool> ServerCertificateCustomValidationCallback { get; set; }

[<System.Runtime.Versioning.UnsupportedOSPlatform("browser")>]
member this.ServerCertificateCustomValidationCallback : Func<System.Net.Http.HttpRequestMessage, System.Security.Cryptography.X509Certificates.X509Certificate2, System.Security.Cryptography.X509Certificates.X509Chain, System.Net.Security.SslPolicyErrors, bool> with get, set

member this.ServerCertificateCustomValidationCallback : Func<System.Net.Http.HttpRequestMessage, System.Security.Cryptography.X509Certificates.X509Certificate2, System.Security.Cryptography.X509Certificates.X509Chain, System.Net.Security.SslPolicyErrors, bool> with get, set

Public Property ServerCertificateCustomValidationCallback As Func(Of HttpRequestMessage, X509Certificate2, X509Chain, SslPolicyErrors, Boolean)

Property Value

A callback method to validate the server certificate.

Attributes

UnsupportedOSPlatformAttribute

Examples

The following code example displays the server certificate.

static async Task Main()
{
 // Create an HttpClientHandler object and set to use default credentials
 HttpClientHandler handler = new HttpClientHandler();

 // Set custom server validation callback
 handler.ServerCertificateCustomValidationCallback = ServerCertificateCustomValidation;

 // Create an HttpClient object
 HttpClient client = new HttpClient(handler);

 // Call asynchronous network methods in a try/catch block to handle exceptions
 try
 {
 HttpResponseMessage response = await client.GetAsync("https://learn.microsoft.com/");

 response.EnsureSuccessStatusCode();

 string responseBody = await response.Content.ReadAsStringAsync();
 Console.WriteLine($"Read {responseBody.Length} characters");
 }
 catch (HttpRequestException e)
 {
 Console.WriteLine("\nException Caught!");
 Console.WriteLine($"Message: {e.Message} ");
 }

 // Need to call dispose on the HttpClient and HttpClientHandler objects
 // when done using them, so the app doesn't leak resources
 handler.Dispose();
 client.Dispose();
}

private static bool ServerCertificateCustomValidation(HttpRequestMessage requestMessage, X509Certificate2? certificate, X509Chain? chain, SslPolicyErrors sslErrors)
{
 // It is possible to inspect the certificate provided by the server.
 Console.WriteLine($"Requested URI: {requestMessage.RequestUri}");
 Console.WriteLine($"Effective date: {certificate?.GetEffectiveDateString()}");
 Console.WriteLine($"Exp date: {certificate?.GetExpirationDateString()}");
 Console.WriteLine($"Issuer: {certificate?.Issuer}");
 Console.WriteLine($"Subject: {certificate?.Subject}");

 // Based on the custom logic it is possible to decide whether the client considers certificate valid or not
 Console.WriteLine($"Errors: {sslErrors}");
 return sslErrors == SslPolicyErrors.None;
}

Remarks

The ServerCertificateCustomValidationCallback can be used to obtain and validate the server certificate.