RemoteCertificateValidationCallback Delegar

Definição

Namespace:

System.Net.Security

Assembly:

System.Net.Security.dll

Assembly:

System.dll

Assembly:

netstandard.dll

Verifica o certificado SSL (protocolo SSL) remoto usado para autenticação.

public delegate bool RemoteCertificateValidationCallback(System::Object ^ sender, X509Certificate ^ certificate, X509Chain ^ chain, SslPolicyErrors sslPolicyErrors);

public delegate bool RemoteCertificateValidationCallback(object sender, X509Certificate? certificate, X509Chain? chain, SslPolicyErrors sslPolicyErrors);

public delegate bool RemoteCertificateValidationCallback(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors);

type RemoteCertificateValidationCallback = delegate of obj * X509Certificate * X509Chain * SslPolicyErrors -> bool

Public Delegate Function RemoteCertificateValidationCallback(sender As Object, certificate As X509Certificate, chain As X509Chain, sslPolicyErrors As SslPolicyErrors) As Boolean 

Parâmetros

sender

Object

Um objeto que contém informações de estado para essa validação.

certificate

X509Certificate

O certificado usado para autenticar a entidade remota.

chain

X509Chain

A cadeia de autoridades de certificação associada ao certificado remoto.

sslPolicyErrors

SslPolicyErrors

Um ou mais erros associados ao certificado remoto.

Valor Retornado

Boolean

Um valor de Boolean que determina se o certificado especificado é aceito para autenticação.

Exemplos

O exemplo de código a seguir implementa um método que é invocado por uma instância da RemoteCertificateValidationCallback classe. Se houver erros de validação, esse método os exibirá e retornará false, o que impede a comunicação com o servidor não autenticado.

    // Load a table of errors that might cause 
    // the certificate authentication to fail.
    static void InitializeCertificateErrors()
    {
        certificateErrors->Add(0x800B0101,
            "The certification has expired.");
        certificateErrors->Add(0x800B0104,
            "A path length constraint "
            "in the certification chain has been violated.");
        certificateErrors->Add(0x800B0105,
            "A certificate contains an unknown extension "
            "that is marked critical.");
        certificateErrors->Add(0x800B0107,
            "A parent of a given certificate in fact "
            "did not issue that child certificate.");
        certificateErrors->Add(0x800B0108,
            "A certificate is missing or has an empty value "
            "for a necessary field.");
        certificateErrors->Add(0x800B0109,
            "The certificate root is not trusted.");
        certificateErrors->Add(0x800B010C,
            "The certificate has been revoked.");
        certificateErrors->Add(0x800B010F,
            "The name in the certificate does not not match "
            "the host name requested by the client.");
        certificateErrors->Add(0x800B0111,
            "The certificate was explicitly marked "
            "as untrusted by the user.");
        certificateErrors->Add(0x800B0112,
            "A certification chain processed correctly, "
            "but one of the CA certificates is not trusted.");
        certificateErrors->Add(0x800B0113,
            "The certificate has an invalid policy.");
        certificateErrors->Add(0x800B0114,
            "The certificate name is either not "
            "in the permitted list or is explicitly excluded.");
        certificateErrors->Add(0x80092012,
            "The revocation function was unable to check "
            "revocation for the certificate.");
        certificateErrors->Add(0x80090327,
            "An unknown error occurred while "
            "processing the certificate.");
        certificateErrors->Add(0x80096001,
            "A system-level error occurred "
            "while verifying trust.");
        certificateErrors->Add(0x80096002,
            "The certificate for the signer of the message "
            "is invalid or not found.");
        certificateErrors->Add(0x80096003,
            "One of the counter signatures was invalid.");
        certificateErrors->Add(0x80096004,
            "The signature of the certificate "
            "cannot be verified.");
        certificateErrors->Add(0x80096005,
            "The time stamp signature or certificate "
            "could not be verified or is malformed.");
        certificateErrors->Add(0x80096010,
            "The digital signature of the object "
            "was not verified.");
        certificateErrors->Add(0x80096019,
            "The basic constraint extension of a certificate "
            "has not been observed.");
    }

    static String^ CertificateErrorDescription(UInt32 problem)
    {
        // Initialize the error message dictionary 
        // if it is not yet available.
        if (certificateErrors->Count == 0)
        {
            InitializeCertificateErrors();
        }

        String^ description = safe_cast<String^>(
            certificateErrors[problem]);
        if (description == nullptr)
        {
            description = String::Format(
                CultureInfo::CurrentCulture,
                "Unknown certificate error - 0x{0:x8}",
                problem);
        }

        return description;
    }

public:
    // The following method is invoked 
    // by the CertificateValidationDelegate.
static bool ValidateServerCertificate(
        Object^ sender,
        X509Certificate^ certificate,
        X509Chain^ chain,
        SslPolicyErrors sslPolicyErrors)
    {
    
        Console::WriteLine("Validating the server certificate.");
        if (sslPolicyErrors == SslPolicyErrors::None)
            return true;

        Console::WriteLine("Certificate error: {0}", sslPolicyErrors);

        // Do not allow this client to communicate with unauthenticated servers.
        return false;
    }

// The following method is invoked by the RemoteCertificateValidationDelegate.
public static bool ValidateServerCertificate(
      object sender,
      X509Certificate certificate,
      X509Chain chain,
      SslPolicyErrors sslPolicyErrors)
{
   if (sslPolicyErrors == SslPolicyErrors.None)
        return true;

    Console.WriteLine("Certificate error: {0}", sslPolicyErrors);

    // Do not allow this client to communicate with unauthenticated servers.
    return false;
}

O exemplo de código a seguir cria o delegado usando o método definido no exemplo de código anterior.

// Create a TCP/IP client socket.
// machineName is the host running the server application.
TcpClient^ client = gcnew TcpClient(machineName, 8080);
Console::WriteLine("Client connected.");
  
// Create an SSL stream that will close 
// the client's stream.
SslStream^ sslStream = gcnew SslStream(
    client->GetStream(), false,
    gcnew RemoteCertificateValidationCallback(ValidateServerCertificate),
    nullptr);
  
// The server name must match the name
// on the server certificate.
try
{
    sslStream->AuthenticateAsClient(serverName);
}
catch (AuthenticationException^ ex) 
{
    Console::WriteLine("Exception: {0}", ex->Message);
    if (ex->InnerException != nullptr)
    {
        Console::WriteLine("Inner exception: {0}", 
            ex->InnerException->Message);
    }

    Console::WriteLine("Authentication failed - "
        "closing the connection.");
    sslStream->Close();
    client->Close();
    return;
}

// Create a TCP/IP client socket.
// machineName is the host running the server application.
TcpClient client = new TcpClient(machineName,443);
Console.WriteLine("Client connected.");
// Create an SSL stream that will close the client's stream.
SslStream sslStream = new SslStream(
    client.GetStream(),
    false,
    new RemoteCertificateValidationCallback (ValidateServerCertificate),
    null
    );
// The server name must match the name on the server certificate.
try
{
    sslStream.AuthenticateAsClient(serverName);
}
catch (AuthenticationException e)
{
    Console.WriteLine("Exception: {0}", e.Message);
    if (e.InnerException != null)
    {
        Console.WriteLine("Inner exception: {0}", e.InnerException.Message);
    }
    Console.WriteLine ("Authentication failed - closing the connection.");
    client.Close();
    return;
}

Comentários

O argumento do sslPolicyErrors delegado contém quaisquer erros de certificado retornados pela SSPI durante a autenticação do cliente ou servidor. O Boolean valor retornado pelo método invocado por esse delegado determina se a autenticação tem permissão para ter êxito.

Esse delegado é usado com a SslStream classe.

Métodos de Extensão

GetMethodInfo(Delegate)

Obtém um objeto que representa o método representado pelo delegado especificado.

Confira também

• LocalCertificateSelectionCallback