/// <summary>
/// Searches for a certificate extension.
/// </summary>
/// <param name="oid">The extension to search for.</param>
/// <returns>An instance of the <see cref="Extension"/> class -or- a null reference (<b>Nothing</b> in Visual Basic) if the specified extension could not be found.</returns>
/// <exception cref="ArgumentNullException"><paramref name="oid"/> is a null reference (<b>Nothing</b> in Visual Basic).</exception>
public Extension FindExtension(string oid)
{
if (oid == null)
throw new ArgumentNullException();
IntPtr ret = SspiProvider.CertFindExtension(oid, m_CertInfo.cExtension.ToInt32(), m_CertInfo.rgExtension);
if (ret == IntPtr.Zero) {
return null;
} else {
CERT_EXTENSION ce = (CERT_EXTENSION)Marshal.PtrToStructure(ret, typeof(CERT_EXTENSION));
Extension ext = new Extension(Marshal.PtrToStringAnsi(ce.pszObjId), ce.fCritical != 0, new byte[ce.ValuecbData]);
Marshal.Copy(ce.ValuepbData, ext.EncodedValue, 0, ce.ValuecbData);
return ext;
}
}
/// <summary>
/// Decodes the specified extension and returns an object of the specified type that is instantiated with the decoded bytes.
/// </summary>
/// <param name="extension">The certificate extension to decode.</param>
/// <param name="oid">The Object Identifier of the structure. Refer to the documentation of the <a href="http://msdn.microsoft.com/library/en-us/security/security/cryptdecodeobject.asp">CryptDecodeObject</a> function for more information.</param>
/// <param name="returnType">A <see cref="Type"/> instance. See remarks.</param>
/// <returns>An object of the type <paramref name="returnType"/>.</returns>
/// <remarks><p>
/// The specified type should have a public constructor that takes an IntPtr and an int as parameters [in that order].
/// The IntPtr is a pointer to the decoded buffer and the int contains the number of decoded bytes.
/// The type should not keep the IntPtr reference after construction of an instance, because the memory is freed when the DecodeExtension method returns.
/// </p></remarks>
/// <exception cref="ArgumentNullException">One of the parameters is a null reference (<b>Nothing</b> in Visual Basic).</exception>
/// <exception cref="CertificateException">An error occurs while decoding the certificate extension.</exception>
public static object DecodeExtension(Extension extension, string oid, Type returnType)
{
if (oid == null)
throw new ArgumentNullException("oid");
IntPtr buffer = Marshal.StringToHGlobalAnsi(oid);
try {
return DecodeExtension(extension, buffer, returnType);
} finally {
Marshal.FreeHGlobal(buffer);
}
}
/// <summary>
/// Decodes the specified extension and returns an object of the specified type that is instantiated with the decoded bytes.
/// </summary>
/// <param name="extension">The certificate extension to decode.</param>
/// <param name="oid">The Object Identifier of the structure.</param>
/// <param name="returnType">A <see cref="Type"/> instance. See remarks.</param>
/// <returns>An object of the type <paramref name="returnType"/>.</returns>
/// <remarks><p>
/// The specified type should have a public constructor that takes an IntPtr and an int as parameters [in that order].
/// The IntPtr is a pointer to the decoded buffer and the int contains the number of decoded bytes.
/// The type should not keep the IntPtr reference after construction of an instance, because the memory is freed when the DecodeExtension method returns.
/// </p></remarks>
/// <exception cref="ArgumentNullException">One of the parameters is a null reference (<b>Nothing</b> in Visual Basic).</exception>
/// <exception cref="CertificateException">An error occurs while decoding the certificate extension.</exception>
protected static object DecodeExtension(Extension extension, IntPtr oid, Type returnType)
{
if (extension.EncodedValue == null || returnType == null)
throw new ArgumentNullException();
int size = 0;
if (SspiProvider.CryptDecodeObject(SecurityConstants.PKCS_7_ASN_ENCODING | SecurityConstants.X509_ASN_ENCODING, oid, extension.EncodedValue, extension.EncodedValue.Length, 0, IntPtr.Zero, ref size) == 0)
throw new CertificateException("Could not decode the extension.");
IntPtr buffer = Marshal.AllocHGlobal(size);
try {
if (SspiProvider.CryptDecodeObject(SecurityConstants.PKCS_7_ASN_ENCODING | SecurityConstants.X509_ASN_ENCODING, oid, extension.EncodedValue, extension.EncodedValue.Length, 0, buffer, ref size) == 0)
throw new CertificateException("Could not decode the extension.");
return Activator.CreateInstance(returnType, new object[] { buffer, size });
} catch (CertificateException ce) {
throw ce;
} catch (Exception e) {
throw new CertificateException("Unable to instantiate the specified object type.", e);
} finally {
Marshal.FreeHGlobal(buffer);
}
}
/// <summary>
/// Decodes the specified extension and returns an object of the specified type that is instantiated with the decoded bytes.
/// </summary>
/// <param name="extension">The certificate extension to decode.</param>
/// <param name="oid">One of the predefined constants specified in the Win32 CryptoAPI. Refer to the documentation of the <a href="http://msdn.microsoft.com/library/en-us/security/security/cryptdecodeobject.asp">CryptDecodeObject</a> function for more information.</param>
/// <param name="returnType">A <see cref="Type"/> instance. See remarks.</param>
/// <returns>An object of the type <paramref name="returnType"/>.</returns>
/// <remarks><p>
/// The specified type should have a public constructor that takes an IntPtr and an int as parameters [in that order].
/// The IntPtr is a pointer to the decoded buffer and the int contains the number of decoded bytes.
/// The type should not keep the IntPtr reference after construction of an instance, because the memory is freed when the DecodeExtension method returns.
/// </p></remarks>
/// <exception cref="ArgumentNullException">One of the parameters is a null reference (<b>Nothing</b> in Visual Basic).</exception>
/// <exception cref="CertificateException">An error occurs while decoding the certificate extension.</exception>
public static object DecodeExtension(Extension extension, int oid, Type returnType)
{
return DecodeExtension(extension, new IntPtr(oid), returnType);
}
/// <summary>
/// Returns a list of extensions of the X.509v3 certificate.
/// </summary>
/// <returns>An array of Extension instances.</returns>
public Extension[] GetExtensions()
{
int len = m_CertInfo.cExtension.ToInt32();
Extension[] ret = new Extension[len];
int extSize = 8 + IntPtr.Size * 2;
IntPtr ptr = m_CertInfo.rgExtension;
Type cest = typeof(CERT_EXTENSION);
CERT_EXTENSION ce;
for (int i = 0; i < len; i++) {
ce = (CERT_EXTENSION)Marshal.PtrToStructure(ptr, cest);
ret[i] = new Extension(Marshal.PtrToStringAnsi(ce.pszObjId), ce.fCritical != 0, new byte[ce.ValuecbData]);
Marshal.Copy(ce.ValuepbData, ret[i].EncodedValue, 0, ce.ValuecbData);
ptr = new IntPtr(ptr.ToInt64() + extSize);
}
return ret;
}
