public static void AddCrlForCertificate(
X509Certificate2 cert,
SafeX509StoreHandle store,
X509RevocationMode revocationMode,
DateTime verificationTime,
ref TimeSpan remainingDownloadTime)
{
// In Offline mode, accept any cached CRL we have.
// "CRL is Expired" is a better match for Offline than "Could not find CRL"
if (revocationMode != X509RevocationMode.Online)
{
verificationTime = DateTime.MinValue;
}
if (AddCachedCrl(cert, store, verificationTime))
{
return;
}
// Don't do any work if we're over limit or prohibited from fetching new CRLs
if (remainingDownloadTime <= TimeSpan.Zero ||
revocationMode != X509RevocationMode.Online)
{
return;
}
DownloadAndAddCrl(cert, store, ref remainingDownloadTime);
}
private static bool AddCachedCrl(X509Certificate2 cert, SafeX509StoreHandle store, DateTime verificationTime)
{
string crlFile = GetCachedCrlPath(cert);
using (SafeBioHandle bio = Interop.libcrypto.BIO_new_file(crlFile, "rb"))
{
if (bio.IsInvalid)
{
return false;
}
// X509_STORE_add_crl will increase the refcount on the CRL object, so we should still
// dispose our copy.
using (SafeX509CrlHandle crl = Interop.libcrypto.PEM_read_bio_X509_CRL(bio))
{
if (crl.IsInvalid)
{
return false;
}
// If crl.LastUpdate is in the past, downloading a new version isn't really going
// to help, since we can't rewind the Internet. So this is just going to fail, but
// at least it can fail without using the network.
//
// If crl.NextUpdate is in the past, try downloading a newer version.
DateTime nextUpdate = OpenSslX509CertificateReader.ExtractValidityDateTime(
Interop.Crypto.GetX509CrlNextUpdate(crl));
// OpenSSL is going to convert our input time to universal, so we should be in Local or
// Unspecified (local-assumed).
Debug.Assert(
verificationTime.Kind != DateTimeKind.Utc,
"UTC verificationTime should have been normalized to Local");
// In the event that we're to-the-second accurate on the match, OpenSSL will consider this
// to be already expired.
if (nextUpdate <= verificationTime)
{
return false;
}
// TODO (#3063): Check the return value of X509_STORE_add_crl, and throw on any error other
// than X509_R_CERT_ALREADY_IN_HASH_TABLE
Interop.libcrypto.X509_STORE_add_crl(store, crl);
return true;
}
}
}
private static void DownloadAndAddCrl(
X509Certificate2 cert,
SafeX509StoreHandle store,
ref TimeSpan remainingDownloadTime)
{
string url = GetCdpUrl(cert);
if (url == null)
{
return;
}
// X509_STORE_add_crl will increase the refcount on the CRL object, so we should still
// dispose our copy.
using (SafeX509CrlHandle crl = CertificateAssetDownloader.DownloadCrl(url, ref remainingDownloadTime))
{
// null is a valid return (e.g. no remainingDownloadTime)
if (crl != null && !crl.IsInvalid)
{
// TODO (#3063): Check the return value of X509_STORE_add_crl, and throw on any error other
// than X509_R_CERT_ALREADY_IN_HASH_TABLE
Interop.libcrypto.X509_STORE_add_crl(store, crl);
// Saving the CRL to the disk is just a performance optimization for later requests to not
// need to use the network again, so failure to save shouldn't throw an exception or mark
// the chain as invalid.
try
{
string crlFile = GetCachedCrlPath(cert, mkDir: true);
using (SafeBioHandle bio = Interop.libcrypto.BIO_new_file(crlFile, "wb"))
{
if (!bio.IsInvalid)
{
Interop.libcrypto.PEM_write_bio_X509_CRL(bio, crl);
}
}
}
catch (IOException)
{
}
}
}
}
internal static extern bool X509StoreAddCert(SafeX509StoreHandle ctx, SafeX509Handle x);
internal static extern bool X509StoreSetRevocationFlag(SafeX509StoreHandle ctx, X509RevocationFlag revocationFlag);
internal static extern bool X509StoreCtxInit(SafeX509StoreCtxHandle ctx, SafeX509StoreHandle store, SafeX509Handle x509);
internal static extern bool X509StoreAddCrl(SafeX509StoreHandle ctx, SafeX509CrlHandle x);
internal static extern bool X509_STORE_CTX_init(SafeX509StoreCtxHandle ctx, SafeX509StoreHandle store, SafeX509Handle x509, IntPtr zero);
internal static extern bool X509_STORE_add_cert(SafeX509StoreHandle ctx, SafeX509Handle x);
internal static extern bool X509_STORE_set_flags(SafeX509StoreHandle ctx, X509VerifyFlags flags);
internal static extern bool X509_STORE_add_crl(SafeX509StoreHandle ctx, SafeX509CrlHandle x);