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// Copyright 2015 Brian Smith.
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHORS DISCLAIM ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR
// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
use core::fmt;
use core::ops::ControlFlow;
/// An error that occurs during certificate validation or name validation.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
#[non_exhaustive]
pub enum Error {
/// The encoding of some ASN.1 DER-encoded item is invalid.
BadDer,
/// The encoding of an ASN.1 DER-encoded time is invalid.
BadDerTime,
/// A CA certificate is being used as an end-entity certificate.
CaUsedAsEndEntity,
/// The certificate is expired; i.e. the time it is being validated for is
/// later than the certificate's notAfter time.
CertExpired,
/// The certificate is not valid for the name it is being validated for.
CertNotValidForName,
/// The certificate is not valid yet; i.e. the time it is being validated
/// for is earlier than the certificate's notBefore time.
CertNotValidYet,
/// The certificate, or one of its issuers, has been revoked.
CertRevoked,
/// An end-entity certificate is being used as a CA certificate.
EndEntityUsedAsCa,
/// An X.509 extension is invalid.
ExtensionValueInvalid,
/// The certificate validity period (notBefore, notAfter) is invalid; e.g.
/// the notAfter time is earlier than the notBefore time.
InvalidCertValidity,
/// A CRL number extension was invalid:
/// - it was mis-encoded
/// - it was negative
/// - it was too long
InvalidCrlNumber,
/// A iPAddress name constraint was invalid:
/// - it had a sparse network mask (ie, cannot be written in CIDR form).
/// - it was too long or short
InvalidNetworkMaskConstraint,
/// A serial number was invalid:
/// - it was misencoded
/// - it was negative
/// - it was too long
InvalidSerialNumber,
/// The CRL signature is invalid for the issuer's public key.
InvalidCrlSignatureForPublicKey,
/// The signature is invalid for the given public key.
InvalidSignatureForPublicKey,
/// A CRL was signed by an issuer that has a KeyUsage bitstring that does not include
/// the cRLSign key usage bit.
IssuerNotCrlSigner,
/// A presented or reference DNS identifier was malformed, potentially
/// containing invalid characters or invalid labels.
MalformedDnsIdentifier,
/// The certificate extensions are malformed.
///
/// In particular, webpki requires the DNS name(s) be in the subjectAltName
/// extension as required by the CA/Browser Forum Baseline Requirements
/// and as recommended by RFC6125.
MalformedExtensions,
/// A name constraint was malformed, potentially containing invalid characters or
/// invalid labels.
MalformedNameConstraint,
/// The maximum number of name constraint comparisons has been reached.
MaximumNameConstraintComparisonsExceeded,
/// The maximum number of internal path building calls has been reached. Path complexity is too great.
MaximumPathBuildCallsExceeded,
/// The path search was terminated because it became too deep.
MaximumPathDepthExceeded,
/// The maximum number of signature checks has been reached. Path complexity is too great.
MaximumSignatureChecksExceeded,
/// The certificate violates one or more name constraints.
NameConstraintViolation,
/// The certificate violates one or more path length constraints.
PathLenConstraintViolated,
/// The certificate is not valid for the Extended Key Usage for which it is
/// being validated.
RequiredEkuNotFound,
/// The algorithm in the TBSCertificate "signature" field of a certificate
/// does not match the algorithm in the signature of the certificate.
SignatureAlgorithmMismatch,
/// A valid issuer for the certificate could not be found.
UnknownIssuer,
/// The certificate is not a v3 X.509 certificate.
///
/// This error may be also reported if the certificate version field
/// is malformed.
UnsupportedCertVersion,
/// The certificate contains an unsupported critical extension.
UnsupportedCriticalExtension,
/// The CRL is not a v2 X.509 CRL.
///
/// The RFC 5280 web PKI profile mandates only version 2 be used. See section
/// 5.1.2.1 for more information.
///
/// This error may also be reported if the CRL version field is malformed.
UnsupportedCrlVersion,
/// The CRL is an unsupported "delta" CRL.
UnsupportedDeltaCrl,
/// The CRL contains unsupported "indirect" entries.
UnsupportedIndirectCrl,
/// The revocation reason is not in the set of supported revocation reasons.
UnsupportedRevocationReason,
/// The signature algorithm for a signature over a CRL is not in the set of supported
/// signature algorithms given.
UnsupportedCrlSignatureAlgorithm,
/// The signature algorithm for a signature is not in the set of supported
/// signature algorithms given.
UnsupportedSignatureAlgorithm,
/// The CRL signature's algorithm does not match the algorithm of the issuer
/// public key it is being validated for. This may be because the public key
/// algorithm's OID isn't recognized (e.g. DSA), or the public key
/// algorithm's parameters don't match the supported parameters for that
/// algorithm (e.g. ECC keys for unsupported curves), or the public key
/// algorithm and the signature algorithm simply don't match (e.g.
/// verifying an RSA signature with an ECC public key).
UnsupportedCrlSignatureAlgorithmForPublicKey,
/// The signature's algorithm does not match the algorithm of the public
/// key it is being validated for. This may be because the public key
/// algorithm's OID isn't recognized (e.g. DSA), or the public key
/// algorithm's parameters don't match the supported parameters for that
/// algorithm (e.g. ECC keys for unsupported curves), or the public key
/// algorithm and the signature algorithm simply don't match (e.g.
/// verifying an RSA signature with an ECC public key).
UnsupportedSignatureAlgorithmForPublicKey,
}
impl Error {
// Compare the Error with the new error by rank, returning the higher rank of the two as
// the most specific error.
pub(crate) fn most_specific(self, new: Error) -> Error {
// Assign an error a numeric value ranking it by specificity.
if self.rank() >= new.rank() {
self
} else {
new
}
}
// Return a numeric indication of how specific the error is, where an error with a higher rank
// is considered more useful to an end user than an error with a lower rank. This is used by
// Error::most_specific to compare two errors in order to return which is more specific.
#[allow(clippy::as_conversions)] // We won't exceed u32 errors.
pub(crate) fn rank(&self) -> u32 {
match &self {
// Errors related to certificate validity
Error::CertNotValidYet | Error::CertExpired => 290,
Error::CertNotValidForName => 280,
Error::CertRevoked => 270,
Error::InvalidCrlSignatureForPublicKey | Error::InvalidSignatureForPublicKey => 260,
Error::SignatureAlgorithmMismatch => 250,
Error::RequiredEkuNotFound => 240,
Error::NameConstraintViolation => 230,
Error::PathLenConstraintViolated => 220,
Error::CaUsedAsEndEntity | Error::EndEntityUsedAsCa => 210,
Error::IssuerNotCrlSigner => 200,
// Errors related to supported features used in an invalid way.
Error::InvalidCertValidity => 190,
Error::InvalidNetworkMaskConstraint => 180,
Error::InvalidSerialNumber => 170,
Error::InvalidCrlNumber => 160,
// Errors related to unsupported features.
Error::UnsupportedCrlSignatureAlgorithmForPublicKey
| Error::UnsupportedSignatureAlgorithmForPublicKey => 150,
Error::UnsupportedCrlSignatureAlgorithm | Error::UnsupportedSignatureAlgorithm => 140,
Error::UnsupportedCriticalExtension => 130,
Error::UnsupportedCertVersion => 130,
Error::UnsupportedCrlVersion => 120,
Error::UnsupportedDeltaCrl => 110,
Error::UnsupportedIndirectCrl => 100,
Error::UnsupportedRevocationReason => 90,
// Reserved for webpki 0.102.0+ usages:
// Error::UnsupportedRevocationReasonsPartitioning => 80,
// Error::UnsupportedCrlIssuingDistributionPoint => 70,
Error::MaximumPathDepthExceeded => 61,
// Errors related to malformed data.
Error::MalformedDnsIdentifier => 60,
Error::MalformedNameConstraint => 50,
Error::MalformedExtensions => 40,
Error::ExtensionValueInvalid => 30,
// Generic DER errors.
Error::BadDerTime => 20,
Error::BadDer => 10,
// Special case errors - not subject to ranking.
Error::MaximumSignatureChecksExceeded => 0,
Error::MaximumPathBuildCallsExceeded => 0,
Error::MaximumNameConstraintComparisonsExceeded => 0,
// Default catch all error - should be renamed in the future.
Error::UnknownIssuer => 0,
}
}
/// Returns true for errors that should be considered fatal during path building. Errors of
/// this class should halt any further path building and be returned immediately.
#[inline]
pub(crate) fn is_fatal(&self) -> bool {
matches!(
self,
Error::MaximumSignatureChecksExceeded
| Error::MaximumPathBuildCallsExceeded
| Error::MaximumNameConstraintComparisonsExceeded
)
}
}
impl From<Error> for ControlFlow<Error, Error> {
fn from(value: Error) -> Self {
match value {
// If an error is fatal, we've exhausted the potential for continued search.
err if err.is_fatal() => Self::Break(err),
// Otherwise we've rejected one candidate chain, but may continue to search for others.
err => Self::Continue(err),
}
}
}
impl fmt::Display for Error {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "{:?}", self)
}
}
#[cfg(feature = "std")]
#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
impl ::std::error::Error for Error {}
impl From<untrusted::EndOfInput> for Error {
fn from(_: untrusted::EndOfInput) -> Self {
Error::BadDer
}
}