Class for parsing and evaluating RFC 5280 NameConstraints.

net/cert/internal/name_constraints.h

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef NET_CERT_INTERNAL_NAME_CONSTRAINTS_H_
+#define NET_CERT_INTERNAL_NAME_CONSTRAINTS_H_
+
+#include <vector>
+
+#include "net/base/ip_address_number.h"
+#include "net/der/input.h"
+
+namespace net {
+
+// Parses a NameConstraints extension value and allows testing whether names are
+// allowed under those constraints as defined by RFC 5280 section 4.2.1.10.
+class NET_EXPORT NameConstraints {
+ public:
+  // TODO: make this private? (requires making some currently anonymous
+  // functions into private static methods.) Or maybe this will need to be split
+  // out into a public class, since GeneralNames is used other places in a
+  // certificate also...
+  struct GeneralNames {
+    GeneralNames();
+    ~GeneralNames();
+
+    // ASCII hostnames.
+    std::vector<std::string> dns_names;
+
+    // DER encoded Name values (not including the Sequence tag).
+    std::vector<std::vector<uint8_t>> directory_names;
+
+    // iPAddresses. For Subject Alternative Name this will be 4 bytes for IPv4
+    // or 16 bytes for IPv6. For Name Constraints, it will be ip + netmask
+    // (8 bytes for IPv4, 32 bytes for IPv6).
+    std::vector<std::vector<uint8_t>> ip_addresses;
+
+    // Whether any values of the other types were present.
+    bool has_other_names;
+    bool has_rfc822_names;
+    bool has_x400_addresses;
+    bool has_edi_party_names;
+    bool has_uniform_resource_identifiers;
+    bool has_registered_ids;
+  };
+
+  ~NameConstraints();
+
+  // Parse a DER-encoded NameConstraints extension. |extension_value| should be
+  // the extnValue octet string from the extension, |is_critical| should be true
+  // if the extension was marked critical.
+  // Returns true if the extension was parsed successfully.
+  // The object lifetime is not bound to the lifetime of |extension_value| data.
+  bool Parse(const der::Input& extension_value, bool is_critical);
+
+  // Tests if a certificate is allowed by the name constraints.
+  // |subject_rdn_sequence| should be the DER-encoded value of the subject's
+  // RDNSequence field (not including Sequence tag), and may be an empty ASN.1
+  // sequence.  |subject_alt_name| should be the extnValue of the subjectAltName
+  // extension, or empty if the cert did not have a subjectAltName extension.
+  // |is_leaf_cert| should be true if the certificate is the leaf of the
+  // certificate chain, in which case subject commonName hostname/ip checking is
+  // done.
+  bool IsPermittedCert(const der::Input& subject_rdn_sequence,
+                       const der::Input& subject_alt_name,
+                       bool is_leaf_cert) const;
+
+  // Returns true if the ASCII hostname |name| is permitted.
+  // |name| may be a wildcard hostname (starts with "*."). Eg, "*.bar.com" is
+  // considered would not be permitted if "bar.com" is permitted and
+  // "foo.bar.com" is excluded, while "*.baz.com" would only be permitted if
+  // "baz.com" is permitted.
+  bool IsPermittedDNSName(const std::string& name) const;
+
+  // Returns true if the directoryName |name| is permitted.
+  // |name_rdn_sequence| should be the DER-encoded RDNSequence value (not
+  // including the Sequence tag.)
+  bool IsPermittedDirectoryName(const der::Input& name_rdn_sequence) const;
+
+  // Returns true if the iPAddress |ip| is permitted.
+  bool IsPermittedIP(const IPAddressNumber& ip) const;
+
+  // These name types aren't supported, therefore names of these types are
+  // permitted only if they don't appear in the name constraints at all, or if
+  // the name constraint they appeared in was non-critical.
+  //
+  // RFC 5280 section 4.2.1.10 says:
+  // Applications conforming to this profile MUST be able to process name
+  // constraints that are imposed on the directoryName name form and SHOULD be
+  // able to process name constraints that are imposed on the rfc822Name,
+  // uniformResourceIdentifier, dNSName, and iPAddress name forms.
+  // If a name constraints extension that is marked as critical
+  // imposes constraints on a particular name form, and an instance of
+  // that name form appears in the subject field or subjectAltName
+  // extension of a subsequent certificate, then the application MUST
+  // either process the constraint or reject the certificate.
+  bool IsPermittedOtherName() const;
+  bool IsPermittedRFC822Name() const;
+  bool IsPermittedX400Address() const;
+  bool IsPermittedEdiPartyName() const;
+  bool IsPermittedURI() const;
+  bool IsPermittedRegisteredId() const;
+
+ private:
+  GeneralNames permitted_subtrees_;
+  GeneralNames excluded_subtrees_;
+};
+
+}  // namespace net
+
+#endif  // NET_CERT_INTERNAL_NAME_CONSTRAINTS_H_