Add parsing code for TBSCertificate's "validity" field.

net/cert/internal/parse_certificate.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_PARSE_CERTIFICATE_H_
 #define NET_CERT_INTERNAL_PARSE_CERTIFICATE_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "net/base/net_export.h"
@@ skipping 136 matching lines @@
   // Corresponds with "issuer" from RFC 5280:
   //         issuer               Name,
   //
   // This contains the full (unverified) Tag-Length-Value for a SEQUENCE. No
   // guarantees are made regarding the value of this SEQUENCE.
   der::Input issuer_tlv;
 
   // Corresponds with "validity" from RFC 5280:
   //         validity             Validity,
   //
-  // This contains the full (unverified) Tag-Length-Value for a SEQUENCE. No
-  // guarantees are made regarding the value of this SEQUENCE.
-  der::Input validity_tlv;
+  // Where Validity is defined as:
+  //
+  //   Validity ::= SEQUENCE {
+  //        notBefore      Time,
+  //        notAfter       Time }
+  //
+  // Parsing guarantees that notBefore (validity_not_before) and notAfter
+  // (validity_not_after) are valid DER-encoded dates, however it DOES NOT
+  // gurantee anything about their values. For instance notAfter could be
+  // before notBefore, or the dates could indicate an expired certificate.
+  // Consumers are responsible for testing expiration.
+  der::GeneralizedTime validity_not_before;
+  der::GeneralizedTime validity_not_after;
 
   // Corresponds with "subject" from RFC 5280:
   //         subject              Name,
   //
   // This contains the full (unverified) Tag-Length-Value for a SEQUENCE. No
   // guarantees are made regarding the value of this SEQUENCE.
   der::Input subject_tlv;
 
   // Corresponds with "subjectPublicKeyInfo" from RFC 5280:
   //         subjectPublicKeyInfo SubjectPublicKeyInfo,
@@ skipping 30 matching lines @@
   // EXPLICIT outer tag is stripped.)
   //
   // Parsing guarantees that if extensions is present the version is v3.
   bool has_extensions = false;
   der::Input extensions_tlv;
 };
 
 }  // namespace net
 
 #endif  // NET_CERT_INTERNAL_PARSE_CERTIFICATE_H_