net/base/asn1_util.h

   1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef NET_BASE_ASN1_UTIL_H_
   6 #define NET_BASE_ASN1_UTIL_H_
   7 #pragma once
   8
   9 #include <vector>
  10
  11 #include "base/string_piece.h"
  12 #include "net/base/net_export.h"
  13
  14 namespace net {
  15
  16 namespace asn1 {
  17
  18 // These are the DER encodings of the tag byte for ASN.1 objects.
  19 static const unsigned kBOOLEAN = 0x01;
  20 static const unsigned kINTEGER = 0x02;
  21 static const unsigned kOCTETSTRING = 0x04;
  22 static const unsigned kOID = 0x06;
  23 static const unsigned kSEQUENCE = 0x30;
  24
  25 // These are flags that can be ORed with the above tag numbers.
  26 static const unsigned kContextSpecific = 0x80;
  27 static const unsigned kConstructed = 0x20;
  28
  29 // kAny matches any tag value;
  30 static const unsigned kAny = 0x10000;
  31 // kOptional denotes an optional element.
  32 static const unsigned kOptional = 0x20000;
  33
  34 // ParseElement parses a DER encoded ASN1 element from |in|, requiring that
  35 // it have the given |tag_value|. It returns true on success. The following
  36 // limitations are imposed:
  37 //   1) tag numbers > 31 are not permitted.
  38 //   2) lengths > 65535 are not permitted.
  39 // On successful return:
  40 //   |in| is advanced over the element
  41 //   |out| contains the element, including the tag and length bytes.
  42 //   |out_header_len| contains the length of the tag and length bytes in |out|.
  43 //
  44 // If |tag_value & kOptional| is true then *out_header_len can be zero after a
  45 // true return value if the element was not found.
  46 bool ParseElement(base::StringPiece* in,
  47                   unsigned tag_value,
  48                   base::StringPiece* out,
  49                   unsigned *out_header_len);
  50
  51 // GetElement performs the same actions as ParseElement, except that the header
  52 // bytes are not included in the output.
  53 //
  54 // If |tag_value & kOptional| is true then this function cannot distinguish
  55 // between a missing optional element and an empty one.
  56 bool GetElement(base::StringPiece* in,
  57                 unsigned tag_value,
  58                 base::StringPiece* out);
  59
  60 // ExtractSPKIFromDERCert parses the DER encoded certificate in |cert| and
  61 // extracts the bytes of the SubjectPublicKeyInfo. On successful return,
  62 // |spki_out| is set to contain the SPKI, pointing into |cert|.
  63 NET_EXPORT_PRIVATE bool ExtractSPKIFromDERCert(base::StringPiece cert,
  64                                                base::StringPiece* spki_out);
  65
  66 // ExtractCRLURLsFromDERCert parses the DER encoded certificate in |cert| and
  67 // extracts the URL of each CRL. On successful return, the elements of
  68 // |urls_out| point into |cert|.
  69 //
  70 // CRLs that only cover a subset of the reasons are omitted as the spec
  71 // requires that at least one CRL be included that covers all reasons.
  72 //
  73 // CRLs that use an alternative issuer are also omitted.
  74 //
  75 // The nested set of GeneralNames is flattened into a single list because
  76 // having several CRLs with one location is equivalent to having one CRL with
  77 // several locations as far as a CRL filter is concerned.
  78 NET_EXPORT_PRIVATE bool ExtractCRLURLsFromDERCert(
  79     base::StringPiece cert,
  80     std::vector<base::StringPiece>* urls_out);
  81
  82 } // namespace asn1
  83
  84 } // namespace net
  85
  86 #endif // NET_BASE_ASN1_UTIL_H_