net/cert/pem_tokenizer.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_CERT_PEM_TOKENIZER_H_
   6 #define NET_CERT_PEM_TOKENIZER_H_
   7
   8 #include <string>
   9 #include <vector>
  10
  11 #include "base/strings/string_piece.h"
  12 #include "net/base/net_export.h"
  13
  14 namespace net {
  15
  16 // PEMTokenizer is a utility class for the parsing of data encapsulated
  17 // using RFC 1421, Privacy Enhancement for Internet Electronic Mail. It
  18 // does not implement the full specification, most notably it does not
  19 // support the Encapsulated Header Portion described in Section 4.4.
  20 class NET_EXPORT_PRIVATE PEMTokenizer {
  21  public:
  22   // Create a new PEMTokenizer that iterates through |str| searching for
  23   // instances of PEM encoded blocks that are of the |allowed_block_types|.
  24   // |str| must remain valid for the duration of the PEMTokenizer.
  25   PEMTokenizer(const base::StringPiece& str,
  26                const std::vector<std::string>& allowed_block_types);
  27   ~PEMTokenizer();
  28
  29   // Attempts to decode the next PEM block in the string. Returns false if no
  30   // PEM blocks can be decoded. The decoded PEM block will be available via
  31   // data().
  32   bool GetNext();
  33
  34   // Returns the PEM block type (eg: CERTIFICATE) of the last successfully
  35   // decoded PEM block.
  36   // GetNext() must have returned true before calling this method.
  37   const std::string& block_type() const { return block_type_; }
  38
  39   // Returns the raw, Base64-decoded data of the last successfully decoded
  40   // PEM block.
  41   // GetNext() must have returned true before calling this method.
  42   const std::string& data() const { return data_; }
  43
  44  private:
  45   void Init(const base::StringPiece& str,
  46             const std::vector<std::string>& allowed_block_types);
  47
  48   // A simple cache of the allowed PEM header and footer for a given PEM
  49   // block type, so that it is only computed once.
  50   struct PEMType;
  51
  52   // The string to search, which must remain valid for as long as this class
  53   // is around.
  54   base::StringPiece str_;
  55
  56   // The current position within |str_| that searching should begin from,
  57   // or StringPiece::npos if iteration is complete
  58   base::StringPiece::size_type pos_;
  59
  60   // The type of data that was encoded, as indicated in the PEM
  61   // Pre-Encapsulation Boundary (eg: CERTIFICATE, PKCS7, or
  62   // PRIVACY-ENHANCED MESSAGE).
  63   std::string block_type_;
  64
  65   // The types of PEM blocks that are allowed. PEM blocks that are not of
  66   // one of these types will be skipped.
  67   std::vector<PEMType> block_types_;
  68
  69   // The raw (Base64-decoded) data of the last successfully decoded block.
  70   std::string data_;
  71
  72   DISALLOW_COPY_AND_ASSIGN(PEMTokenizer);
  73 };
  74
  75 }  // namespace net
  76
  77 #endif  // NET_CERT_PEM_TOKENIZER_H_