Add support for parsing certificate formats other than raw, DER-encoded cert...

net/base/pem_tokenizer.h

+// Copyright (c) 2010 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_BASE_PEM_TOKENIZER_H_
+#define NET_BASE_PEM_TOKENIZER_H_
+
+#include <string>
+#include <vector>
+
+#include "base/string_piece.h"
+
+namespace net {
+
+// PEMTokenizer is a utility class for the parsing of data encapsulated
+// using RFC 1421, Privacy Enhancement for Internet Electronic Mail. It
+// does not implement the full specification, most notably it does not
+// support the Encapsulated Header Portion described in Section 4.4.
+class PEMTokenizer {
+ public:
+  // Create a new PEMTokenizer that iterates through |str| searching for
+  // instances of PEM encoded blocks that are of the |allowed_block_types|.
+  // |str| must remain valid for the duration of the PEMTokenizer.
+  PEMTokenizer(const base::StringPiece& str,
+               const std::vector<std::string>& allowed_block_types);
+
+  // Attempts to decode the next PEM block in the string. Returns false if no
+  // PEM blocks can be decoded. The decoded PEM block will be available via
+  // data().
+  bool GetNext();
+
+  // Returns the PEM block type (eg: CERTIFICATE) of the last successfully
+  // decoded PEM block.
+  // GetNext() must have returned true before calling this method.
+  const std::string& block_type() const { return block_type_; }
+
+  // Returns the raw, Base64-decoded data of the last successfully decoded
+  // PEM block.
+  // GetNext() must have returned true before calling this method.
+  const std::string& data() const { return data_; }
+
+ private:
+  void Init(const base::StringPiece& str,
+            const std::vector<std::string>& allowed_block_types);
+
+  // A simple cache of the allowed PEM header and footer for a given PEM
+  // block type, so that it is only computed once.
+  struct PEMType {
+    std::string type;
+    std::string header;
+    std::string footer;
+  };
+
+  // The string to search, which must remain valid for as long as this class
+  // is around.
+  base::StringPiece str_;
+
+  // The current position within |str_| that searching should begin from,
+  // or StringPiece::npos if iteration is complete
+  base::StringPiece::size_type pos_;
+
+  // The type of data that was encoded, as indicated in the PEM
+  // Pre-Encapsulation Boundary (eg: CERTIFICATE, PKCS7, or
+  // PRIVACY-ENHANCED MESSAGE).
+  std::string block_type_;
+
+  // The types of PEM blocks that are allowed. PEM blocks that are not of
+  // one of these types will be skipped.
+  std::vector<PEMType> block_types_;
+
+  // The raw (Base64-decoded) data of the last successfully decoded block.
+  std::string data_;
+
+  DISALLOW_COPY_AND_ASSIGN(PEMTokenizer);
+};
+
+}  // namespace net
+
+#endif  // NET_BASE_PEM_TOKENIZER_H_