net/quic/crypto/crypto_framer.h

   1 // Copyright (c) 2012 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_QUIC_CRYPTO_CRYPTO_FRAMER_H_
   6 #define NET_QUIC_CRYPTO_CRYPTO_FRAMER_H_
   7
   8 #include <utility>
   9 #include <vector>
  10
  11 #include "base/basictypes.h"
  12 #include "base/logging.h"
  13 #include "base/strings/string_piece.h"
  14 #include "net/base/net_export.h"
  15 #include "net/quic/crypto/crypto_handshake_message.h"
  16 #include "net/quic/quic_protocol.h"
  17
  18 namespace net {
  19
  20 class CryptoFramer;
  21 class QuicData;
  22 class QuicDataReader;
  23 class QuicDataWriter;
  24
  25 class NET_EXPORT_PRIVATE CryptoFramerVisitorInterface {
  26  public:
  27   virtual ~CryptoFramerVisitorInterface() {}
  28
  29   // Called if an error is detected.
  30   virtual void OnError(CryptoFramer* framer) = 0;
  31
  32   // Called when a complete handshake message has been parsed.
  33   virtual void OnHandshakeMessage(const CryptoHandshakeMessage& message) = 0;
  34 };
  35
  36 // A class for framing the crypto messages that are exchanged in a QUIC
  37 // session.
  38 class NET_EXPORT_PRIVATE CryptoFramer {
  39  public:
  40   CryptoFramer();
  41
  42   virtual ~CryptoFramer();
  43
  44   // ParseMessage parses exactly one message from the given StringPiece. If
  45   // there is an error, the message is truncated, or the message has trailing
  46   // garbage then nullptr will be returned.
  47   static CryptoHandshakeMessage* ParseMessage(base::StringPiece in);
  48
  49   // Set callbacks to be called from the framer.  A visitor must be set, or
  50   // else the framer will crash.  It is acceptable for the visitor to do
  51   // nothing.  If this is called multiple times, only the last visitor
  52   // will be used.  |visitor| will be owned by the framer.
  53   void set_visitor(CryptoFramerVisitorInterface* visitor) {
  54     visitor_ = visitor;
  55   }
  56
  57   QuicErrorCode error() const { return error_; }
  58
  59   // Processes input data, which must be delivered in order. Returns
  60   // false if there was an error, and true otherwise.
  61   bool ProcessInput(base::StringPiece input);
  62
  63   // Returns the number of bytes of buffered input data remaining to be
  64   // parsed.
  65   size_t InputBytesRemaining() const { return buffer_.length(); }
  66
  67   // Returns a new QuicData owned by the caller that contains a serialized
  68   // |message|, or nullptr if there was an error.
  69   static QuicData* ConstructHandshakeMessage(
  70       const CryptoHandshakeMessage& message);
  71
  72  private:
  73   // Clears per-message state.  Does not clear the visitor.
  74   void Clear();
  75
  76   // Process does does the work of |ProcessInput|, but returns an error code,
  77   // doesn't set error_ and doesn't call |visitor_->OnError()|.
  78   QuicErrorCode Process(base::StringPiece input);
  79
  80   static bool WritePadTag(QuicDataWriter* writer,
  81                           size_t pad_length,
  82                           uint32* end_offset);
  83
  84   // Represents the current state of the parsing state machine.
  85   enum CryptoFramerState {
  86     STATE_READING_TAG,
  87     STATE_READING_NUM_ENTRIES,
  88     STATE_READING_TAGS_AND_LENGTHS,
  89     STATE_READING_VALUES
  90   };
  91
  92   // Visitor to invoke when messages are parsed.
  93   CryptoFramerVisitorInterface* visitor_;
  94   // Last error.
  95   QuicErrorCode error_;
  96   // Remaining unparsed data.
  97   std::string buffer_;
  98   // Current state of the parsing.
  99   CryptoFramerState state_;
 100   // The message currently being parsed.
 101   CryptoHandshakeMessage message_;
 102   // Number of entires in the message currently being parsed.
 103   uint16 num_entries_;
 104   // tags_and_lengths_ contains the tags that are currently being parsed and
 105   // their lengths.
 106   std::vector<std::pair<QuicTag, size_t> > tags_and_lengths_;
 107   // Cumulative length of all values in the message currently being parsed.
 108   size_t values_len_;
 109 };
 110
 111 }  // namespace net
 112
 113 #endif  // NET_QUIC_CRYPTO_CRYPTO_FRAMER_H_