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