net/spdy/spdy_headers_block_parser.h

   1 // Copyright 2014 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_SPDY_SPDY_HEADERS_BLOCK_PARSER_H_
   6 #define NET_SPDY_SPDY_HEADERS_BLOCK_PARSER_H_
   7
   8 #include "base/logging.h"
   9 #include "base/memory/scoped_ptr.h"
  10 #include "base/strings/string_piece.h"
  11 #include "net/base/net_export.h"
  12 #include "net/spdy/spdy_prefixed_buffer_reader.h"
  13 #include "net/spdy/spdy_protocol.h"
  14
  15 namespace net {
  16
  17 // A handler class for SPDY headers.
  18 class SpdyHeadersHandlerInterface {
  19  public:
  20   virtual ~SpdyHeadersHandlerInterface() {}
  21
  22   // A callback method which notifies when the parser starts handling a new
  23   // SPDY headers block, this method also notifies on the number of headers in
  24   // the block.
  25   virtual void OnHeaderBlock(uint32_t num_of_headers) = 0;
  26
  27   // A callback method which notifies on a SPDY header key value pair.
  28   virtual void OnHeader(base::StringPiece key, base::StringPiece value) = 0;
  29
  30   // A callback method which notifies when the parser finishes handling a SPDY
  31   // headers block. Also notifies on the total number of bytes in this block.
  32   virtual void OnHeaderBlockEnd(size_t header_bytes_parsed) = 0;
  33 };
  34
  35 namespace test {
  36
  37 class SpdyHeadersBlockParserPeer;
  38
  39 }  // namespace test
  40
  41 // This class handles SPDY headers block bytes and parses out key-value pairs
  42 // as they arrive. This class is not thread-safe, and assumes that all headers
  43 // block bytes are processed in a single thread.
  44 class NET_EXPORT_PRIVATE SpdyHeadersBlockParser {
  45  public:
  46   // Bound on acceptable header name or value length.
  47   static const size_t kMaximumFieldLength;  // = 16 * 1024
  48
  49   // Constructor. The handler's OnHeader will be called for every key
  50   // value pair that we parsed from the headers block.
  51   SpdyHeadersBlockParser(SpdyMajorVersion spdy_version,
  52                          SpdyHeadersHandlerInterface* handler);
  53
  54   virtual ~SpdyHeadersBlockParser();
  55
  56   // Handles headers block data as it arrives. Returns false if an error has
  57   // been set, which can include the recoverable error NEED_MORE_DATA. Returns
  58   // true if the invocation completes the parse of the entire headers block,
  59   // in which case the parser is ready for a new headers block.
  60   bool HandleControlFrameHeadersData(SpdyStreamId stream_id,
  61                                      const char* headers_data,
  62                                      size_t len);
  63   enum ParserError {
  64     NO_PARSER_ERROR,
  65     // Set when parsing failed due to insufficient data.
  66     // This error is recoverable, by passing in new data.
  67     NEED_MORE_DATA,
  68     // Set when a complete block has been read, but unprocessed data remains.
  69     TOO_MUCH_DATA,
  70     // Set when a block exceeds |MaxNumberOfHeadersForVersion| headers.
  71     HEADER_BLOCK_TOO_LARGE,
  72     // Set when a header key or value exceeds |kMaximumFieldLength|.
  73     HEADER_FIELD_TOO_LARGE,
  74     // Set when the parser is given an unexpected stream ID.
  75     UNEXPECTED_STREAM_ID,
  76   };
  77   ParserError get_error() const { return error_; }
  78
  79   SpdyMajorVersion spdy_version() const { return spdy_version_; }
  80
  81   // Returns the size in bytes of a length field in a SPDY header.
  82   static size_t LengthFieldSizeForVersion(SpdyMajorVersion spdy_version);
  83
  84   // Returns the maximal number of headers in a SPDY headers block.
  85   static size_t MaxNumberOfHeadersForVersion(SpdyMajorVersion spdy_version);
  86
  87  private:
  88   typedef SpdyPrefixedBufferReader Reader;
  89
  90   // Parses and sanity-checks header block length.
  91   void ParseBlockLength(Reader* reader);
  92
  93   // Parses and sanity-checks header field length.
  94   void ParseFieldLength(Reader* reader);
  95
  96   // Parses and decodes network-order lengths into |parsed_length|.
  97   void ParseLength(Reader* reader, uint32_t* parsed_length);
  98
  99   // The state of the parser.
 100   enum ParserState {
 101     READING_HEADER_BLOCK_LEN,
 102     READING_KEY_LEN,
 103     READING_KEY,
 104     READING_VALUE_LEN,
 105     READING_VALUE,
 106     FINISHED_HEADER
 107   };
 108   ParserState state_;
 109
 110   // Size in bytes of a length field in the spdy header.
 111   const size_t length_field_size_;
 112
 113   // The maximal number of headers in a SPDY headers block.
 114   const size_t max_headers_in_block_;
 115
 116   // A running total of the bytes parsed since the last call to Reset().
 117   size_t total_bytes_received_;
 118
 119   // Number of key-value pairs until we complete handling the current
 120   // headers block.
 121   uint32_t remaining_key_value_pairs_for_frame_;
 122
 123   // The length of the next header field to be read (either key or value).
 124   uint32_t next_field_length_;
 125
 126   // Handles key-value pairs as we parse them.
 127   SpdyHeadersHandlerInterface* handler_;
 128
 129   // Holds unprocessed buffer remainders between calls to
 130   // |HandleControlFrameHeadersData|.
 131   SpdyPinnableBufferPiece headers_block_prefix_;
 132
 133   // Holds the key of a partially processed header between calls to
 134   // |HandleControlFrameHeadersData|.
 135   SpdyPinnableBufferPiece key_;
 136
 137   // The current header block stream identifier.
 138   SpdyStreamId stream_id_;
 139
 140   ParserError error_;
 141
 142   const SpdyMajorVersion spdy_version_;
 143 };
 144
 145 }  // namespace net
 146
 147 #endif  // NET_SPDY_SPDY_HEADERS_BLOCK_PARSER_H_