net/quic/crypto/cert_compressor.h

   1 // Copyright (c) 2013 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_CERT_COMPRESSOR_H_
   6 #define NET_QUIC_CRYPTO_CERT_COMPRESSOR_H_
   7
   8 #include <string>
   9 #include <vector>
  10
  11 #include "base/basictypes.h"
  12 #include "base/strings/string_piece.h"
  13 #include "net/base/net_export.h"
  14 #include "net/quic/crypto/common_cert_set.h"
  15 #include "net/quic/crypto/crypto_protocol.h"
  16
  17 namespace net {
  18
  19 // CertCompressor provides functions for compressing and decompressing
  20 // certificate chains using three techniquies:
  21 //   1) The peer may provide a list of a 64-bit, FNV-1a hashes of certificates
  22 //      that they already have. In the event that one of them is to be
  23 //      compressed, it can be replaced with just the hash.
  24 //   2) The peer may provide a number of hashes that represent sets of
  25 //      pre-shared certificates (CommonCertSets). If one of those certificates
  26 //      is to be compressed, and it's known to the given CommonCertSets, then it
  27 //      can be replaced with a set hash and certificate index.
  28 //   3) Otherwise the certificates are compressed with zlib using a pre-shared
  29 //      dictionary that consists of the certificates handled with the above
  30 //      methods and a small chunk of common substrings.
  31 class NET_EXPORT_PRIVATE CertCompressor {
  32  public:
  33   // CompressChain compresses the certificates in |certs| and returns a
  34   // compressed representation. |common_sets| contains the common certificate
  35   // sets known locally and |client_common_set_hashes| contains the hashes of
  36   // the common sets known to the peer. |client_cached_cert_hashes| contains
  37   // 64-bit, FNV-1a hashes of certificates that the peer already possesses.
  38   static std::string CompressChain(const std::vector<std::string>& certs,
  39                                    base::StringPiece client_common_set_hashes,
  40                                    base::StringPiece client_cached_cert_hashes,
  41                                    const CommonCertSets* common_sets);
  42
  43   // DecompressChain decompresses the result of |CompressChain|, given in |in|,
  44   // into a series of certificates that are written to |out_certs|.
  45   // |cached_certs| contains certificates that the peer may have omitted and
  46   // |common_sets| contains the common certificate sets known locally.
  47   static bool DecompressChain(base::StringPiece in,
  48                               const std::vector<std::string>& cached_certs,
  49                               const CommonCertSets* common_sets,
  50                               std::vector<std::string>* out_certs);
  51
  52  private:
  53   DISALLOW_COPY_AND_ASSIGN(CertCompressor);
  54 };
  55
  56 }  // namespace net
  57
  58 #endif  // NET_QUIC_CRYPTO_CERT_COMPRESSOR_H_