extensions/common/crx_file.cc

   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 #include "extensions/common/crx_file.h"
   6
   7 namespace extensions {
   8
   9 namespace {
  10
  11 // The current version of the crx format.
  12 static const uint32 kCurrentVersion = 2;
  13
  14 // The current version of the crx diff format.
  15 static const uint32 kCurrentDiffVersion = 0;
  16
  17 // The maximum size the crx parser will tolerate for a public key.
  18 static const uint32 kMaxPublicKeySize = 1 << 16;
  19
  20 // The maximum size the crx parser will tolerate for a signature.
  21 static const uint32 kMaxSignatureSize = 1 << 16;
  22
  23 }  // namespace
  24
  25 // The magic string embedded in the header.
  26 const char kCrxFileHeaderMagic[] = "Cr24";
  27 const char kCrxDiffFileHeaderMagic[] = "CrOD";
  28
  29 scoped_ptr<CrxFile> CrxFile::Parse(const CrxFile::Header& header,
  30                                    CrxFile::Error* error) {
  31   if (HeaderIsValid(header, error))
  32     return scoped_ptr<CrxFile>(new CrxFile(header));
  33   return scoped_ptr<CrxFile>();
  34 }
  35
  36 scoped_ptr<CrxFile> CrxFile::Create(const uint32 key_size,
  37                                     const uint32 signature_size,
  38                                     CrxFile::Error* error) {
  39   CrxFile::Header header;
  40   memcpy(&header.magic, kCrxFileHeaderMagic, kCrxFileHeaderMagicSize);
  41   header.version = kCurrentVersion;
  42   header.key_size = key_size;
  43   header.signature_size = signature_size;
  44   if (HeaderIsValid(header, error))
  45     return scoped_ptr<CrxFile>(new CrxFile(header));
  46   return scoped_ptr<CrxFile>();
  47 }
  48
  49 CrxFile::CrxFile(const Header& header) : header_(header) {
  50 }
  51
  52 bool CrxFile::HeaderIsDelta(const CrxFile::Header& header) {
  53   return !strncmp(kCrxDiffFileHeaderMagic, header.magic, sizeof(header.magic));
  54 }
  55
  56 bool CrxFile::HeaderIsValid(const CrxFile::Header& header,
  57                             CrxFile::Error* error) {
  58   bool valid = false;
  59   bool diffCrx = false;
  60   if (!strncmp(kCrxDiffFileHeaderMagic, header.magic, sizeof(header.magic)))
  61     diffCrx = true;
  62   if (strncmp(kCrxFileHeaderMagic, header.magic, sizeof(header.magic)) &&
  63       !diffCrx)
  64     *error = kWrongMagic;
  65   else if (header.version != kCurrentVersion
  66       && !(diffCrx && header.version == kCurrentDiffVersion))
  67     *error = kInvalidVersion;
  68   else if (header.key_size > kMaxPublicKeySize)
  69     *error = kInvalidKeyTooLarge;
  70   else if (header.key_size == 0)
  71     *error = kInvalidKeyTooSmall;
  72   else if (header.signature_size > kMaxSignatureSize)
  73     *error = kInvalidSignatureTooLarge;
  74   else if (header.signature_size == 0)
  75     *error = kInvalidSignatureTooSmall;
  76   else
  77     valid = true;
  78   return valid;
  79 }
  80
  81 }  // namespace extensions