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 COMPONENTS_CRX_FILE_CRX_FILE_H_ 6 #define COMPONENTS_CRX_FILE_CRX_FILE_H_ 7 8 #include <sys/types.h> 9 #include "base/basictypes.h" 10 #include "base/memory/scoped_ptr.h" 11 12 namespace crx_file { 13 14 // CRX files have a header that includes a magic key, version number, and 15 // some signature sizing information. Use CrxFile object to validate whether 16 // the header is valid or not. 17 class CrxFile { 18 public: 19 // The size of the magic character sequence at the beginning of each crx 20 // file, in bytes. This should be a multiple of 4. 21 static const size_t kCrxFileHeaderMagicSize = 4; 22 23 // This header is the first data at the beginning of an extension. Its 24 // contents are purposely 32-bit aligned so that it can just be slurped into 25 // a struct without manual parsing. 26 struct Header { 27 char magic[kCrxFileHeaderMagicSize]; 28 uint32 version; 29 uint32 key_size; // The size of the public key, in bytes. 30 uint32 signature_size; // The size of the signature, in bytes. 31 // An ASN.1-encoded PublicKeyInfo structure follows. 32 // The signature follows. 33 }; 34 35 enum Error { 36 kWrongMagic, 37 kInvalidVersion, 38 kInvalidKeyTooLarge, 39 kInvalidKeyTooSmall, 40 kInvalidSignatureTooLarge, 41 kInvalidSignatureTooSmall, 42 }; 43 44 // Construct a new CRX file header object with bytes of a header 45 // read from a CRX file. If a null scoped_ptr is returned, |error| 46 // contains an error code with additional information. 47 static scoped_ptr<CrxFile> Parse(const Header& header, Error* error); 48 49 // Construct a new header for the given key and signature sizes. 50 // Returns a null scoped_ptr if erroneous values of |key_size| and/or 51 // |signature_size| are provided. |error| contains an error code with 52 // additional information. 53 // Use this constructor and then .header() to obtain the Header 54 // for writing out to a CRX file. 55 static scoped_ptr<CrxFile> Create(const uint32 key_size, 56 const uint32 signature_size, 57 Error* error); 58 59 // Returns the header structure for writing out to a CRX file. header()60 const Header& header() const { return header_; } 61 62 // Checks a valid |header| to determine whether or not the CRX represents a 63 // differential CRX. 64 static bool HeaderIsDelta(const Header& header); 65 66 private: 67 Header header_; 68 69 // Constructor is private. Clients should use static factory methods above. 70 explicit CrxFile(const Header& header); 71 72 // Checks the |header| for validity and returns true if the values are valid. 73 // If false is returned, more detailed error code is returned in |error|. 74 static bool HeaderIsValid(const Header& header, Error* error); 75 }; 76 77 } // namespace crx_file 78 79 #endif // COMPONENTS_CRX_FILE_CRX_FILE_H_ 80