Refactor CRX verification in preparation to support CRX₃ files.

components/crx_file/crx_file.h

-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef COMPONENTS_CRX_FILE_CRX_FILE_H_
-#define COMPONENTS_CRX_FILE_CRX_FILE_H_
-
-#include <stddef.h>
-#include <stdint.h>
-#include <sys/types.h>
-
-#include <memory>
-#include <string>
-#include <vector>
-
-namespace base {
-class FilePath;
-}
-
-namespace crx_file {
-
-// CRX files have a header that includes a magic key, version number, and
-// some signature sizing information. Use CrxFile object to validate whether
-// the header is valid or not.
-class CrxFile {
- public:
-  // The size of the magic character sequence at the beginning of each crx
-  // file, in bytes. This should be a multiple of 4.
-  static const size_t kCrxFileHeaderMagicSize = 4;
-
-  // This header is the first data at the beginning of an extension. Its
-  // contents are purposely 32-bit aligned so that it can just be slurped into
-  // a struct without manual parsing.
-  struct Header {
-    char magic[kCrxFileHeaderMagicSize];
-    uint32_t version;
-    uint32_t key_size;        // The size of the public key, in bytes.
-    uint32_t signature_size;  // The size of the signature, in bytes.
-    // An ASN.1-encoded PublicKeyInfo structure follows.
-    // The signature follows.
-  };
-
-  enum Error {
-    kWrongMagic,
-    kInvalidVersion,
-    kInvalidKeyTooLarge,
-    kInvalidKeyTooSmall,
-    kInvalidSignatureTooLarge,
-    kInvalidSignatureTooSmall,
-  };
-
-  // Construct a new CRX file header object with bytes of a header
-  // read from a CRX file. If a null scoped_ptr is returned, |error|
-  // contains an error code with additional information.
-  static std::unique_ptr<CrxFile> Parse(const Header& header, Error* error);
-
-  // Construct a new header for the given key and signature sizes.
-  // Returns a null scoped_ptr if erroneous values of |key_size| and/or
-  // |signature_size| are provided. |error| contains an error code with
-  // additional information.
-  // Use this constructor and then .header() to obtain the Header
-  // for writing out to a CRX file.
-  static std::unique_ptr<CrxFile> Create(const uint32_t key_size,
-                                         const uint32_t signature_size,
-                                         Error* error);
-
-  // Returns the header structure for writing out to a CRX file.
-  const Header& header() const { return header_; }
-
-  // Checks a valid |header| to determine whether or not the CRX represents a
-  // differential CRX.
-  static bool HeaderIsDelta(const Header& header);
-
-  enum class ValidateError {
-    NONE,
-    CRX_FILE_NOT_READABLE,
-    CRX_HEADER_INVALID,
-    CRX_MAGIC_NUMBER_INVALID,
-    CRX_VERSION_NUMBER_INVALID,
-    CRX_EXCESSIVELY_LARGE_KEY_OR_SIGNATURE,
-    CRX_ZERO_KEY_LENGTH,
-    CRX_ZERO_SIGNATURE_LENGTH,
-    CRX_PUBLIC_KEY_INVALID,
-    CRX_SIGNATURE_INVALID,
-    CRX_SIGNATURE_VERIFICATION_INITIALIZATION_FAILED,
-    CRX_SIGNATURE_VERIFICATION_FAILED,
-    CRX_HASH_VERIFICATION_FAILED,
-  };
-
-  // Validates that the .crx file at |crx_path| is properly signed.  If
-  // |expected_hash| is non-empty, it should specify a hex-encoded SHA256 hash
-  // for the entire .crx file which will be checked as we read it, and any
-  // mismatch will cause a CRX_HASH_VERIFICATION_FAILED result.  The
-  // |public_key| argument can be provided to receive a copy of the
-  // base64-encoded public key pem bytes extracted from the .crx. The
-  // |extension_id| argument can be provided to receive the extension id (which
-  // is computed as a hash of the public key provided in the .crx). The
-  // |header| argument can be provided to receive a copy of the crx header.
-  static ValidateError ValidateSignature(const base::FilePath& crx_path,
-                                         const std::string& expected_hash,
-                                         std::string* public_key,
-                                         std::string* extension_id,
-                                         CrxFile::Header* header);
-
- private:
-  Header header_;
-
-  // Constructor is private. Clients should use static factory methods above.
-  explicit CrxFile(const Header& header);
-
-  // Checks the |header| for validity and returns true if the values are valid.
-  // If false is returned, more detailed error code is returned in |error|.
-  static bool HeaderIsValid(const Header& header, Error* error);
-};
-
-}  // namespace crx_file
-
-#endif  // COMPONENTS_CRX_FILE_CRX_FILE_H_