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// 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 <string>
#include <vector>
#include <sys/types.h>
#include "base/basictypes.h"
#include "base/memory/scoped_ptr.h"
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 version;
uint32 key_size; // The size of the public key, in bytes.
uint32 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 scoped_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 scoped_ptr<CrxFile> Create(const uint32 key_size,
const uint32 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_
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