// Copyright (c) 2012 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.

#include "chrome/browser/chromeos/cros/cryptohome_library.h"

#include "base/command_line.h"
#include "base/message_loop.h"
#include "base/string_number_conversions.h"
#include "base/string_util.h"
#include "chrome/common/chrome_switches.h"
#include "chromeos/dbus/cryptohome_client.h"
#include "chromeos/dbus/dbus_thread_manager.h"
#include "content/public/browser/browser_thread.h"
#include "crypto/encryptor.h"
#include "crypto/sha2.h"

using content::BrowserThread;

namespace {

const char kStubSystemSalt[] = "stub_system_salt";
const int kPassHashLen = 32;

}

namespace chromeos {

// This class handles the interaction with the ChromeOS cryptohome library APIs.
class CryptohomeLibraryImpl : public CryptohomeLibrary {
 public:
  CryptohomeLibraryImpl() : weak_ptr_factory_(this) {
  }

  virtual ~CryptohomeLibraryImpl() {
  }

  virtual bool IsMounted() OVERRIDE {
    bool result = false;
    DBusThreadManager::Get()->GetCryptohomeClient()->IsMounted(&result);
    return result;
  }

  virtual bool TpmIsReady() OVERRIDE {
    bool result = false;
    DBusThreadManager::Get()->GetCryptohomeClient()->TpmIsReady(&result);
    return result;
  }

  virtual bool TpmIsEnabled() OVERRIDE {
    bool result = false;
    DBusThreadManager::Get()->GetCryptohomeClient()->CallTpmIsEnabledAndBlock(
        &result);
    return result;
  }

  virtual bool TpmIsOwned() OVERRIDE {
    bool result = false;
    DBusThreadManager::Get()->GetCryptohomeClient()->TpmIsOwned(&result);
    return result;
  }

  virtual bool TpmIsBeingOwned() OVERRIDE {
    bool result = false;
    DBusThreadManager::Get()->GetCryptohomeClient()->TpmIsBeingOwned(&result);
    return result;
  }

  virtual bool TpmGetPassword(std::string* password) OVERRIDE {
    return DBusThreadManager::Get()->GetCryptohomeClient()->
        TpmGetPassword(password);
  }

  virtual void TpmCanAttemptOwnership() OVERRIDE {
    DBusThreadManager::Get()->GetCryptohomeClient()->TpmCanAttemptOwnership();
  }

  virtual void TpmClearStoredPassword() OVERRIDE {
    DBusThreadManager::Get()->GetCryptohomeClient()->TpmClearStoredPassword();
  }

  virtual bool InstallAttributesGet(
      const std::string& name, std::string* value) OVERRIDE {
    std::vector<uint8> buf;
    bool success = false;
    DBusThreadManager::Get()->GetCryptohomeClient()->
        InstallAttributesGet(name, &buf, &success);
    if (success) {
      // Cryptohome returns 'buf' with a terminating '\0' character.
      DCHECK(!buf.empty());
      DCHECK_EQ(buf.back(), 0);
      value->assign(reinterpret_cast<char*>(buf.data()), buf.size() - 1);
    }
    return success;
  }

  virtual bool InstallAttributesSet(
      const std::string& name, const std::string& value) OVERRIDE {
    std::vector<uint8> buf(value.c_str(), value.c_str() + value.size() + 1);
    bool success = false;
    DBusThreadManager::Get()->GetCryptohomeClient()->
        InstallAttributesSet(name, buf, &success);
    return success;
  }

  virtual bool InstallAttributesFinalize() OVERRIDE {
    bool success = false;
    DBusThreadManager::Get()->GetCryptohomeClient()->
        InstallAttributesFinalize(&success);
    return success;
  }

  virtual bool InstallAttributesIsReady() OVERRIDE {
    bool result = false;
    DBusThreadManager::Get()->GetCryptohomeClient()->
        InstallAttributesIsReady(&result);
    return result;
  }

  virtual bool InstallAttributesIsInvalid() OVERRIDE {
    bool result = false;
    DBusThreadManager::Get()->GetCryptohomeClient()->
        InstallAttributesIsInvalid(&result);
    return result;
  }

  virtual bool InstallAttributesIsFirstInstall() OVERRIDE {
    bool result = false;
    DBusThreadManager::Get()->GetCryptohomeClient()->
        InstallAttributesIsFirstInstall(&result);
    return result;
  }

  virtual std::string HashPassword(const std::string& password) OVERRIDE {
    // Get salt, ascii encode, update sha with that, then update with ascii
    // of password, then end.
    std::string ascii_salt = GetSystemSalt();
    char passhash_buf[kPassHashLen];

    // Hash salt and password
    crypto::SHA256HashString(ascii_salt + password,
                             &passhash_buf, sizeof(passhash_buf));

    return StringToLowerASCII(base::HexEncode(
        reinterpret_cast<const void*>(passhash_buf),
        sizeof(passhash_buf) / 2));
  }

  virtual std::string GetSystemSalt() OVERRIDE {
    LoadSystemSalt();  // no-op if it's already loaded.
    return StringToLowerASCII(base::HexEncode(
        reinterpret_cast<const void*>(system_salt_.data()),
        system_salt_.size()));
  }

 private:
  void LoadSystemSalt() {
    if (!system_salt_.empty())
      return;
    DBusThreadManager::Get()->GetCryptohomeClient()->
        GetSystemSalt(&system_salt_);
    CHECK(!system_salt_.empty());
    CHECK_EQ(system_salt_.size() % 2, 0U);
  }

  base::WeakPtrFactory<CryptohomeLibraryImpl> weak_ptr_factory_;
  std::vector<uint8> system_salt_;

  DISALLOW_COPY_AND_ASSIGN(CryptohomeLibraryImpl);
};

class CryptohomeLibraryStubImpl : public CryptohomeLibrary {
 public:
  CryptohomeLibraryStubImpl()
    : locked_(false) {}
  virtual ~CryptohomeLibraryStubImpl() {}

  virtual bool IsMounted() OVERRIDE {
    return true;
  }

  // Tpm begin ready after 20-th call.
  virtual bool TpmIsReady() OVERRIDE {
    static int counter = 0;
    return ++counter > 20;
  }

  virtual bool TpmIsEnabled() OVERRIDE {
    return true;
  }

  virtual bool TpmIsOwned() OVERRIDE {
    return true;
  }

  virtual bool TpmIsBeingOwned() OVERRIDE {
    return true;
  }

  virtual bool TpmGetPassword(std::string* password) OVERRIDE {
    *password = "Stub-TPM-password";
    return true;
  }

  virtual void TpmCanAttemptOwnership() OVERRIDE {}

  virtual void TpmClearStoredPassword() OVERRIDE {}

  virtual bool InstallAttributesGet(
      const std::string& name, std::string* value) OVERRIDE {
    if (install_attrs_.find(name) != install_attrs_.end()) {
      *value = install_attrs_[name];
      return true;
    }
    return false;
  }

  virtual bool InstallAttributesSet(
      const std::string& name, const std::string& value) OVERRIDE {
    install_attrs_[name] = value;
    return true;
  }

  virtual bool InstallAttributesFinalize() OVERRIDE {
    locked_ = true;
    return true;
  }

  virtual bool InstallAttributesIsReady() OVERRIDE {
    return true;
  }

  virtual bool InstallAttributesIsInvalid() OVERRIDE {
    return false;
  }

  virtual bool InstallAttributesIsFirstInstall() OVERRIDE {
    return !locked_;
  }

  virtual std::string HashPassword(const std::string& password) OVERRIDE {
    return StringToLowerASCII(base::HexEncode(
            reinterpret_cast<const void*>(password.data()),
            password.length()));
  }

  virtual std::string GetSystemSalt() OVERRIDE {
    return kStubSystemSalt;
  }

 private:
  std::map<std::string, std::string> install_attrs_;
  bool locked_;
  DISALLOW_COPY_AND_ASSIGN(CryptohomeLibraryStubImpl);
};

CryptohomeLibrary::CryptohomeLibrary() {}
CryptohomeLibrary::~CryptohomeLibrary() {}

// static
CryptohomeLibrary* CryptohomeLibrary::GetImpl(bool stub) {
  CryptohomeLibrary* impl;
  if (stub)
    impl = new CryptohomeLibraryStubImpl();
  else
    impl = new CryptohomeLibraryImpl();
  return impl;
}

} // namespace chromeos