// Copyright (c) 2011 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/cert_library.h"

#include <algorithm>

#include "base/observer_list_threadsafe.h"
#include "base/utf_string_conversions.h"
#include "chrome/browser/browser_process.h"  // g_browser_process
#include "chrome/browser/chromeos/login/user_manager.h"
#include "chrome/common/net/x509_certificate_model.h"
#include "content/browser/browser_thread.h"
#include "crypto/nss_util.h"
#include "net/base/cert_database.h"
#include "ui/base/l10n/l10n_util_collator.h"
#include "unicode/coll.h"  // icu::Collator

//////////////////////////////////////////////////////////////////////////////

namespace {

// Root CA certificates that are built into Chrome use this token name.
const char kRootCertificateTokenName[] = "Builtin Object Token";

// Delay between certificate requests while waiting for TPM/PKCS#11 init.
const int kRequestDelayMs = 500;

string16 GetDisplayString(net::X509Certificate* cert) {
  std::string name_or_nick =
      x509_certificate_model::GetCertNameOrNickname(cert->os_cert_handle());
  return UTF8ToUTF16(name_or_nick);
}

}  // namespace

//////////////////////////////////////////////////////////////////////////////

namespace chromeos {

//////////////////////////////////////////////////////////////////////////////

class CertLibraryImpl
    : public CertLibrary,
      public net::CertDatabase::Observer {
 public:
  typedef ObserverListThreadSafe<CertLibrary::Observer> CertLibraryObserverList;

  CertLibraryImpl() :
      observer_list_(new CertLibraryObserverList),
      request_task_(NULL),
      user_logged_in_(false),
      certificates_loaded_(false) {
    CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
    net::CertDatabase::AddObserver(this);
  }

  ~CertLibraryImpl() {
    CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
    if (request_task_) {
      request_task_->Cancel();
      request_task_ = NULL;
    }
    net::CertDatabase::RemoveObserver(this);
  }

  // CertLibrary implementation.
  virtual void RequestCertificates() OVERRIDE {
    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));

    if (!UserManager::Get()->user_is_logged_in()) {
      // If we are not logged in, we cannot load any certificates.
      // Set 'loaded' to true for the UI, since we are not waiting on loading.
      LOG(WARNING) << "Requesting certificates before login.";
      certificates_loaded_ = true;
      return;
    }

    if (!user_logged_in_) {
      user_logged_in_ = true;
      certificates_loaded_ = false;
    }

    VLOG(1) << "Requesting Certificates.";

    // Need TPM token name to filter user certificates.
    // TODO(stevenjb): crypto::EnsureTPMTokenReady() may block if init has
    // not succeeded. It is not clear whether or not TPM / PKCS#11 init can
    // be done safely on a non blocking thread. Blocking time is low.
    if (crypto::EnsureTPMTokenReady()) {
      std::string unused_pin;
      // TODO(stevenjb): Make this asynchronous. It results in a synchronous
      // D-Bus call in cryptohome (~3 ms).
      crypto::GetTPMTokenInfo(&tpm_token_name_, &unused_pin);
    } else {
      if (crypto::IsTPMTokenAvailable()) {
        VLOG(1) << "TPM token not ready.";
        if (request_task_ == NULL) {
          // Cryptohome does not notify us when the token is ready, so call
          // this again after a delay.
          request_task_ = NewRunnableMethod(
              this, &CertLibraryImpl::RequestCertificatesTask);
          BrowserThread::PostDelayedTask(
              BrowserThread::UI, FROM_HERE, request_task_, kRequestDelayMs);
        }
        return;
      }
      // TPM is not enabled, so proceed with empty tpm token name.
      VLOG(1) << "TPM not available.";
    }

    // tpm_token_name_ is set, load the certificates on the DB thread.
    BrowserThread::PostTask(
        BrowserThread::DB, FROM_HERE,
        NewRunnableMethod(this, &CertLibraryImpl::LoadCertificates));
  }

  virtual void AddObserver(CertLibrary::Observer* observer) OVERRIDE {
    observer_list_->AddObserver(observer);
  }

  virtual void RemoveObserver(CertLibrary::Observer* observer) OVERRIDE {
    observer_list_->RemoveObserver(observer);
  }

  virtual bool CertificatesLoaded() const OVERRIDE {
    return certificates_loaded_;
  }

  virtual const CertList& GetCertificates() const OVERRIDE {
    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
    return certs_;
  }

  virtual const CertList& GetUserCertificates() const OVERRIDE {
    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
    return user_certs_;
  }

  virtual const CertList& GetServerCertificates() const OVERRIDE {
    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
    return server_certs_;
  }

  virtual const CertList& GetCACertificates() const OVERRIDE {
    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
    return server_ca_certs_;
  }

  // net::CertDatabase::Observer implementation. Observer added on UI thread.
  virtual void OnCertTrustChanged(const net::X509Certificate* cert) OVERRIDE {
    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  }

  virtual void OnUserCertAdded(const net::X509Certificate* cert) OVERRIDE {
    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
    VLOG(1) << "Certificate Added.";
    // Only load certificates if we have completed an initial request.
    if (certificates_loaded_) {
      VLOG(1) << " Loading Certificates.";
      // The certificate passed in is const, so we cannot add it to our
      // ref counted list directly. Instead, re-load the certificate list.
      BrowserThread::PostTask(
          BrowserThread::DB, FROM_HERE,
          NewRunnableMethod(this, &CertLibraryImpl::LoadCertificates));
    }
  }

 private:
  void LoadCertificates() {
    // Certificate fetch occurs on the DB thread.
    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::DB));
    net::CertDatabase cert_db;
    net::CertificateList* cert_list = new net::CertificateList();
    cert_db.ListCerts(cert_list);
    // Pass the list to the UI thread to safely update the local lists.
    BrowserThread::PostTask(
        BrowserThread::UI, FROM_HERE,
        NewRunnableMethod(this, &CertLibraryImpl::UpdateCertificates,
                          cert_list));
  }

  // Comparison functor for locale-sensitive sorting of certificates by name.
  class CertNameComparator {
   public:
    explicit CertNameComparator(icu::Collator* collator)
        : collator_(collator) { }

    bool operator()(const scoped_refptr<net::X509Certificate>& lhs,
                    const scoped_refptr<net::X509Certificate>& rhs) const {
      string16 lhs_name = GetDisplayString(lhs.get());
      string16 rhs_name = GetDisplayString(rhs.get());
      if (collator_ == NULL)
        return lhs_name < rhs_name;
      return l10n_util::CompareString16WithCollator(
          collator_, lhs_name, rhs_name) == UCOL_LESS;
    }
   private:
    icu::Collator* collator_;
  };

  void RequestCertificatesTask() {
    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
    // This will only get called from request_task_ which will delete itself.
    request_task_ = NULL;
    RequestCertificates();
  }

  void NotifyCertificatesLoaded(bool initial_load) {
    observer_list_->Notify(
        &CertLibrary::Observer::OnCertificatesLoaded, initial_load);
  }

  // |cert_list| is allocated in LoadCertificates() and must be deleted here.
  void UpdateCertificates(net::CertificateList* cert_list) {
    DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
    DCHECK(cert_list);

    // Clear any existing certificates.
    certs_.Clear();
    server_ca_certs_.Clear();
    user_certs_.Clear();
    server_certs_.Clear();

    // Add certificates to the appropriate list.
    for (net::CertificateList::const_iterator iter = cert_list->begin();
         iter != cert_list->end(); ++iter) {
      certs_.Append(iter->get());
      net::X509Certificate::OSCertHandle cert_handle =
          iter->get()->os_cert_handle();
      net::CertType type = x509_certificate_model::GetType(cert_handle);
      switch (type) {
        case net::USER_CERT: {
          // Only include user certs that are in the TPM token (and hence
          // available via PKCS#11 to flimflam and wpa_supplicant).
          std::string cert_token_name =
              x509_certificate_model::GetTokenName(cert_handle);
          if (tpm_token_name_.empty() || cert_token_name == tpm_token_name_)
            user_certs_.Append(iter->get());
          break;
        }
        case net::SERVER_CERT:
          server_certs_.Append(iter->get());
          break;
        case net::CA_CERT: {
          // Exclude root CA certificates that are built into Chrome.
          std::string token_name =
              x509_certificate_model::GetTokenName(cert_handle);
          if (token_name != kRootCertificateTokenName)
            server_ca_certs_.Append(iter->get());
          break;
        }
        default:
          break;
      }
    }

    // Perform locale-sensitive sorting by certificate name.
    scoped_ptr<icu::Collator> collator;
    UErrorCode error = U_ZERO_ERROR;
    collator.reset(
        icu::Collator::createInstance(
            icu::Locale(g_browser_process->GetApplicationLocale().c_str()),
            error));
    if (U_FAILURE(error))
      collator.reset(NULL);
    CertNameComparator cert_name_comparator(collator.get());
    std::sort(user_certs_.list().begin(), user_certs_.list().end(),
              cert_name_comparator);
    std::sort(server_certs_.list().begin(), server_certs_.list().end(),
              cert_name_comparator);
    std::sort(server_ca_certs_.list().begin(), server_ca_certs_.list().end(),
              cert_name_comparator);

    // cert_list is allocated in LoadCertificates(), then released here.
    delete cert_list;

    // Set loaded state and notify observers.
    if (!certificates_loaded_) {
      certificates_loaded_ = true;
      NotifyCertificatesLoaded(true);
    } else {
      NotifyCertificatesLoaded(false);
    }
  }

  // Observers.
  const scoped_refptr<CertLibraryObserverList> observer_list_;

  // Active request task for re-requests while waiting for TPM init.
  CancelableTask* request_task_;

  // Cached TPM token name.
  std::string tpm_token_name_;

  // Local state.
  bool user_logged_in_;
  bool certificates_loaded_;

  // Certificates.
  CertList certs_;
  CertList user_certs_;
  CertList server_certs_;
  CertList server_ca_certs_;

  DISALLOW_COPY_AND_ASSIGN(CertLibraryImpl);
};

//////////////////////////////////////////////////////////////////////////////

CertLibrary::~CertLibrary() {
}

// static
CertLibrary* CertLibrary::GetImpl(bool stub) {
  // No libcros dependencies, so always return CertLibraryImpl() (no stub).
  return new CertLibraryImpl();
}

//////////////////////////////////////////////////////////////////////////////

net::X509Certificate* CertLibrary::CertList::GetCertificateAt(int index) const {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
  DCHECK_GE(index, 0);
  DCHECK_LT(index, static_cast<int>(list_.size()));
  return list_[index].get();
}

string16 CertLibrary::CertList::GetDisplayStringAt(int index) const {
  net::X509Certificate* cert = GetCertificateAt(index);
  return GetDisplayString(cert);
}

std::string CertLibrary::CertList::GetNicknameAt(int index) const {
  net::X509Certificate* cert = GetCertificateAt(index);
  return x509_certificate_model::GetNickname(cert->os_cert_handle());
}

std::string CertLibrary::CertList::GetPkcs11IdAt(int index) const {
  net::X509Certificate* cert = GetCertificateAt(index);
  return x509_certificate_model::GetPkcs11Id(cert->os_cert_handle());
}

int CertLibrary::CertList::FindCertByNickname(
    const std::string& nickname) const {
  for (int index = 0; index < Size(); ++index) {
    net::X509Certificate* cert = GetCertificateAt(index);
    net::X509Certificate::OSCertHandle cert_handle = cert->os_cert_handle();
    std::string nick = x509_certificate_model::GetNickname(cert_handle);
    if (nick == nickname)
      return index;
  }
  return -1;  // Not found.
}

int CertLibrary::CertList::FindCertByPkcs11Id(
    const std::string& pkcs11_id) const {
  for (int index = 0; index < Size(); ++index) {
    net::X509Certificate* cert = GetCertificateAt(index);
    net::X509Certificate::OSCertHandle cert_handle = cert->os_cert_handle();
    std::string id = x509_certificate_model::GetPkcs11Id(cert_handle);
    if (id == pkcs11_id)
      return index;
  }
  return -1;  // Not found.
}

}  // chromeos

// Allows InvokeLater without adding refcounting. This class is a singleton and
// won't be deleted until it's last InvokeLater is run.
DISABLE_RUNNABLE_METHOD_REFCOUNT(chromeos::CertLibraryImpl);