net/extras/sqlite/sqlite_channel_id_store.cc - chromium/src - Git at Google

 // 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.

 #include "net/extras/sqlite/sqlite_channel_id_store.h"

 #include <set>

 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/scoped_vector.h"
 #include "base/metrics/histogram.h"
 #include "base/sequenced_task_runner.h"
 #include "base/strings/string_util.h"
 #include "net/cert/x509_certificate.h"
 #include "net/cookies/cookie_util.h"
 #include "net/ssl/ssl_client_cert_type.h"
 #include "sql/error_delegate_util.h"
 #include "sql/meta_table.h"
 #include "sql/statement.h"
 #include "sql/transaction.h"
 #include "url/gurl.h"

 namespace {

 // Version number of the database.
 const int kCurrentVersionNumber = 4;
 const int kCompatibleVersionNumber = 1;

 // Initializes the certs table, returning true on success.
 bool InitTable(sql::Connection* db) {
   // The table is named "origin_bound_certs" for backwards compatability before
   // we renamed this class to SQLiteChannelIDStore.  Likewise, the primary
   // key is "origin", but now can be other things like a plain domain.
   if (!db->DoesTableExist("origin_bound_certs")) {
     if (!db->Execute(
             "CREATE TABLE origin_bound_certs ("
             "origin TEXT NOT NULL UNIQUE PRIMARY KEY,"
             "private_key BLOB NOT NULL,"
             "cert BLOB NOT NULL,"
             "cert_type INTEGER,"
             "expiration_time INTEGER,"
             "creation_time INTEGER)")) {
       return false;
     }
   }

   return true;
 }

 }  // namespace

 namespace net {

 // This class is designed to be shared between any calling threads and the
 // background task runner. It batches operations and commits them on a timer.
 class SQLiteChannelIDStore::Backend
     : public base::RefCountedThreadSafe<SQLiteChannelIDStore::Backend> {
  public:
   Backend(
       const base::FilePath& path,
       const scoped_refptr<base::SequencedTaskRunner>& background_task_runner)
       : path_(path),
         num_pending_(0),
         force_keep_session_state_(false),
         background_task_runner_(background_task_runner),
         corruption_detected_(false) {}

   // Creates or loads the SQLite database.
   void Load(const LoadedCallback& loaded_callback);

   // Batch a channel ID addition.
   void AddChannelID(const DefaultChannelIDStore::ChannelID& channel_id);

   // Batch a channel ID deletion.
   void DeleteChannelID(const DefaultChannelIDStore::ChannelID& channel_id);

   // Post background delete of all channel ids for |server_identifiers|.
   void DeleteAllInList(const std::list<std::string>& server_identifiers);

   // Commit any pending operations and close the database.  This must be called
   // before the object is destructed.
   void Close();

   void SetForceKeepSessionState();

  private:
   friend class base::RefCountedThreadSafe<SQLiteChannelIDStore::Backend>;

   // You should call Close() before destructing this object.
   virtual ~Backend() {
     DCHECK(!db_.get()) << "Close should have already been called.";
     DCHECK_EQ(0u, num_pending_);
     DCHECK(pending_.empty());
   }

   void LoadInBackground(
       ScopedVector<DefaultChannelIDStore::ChannelID>* channel_ids);

   // Database upgrade statements.
   bool EnsureDatabaseVersion();

   class PendingOperation {
    public:
     enum OperationType { CHANNEL_ID_ADD, CHANNEL_ID_DELETE };

     PendingOperation(OperationType op,
                      const DefaultChannelIDStore::ChannelID& channel_id)
         : op_(op), channel_id_(channel_id) {}

     OperationType op() const { return op_; }
     const DefaultChannelIDStore::ChannelID& channel_id() const {
       return channel_id_;
     }

    private:
     OperationType op_;
     DefaultChannelIDStore::ChannelID channel_id_;
   };

  private:
   // Batch a channel id operation (add or delete).
   void BatchOperation(PendingOperation::OperationType op,
                       const DefaultChannelIDStore::ChannelID& channel_id);
   // Commit our pending operations to the database.
   void Commit();
   // Close() executed on the background task runner.
   void InternalBackgroundClose();

   void BackgroundDeleteAllInList(
       const std::list<std::string>& server_identifiers);

   void DatabaseErrorCallback(int error, sql::Statement* stmt);
   void KillDatabase();

   const base::FilePath path_;
   scoped_ptr<sql::Connection> db_;
   sql::MetaTable meta_table_;

   typedef std::list<PendingOperation*> PendingOperationsList;
   PendingOperationsList pending_;
   PendingOperationsList::size_type num_pending_;
   // True if the persistent store should skip clear on exit rules.
   bool force_keep_session_state_;
   // Guard |pending_|, |num_pending_| and |force_keep_session_state_|.
   base::Lock lock_;

   scoped_refptr<base::SequencedTaskRunner> background_task_runner_;

   // Indicates if the kill-database callback has been scheduled.
   bool corruption_detected_;

   DISALLOW_COPY_AND_ASSIGN(Backend);
 };

 void SQLiteChannelIDStore::Backend::Load(
     const LoadedCallback& loaded_callback) {
   // This function should be called only once per instance.
   DCHECK(!db_.get());
   scoped_ptr<ScopedVector<DefaultChannelIDStore::ChannelID> > channel_ids(
       new ScopedVector<DefaultChannelIDStore::ChannelID>());
   ScopedVector<DefaultChannelIDStore::ChannelID>* channel_ids_ptr =
       channel_ids.get();

   background_task_runner_->PostTaskAndReply(
       FROM_HERE,
       base::Bind(&Backend::LoadInBackground, this, channel_ids_ptr),
       base::Bind(loaded_callback, base::Passed(&channel_ids)));
 }

 void SQLiteChannelIDStore::Backend::LoadInBackground(
     ScopedVector<DefaultChannelIDStore::ChannelID>* channel_ids) {
   DCHECK(background_task_runner_->RunsTasksOnCurrentThread());

   // This method should be called only once per instance.
   DCHECK(!db_.get());

   base::TimeTicks start = base::TimeTicks::Now();

   // Ensure the parent directory for storing certs is created before reading
   // from it.
   const base::FilePath dir = path_.DirName();
   if (!base::PathExists(dir) && !base::CreateDirectory(dir))
     return;

   int64 db_size = 0;
   if (base::GetFileSize(path_, &db_size))
     UMA_HISTOGRAM_COUNTS("DomainBoundCerts.DBSizeInKB", db_size / 1024);

   db_.reset(new sql::Connection);
   db_->set_histogram_tag("DomainBoundCerts");

   // Unretained to avoid a ref loop with db_.
   db_->set_error_callback(
       base::Bind(&SQLiteChannelIDStore::Backend::DatabaseErrorCallback,
                  base::Unretained(this)));

   if (!db_->Open(path_)) {
     NOTREACHED() << "Unable to open cert DB.";
     if (corruption_detected_)
       KillDatabase();
     db_.reset();
     return;
   }

   if (!EnsureDatabaseVersion() || !InitTable(db_.get())) {
     NOTREACHED() << "Unable to open cert DB.";
     if (corruption_detected_)
       KillDatabase();
     meta_table_.Reset();
     db_.reset();
     return;
   }

   db_->Preload();

   // Slurp all the certs into the out-vector.
   sql::Statement smt(db_->GetUniqueStatement(
       "SELECT origin, private_key, cert, cert_type, expiration_time, "
       "creation_time FROM origin_bound_certs"));
   if (!smt.is_valid()) {
     if (corruption_detected_)
       KillDatabase();
     meta_table_.Reset();
     db_.reset();
     return;
   }

   while (smt.Step()) {
     SSLClientCertType type = static_cast<SSLClientCertType>(smt.ColumnInt(3));
     if (type != CLIENT_CERT_ECDSA_SIGN)
       continue;
     std::string private_key_from_db, cert_from_db;
     smt.ColumnBlobAsString(1, &private_key_from_db);
     smt.ColumnBlobAsString(2, &cert_from_db);
     scoped_ptr<DefaultChannelIDStore::ChannelID> channel_id(
         new DefaultChannelIDStore::ChannelID(
             smt.ColumnString(0),  // origin
             base::Time::FromInternalValue(smt.ColumnInt64(5)),
             base::Time::FromInternalValue(smt.ColumnInt64(4)),
             private_key_from_db,
             cert_from_db));
     channel_ids->push_back(channel_id.release());
   }

   UMA_HISTOGRAM_COUNTS_10000(
       "DomainBoundCerts.DBLoadedCount",
       static_cast<base::HistogramBase::Sample>(channel_ids->size()));
   base::TimeDelta load_time = base::TimeTicks::Now() - start;
   UMA_HISTOGRAM_CUSTOM_TIMES("DomainBoundCerts.DBLoadTime",
                              load_time,
                              base::TimeDelta::FromMilliseconds(1),
                              base::TimeDelta::FromMinutes(1),
                              50);
   DVLOG(1) << "loaded " << channel_ids->size() << " in "
            << load_time.InMilliseconds() << " ms";
 }

 bool SQLiteChannelIDStore::Backend::EnsureDatabaseVersion() {
   // Version check.
   if (!meta_table_.Init(
           db_.get(), kCurrentVersionNumber, kCompatibleVersionNumber)) {
     return false;
   }

   if (meta_table_.GetCompatibleVersionNumber() > kCurrentVersionNumber) {
     LOG(WARNING) << "Server bound cert database is too new.";
     return false;
   }

   int cur_version = meta_table_.GetVersionNumber();
   if (cur_version == 1) {
     sql::Transaction transaction(db_.get());
     if (!transaction.Begin())
       return false;
     if (!db_->Execute(
             "ALTER TABLE origin_bound_certs ADD COLUMN cert_type "
             "INTEGER")) {
       LOG(WARNING) << "Unable to update server bound cert database to "
                    << "version 2.";
       return false;
     }
     // All certs in version 1 database are rsa_sign, which are unsupported.
     // Just discard them all.
     if (!db_->Execute("DELETE from origin_bound_certs")) {
       LOG(WARNING) << "Unable to update server bound cert database to "
                    << "version 2.";
       return false;
     }
     ++cur_version;
     meta_table_.SetVersionNumber(cur_version);
     meta_table_.SetCompatibleVersionNumber(
         std::min(cur_version, kCompatibleVersionNumber));
     transaction.Commit();
   }

   if (cur_version <= 3) {
     sql::Transaction transaction(db_.get());
     if (!transaction.Begin())
       return false;

     if (cur_version == 2) {
       if (!db_->Execute(
               "ALTER TABLE origin_bound_certs ADD COLUMN "
               "expiration_time INTEGER")) {
         LOG(WARNING) << "Unable to update server bound cert database to "
                      << "version 4.";
         return false;
       }
     }

     if (!db_->Execute(
             "ALTER TABLE origin_bound_certs ADD COLUMN "
             "creation_time INTEGER")) {
       LOG(WARNING) << "Unable to update server bound cert database to "
                    << "version 4.";
       return false;
     }

     sql::Statement statement(
         db_->GetUniqueStatement("SELECT origin, cert FROM origin_bound_certs"));
     sql::Statement update_expires_statement(db_->GetUniqueStatement(
         "UPDATE origin_bound_certs SET expiration_time = ? WHERE origin = ?"));
     sql::Statement update_creation_statement(db_->GetUniqueStatement(
         "UPDATE origin_bound_certs SET creation_time = ? WHERE origin = ?"));
     if (!statement.is_valid() || !update_expires_statement.is_valid() ||
         !update_creation_statement.is_valid()) {
       LOG(WARNING) << "Unable to update server bound cert database to "
                    << "version 4.";
       return false;
     }

     while (statement.Step()) {
       std::string origin = statement.ColumnString(0);
       std::string cert_from_db;
       statement.ColumnBlobAsString(1, &cert_from_db);
       // Parse the cert and extract the real value and then update the DB.
       scoped_refptr<X509Certificate> cert(X509Certificate::CreateFromBytes(
           cert_from_db.data(), static_cast<int>(cert_from_db.size())));
       if (cert.get()) {
         if (cur_version == 2) {
           update_expires_statement.Reset(true);
           update_expires_statement.BindInt64(
               0, cert->valid_expiry().ToInternalValue());
           update_expires_statement.BindString(1, origin);
           if (!update_expires_statement.Run()) {
             LOG(WARNING) << "Unable to update server bound cert database to "
                          << "version 4.";
             return false;
           }
         }

         update_creation_statement.Reset(true);
         update_creation_statement.BindInt64(
             0, cert->valid_start().ToInternalValue());
         update_creation_statement.BindString(1, origin);
         if (!update_creation_statement.Run()) {
           LOG(WARNING) << "Unable to update server bound cert database to "
                        << "version 4.";
           return false;
         }
       } else {
         // If there's a cert we can't parse, just leave it.  It'll get replaced
         // with a new one if we ever try to use it.
         LOG(WARNING) << "Error parsing cert for database upgrade for origin "
                      << statement.ColumnString(0);
       }
     }

     cur_version = 4;
     meta_table_.SetVersionNumber(cur_version);
     meta_table_.SetCompatibleVersionNumber(
         std::min(cur_version, kCompatibleVersionNumber));
     transaction.Commit();
   }

   // Put future migration cases here.

   // When the version is too old, we just try to continue anyway, there should
   // not be a released product that makes a database too old for us to handle.
   LOG_IF(WARNING, cur_version < kCurrentVersionNumber)
       << "Server bound cert database version " << cur_version
       << " is too old to handle.";

   return true;
 }

 void SQLiteChannelIDStore::Backend::DatabaseErrorCallback(
     int error,
     sql::Statement* stmt) {
   DCHECK(background_task_runner_->RunsTasksOnCurrentThread());

   if (!sql::IsErrorCatastrophic(error))
     return;

   // TODO(shess): Running KillDatabase() multiple times should be
   // safe.
   if (corruption_detected_)
     return;

   corruption_detected_ = true;

   // TODO(shess): Consider just calling RazeAndClose() immediately.
   // db_ may not be safe to reset at this point, but RazeAndClose()
   // would cause the stack to unwind safely with errors.
   background_task_runner_->PostTask(FROM_HERE,
                                     base::Bind(&Backend::KillDatabase, this));
 }

 void SQLiteChannelIDStore::Backend::KillDatabase() {
   DCHECK(background_task_runner_->RunsTasksOnCurrentThread());

   if (db_) {
     // This Backend will now be in-memory only. In a future run the database
     // will be recreated. Hopefully things go better then!
     bool success = db_->RazeAndClose();
     UMA_HISTOGRAM_BOOLEAN("DomainBoundCerts.KillDatabaseResult", success);
     meta_table_.Reset();
     db_.reset();
   }
 }

 void SQLiteChannelIDStore::Backend::AddChannelID(
     const DefaultChannelIDStore::ChannelID& channel_id) {
   BatchOperation(PendingOperation::CHANNEL_ID_ADD, channel_id);
 }

 void SQLiteChannelIDStore::Backend::DeleteChannelID(
     const DefaultChannelIDStore::ChannelID& channel_id) {
   BatchOperation(PendingOperation::CHANNEL_ID_DELETE, channel_id);
 }

 void SQLiteChannelIDStore::Backend::DeleteAllInList(
     const std::list<std::string>& server_identifiers) {
   if (server_identifiers.empty())
     return;
   // Perform deletion on background task runner.
   background_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(
           &Backend::BackgroundDeleteAllInList, this, server_identifiers));
 }

 void SQLiteChannelIDStore::Backend::BatchOperation(
     PendingOperation::OperationType op,
     const DefaultChannelIDStore::ChannelID& channel_id) {
   // Commit every 30 seconds.
   static const int kCommitIntervalMs = 30 * 1000;
   // Commit right away if we have more than 512 outstanding operations.
   static const size_t kCommitAfterBatchSize = 512;

   // We do a full copy of the cert here, and hopefully just here.
   scoped_ptr<PendingOperation> po(new PendingOperation(op, channel_id));

   PendingOperationsList::size_type num_pending;
   {
     base::AutoLock locked(lock_);
     pending_.push_back(po.release());
     num_pending = ++num_pending_;
   }

   if (num_pending == 1) {
     // We've gotten our first entry for this batch, fire off the timer.
     background_task_runner_->PostDelayedTask(
         FROM_HERE,
         base::Bind(&Backend::Commit, this),
         base::TimeDelta::FromMilliseconds(kCommitIntervalMs));
   } else if (num_pending == kCommitAfterBatchSize) {
     // We've reached a big enough batch, fire off a commit now.
     background_task_runner_->PostTask(FROM_HERE,
                                       base::Bind(&Backend::Commit, this));
   }
 }

 void SQLiteChannelIDStore::Backend::Commit() {
   DCHECK(background_task_runner_->RunsTasksOnCurrentThread());

   PendingOperationsList ops;
   {
     base::AutoLock locked(lock_);
     pending_.swap(ops);
     num_pending_ = 0;
   }

   // Maybe an old timer fired or we are already Close()'ed.
   if (!db_.get() || ops.empty())
     return;

   sql::Statement add_statement(db_->GetCachedStatement(
       SQL_FROM_HERE,
       "INSERT INTO origin_bound_certs (origin, private_key, cert, cert_type, "
       "expiration_time, creation_time) VALUES (?,?,?,?,?,?)"));
   if (!add_statement.is_valid())
     return;

   sql::Statement del_statement(db_->GetCachedStatement(
       SQL_FROM_HERE, "DELETE FROM origin_bound_certs WHERE origin=?"));
   if (!del_statement.is_valid())
     return;

   sql::Transaction transaction(db_.get());
   if (!transaction.Begin())
     return;

   for (PendingOperationsList::iterator it = ops.begin(); it != ops.end();
        ++it) {
     // Free the certs as we commit them to the database.
     scoped_ptr<PendingOperation> po(*it);
     switch (po->op()) {
       case PendingOperation::CHANNEL_ID_ADD: {
         add_statement.Reset(true);
         add_statement.BindString(0, po->channel_id().server_identifier());
         const std::string& private_key = po->channel_id().private_key();
         add_statement.BindBlob(
             1, private_key.data(), static_cast<int>(private_key.size()));
         const std::string& cert = po->channel_id().cert();
         add_statement.BindBlob(2, cert.data(), static_cast<int>(cert.size()));
         add_statement.BindInt(3, CLIENT_CERT_ECDSA_SIGN);
         add_statement.BindInt64(
             4, po->channel_id().expiration_time().ToInternalValue());
         add_statement.BindInt64(
             5, po->channel_id().creation_time().ToInternalValue());
         if (!add_statement.Run())
           NOTREACHED() << "Could not add a server bound cert to the DB.";
         break;
       }
       case PendingOperation::CHANNEL_ID_DELETE:
         del_statement.Reset(true);
         del_statement.BindString(0, po->channel_id().server_identifier());
         if (!del_statement.Run())
           NOTREACHED() << "Could not delete a server bound cert from the DB.";
         break;

       default:
         NOTREACHED();
         break;
     }
   }
   transaction.Commit();
 }

 // Fire off a close message to the background task runner. We could still have a
 // pending commit timer that will be holding a reference on us, but if/when
 // this fires we will already have been cleaned up and it will be ignored.
 void SQLiteChannelIDStore::Backend::Close() {
   // Must close the backend on the background task runner.
   background_task_runner_->PostTask(
       FROM_HERE, base::Bind(&Backend::InternalBackgroundClose, this));
 }

 void SQLiteChannelIDStore::Backend::InternalBackgroundClose() {
   DCHECK(background_task_runner_->RunsTasksOnCurrentThread());
   // Commit any pending operations
   Commit();
   db_.reset();
 }

 void SQLiteChannelIDStore::Backend::BackgroundDeleteAllInList(
     const std::list<std::string>& server_identifiers) {
   DCHECK(background_task_runner_->RunsTasksOnCurrentThread());

   if (!db_.get())
     return;

   sql::Statement del_smt(db_->GetCachedStatement(
       SQL_FROM_HERE, "DELETE FROM origin_bound_certs WHERE origin=?"));
   if (!del_smt.is_valid()) {
     LOG(WARNING) << "Unable to delete channel ids.";
     return;
   }

   sql::Transaction transaction(db_.get());
   if (!transaction.Begin()) {
     LOG(WARNING) << "Unable to delete channel ids.";
     return;
   }

   for (std::list<std::string>::const_iterator it = server_identifiers.begin();
        it != server_identifiers.end();
        ++it) {
     del_smt.Reset(true);
     del_smt.BindString(0, *it);
     if (!del_smt.Run())
       NOTREACHED() << "Could not delete a channel id from the DB.";
   }

   if (!transaction.Commit())
     LOG(WARNING) << "Unable to delete channel ids.";
 }

 void SQLiteChannelIDStore::Backend::SetForceKeepSessionState() {
   base::AutoLock locked(lock_);
   force_keep_session_state_ = true;
 }

 SQLiteChannelIDStore::SQLiteChannelIDStore(
     const base::FilePath& path,
     const scoped_refptr<base::SequencedTaskRunner>& background_task_runner)
     : backend_(new Backend(path, background_task_runner)) {
 }

 void SQLiteChannelIDStore::Load(const LoadedCallback& loaded_callback) {
   backend_->Load(loaded_callback);
 }

 void SQLiteChannelIDStore::AddChannelID(
     const DefaultChannelIDStore::ChannelID& channel_id) {
   backend_->AddChannelID(channel_id);
 }

 void SQLiteChannelIDStore::DeleteChannelID(
     const DefaultChannelIDStore::ChannelID& channel_id) {
   backend_->DeleteChannelID(channel_id);
 }

 void SQLiteChannelIDStore::DeleteAllInList(
     const std::list<std::string>& server_identifiers) {
   backend_->DeleteAllInList(server_identifiers);
 }

 void SQLiteChannelIDStore::SetForceKeepSessionState() {
   backend_->SetForceKeepSessionState();
 }

 SQLiteChannelIDStore::~SQLiteChannelIDStore() {
   backend_->Close();
   // We release our reference to the Backend, though it will probably still have
   // a reference if the background task runner has not run Close() yet.
 }

 }  // namespace net
	// 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.

	#include "net/extras/sqlite/sqlite_channel_id_store.h"

	#include <set>

	#include "base/basictypes.h"
	#include "base/bind.h"
	#include "base/files/file_path.h"
	#include "base/files/file_util.h"
	#include "base/location.h"
	#include "base/logging.h"
	#include "base/memory/scoped_ptr.h"
	#include "base/memory/scoped_vector.h"
	#include "base/metrics/histogram.h"
	#include "base/sequenced_task_runner.h"
	#include "base/strings/string_util.h"
	#include "net/cert/x509_certificate.h"
	#include "net/cookies/cookie_util.h"
	#include "net/ssl/ssl_client_cert_type.h"
	#include "sql/error_delegate_util.h"
	#include "sql/meta_table.h"
	#include "sql/statement.h"
	#include "sql/transaction.h"
	#include "url/gurl.h"

	namespace {

	// Version number of the database.
	const int kCurrentVersionNumber = 4;
	const int kCompatibleVersionNumber = 1;

	// Initializes the certs table, returning true on success.
	bool InitTable(sql::Connection* db) {
	// The table is named "origin_bound_certs" for backwards compatability before
	// we renamed this class to SQLiteChannelIDStore. Likewise, the primary
	// key is "origin", but now can be other things like a plain domain.
	if (!db->DoesTableExist("origin_bound_certs")) {
	if (!db->Execute(
	"CREATE TABLE origin_bound_certs ("
	"origin TEXT NOT NULL UNIQUE PRIMARY KEY,"
	"private_key BLOB NOT NULL,"
	"cert BLOB NOT NULL,"
	"cert_type INTEGER,"
	"expiration_time INTEGER,"
	"creation_time INTEGER)")) {
	return false;
	}
	}

	return true;
	}

	} // namespace

	namespace net {

	// This class is designed to be shared between any calling threads and the
	// background task runner. It batches operations and commits them on a timer.
	class SQLiteChannelIDStore::Backend
	: public base::RefCountedThreadSafe<SQLiteChannelIDStore::Backend> {
	public:
	Backend(
	const base::FilePath& path,
	const scoped_refptr<base::SequencedTaskRunner>& background_task_runner)
	: path_(path),
	num_pending_(0),
	force_keep_session_state_(false),
	background_task_runner_(background_task_runner),
	corruption_detected_(false) {}

	// Creates or loads the SQLite database.
	void Load(const LoadedCallback& loaded_callback);

	// Batch a channel ID addition.
	void AddChannelID(const DefaultChannelIDStore::ChannelID& channel_id);

	// Batch a channel ID deletion.
	void DeleteChannelID(const DefaultChannelIDStore::ChannelID& channel_id);

	// Post background delete of all channel ids for \|server_identifiers\|.
	void DeleteAllInList(const std::list<std::string>& server_identifiers);

	// Commit any pending operations and close the database. This must be called
	// before the object is destructed.
	void Close();

	void SetForceKeepSessionState();

	private:
	friend class base::RefCountedThreadSafe<SQLiteChannelIDStore::Backend>;

	// You should call Close() before destructing this object.
	virtual ~Backend() {
	DCHECK(!db_.get()) << "Close should have already been called.";
	DCHECK_EQ(0u, num_pending_);
	DCHECK(pending_.empty());
	}

	void LoadInBackground(
	ScopedVector<DefaultChannelIDStore::ChannelID>* channel_ids);

	// Database upgrade statements.
	bool EnsureDatabaseVersion();

	class PendingOperation {
	public:
	enum OperationType { CHANNEL_ID_ADD, CHANNEL_ID_DELETE };

	PendingOperation(OperationType op,
	const DefaultChannelIDStore::ChannelID& channel_id)
	: op_(op), channel_id_(channel_id) {}

	OperationType op() const { return op_; }
	const DefaultChannelIDStore::ChannelID& channel_id() const {
	return channel_id_;
	}

	private:
	OperationType op_;
	DefaultChannelIDStore::ChannelID channel_id_;
	};

	private:
	// Batch a channel id operation (add or delete).
	void BatchOperation(PendingOperation::OperationType op,
	const DefaultChannelIDStore::ChannelID& channel_id);
	// Commit our pending operations to the database.
	void Commit();
	// Close() executed on the background task runner.
	void InternalBackgroundClose();

	void BackgroundDeleteAllInList(
	const std::list<std::string>& server_identifiers);

	void DatabaseErrorCallback(int error, sql::Statement* stmt);
	void KillDatabase();

	const base::FilePath path_;
	scoped_ptr<sql::Connection> db_;
	sql::MetaTable meta_table_;

	typedef std::list<PendingOperation*> PendingOperationsList;
	PendingOperationsList pending_;
	PendingOperationsList::size_type num_pending_;
	// True if the persistent store should skip clear on exit rules.
	bool force_keep_session_state_;
	// Guard \|pending_\|, \|num_pending_\| and \|force_keep_session_state_\|.
	base::Lock lock_;

	scoped_refptr<base::SequencedTaskRunner> background_task_runner_;

	// Indicates if the kill-database callback has been scheduled.
	bool corruption_detected_;

	DISALLOW_COPY_AND_ASSIGN(Backend);
	};

	void SQLiteChannelIDStore::Backend::Load(
	const LoadedCallback& loaded_callback) {
	// This function should be called only once per instance.
	DCHECK(!db_.get());
	scoped_ptr<ScopedVector<DefaultChannelIDStore::ChannelID> > channel_ids(
	new ScopedVector<DefaultChannelIDStore::ChannelID>());
	ScopedVector<DefaultChannelIDStore::ChannelID>* channel_ids_ptr =
	channel_ids.get();

	background_task_runner_->PostTaskAndReply(
	FROM_HERE,
	base::Bind(&Backend::LoadInBackground, this, channel_ids_ptr),
	base::Bind(loaded_callback, base::Passed(&channel_ids)));
	}

	void SQLiteChannelIDStore::Backend::LoadInBackground(
	ScopedVector<DefaultChannelIDStore::ChannelID>* channel_ids) {
	DCHECK(background_task_runner_->RunsTasksOnCurrentThread());

	// This method should be called only once per instance.
	DCHECK(!db_.get());

	base::TimeTicks start = base::TimeTicks::Now();

	// Ensure the parent directory for storing certs is created before reading
	// from it.
	const base::FilePath dir = path_.DirName();
	if (!base::PathExists(dir) && !base::CreateDirectory(dir))
	return;

	int64 db_size = 0;
	if (base::GetFileSize(path_, &db_size))
	UMA_HISTOGRAM_COUNTS("DomainBoundCerts.DBSizeInKB", db_size / 1024);

	db_.reset(new sql::Connection);
	db_->set_histogram_tag("DomainBoundCerts");

	// Unretained to avoid a ref loop with db_.
	db_->set_error_callback(
	base::Bind(&SQLiteChannelIDStore::Backend::DatabaseErrorCallback,
	base::Unretained(this)));

	if (!db_->Open(path_)) {
	NOTREACHED() << "Unable to open cert DB.";
	if (corruption_detected_)
	KillDatabase();
	db_.reset();
	return;
	}

	if (!EnsureDatabaseVersion() \|\| !InitTable(db_.get())) {
	NOTREACHED() << "Unable to open cert DB.";
	if (corruption_detected_)
	KillDatabase();
	meta_table_.Reset();
	db_.reset();
	return;
	}

	db_->Preload();

	// Slurp all the certs into the out-vector.
	sql::Statement smt(db_->GetUniqueStatement(
	"SELECT origin, private_key, cert, cert_type, expiration_time, "
	"creation_time FROM origin_bound_certs"));
	if (!smt.is_valid()) {
	if (corruption_detected_)
	KillDatabase();
	meta_table_.Reset();
	db_.reset();
	return;
	}

	while (smt.Step()) {
	SSLClientCertType type = static_cast<SSLClientCertType>(smt.ColumnInt(3));
	if (type != CLIENT_CERT_ECDSA_SIGN)
	continue;
	std::string private_key_from_db, cert_from_db;
	smt.ColumnBlobAsString(1, &private_key_from_db);
	smt.ColumnBlobAsString(2, &cert_from_db);
	scoped_ptr<DefaultChannelIDStore::ChannelID> channel_id(
	new DefaultChannelIDStore::ChannelID(
	smt.ColumnString(0), // origin
	base::Time::FromInternalValue(smt.ColumnInt64(5)),
	base::Time::FromInternalValue(smt.ColumnInt64(4)),
	private_key_from_db,
	cert_from_db));
	channel_ids->push_back(channel_id.release());
	}

	UMA_HISTOGRAM_COUNTS_10000(
	"DomainBoundCerts.DBLoadedCount",
	static_cast<base::HistogramBase::Sample>(channel_ids->size()));
	base::TimeDelta load_time = base::TimeTicks::Now() - start;
	UMA_HISTOGRAM_CUSTOM_TIMES("DomainBoundCerts.DBLoadTime",
	load_time,
	base::TimeDelta::FromMilliseconds(1),
	base::TimeDelta::FromMinutes(1),
	50);
	DVLOG(1) << "loaded " << channel_ids->size() << " in "
	<< load_time.InMilliseconds() << " ms";
	}

	bool SQLiteChannelIDStore::Backend::EnsureDatabaseVersion() {
	// Version check.
	if (!meta_table_.Init(
	db_.get(), kCurrentVersionNumber, kCompatibleVersionNumber)) {
	return false;
	}

	if (meta_table_.GetCompatibleVersionNumber() > kCurrentVersionNumber) {
	LOG(WARNING) << "Server bound cert database is too new.";
	return false;
	}

	int cur_version = meta_table_.GetVersionNumber();
	if (cur_version == 1) {
	sql::Transaction transaction(db_.get());
	if (!transaction.Begin())
	return false;
	if (!db_->Execute(
	"ALTER TABLE origin_bound_certs ADD COLUMN cert_type "
	"INTEGER")) {
	LOG(WARNING) << "Unable to update server bound cert database to "
	<< "version 2.";
	return false;
	}
	// All certs in version 1 database are rsa_sign, which are unsupported.
	// Just discard them all.
	if (!db_->Execute("DELETE from origin_bound_certs")) {
	LOG(WARNING) << "Unable to update server bound cert database to "
	<< "version 2.";
	return false;
	}
	++cur_version;
	meta_table_.SetVersionNumber(cur_version);
	meta_table_.SetCompatibleVersionNumber(
	std::min(cur_version, kCompatibleVersionNumber));
	transaction.Commit();
	}

	if (cur_version <= 3) {
	sql::Transaction transaction(db_.get());
	if (!transaction.Begin())
	return false;

	if (cur_version == 2) {
	if (!db_->Execute(
	"ALTER TABLE origin_bound_certs ADD COLUMN "
	"expiration_time INTEGER")) {
	LOG(WARNING) << "Unable to update server bound cert database to "
	<< "version 4.";
	return false;
	}
	}

	if (!db_->Execute(
	"ALTER TABLE origin_bound_certs ADD COLUMN "
	"creation_time INTEGER")) {
	LOG(WARNING) << "Unable to update server bound cert database to "
	<< "version 4.";
	return false;
	}

	sql::Statement statement(
	db_->GetUniqueStatement("SELECT origin, cert FROM origin_bound_certs"));
	sql::Statement update_expires_statement(db_->GetUniqueStatement(
	"UPDATE origin_bound_certs SET expiration_time = ? WHERE origin = ?"));
	sql::Statement update_creation_statement(db_->GetUniqueStatement(
	"UPDATE origin_bound_certs SET creation_time = ? WHERE origin = ?"));
	if (!statement.is_valid() \|\| !update_expires_statement.is_valid() \|\|
	!update_creation_statement.is_valid()) {
	LOG(WARNING) << "Unable to update server bound cert database to "
	<< "version 4.";
	return false;
	}

	while (statement.Step()) {
	std::string origin = statement.ColumnString(0);
	std::string cert_from_db;
	statement.ColumnBlobAsString(1, &cert_from_db);
	// Parse the cert and extract the real value and then update the DB.
	scoped_refptr<X509Certificate> cert(X509Certificate::CreateFromBytes(
	cert_from_db.data(), static_cast<int>(cert_from_db.size())));
	if (cert.get()) {
	if (cur_version == 2) {
	update_expires_statement.Reset(true);
	update_expires_statement.BindInt64(
	0, cert->valid_expiry().ToInternalValue());
	update_expires_statement.BindString(1, origin);
	if (!update_expires_statement.Run()) {
	LOG(WARNING) << "Unable to update server bound cert database to "
	<< "version 4.";
	return false;
	}
	}

	update_creation_statement.Reset(true);
	update_creation_statement.BindInt64(
	0, cert->valid_start().ToInternalValue());
	update_creation_statement.BindString(1, origin);
	if (!update_creation_statement.Run()) {
	LOG(WARNING) << "Unable to update server bound cert database to "
	<< "version 4.";
	return false;
	}
	} else {
	// If there's a cert we can't parse, just leave it. It'll get replaced
	// with a new one if we ever try to use it.
	LOG(WARNING) << "Error parsing cert for database upgrade for origin "
	<< statement.ColumnString(0);
	}
	}

	cur_version = 4;
	meta_table_.SetVersionNumber(cur_version);
	meta_table_.SetCompatibleVersionNumber(
	std::min(cur_version, kCompatibleVersionNumber));
	transaction.Commit();
	}

	// Put future migration cases here.

	// When the version is too old, we just try to continue anyway, there should
	// not be a released product that makes a database too old for us to handle.
	LOG_IF(WARNING, cur_version < kCurrentVersionNumber)
	<< "Server bound cert database version " << cur_version
	<< " is too old to handle.";

	return true;
	}

	void SQLiteChannelIDStore::Backend::DatabaseErrorCallback(
	int error,
	sql::Statement* stmt) {
	DCHECK(background_task_runner_->RunsTasksOnCurrentThread());

	if (!sql::IsErrorCatastrophic(error))
	return;

	// TODO(shess): Running KillDatabase() multiple times should be
	// safe.
	if (corruption_detected_)
	return;

	corruption_detected_ = true;

	// TODO(shess): Consider just calling RazeAndClose() immediately.
	// db_ may not be safe to reset at this point, but RazeAndClose()
	// would cause the stack to unwind safely with errors.
	background_task_runner_->PostTask(FROM_HERE,
	base::Bind(&Backend::KillDatabase, this));
	}

	void SQLiteChannelIDStore::Backend::KillDatabase() {
	DCHECK(background_task_runner_->RunsTasksOnCurrentThread());

	if (db_) {
	// This Backend will now be in-memory only. In a future run the database
	// will be recreated. Hopefully things go better then!
	bool success = db_->RazeAndClose();
	UMA_HISTOGRAM_BOOLEAN("DomainBoundCerts.KillDatabaseResult", success);
	meta_table_.Reset();
	db_.reset();
	}
	}

	void SQLiteChannelIDStore::Backend::AddChannelID(
	const DefaultChannelIDStore::ChannelID& channel_id) {
	BatchOperation(PendingOperation::CHANNEL_ID_ADD, channel_id);
	}

	void SQLiteChannelIDStore::Backend::DeleteChannelID(
	const DefaultChannelIDStore::ChannelID& channel_id) {
	BatchOperation(PendingOperation::CHANNEL_ID_DELETE, channel_id);
	}

	void SQLiteChannelIDStore::Backend::DeleteAllInList(
	const std::list<std::string>& server_identifiers) {
	if (server_identifiers.empty())
	return;
	// Perform deletion on background task runner.
	background_task_runner_->PostTask(
	FROM_HERE,
	base::Bind(
	&Backend::BackgroundDeleteAllInList, this, server_identifiers));
	}

	void SQLiteChannelIDStore::Backend::BatchOperation(
	PendingOperation::OperationType op,
	const DefaultChannelIDStore::ChannelID& channel_id) {
	// Commit every 30 seconds.
	static const int kCommitIntervalMs = 30 * 1000;
	// Commit right away if we have more than 512 outstanding operations.
	static const size_t kCommitAfterBatchSize = 512;

	// We do a full copy of the cert here, and hopefully just here.
	scoped_ptr<PendingOperation> po(new PendingOperation(op, channel_id));

	PendingOperationsList::size_type num_pending;
	{
	base::AutoLock locked(lock_);
	pending_.push_back(po.release());
	num_pending = ++num_pending_;
	}

	if (num_pending == 1) {
	// We've gotten our first entry for this batch, fire off the timer.
	background_task_runner_->PostDelayedTask(
	FROM_HERE,
	base::Bind(&Backend::Commit, this),
	base::TimeDelta::FromMilliseconds(kCommitIntervalMs));
	} else if (num_pending == kCommitAfterBatchSize) {
	// We've reached a big enough batch, fire off a commit now.
	background_task_runner_->PostTask(FROM_HERE,
	base::Bind(&Backend::Commit, this));
	}
	}

	void SQLiteChannelIDStore::Backend::Commit() {
	DCHECK(background_task_runner_->RunsTasksOnCurrentThread());

	PendingOperationsList ops;
	{
	base::AutoLock locked(lock_);
	pending_.swap(ops);
	num_pending_ = 0;
	}

	// Maybe an old timer fired or we are already Close()'ed.
	if (!db_.get() \|\| ops.empty())
	return;

	sql::Statement add_statement(db_->GetCachedStatement(
	SQL_FROM_HERE,
	"INSERT INTO origin_bound_certs (origin, private_key, cert, cert_type, "
	"expiration_time, creation_time) VALUES (?,?,?,?,?,?)"));
	if (!add_statement.is_valid())
	return;

	sql::Statement del_statement(db_->GetCachedStatement(
	SQL_FROM_HERE, "DELETE FROM origin_bound_certs WHERE origin=?"));
	if (!del_statement.is_valid())
	return;

	sql::Transaction transaction(db_.get());
	if (!transaction.Begin())
	return;

	for (PendingOperationsList::iterator it = ops.begin(); it != ops.end();
	++it) {
	// Free the certs as we commit them to the database.
	scoped_ptr<PendingOperation> po(*it);
	switch (po->op()) {
	case PendingOperation::CHANNEL_ID_ADD: {
	add_statement.Reset(true);
	add_statement.BindString(0, po->channel_id().server_identifier());
	const std::string& private_key = po->channel_id().private_key();
	add_statement.BindBlob(
	1, private_key.data(), static_cast<int>(private_key.size()));
	const std::string& cert = po->channel_id().cert();
	add_statement.BindBlob(2, cert.data(), static_cast<int>(cert.size()));
	add_statement.BindInt(3, CLIENT_CERT_ECDSA_SIGN);
	add_statement.BindInt64(
	4, po->channel_id().expiration_time().ToInternalValue());
	add_statement.BindInt64(
	5, po->channel_id().creation_time().ToInternalValue());
	if (!add_statement.Run())
	NOTREACHED() << "Could not add a server bound cert to the DB.";
	break;
	}
	case PendingOperation::CHANNEL_ID_DELETE:
	del_statement.Reset(true);
	del_statement.BindString(0, po->channel_id().server_identifier());
	if (!del_statement.Run())
	NOTREACHED() << "Could not delete a server bound cert from the DB.";
	break;

	default:
	NOTREACHED();
	break;
	}
	}
	transaction.Commit();
	}

	// Fire off a close message to the background task runner. We could still have a
	// pending commit timer that will be holding a reference on us, but if/when
	// this fires we will already have been cleaned up and it will be ignored.
	void SQLiteChannelIDStore::Backend::Close() {
	// Must close the backend on the background task runner.
	background_task_runner_->PostTask(
	FROM_HERE, base::Bind(&Backend::InternalBackgroundClose, this));
	}

	void SQLiteChannelIDStore::Backend::InternalBackgroundClose() {
	DCHECK(background_task_runner_->RunsTasksOnCurrentThread());
	// Commit any pending operations
	Commit();
	db_.reset();
	}

	void SQLiteChannelIDStore::Backend::BackgroundDeleteAllInList(
	const std::list<std::string>& server_identifiers) {
	DCHECK(background_task_runner_->RunsTasksOnCurrentThread());

	if (!db_.get())
	return;

	sql::Statement del_smt(db_->GetCachedStatement(
	SQL_FROM_HERE, "DELETE FROM origin_bound_certs WHERE origin=?"));
	if (!del_smt.is_valid()) {
	LOG(WARNING) << "Unable to delete channel ids.";
	return;
	}

	sql::Transaction transaction(db_.get());
	if (!transaction.Begin()) {
	LOG(WARNING) << "Unable to delete channel ids.";
	return;
	}

	for (std::list<std::string>::const_iterator it = server_identifiers.begin();
	it != server_identifiers.end();
	++it) {
	del_smt.Reset(true);
	del_smt.BindString(0, *it);
	if (!del_smt.Run())
	NOTREACHED() << "Could not delete a channel id from the DB.";
	}

	if (!transaction.Commit())
	LOG(WARNING) << "Unable to delete channel ids.";
	}

	void SQLiteChannelIDStore::Backend::SetForceKeepSessionState() {
	base::AutoLock locked(lock_);
	force_keep_session_state_ = true;
	}

	SQLiteChannelIDStore::SQLiteChannelIDStore(
	const base::FilePath& path,
	const scoped_refptr<base::SequencedTaskRunner>& background_task_runner)
	: backend_(new Backend(path, background_task_runner)) {
	}

	void SQLiteChannelIDStore::Load(const LoadedCallback& loaded_callback) {
	backend_->Load(loaded_callback);
	}

	void SQLiteChannelIDStore::AddChannelID(
	const DefaultChannelIDStore::ChannelID& channel_id) {
	backend_->AddChannelID(channel_id);
	}

	void SQLiteChannelIDStore::DeleteChannelID(
	const DefaultChannelIDStore::ChannelID& channel_id) {
	backend_->DeleteChannelID(channel_id);
	}

	void SQLiteChannelIDStore::DeleteAllInList(
	const std::list<std::string>& server_identifiers) {
	backend_->DeleteAllInList(server_identifiers);
	}

	void SQLiteChannelIDStore::SetForceKeepSessionState() {
	backend_->SetForceKeepSessionState();
	}

	SQLiteChannelIDStore::~SQLiteChannelIDStore() {
	backend_->Close();
	// We release our reference to the Backend, though it will probably still have
	// a reference if the background task runner has not run Close() yet.
	}

	} // namespace net