sync/engine/syncer_proto_util.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "sync/engine/syncer_proto_util.h"
   6
   7 #include "base/format_macros.h"
   8 #include "base/strings/stringprintf.h"
   9 #include "google_apis/google_api_keys.h"
  10 #include "sync/engine/net/server_connection_manager.h"
  11 #include "sync/engine/syncer.h"
  12 #include "sync/engine/syncer_types.h"
  13 #include "sync/engine/traffic_logger.h"
  14 #include "sync/internal_api/public/base/model_type.h"
  15 #include "sync/protocol/sync_enums.pb.h"
  16 #include "sync/protocol/sync_protocol_error.h"
  17 #include "sync/sessions/sync_session.h"
  18 #include "sync/syncable/directory.h"
  19 #include "sync/syncable/entry.h"
  20 #include "sync/syncable/syncable-inl.h"
  21 #include "sync/syncable/syncable_proto_util.h"
  22 #include "sync/util/time.h"
  23
  24 using std::string;
  25 using std::stringstream;
  26 using sync_pb::ClientToServerMessage;
  27 using sync_pb::ClientToServerResponse;
  28
  29 namespace syncer {
  30
  31 using sessions::SyncSession;
  32 using syncable::BASE_VERSION;
  33 using syncable::CTIME;
  34 using syncable::ID;
  35 using syncable::IS_DEL;
  36 using syncable::IS_DIR;
  37 using syncable::IS_UNSYNCED;
  38 using syncable::MTIME;
  39 using syncable::PARENT_ID;
  40
  41 namespace {
  42
  43 // Time to backoff syncing after receiving a throttled response.
  44 const int kSyncDelayAfterThrottled = 2 * 60 * 60;  // 2 hours
  45
  46 void LogResponseProfilingData(const ClientToServerResponse& response) {
  47   if (response.has_profiling_data()) {
  48     stringstream response_trace;
  49     response_trace << "Server response trace:";
  50
  51     if (response.profiling_data().has_user_lookup_time()) {
  52       response_trace << " user lookup: "
  53                      << response.profiling_data().user_lookup_time() << "ms";
  54     }
  55
  56     if (response.profiling_data().has_meta_data_write_time()) {
  57       response_trace << " meta write: "
  58                      << response.profiling_data().meta_data_write_time()
  59                      << "ms";
  60     }
  61
  62     if (response.profiling_data().has_meta_data_read_time()) {
  63       response_trace << " meta read: "
  64                      << response.profiling_data().meta_data_read_time() << "ms";
  65     }
  66
  67     if (response.profiling_data().has_file_data_write_time()) {
  68       response_trace << " file write: "
  69                      << response.profiling_data().file_data_write_time()
  70                      << "ms";
  71     }
  72
  73     if (response.profiling_data().has_file_data_read_time()) {
  74       response_trace << " file read: "
  75                      << response.profiling_data().file_data_read_time() << "ms";
  76     }
  77
  78     if (response.profiling_data().has_total_request_time()) {
  79       response_trace << " total time: "
  80                      << response.profiling_data().total_request_time() << "ms";
  81     }
  82     DVLOG(1) << response_trace.str();
  83   }
  84 }
  85
  86 SyncerError ServerConnectionErrorAsSyncerError(
  87     const HttpResponse::ServerConnectionCode server_status) {
  88   switch (server_status) {
  89     case HttpResponse::CONNECTION_UNAVAILABLE:
  90       return NETWORK_CONNECTION_UNAVAILABLE;
  91     case HttpResponse::IO_ERROR:
  92       return NETWORK_IO_ERROR;
  93     case HttpResponse::SYNC_SERVER_ERROR:
  94       // FIXME what does this mean?
  95       return SYNC_SERVER_ERROR;
  96     case HttpResponse::SYNC_AUTH_ERROR:
  97       return SYNC_AUTH_ERROR;
  98     case HttpResponse::RETRY:
  99       return SERVER_RETURN_TRANSIENT_ERROR;
 100     case HttpResponse::SERVER_CONNECTION_OK:
 101     case HttpResponse::NONE:
 102     default:
 103       NOTREACHED();
 104       return UNSET;
 105   }
 106 }
 107
 108 SyncProtocolErrorType ConvertSyncProtocolErrorTypePBToLocalType(
 109     const sync_pb::SyncEnums::ErrorType& error_type) {
 110   switch (error_type) {
 111     case sync_pb::SyncEnums::SUCCESS:
 112       return SYNC_SUCCESS;
 113     case sync_pb::SyncEnums::NOT_MY_BIRTHDAY:
 114       return NOT_MY_BIRTHDAY;
 115     case sync_pb::SyncEnums::THROTTLED:
 116       return THROTTLED;
 117     case sync_pb::SyncEnums::CLEAR_PENDING:
 118       return CLEAR_PENDING;
 119     case sync_pb::SyncEnums::TRANSIENT_ERROR:
 120       return TRANSIENT_ERROR;
 121     case sync_pb::SyncEnums::MIGRATION_DONE:
 122       return MIGRATION_DONE;
 123     case sync_pb::SyncEnums::DISABLED_BY_ADMIN:
 124       return DISABLED_BY_ADMIN;
 125     case sync_pb::SyncEnums::USER_ROLLBACK:
 126       return USER_ROLLBACK;
 127     case sync_pb::SyncEnums::UNKNOWN:
 128       return UNKNOWN_ERROR;
 129     case sync_pb::SyncEnums::USER_NOT_ACTIVATED:
 130     case sync_pb::SyncEnums::AUTH_INVALID:
 131     case sync_pb::SyncEnums::ACCESS_DENIED:
 132       return INVALID_CREDENTIAL;
 133     default:
 134       NOTREACHED();
 135       return UNKNOWN_ERROR;
 136   }
 137 }
 138
 139 ClientAction ConvertClientActionPBToLocalClientAction(
 140     const sync_pb::SyncEnums::Action& action) {
 141   switch (action) {
 142     case sync_pb::SyncEnums::UPGRADE_CLIENT:
 143       return UPGRADE_CLIENT;
 144     case sync_pb::SyncEnums::CLEAR_USER_DATA_AND_RESYNC:
 145       return CLEAR_USER_DATA_AND_RESYNC;
 146     case sync_pb::SyncEnums::ENABLE_SYNC_ON_ACCOUNT:
 147       return ENABLE_SYNC_ON_ACCOUNT;
 148     case sync_pb::SyncEnums::STOP_AND_RESTART_SYNC:
 149       return STOP_AND_RESTART_SYNC;
 150     case sync_pb::SyncEnums::DISABLE_SYNC_ON_CLIENT:
 151       return DISABLE_SYNC_ON_CLIENT;
 152     case sync_pb::SyncEnums::UNKNOWN_ACTION:
 153       return UNKNOWN_ACTION;
 154     default:
 155       NOTREACHED();
 156       return UNKNOWN_ACTION;
 157   }
 158 }
 159
 160 }  // namespace
 161
 162 ModelTypeSet GetTypesToMigrate(const ClientToServerResponse& response) {
 163   ModelTypeSet to_migrate;
 164   for (int i = 0; i < response.migrated_data_type_id_size(); i++) {
 165     int field_number = response.migrated_data_type_id(i);
 166     ModelType model_type = GetModelTypeFromSpecificsFieldNumber(field_number);
 167     if (!IsRealDataType(model_type)) {
 168       DLOG(WARNING) << "Unknown field number " << field_number;
 169       continue;
 170     }
 171     to_migrate.Put(model_type);
 172   }
 173   return to_migrate;
 174 }
 175
 176 SyncProtocolError ConvertErrorPBToLocalType(
 177     const sync_pb::ClientToServerResponse_Error& error) {
 178   SyncProtocolError sync_protocol_error;
 179   sync_protocol_error.error_type = ConvertSyncProtocolErrorTypePBToLocalType(
 180       error.error_type());
 181   sync_protocol_error.error_description = error.error_description();
 182   sync_protocol_error.url = error.url();
 183   sync_protocol_error.action = ConvertClientActionPBToLocalClientAction(
 184       error.action());
 185
 186   if (error.error_data_type_ids_size() > 0) {
 187     // THROTTLED is currently the only error code that uses |error_data_types|.
 188     DCHECK_EQ(error.error_type(), sync_pb::SyncEnums::THROTTLED);
 189     for (int i = 0; i < error.error_data_type_ids_size(); ++i) {
 190       int field_number = error.error_data_type_ids(i);
 191       ModelType model_type =
 192           GetModelTypeFromSpecificsFieldNumber(field_number);
 193       if (!IsRealDataType(model_type)) {
 194         DLOG(WARNING) << "Unknown field number " << field_number;
 195         continue;
 196       }
 197       sync_protocol_error.error_data_types.Put(model_type);
 198     }
 199   }
 200
 201   return sync_protocol_error;
 202 }
 203
 204 // static
 205 bool SyncerProtoUtil::VerifyResponseBirthday(
 206     const ClientToServerResponse& response,
 207     syncable::Directory* dir) {
 208
 209   std::string local_birthday = dir->store_birthday();
 210
 211   if (local_birthday.empty()) {
 212     if (!response.has_store_birthday()) {
 213       LOG(WARNING) << "Expected a birthday on first sync.";
 214       return false;
 215     }
 216
 217     DVLOG(1) << "New store birthday: " << response.store_birthday();
 218     dir->set_store_birthday(response.store_birthday());
 219     return true;
 220   }
 221
 222   // Error situation, but we're not stuck.
 223   if (!response.has_store_birthday()) {
 224     LOG(WARNING) << "No birthday in server response?";
 225     return true;
 226   }
 227
 228   if (response.store_birthday() != local_birthday) {
 229     LOG(WARNING) << "Birthday changed, showing syncer stuck";
 230     return false;
 231   }
 232
 233   return true;
 234 }
 235
 236 // static
 237 bool SyncerProtoUtil::IsSyncDisabledByAdmin(
 238     const sync_pb::ClientToServerResponse& response) {
 239   return (response.has_error_code() &&
 240           response.error_code() == sync_pb::SyncEnums::DISABLED_BY_ADMIN);
 241 }
 242
 243 // static
 244 void SyncerProtoUtil::AddRequestBirthday(syncable::Directory* dir,
 245                                          ClientToServerMessage* msg) {
 246   if (!dir->store_birthday().empty())
 247     msg->set_store_birthday(dir->store_birthday());
 248 }
 249
 250 // static
 251 void SyncerProtoUtil::AddBagOfChips(syncable::Directory* dir,
 252                                     ClientToServerMessage* msg) {
 253   msg->mutable_bag_of_chips()->ParseFromString(dir->bag_of_chips());
 254 }
 255
 256 // static
 257 void SyncerProtoUtil::SetProtocolVersion(ClientToServerMessage* msg) {
 258   const int current_version =
 259       ClientToServerMessage::default_instance().protocol_version();
 260   msg->set_protocol_version(current_version);
 261 }
 262
 263 // static
 264 bool SyncerProtoUtil::PostAndProcessHeaders(ServerConnectionManager* scm,
 265                                             sessions::SyncSession* session,
 266                                             const ClientToServerMessage& msg,
 267                                             ClientToServerResponse* response) {
 268   ServerConnectionManager::PostBufferParams params;
 269   DCHECK(msg.has_protocol_version());
 270   DCHECK_EQ(msg.protocol_version(),
 271             ClientToServerMessage::default_instance().protocol_version());
 272   msg.SerializeToString(&params.buffer_in);
 273
 274   ScopedServerStatusWatcher server_status_watcher(scm, &params.response);
 275   // Fills in params.buffer_out and params.response.
 276   if (!scm->PostBufferWithCachedAuth(&params, &server_status_watcher)) {
 277     LOG(WARNING) << "Error posting from syncer:" << params.response;
 278     return false;
 279   }
 280
 281   if (response->ParseFromString(params.buffer_out)) {
 282     // TODO(tim): This is an egregious layering violation (bug 35060).
 283     switch (response->error_code()) {
 284       case sync_pb::SyncEnums::ACCESS_DENIED:
 285       case sync_pb::SyncEnums::AUTH_INVALID:
 286       case sync_pb::SyncEnums::USER_NOT_ACTIVATED:
 287         // Fires on ScopedServerStatusWatcher
 288         params.response.server_status = HttpResponse::SYNC_AUTH_ERROR;
 289         return false;
 290       default:
 291         return true;
 292     }
 293   }
 294
 295   return false;
 296 }
 297
 298 base::TimeDelta SyncerProtoUtil::GetThrottleDelay(
 299     const ClientToServerResponse& response) {
 300   base::TimeDelta throttle_delay =
 301       base::TimeDelta::FromSeconds(kSyncDelayAfterThrottled);
 302   if (response.has_client_command()) {
 303     const sync_pb::ClientCommand& command = response.client_command();
 304     if (command.has_throttle_delay_seconds()) {
 305       throttle_delay =
 306           base::TimeDelta::FromSeconds(command.throttle_delay_seconds());
 307     }
 308   }
 309   return throttle_delay;
 310 }
 311
 312 namespace {
 313
 314 // Helper function for an assertion in PostClientToServerMessage.
 315 bool IsVeryFirstGetUpdates(const ClientToServerMessage& message) {
 316   if (!message.has_get_updates())
 317     return false;
 318   DCHECK_LT(0, message.get_updates().from_progress_marker_size());
 319   for (int i = 0; i < message.get_updates().from_progress_marker_size(); ++i) {
 320     if (!message.get_updates().from_progress_marker(i).token().empty())
 321       return false;
 322   }
 323   return true;
 324 }
 325
 326 // TODO(lipalani) : Rename these function names as per the CR for issue 7740067.
 327 SyncProtocolError ConvertLegacyErrorCodeToNewError(
 328     const sync_pb::SyncEnums::ErrorType& error_type) {
 329   SyncProtocolError error;
 330   error.error_type = ConvertSyncProtocolErrorTypePBToLocalType(error_type);
 331   if (error_type == sync_pb::SyncEnums::CLEAR_PENDING ||
 332       error_type == sync_pb::SyncEnums::NOT_MY_BIRTHDAY) {
 333     error.action = DISABLE_SYNC_ON_CLIENT;
 334   } else if (error_type == sync_pb::SyncEnums::DISABLED_BY_ADMIN) {
 335     error.action = STOP_SYNC_FOR_DISABLED_ACCOUNT;
 336   } else if (error_type == sync_pb::SyncEnums::USER_ROLLBACK) {
 337     error.action = DISABLE_SYNC_AND_ROLLBACK;
 338   } // There is no other action we can compute for legacy server.
 339   return error;
 340 }
 341
 342 }  // namespace
 343
 344 // static
 345 SyncerError SyncerProtoUtil::PostClientToServerMessage(
 346     ClientToServerMessage* msg,
 347     ClientToServerResponse* response,
 348     SyncSession* session) {
 349   CHECK(response);
 350   DCHECK(!msg->get_updates().has_from_timestamp());  // Deprecated.
 351   DCHECK(!msg->get_updates().has_requested_types());  // Deprecated.
 352
 353   // Add must-have fields.
 354   SetProtocolVersion(msg);
 355   AddRequestBirthday(session->context()->directory(), msg);
 356   DCHECK(msg->has_store_birthday() || IsVeryFirstGetUpdates(*msg));
 357   AddBagOfChips(session->context()->directory(), msg);
 358   msg->set_api_key(google_apis::GetAPIKey());
 359   msg->mutable_client_status()->CopyFrom(session->context()->client_status());
 360   msg->set_invalidator_client_id(session->context()->invalidator_client_id());
 361
 362   syncable::Directory* dir = session->context()->directory();
 363
 364   LogClientToServerMessage(*msg);
 365   if (!PostAndProcessHeaders(session->context()->connection_manager(), session,
 366                              *msg, response)) {
 367     // There was an error establishing communication with the server.
 368     // We can not proceed beyond this point.
 369     const HttpResponse::ServerConnectionCode server_status =
 370         session->context()->connection_manager()->server_status();
 371
 372     DCHECK_NE(server_status, HttpResponse::NONE);
 373     DCHECK_NE(server_status, HttpResponse::SERVER_CONNECTION_OK);
 374
 375     return ServerConnectionErrorAsSyncerError(server_status);
 376   }
 377   LogClientToServerResponse(*response);
 378
 379   // Persist a bag of chips if it has been sent by the server.
 380   PersistBagOfChips(dir, *response);
 381
 382   SyncProtocolError sync_protocol_error;
 383
 384   // The DISABLED_BY_ADMIN error overrides other errors sent by the server.
 385   if (IsSyncDisabledByAdmin(*response)) {
 386     sync_protocol_error.error_type = DISABLED_BY_ADMIN;
 387     sync_protocol_error.action = STOP_SYNC_FOR_DISABLED_ACCOUNT;
 388   } else if (!VerifyResponseBirthday(*response, dir)) {
 389     // If sync isn't disabled, first check for a birthday mismatch error.
 390     sync_protocol_error.error_type = NOT_MY_BIRTHDAY;
 391     sync_protocol_error.action = DISABLE_SYNC_ON_CLIENT;
 392   } else if (response->has_error()) {
 393     // This is a new server. Just get the error from the protocol.
 394     sync_protocol_error = ConvertErrorPBToLocalType(response->error());
 395   } else {
 396     // Legacy server implementation. Compute the error based on |error_code|.
 397     sync_protocol_error = ConvertLegacyErrorCodeToNewError(
 398         response->error_code());
 399   }
 400
 401   // Inform the delegate of the error we got.
 402   session->delegate()->OnSyncProtocolError(sync_protocol_error);
 403
 404   // Update our state for any other commands we've received.
 405   if (response->has_client_command()) {
 406     const sync_pb::ClientCommand& command = response->client_command();
 407     if (command.has_max_commit_batch_size()) {
 408       session->context()->set_max_commit_batch_size(
 409           command.max_commit_batch_size());
 410     }
 411
 412     if (command.has_set_sync_long_poll_interval()) {
 413       session->delegate()->OnReceivedLongPollIntervalUpdate(
 414           base::TimeDelta::FromSeconds(command.set_sync_long_poll_interval()));
 415     }
 416
 417     if (command.has_set_sync_poll_interval()) {
 418       session->delegate()->OnReceivedShortPollIntervalUpdate(
 419           base::TimeDelta::FromSeconds(command.set_sync_poll_interval()));
 420     }
 421
 422     if (command.has_sessions_commit_delay_seconds()) {
 423       session->delegate()->OnReceivedSessionsCommitDelay(
 424           base::TimeDelta::FromSeconds(
 425               command.sessions_commit_delay_seconds()));
 426     }
 427
 428     if (command.has_client_invalidation_hint_buffer_size()) {
 429       session->delegate()->OnReceivedClientInvalidationHintBufferSize(
 430           command.client_invalidation_hint_buffer_size());
 431     }
 432
 433     if (command.has_gu_retry_delay_seconds()) {
 434       session->delegate()->OnReceivedGuRetryDelay(
 435           base::TimeDelta::FromSeconds(command.gu_retry_delay_seconds()));
 436     }
 437   }
 438
 439   // Now do any special handling for the error type and decide on the return
 440   // value.
 441   switch (sync_protocol_error.error_type) {
 442     case UNKNOWN_ERROR:
 443       LOG(WARNING) << "Sync protocol out-of-date. The server is using a more "
 444                    << "recent version.";
 445       return SERVER_RETURN_UNKNOWN_ERROR;
 446     case SYNC_SUCCESS:
 447       LogResponseProfilingData(*response);
 448       return SYNCER_OK;
 449     case THROTTLED:
 450       if (sync_protocol_error.error_data_types.Empty()) {
 451         DLOG(WARNING) << "Client fully throttled by syncer.";
 452         session->delegate()->OnThrottled(GetThrottleDelay(*response));
 453       } else {
 454         DLOG(WARNING) << "Some types throttled by syncer.";
 455         session->delegate()->OnTypesThrottled(
 456             sync_protocol_error.error_data_types,
 457             GetThrottleDelay(*response));
 458       }
 459       return SERVER_RETURN_THROTTLED;
 460     case TRANSIENT_ERROR:
 461       return SERVER_RETURN_TRANSIENT_ERROR;
 462     case MIGRATION_DONE:
 463       LOG_IF(ERROR, 0 >= response->migrated_data_type_id_size())
 464           << "MIGRATION_DONE but no types specified.";
 465       session->delegate()->OnReceivedMigrationRequest(
 466           GetTypesToMigrate(*response));
 467       return SERVER_RETURN_MIGRATION_DONE;
 468     case CLEAR_PENDING:
 469       return SERVER_RETURN_CLEAR_PENDING;
 470     case NOT_MY_BIRTHDAY:
 471       return SERVER_RETURN_NOT_MY_BIRTHDAY;
 472     case DISABLED_BY_ADMIN:
 473       return SERVER_RETURN_DISABLED_BY_ADMIN;
 474     case USER_ROLLBACK:
 475       return SERVER_RETURN_USER_ROLLBACK;
 476     default:
 477       NOTREACHED();
 478       return UNSET;
 479   }
 480 }
 481
 482 // static
 483 bool SyncerProtoUtil::ShouldMaintainPosition(
 484     const sync_pb::SyncEntity& sync_entity) {
 485   // Maintain positions for bookmarks that are not server-defined top-level
 486   // folders.
 487   return GetModelType(sync_entity) == BOOKMARKS
 488       && !(sync_entity.folder() &&
 489            !sync_entity.server_defined_unique_tag().empty());
 490 }
 491
 492 // static
 493 void SyncerProtoUtil::CopyProtoBytesIntoBlob(const std::string& proto_bytes,
 494                                              syncable::Blob* blob) {
 495   syncable::Blob proto_blob(proto_bytes.begin(), proto_bytes.end());
 496   blob->swap(proto_blob);
 497 }
 498
 499 // static
 500 bool SyncerProtoUtil::ProtoBytesEqualsBlob(const std::string& proto_bytes,
 501                                            const syncable::Blob& blob) {
 502   if (proto_bytes.size() != blob.size())
 503     return false;
 504   return std::equal(proto_bytes.begin(), proto_bytes.end(), blob.begin());
 505 }
 506
 507 // static
 508 void SyncerProtoUtil::CopyBlobIntoProtoBytes(const syncable::Blob& blob,
 509                                              std::string* proto_bytes) {
 510   std::string blob_string(blob.begin(), blob.end());
 511   proto_bytes->swap(blob_string);
 512 }
 513
 514 // static
 515 const std::string& SyncerProtoUtil::NameFromSyncEntity(
 516     const sync_pb::SyncEntity& entry) {
 517   if (entry.has_non_unique_name())
 518     return entry.non_unique_name();
 519   return entry.name();
 520 }
 521
 522 // static
 523 const std::string& SyncerProtoUtil::NameFromCommitEntryResponse(
 524     const sync_pb::CommitResponse_EntryResponse& entry) {
 525   if (entry.has_non_unique_name())
 526     return entry.non_unique_name();
 527   return entry.name();
 528 }
 529
 530 // static
 531 void SyncerProtoUtil::PersistBagOfChips(syncable::Directory* dir,
 532     const sync_pb::ClientToServerResponse& response) {
 533   if (!response.has_new_bag_of_chips())
 534     return;
 535   std::string bag_of_chips;
 536   if (response.new_bag_of_chips().SerializeToString(&bag_of_chips))
 537     dir->set_bag_of_chips(bag_of_chips);
 538 }
 539
 540 std::string SyncerProtoUtil::SyncEntityDebugString(
 541     const sync_pb::SyncEntity& entry) {
 542   const std::string& mtime_str =
 543       GetTimeDebugString(ProtoTimeToTime(entry.mtime()));
 544   const std::string& ctime_str =
 545       GetTimeDebugString(ProtoTimeToTime(entry.ctime()));
 546   return base::StringPrintf(
 547       "id: %s, parent_id: %s, "
 548       "version: %" PRId64"d, "
 549       "mtime: %" PRId64"d (%s), "
 550       "ctime: %" PRId64"d (%s), "
 551       "name: %s, sync_timestamp: %" PRId64"d, "
 552       "%s ",
 553       entry.id_string().c_str(),
 554       entry.parent_id_string().c_str(),
 555       entry.version(),
 556       entry.mtime(), mtime_str.c_str(),
 557       entry.ctime(), ctime_str.c_str(),
 558       entry.name().c_str(), entry.sync_timestamp(),
 559       entry.deleted() ? "deleted, ":"");
 560 }
 561
 562 namespace {
 563 std::string GetUpdatesResponseString(
 564     const sync_pb::GetUpdatesResponse& response) {
 565   std::string output;
 566   output.append("GetUpdatesResponse:\n");
 567   for (int i = 0; i < response.entries_size(); i++) {
 568     output.append(SyncerProtoUtil::SyncEntityDebugString(response.entries(i)));
 569     output.append("\n");
 570   }
 571   return output;
 572 }
 573 }  // namespace
 574
 575 std::string SyncerProtoUtil::ClientToServerResponseDebugString(
 576     const ClientToServerResponse& response) {
 577   // Add more handlers as needed.
 578   std::string output;
 579   if (response.has_get_updates())
 580     output.append(GetUpdatesResponseString(response.get_updates()));
 581   return output;
 582 }
 583
 584 }  // namespace syncer