feat(cardav): support result truncation for addressbook federation

apps/dav/lib/CardDAV/AddressBook.php

@@ -8,7 +8,6 @@
 namespace OCA\DAV\CardDAV;
 
 use OCA\DAV\DAV\Sharing\IShareable;
-use OCA\DAV\Exception\UnsupportedLimitOnInitialSyncException;
 use OCP\DB\Exception;
 use OCP\IL10N;
 use OCP\Server;
@@ -234,9 +233,6 @@ private function canWrite(): bool {
 	}
 
 	public function getChanges($syncToken, $syncLevel, $limit = null) {
-		if (!$syncToken && $limit) {
-			throw new UnsupportedLimitOnInitialSyncException();
-		}
 
 		return parent::getChanges($syncToken, $syncLevel, $limit);
 	}

apps/dav/lib/CardDAV/CardDavBackend.php

@@ -23,9 +23,11 @@
 use OCP\DB\Exception;
 use OCP\DB\QueryBuilder\IQueryBuilder;
 use OCP\EventDispatcher\IEventDispatcher;
+use OCP\IConfig;
 use OCP\IDBConnection;
 use OCP\IUserManager;
 use PDO;
+use Psr\Log\LoggerInterface;
 use Sabre\CardDAV\Backend\BackendInterface;
 use Sabre\CardDAV\Backend\SyncSupport;
 use Sabre\CardDAV\Plugin;
@@ -59,6 +61,8 @@ public function __construct(
 		private IUserManager $userManager,
 		private IEventDispatcher $dispatcher,
 		private Sharing\Backend $sharingBackend,
+		private LoggerInterface $logger,
+		private IConfig $config,
 	) {
 	}
 
@@ -851,6 +855,10 @@ public function deleteCard($addressBookId, $cardUri) {
 	 * @return array
 	 */
 	public function getChangesForAddressBook($addressBookId, $syncToken, $syncLevel, $limit = null) {
+		if ($limit === null) {
+			$limit = $this->config->getSystemValueInt('carddav_sync_request_limit', 1);
+
+		}
 		// Current synctoken
 		return $this->atomic(function () use ($addressBookId, $syncToken, $syncLevel, $limit) {
 			$qb = $this->db->getQueryBuilder();
@@ -873,8 +881,34 @@ public function getChangesForAddressBook($addressBookId, $syncToken, $syncLevel,
 				'modified' => [],
 				'deleted' => [],
 			];
-
-			if ($syncToken) {
+			$this->logger->error('getChangesForAddressBook', ['syncToken' => $syncToken, 'currentToken' => $currentToken, 'limit' => $limit]);
+			if (str_starts_with($syncToken, 'init_')) {
+				$syncValues = explode('_', $syncToken);
+				$lastID = $syncValues[1];
+				$initialSyncToken = $syncValues[2];
+				$qb = $this->db->getQueryBuilder();
+				$qb->select('id', 'uri')
+					->from('cards')
+					->where(
+						$qb->expr()->andX(
+							$qb->expr()->eq('addressbookid', $qb->createNamedParameter($addressBookId)),
+							$qb->expr()->gt('id', $qb->createNamedParameter($lastID)))
+					)->orderBy('id')
+					->setMaxResults($limit);
+				$stmt = $qb->executeQuery();
+				$values = $stmt->fetchAll(\PDO::FETCH_ASSOC);
+				$stmt->closeCursor();
+				if (count($values) === 0) {
+					$result['syncToken'] = $initialSyncToken;
+					$result['result_truncated'] = false;
+					$result['added'] = [];
+				} else {
+					$lastID = end($values)['id'];
+					$result['added'] = array_column($values, 'uri');
+					$result['syncToken'] = count($result['added']) === $limit ? "init_{$lastID}_$initialSyncToken" : $initialSyncToken ;
+					$result['result_truncated'] = count($result['added']) === $limit;
+				}
+			} elseif ($syncToken) {
 				$qb = $this->db->getQueryBuilder();
 				$qb->select('uri', 'operation')
 					->from('addressbookchanges')
@@ -899,6 +933,8 @@ public function getChangesForAddressBook($addressBookId, $syncToken, $syncLevel,
 				// last change on a node is relevant.
 				while ($row = $stmt->fetch(\PDO::FETCH_ASSOC)) {
 					$changes[$row['uri']] = $row['operation'];
+					// get the last synctoken, needed in case a limit was set
+					$result['syncToken'] = $row['synctoken'];
 				}
 				$stmt->closeCursor();
 
@@ -917,14 +953,28 @@ public function getChangesForAddressBook($addressBookId, $syncToken, $syncLevel,
 				}
 			} else {
 				$qb = $this->db->getQueryBuilder();
-				$qb->select('uri')
+				$qb->select('id', 'uri')
 					->from('cards')
 					->where(
 						$qb->expr()->eq('addressbookid', $qb->createNamedParameter($addressBookId))
 					);
 				// No synctoken supplied, this is the initial sync.
-				$stmt = $qb->executeQuery();
-				$result['added'] = $stmt->fetchAll(\PDO::FETCH_COLUMN);
+				if (is_int($limit) && $limit > 0) {
+					$qb->setMaxResults($limit);
+					$stmt = $qb->executeQuery();
+					$values = $stmt->fetchAll(\PDO::FETCH_ASSOC);
+					$lastID = end($values)['id'];
+					if (count(array_values($values)) === $limit) {
+						$result['syncToken'] = 'init_' . $lastID . '_' . $currentToken;
+						$result['result_truncated'] = true;
+					}
+				} else {
+					$stmt = $qb->executeQuery();
+					$values = $stmt->fetchAll(\PDO::FETCH_ASSOC);
+					$this->logger->error('getChangesForAddressBook', ['values' => $values]);
+				}
+				$result['added'] = array_column($values, 'uri');
+
 				$stmt->closeCursor();
 			}
 			return $result;

apps/dav/lib/CardDAV/SyncService.php

@@ -63,6 +63,7 @@ public function syncRemoteAddressBook(string $url, string $userName, string $add
 			$this->logger->error('Client exception:', ['app' => 'dav', 'exception' => $ex]);
 			throw $ex;
 		}
+		$this->logger->error('sync response', [$response]);
 
 		// 3. apply changes
 		// TODO: use multi-get for download

apps/dav/lib/CardDAV/SystemAddressbook.php

@@ -8,7 +8,6 @@
  */
 namespace OCA\DAV\CardDAV;
 
-use OCA\DAV\Exception\UnsupportedLimitOnInitialSyncException;
 use OCA\Federation\TrustedServers;
 use OCP\Accounts\IAccountManager;
 use OCP\IConfig;
@@ -212,14 +211,7 @@ public function getChild($name): Card {
 		}
 		return new Card($this->carddavBackend, $this->addressBookInfo, $obj);
 	}
-
-	/**
-	 * @throws UnsupportedLimitOnInitialSyncException
-	 */
 	public function getChanges($syncToken, $syncLevel, $limit = null) {
-		if (!$syncToken && $limit) {
-			throw new UnsupportedLimitOnInitialSyncException();
-		}
 
 		if (!$this->carddavBackend instanceof SyncSupport) {
 			return null;

apps/dav/lib/RootCollection.php

@@ -124,6 +124,8 @@ public function __construct() {
 		);
 
 		$contactsSharingBackend = \OC::$server->get(\OCA\DAV\CardDAV\Sharing\Backend::class);
+		$logger = \OC::$server->get(\Psr\Log\LoggerInterface::class);
+		$config = \OC::$server->get(IConfig::class);
 
 		$pluginManager = new PluginManager(\OC::$server, \OC::$server->query(IAppManager::class));
 		$usersCardDavBackend = new CardDavBackend(
@@ -132,6 +134,8 @@ public function __construct() {
 			$userManager,
 			$dispatcher,
 			$contactsSharingBackend,
+			$logger,
+			$config
 		);
 		$usersAddressBookRoot = new AddressBookRoot($userPrincipalBackend, $usersCardDavBackend, $pluginManager, $userSession->getUser(), $groupManager, 'principals/users');
 		$usersAddressBookRoot->disableListing = $disableListing;
@@ -142,6 +146,8 @@ public function __construct() {
 			$userManager,
 			$dispatcher,
 			$contactsSharingBackend,
+			$logger,
+			$config
 		);
 		$systemAddressBookRoot = new AddressBookRoot(new SystemPrincipalBackend(), $systemCardDavBackend, $pluginManager, $userSession->getUser(), $groupManager, 'principals/system');
 		$systemAddressBookRoot->disableListing = $disableListing;

apps/dav/lib/Server.php

@@ -160,7 +160,8 @@
 
 		$this->server->addPlugin(new ExceptionLoggerPlugin('webdav', $logger));
 		$this->server->addPlugin(new LockPlugin());
-		$this->server->addPlugin(new \Sabre\DAV\Sync\Plugin());
+		$logger = \OC::$server->get(LoggerInterface::class);
+		$this->server->addPlugin(new \Sabre\DAV\Sync\Plugin($logger));
 
 		// acl
 		$acl = new DavAclPlugin();

apps/federation/lib/SyncFederationAddressBooks.php

@@ -52,6 +52,10 @@
 			try {
 				$newToken = $this->syncService->syncRemoteAddressBook($url, $cardDavUser, $addressBookUrl, $sharedSecret, $syncToken, $targetBookId, $targetPrincipal, $targetBookProperties);
 				if ($newToken !== $syncToken) {
+					// Finish truncated initial sync.
+					if (strpos($newToken, 'init') !== false) {
+						$newToken = $this->syncTruncatedAddressBook($url, $cardDavUser, $addressBookUrl, $sharedSecret, $newToken, $targetBookId, $targetPrincipal, $targetBookProperties);
+					}
 					$this->dbHandler->setServerStatus($url, TrustedServers::STATUS_OK, $newToken);
 				} else {
 					$this->logger->debug("Sync Token for $url unchanged from previous sync");
@@ -76,4 +80,12 @@
 			}
 		}
 	}
+
+	private function syncTruncatedAddressBook(string $url, string $cardDavUser, string $addressBookUrl, string $sharedSecret, string $syncToken, int $targetBookId, string $targetPrincipal, array $targetBookProperties): string {
+		$newToken = $this->syncService->syncRemoteAddressBook($url, $cardDavUser, $addressBookUrl, $sharedSecret, $syncToken, $targetBookId, $targetPrincipal, $targetBookProperties);
+		while (strpos($newToken, 'init') !== false) {
+			$newToken = $this->syncService->syncRemoteAddressBook($url, $cardDavUser, $addressBookUrl, $sharedSecret, $syncToken, $targetBookId, $targetPrincipal, $targetBookProperties);
+		}
+		return $newToken;
+	}
 }

config/config.sample.php

@@ -347,6 +347,11 @@
  */
 'carddav_sync_request_timeout' => 30,
 
+/**
+ * The limit applied to the initial synchronization report request, e.g. federated system address books (as run by `occ federation:sync-addressbooks`).
+ */
+'carddav_initial_sync_request_limit' => 1000,
+
 /**
  * `true` enabled a relaxed session timeout, where the session timeout would no longer be
  * handled by Nextcloud but by either the PHP garbage collection or the expiration of

lib/public/Http/Client/IClient.php

@@ -22,6 +22,14 @@ interface IClient {
 	 */
 	public const DEFAULT_REQUEST_TIMEOUT = 30;
 
+	/**
+	 * Default limit for address book intial sync
+	 *
+	 * @since 31.0.0
+	 */
+
+	public const DEFAULT_ADDRESSBOOK_INITIAL_SYNC_LIMIT = 1;
+
 	/**
 	 * Sends a GET request
 	 * @param string $uri