fix(caldav): encode calendar URIs with umlauts for activities

Signed-off-by: Richard Steinmetz <richard@steinmetz.cloud>

2 files changed, 62 insertions, 8 deletions

diff --git a/apps/dav/lib/CalDAV/Activity/Provider/Event.php b/apps/dav/lib/CalDAV/Activity/Provider/Event.php
index 45d4f731e20..959c0a815dd 100644
--- a/apps/dav/lib/CalDAV/Activity/Provider/Event.php
+++ b/apps/dav/lib/CalDAV/Activity/Provider/Event.php
@@ -76,14 +76,15 @@ class Event extends Base {
 				// The calendar app needs to be manually loaded for the routes to be loaded
 				OC_App::loadApp('calendar');
 				$linkData = $eventData['link'];
+				$calendarUri = $this->urlencodeLowerHex($linkData['calendar_uri']);
 				if ($affectedUser === $linkData['owner']) {
-					$objectId = base64_encode($this->url->getWebroot() . '/remote.php/dav/calendars/' . $linkData['owner'] . '/' . $linkData['calendar_uri'] . '/' . $linkData['object_uri']);
+					$objectId = base64_encode($this->url->getWebroot() . '/remote.php/dav/calendars/' . $linkData['owner'] . '/' . $calendarUri . '/' . $linkData['object_uri']);
 				} else {
 					// Can't use the "real" owner and calendar names here because we create a custom
 					// calendar for incoming shares with the name "<calendar>_shared_by_<sharer>".
 					// Hack: Fix the link by generating it for the incoming shared calendar instead,
 					//       as seen from the affected user.
-					$objectId = base64_encode($this->url->getWebroot() . '/remote.php/dav/calendars/' . $affectedUser . '/' . $linkData['calendar_uri'] . '_shared_by_' . $linkData['owner'] . '/' . $linkData['object_uri']);
+					$objectId = base64_encode($this->url->getWebroot() . '/remote.php/dav/calendars/' . $affectedUser . '/' . $calendarUri . '_shared_by_' . $linkData['owner'] . '/' . $linkData['object_uri']);
 				}
 				$link = [
 					'view' => 'dayGridMonth',
@@ -241,4 +242,16 @@ class Event extends Base {
 		}
 		return $parameter;
 	}
+
+	/**
+	 * Return urlencoded string but with lower cased hex sequences.
+	 * The remaining casing will be untouched.
+	 */
+	private function urlencodeLowerHex(string $raw): string {
+		return preg_replace_callback(
+			'/%[0-9A-F]{2}/',
+			static fn (array $matches) => strtolower($matches[0]),
+			urlencode($raw),
+		);
+	}
 }
diff --git a/apps/dav/tests/unit/CalDAV/Activity/Provider/EventTest.php b/apps/dav/tests/unit/CalDAV/Activity/Provider/EventTest.php
index b0b2cc936a5..ec237825731 100644
--- a/apps/dav/tests/unit/CalDAV/Activity/Provider/EventTest.php
+++ b/apps/dav/tests/unit/CalDAV/Activity/Provider/EventTest.php
@@ -129,17 +129,58 @@ class EventTest extends TestCase {
 		$this->assertEquals($result, $this->invokePrivate($this->provider, 'generateObjectParameter', [$objectParameter, $affectedUser]));
 	}
 
-	public function testGenerateObjectParameterWithSharedCalendar(): void {
-		$link = [
-			'object_uri' => 'someuuid.ics',
-			'calendar_uri' => 'personal',
-			'owner' => 'sharer'
+	public static function generateObjectParameterLinkEncodingDataProvider(): array {
+		return [
+			[ // Shared calendar
+				[
+					'object_uri' => 'someuuid.ics',
+					'calendar_uri' => 'personal',
+					'owner' => 'sharer'
+				],
+				base64_encode('/remote.php/dav/calendars/sharee/personal_shared_by_sharer/someuuid.ics'),
+			],
+			[ // Shared calendar with umlauts
+				[
+					'object_uri' => 'someuuid.ics',
+					'calendar_uri' => 'umlaut_äüöß',
+					'owner' => 'sharer'
+				],
+				base64_encode('/remote.php/dav/calendars/sharee/umlaut_%c3%a4%c3%bc%c3%b6%c3%9f_shared_by_sharer/someuuid.ics'),
+			],
+			[ // Shared calendar with umlauts and mixed casing
+				[
+					'object_uri' => 'someuuid.ics',
+					'calendar_uri' => 'Umlaut_äüöß',
+					'owner' => 'sharer'
+				],
+				base64_encode('/remote.php/dav/calendars/sharee/Umlaut_%c3%a4%c3%bc%c3%b6%c3%9f_shared_by_sharer/someuuid.ics'),
+			],
+			[ // Owned calendar with umlauts
+				[
+					'object_uri' => 'someuuid.ics',
+					'calendar_uri' => 'umlaut_äüöß',
+					'owner' => 'sharee'
+				],
+				base64_encode('/remote.php/dav/calendars/sharee/umlaut_%c3%a4%c3%bc%c3%b6%c3%9f/someuuid.ics'),
+			],
+			[ // Owned calendar with umlauts and mixed casing
+				[
+					'object_uri' => 'someuuid.ics',
+					'calendar_uri' => 'Umlaut_äüöß',
+					'owner' => 'sharee'
+				],
+				base64_encode('/remote.php/dav/calendars/sharee/Umlaut_%c3%a4%c3%bc%c3%b6%c3%9f/someuuid.ics'),
+			],
 		];
+	}
+
+	/** @dataProvider generateObjectParameterLinkEncodingDataProvider */
+	public function testGenerateObjectParameterLinkEncoding(array $link, string $objectId): void {
 		$generatedLink = [
 			'view' => 'dayGridMonth',
 			'timeRange' => 'now',
 			'mode' => 'sidebar',
-			'objectId' => base64_encode('/remote.php/dav/calendars/sharee/' . $link['calendar_uri'] . '_shared_by_sharer/' . $link['object_uri']),
+			'objectId' => $objectId,
 			'recurrenceId' => 'next'
 		];
 		$this->appManager->expects($this->once())