Merge pull request #49470 from nextcloud/backport/49311/stable28

Author: provokateurin

lib/private/OCM/OCMDiscoveryService.php

@@ -72,7 +72,12 @@ public function discover(string $remote, bool $skipCache = false): IOCMProvider
 
 		if (!$skipCache) {
 			try {
-				$this->provider->import(json_decode($this->cache->get($remote) ?? '', true, 8, JSON_THROW_ON_ERROR) ?? []);
+				$cached = $this->cache->get($remote);
+				if ($cached === false) {
+					throw new OCMProviderException('Previous discovery failed.');
+				}
+
+				$this->provider->import(json_decode($cached ?? '', true, 8, JSON_THROW_ON_ERROR) ?? []);
 				if ($this->supportedAPIVersion($this->provider->getApiVersion())) {
 					return $this->provider; // if cache looks valid, we use it
 				}
@@ -99,8 +104,10 @@ public function discover(string $remote, bool $skipCache = false): IOCMProvider
 				$this->cache->set($remote, $body, 60 * 60 * 24);
 			}
 		} catch (JsonException|OCMProviderException $e) {
+			$this->cache->set($remote, false, 5 * 60);
 			throw new OCMProviderException('data returned by remote seems invalid - ' . ($body ?? ''));
 		} catch (\Exception $e) {
+			$this->cache->set($remote, false, 5 * 60);
 			$this->logger->warning('error while discovering ocm provider', [
 				'exception' => $e,
 				'remote' => $remote
@@ -109,6 +116,7 @@ public function discover(string $remote, bool $skipCache = false): IOCMProvider
 		}
 
 		if (!$this->supportedAPIVersion($this->provider->getApiVersion())) {
+			$this->cache->set($remote, false, 5 * 60);
 			throw new OCMProviderException('API version not supported');
 		}