[vrv] fix CMS signing query extraction(closes #21809)

youtube_dl/extractor/vrv.py

@@ -64,7 +64,15 @@ class VRVBaseIE(InfoExtractor):
 
     def _call_cms(self, path, video_id, note):
         if not self._CMS_SIGNING:
-            self._CMS_SIGNING = self._call_api('index', video_id, 'CMS Signing')['cms_signing']
+            index = self._call_api('index', video_id, 'CMS Signing')
+            self._CMS_SIGNING = index.get('cms_signing') or {}
+            if not self._CMS_SIGNING:
+                for signing_policy in index.get('signing_policies', []):
+                    signing_path = signing_policy.get('path')
+                    if signing_path and signing_path.startswith('/cms/'):
+                        name, value = signing_policy.get('name'), signing_policy.get('value')
+                        if name and value:
+                            self._CMS_SIGNING[name] = value
         return self._download_json(
             self._API_DOMAIN + path, video_id, query=self._CMS_SIGNING,
             note='Downloading %s JSON metadata' % note, headers=self.geo_verification_headers())