feat(cdm): Enhance DecryptLabsRemoteCDM to support cached keys and improve license handling

unshackle/core/cdm/decrypt_labs_remote_cdm.py

@@ -26,7 +26,9 @@ class DecryptLabsRemoteCDM(RemoteCdm):
         self.api_session_ids = {}
         self.license_request = None
         self.service_name = service_name
+        self.device_name = device_name
         self.keys = {}
+        self.scheme = "L1" if device_name == "L1" else "widevine"
         try:
             super().__init__(device_type, system_id, security_level, host, secret, device_name)
         except Exception:
@@ -66,16 +68,49 @@ class DecryptLabsRemoteCDM(RemoteCdm):
     ) -> bytes:
         self.pssh = pssh
 
+        request_data = {
+            "init_data": self.pssh.dumps(),
+            "service_certificate": self.req_session.signed_device_certificate,
+            "scheme": self.scheme,
+            "service": self.service_name,
+        }
+        # Add required parameter for L1 scheme
+        if self.scheme == "L1":
+            request_data["get_cached_keys_if_exists"] = True
         res = self.session(
             self.host + "/get-request",
-            {
+            request_data,
-                "init_data": self.pssh.dumps(),
-                "service_certificate": self.req_session.signed_device_certificate,
-                "scheme": "widevine",
-                "service": self.service_name,
-            },
         )
 
+        # Check if we got cached keys instead of a challenge
+        if res.get("message_type") == "cached-keys":
+            # Store cached keys directly
+            if session_id not in self.keys:
+                self.keys[session_id] = []
+            session_keys = self.keys[session_id]
+
+            for cached_key in res.get("cached_keys", []):
+                # Handle KID format - could be hex string or UUID string
+                kid_str = cached_key["kid"]
+                try:
+                    # Try as UUID string first
+                    kid_uuid = UUID(kid_str)
+                except ValueError:
+                    try:
+                        # Try as hex string (like the existing code)
+                        kid_uuid = UUID(bytes=bytes.fromhex(kid_str))
+                    except ValueError:
+                        # Fallback: use Key.kid_to_uuid
+                        kid_uuid = Key.kid_to_uuid(kid_str)
+
+                session_keys.append(Key(kid=kid_uuid, type_="CONTENT", key=bytes.fromhex(cached_key["key"])))
+
+            # Return empty challenge since we already have the keys
+            self.license_request = ""
+            self.api_session_ids[session_id] = None
+            return b""
+
+        # Normal challenge response
         self.license_request = res["challenge"]
         self.api_session_ids[session_id] = res["session_id"]
 
@@ -87,6 +122,10 @@ class DecryptLabsRemoteCDM(RemoteCdm):
             self.keys[session_id] = []
         session_keys = self.keys[session_id]
 
+        # If we already have cached keys and no session_id_api, skip processing
+        if session_id_api is None and session_keys:
+            return
+
         if isinstance(license_message, dict) and "keys" in license_message:
             session_keys.extend(
                 [
@@ -96,14 +135,21 @@ class DecryptLabsRemoteCDM(RemoteCdm):
             )
 
         else:
+            # Ensure license_message is base64 encoded
+            if isinstance(license_message, bytes):
+                license_response_b64 = base64.b64encode(license_message).decode()
+            elif isinstance(license_message, str):
+                license_response_b64 = license_message
+            else:
+                license_response_b64 = str(license_message)
             res = self.session(
                 self.host + "/decrypt-response",
                 {
                     "session_id": session_id_api,
                     "init_data": self.pssh.dumps(),
                     "license_request": self.license_request,
-                    "license_response": license_message,
+                    "license_response": license_response_b64,
-                    "scheme": "widevine",
+                    "scheme": self.scheme,
                 },
             )