fix(dash): license ClearKeyCENC before decrypt

tests/core/test_dash_clearkey_licensing.py

@@ -0,0 +1,84 @@
+"""Regression test for DASH ``org.w3.clearkey`` licensing in ``DASH.download_track``.
+
+The download path gated content-key licensing on ``isinstance(drm, (Widevine,
+PlayReady))``, so a ClearKeyCENC track never reached its license callback, left
+``content_keys`` empty, and aborted at ``drm.decrypt`` with "Cannot decrypt a
+Track without any Content Keys". This drives the real ``download_track`` under
+``DOWNLOAD_LICENCE_ONLY`` (returns straight after licensing, no segment fetch or
+decrypt) and asserts the ClearKeyCENC drm is licensed.
+"""
+
+from __future__ import annotations
+
+from functools import partial
+from typing import Any
+from uuid import UUID
+
+from unshackle.core.constants import DOWNLOAD_LICENCE_ONLY
+from unshackle.core.drm.clearkey_cenc import ClearKeyCENC
+from unshackle.core.manifests.dash import DASH
+from unshackle.core.tracks.track import DownloadContext
+
+KID = UUID("9eb4050d-e44b-4802-932e-27d75083e266")
+KEY = bytes.fromhex("ccd0064c43f7e9fcbaa9b12af3fd1f40")
+LAURL = "https://license.example.test/clearkey"
+MANIFEST_URL = "https://example.test/manifest.mpd"
+
+MPD = f"""<?xml version="1.0" encoding="utf-8"?>
+<MPD xmlns="urn:mpeg:dash:schema:mpd:2011" xmlns:cenc="urn:mpeg:cenc:2013"
+     xmlns:dashif="https://dashif.org/CPS" type="static" mediaPresentationDuration="PT10S">
+  <Period id="0">
+    <AdaptationSet contentType="video" mimeType="video/mp4" lang="en">
+      <Representation id="video1" codecs="avc1.640028" width="1920" height="1080" bandwidth="5000000">
+        <ContentProtection schemeIdUri="urn:uuid:e2719d58-a985-b3c9-781a-b030af78d30e"
+                           value="ClearKey1.0" cenc:default_KID="{KID}">
+          <dashif:Laurl>{LAURL}</dashif:Laurl>
+        </ContentProtection>
+        <SegmentList timescale="1000">
+          <SegmentURL media="https://example.test/seg1.m4s" duration="1000"/>
+        </SegmentList>
+      </Representation>
+    </AdaptationSet>
+  </Period>
+</MPD>
+"""
+
+
+class RecordingLicence:
+    """License callback stub: records its call and populates content keys."""
+
+    def __init__(self) -> None:
+        self.calls: list[tuple[Any, Any]] = []
+
+    def __call__(self, drm: Any, track_kid: Any = None) -> None:
+        self.calls.append((drm, track_kid))
+        for kid in drm.kids:
+            drm.content_keys[kid] = KEY.hex()
+
+
+def test_download_track_licenses_clearkey_cenc(tmp_path, monkeypatch) -> None:
+    track = DASH.from_text(MPD, MANIFEST_URL).to_tracks().videos[0]
+    # KID normally comes from the init segment; short-circuit the probe (offline).
+    monkeypatch.setattr(track, "get_key_id", lambda *args, **kwargs: KID)
+
+    licence = RecordingLicence()
+    ctx = DownloadContext(
+        save_path=tmp_path / "video.mp4",
+        save_dir=tmp_path / "video_segments",
+        progress=partial(lambda **_: None),
+        license_widevine=licence,
+        cdm=None,
+    )
+
+    DOWNLOAD_LICENCE_ONLY.set()
+    try:
+        DASH.download_track(track=track, ctx=ctx)
+    finally:
+        DOWNLOAD_LICENCE_ONLY.clear()
+
+    assert len(licence.calls) == 1, "ClearKeyCENC track was never licensed"
+    drm, track_kid = licence.calls[0]
+    assert isinstance(drm, ClearKeyCENC)
+    assert track_kid == KID
+    # with content keys populated, decrypt has what it needs
+    assert drm.content_keys == {KID: KEY.hex()}

unshackle/core/manifests/dash.py

@@ -425,8 +425,8 @@ class DASH:
         if track.drm:
             track_kid = track_kid or track.get_key_id(url=segments[0][0], session=session)
             drm = track.get_drm_for_cdm(cdm)
-            if isinstance(drm, (Widevine, PlayReady)):
-                # license and grab content keys
+            if isinstance(drm, (Widevine, PlayReady, ClearKeyCENC)):
+                # license and grab content keys (ClearKeyCENC uses no CDM)
                 try:
                     if not license_widevine:
                         raise ValueError("license_widevine func must be supplied to use DRM")