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unshackle/tests/remote/unit/test_server_cdm_key_verification.py
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Python

"""A server vault key is unproven until the client decodes with it.
Over --remote with server_cdm the server never sees a segment, so the client holds a
vault-sourced key back from its own vaults, checks the decode, and reports a bad pair to
the server. The client never learns which server vault answered: the server keeps the
name on its served-key record and flags the row itself, only for a pair it served.
"""
import json
from types import SimpleNamespace
from uuid import UUID
import pytest
from unshackle.core.api import handlers
from unshackle.core.api.errors import APIError
from unshackle.core.api.session_store import SessionEntry
from unshackle.core.drm import BlowfishStripe
from unshackle.core.remote_service import RemoteService, ServerVault
pytestmark = pytest.mark.unit
KID = UUID("161219ec3df64e0eadbb3827c0ccc46d")
CDM_KID = UUID("43de497c6d1945f49acc2951696ec628")
def remote_service() -> RemoteService:
svc = RemoteService.__new__(RemoteService)
svc._track_alias = {}
svc._title_alias = {}
svc.server_vault_keys = {}
svc.server_vault = ServerVault(svc)
svc._session_id = "sess"
svc.client_licensed = set()
svc.log = SimpleNamespace(warning=lambda *a, **k: None)
return svc
def test_client_marks_vault_keys_and_forgets_cdm_keys():
svc = remote_service()
svc.note_vault_keys({KID.hex: "v", CDM_KID.hex: "c"}, {KID.hex})
assert svc.server_vault_keys == {KID: "v"}
# a re-licence that came from the CDM clears the marker
svc.note_vault_keys({KID.hex: "v2"}, set())
assert svc.server_vault_keys == {}
def test_server_vault_flag_posts_only_the_pair():
svc = remote_service()
posted: list = []
svc.client = SimpleNamespace(post_optional=lambda ep, data: posted.append((ep, data)) or {})
assert svc.server_vault.report_now
svc.server_vault.flag_bad_key("SVC", KID, "v", "server_cdm")
assert posted == [("/api/session/sess/keys/bad", {"kid": KID.hex, "key": "v"})]
class _Vault:
local = True
def __init__(self):
self.flagged: list = []
def flag_bad_key(self, service, kid, key, source):
self.flagged.append((service, kid, key, source))
@pytest.fixture
def session(monkeypatch):
entry = SessionEntry(session_id="sess", service_tag="SVC", service_instance=SimpleNamespace())
handlers.note_served_keys(entry, {KID.hex: "v", CDM_KID.hex: "c"}, {KID.hex: "sqlite"})
assert entry.served_keys == {KID.hex: ("v", "sqlite"), CDM_KID.hex: ("c", "cdm")}
async def validated(session_id, request):
return entry
monkeypatch.setattr(handlers, "get_validated_session", validated)
monkeypatch.setattr(handlers, "require_authenticated", lambda s: None)
vault = _Vault()
monkeypatch.setattr(handlers, "load_server_vaults", lambda name: SimpleNamespace(vaults=[vault], service="SVC"))
return entry, vault
async def test_server_flags_a_served_pair_with_its_own_vault_name(session, monkeypatch):
entry, vault = session
monkeypatch.setattr(handlers, "CACHED_PAIRS", {("SimpleNamespace", KID.hex, "v")})
resp = await handlers.session_bad_key_handler({"kid": KID.hex, "key": "v"}, "sess")
assert resp.status == 200
assert vault.flagged == [("SVC", KID, "v", "sqlite")]
assert KID.hex not in entry.served_keys
assert not handlers.CACHED_PAIRS
with pytest.raises(APIError):
await handlers.session_bad_key_handler({"kid": CDM_KID.hex, "key": "nope"}, "sess")
assert len(vault.flagged) == 1
async def test_server_does_not_flag_a_pair_its_cdm_licensed(session):
entry, vault = session
resp = await handlers.session_bad_key_handler({"kid": CDM_KID.hex, "key": "c"}, "sess")
assert json.loads(resp.body) == {"flagged": False}
assert vault.flagged == []
class _WV:
def __init__(self, b64, kids):
self._pssh = SimpleNamespace(dumps=lambda: b64)
self.kids = kids
_WV.__name__ = "Widevine"
async def test_batch_reports_vault_keys_from_the_init_segment_pssh(monkeypatch):
"""A vault hit on the init-segment PSSH retry must reach `vault_keys` like a manifest one."""
track = SimpleNamespace(id="vid", drm=[_WV("manifest", [KID])], get_key_id=lambda init: CDM_KID)
session = SessionEntry(session_id="sess", service_tag="SVC", service_instance=SimpleNamespace())
session.tracks = {"vid": track}
async def validated(sid, req):
return session
def fake_single(service, title, track, pssh_str, drm_type, request, sources=None, refusal=None, vault_only=False):
if pssh_str == "init":
sources[CDM_KID.hex] = "sqlite"
return {CDM_KID.hex: "v"}
return {KID.hex: "c"}
monkeypatch.setattr(handlers, "get_validated_session", validated)
monkeypatch.setattr(handlers, "server_cdm_allowed", lambda request, tag: True)
monkeypatch.setattr(handlers, "ensure_track_drm", lambda track, session=None, init_data=None: None)
monkeypatch.setattr(handlers, "find_title_for_track", lambda tid, session: SimpleNamespace())
monkeypatch.setattr(handlers, "detect_cdm_type_for_service", lambda tag, cfg: "widevine")
monkeypatch.setattr(handlers, "resolve_device_name", lambda *a, **k: "dev")
monkeypatch.setattr(handlers, "fetch_init_segment", lambda track, sess: b"init")
monkeypatch.setattr(
handlers, "drm_from_init_segment", lambda track, session=None, init_data=None: [_WV("init", [CDM_KID])]
)
monkeypatch.setattr(handlers, "handle_single_server_cdm", fake_single)
monkeypatch.setattr(handlers.config, "serve", {"users": {}}, raising=False)
resp = await handlers.session_license_handler(
{"mode": "server_cdm", "track_ids": ["vid"], "drm_type": "widevine"}, "sess", None
)
payload = json.loads(resp.body)
assert payload["keys"] == {"vid": {CDM_KID.hex: "v"}}
assert payload["vault_keys"] == [CDM_KID.hex]
assert session.served_keys == {CDM_KID.hex: ("v", "sqlite")}
async def test_server_tells_a_remote_vault_only_when_it_served_the_pair(monkeypatch, session):
entry, local = session
bystander, source = _Vault(), _Vault()
bystander.local = source.local = False
bystander.name, source.name = "other", "sqlite"
monkeypatch.setattr(
handlers, "load_server_vaults", lambda name: SimpleNamespace(vaults=[local, bystander, source], service="SVC")
)
await handlers.session_bad_key_handler({"kid": KID.hex, "key": "v"}, "sess")
assert local.flagged == [("SVC", KID, "v", "sqlite")]
assert source.flagged == [("SVC", KID, "v", "sqlite")]
assert bystander.flagged == []
def test_resolve_server_keys_does_not_warn_for_clear_tracks(monkeypatch):
"""A requested track the server lists in clear_tracks carries no DRM, so its
missing keys are expected and draw no warning."""
svc = remote_service()
warnings: list = []
svc.log = SimpleNamespace(warning=lambda msg, *a, **k: warnings.append(msg), debug=lambda *a, **k: None)
svc._server_cdm = True
svc.drain_server_logs = lambda: None
svc.client = SimpleNamespace(post=lambda ep, data: {"keys": {}, "clear_tracks": ["a-1"]})
video_track = SimpleNamespace(id="v-1", drm=None)
audio_track = SimpleNamespace(id="a-1", drm=None)
class Tracks(list):
videos = [video_track]
audio = [audio_track]
svc.resolve_server_keys(SimpleNamespace(tracks=Tracks([video_track, audio_track])))
assert warnings == ["Server CDM returned no content keys for track v-1"]
def resolve(manifest_drm, drm_type="widevine"):
"""Run resolve_server_keys for one track the server answers with its own key and a sibling."""
svc = remote_service()
svc.log = SimpleNamespace(warning=lambda *a, **k: None, debug=lambda *a, **k: None)
svc._server_cdm = True
svc.drain_server_logs = lambda: None
keys = {CDM_KID.hex: "bb" * 16, KID.hex: "aa" * 16}
svc.client = SimpleNamespace(post=lambda ep, data: {"keys": {"v-1": keys}, "drm_type": drm_type})
track = SimpleNamespace(id="v-1", drm=manifest_drm)
class Tracks(list):
videos = [track]
audio: list = []
svc.resolve_server_keys(SimpleNamespace(tracks=Tracks([track])))
assert set(track.drm[0].content_keys) == {KID, CDM_KID}
return track.drm[0]
def test_resolve_server_keys_names_only_the_manifest_kids():
"""Sibling keys in the licence stay content keys but are not KIDs the track names."""
from pywidevine.pssh import PSSH
from unshackle.core.drm import Widevine
widevine = Widevine(pssh=PSSH.new(system_id=PSSH.SystemId.Widevine, key_ids=[KID]))
assert resolve([widevine]).kids == [KID]
playready = RemoteService.create_drm_stub("playready", [KID.hex])
assert resolve([playready], "playready").kids == [KID]
def test_resolve_server_keys_names_every_kid_without_manifest_drm():
assert set(resolve(None).kids) == {KID, CDM_KID}
def test_reconstruct_drm_keeps_the_default_kid_of_a_pssh_without_kids():
from pywidevine.pssh import PSSH
from unshackle.core.drm import real_kids
from unshackle.core.remote_service import reconstruct_drm
content_id_only = PSSH.new(system_id=PSSH.SystemId.Widevine, init_data=b"\x22\x03abc")
(drm,) = reconstruct_drm([{"type": "widevine", "pssh": content_id_only.dumps(), "kids": [str(KID)]}])
assert real_kids(drm) == [KID]
def test_a_cdm_licence_unflags_a_pair_a_client_reported(monkeypatch, tmp_path):
"""The CDM returned the reported pair, so the client's decode check was wrong."""
from unshackle.core.vaults import Vaults
from unshackle.vaults.SQLite import SQLite
local = SQLite("local", tmp_path / "local.db")
vaults = Vaults("SVC")
vaults.vaults = [local]
vaults.flag_bad_key(KID, "ab" * 16)
monkeypatch.setattr(handlers, "load_server_vaults", lambda service: vaults)
monkeypatch.setattr(handlers, "CACHED_PAIRS", set())
handlers.cache_to_vaults({KID.hex: "ab" * 16}, "SVC")
assert not local.is_bad_key(KID, "ab" * 16)
assert local.get_key(KID, "SVC") == "ab" * 16
async def test_a_stripe_cipher_track_is_clear_and_never_licensed(monkeypatch):
"""A track whose only DRM needs no licence goes to clear_tracks and keeps its DRM for the client."""
track = SimpleNamespace(id="aud", drm=[BlowfishStripe(bytes(16))])
session = SessionEntry(session_id="sess", service_tag="SVC", service_instance=SimpleNamespace())
session.tracks = {"aud": track}
async def validated(sid, req):
return session
monkeypatch.setattr(handlers, "get_validated_session", validated)
monkeypatch.setattr(handlers, "server_cdm_allowed", lambda request, tag: True)
monkeypatch.setattr(handlers, "ensure_track_drm", lambda track, session=None, init_data=None: None)
monkeypatch.setattr(handlers, "find_title_for_track", lambda tid, session: SimpleNamespace())
monkeypatch.setattr(handlers, "detect_cdm_type_for_service", lambda tag, cfg: "widevine")
monkeypatch.setattr(handlers, "resolve_device_name", lambda *a, **k: "dev")
monkeypatch.setattr(handlers, "fetch_init_segment", lambda track, sess: None)
monkeypatch.setattr(handlers, "handle_single_server_cdm", lambda *a, **k: pytest.fail("licensed a clear track"))
monkeypatch.setattr(handlers.config, "serve", {"users": {}}, raising=False)
resp = await handlers.session_license_handler(
{"mode": "server_cdm", "track_ids": ["aud"], "drm_type": "widevine"}, "sess", None
)
assert json.loads(resp.body)["clear_tracks"] == ["aud"]
assert isinstance(track.drm[0], BlowfishStripe)