fix(cdm): send a PlayReady licence without an XML declaration as XML

A remote CDM tried base64 first on any licence not starting with "<?xml", which can decode XML text into garbage. Also lists L3 as a device_name.

docs/guide/drm-and-cdm.md

@@ -336,7 +336,7 @@ includes an intelligent key-caching layer:
 remote_cdm:
   - name: decryptlabs
     type: decrypt_labs
-    device_name: L1        # ChromeCDM, L1, L2 (Widevine) or SL2, SL3 (PlayReady)
+    device_name: L1        # ChromeCDM, L1, L2, L3 (Widevine) or SL2, SL3 (PlayReady)
     # host: https://keyxtractor.decryptlabs.com   # optional, this is the default
     # secret: ...          # optional if decrypt_labs_api_key is set globally
 

docs/reference/configuration/drm.md

@@ -117,7 +117,7 @@ styles: `Device Type`/`device_type`, `System ID`/`system_id`, `Security Level`/`
 | Field | Default | Notes |
 |-------|---------|-------|
 | `host` | `https://keyxtractor.decryptlabs.com` | |
-| `device_name` | `ChromeCDM` | `ChromeCDM`, `L1`, `L2` (Widevine) or `SL2`, `SL3` (PlayReady) |
+| `device_name` | `ChromeCDM` | `ChromeCDM`, `L1`, `L2`, `L3` (Widevine) or `SL2`, `SL3` (PlayReady). The host decides which of these names it serves. |
 | `secret` | from [`decrypt_labs_api_key`](misc.md#external-api-keys) | Sent as the `decrypt-labs-api-key` header. An error is raised if neither is set. |
 | `system_id` | `26830` (Widevine), `0` (PlayReady) | |
 | `security_level` | Widevine `3`; PlayReady `2000` for `SL2`, else `3000` | |

tests/core/test_remote_cdm_playready_licence.py

@@ -0,0 +1,77 @@
+"""A remote CDM must send a PlayReady licence to the host as the XML it received.
+
+A licence server may return the SOAP envelope with or without an XML declaration.
+``base64.b64decode`` drops every character it cannot read, so XML text can decode
+without an error and the host then receives bytes that are not a licence.
+"""
+
+from __future__ import annotations
+
+import base64
+from typing import Any
+
+import pytest
+
+from unshackle.core.cdm.custom_remote_cdm import CustomRemoteCDM
+from unshackle.core.cdm.decrypt_labs_remote_cdm import DecryptLabsRemoteCDM
+
+pytestmark = pytest.mark.unit
+
+ENVELOPE = (
+    '<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"><soap:Body>'
+    "<AcquireLicenseResponse><License>AAAA</License></AcquireLicenseResponse>"
+    "</soap:Body></soap:Envelope>"
+)
+
+
+class Sent(Exception):
+    """Stops ``parse_license`` after the request body has been captured."""
+
+
+def decrypt_labs_cdm() -> tuple[Any, str]:
+    return DecryptLabsRemoteCDM(secret="x", host="https://cdm.test", device_name="SL3"), "decrypt_labs_session_id"
+
+
+def custom_cdm() -> tuple[Any, str]:
+    cdm = CustomRemoteCDM(host="https://cdm.test", device={"name": "SL3000", "type": "PLAYREADY"})
+    return cdm, "remote_session_id"
+
+
+def licence_sent(cdm: Any, remote_id_key: str, licence: str) -> bytes:
+    """Run ``parse_license`` on a session that has a challenge, and return the licence bytes it posts."""
+    session_id = cdm.open()
+    cdm.set_pssh_b64("UFNTSA==", session_id=session_id)
+    cdm._sessions[session_id].update({"challenge": b"challenge", remote_id_key: "remote", "pssh": object()})
+
+    body: dict[str, Any] = {}
+
+    def capture(_url: str, json: dict[str, Any], **_: Any) -> None:
+        body.update(json)
+        raise Sent
+
+    cdm._http_session.post = capture
+    with pytest.raises(Sent):
+        cdm.parse_license(session_id, licence)
+    return base64.b64decode(body["license_response"])
+
+
+@pytest.mark.parametrize("make_cdm", [decrypt_labs_cdm, custom_cdm])
+@pytest.mark.parametrize(
+    "licence",
+    [
+        ENVELOPE,
+        '<?xml version="1.0" encoding="utf-8"?>' + ENVELOPE,
+        "\n  " + ENVELOPE,
+        # Each length makes a different count of base64 characters, so one of them decodes without an error.
+        *(ENVELOPE.replace("AAAA", "A" * n) for n in range(5, 8)),
+    ],
+)
+def test_a_playready_xml_licence_is_sent_as_it_is(make_cdm: Any, licence: str) -> None:
+    cdm, remote_id_key = make_cdm()
+    assert licence_sent(cdm, remote_id_key, licence) == licence.encode("utf-8")
+
+
+@pytest.mark.parametrize("make_cdm", [decrypt_labs_cdm, custom_cdm])
+def test_a_base64_licence_is_still_decoded(make_cdm: Any) -> None:
+    cdm, remote_id_key = make_cdm()
+    assert licence_sent(cdm, remote_id_key, base64.b64encode(b"binary licence").decode()) == b"binary licence"

unshackle/core/cdm/custom_remote_cdm.py

@@ -940,7 +940,7 @@ class CustomRemoteCDM:
             raise ValueError("No challenge available - call get_license_challenge first")
 
         if isinstance(license_message, str):
-            if self.is_playready and license_message.strip().startswith("<?xml"):
+            if self.is_playready and license_message.lstrip().startswith("<"):
                 license_message = license_message.encode("utf-8")
             else:
                 try:

unshackle/core/cdm/decrypt_labs_remote_cdm.py

@@ -114,7 +114,7 @@ class DecryptLabsRemoteCDM:
         Args:
             secret: Decrypt Labs API key (matches config format)
             host: Decrypt Labs API host URL (matches config format)
-            device_name: DRM system device name. Widevine takes ChromeCDM, L1 or L2, and PlayReady takes SL2 or SL3
+            device_name: DRM system device name. Widevine takes ChromeCDM, L1, L2 or L3, and PlayReady takes SL2 or SL3
             service_name: Service tag for content key caching and vault operations
             vaults: Vaults instance for local content key caching
             device_type: Device type (CHROME, ANDROID, PLAYREADY) - for compatibility
@@ -585,7 +585,7 @@ class DecryptLabsRemoteCDM:
             raise ValueError("No challenge available - call get_license_challenge first")
 
         if isinstance(license_message, str):
-            if self.is_playready and license_message.strip().startswith("<?xml"):
+            if self.is_playready and license_message.lstrip().startswith("<"):
                 license_message = license_message.encode("utf-8")
             else:
                 try: