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.

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"