py-tcti: add draft tcti for usage with py-tcti

Author: Johannes Holland

src/tpmstream/__init__.py

@@ -1 +1,5 @@
 __version__ = "0.1.10"
+
+# make tcti_init visible for py-tcti
+# see https://github.com/tpm2-software/tpm2-tss/pull/2749
+from tpmstream.tcti import tcti_init  # isort:skip

src/tpmstream/tcti/__init__.py

@@ -0,0 +1,70 @@
+import_error = None
+try:
+    from tpm2_pytss import TCTILdr
+except ImportError as error:
+    import_error = error
+
+from tpmstream.io.binary import Binary
+from tpmstream.io.pretty import Pretty
+from tpmstream.spec.commands import Command, Response
+
+
+# To use tpmstream with tcti-py, we define a tcti
+# see https://github.com/tpm2-software/tpm2-tss/pull/2749
+class TpmstreamTCTI(object):
+    def __init__(self, args: str | None):
+        def parse_args(args: str | None):
+            if args is None:
+                return {"name": None, "conf": None}
+            if ":" not in args:
+                return {"name": args, "conf": None}
+
+            name, conf = args.split(":", maxsplit=1)
+            return {"name": name, "conf": conf}
+
+        nameconf = parse_args(args)
+        print(f"PYTHON: Initializing TCTI Ldr with mod: {nameconf}")
+        self._tcti = TCTILdr(**nameconf)
+        self._command_code = None
+
+    @property
+    def magic(self):
+        return 0x74706D7374726561
+
+    def receive(self, timeout: int) -> bytes:
+        result = self._tcti.receive(timeout=timeout)
+
+        events = Binary.marshal(
+            tpm_type=Response,
+            buffer=result,
+            command_code=self._command_code,
+            abort_on_error=False,
+        )
+        for line in Pretty.unmarshal(events):
+            if isinstance(line, bytes):
+                print(" " + binascii.hexlify(line).decode(), end="")
+            else:
+                print(line)
+
+        return result
+
+    def transmit(self, buffer: bytes):
+        events = Binary.marshal(
+            tpm_type=Command,
+            buffer=buffer,
+            abort_on_error=False,
+        )
+        for line in Pretty.unmarshal(events):
+            if isinstance(line, bytes):
+                print(" " + binascii.hexlify(line).decode(), end="")
+            else:
+                print(line)
+        self._command_code = int.from_bytes(buffer[6:10], byteorder="big")
+
+        self._tcti.transmit(buffer)
+
+
+def tcti_init(args: str) -> TpmstreamTCTI:
+    if import_error:
+        raise import_error
+    return TpmstreamTCTI(args)