feat(python): support future Trezor models

fixes #3993

python/.changelog.d/3993.added

@@ -0,0 +1 @@
+Added support for Trezor models not known by the current version of the library.

python/src/trezorlib/client.py

@@ -278,19 +278,10 @@ class TrezorClient(Generic[UI]):
         """Update internal fields based on passed-in Features message."""
 
         if not self.model:
-            # Trezor Model One bootloader 1.8.0 or older does not send model name
-            model = models.by_internal_name(features.internal_model)
-            if model is None:
-                model = models.by_name(features.model or "1")
-            if model is None:
-                raise RuntimeError(
-                    "Unsupported Trezor model"
-                    f" (internal_model: {features.internal_model}, model: {features.model})"
-                )
-            self.model = model
+            self.model = models.detect(features)
 
         if features.vendor not in self.model.vendors:
-            raise RuntimeError("Unsupported device")
+            raise exceptions.TrezorException(f"Unrecognized vendor: {features.vendor}")
 
         self.features = features
         self.version = (

python/src/trezorlib/models.py

@@ -19,7 +19,7 @@ from __future__ import annotations
 from dataclasses import dataclass
 from typing import Collection, Tuple
 
-from . import mapping
+from . import mapping, messages
 
 UsbId = Tuple[int, int]
 
@@ -35,6 +35,8 @@ class TrezorModel:
     usb_ids: Collection[UsbId]
     default_mapping: mapping.ProtobufMapping
 
+    is_unknown: bool = False
+
 
 # ==== internal names ====
 
@@ -129,6 +131,11 @@ TREZORS = frozenset({T1B1, T2T1, T2B1, T3T1, T3B1, T3W1, DISC1, DISC2})
 
 
 def by_name(name: str | None) -> TrezorModel | None:
+    """Try to find a TrezorModel by its name.
+
+    This is a fallback function in case `internal_model` is not available. For general
+    model detection, prefer `detect()`.
+    """
     if name is None:
         return T1B1
     for model in TREZORS:
@@ -138,9 +145,45 @@ def by_name(name: str | None) -> TrezorModel | None:
 
 
 def by_internal_name(name: str | None) -> TrezorModel | None:
+    """Try to find a TrezorModel by its internal name.
+
+    Used internally as part of `detect()` routine. For general model detection, prefer
+    calling `detect()`.
+    """
     if name is None:
         return None
     for model in TREZORS:
         if model.internal_name == name:
             return model
     return None
+
+
+def detect(features: messages.Features) -> TrezorModel:
+    """Detect Trezor model from its Features response.
+
+    If `internal_name` is sent, tries to detect model based on it. If not (in older
+    firmwares), falls back to `model` field.
+
+    If no match is found, returns an ad-hoc TrezorModel instance whose fields are set
+    based on the provided model and/or internal model. This can either represent a newer
+    model that is not recognized by the current version of the library, or a fork that
+    responds to Trezor wire protocol but is not actually a Trezor.
+    """
+    model = by_internal_name(features.internal_model)
+    if model is not None:
+        return model
+    model = by_name(features.model)
+    if model is not None:
+        return model
+
+    return TrezorModel(
+        name=features.model or "Unknown",
+        internal_name=features.internal_model or "????",
+        minimum_version=(0, 0, 0),
+        # Allowed vendors are the internal VENDORS list instead of trusting features.vendor.
+        # That way, an unrecognized non-Trezor device will fail the check in TrezorClient.
+        vendors=VENDORS,
+        usb_ids=(),
+        default_mapping=mapping.DEFAULT_MAPPING,
+        is_unknown=True,
+    )

python/tools/pybridge.py

@@ -104,9 +104,7 @@ class Transport:
         self.transport = transport
 
         client = TrezorClient(transport, ui=SilentUI())
-        self.model = (
-            trezorlib.models.by_name(client.features.model) or trezorlib.models.TREZOR_T
-        )
+        self.model = client.model
         client.end_session()
 
     def acquire(self, sid: str) -> str: