feat(core): add SilentError and suppres message response on Cancel from Host in pairing phase when waiting for user interaction

[no changelog]

core/src/apps/thp/pairing.py

@@ -5,6 +5,7 @@ from trezor import loop, protobuf
 from trezor.crypto.hashlib import sha256
 from trezor.enums import MessageType, ThpPairingMethod
 from trezor.messages import (
+    Cancel,
     ThpCodeEntryChallenge,
     ThpCodeEntryCommitment,
     ThpCodeEntryCpaceHost,
@@ -23,7 +24,7 @@ from trezor.messages import (
     ThpQrCodeTag,
     ThpStartPairingRequest,
 )
-from trezor.wire.errors import ActionCancelled, UnexpectedMessage
+from trezor.wire.errors import ActionCancelled, SilentError, UnexpectedMessage
 from trezor.wire.thp import ChannelState, ThpError, crypto
 from trezor.wire.thp.pairing_context import PairingContext
 
@@ -97,7 +98,9 @@ async def handle_pairing_request(
     await _prepare_pairing(ctx)
     await ctx.write(ThpPairingPreparationsFinished())
     ctx.channel_ctx.set_channel_state(ChannelState.TP3)
-    response = await show_display_data(ctx, _get_possible_pairing_methods(ctx))
+    response = await show_display_data(
+        ctx, _get_possible_pairing_methods_and_cancel(ctx)
+    )
     if __debug__:
         from trezor.messages import DebugLinkGetState
 
@@ -107,8 +110,12 @@ async def handle_pairing_request(
             dl_state = await dispatch_DebugLinkGetState(response)
             assert dl_state is not None
             await ctx.write(dl_state)
-            response = await show_display_data(ctx, _get_possible_pairing_methods(ctx))
-
+            response = await show_display_data(
+                ctx, _get_possible_pairing_methods_and_cancel(ctx)
+            )
+    if Cancel.is_type_of(response):
+        ctx.channel_ctx.clear()
+        raise SilentError("Action was cancelled by the Host")
     # TODO disable NFC (if enabled)
     response = await _handle_different_pairing_methods(ctx, response)
 
@@ -369,6 +376,12 @@ def _is_method_included(ctx: PairingContext, method: ThpPairingMethod) -> bool:
 # Helpers - getters
 
 
+def _get_possible_pairing_methods_and_cancel(ctx: PairingContext) -> Tuple[int, ...]:
+    r = _get_possible_pairing_methods(ctx)
+    mtype = Cancel.MESSAGE_WIRE_TYPE
+    return r + ((mtype,) if mtype is not None else ())
+
+
 def _get_possible_pairing_methods(ctx: PairingContext) -> Tuple[int, ...]:
     r = tuple(
         _get_message_type_for_method(method)

core/src/trezor/wire/errors.py

@@ -8,6 +8,12 @@ class Error(Exception):
         self.message = message
 
 
+class SilentError(Exception):
+    def __init__(self, message: str) -> None:
+        super().__init__()
+        self.message = message
+
+
 class UnexpectedMessage(Error):
     def __init__(self, message: str) -> None:
         super().__init__(FailureType.UnexpectedMessage, message)

core/src/trezor/wire/thp/pairing_context.py

@@ -7,7 +7,7 @@ from trezor.crypto import random
 from trezor.ui.layouts.tt import RustLayout
 from trezor.wire import context, message_handler, protocol_common
 from trezor.wire.context import UnexpectedMessageException
-from trezor.wire.errors import ActionCancelled
+from trezor.wire.errors import ActionCancelled, SilentError
 from trezor.wire.protocol_common import Context, Message
 
 if TYPE_CHECKING:
@@ -233,7 +233,9 @@ async def handle_pairing_request_message(
         # We might handle only the few common cases here, like
         # Initialize and Cancel.
         return exc.msg
-
+    except SilentError as exc:
+        if __debug__:
+            log.error(__name__, "SilentError: %s", exc.message)
     except BaseException as exc:
         # Either:
         # - the message had a type that has a registered handler, but does not have