add passkey delegate

bumble/pairing.py

@@ -222,6 +222,14 @@ class PairingDelegate:
             ),
         )
 
+    async def generate_passkey(self) -> int:
+        """
+        Return a passkey value between 0 and 999999 (inclusive).
+        """
+
+        # By default, generate a random passkey.
+        return secrets.randbelow(1000000)
+
 
 # -----------------------------------------------------------------------------
 class PairingConfig:

bumble/smp.py

@@ -934,10 +934,9 @@ class Session:
 
         utils.cancel_on_event(self.connection, 'disconnection', prompt())
 
-    def display_passkey(self) -> None:
-        # Generate random Passkey/PIN code
-        self.passkey = secrets.randbelow(1000000)
-        assert self.passkey is not None
+    async def display_passkey(self) -> None:
+        # Get the passkey value from the delegate
+        self.passkey = await self.pairing_config.delegate.generate_passkey()
         logger.debug(f'Pairing PIN CODE: {self.passkey:06}')
         self.passkey_ready.set()
 
@@ -946,14 +945,7 @@ class Session:
             self.tk = self.passkey.to_bytes(16, byteorder='little')
             logger.debug(f'TK from passkey = {self.tk.hex()}')
 
-        try:
-            utils.cancel_on_event(
-                self.connection,
-                'disconnection',
-                self.pairing_config.delegate.display_number(self.passkey, digits=6),
-            )
-        except Exception as error:
-            logger.warning(f'exception while displaying number: {error}')
+        await self.pairing_config.delegate.display_number(self.passkey, digits=6)
 
     def input_passkey(self, next_steps: Optional[Callable[[], None]] = None) -> None:
         # Prompt the user for the passkey displayed on the peer
@@ -975,9 +967,20 @@ class Session:
         self, next_steps: Optional[Callable[[], None]] = None
     ) -> None:
         if self.passkey_display:
-            self.display_passkey()
-            if next_steps is not None:
-                next_steps()
+
+            async def display_passkey():
+                await self.display_passkey()
+                if next_steps is not None:
+                    next_steps()
+
+            try:
+                utils.cancel_on_event(
+                    self.connection,
+                    'disconnection',
+                    display_passkey(),
+                )
+            except Exception as error:
+                logger.warning(f'exception while displaying passkey: {error}')
         else:
             self.input_passkey(next_steps)
 
@@ -1503,7 +1506,7 @@ class Session:
         # Display a passkey if we need to
         if not self.sc:
             if self.pairing_method == PairingMethod.PASSKEY and self.passkey_display:
-                self.display_passkey()
+                await self.display_passkey()
 
         # Respond
         self.send_pairing_response_command()
@@ -1685,7 +1688,7 @@ class Session:
                 ):
                     return
             elif self.pairing_method == PairingMethod.PASSKEY:
-                assert self.passkey and self.confirm_value
+                assert self.passkey is not None and self.confirm_value is not None
                 # Check that the random value matches what was committed to earlier
                 confirm_verifier = crypto.f4(
                     self.pkb,
@@ -1714,7 +1717,7 @@ class Session:
             ):
                 self.send_pairing_random_command()
             elif self.pairing_method == PairingMethod.PASSKEY:
-                assert self.passkey and self.confirm_value
+                assert self.passkey is not None and self.confirm_value is not None
                 # Check that the random value matches what was committed to earlier
                 confirm_verifier = crypto.f4(
                     self.pka,
@@ -1751,7 +1754,7 @@ class Session:
             ra = bytes(16)
             rb = ra
         elif self.pairing_method == PairingMethod.PASSKEY:
-            assert self.passkey
+            assert self.passkey is not None
             ra = self.passkey.to_bytes(16, byteorder='little')
             rb = ra
         elif self.pairing_method == PairingMethod.OOB:
@@ -1850,19 +1853,23 @@ class Session:
             elif self.pairing_method == PairingMethod.PASSKEY:
                 self.send_pairing_confirm_command()
         else:
+
+            def next_steps():
+                # Send our public key back to the initiator
+                self.send_public_key_command()
+
+                if self.pairing_method in (
+                    PairingMethod.JUST_WORKS,
+                    PairingMethod.NUMERIC_COMPARISON,
+                    PairingMethod.OOB,
+                ):
+                    # We can now send the confirmation value
+                    self.send_pairing_confirm_command()
+
             if self.pairing_method == PairingMethod.PASSKEY:
-                self.display_or_input_passkey()
-
-            # Send our public key back to the initiator
-            self.send_public_key_command()
-
-            if self.pairing_method in (
-                PairingMethod.JUST_WORKS,
-                PairingMethod.NUMERIC_COMPARISON,
-                PairingMethod.OOB,
-            ):
-                # We can now send the confirmation value
-                self.send_pairing_confirm_command()
+                self.display_or_input_passkey(next_steps)
+            else:
+                next_steps()
 
     def on_smp_pairing_dhkey_check_command(
         self, command: SMP_Pairing_DHKey_Check_Command