HAP: wait for MTU to process reconnection event

When HAP reconnect, it sends indication of all events that happen during
the disconnection.
But it should wait for the profile to be ready and for the MTU to have
been negotiated or else the remote may not be ready yet.

As a side effect of this, the current GattServer doesn't re-populate the
handle of subscriber during a reconnection, we have to bypass this check
to send the notification

bumble/profiles/hap.py

@@ -273,12 +273,19 @@ class HearingAccessService(gatt.TemplateService):
             def on_disconnection(_reason) -> None:
                 self.currently_connected_clients.discard(connection)
 
+            @connection.on(connection.EVENT_CONNECTION_ATT_MTU_UPDATE)
+            def on_mtu_update(*_: Any) -> None:
+                self.on_incoming_connection(connection)
+
+            @connection.on(connection.EVENT_CONNECTION_ENCRYPTION_CHANGE)
+            def on_encryption_change(*_: Any) -> None:
+                self.on_incoming_connection(connection)
+
             @connection.on(connection.EVENT_PAIRING)
             def on_pairing(*_: Any) -> None:
-                self.on_incoming_paired_connection(connection)
+                self.on_incoming_connection(connection)
 
-            if connection.peer_resolvable_address:
-                self.on_incoming_paired_connection(connection)
+            self.on_incoming_connection(connection)
 
         self.hearing_aid_features_characteristic = gatt.Characteristic(
             uuid=gatt.GATT_HEARING_AID_FEATURES_CHARACTERISTIC,
@@ -315,9 +322,30 @@ class HearingAccessService(gatt.TemplateService):
             ]
         )
 
-    def on_incoming_paired_connection(self, connection: Connection):
+    def on_incoming_connection(self, connection: Connection):
         '''Setup initial operations to handle a remote bonded HAP device'''
         # TODO Should we filter on HAP device only ?
+
+        if not connection.is_encrypted:
+            logging.debug(f'HAS: {connection.peer_address} is not encrypted')
+            return
+
+        if not connection.peer_resolvable_address:
+            logging.debug(f'HAS: {connection.peer_address} is not paired')
+            return
+
+        if connection.att_mtu < 49:
+            logging.debug(
+                f'HAS: {connection.peer_address} invalid MTU={connection.att_mtu}'
+            )
+            return
+
+        if connection.peer_address in self.currently_connected_clients:
+            logging.debug(
+                f'HAS: Already connected to {connection.peer_address} nothing to do'
+            )
+            return
+
         self.currently_connected_clients.add(connection)
         if (
             connection.peer_address
@@ -457,6 +485,7 @@ class HearingAccessService(gatt.TemplateService):
                     connection,
                     self.hearing_aid_preset_control_point,
                     value=op_list[0].to_bytes(len(op_list) == 1),
+                    force=True,  # TODO GATT notification subscription should be persistent
                 )
                 # Remove item once sent, and keep the non sent item in the list
                 op_list.pop(0)

tests/hap_test.py

@@ -82,7 +82,6 @@ async def hap_client():
     )
 
     await devices.setup_connection()
-    # TODO negotiate MTU > 49 to not truncate preset names
 
     # Mock encryption.
     devices.connections[0].encryption = 1  # type: ignore
@@ -93,6 +92,9 @@ async def hap_client():
     )
 
     peer = device.Peer(devices.connections[1])  # type: ignore
+    await peer.request_mtu(49)
+    peer2 = device.Peer(devices.connections[0])  # type: ignore
+    await peer2.request_mtu(49)
     hap_client = await peer.discover_service_and_create_proxy(
         hap.HearingAccessServiceProxy
     )