esp_prov : Runtime discovery of Service UUID and endpoint name mapping

List of changes:
* Retrieve UUID property from Bluez device object before connecting to retrieve UUID contained in advertisement
* Read Characteristic User Descriptions attribute of each UUID for mapping endpoint names
* To support older implementations with hardcoded Name-UUID map, revert to fallback mode in order if advertisement data has no UUID field

tools/esp_prov/esp_prov.py

@@ -60,6 +60,13 @@ def get_transport(sel_transport, softap_endpoint=None, ble_devname=None):
         if (sel_transport == 'softap'):
             tp = transport.Transport_Softap(softap_endpoint)
         elif (sel_transport == 'ble'):
+            # BLE client is now capable of automatically figuring out
+            # the primary service from the advertisement data and the
+            # characteristics corresponding to each endpoint.
+            # Below, the service_uuid field and 16bit UUIDs in the nu_lookup
+            # table are provided only to support devices running older firmware,
+            # in which case, the automated discovery will fail and the client
+            # will fallback to using the provided UUIDs instead
             tp = transport.Transport_BLE(devname=ble_devname,
                                          service_uuid='0000ffff-0000-1000-8000-00805f9b34fb',
                                          nu_lookup={'prov-session': 'ff51',

tools/esp_prov/transport/ble_cli.py

@@ -15,6 +15,7 @@
 
 from __future__ import print_function
 from builtins import input
+from future.utils import iteritems
 
 import platform
 
@@ -40,20 +41,24 @@ if platform.system() == 'Linux':
 
 # BLE client (Linux Only) using Bluez and DBus
 class BLE_Bluez_Client:
-    def connect(self, devname, iface, srv_uuid):
+    def connect(self, devname, iface, chrc_names, fallback_srv_uuid):
         self.devname = devname
-        self.srv_uuid = srv_uuid
+        self.srv_uuid_fallback = fallback_srv_uuid
+        self.chrc_names = [name.lower() for name in chrc_names]
         self.device = None
         self.adapter = None
         self.adapter_props = None
         self.services = None
+        self.nu_lookup = None
+        self.characteristics = dict()
+        self.srv_uuid_adv = None
 
         dbus.mainloop.glib.DBusGMainLoop(set_as_default=True)
         bus = dbus.SystemBus()
         manager = dbus.Interface(bus.get_object("org.bluez", "/"), "org.freedesktop.DBus.ObjectManager")
         objects = manager.GetManagedObjects()
 
-        for path, interfaces in objects.items():
+        for path, interfaces in iteritems(objects):
             adapter = interfaces.get("org.bluez.Adapter1")
             if adapter is not None:
                 if path.endswith(iface):
@@ -94,8 +99,8 @@ class BLE_Bluez_Client:
         manager = dbus.Interface(bus.get_object("org.bluez", "/"), "org.freedesktop.DBus.ObjectManager")
         objects = manager.GetManagedObjects()
         dev_path = None
-        for path, interfaces in objects.items():
-            if "org.bluez.Device1" not in interfaces.keys():
+        for path, interfaces in iteritems(objects):
+            if "org.bluez.Device1" not in interfaces:
                 continue
             if interfaces["org.bluez.Device1"].get("Name") == self.devname:
                 dev_path = path
@@ -106,6 +111,19 @@ class BLE_Bluez_Client:
 
         try:
             self.device = bus.get_object("org.bluez", dev_path)
+            try:
+                uuids = self.device.Get('org.bluez.Device1', 'UUIDs',
+                                        dbus_interface='org.freedesktop.DBus.Properties')
+                # There should be 1 service UUID in advertising data
+                # If bluez had cached an old version of the advertisement data
+                # the list of uuids may be incorrect, in which case connection
+                # or service discovery may fail the first time. If that happens
+                # the cache will be refreshed before next retry
+                if len(uuids) == 1:
+                    self.srv_uuid_adv = uuids[0]
+            except dbus.exceptions.DBusException as e:
+                print(e)
+
             self.device.Connect(dbus_interface='org.bluez.Device1')
         except Exception as e:
             print(e)
@@ -116,35 +134,84 @@ class BLE_Bluez_Client:
         bus = dbus.SystemBus()
         manager = dbus.Interface(bus.get_object("org.bluez", "/"), "org.freedesktop.DBus.ObjectManager")
         objects = manager.GetManagedObjects()
-        srv_path = None
-        for path, interfaces in objects.items():
-            if "org.bluez.GattService1" not in interfaces.keys():
+        service_found = False
+        for srv_path, srv_interfaces in iteritems(objects):
+            if "org.bluez.GattService1" not in srv_interfaces:
+                continue
+            if not srv_path.startswith(self.device.object_path):
                 continue
-            if path.startswith(self.device.object_path):
-                service = bus.get_object("org.bluez", path)
-                uuid = service.Get('org.bluez.GattService1', 'UUID',
+            service = bus.get_object("org.bluez", srv_path)
+            srv_uuid = service.Get('org.bluez.GattService1', 'UUID',
                                    dbus_interface='org.freedesktop.DBus.Properties')
-                if uuid == self.srv_uuid:
-                    srv_path = path
+
+            # If service UUID doesn't match the one found in advertisement data
+            # then also check if it matches the fallback UUID
+            if srv_uuid not in [self.srv_uuid_adv, self.srv_uuid_fallback]:
+                continue
+
+            nu_lookup = dict()
+            characteristics = dict()
+            for chrc_path, chrc_interfaces in iteritems(objects):
+                if "org.bluez.GattCharacteristic1" not in chrc_interfaces:
+                    continue
+                if not chrc_path.startswith(service.object_path):
+                    continue
+                chrc = bus.get_object("org.bluez", chrc_path)
+                uuid = chrc.Get('org.bluez.GattCharacteristic1', 'UUID',
+                                dbus_interface='org.freedesktop.DBus.Properties')
+                characteristics[uuid] = chrc
+                for desc_path, desc_interfaces in iteritems(objects):
+                    if "org.bluez.GattDescriptor1" not in desc_interfaces:
+                        continue
+                    if not desc_path.startswith(chrc.object_path):
+                        continue
+                    desc = bus.get_object("org.bluez", desc_path)
+                    desc_uuid = desc.Get('org.bluez.GattDescriptor1', 'UUID',
+                                         dbus_interface='org.freedesktop.DBus.Properties')
+                    if desc_uuid[4:8] != '2901':
+                        continue
+                    try:
+                        readval = desc.ReadValue({}, dbus_interface='org.bluez.GattDescriptor1')
+                    except dbus.exceptions.DBusException:
+                        break
+                    found_name = ''.join(chr(b) for b in readval).lower()
+                    nu_lookup[found_name] = uuid
                     break
 
-        if srv_path is None:
+            match_found = True
+            for name in self.chrc_names:
+                if name not in nu_lookup:
+                    # Endpoint name not present
+                    match_found = False
+                    break
+
+            # Create lookup table only if all endpoint names found
+            self.nu_lookup = [None, nu_lookup][match_found]
+            self.characteristics = characteristics
+            service_found = True
+
+            # If the service UUID matches that in the advertisement
+            # we can stop the search now. If it doesn't match, we
+            # have found the service corresponding to the fallback
+            # UUID, in which case don't break and keep searching
+            # for the advertised service
+            if srv_uuid == self.srv_uuid_adv:
+                break
+
+        if not service_found:
             self.device.Disconnect(dbus_interface='org.bluez.Device1')
+            if self.adapter:
+                self.adapter.RemoveDevice(self.device)
             self.device = None
+            self.nu_lookup = None
+            self.characteristics = dict()
             raise RuntimeError("Provisioning service not found")
 
-        self.characteristics = dict()
-        for path, interfaces in objects.items():
-            if "org.bluez.GattCharacteristic1" not in interfaces.keys():
-                continue
-            if path.startswith(srv_path):
-                chrc = bus.get_object("org.bluez", path)
-                uuid = chrc.Get('org.bluez.GattCharacteristic1', 'UUID',
-                                dbus_interface='org.freedesktop.DBus.Properties')
-                self.characteristics[uuid] = chrc
+    def get_nu_lookup(self):
+        return self.nu_lookup
 
     def has_characteristic(self, uuid):
-        if uuid in self.characteristics.keys():
+        if uuid in self.characteristics:
             return True
         return False
 
@@ -154,6 +221,8 @@ class BLE_Bluez_Client:
             if self.adapter:
                 self.adapter.RemoveDevice(self.device)
             self.device = None
+            self.nu_lookup = None
+            self.characteristics = dict()
         if self.adapter_props:
             self.adapter_props.Set("org.bluez.Adapter1", "Powered", dbus.Boolean(0))
 
@@ -180,7 +249,7 @@ class BLE_Bluez_Client:
 
 # Console based BLE client for Cross Platform support
 class BLE_Console_Client:
-    def connect(self, devname, iface, srv_uuid):
+    def connect(self, devname, iface, chrc_names, fallback_srv_uuid):
         print("BLE client is running in console mode")
         print("\tThis could be due to your platform not being supported or dependencies not being met")
         print("\tPlease ensure all pre-requisites are met to run the full fledged client")
@@ -189,11 +258,14 @@ class BLE_Console_Client:
         if resp != 'Y' and resp != 'y':
             return False
         print("BLECLI >> List available attributes of the connected device")
-        resp = input("BLECLI >> Is the service UUID '" + srv_uuid + "' listed among available attributes? [y/n] ")
+        resp = input("BLECLI >> Is the service UUID '" + fallback_srv_uuid + "' listed among available attributes? [y/n] ")
         if resp != 'Y' and resp != 'y':
             return False
         return True
 
+    def get_nu_lookup(self):
+        return None
+
     def has_characteristic(self, uuid):
         resp = input("BLECLI >> Is the characteristic UUID '" + uuid + "' listed among available attributes? [y/n] ")
         if resp != 'Y' and resp != 'y':

tools/esp_prov/transport/transport_ble.py

@@ -27,19 +27,28 @@ class Transport_BLE(Transport):
             # Calculate characteristic UUID for each endpoint
             nu_lookup[name] = service_uuid[:4] + '{:02x}'.format(
                 int(nu_lookup[name], 16) & int(service_uuid[4:8], 16)) + service_uuid[8:]
-        self.name_uuid_lookup = nu_lookup
 
         # Get BLE client module
         self.cli = ble_cli.get_client()
 
         # Use client to connect to BLE device and bind to service
-        if not self.cli.connect(devname=devname, iface='hci0', srv_uuid=service_uuid):
+        if not self.cli.connect(devname=devname, iface='hci0',
+                                chrc_names=nu_lookup.keys(),
+                                fallback_srv_uuid=service_uuid):
             raise RuntimeError("Failed to initialize transport")
 
-        # Check if expected characteristics are provided by the service
-        for name in self.name_uuid_lookup.keys():
-            if not self.cli.has_characteristic(self.name_uuid_lookup[name]):
-                raise RuntimeError("'" + name + "' endpoint not found")
+        # Irrespective of provided parameters, let the client
+        # generate a lookup table by reading advertisement data
+        # and characteristic user descriptors
+        self.name_uuid_lookup = self.cli.get_nu_lookup()
+
+        # If that doesn't work, use the lookup table provided as parameter
+        if self.name_uuid_lookup is None:
+            self.name_uuid_lookup = nu_lookup
+            # Check if expected characteristics are provided by the service
+            for name in self.name_uuid_lookup.keys():
+                if not self.cli.has_characteristic(self.name_uuid_lookup[name]):
+                    raise RuntimeError("'" + name + "' endpoint not found")
 
     def __del__(self):
         # Make sure device is disconnected before application gets closed