PropertiesChanged callback not being triggered

[Hudo Assenço]

Hi all,

I am trying to debug a problem I am having with an IoT framework (Iotivity). The client side of the framework cannot receive data from the server through bluetooth. After digging the code, I found the problem is the callback responsible for receiving the data is not being called. 

The callback is connected to the PropertiesChanged signal after the GattServices discovery happens, here: https://github.com/iotivity/iotivity/blob/1.1-rel/resource/csdk/connectivity/src/bt_le_adapter/linux/client.c#L279 <https://github.com/iotivity/iotivity/blob/1.1-rel/resource/csdk/connectivity/src/bt_le_adapter/linux/client.c#L279>

And it is defined here: https://github.com/iotivity/iotivity/blob/1.1-rel/resource/csdk/connectivity/src/bt_le_adapter/linux/client.c#L84 <https://github.com/iotivity/iotivity/blob/1.1-rel/resource/csdk/connectivity/src/bt_le_adapter/linux/client.c#L84>

I put some logs to be sure that the right characteristic is being connected, and it is:
46:43.819 INFO: BLE_CLIENT: IN CAGattClientSetupCharacteristics
46:43.839 INFO: BLE_CLIENT: connecting  CAGattClientOnCharacteristicPropertiesChanged, UUID: e9241982-4580-42c4-8831-95048216b256
PATH: /org/bluez/hci0/dev_C7_6A_A9_0B_DD_5F/service000c/char000f
46:43.969 INFO: BLE_CLIENT: is g-properties-changed connected: 1

I also monitored the bus with dbus-monitor and I got the signals that I was looking for:
signal sender=:1.4 -> dest=(null destination) serial=953 path=/org/bluez/hci0/dev_C7_6A_A9_0B_DD_5F/service000c/char000f; interface=org.freedesktop.DBus.Properties; member=PropertiesChanged
  string "org.bluez.GattCharacteristic1"
  array [
     dict entry(
        string "Value"
        variant             array of bytes [
              d8 c6 45 a2 98 02 40 3a 7d 8b e7 b3 6f 69 63 03 72 65 73 11
           ]
     )
  ]
  array [
  ]
signal sender=:1.4 -> dest=(null destination) serial=954 path=/org/bluez/hci0/dev_C7_6A_A9_0B_DD_5F/service000c/char000f; interface=org.freedesktop.DBus.Properties; member=PropertiesChanged
  string "org.bluez.GattCharacteristic1"
  array [
     dict entry(
        string "Value"
        variant             array of bytes [
              3c e1 fe db c0 ff 81 bf 62 64 69 60 65 6c 69 6e 6b 73 83 a4
           ]
     )
  ]
  array [
  ]
But the “CAGattClientOnCharacteristicPropertiesChanged” callback is never called.

I posted this same issue in their mailing list but had no help. So I though someone here with more experience with bluetooth could help me in debug this problem further. I was looking for a way to check which signal handlers are connected to the dbus object through command line but I couldn’t find.

More info:
BlueZ 5.37
Kernel 3.10

Thanks,
Hudo.
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