BLE: try to pick the correct descriptor to write to

The ordering on Mac appears to be random, but after looking through the
various successful logs of BLE downloads, it seems we always wrote to the
ClientCharacteristicConfiguration descriptor. So try to find that one first,
and only grab the first descriptor in the list if we didn't find a
ClientCharacteristicConfiguration descriptor.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

1 files changed, 13 insertions, 2 deletions

diff --git a/core/qt-ble.cpp b/core/qt-ble.cpp
index eca615fbe..92a78ae65 100644
--- a/core/qt-ble.cpp
+++ b/core/qt-ble.cpp
@@ -382,8 +382,19 @@ dc_status_t qt_ble_open(dc_custom_io_t *io, dc_context_t *context, const char *d
 				qDebug() << "Descriptor:" << d.name() << "uuid:" << d.uuid().toString();
 
 			if (!l.isEmpty()) {
-				d = l.first();
-				qDebug() << "now writing \"0x0100\" to the first descriptor";
+				bool foundCCC = false;
+				foreach (d, l) {
+					if (d.type() == QBluetoothUuid::ClientCharacteristicConfiguration) {
+						// pick the correct characteristic
+						foundCCC = true;
+						break;
+					}
+				}
+				if (!foundCCC)
+					// if we didn't find a ClientCharacteristicConfiguration, try the first one
+					d = l.first();
+
+				qDebug() << "now writing \"0x0100\" to the descriptor" << d.uuid().toString();
 
 				ble->preferredService()->writeDescriptor(d, QByteArray::fromHex("0100"));
 			}