Add exception on small buffer and fix Connecion WRITE handling

ports/nrf/common-hal/_bleio/Connection.c

@@ -162,7 +162,8 @@ bool connection_on_ble_evt(ble_evt_t *ble_evt, void *self_in) {
                 self->do_bond_cccds = true;
                 self->do_bond_cccds_request_time = supervisor_ticks_ms64();
             }
-            break;
+            // Return false so other handlers get this event as well.
+            return false;
 
         case BLE_GATTS_EVT_SYS_ATTR_MISSING:
             sd_ble_gatts_sys_attr_set(self->conn_handle, NULL, 0, 0);

ports/nrf/common-hal/_bleio/PacketBuffer.c

@@ -148,6 +148,7 @@ STATIC bool packet_buffer_on_ble_server_evt(ble_evt_t *ble_evt, void *param) {
             // A client wrote to this server characteristic.
 
             ble_gatts_evt_write_t *evt_write = &ble_evt->evt.gatts_evt.params.write;
+
             // Event handle must match the handle for my characteristic.
             if (evt_write->handle == self->characteristic->handle) {
                 if (self->conn_handle == BLE_CONN_HANDLE_INVALID) {
@@ -261,8 +262,7 @@ int common_hal_bleio_packet_buffer_readinto(bleio_packet_buffer_obj_t *self, uin
     sd_nvic_critical_region_enter(&is_nested_critical_region);
 
     if (packet_length > len) {
-        // TODO: raise an exception.
-        packet_length = len;
+        return len - packet_length;
     }
 
     ringbuf_get_n(&self->ringbuf, data, packet_length);

shared-bindings/_bleio/PacketBuffer.c

@@ -109,7 +109,12 @@ STATIC mp_obj_t bleio_packet_buffer_readinto(mp_obj_t self_in, mp_obj_t buffer_o
     mp_buffer_info_t bufinfo;
     mp_get_buffer_raise(buffer_obj, &bufinfo, MP_BUFFER_WRITE);
 
-    return MP_OBJ_NEW_SMALL_INT(common_hal_bleio_packet_buffer_readinto(self, bufinfo.buf, bufinfo.len));
+    int size = common_hal_bleio_packet_buffer_readinto(self, bufinfo.buf, bufinfo.len);
+    if (size < 0) {
+        mp_raise_ValueError_varg(translate("Buffer too short by %d bytes"), size * -1);
+    }
+
+    return MP_OBJ_NEW_SMALL_INT(size);
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_2(bleio_packet_buffer_readinto_obj, bleio_packet_buffer_readinto);