func genCharAttr(c *ble.Characteristic, h uint16) (uint16, []*attr) {
vh := h + 1
a := &attr{
h: h,
typ: ble.CharacteristicUUID,
v: append([]byte{byte(c.Property), byte(vh), byte((vh) >> 8)}, c.UUID...),
}
va := &attr{
h: vh,
typ: c.UUID,
v: c.Value,
rh: c.ReadHandler,
wh: c.WriteHandler,
}
c.Handle = h
c.ValueHandle = vh
if c.NotifyHandler != nil || c.IndicateHandler != nil {
c.CCCD = newCCCD(c)
c.Descriptors = append(c.Descriptors, c.CCCD)
}
h += 2
attrs := []*attr{a, va}
for _, d := range c.Descriptors {
attrs = append(attrs, genDescAttr(d, h))
h++
}
a.endh = h - 1
return h, attrs
}
// DiscoverDescriptors finds all the descriptors within a characteristic. [Vol 3, Part G, 4.7.1]
// If filter is specified, only filtered descriptors are returned.
func (p *Client) DiscoverDescriptors(filter []ble.UUID, c *ble.Characteristic) ([]*ble.Descriptor, error) {
p.Lock()
defer p.Unlock()
start := c.ValueHandle + 1
for start <= c.EndHandle {
fmt, b, err := p.ac.FindInformation(start, c.EndHandle)
if err == ble.ErrAttrNotFound {
break
} else if err != nil {
return nil, err
}
length := 2 + 2
if fmt == 0x02 {
length = 2 + 16
}
for len(b) != 0 {
h := binary.LittleEndian.Uint16(b[:2])
u := ble.UUID(b[2:length])
d := &ble.Descriptor{UUID: u, Handle: h}
if filter == nil || ble.Contains(filter, u) {
c.Descriptors = append(c.Descriptors, d)
}
if u.Equal(ble.ClientCharacteristicConfigUUID) {
c.CCCD = d
}
start = h + 1
b = b[length:]
}
}
return c.Descriptors, nil
}
// DiscoverCharacteristics finds all the characteristics within a service. [Vol 3, Part G, 4.6.1]
// If filter is specified, only filtered characteristics are returned.
func (p *Client) DiscoverCharacteristics(filter []ble.UUID, s *ble.Service) ([]*ble.Characteristic, error) {
p.Lock()
defer p.Unlock()
start := s.Handle
var lastChar *ble.Characteristic
for start <= s.EndHandle {
length, b, err := p.ac.ReadByType(start, s.EndHandle, ble.CharacteristicUUID)
if err == ble.ErrAttrNotFound {
break
} else if err != nil {
return nil, err
}
for len(b) != 0 {
h := binary.LittleEndian.Uint16(b[:2])
p := ble.Property(b[2])
vh := binary.LittleEndian.Uint16(b[3:5])
u := ble.UUID(b[5:length])
c := &ble.Characteristic{
UUID: u,
Property: p,
Handle: h,
ValueHandle: vh,
EndHandle: s.EndHandle,
}
if filter == nil || ble.Contains(filter, u) {
s.Characteristics = append(s.Characteristics, c)
}
if lastChar != nil {
lastChar.EndHandle = c.Handle - 1
}
lastChar = c
start = vh + 1
b = b[length:]
}
}
return s.Characteristics, nil
}
// DiscoverDescriptors finds all the descriptors within a characteristic. [Vol 3, Part G, 4.7.1]
// If filter is specified, only filtered descriptors are returned.
func (cln *Client) DiscoverDescriptors(ds []ble.UUID, c *ble.Characteristic) ([]*ble.Descriptor, error) {
rsp := cln.conn.sendReq(70, xpc.Dict{
"kCBMsgArgDeviceUUID": cln.id,
"kCBMsgArgCharacteristicHandle": c.Handle,
"kCBMsgArgCharacteristicValueHandle": c.ValueHandle,
"kCBMsgArgUUIDs": uuidSlice(ds),
})
for _, xds := range rsp.descriptors() {
xd := msg(xds.(xpc.Dict))
c.Descriptors = append(c.Descriptors, &ble.Descriptor{
UUID: ble.MustParse(xd.uuid()),
Handle: uint16(xd.descriptorHandle()),
})
}
return c.Descriptors, nil
}