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gattc_hci.go
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gattc_hci.go
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//go:build hci || ninafw || cyw43439
package bluetooth
import "errors"
var (
errNotYetImplemented = errors.New("bluetooth: not yet implemented")
errNoWrite = errors.New("bluetooth: write not permitted")
errNoWriteWithoutResponse = errors.New("bluetooth: write without response not permitted")
errWriteFailed = errors.New("bluetooth: write failed")
errNoRead = errors.New("bluetooth: read not permitted")
errReadFailed = errors.New("bluetooth: read failed")
errNoNotify = errors.New("bluetooth: notify/indicate not permitted")
errEnableNotificationsFailed = errors.New("bluetooth: enable notifications failed")
errServiceNotFound = errors.New("bluetooth: service not found")
errCharacteristicNotFound = errors.New("bluetooth: characteristic not found")
)
const (
maxDefaultServicesToDiscover = 8
maxDefaultCharacteristicsToDiscover = 16
)
const (
charPropertyBroadcast = 0x01
charPropertyRead = 0x02
charPropertyWriteWithoutResponse = 0x04
charPropertyWrite = 0x08
charPropertyNotify = 0x10
charPropertyIndicate = 0x20
)
// DeviceService is a BLE service on a connected peripheral device.
type DeviceService struct {
uuid UUID
device Device
startHandle, endHandle uint16
}
// UUID returns the UUID for this DeviceService.
func (s DeviceService) UUID() UUID {
return s.uuid
}
// DiscoverServices starts a service discovery procedure. Pass a list of service
// UUIDs you are interested in to this function. Either a slice of all services
// is returned (of the same length as the requested UUIDs and in the same
// order), or if some services could not be discovered an error is returned.
//
// Passing a nil slice of UUIDs will return a complete list of
// services.
func (d Device) DiscoverServices(uuids []UUID) ([]DeviceService, error) {
if debug {
println("DiscoverServices")
}
services := make([]DeviceService, 0, maxDefaultServicesToDiscover)
foundServices := make(map[UUID]DeviceService)
cd, err := d.adapter.att.findConnectionData(d.handle)
if err != nil {
return nil, err
}
startHandle := uint16(0x0001)
endHandle := uint16(0xffff)
for endHandle == uint16(0xffff) {
err := d.adapter.att.readByGroupReq(d.handle, startHandle, endHandle, gattServiceUUID)
if err != nil {
return nil, err
}
if debug {
println("found services", len(cd.services))
}
if len(cd.services) == 0 {
break
}
for _, rawService := range cd.services {
if len(uuids) == 0 || rawService.uuid.isIn(uuids) {
foundServices[rawService.uuid] =
DeviceService{
device: d,
uuid: rawService.uuid,
startHandle: rawService.startHandle,
endHandle: rawService.endHandle,
}
}
startHandle = rawService.endHandle + 1
if startHandle == 0x0000 {
endHandle = 0x0000
}
}
// reset raw services
cd.services = []rawService{}
// did we find them all?
if len(foundServices) == len(uuids) {
break
}
}
switch {
case len(uuids) > 0:
// put into correct order
for _, uuid := range uuids {
s, ok := foundServices[uuid]
if !ok {
return nil, errServiceNotFound
}
services = append(services, s)
}
default:
for _, s := range foundServices {
services = append(services, s)
}
}
return services, nil
}
// DeviceCharacteristic is a BLE characteristic on a connected peripheral
// device.
type DeviceCharacteristic struct {
uuid UUID
service *DeviceService
permissions CharacteristicPermissions
handle uint16
properties uint8
callback func(buf []byte)
}
// UUID returns the UUID for this DeviceCharacteristic.
func (c DeviceCharacteristic) UUID() UUID {
return c.uuid
}
// DiscoverCharacteristics discovers characteristics in this service. Pass a
// list of characteristic UUIDs you are interested in to this function. Either a
// list of all requested services is returned, or if some services could not be
// discovered an error is returned. If there is no error, the characteristics
// slice has the same length as the UUID slice with characteristics in the same
// order in the slice as in the requested UUID list.
//
// Passing a nil slice of UUIDs will return a complete
// list of characteristics.
func (s DeviceService) DiscoverCharacteristics(uuids []UUID) ([]DeviceCharacteristic, error) {
if debug {
println("DiscoverCharacteristics")
}
characteristics := make([]DeviceCharacteristic, 0, maxDefaultCharacteristicsToDiscover)
foundCharacteristics := make(map[UUID]DeviceCharacteristic)
cd, err := s.device.adapter.att.findConnectionData(s.device.handle)
if err != nil {
return nil, err
}
startHandle := s.startHandle
endHandle := s.endHandle
for startHandle < endHandle {
err := s.device.adapter.att.readByTypeReq(s.device.handle, startHandle, endHandle, gattCharacteristicUUID)
switch {
case err == ErrATTOp:
opcode, _, errcode := s.device.adapter.att.lastError(s.device.handle)
if opcode == attOpReadByTypeReq && errcode == attErrorAttrNotFound {
// no characteristics found
break
}
case err != nil:
return nil, err
}
if debug {
println("found characteristics", len(cd.characteristics))
}
if len(cd.characteristics) == 0 {
break
}
for _, rawCharacteristic := range cd.characteristics {
if len(uuids) == 0 || rawCharacteristic.uuid.isIn(uuids) {
dc := DeviceCharacteristic{
service: &s,
uuid: rawCharacteristic.uuid,
handle: rawCharacteristic.valueHandle,
properties: rawCharacteristic.properties,
permissions: CharacteristicPermissions(rawCharacteristic.properties),
}
foundCharacteristics[rawCharacteristic.uuid] = dc
}
startHandle = rawCharacteristic.valueHandle + 1
}
// reset raw characteristics
cd.characteristics = []rawCharacteristic{}
// did we find them all?
if len(foundCharacteristics) == len(uuids) {
break
}
}
switch {
case len(uuids) > 0:
// put into correct order
for _, uuid := range uuids {
c, ok := foundCharacteristics[uuid]
if !ok {
return nil, errCharacteristicNotFound
}
characteristics = append(characteristics, c)
}
default:
for _, c := range foundCharacteristics {
characteristics = append(characteristics, c)
}
}
return characteristics, nil
}
// WriteWithoutResponse replaces the characteristic value with a new value. The
// call will return before all data has been written. A limited number of such
// writes can be in flight at any given time. This call is also known as a
// "write command" (as opposed to a write request).
func (c DeviceCharacteristic) WriteWithoutResponse(p []byte) (n int, err error) {
if !c.permissions.WriteWithoutResponse() {
return 0, errNoWriteWithoutResponse
}
err = c.service.device.adapter.att.writeCmd(c.service.device.handle, c.handle, p)
if err != nil {
return 0, err
}
return len(p), nil
}
// EnableNotifications enables notifications in the Client Characteristic
// Configuration Descriptor (CCCD). This means that most peripherals will send a
// notification with a new value every time the value of the characteristic
// changes.
//
// Users may call EnableNotifications with a nil callback to disable notifications.
func (c DeviceCharacteristic) EnableNotifications(callback func(buf []byte)) error {
if !c.permissions.Notify() {
return errNoNotify
}
switch {
case callback == nil:
// disable notifications
if debug {
println("disabling notifications")
}
err := c.service.device.adapter.att.writeReq(c.service.device.handle, c.handle+1, []byte{0x00, 0x00})
if err != nil {
return err
}
default:
// enable notifications
if debug {
println("enabling notifications")
}
err := c.service.device.adapter.att.writeReq(c.service.device.handle, c.handle+1, []byte{0x01, 0x00})
if err != nil {
return err
}
}
c.callback = callback
c.service.device.startNotifications()
c.service.device.addNotificationRegistration(c.handle, c.callback)
return nil
}
// GetMTU returns the MTU for the characteristic.
func (c DeviceCharacteristic) GetMTU() (uint16, error) {
err := c.service.device.adapter.att.mtuReq(c.service.device.handle)
if err != nil {
return 0, err
}
c.service.device.mtu = c.service.device.adapter.att.mtu
return c.service.device.mtu, nil
}
// Read reads the current characteristic value.
func (c DeviceCharacteristic) Read(data []byte) (int, error) {
if !c.permissions.Read() {
return 0, errNoRead
}
err := c.service.device.adapter.att.readReq(c.service.device.handle, c.handle)
if err != nil {
return 0, err
}
cd, err := c.service.device.adapter.att.findConnectionData(c.service.device.handle)
if err != nil {
return 0, err
}
if len(cd.value) == 0 {
return 0, errReadFailed
}
copy(data, cd.value)
return len(cd.value), nil
}