129 lines
3.8 KiB
Go
129 lines
3.8 KiB
Go
//go:build hci || ninafw
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package bluetooth
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type Characteristic struct {
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adapter *Adapter
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handle uint16
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permissions CharacteristicPermissions
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value []byte
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cccd uint16
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}
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// AddService creates a new service with the characteristics listed in the
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// Service struct.
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func (a *Adapter) AddService(service *Service) error {
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uuid := service.UUID.Bytes()
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serviceHandle := a.att.addLocalAttribute(attributeTypeService, 0, shortUUID(gattServiceUUID).UUID(), 0, uuid[:])
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valueHandle := serviceHandle
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endHandle := serviceHandle
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for i := range service.Characteristics {
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data := service.Characteristics[i].UUID.Bytes()
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cuuid := append([]byte{}, data[:]...)
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// add characteristic declaration
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charHandle := a.att.addLocalAttribute(attributeTypeCharacteristic, serviceHandle, shortUUID(gattCharacteristicUUID).UUID(), CharacteristicReadPermission, cuuid[:])
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// add characteristic value
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vf := CharacteristicPermissions(0)
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if service.Characteristics[i].Flags.Read() {
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vf |= CharacteristicReadPermission
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}
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if service.Characteristics[i].Flags.Write() {
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vf |= CharacteristicWritePermission
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}
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valueHandle = a.att.addLocalAttribute(attributeTypeCharacteristicValue, charHandle, service.Characteristics[i].UUID, vf, service.Characteristics[i].Value)
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endHandle = valueHandle
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// add characteristic descriptor
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if service.Characteristics[i].Flags.Notify() ||
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service.Characteristics[i].Flags.Indicate() {
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endHandle = a.att.addLocalAttribute(attributeTypeDescriptor, charHandle, shortUUID(gattClientCharacteristicConfigUUID).UUID(), CharacteristicReadPermission|CharacteristicWritePermission, []byte{0, 0})
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}
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if service.Characteristics[i].Handle == nil {
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service.Characteristics[i].Handle = &Characteristic{}
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}
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service.Characteristics[i].Handle.adapter = a
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service.Characteristics[i].Handle.handle = valueHandle
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service.Characteristics[i].Handle.permissions = service.Characteristics[i].Flags
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if len(service.Characteristics[i].Value) > 0 {
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service.Characteristics[i].Handle.value = service.Characteristics[i].Value
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}
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if (service.Characteristics[i].Flags.Write() ||
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service.Characteristics[i].Flags.WriteWithoutResponse()) &&
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service.Characteristics[i].WriteEvent != nil {
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handlers := append(a.charWriteHandlers, charWriteHandler{
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handle: valueHandle,
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callback: service.Characteristics[i].WriteEvent,
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})
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a.charWriteHandlers = handlers
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}
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if debug {
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println("added characteristic", charHandle, valueHandle, service.Characteristics[i].UUID.String())
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}
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a.att.addLocalCharacteristic(charHandle, service.Characteristics[i].Flags, valueHandle, service.Characteristics[i].UUID, service.Characteristics[i].Handle)
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}
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if debug {
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println("added service", serviceHandle, endHandle, service.UUID.String())
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}
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a.att.addLocalService(serviceHandle, endHandle, service.UUID)
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return nil
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}
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// Write replaces the characteristic value with a new value.
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func (c *Characteristic) Write(p []byte) (n int, err error) {
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if !(c.permissions.Write() || c.permissions.WriteWithoutResponse() ||
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c.permissions.Notify() || c.permissions.Indicate()) {
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return 0, errNoWrite
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}
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hdl := c.adapter.getCharWriteHandler(c.handle)
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if hdl != nil {
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hdl.callback(Connection(c.handle), 0, p)
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}
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copy(c.value, p)
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if c.cccd&0x01 != 0 {
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// send notification
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c.adapter.att.sendNotification(c.handle, c.value)
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}
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return len(c.value), nil
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}
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func (c *Characteristic) readCCCD() (uint16, error) {
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if !c.permissions.Notify() {
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return 0, errNoNotify
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}
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return c.cccd, nil
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}
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func (c *Characteristic) writeCCCD(val uint16) error {
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if !c.permissions.Notify() {
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return errNoNotify
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}
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c.cccd = val
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return nil
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}
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func (c *Characteristic) readValue() ([]byte, error) {
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if !c.permissions.Read() {
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return nil, errNoRead
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}
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return c.value, nil
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}
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