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package gatt
import (
"bytes"
"encoding/binary"
"errors"
"fmt"
"io"
"log"
"net"
"strings"
"github.com/paypal/gatt/linux"
)
type peripheral struct {
// NameChanged is called whenever the peripheral GAP device name has changed.
NameChanged func(*peripheral)
// ServicedModified is called when one or more service of a peripheral have changed.
// A list of invalid service is provided in the parameter.
ServicesModified func(*peripheral, []*Service)
d *device
svcs []*Service
sub *subscriber
mtu uint16
l2c io.ReadWriteCloser
reqc chan message
quitc chan struct{}
pd *linux.PlatData // platform specific data
}
func (p *peripheral) Device() Device { return p.d }
func (p *peripheral) ID() string { return strings.ToUpper(net.HardwareAddr(p.pd.Address[:]).String()) }
func (p *peripheral) Name() string { return p.pd.Name }
func (p *peripheral) Services() []*Service { return p.svcs }
func finish(op byte, h uint16, b []byte) bool {
done := b[0] == attOpError && b[1] == op && b[2] == byte(h) && b[3] == byte(h>>8)
e := attEcode(b[4])
if e != attEcodeAttrNotFound {
// log.Printf("unexpected protocol error: %s", e)
// FIXME: terminate the connection
}
return done
}
func (p *peripheral) DiscoverServices(s []UUID) ([]*Service, error) {
// TODO: implement the UUID filters
// p.pd.Conn.Write([]byte{0x02, 0x87, 0x00}) // MTU
done := false
start := uint16(0x0001)
for !done {
op := byte(attOpReadByGroupReq)
b := make([]byte, 7)
b[0] = op
binary.LittleEndian.PutUint16(b[1:3], start)
binary.LittleEndian.PutUint16(b[3:5], 0xFFFF)
binary.LittleEndian.PutUint16(b[5:7], 0x2800)
b = p.sendReq(op, b)
if finish(op, start, b) {
break
}
b = b[1:]
l, b := int(b[0]), b[1:]
switch {
case l == 6 && (len(b)%6 == 0):
case l == 20 && (len(b)%20 == 0):
default:
return nil, ErrInvalidLength
}
for len(b) != 0 {
h := binary.LittleEndian.Uint16(b[:2])
endh := binary.LittleEndian.Uint16(b[2:4])
s := &Service{
uuid: UUID{b[4:l]},
h: h,
endh: endh,
}
p.svcs = append(p.svcs, s)
b = b[l:]
done = endh == 0xFFFF
start = endh + 1
}
}
return p.svcs, nil
}
func (p *peripheral) DiscoverIncludedServices(ss []UUID, s *Service) ([]*Service, error) {
// TODO
return nil, nil
}
func (p *peripheral) DiscoverCharacteristics(cs []UUID, s *Service) ([]*Characteristic, error) {
// TODO: implement the UUID filters
done := false
start := s.h
var prev *Characteristic
for !done {
op := byte(attOpReadByTypeReq)
b := make([]byte, 7)
b[0] = op
binary.LittleEndian.PutUint16(b[1:3], start)
binary.LittleEndian.PutUint16(b[3:5], s.endh)
binary.LittleEndian.PutUint16(b[5:7], 0x2803)
b = p.sendReq(op, b)
if finish(op, start, b) {
break
}
b = b[1:]
l, b := int(b[0]), b[1:]
switch {
case l == 7 && (len(b)%7 == 0):
case l == 21 && (len(b)%21 == 0):
default:
return nil, ErrInvalidLength
}
for len(b) != 0 {
h := binary.LittleEndian.Uint16(b[:2])
props := Property(b[2])
vh := binary.LittleEndian.Uint16(b[3:5])
u := UUID{b[5:l]}
s := searchService(p.svcs, h, vh)
if s == nil {
log.Printf("Can't find service range that contains 0x%04X - 0x%04X", h, vh)
return nil, fmt.Errorf("Can't find service range that contains 0x%04X - 0x%04X", h, vh)
}
c := &Characteristic{
uuid: u,
svc: s,
props: props,
h: h,
vh: vh,
}
s.chars = append(s.chars, c)
b = b[l:]
done = vh == s.endh
start = vh + 1
if prev != nil {
prev.endh = c.h - 1
}
prev = c
}
}
if len(s.chars) > 1 {
s.chars[len(s.chars)-1].endh = s.endh
}
return s.chars, nil
}
func (p *peripheral) DiscoverDescriptors(ds []UUID, c *Characteristic) ([]*Descriptor, error) {
// TODO: implement the UUID filters
done := false
start := c.vh + 1
for !done {
if c.endh == 0 {
c.endh = c.svc.endh
}
op := byte(attOpFindInfoReq)
b := make([]byte, 5)
b[0] = op
binary.LittleEndian.PutUint16(b[1:3], start)
binary.LittleEndian.PutUint16(b[3:5], c.endh)
b = p.sendReq(op, b)
if finish(attOpFindInfoReq, start, b) {
break
}
b = b[1:]
var l int
f, b := int(b[0]), b[1:]
switch {
case f == 1 && (len(b)%4 == 0):
l = 4
case f == 2 && (len(b)%18 == 0):
l = 18
default:
return nil, ErrInvalidLength
}
for len(b) != 0 {
h := binary.LittleEndian.Uint16(b[:2])
u := UUID{b[2:l]}
d := &Descriptor{uuid: u, h: h, char: c}
c.descs = append(c.descs, d)
if u.Equal(attrClientCharacteristicConfigUUID) {
c.cccd = d
}
b = b[l:]
done = h == c.endh
start = h + 1
}
}
return c.descs, nil
}
func (p *peripheral) ReadCharacteristic(c *Characteristic) ([]byte, error) {
b := make([]byte, 3)
op := byte(attOpReadReq)
b[0] = op
binary.LittleEndian.PutUint16(b[1:3], c.vh)
b = p.sendReq(op, b)
b = b[1:]
return b, nil
}
func (p *peripheral) ReadLongCharacteristic(c *Characteristic) ([]byte, error) {
// The spec says that a read blob request should fail if the characteristic
// is smaller than mtu - 1. To simplify the API, the first read is done
// with a regular read request. If the buffer received is equal to mtu -1,
// then we read the rest of the data using read blob.
firstRead, err := p.ReadCharacteristic(c)
if err != nil {
return nil, err
}
if len(firstRead) < int(p.mtu)-1 {
return firstRead, nil
}
var buf bytes.Buffer
buf.Write(firstRead)
off := uint16(len(firstRead))
for {
b := make([]byte, 5)
op := byte(attOpReadBlobReq)
b[0] = op
binary.LittleEndian.PutUint16(b[1:3], c.vh)
binary.LittleEndian.PutUint16(b[3:5], off)
b = p.sendReq(op, b)
b = b[1:]
if len(b) == 0 {
break
}
buf.Write(b)
off += uint16(len(b))
if len(b) < int(p.mtu)-1 {
break
}
}
return buf.Bytes(), nil
}
func (p *peripheral) WriteCharacteristic(c *Characteristic, value []byte, noRsp bool) error {
b := make([]byte, 3+len(value))
op := byte(attOpWriteReq)
b[0] = op
if noRsp {
b[0] = attOpWriteCmd
}
binary.LittleEndian.PutUint16(b[1:3], c.vh)
copy(b[3:], value)
if noRsp {
p.sendCmd(op, b)
return nil
}
b = p.sendReq(op, b)
// TODO: error handling
b = b[1:]
return nil
}
func (p *peripheral) ReadDescriptor(d *Descriptor) ([]byte, error) {
b := make([]byte, 3)
op := byte(attOpReadReq)
b[0] = op
binary.LittleEndian.PutUint16(b[1:3], d.h)
b = p.sendReq(op, b)
b = b[1:]
// TODO: error handling
return b, nil
}
func (p *peripheral) WriteDescriptor(d *Descriptor, value []byte) error {
b := make([]byte, 3+len(value))
op := byte(attOpWriteReq)
b[0] = op
binary.LittleEndian.PutUint16(b[1:3], d.h)
copy(b[3:], value)
b = p.sendReq(op, b)
b = b[1:]
// TODO: error handling
return nil
}
func (p *peripheral) setNotifyValue(c *Characteristic, flag uint16,
f func(*Characteristic, []byte, error)) error {
if c.cccd == nil {
return errors.New("no cccd") // FIXME
}
ccc := uint16(0)
if f != nil {
ccc = flag
p.sub.subscribe(c.vh, func(b []byte, err error) { f(c, b, err) })
}
b := make([]byte, 5)
op := byte(attOpWriteReq)
b[0] = op
binary.LittleEndian.PutUint16(b[1:3], c.cccd.h)
binary.LittleEndian.PutUint16(b[3:5], ccc)
b = p.sendReq(op, b)
b = b[1:]
// TODO: error handling
if f == nil {
p.sub.unsubscribe(c.vh)
}
return nil
}
func (p *peripheral) SetNotifyValue(c *Characteristic,
f func(*Characteristic, []byte, error)) error {
return p.setNotifyValue(c, gattCCCNotifyFlag, f)
}
func (p *peripheral) SetIndicateValue(c *Characteristic,
f func(*Characteristic, []byte, error)) error {
return p.setNotifyValue(c, gattCCCIndicateFlag, f)
}
func (p *peripheral) ReadRSSI() int {
// TODO: implement
return -1
}
func searchService(ss []*Service, start, end uint16) *Service {
for _, s := range ss {
if s.h < start && s.endh >= end {
return s
}
}
return nil
}
// TODO: unifiy the message with OS X pots and refactor
type message struct {
op byte
b []byte
rspc chan []byte
}
func (p *peripheral) sendCmd(op byte, b []byte) {
p.reqc <- message{op: op, b: b}
}
func (p *peripheral) sendReq(op byte, b []byte) []byte {
m := message{op: op, b: b, rspc: make(chan []byte)}
p.reqc <- m
return <-m.rspc
}
func (p *peripheral) loop() {
// Serialize the request.
rspc := make(chan []byte)
// Dequeue request loop
go func() {
for {
select {
case req := <-p.reqc:
p.l2c.Write(req.b)
if req.rspc == nil {
break
}
r := <-rspc
switch reqOp, rspOp := req.b[0], r[0]; {
case rspOp == attRspFor[reqOp]:
case rspOp == attOpError && r[1] == reqOp:
default:
log.Printf("Request 0x%02x got a mismatched response: 0x%02x", reqOp, rspOp)
// FIXME: terminate the connection?
}
req.rspc <- r
case <-p.quitc:
return
}
}
}()
// L2CAP implementations shall support a minimum MTU size of 48 bytes.
// The default value is 672 bytes
buf := make([]byte, 672)
// Handling response or notification/indication
for {
n, err := p.l2c.Read(buf)
if n == 0 || err != nil {
close(p.quitc)
return
}
b := make([]byte, n)
copy(b, buf)
if (b[0] != attOpHandleNotify) && (b[0] != attOpHandleInd) {
rspc <- b
continue
}
h := binary.LittleEndian.Uint16(b[1:3])
f := p.sub.fn(h)
if f == nil {
log.Printf("notified by unsubscribed handle")
// FIXME: terminate the connection?
} else {
go f(b[3:], nil)
}
if b[0] == attOpHandleInd {
// write aknowledgement for indication
p.l2c.Write([]byte{attOpHandleCnf})
}
}
}
func (p *peripheral) SetMTU(mtu uint16) error {
b := make([]byte, 3)
op := byte(attOpMtuReq)
b[0] = op
binary.LittleEndian.PutUint16(b[1:3], uint16(mtu))
b = p.sendReq(op, b)
serverMTU := binary.LittleEndian.Uint16(b[1:3])
if serverMTU < mtu {
mtu = serverMTU
}
p.mtu = mtu
return nil
}
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