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udp.go
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udp.go
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package usb
import (
"bytes"
"fmt"
"io"
"net"
"strconv"
"strings"
"sync/atomic"
"time"
"github.com/trezor/trezord-go/core"
"github.com/trezor/trezord-go/memorywriter"
)
var emulatorPing = []byte("PINGPING")
var emulatorPong = []byte("PONGPONG")
const (
emulatorPrefix = "emulator"
emulatorAddress = "127.0.0.1"
emulatorPingTimeout = 1000 * time.Millisecond // it seems neither 500 nor 700 is enough for trezor-link
)
type udpLowlevel struct {
ping chan []byte
data chan []byte
writer io.Writer
}
type UDP struct {
ports []PortTouple
lowlevels map[int]*udpLowlevel
mw *memorywriter.MemoryWriter
}
func listen(conn io.Reader) (chan []byte, chan []byte) {
ping := make(chan []byte, 1)
data := make(chan []byte, 100)
go func() {
for {
buffer := make([]byte, 64)
_, err := conn.Read(buffer)
if err == nil {
first := buffer[0]
if first == '?' {
data <- buffer
}
if first == 'P' {
copied := make([]byte, 8)
copy(copied, buffer)
ping <- copied
}
}
}
}()
return ping, data
}
type PortTouple struct {
Normal int
Debug int // 0 if not present
}
func (udp *UDP) makeLowlevel(port int) error {
address := emulatorAddress + ":" + strconv.Itoa(port)
connection, err := net.Dial("udp", address)
if err != nil {
return err
}
ping, data := listen(connection)
udp.lowlevels[port] = &udpLowlevel{
ping: ping,
data: data,
writer: connection,
}
return nil
}
func InitUDP(ports []PortTouple, mw *memorywriter.MemoryWriter) (*UDP, error) {
udp := UDP{
ports: ports,
lowlevels: make(map[int](*udpLowlevel)),
mw: mw,
}
for _, port := range ports {
err := udp.makeLowlevel(port.Normal)
if err != nil {
return nil, err
}
if port.Debug != 0 {
err = udp.makeLowlevel(port.Debug)
if err != nil {
return nil, err
}
}
}
return &udp, nil
}
func checkPort(ping chan []byte, w io.Writer) (bool, error) {
_, err := w.Write(emulatorPing)
if err != nil {
return false, err
}
select {
case response := <-ping:
return bytes.Equal(response, emulatorPong), nil
case <-time.After(emulatorPingTimeout):
return false, nil
}
}
func (udp *UDP) Enumerate() ([]core.USBInfo, error) {
var infos []core.USBInfo
udp.mw.Log("checking ports")
for _, port := range udp.ports {
udp.mw.Log(fmt.Sprintf("check normal port %d", port.Normal))
normal := udp.lowlevels[port.Normal]
presentN, err := checkPort(normal.ping, normal.writer)
udp.mw.Log(fmt.Sprintf("check normal port res %t", presentN))
if err != nil {
return nil, err
}
if presentN {
presentD := false
if port.Debug != 0 {
debug := udp.lowlevels[port.Debug]
presentD, err = checkPort(debug.ping, debug.writer)
if err != nil {
return nil, err
}
}
info := core.USBInfo{
Path: emulatorPrefix + strconv.Itoa(port.Normal) + "D" + strconv.Itoa(port.Debug),
VendorID: 0,
ProductID: 0,
Type: core.TypeEmulator,
}
if presentD {
info.Debug = true
}
infos = append(infos, info)
}
}
return infos, nil
}
func (udp *UDP) Has(path string) bool {
return strings.HasPrefix(path, emulatorPrefix)
}
func (udp *UDP) Connect(path string, debug bool, reset bool) (core.USBDevice, error) {
ports := strings.Split(strings.TrimPrefix(path, emulatorPrefix), "D")
var port int
if debug {
debugP, err := strconv.Atoi(ports[1])
if err != nil {
return nil, err
}
if debugP == 0 {
return nil, errNotDebug
}
port = debugP
} else {
normalP, err := strconv.Atoi(ports[0])
if err != nil {
return nil, err
}
port = normalP
}
d := &UDPDevice{
lowlevel: udp.lowlevels[port],
}
return d, nil
}
func (udp *UDP) Close() {
// nothing
}
type UDPDevice struct {
lowlevel *udpLowlevel
closed int32 // atomic
}
func (d *UDPDevice) Close(disconnected bool) error {
atomic.StoreInt32(&d.closed, 1)
return nil
}
func (d *UDPDevice) readWrite(buf []byte, read bool) (int, error) {
lowlevel := d.lowlevel
for {
closed := (atomic.LoadInt32(&d.closed)) == 1
if closed {
return 0, errClosedDevice
}
check, err := checkPort(lowlevel.ping, lowlevel.writer)
if err != nil {
return 0, err
}
if !check {
return 0, errDisconnect
}
if !read {
return lowlevel.writer.Write(buf)
}
select {
case response := <-lowlevel.data:
copy(buf, response)
return len(response), nil
case <-time.After(emulatorPingTimeout):
// timeout, continue for cycle
}
}
}
func (d *UDPDevice) Write(buf []byte) (int, error) {
return d.readWrite(buf, false)
}
func (d *UDPDevice) Read(buf []byte) (int, error) {
return d.readWrite(buf, true)
}