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fix(screencapture): USB discovery/activation robustness (infinite retry loop, fatal-on-close, handle leak, Linux --udid) #164

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fix(screencapture): USB discovery/activation robustness (infinite retry loop, fatal-on-close, handle leak, Linux --udid) #164

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74 changes: 41 additions & 33 deletions screencapture/activator.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -37,51 +37,59 @@ func EnableQTConfig(device IosDevice) (IosDevice, error) {
time.Sleep(500 * time.Millisecond)
log.Debug("Reopening Context")
ctx = gousb.NewContext()
device, err = device.ReOpen(ctx)
if err != nil {
log.Debugf("device not found:%s", err)
continue
}

// Count every attempt, including failures. Previously i++ and this cap
// sat after the `continue` below, so a persistently failing ReOpen never
// incremented i and the loop spun forever (500ms/iter) holding the
// device. Bound the retries here, before the failure `continue`.
i++
if i > 10 {
log.Debug("Failed activating config")
if cerr := ctx.Close(); cerr != nil {
log.Warnf("failed closing context on give-up: %v", cerr)
}
return IosDevice{}, fmt.Errorf("could not activate Quicktime Config for %s", usbSerial)
}

device, err = device.ReOpen(ctx)
if err != nil {
log.Debugf("device not found:%s", err)
continue
}
break
}
log.Debugf("QTConfig for %s activated", usbSerial)
return device, err
}

func DisableQTConfig(device IosDevice) (IosDevice, error) {
usbSerial := device.SerialNumber
ctx := gousb.NewContext()
usbDevice, err := OpenDevice(ctx, device)
if err != nil {
return IosDevice{}, err
}
if !isValidIosDeviceWithActiveQTConfig(usbDevice.Desc) {
log.Debugf("Skipping %s because it is already deactivated", usbSerial)
return device, nil
}

confignum, _ := usbDevice.ActiveConfigNum()
log.Debugf("Config is active: %d, QT config is: %d", confignum, device.QTConfigIndex)

for i := 0; i < 20; i++{
sendQTDisableConfigControlRequest(usbDevice)
log.Debugf("Resetting device config (#%d)", i + 1)
_, err := usbDevice.Config(device.UsbMuxConfigIndex)
if err != nil {
log.Warn(err)
}
}

confignum, _ = usbDevice.ActiveConfigNum()
log.Debugf("Config is active: %d, QT config is: %d", confignum, device.QTConfigIndex)


return device, err
usbSerial := device.SerialNumber
ctx := gousb.NewContext()
usbDevice, err := OpenDevice(ctx, device)
if err != nil {
return IosDevice{}, err
}
if !isValidIosDeviceWithActiveQTConfig(usbDevice.Desc) {
log.Debugf("Skipping %s because it is already deactivated", usbSerial)
return device, nil
}

confignum, _ := usbDevice.ActiveConfigNum()
log.Debugf("Config is active: %d, QT config is: %d", confignum, device.QTConfigIndex)

for i := 0; i < 20; i++ {
sendQTDisableConfigControlRequest(usbDevice)
log.Debugf("Resetting device config (#%d)", i+1)
_, err := usbDevice.Config(device.UsbMuxConfigIndex)
if err != nil {
log.Warn(err)
}
}

confignum, _ = usbDevice.ActiveConfigNum()
log.Debugf("Config is active: %d, QT config is: %d", confignum, device.QTConfigIndex)

return device, err
}

func sendQTConfigControlRequest(device *gousb.Device) {
Expand Down
60 changes: 36 additions & 24 deletions screencapture/discovery.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@ import (
log "github.com/sirupsen/logrus"
)

//IosDevice contains a gousb.Device pointer for a found device and some additional info like the device usbSerial
// IosDevice contains a gousb.Device pointer for a found device and some additional info like the device usbSerial
type IosDevice struct {
SerialNumber string
ProductName string
Expand All @@ -20,8 +20,8 @@ type IosDevice struct {
UsbInfo string
}

//OpenDevice finds a gousb.Device by using the provided iosDevice.SerialNumber. It returns an open device handle.
//Opening using VID and PID is not specific enough, as different iOS devices can have identical VID/PID combinations.
// OpenDevice finds a gousb.Device by using the provided iosDevice.SerialNumber. It returns an open device handle.
// Opening using VID and PID is not specific enough, as different iOS devices can have identical VID/PID combinations.
func OpenDevice(ctx *gousb.Context, iosDevice IosDevice) (*gousb.Device, error) {
deviceList, err := ctx.OpenDevices(func(desc *gousb.DeviceDesc) bool {
return true
Expand Down Expand Up @@ -49,7 +49,7 @@ func OpenDevice(ctx *gousb.Context, iosDevice IosDevice) (*gousb.Device, error)
return usbDevice, nil
}

//ReOpen creates a new Ios device, opening it using VID and PID, using the given context
// ReOpen creates a new Ios device, opening it using VID and PID, using the given context
func (d IosDevice) ReOpen(ctx *gousb.Context) (IosDevice, error) {

dev, err := OpenDevice(ctx, d)
Expand Down Expand Up @@ -82,9 +82,11 @@ func createContext() (*gousb.Context, func()) {
ctx := gousb.NewContext()
log.Debugf("Opened usbcontext:%v", ctx)
cleanUp := func() {
err := ctx.Close()
if err != nil {
log.Fatalf("Error closing usb context: %v", ctx)
if err := ctx.Close(); err != nil {
// A USB context-close error (e.g. a device handle still settling)
// must not kill the whole process. This used to be log.Fatalf,
// which called os.Exit and tore down the live video stream.
log.Warnf("Error closing usb context: %v", err)
}
}
return ctx, cleanUp
Expand All @@ -106,7 +108,11 @@ func FindIosDevice(usbSerial string) (IosDevice, error) {
return list[0], nil
}
for _, device := range list {
if usbSerial == device.SerialNumber {
// macOS libusb NUL-pads 24-character serials (iPhone Xr/Xs and newer) to
// 40 bytes; Linux libusb returns them bare. ValidateUdid emits the padded
// form, so a direct == misses the device on Linux — trim the padding on
// both sides so the --udid match works regardless of host OS.
if strings.Trim(usbSerial, "\x00") == strings.Trim(device.SerialNumber, "\x00") {
return device, nil
}
}
Expand All @@ -131,6 +137,15 @@ func findIosDevices(ctx *gousb.Context, validDeviceChecker func(desc *gousb.Devi
}

func mapToIosDevice(devices []*gousb.Device) ([]IosDevice, error) {
// Close every opened handle on all return paths. Previously a device was
// only closed on the happy path, so a transient SerialNumber()/Product()
// read error (common under USB contention) leaked the handle, which then
// made the deferred ctx.Close() fail — and that close was a log.Fatalf.
defer func() {
for _, d := range devices {
d.Close()
}
}()
iosDevices := make([]IosDevice, len(devices))
for i, d := range devices {
log.Debugf("Getting serial for: %s", d.String())
Expand All @@ -145,15 +160,12 @@ func mapToIosDevice(devices []*gousb.Device) ([]IosDevice, error) {
}

muxConfigIndex, qtConfigIndex := findConfigurations(d.Desc)
iosDevice := IosDevice{serial, product, muxConfigIndex, qtConfigIndex, d.Desc.Vendor, d.Desc.Product, d.String()}
d.Close()
iosDevices[i] = iosDevice

iosDevices[i] = IosDevice{serial, product, muxConfigIndex, qtConfigIndex, d.Desc.Vendor, d.Desc.Product, d.String()}
}
return iosDevices, nil
}

//PrintDeviceDetails returns a list of device details ready to be JSON converted.
// PrintDeviceDetails returns a list of device details ready to be JSON converted.
func PrintDeviceDetails(devices []IosDevice) []map[string]interface{} {
result := make([]map[string]interface{}, len(devices))
for k, device := range devices {
Expand Down Expand Up @@ -219,12 +231,12 @@ func findInterfaceForSubclass(confDesc gousb.ConfigDesc, subClass gousb.Class) (
return false, -1
}

//IsActivated returns a boolean that is true when this device was enabled for screen mirroring and false otherwise.
// IsActivated returns a boolean that is true when this device was enabled for screen mirroring and false otherwise.
func (d *IosDevice) IsActivated() bool {
return d.QTConfigIndex != -1
}

//DetailsMap contains all the info for a device in a map ready to be JSON encoded
// DetailsMap contains all the info for a device in a map ready to be JSON encoded
func (d *IosDevice) DetailsMap() map[string]interface{} {
return map[string]interface{}{
"deviceName": d.ProductName,
Expand All @@ -234,10 +246,10 @@ func (d *IosDevice) DetailsMap() map[string]interface{} {
}
}

//Usually iosDevices have a 40 character USB serial which equals the usbSerial used in usbmuxd, Xcode etc.
//There is an exception, some devices like the Xr and Xs have a 24 character USB serial. Usbmux, Xcode etc.
//however insert a dash after the 8th character in this case. To be compatible with other MacOS X and iOS tools,
//we insert the dash here as well.
// Usually iosDevices have a 40 character USB serial which equals the usbSerial used in usbmuxd, Xcode etc.
// There is an exception, some devices like the Xr and Xs have a 24 character USB serial. Usbmux, Xcode etc.
// however insert a dash after the 8th character in this case. To be compatible with other MacOS X and iOS tools,
// we insert the dash here as well.
func Correct24CharacterSerial(usbSerial string) string {
usbSerial = strings.Trim(usbSerial, "\x00")
if len(usbSerial) == 24 {
Expand All @@ -248,11 +260,11 @@ func Correct24CharacterSerial(usbSerial string) string {

const sixteenTimesZero = "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"

//ValidateUdid checks if a given udid is 25 or 40 characters long.
//25 character udids must be of format xxxxxxxx-xxxxxxxxxxxxxxxx.
//Serialnumbers on the usb host contain no dashes. As a convenience ValidateUdid
//returns the udid with the dash removed so it can be used
//as a correct USB SerialNumber.
// ValidateUdid checks if a given udid is 25 or 40 characters long.
// 25 character udids must be of format xxxxxxxx-xxxxxxxxxxxxxxxx.
// Serialnumbers on the usb host contain no dashes. As a convenience ValidateUdid
// returns the udid with the dash removed so it can be used
// as a correct USB SerialNumber.
func ValidateUdid(udid string) (string, error) {
udidLength := len(udid)
if !(udidLength == 25 || udidLength == 40) {
Expand Down