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package water
import (
"os"
"strings"
"syscall"
"unsafe"
)
const (
cIFFTUN = 0x0001
cIFFTAP = 0x0002
cIFFNOPI = 0x1000
cIFFMULTIQUEUE = 0x0100
)
type ifReq struct {
Name [0x10]byte
Flags uint16
pad [0x28 - 0x10 - 2]byte
}
func ioctl(fd uintptr, request uintptr, argp uintptr) error {
_, _, errno := syscall.Syscall(syscall.SYS_IOCTL, fd, uintptr(request), argp)
if errno != 0 {
return os.NewSyscallError("ioctl", errno)
}
return nil
}
func setupFd(config Config, fd uintptr) (name string, err error) {
var flags uint16 = cIFFNOPI
if config.DeviceType == TUN {
flags |= cIFFTUN
} else {
flags |= cIFFTAP
}
if config.PlatformSpecificParams.MultiQueue {
flags |= cIFFMULTIQUEUE
}
if name, err = createInterface(fd, config.Name, flags); err != nil {
return "", err
}
if err = setDeviceOptions(fd, config); err != nil {
return "", err
}
return name, nil
}
func createInterface(fd uintptr, ifName string, flags uint16) (createdIFName string, err error) {
var req ifReq
req.Flags = flags
copy(req.Name[:], ifName)
err = ioctl(fd, syscall.TUNSETIFF, uintptr(unsafe.Pointer(&req)))
if err != nil {
return
}
createdIFName = strings.Trim(string(req.Name[:]), "\x00")
return
}
func setDeviceOptions(fd uintptr, config Config) (err error) {
if config.Permissions != nil {
if err = ioctl(fd, syscall.TUNSETOWNER, uintptr(config.Permissions.Owner)); err != nil {
return
}
if err = ioctl(fd, syscall.TUNSETGROUP, uintptr(config.Permissions.Group)); err != nil {
return
}
}
// set clear the persist flag
value := 0
if config.Persist {
value = 1
}
return ioctl(fd, syscall.TUNSETPERSIST, uintptr(value))
}
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