func (a *Allocator) getAddress(subnet *net.IPNet, bitmask *bitseq.Handle, prefAddress net.IP, ver ipVersion) (net.IP, error) {
var (
bytePos, bitPos int
ordinal int
err error
)
// Look for free IP, skip .0 and .255, they will be automatically reserved
for {
if bitmask.Unselected() <= 0 {
return nil, ErrNoAvailableIPs
}
if prefAddress == nil {
bytePos, bitPos, err = bitmask.GetFirstAvailable()
} else {
ordinal = ipToInt(getHostPortionIP(prefAddress, subnet))
bytePos, bitPos, err = bitmask.CheckIfAvailable(ordinal)
}
if err != nil {
return nil, ErrNoAvailableIPs
}
// Lock it
if err = bitmask.PushReservation(bytePos, bitPos, false); err != nil {
if _, ok := err.(types.RetryError); !ok {
return nil, fmt.Errorf("internal failure while reserving the address: %s", err.Error())
}
continue
}
// Build IP ordinal
ordinal = bitPos + bytePos*8
// For v4, let reservation of .0 and .255 happen automatically
if ver == v4 && !isValidIP(ordinal) {
continue
}
break
}
// Convert IP ordinal for this subnet into IP address
return generateAddress(ordinal, subnet), nil
}
