AdGuardHome/internal/dhcpsvc/leaseindex.go

142 lines
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package dhcpsvc
import (
"fmt"
"net/netip"
"slices"
"strings"
)
// leaseIndex is the set of leases indexed by their identifiers for quick
// lookup.
type leaseIndex struct {
// byAddr is a lookup shortcut for leases by their IP addresses.
byAddr map[netip.Addr]*Lease
// byName is a lookup shortcut for leases by their hostnames.
//
// TODO(e.burkov): Use a slice of leases with the same hostname?
byName map[string]*Lease
}
// newLeaseIndex returns a new index for [Lease]s.
func newLeaseIndex() *leaseIndex {
return &leaseIndex{
byAddr: map[netip.Addr]*Lease{},
byName: map[string]*Lease{},
}
}
// leaseByAddr returns a lease by its IP address.
func (idx *leaseIndex) leaseByAddr(addr netip.Addr) (l *Lease, ok bool) {
l, ok = idx.byAddr[addr]
return l, ok
}
// leaseByName returns a lease by its hostname.
func (idx *leaseIndex) leaseByName(name string) (l *Lease, ok bool) {
// TODO(e.burkov): Probably, use a case-insensitive comparison and store in
// slice. This would require a benchmark.
l, ok = idx.byName[strings.ToLower(name)]
return l, ok
}
// clear removes all leases from idx.
func (idx *leaseIndex) clear() {
clear(idx.byAddr)
clear(idx.byName)
}
// add adds l into idx and into iface. l must be valid, iface should be
// responsible for l's IP. It returns an error if l duplicates at least a
// single value of another lease.
func (idx *leaseIndex) add(l *Lease, iface *netInterface) (err error) {
loweredName := strings.ToLower(l.Hostname)
if _, ok := idx.byAddr[l.IP]; ok {
return fmt.Errorf("lease for ip %s already exists", l.IP)
} else if _, ok = idx.byName[loweredName]; ok {
return fmt.Errorf("lease for hostname %s already exists", l.Hostname)
}
err = iface.addLease(l)
if err != nil {
return err
}
idx.byAddr[l.IP] = l
idx.byName[loweredName] = l
return nil
}
// remove removes l from idx and from iface. l must be valid, iface should
// contain the same lease or the lease itself. It returns an error if the lease
// not found.
func (idx *leaseIndex) remove(l *Lease, iface *netInterface) (err error) {
loweredName := strings.ToLower(l.Hostname)
if _, ok := idx.byAddr[l.IP]; !ok {
return fmt.Errorf("no lease for ip %s", l.IP)
} else if _, ok = idx.byName[loweredName]; !ok {
return fmt.Errorf("no lease for hostname %s", l.Hostname)
}
err = iface.removeLease(l)
if err != nil {
return err
}
delete(idx.byAddr, l.IP)
delete(idx.byName, loweredName)
return nil
}
// update updates l in idx and in iface. l must be valid, iface should be
// responsible for l's IP. It returns an error if l duplicates at least a
// single value of another lease, except for the updated lease itself.
func (idx *leaseIndex) update(l *Lease, iface *netInterface) (err error) {
loweredName := strings.ToLower(l.Hostname)
existing, ok := idx.byAddr[l.IP]
if ok && !slices.Equal(l.HWAddr, existing.HWAddr) {
return fmt.Errorf("lease for ip %s already exists", l.IP)
}
existing, ok = idx.byName[loweredName]
if ok && !slices.Equal(l.HWAddr, existing.HWAddr) {
return fmt.Errorf("lease for hostname %s already exists", l.Hostname)
}
prev, err := iface.updateLease(l)
if err != nil {
return err
}
delete(idx.byAddr, prev.IP)
delete(idx.byName, strings.ToLower(prev.Hostname))
idx.byAddr[l.IP] = l
idx.byName[loweredName] = l
return nil
}
// rangeLeases calls f for each lease in idx in an unspecified order until f
// returns false.
func (idx *leaseIndex) rangeLeases(f func(l *Lease) (cont bool)) {
for _, l := range idx.byName {
if !f(l) {
break
}
}
}
// len returns the number of leases in idx.
func (idx *leaseIndex) len() (l uint) {
return uint(len(idx.byAddr))
}