forked from weaveworks/weave
/
mac_cache.go
133 lines (112 loc) · 2.58 KB
/
mac_cache.go
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package router
import (
"net"
"sync"
"time"
"github.com/weaveworks/mesh"
)
type MacCacheEntry struct {
lastSeen time.Time
peer *mesh.Peer
}
type MacCache struct {
sync.RWMutex
table map[uint64]*MacCacheEntry
maxAge time.Duration
expiryTimer *time.Timer
onExpiry func(net.HardwareAddr, *mesh.Peer)
}
func NewMacCache(maxAge time.Duration, onExpiry func(net.HardwareAddr, *mesh.Peer)) *MacCache {
cache := &MacCache{
table: make(map[uint64]*MacCacheEntry),
maxAge: maxAge,
onExpiry: onExpiry}
cache.setExpiryTimer()
return cache
}
func (cache *MacCache) add(mac net.HardwareAddr, peer *mesh.Peer, force bool) (bool, *mesh.Peer) {
key := macint(mac)
now := time.Now()
cache.RLock()
entry, found := cache.table[key]
if found && entry.peer == peer && now.Before(entry.lastSeen.Add(cache.maxAge/10)) {
cache.RUnlock()
return false, nil
}
cache.RUnlock()
cache.Lock()
defer cache.Unlock()
entry, found = cache.table[key]
if !found {
cache.table[key] = &MacCacheEntry{lastSeen: now, peer: peer}
return true, nil
}
if entry.peer != peer {
if !force {
return false, entry.peer
}
entry.peer = peer
}
if now.After(entry.lastSeen.Add(cache.maxAge / 10)) {
entry.lastSeen = now
}
return false, nil
}
func (cache *MacCache) Add(mac net.HardwareAddr, peer *mesh.Peer) (bool, *mesh.Peer) {
return cache.add(mac, peer, false)
}
func (cache *MacCache) AddForced(mac net.HardwareAddr, peer *mesh.Peer) (bool, *mesh.Peer) {
return cache.add(mac, peer, true)
}
func (cache *MacCache) Lookup(mac net.HardwareAddr) *mesh.Peer {
key := macint(mac)
cache.RLock()
defer cache.RUnlock()
entry, found := cache.table[key]
if !found {
return nil
}
return entry.peer
}
func (cache *MacCache) Delete(peer *mesh.Peer) bool {
found := false
cache.Lock()
defer cache.Unlock()
for key, entry := range cache.table {
if entry.peer == peer {
delete(cache.table, key)
found = true
}
}
return found
}
func (cache *MacCache) setExpiryTimer() {
cache.expiryTimer = time.AfterFunc(cache.maxAge/10, func() { cache.expire() })
}
func (cache *MacCache) expire() {
now := time.Now()
cache.Lock()
defer cache.Unlock()
for key, entry := range cache.table {
if now.After(entry.lastSeen.Add(cache.maxAge)) {
delete(cache.table, key)
cache.onExpiry(intmac(key), entry.peer)
}
}
cache.setExpiryTimer()
}
func macint(mac net.HardwareAddr) (r uint64) {
for _, b := range mac {
r <<= 8
r |= uint64(b)
}
return
}
func intmac(key uint64) (r net.HardwareAddr) {
r = make([]byte, 6)
for i := 5; i >= 0; i-- {
r[i] = byte(key)
key >>= 8
}
return
}