package firewall import ( "sync/atomic" "time" "github.com/sirupsen/logrus" ) // ConntrackCache is used as a local routine cache to know if a given flow // has been seen in the conntrack table. type ConntrackCache map[Packet]struct{} type ConntrackCacheTicker struct { cacheV uint64 cacheTick atomic.Uint64 cache ConntrackCache } func NewConntrackCacheTicker(d time.Duration) *ConntrackCacheTicker { if d == 0 { return nil } c := &ConntrackCacheTicker{ cache: ConntrackCache{}, } go c.tick(d) return c } func (c *ConntrackCacheTicker) tick(d time.Duration) { for { time.Sleep(d) c.cacheTick.Add(1) } } // Get checks if the cache ticker has moved to the next version before returning // the map. If it has moved, we reset the map. func (c *ConntrackCacheTicker) Get(l *logrus.Logger) ConntrackCache { if c == nil { return nil } if tick := c.cacheTick.Load(); tick != c.cacheV { c.cacheV = tick if ll := len(c.cache); ll > 0 { if l.Level == logrus.DebugLevel { l.WithField("len", ll).Debug("resetting conntrack cache") } c.cache = make(ConntrackCache, ll) } } return c.cache }