route/vendor/github.com/xtaci/kcp-go/blacklist.go

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2018-01-03 19:19:49 +00:00
package kcp
import (
"sync"
"time"
)
var (
// BlacklistDuration sets a duration for which a session is blacklisted
// once it's established. This is simillar to TIME_WAIT state in TCP, whereby
// any connection attempt with the same session parameters is ignored for
// some amount of time.
//
// This is only useful when dial attempts happen from a pre-determined port,
// for example when you are dialing from the same connection you are listening on
// to punch through NAT, and helps with the fact that KCP is state-less.
// This helps better deal with scenarios where a process on one of the side (A)
// get's restarted, and stray packets from other side (B) makes it look like
// as if someone is trying to connect to A. Even if session dies on B,
// new stray reply packets from A resurrect the session on B, causing the
// session to be alive forever.
BlacklistDuration time.Duration
blacklist = blacklistMap{
entries: make(map[sessionKey]time.Time),
}
)
// a global map for blacklisting conversations
type blacklistMap struct {
entries map[sessionKey]time.Time
reapAt time.Time
mut sync.Mutex
}
func (m *blacklistMap) add(address string, conv uint32) {
if BlacklistDuration == 0 {
return
}
m.mut.Lock()
timeout := time.Now().Add(BlacklistDuration)
m.entries[sessionKey{
addr: address,
convID: conv,
}] = timeout
m.reap()
m.mut.Unlock()
}
func (m *blacklistMap) has(address string, conv uint32) bool {
if BlacklistDuration == 0 {
return false
}
m.mut.Lock()
t, ok := m.entries[sessionKey{
addr: address,
convID: conv,
}]
m.mut.Unlock()
return ok && t.After(time.Now())
}
func (m *blacklistMap) reap() {
now := time.Now()
for k, t := range m.entries {
if t.Before(now) {
delete(m.entries, k)
}
}
}