safing-portmaster/network/state/udp.go
2020-05-20 14:53:03 +02:00

125 lines
3.3 KiB
Go

package state
import (
"context"
"time"
"github.com/safing/portmaster/network/packet"
"github.com/safing/portmaster/network/socket"
)
type udpState struct {
inbound bool
lastSeen time.Time
}
const (
// UDPConnStateTTL is the maximum time a udp connection state is held.
UDPConnStateTTL = 72 * time.Hour
// UDPConnStateShortenedTTL is a shortened maximum time a udp connection state is held, if there more entries than defined by AggressiveCleaningThreshold.
UDPConnStateShortenedTTL = 3 * time.Hour
// AggressiveCleaningThreshold defines the soft limit of udp connection state held per udp socket.
AggressiveCleaningThreshold = 256
)
var (
udp4States = make(map[string]map[string]*udpState) // locked with udp4Lock
udp6States = make(map[string]map[string]*udpState) // locked with udp6Lock
)
func getUDPConnState(socketInfo *socket.BindInfo, udpStates map[string]map[string]*udpState, remoteAddress socket.Address) (udpConnState *udpState, ok bool) {
bindMap, ok := udpStates[makeUDPStateKey(socketInfo.Local)]
if ok {
udpConnState, ok = bindMap[makeUDPStateKey(remoteAddress)]
return
}
return nil, false
}
func getUDPDirection(socketInfo *socket.BindInfo, udpStates map[string]map[string]*udpState, pktInfo *packet.Info) (connDirection bool) {
localKey := makeUDPStateKey(socketInfo.Local)
bindMap, ok := udpStates[localKey]
if !ok {
bindMap = make(map[string]*udpState)
udpStates[localKey] = bindMap
}
remoteKey := makeUDPStateKey(socket.Address{
IP: pktInfo.RemoteIP(),
Port: pktInfo.RemotePort(),
})
udpConnState, ok := bindMap[remoteKey]
if !ok {
bindMap[remoteKey] = &udpState{
inbound: pktInfo.Inbound,
lastSeen: time.Now().UTC(),
}
return pktInfo.Inbound
}
udpConnState.lastSeen = time.Now().UTC()
return udpConnState.inbound
}
// CleanUDPStates cleans the udp connection states which save connection directions.
func CleanUDPStates(_ context.Context) {
now := time.Now().UTC()
udp4Lock.Lock()
updateUDP4Table()
cleanStates(udp4Binds, udp4States, now)
udp4Lock.Unlock()
udp6Lock.Lock()
updateUDP6Table()
cleanStates(udp6Binds, udp6States, now)
udp6Lock.Unlock()
}
func cleanStates(
binds []*socket.BindInfo,
udpStates map[string]map[string]*udpState,
now time.Time,
) {
// compute thresholds
threshold := now.Add(-UDPConnStateTTL)
shortThreshhold := now.Add(-UDPConnStateShortenedTTL)
// make lookup map of all active keys
bindKeys := make(map[string]struct{})
for _, socketInfo := range binds {
bindKeys[makeUDPStateKey(socketInfo.Local)] = struct{}{}
}
// clean the udp state storage
for localKey, bindMap := range udpStates {
if _, active := bindKeys[localKey]; active {
// clean old entries
for remoteKey, udpConnState := range bindMap {
if udpConnState.lastSeen.Before(threshold) {
delete(bindMap, remoteKey)
}
}
// if there are too many clean more aggressively
if len(bindMap) > AggressiveCleaningThreshold {
for remoteKey, udpConnState := range bindMap {
if udpConnState.lastSeen.Before(shortThreshhold) {
delete(bindMap, remoteKey)
}
}
}
} else {
// delete the whole thing
delete(udpStates, localKey)
}
}
}
func makeUDPStateKey(address socket.Address) string {
// This could potentially go wrong, but as all IPs are created by the same source, everything should be fine.
return string(address.IP) + string(address.Port)
}