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retry domain lookups

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This commit is contained in:
Fran Bull 2025-04-30 14:52:39 -07:00
parent e548a515ca
commit 2a132cf5bd
1 changed files with 32 additions and 9 deletions
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41
cmd/natc/ippool/consensusippool.go
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@ -42,16 +42,8 @@ type ConsensusIPPool struct {
// DomainForIP is part of the IPPool interface. It returns a domain for a given IP address, if we have
// previously assigned the IP address to a domain for the node that is asking. Otherwise it logs and returns the empty string.
func (ipp *ConsensusIPPool) DomainForIP(from tailcfg.NodeID, addr netip.Addr, updatedAt time.Time) (string, bool) {
pm, ok := ipp.perPeerMap.Load(from)
ww, ok := ipp.retryDomainLookup(from, addr, 0)
if !ok {
log.Printf("DomainForIP: peer state absent for: %d", from)
return "", false
}
pm.mu.Lock()
defer pm.mu.Unlock()
ww, ok := pm.addrToDomain.Lookup(addr)
if !ok {
log.Printf("DomainForIP: peer state doesn't recognize addr: %s", addr)
return "", false
}
go func() {
@ -63,6 +55,37 @@ func (ipp *ConsensusIPPool) DomainForIP(from tailcfg.NodeID, addr netip.Addr, up
return ww.Domain, true
}
// retryDomainLookup tries to lookup the domain for this IP+node. If it can't find the node or the IP it
// tries again up to 5 times, with exponential backoff.
// The raft lib will tell the leader that a log entry has been applied to a quorum of nodes, sometimes before the
// log entry has been applied to the local state. This means that in our case the traffic on an IP can arrive before
// we have the domain for which that IP applies stored.
func (ipp *ConsensusIPPool) retryDomainLookup(from tailcfg.NodeID, addr netip.Addr, n int) (whereWhen, bool) {
ps, foundPeerState := ipp.perPeerMap.Load(from)
if foundPeerState {
ps.mu.Lock()
ww, foundDomain := ps.addrToDomain.Lookup(addr)
ps.mu.Unlock()
if foundDomain {
return ww, true
}
}
if n > 4 {
if !foundPeerState {
log.Printf("DomainForIP: peer state absent for: %d", from)
} else {
log.Printf("DomainForIP: peer state doesn't recognize addr: %s", addr)
}
return whereWhen{}, false
}
timeToWait := 100
for i := 0; i < n; i++ {
timeToWait *= 2
}
time.Sleep(time.Millisecond * time.Duration(timeToWait))
return ipp.retryDomainLookup(from, addr, n+1)
}
type markLastUsedArgs struct {
NodeID tailcfg.NodeID
Addr netip.Addr