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6 Commits

Author SHA1 Message Date
Zoltán Papp
3cdfa11cb8 client/dns/mgmt: strip wildcard prefix in pool-root membership check
isUnderPoolRoot lowercased and trimmed the trailing dot, but did not
strip a leading "*." wildcard the way server.toZone does via
nbdns.NormalizeZone. If a mgmt-advertised Relay URL ever comes through
as "*.relay.netbird.io", the handler-chain registration side strips
the wildcard (toZone) but the membership check here would keep it,
so HasSuffix(".*.relay.netbird.io") would never match legitimate
instance subdomains and on-demand resolves would not fire.

Today the extractor lowercases + IDNA-normalizes URLs and rejects the
wildcard form, so the divergence is latent. Close it anyway by running
both sides of the membership check through a shared
canonicalizePoolDomain helper that mirrors toZone's transformation
(modulo trailing-dot orientation, which is self-consistent within
this function). toZone itself lives in the parent dns package and
cannot be imported here without a cycle.
2026-04-24 22:48:25 +02:00
Zoltán Papp
12d0edabc0 client/dns: split UpdateServerConfig helpers to cut cognitive complexity
UpdateServerConfig was at 31; SonarCloud threshold is 20. The deep
nesting came from wrapping the whole body in the mgmtCacheResolver
nil-check and stacking five for-loops + conditionals inside it.

Invert to an early return when the resolver is nil, then split the
remaining work into two focused helpers:

- registerMgmtCacheHandlers: handler-chain wiring (pool-root
  subdomain wrapper + exact-match registration) with the toZone-
  canonicalized membership check.
- reconcileMgmtPoolRoots: extraDomains refcounting against the
  current pool-root set, plus the mgmtPoolRoots tracking map.

Pure refactor — behaviour is identical.
2026-04-24 22:38:49 +02:00
Zoltán Papp
b0b52b6774 client/dns/mgmt: singleflight on-demand resolves
resolveOnDemand deduplicated the cache write but not the upstream
lookup — a burst of concurrent queries for a freshly-learned pool-root
subdomain (A + AAAA from a single getaddrinfo, or multiple peer
workers dialing the same foreign relay) each hit the bypass resolver
independently.

Wrap the lookupRecords call in refreshGroup.Do with an 'ondemand:'-
prefixed key so concurrent callers collapse into one request; the
prefix namespaces this key off scheduleRefresh's keyspace so the two
paths don't collide.

Error and empty-result paths preserved; the cache write still runs
under the existing TOCTOU-safe exists check + mutex so a winning
refresh isn't clobbered.
2026-04-24 22:36:18 +02:00
Zoltán Papp
c89c30bb28 client/dns: canonicalize pool-root membership check with toZone
GetPoolRootDomains returns what the extractor stored; GetCachedDomains
strips the trailing dot from question names. Today those happen to
produce the same domain.Domain string because both sources run through
domain.FromString, but relying on that parity is fragile.

Run both sides of the poolRootSet membership check through toZone so
the comparison is independent of each source's canonical form.
Prevents a future extractor or cache-entry path from silently routing
a pool-root into exactDomains, where a second registerHandler call
with the bare resolver would clobber the subdomainMatchHandler
registration (AddHandler replaces entries with the same pattern +
priority).
2026-04-24 22:33:41 +02:00
Zoltán Papp
14be474e3d client/dns: register pool-root domains as host-manager match domains
The subdomain-matching handler chain entry only helps when the OS DNS
manager routes the query to the daemon's listener. On systems using
systemd-resolved (Ubuntu 20.04 / 22.04, most modern Debian/RHEL-family
distros), the daemon delegates a *specific set* of match domains to
the wt0 link via D-Bus. Any FQDN outside that set is answered from
the host's global upstream DNS, never touching the handler chain.

With only 'netbird.cloud' and the in-addr.arpa reverse zone advertised
as match domains, a relay instance FQDN like
streamline-de-fra1-0.relay.netbird.io is resolved globally. When an
exit-node default route is active on wt0 but the peer is not yet
live, that global lookup times out on the local stub (127.0.0.53)
because systemd-resolved's uplink DNS is unreachable through the
overlay, and the foreign-relay dial fails exactly the way the
ENOKEY path did on file-manager hosts.

Bump the pool-root domains (ServerDomains.Relay entries) into
extraDomains so applyHostConfig adds them as match-only domains
alongside 'netbird.cloud'. systemd-resolved then delegates
*.relay.netbird.io to the wt0 link, queries hit the daemon's DNS
listener, and the on-demand resolve path via the bypass resolver
runs as intended.

Tracking map mgmtPoolRoots isolates this refcount from the
RegisterHandler path so updates across successive mgmt syncs
increment/decrement only the changed set.
2026-04-24 18:01:26 +02:00
Zoltán Papp
77ec25796e client/dns/mgmt: bypass overlay for control-plane FQDN resolution
When an exit-node peer's network-map installs a 0.0.0.0/0 default route
on the overlay interface before that peer's WireGuard key material is
active, any UDP socket dialing an off-link address is routed into wt0
and the kernel returns ENOKEY.

Two places needed fixing:

 1. The mgmt cache refresh path. It reactively refreshes the
    control-plane FQDNs advertised by the mgmt (api/signal/stun/turn/
    the Relay pool root) after the daemon has installed its own
    resolv.conf pointing at the overlay listener. Previously the
    refresh dial followed the chain's upstream handler, which followed
    the overlay default route and deadlocked on ENOKEY.

 2. Foreign relay FQDN resolution. When a remote peer is homed on a
    different relay instance than us, we need to resolve a streamline-*
    subdomain that is not in the cache. That lookup went through the
    same overlay-routed upstream and failed identically, deadlocking
    the exit-node test whenever the relay LB put the two peers on
    different instances.

Fix both by giving the mgmt cache a dedicated net.Resolver that dials
the original pre-NetBird system nameservers through nbnet.NewDialer.
The dialer marks the socket as control-plane (SO_MARK on Linux,
IP_BOUND_IF on darwin, IP_UNICAST_IF on Windows); the routemanager's
policy rules keep those sockets on the underlay regardless of the
overlay default.

Pool-root domains (the Relay entries in ServerDomains) now register
through a subdomain-matching wrapper so that instance subdomains like
streamline-de-fra1-0.relay.netbird.io also hit the mgmt cache handler.
On cache miss under a pool root, ServeDNS resolves the FQDN on demand
through the bypass resolver, caches the result, and returns it.

Pool-root membership is derived dynamically from mgmt-advertised
ServerDomains.Relay[] — no hardcoded domain lists, no protocol change.
No hardcoded fallback nameservers: if the host had no original system
resolver at all, the bypass resolver stays nil and the stale-while-
revalidate cache keeps serving. The general upstream forwarder and
the user DNS path are unchanged.
2026-04-24 17:40:33 +02:00
3 changed files with 375 additions and 25 deletions

View File

@@ -0,0 +1,55 @@
package mgmt
import (
"context"
"fmt"
"net"
"net/netip"
nbnet "github.com/netbirdio/netbird/client/net"
)
// NewBypassResolver builds a *net.Resolver that sends queries directly to
// the supplied nameservers through a socket that bypasses the NetBird
// overlay interface. This lets the mgmt cache refresh control-plane
// FQDNs (api/signal/relay/stun/turn) even when an exit-node default
// route is installed on the overlay before its peer is live.
//
// Returns nil if nameservers is empty. The caller must not pass
// loopback/overlay IPs (e.g. 127.0.0.1, the overlay listener address);
// those would defeat the purpose of bypassing.
func NewBypassResolver(nameservers []netip.Addr) *net.Resolver {
if len(nameservers) == 0 {
return nil
}
servers := make([]string, 0, len(nameservers))
for _, ns := range nameservers {
if !ns.IsValid() || ns.IsLoopback() || ns.IsUnspecified() {
continue
}
servers = append(servers, netip.AddrPortFrom(ns, 53).String())
}
if len(servers) == 0 {
return nil
}
return &net.Resolver{
PreferGo: true,
Dial: func(ctx context.Context, network, _ string) (net.Conn, error) {
nbDialer := nbnet.NewDialer()
var lastErr error
for _, ns := range servers {
conn, err := nbDialer.DialContext(ctx, network, ns)
if err == nil {
return conn, nil
}
lastErr = err
}
if lastErr == nil {
return nil, fmt.Errorf("no bypass nameservers configured")
}
return nil, fmt.Errorf("dial bypass nameservers: %w", lastErr)
},
}
}

View File

@@ -8,6 +8,7 @@ import (
"net/url" "net/url"
"os" "os"
"slices" "slices"
"strconv"
"strings" "strings"
"sync" "sync"
"sync/atomic" "sync/atomic"
@@ -71,6 +72,14 @@ type Resolver struct {
refreshing map[dns.Question]*atomic.Bool refreshing map[dns.Question]*atomic.Bool
cacheTTL time.Duration cacheTTL time.Duration
// bypassResolver, when non-nil, is used by osLookup instead of
// net.DefaultResolver. It is constructed by the caller to dial the
// original (pre-NetBird) system nameservers through a socket that
// bypasses the overlay interface (control-plane fwmark / bound iface),
// so that when an exit-node default route is installed before a peer
// is handshaked the refresh does not fail with ENOKEY.
bypassResolver *net.Resolver
} }
// NewResolver creates a new management domains cache resolver. // NewResolver creates a new management domains cache resolver.
@@ -98,8 +107,28 @@ func (m *Resolver) SetChainResolver(chain ChainResolver, maxPriority int) {
m.mutex.Unlock() m.mutex.Unlock()
} }
// SetBypassResolver installs a resolver that osLookup uses instead of
// net.DefaultResolver. It is intended to dial the original (pre-NetBird)
// system nameservers through a socket that does not follow the overlay
// default route, so that a refresh initiated while an exit node is active
// but its WireGuard peer is not yet installed cannot deadlock on ENOKEY.
// Passing nil restores use of net.DefaultResolver.
func (m *Resolver) SetBypassResolver(r *net.Resolver) {
m.mutex.Lock()
m.bypassResolver = r
m.mutex.Unlock()
}
// ServeDNS serves cached A/AAAA records. Stale entries are returned // ServeDNS serves cached A/AAAA records. Stale entries are returned
// immediately and refreshed asynchronously (stale-while-revalidate). // immediately and refreshed asynchronously (stale-while-revalidate).
//
// If the query name is not in the cache but falls under a pool-root
// domain (a domain the mgmt advertised in ServerDomains.Relay, whose
// instance subdomains like streamline-de-fra1-0.relay.netbird.io are
// part of the relay pool), resolve it on demand through the bypass
// resolver and cache the result. This is what lets the daemon reach
// a foreign relay FQDN after an exit-node default route has been
// installed on the overlay before its peer is live.
func (m *Resolver) ServeDNS(w dns.ResponseWriter, r *dns.Msg) { func (m *Resolver) ServeDNS(w dns.ResponseWriter, r *dns.Msg) {
if len(r.Question) == 0 { if len(r.Question) == 0 {
m.continueToNext(w, r) m.continueToNext(w, r)
@@ -126,6 +155,10 @@ func (m *Resolver) ServeDNS(w dns.ResponseWriter, r *dns.Msg) {
m.mutex.RUnlock() m.mutex.RUnlock()
if !found { if !found {
if m.isUnderPoolRoot(question.Name) {
m.resolveOnDemand(w, r, question)
return
}
m.continueToNext(w, r) m.continueToNext(w, r)
return return
} }
@@ -155,12 +188,117 @@ func (m *Resolver) ServeDNS(w dns.ResponseWriter, r *dns.Msg) {
} }
} }
// MatchSubdomains returns false since this resolver only handles exact domain matches // MatchSubdomains returns false by default: the bare resolver is registered
// for NetBird infrastructure domains (signal, relay, flow, etc.), not their subdomains. // against exact domains. Pool-root domains (currently Relay entries from
// ServerDomains) are registered through a subdomain-matching wrapper at
// the call site instead, so instance subdomains hit this handler and get
// the on-demand resolve path in ServeDNS.
func (m *Resolver) MatchSubdomains() bool { func (m *Resolver) MatchSubdomains() bool {
return false return false
} }
// isUnderPoolRoot reports whether fqdn is an instance subdomain under any
// pool-root domain advertised by the mgmt (currently ServerDomains.Relay),
// e.g. "streamline-de-fra1-0.relay.netbird.io." is under "relay.netbird.io".
// The pool-root itself is not considered a subdomain (it matches the exact
// cache entry populated by AddDomain instead).
//
// Canonicalization mirrors server.toZone — lowercase, strip trailing dot,
// and strip a leading "*." wildcard (via canonicalizePoolDomain) — so the
// membership check is consistent with the handler-chain registration that
// runs the same set through toZone. toZone itself lives in the parent dns
// package and cannot be imported from here without a cycle.
func (m *Resolver) isUnderPoolRoot(fqdn string) bool {
m.mutex.RLock()
defer m.mutex.RUnlock()
if m.serverDomains == nil {
return false
}
fqdn = canonicalizePoolDomain(fqdn)
if fqdn == "" {
return false
}
for _, root := range m.serverDomains.Relay {
r := canonicalizePoolDomain(root.PunycodeString())
if r == "" || fqdn == r {
continue
}
if strings.HasSuffix(fqdn, "."+r) {
return true
}
}
return false
}
// canonicalizePoolDomain normalizes a domain for pool-root membership
// comparison: lowercase, trailing dot stripped, leading "*." wildcard
// stripped. Matches the transformation server.toZone applies on the
// handler-registration side (modulo trailing-dot orientation, which is
// self-consistent within this file).
func canonicalizePoolDomain(s string) string {
s = strings.ToLower(strings.TrimSuffix(s, "."))
s = strings.TrimPrefix(s, "*.")
return s
}
// resolveOnDemand resolves an uncached pool-root subdomain (e.g. a relay
// instance FQDN) through the bypass resolver path, caches the result, and
// writes it back to w. Falls through to the next handler on error so the
// normal chain can still attempt the resolve.
func (m *Resolver) resolveOnDemand(w dns.ResponseWriter, r *dns.Msg, question dns.Question) {
d, err := domain.FromString(strings.TrimSuffix(question.Name, "."))
if err != nil {
log.Debugf("on-demand resolve: parse domain %q: %v", question.Name, err)
m.continueToNext(w, r)
return
}
// Collapse concurrent on-demand lookups for the same (name, qtype) into
// a single upstream query via singleflight. A burst of parallel queries
// for a freshly-learned pool-root subdomain (e.g. multiple peer workers
// dialing the same foreign relay, or A + AAAA racing each other) would
// otherwise each hit the bypass resolver independently. The prefix
// namespaces this key off scheduleRefresh's keyspace so the two paths
// can coexist without collisions.
key := "ondemand:" + question.Name + ":" + strconv.Itoa(int(question.Qtype))
result, err, _ := m.refreshGroup.Do(key, func() (any, error) {
ctx, cancel := context.WithTimeout(context.Background(), dnsTimeout)
defer cancel()
return m.lookupRecords(ctx, d, question)
})
if err != nil {
log.Debugf("on-demand resolve %s type=%s: %v",
d.SafeString(), dns.TypeToString[question.Qtype], err)
m.continueToNext(w, r)
return
}
records, _ := result.([]dns.RR)
if len(records) == 0 {
m.continueToNext(w, r)
return
}
now := time.Now()
m.mutex.Lock()
if _, exists := m.records[question]; !exists {
m.records[question] = &cachedRecord{records: records, cachedAt: now}
}
m.mutex.Unlock()
resp := &dns.Msg{}
resp.SetReply(r)
resp.Authoritative = false
resp.RecursionAvailable = true
resp.Answer = cloneRecordsWithTTL(records, uint32(m.cacheTTL.Seconds()))
log.Debugf("on-demand resolved %d records for domain=%s", len(resp.Answer), question.Name)
if err := w.WriteMsg(resp); err != nil {
log.Errorf("failed to write on-demand response: %v", err)
}
}
// continueToNext signals the handler chain to continue to the next handler. // continueToNext signals the handler chain to continue to the next handler.
func (m *Resolver) continueToNext(w dns.ResponseWriter, r *dns.Msg) { func (m *Resolver) continueToNext(w dns.ResponseWriter, r *dns.Msg) {
resp := &dns.Msg{} resp := &dns.Msg{}
@@ -315,14 +453,29 @@ func (m *Resolver) markRefreshFailed(question dns.Question, expected *cachedReco
return c.consecFailures return c.consecFailures
} }
// lookupBoth resolves A and AAAA via chain or OS. Per-family errors let // lookupBoth resolves A and AAAA via bypass resolver, chain, or OS.
// callers tell records, NODATA (nil err, no records), and failure apart. // Per-family errors let callers tell records, NODATA (nil err, no records),
// and failure apart.
//
// Preference order:
// 1. bypassResolver (direct, overlay-bypassing dial to original system
// nameservers; immune to the exit-node ENOKEY race).
// 2. chain (handler chain; used when NetBird is the system resolver and
// no bypass resolver is installed).
// 3. net.DefaultResolver via osLookup (legacy fallback).
func (m *Resolver) lookupBoth(ctx context.Context, d domain.Domain, dnsName string) (aRecords, aaaaRecords []dns.RR, errA, errAAAA error) { func (m *Resolver) lookupBoth(ctx context.Context, d domain.Domain, dnsName string) (aRecords, aaaaRecords []dns.RR, errA, errAAAA error) {
m.mutex.RLock() m.mutex.RLock()
chain := m.chain chain := m.chain
maxPriority := m.chainMaxPriority maxPriority := m.chainMaxPriority
bypass := m.bypassResolver
m.mutex.RUnlock() m.mutex.RUnlock()
if bypass != nil {
aRecords, errA = m.osLookup(ctx, d, dnsName, dns.TypeA)
aaaaRecords, errAAAA = m.osLookup(ctx, d, dnsName, dns.TypeAAAA)
return
}
if chain != nil && chain.HasRootHandlerAtOrBelow(maxPriority) { if chain != nil && chain.HasRootHandlerAtOrBelow(maxPriority) {
aRecords, errA = m.lookupViaChain(ctx, chain, maxPriority, dnsName, dns.TypeA) aRecords, errA = m.lookupViaChain(ctx, chain, maxPriority, dnsName, dns.TypeA)
aaaaRecords, errAAAA = m.lookupViaChain(ctx, chain, maxPriority, dnsName, dns.TypeAAAA) aaaaRecords, errAAAA = m.lookupViaChain(ctx, chain, maxPriority, dnsName, dns.TypeAAAA)
@@ -337,15 +490,22 @@ func (m *Resolver) lookupBoth(ctx context.Context, d domain.Domain, dnsName stri
return return
} }
// lookupRecords resolves a single record type via chain or OS. The OS branch // lookupRecords resolves a single record type. See lookupBoth for the
// arms the loop detector for the duration of its call so that ServeDNS can // preference order. The OS branch arms the loop detector for the duration
// spot the OS resolver routing the recursive query back to us. // of its call so that ServeDNS can spot the OS resolver routing the
// recursive query back to us; the bypass branch skips the loop detector
// because its dial does not enter the system resolver.
func (m *Resolver) lookupRecords(ctx context.Context, d domain.Domain, q dns.Question) ([]dns.RR, error) { func (m *Resolver) lookupRecords(ctx context.Context, d domain.Domain, q dns.Question) ([]dns.RR, error) {
m.mutex.RLock() m.mutex.RLock()
chain := m.chain chain := m.chain
maxPriority := m.chainMaxPriority maxPriority := m.chainMaxPriority
bypass := m.bypassResolver
m.mutex.RUnlock() m.mutex.RUnlock()
if bypass != nil {
return m.osLookup(ctx, d, q.Name, q.Qtype)
}
if chain != nil && chain.HasRootHandlerAtOrBelow(maxPriority) { if chain != nil && chain.HasRootHandlerAtOrBelow(maxPriority) {
return m.lookupViaChain(ctx, chain, maxPriority, q.Name, q.Qtype) return m.lookupViaChain(ctx, chain, maxPriority, q.Name, q.Qtype)
} }
@@ -394,9 +554,9 @@ func (m *Resolver) lookupViaChain(ctx context.Context, chain ChainResolver, maxP
return filtered, nil return filtered, nil
} }
// osLookup resolves a single family via net.DefaultResolver using resutil, // osLookup resolves a single family via the bypass resolver (if configured)
// which disambiguates NODATA from NXDOMAIN and Unmaps v4-mapped-v6. NODATA // or net.DefaultResolver using resutil, which disambiguates NODATA from
// returns (nil, nil). // NXDOMAIN and Unmaps v4-mapped-v6. NODATA returns (nil, nil).
func (m *Resolver) osLookup(ctx context.Context, d domain.Domain, dnsName string, qtype uint16) ([]dns.RR, error) { func (m *Resolver) osLookup(ctx context.Context, d domain.Domain, dnsName string, qtype uint16) ([]dns.RR, error) {
network := resutil.NetworkForQtype(qtype) network := resutil.NetworkForQtype(qtype)
if network == "" { if network == "" {
@@ -406,7 +566,14 @@ func (m *Resolver) osLookup(ctx context.Context, d domain.Domain, dnsName string
log.Infof("looking up IP for mgmt domain=%s type=%s", d.SafeString(), dns.TypeToString[qtype]) log.Infof("looking up IP for mgmt domain=%s type=%s", d.SafeString(), dns.TypeToString[qtype])
defer log.Infof("done looking up IP for mgmt domain=%s type=%s", d.SafeString(), dns.TypeToString[qtype]) defer log.Infof("done looking up IP for mgmt domain=%s type=%s", d.SafeString(), dns.TypeToString[qtype])
result := resutil.LookupIP(ctx, net.DefaultResolver, network, d.PunycodeString(), qtype) m.mutex.RLock()
resolver := m.bypassResolver
m.mutex.RUnlock()
if resolver == nil {
resolver = net.DefaultResolver
}
result := resutil.LookupIP(ctx, resolver, network, d.PunycodeString(), qtype)
if result.Rcode == dns.RcodeSuccess { if result.Rcode == dns.RcodeSuccess {
return resutil.IPsToRRs(dnsName, result.IPs, uint32(m.cacheTTL.Seconds())), nil return resutil.IPsToRRs(dnsName, result.IPs, uint32(m.cacheTTL.Seconds())), nil
} }
@@ -467,6 +634,24 @@ func (m *Resolver) RemoveDomain(d domain.Domain) error {
return nil return nil
} }
// GetPoolRootDomains returns the set of domains that should be registered
// with subdomain matching (currently the Relay entries from ServerDomains).
// Instance subdomains under these roots are resolved on demand in ServeDNS.
func (m *Resolver) GetPoolRootDomains() domain.List {
m.mutex.RLock()
defer m.mutex.RUnlock()
if m.serverDomains == nil {
return nil
}
out := make(domain.List, 0, len(m.serverDomains.Relay))
for _, d := range m.serverDomains.Relay {
if d != "" {
out = append(out, d)
}
}
return out
}
// GetCachedDomains returns a list of all cached domains. // GetCachedDomains returns a list of all cached domains.
func (m *Resolver) GetCachedDomains() domain.List { func (m *Resolver) GetCachedDomains() domain.List {
m.mutex.RLock() m.mutex.RLock()

View File

@@ -31,6 +31,28 @@ import (
const envSkipDNSProbe = "NB_SKIP_DNS_PROBE" const envSkipDNSProbe = "NB_SKIP_DNS_PROBE"
// subdomainMatchHandler is a thin wrapper used to register a handler under
// a pool-root domain (e.g. a relay URL advertised by the mgmt) with
// subdomain matching enabled. The underlying handler's own MatchSubdomains
// is left untouched so that exact-match registrations keep their
// semantics.
type subdomainMatchHandler struct {
dns.Handler
}
// MatchSubdomains lets the handler chain route any instance subdomain
// (e.g. streamline-de-fra1-0.relay.netbird.io) to the wrapped handler.
func (subdomainMatchHandler) MatchSubdomains() bool { return true }
// String returns a debug-friendly name; the chain uses fmt.Stringer for
// its "registering handler X" logs.
func (h subdomainMatchHandler) String() string {
if s, ok := h.Handler.(fmt.Stringer); ok {
return s.String() + "[subdomains]"
}
return "subdomainMatchHandler"
}
// ReadyListener is a notification mechanism what indicate the server is ready to handle host dns address changes // ReadyListener is a notification mechanism what indicate the server is ready to handle host dns address changes
type ReadyListener interface { type ReadyListener interface {
OnReady() OnReady()
@@ -95,6 +117,11 @@ type DefaultServer struct {
batchMode bool batchMode bool
mgmtCacheResolver *mgmt.Resolver mgmtCacheResolver *mgmt.Resolver
// mgmtPoolRoots tracks pool-root domains currently contributed to
// extraDomains by the mgmt cache, so the next UpdateServerConfig can
// decrement the old set before incrementing the new one without
// disturbing unrelated registerHandler callers.
mgmtPoolRoots map[domain.Domain]struct{}
// permanent related properties // permanent related properties
permanent bool permanent bool
@@ -229,6 +256,7 @@ func newDefaultServer(
hostsDNSHolder: newHostsDNSHolder(), hostsDNSHolder: newHostsDNSHolder(),
hostManager: &noopHostConfigurator{}, hostManager: &noopHostConfigurator{},
mgmtCacheResolver: mgmtCacheResolver, mgmtCacheResolver: mgmtCacheResolver,
mgmtPoolRoots: make(map[domain.Domain]struct{}),
currentConfigHash: ^uint64(0), // Initialize to max uint64 to ensure first config is always applied currentConfigHash: ^uint64(0), // Initialize to max uint64 to ensure first config is always applied
} }
@@ -587,25 +615,92 @@ func (s *DefaultServer) UpdateServerConfig(domains dnsconfig.ServerDomains) erro
s.mux.Lock() s.mux.Lock()
defer s.mux.Unlock() defer s.mux.Unlock()
if s.mgmtCacheResolver != nil { if s.mgmtCacheResolver == nil {
removedDomains, err := s.mgmtCacheResolver.UpdateFromServerDomains(s.ctx, domains) return nil
if err != nil {
return fmt.Errorf("update management cache resolver: %w", err)
}
if len(removedDomains) > 0 {
s.deregisterHandler(removedDomains.ToPunycodeList(), PriorityMgmtCache)
}
newDomains := s.mgmtCacheResolver.GetCachedDomains()
if len(newDomains) > 0 {
s.registerHandler(newDomains.ToPunycodeList(), s.mgmtCacheResolver, PriorityMgmtCache)
}
} }
removedDomains, err := s.mgmtCacheResolver.UpdateFromServerDomains(s.ctx, domains)
if err != nil {
return fmt.Errorf("update management cache resolver: %w", err)
}
if len(removedDomains) > 0 {
s.deregisterHandler(removedDomains.ToPunycodeList(), PriorityMgmtCache)
}
poolRoots := s.mgmtCacheResolver.GetPoolRootDomains()
s.registerMgmtCacheHandlers(poolRoots)
s.reconcileMgmtPoolRoots(poolRoots)
if !s.batchMode {
s.applyHostConfig()
}
return nil return nil
} }
// registerMgmtCacheHandlers wires the mgmt cache resolver into the handler
// chain for the current set of cached domains. Pool-root domains (advertised
// by the mgmt as Relay URLs) go through a thin subdomain-matching wrapper so
// a query like "streamline-de-fra1-0.relay.netbird.io" routes to the mgmt
// cache resolver, which resolves it on demand through the bypass resolver
// instead of falling through to the overlay-routed upstream handler.
//
// Canonicalize with toZone on both sides of the pool-root membership check so
// the comparison is independent of each source's canonical form:
// GetPoolRootDomains returns what the extractor stored; GetCachedDomains
// strips the trailing dot from question names.
func (s *DefaultServer) registerMgmtCacheHandlers(poolRoots domain.List) {
poolRootSet := make(map[domain.Domain]struct{}, len(poolRoots))
for _, d := range poolRoots {
poolRootSet[toZone(d)] = struct{}{}
}
if len(poolRoots) > 0 {
s.registerHandler(poolRoots.ToPunycodeList(), subdomainMatchHandler{Handler: s.mgmtCacheResolver}, PriorityMgmtCache)
}
var exactDomains domain.List
for _, d := range s.mgmtCacheResolver.GetCachedDomains() {
if _, isPool := poolRootSet[toZone(d)]; isPool {
continue
}
exactDomains = append(exactDomains, d)
}
if len(exactDomains) > 0 {
s.registerHandler(exactDomains.ToPunycodeList(), s.mgmtCacheResolver, PriorityMgmtCache)
}
}
// reconcileMgmtPoolRoots keeps extraDomains in sync with the current mgmt
// pool-root set. These entries show up as *match* domains for the host DNS
// manager (systemd-resolved, NetworkManager, etc.) so instance subdomain
// queries like streamline-* are delegated to the wt0 link where the daemon's
// DNS listener sits. Without this, systemd-resolved answers them from the
// host's global upstream, skipping our handler chain entirely.
//
// Uses s.mgmtPoolRoots as a dedicated tracking map so increments/decrements
// here don't collide with RegisterHandler's refcounting.
func (s *DefaultServer) reconcileMgmtPoolRoots(poolRoots domain.List) {
newPoolRoots := make(map[domain.Domain]struct{}, len(poolRoots))
for _, d := range poolRoots {
zone := toZone(d)
newPoolRoots[zone] = struct{}{}
if _, already := s.mgmtPoolRoots[zone]; !already {
s.extraDomains[zone]++
}
}
for zone := range s.mgmtPoolRoots {
if _, keep := newPoolRoots[zone]; keep {
continue
}
s.extraDomains[zone]--
if s.extraDomains[zone] <= 0 {
delete(s.extraDomains, zone)
}
}
s.mgmtPoolRoots = newPoolRoots
}
func (s *DefaultServer) applyConfiguration(update nbdns.Config) error { func (s *DefaultServer) applyConfiguration(update nbdns.Config) error {
// is the service should be Disabled, we stop the listener or fake resolver // is the service should be Disabled, we stop the listener or fake resolver
if update.ServiceEnable { if update.ServiceEnable {
@@ -759,6 +854,9 @@ func (s *DefaultServer) registerFallback(config HostDNSConfig) {
originalNameservers := hostMgrWithNS.getOriginalNameservers() originalNameservers := hostMgrWithNS.getOriginalNameservers()
if len(originalNameservers) == 0 { if len(originalNameservers) == 0 {
s.deregisterHandler([]string{nbdns.RootZone}, PriorityFallback) s.deregisterHandler([]string{nbdns.RootZone}, PriorityFallback)
if s.mgmtCacheResolver != nil {
s.mgmtCacheResolver.SetBypassResolver(nil)
}
return return
} }
@@ -777,6 +875,7 @@ func (s *DefaultServer) registerFallback(config HostDNSConfig) {
} }
handler.routeMatch = s.routeMatch handler.routeMatch = s.routeMatch
var bypassNameservers []netip.Addr
for _, ns := range originalNameservers { for _, ns := range originalNameservers {
if ns == config.ServerIP { if ns == config.ServerIP {
log.Debugf("skipping original nameserver %s as it is the same as the server IP %s", ns, config.ServerIP) log.Debugf("skipping original nameserver %s as it is the same as the server IP %s", ns, config.ServerIP)
@@ -785,11 +884,22 @@ func (s *DefaultServer) registerFallback(config HostDNSConfig) {
addrPort := netip.AddrPortFrom(ns, DefaultPort) addrPort := netip.AddrPortFrom(ns, DefaultPort)
handler.upstreamServers = append(handler.upstreamServers, addrPort) handler.upstreamServers = append(handler.upstreamServers, addrPort)
bypassNameservers = append(bypassNameservers, ns)
} }
handler.deactivate = func(error) { /* always active */ } handler.deactivate = func(error) { /* always active */ }
handler.reactivate = func() { /* always active */ } handler.reactivate = func() { /* always active */ }
s.registerHandler([]string{nbdns.RootZone}, handler, PriorityFallback) s.registerHandler([]string{nbdns.RootZone}, handler, PriorityFallback)
// Wire a bypass resolver into the mgmt cache so its refresh path dials
// the original nameservers directly over a fwmarked socket, avoiding
// the ENOKEY deadlock that occurs when an exit-node default route is
// installed on the overlay before its peer has handshaked. Scoped to
// the mgmt cache only: ordinary user DNS still flows through the
// normal upstream path.
if s.mgmtCacheResolver != nil {
s.mgmtCacheResolver.SetBypassResolver(mgmt.NewBypassResolver(bypassNameservers))
}
} }
func (s *DefaultServer) buildLocalHandlerUpdate(customZones []nbdns.CustomZone) ([]handlerWrapper, []nbdns.CustomZone, error) { func (s *DefaultServer) buildLocalHandlerUpdate(customZones []nbdns.CustomZone) ([]handlerWrapper, []nbdns.CustomZone, error) {