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Using ControlD bootstrap DNS again

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So on system where there's no available DNS, non-ControlD upstreams
could be bootstrapped like before.

While at it, also improving lookupIP to not initializing OS resolver
anymore, removing the un-necessary contention for accquiring/releasing
OS resolver mutex.
This commit is contained in:
Cuong Manh Le
2025-04-14 22:58:04 +07:00
committed by Cuong Manh Le
parent 8d6ea91f35
commit 0c2cc00c4f
2 changed files with 24 additions and 13 deletions
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14
config.go
View File

@@ -427,11 +427,18 @@ func (uc *UpstreamConfig) UID() string {
// SetupBootstrapIP manually find all available IPs of the upstream.
// The first usable IP will be used as bootstrap IP of the upstream.
// The upstream domain will be looked up using following orders:
//
// - Current system DNS settings.
// - Direct IPs table for ControlD upstreams.
// - ControlD Bootstrap DNS 76.76.2.22
//
// The setup process will block until there's usable IPs found.
func (uc *UpstreamConfig) SetupBootstrapIP() {
b := backoff.NewBackoff("setupBootstrapIP", func(format string, args ...any) {}, 10*time.Second)
isControlD := uc.IsControlD()
for {
uc.bootstrapIPs = lookupIP(uc.Domain, uc.Timeout)
uc.bootstrapIPs = lookupIP(uc.Domain, uc.Timeout, defaultNameservers())
// For ControlD upstream, the bootstrap IPs could not be RFC 1918 addresses,
// filtering them out here to prevent weird behavior.
if isControlD {
@@ -449,6 +456,11 @@ func (uc *UpstreamConfig) SetupBootstrapIP() {
ProxyLogger.Load().Warn().Msgf("no record found for %q, lookup from direct IP table", uc.Domain)
}
}
if len(uc.bootstrapIPs) == 0 {
ProxyLogger.Load().Warn().Msgf("no record found for %q, using bootstrap server: %s", uc.Domain, PremiumDNSBoostrapIP)
uc.bootstrapIPs = lookupIP(uc.Domain, uc.Timeout, []string{net.JoinHostPort(PremiumDNSBoostrapIP, "53")})
}
if len(uc.bootstrapIPs) > 0 {
break
}

23
resolver.go
View File

@@ -466,27 +466,26 @@ func (d dummyResolver) Resolve(ctx context.Context, msg *dns.Msg) (*dns.Msg, err
return ans, nil
}
// LookupIP looks up host using OS resolver.
// LookupIP looks up domain using current system nameservers settings.
// It returns a slice of that host's IPv4 and IPv6 addresses.
func LookupIP(domain string) []string {
return lookupIP(domain, -1)
return lookupIP(domain, -1, defaultNameservers())
}
func lookupIP(domain string, timeout int) (ips []string) {
// lookupIP looks up domain with given timeout and bootstrapDNS.
// If timeout is negative, default timeout 2000 ms will be used.
// It returns nil if bootstrapDNS is nil or empty.
func lookupIP(domain string, timeout int, bootstrapDNS []string) (ips []string) {
if net.ParseIP(domain) != nil {
return []string{domain}
}
resolverMutex.Lock()
if or == nil {
ProxyLogger.Load().Debug().Msgf("Initialize OS resolver in lookupIP")
or = newResolverWithNameserver(defaultNameservers())
if bootstrapDNS == nil {
ProxyLogger.Load().Debug().Msgf("empty bootstrap DNS")
return nil
}
nss := *or.lanServers.Load()
nss = append(nss, *or.publicServers.Load()...)
resolverMutex.Unlock()
resolver := newResolverWithNameserver(nss)
ProxyLogger.Load().Debug().Msgf("resolving %q using bootstrap DNS %q", domain, nss)
resolver := newResolverWithNameserver(bootstrapDNS)
ProxyLogger.Load().Debug().Msgf("resolving %q using bootstrap DNS %q", domain, bootstrapDNS)
timeoutMs := 2000
if timeout > 0 && timeout < timeoutMs {
timeoutMs = timeout