dns: add edns0 subnet option support
This commit is contained in:
ginuerzh
parent
8121e20cbd
commit
cbc9c1f77e
@ -557,6 +557,8 @@ func (r *route) GenRouters() ([]router, error) {
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gost.ChainResolverOption(chain),
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gost.TimeoutResolverOption(timeout),
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gost.TTLResolverOption(ttl),
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gost.PreferResolverOption(node.Get("prefer")),
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gost.SrcIPResolverOption(net.ParseIP(node.Get("ip"))),
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)
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}
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112
resolver.go
112
resolver.go
@ -5,6 +5,7 @@ import (
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"bytes"
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"context"
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"crypto/tls"
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"errors"
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"fmt"
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"io"
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"io/ioutil"
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@ -122,6 +123,8 @@ type resolverOptions struct {
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chain *Chain
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timeout time.Duration
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ttl time.Duration
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prefer string
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srcIP net.IP
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}
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// ResolverOption allows a common way to set Resolver options.
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@ -148,6 +151,20 @@ func TTLResolverOption(ttl time.Duration) ResolverOption {
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}
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}
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// PreferResolverOption sets the prefer for Resolver.
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func PreferResolverOption(prefer string) ResolverOption {
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return func(opts *resolverOptions) {
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opts.prefer = prefer
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}
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}
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// SrcIPResolverOption sets the source IP for Resolver.
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func SrcIPResolverOption(ip net.IP) ResolverOption {
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return func(opts *resolverOptions) {
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opts.srcIP = ip
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}
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}
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// Resolver is a name resolver for domain name.
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// It contains a list of name servers.
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type Resolver interface {
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@ -177,6 +194,7 @@ type resolver struct {
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stopped chan struct{}
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mux sync.RWMutex
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prefer string // ipv4 or ipv6
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srcIP net.IP // for edns0 subnet option
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options resolverOptions
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}
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@ -217,6 +235,12 @@ func (r *resolver) Init(opts ...ResolverOption) error {
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if r.options.ttl != 0 {
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r.ttl = r.options.ttl
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}
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if r.options.prefer != "" {
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r.prefer = r.options.prefer
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}
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if r.options.srcIP != nil {
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r.srcIP = r.options.srcIP
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}
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var nss []NameServer
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for _, ns := range r.servers {
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@ -259,8 +283,9 @@ func (r *resolver) Resolve(host string) (ips []net.IP, err error) {
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host = host + "." + domain
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}
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ctx := context.Background()
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for _, ns := range r.copyServers() {
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ips, err = r.resolve(ns.exchanger, host)
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ips, err = r.resolve(ctx, ns.exchanger, host)
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if err != nil {
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log.Logf("[resolver] %s via %s : %s", host, ns.String(), err)
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continue
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@ -277,7 +302,7 @@ func (r *resolver) Resolve(host string) (ips []net.IP, err error) {
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return
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}
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func (r *resolver) resolve(ex Exchanger, host string) (ips []net.IP, err error) {
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func (r *resolver) resolve(ctx context.Context, ex Exchanger, host string) (ips []net.IP, err error) {
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if ex == nil {
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return
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}
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@ -286,7 +311,6 @@ func (r *resolver) resolve(ex Exchanger, host string) (ips []net.IP, err error)
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prefer := r.prefer
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r.mux.RUnlock()
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ctx := context.Background()
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if prefer == "ipv6" { // prefer ipv6
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mq := &dns.Msg{}
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mq.SetQuestion(dns.Fqdn(host), dns.TypeAAAA)
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@ -302,10 +326,16 @@ func (r *resolver) resolve(ex Exchanger, host string) (ips []net.IP, err error)
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}
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func (r *resolver) resolveIPs(ctx context.Context, ex Exchanger, mq *dns.Msg) (ips []net.IP, err error) {
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mr, _, err := r.exchangeMsg(ctx, ex, mq)
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key := newResolverCacheKey(&mq.Question[0])
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mr := r.cache.loadCache(key)
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if mr == nil {
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r.addSubnetOpt(mq)
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mr, err = r.exchangeMsg(ctx, ex, mq)
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if err != nil {
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return
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}
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r.cache.storeCache(key, mr, r.TTL())
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}
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for _, ans := range mr.Answer {
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if ar, _ := ans.(*dns.AAAA); ar != nil {
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@ -319,22 +349,61 @@ func (r *resolver) resolveIPs(ctx context.Context, ex Exchanger, mq *dns.Msg) (i
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return
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}
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func (r *resolver) addSubnetOpt(m *dns.Msg) {
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if m == nil || r.srcIP == nil {
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return
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}
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opt := new(dns.OPT)
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opt.Hdr.Name = "."
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opt.Hdr.Rrtype = dns.TypeOPT
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e := new(dns.EDNS0_SUBNET)
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e.Code = dns.EDNS0SUBNET
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if ip := r.srcIP.To4(); ip != nil {
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e.Family = 1
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e.SourceNetmask = 32
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e.Address = ip.To4()
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} else {
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e.Family = 2
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e.SourceNetmask = 128
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e.Address = r.srcIP
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}
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opt.Option = append(opt.Option, e)
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m.Extra = append(m.Extra, opt)
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}
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func (r *resolver) Exchange(ctx context.Context, query []byte) (reply []byte, err error) {
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mq := &dns.Msg{}
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if err = mq.Unpack(query); err != nil {
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return
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}
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var qs string
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if len(mq.Question) > 0 {
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qs = mq.Question[0].String()
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if len(mq.Question) == 0 {
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return nil, errors.New("empty question")
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}
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var mr *dns.Msg
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// Only cache for single question.
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if len(mq.Question) == 1 {
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key := newResolverCacheKey(&mq.Question[0])
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mr = r.cache.loadCache(key)
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if mr != nil {
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log.Logf("[dns] exchange message %d (cached): %s", mq.Id, mq.Question[0].String())
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mr.Id = mq.Id
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return mr.Pack()
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}
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defer func() {
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if mr != nil {
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r.cache.storeCache(key, mr, r.TTL())
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}
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}()
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}
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r.addSubnetOpt(mq)
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for _, ns := range r.copyServers() {
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var cache bool
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mr, cache, err = r.exchangeMsg(ctx, ns.exchanger, mq)
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log.Logf("[dns] exchange message %d via %s (cache hit: %v): %s", mq.Id, ns.String(), cache, qs)
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log.Logf("[dns] exchange message %d via %s: %s", mq.Id, ns.String(), mq.Question[0].String())
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mr, err = r.exchangeMsg(ctx, ns.exchanger, mq)
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if err == nil {
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break
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}
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@ -346,22 +415,7 @@ func (r *resolver) Exchange(ctx context.Context, query []byte) (reply []byte, er
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return mr.Pack()
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}
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func (r *resolver) exchangeMsg(ctx context.Context, ex Exchanger, mq *dns.Msg) (mr *dns.Msg, cache bool, err error) {
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// Only cache for single question.
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if len(mq.Question) == 1 {
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key := newResolverCacheKey(&mq.Question[0])
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mr = r.cache.loadCache(key)
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if mr != nil {
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cache = true
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mr.Id = mq.Id
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return
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}
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defer func() {
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r.cache.storeCache(key, mr, r.TTL())
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}()
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}
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func (r *resolver) exchangeMsg(ctx context.Context, ex Exchanger, mq *dns.Msg) (mr *dns.Msg, err error) {
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query, err := mq.Pack()
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if err != nil {
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return
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@ -386,6 +440,7 @@ func (r *resolver) TTL() time.Duration {
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func (r *resolver) Reload(rd io.Reader) error {
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var ttl, timeout, period time.Duration
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var domain, prefer string
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var srcIP net.IP
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var nss []NameServer
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if rd == nil || r.Stopped() {
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@ -422,6 +477,10 @@ func (r *resolver) Reload(rd io.Reader) error {
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if len(ss) > 1 {
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prefer = strings.ToLower(ss[1])
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}
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case "ip":
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if len(ss) > 1 {
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srcIP = net.ParseIP(ss[1])
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}
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case "nameserver": // nameserver option, compatible with /etc/resolv.conf
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if len(ss) <= 1 {
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break
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@ -461,6 +520,7 @@ func (r *resolver) Reload(rd io.Reader) error {
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r.domain = domain
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r.period = period
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r.prefer = prefer
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r.srcIP = srcIP
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r.servers = nss
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r.mux.Unlock()
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