func (c Chaos) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
state := middleware.State{W: w, Req: r}
if state.QClass() != dns.ClassCHAOS || state.QType() != dns.TypeTXT {
return c.Next.ServeDNS(ctx, w, r)
}
m := new(dns.Msg)
m.SetReply(r)
hdr := dns.RR_Header{Name: state.QName(), Rrtype: dns.TypeTXT, Class: dns.ClassCHAOS, Ttl: 0}
switch state.Name() {
default:
return c.Next.ServeDNS(ctx, w, r)
case "authors.bind.":
for a, _ := range c.Authors {
m.Answer = append(m.Answer, &dns.TXT{Hdr: hdr, Txt: []string{trim(a)}})
}
case "version.bind.", "version.server.":
m.Answer = []dns.RR{&dns.TXT{Hdr: hdr, Txt: []string{trim(c.Version)}}}
case "hostname.bind.", "id.server.":
hostname, err := os.Hostname()
if err != nil {
hostname = "localhost"
}
m.Answer = []dns.RR{&dns.TXT{Hdr: hdr, Txt: []string{trim(hostname)}}}
}
state.SizeAndDo(m)
w.WriteMsg(m)
return 0, nil
}
// ServeDNS implements the middleware.Handler interface.
func (d Dnssec) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
state := middleware.State{W: w, Req: r}
do := state.Do()
qname := state.Name()
qtype := state.QType()
zone := middleware.Zones(d.zones).Matches(qname)
if zone == "" {
return d.Next.ServeDNS(ctx, w, r)
}
// Intercept queries for DNSKEY, but only if one of the zones matches the qname, otherwise we let
// the query through.
if qtype == dns.TypeDNSKEY {
for _, z := range d.zones {
if qname == z {
resp := d.getDNSKEY(state, z, do)
state.SizeAndDo(resp)
w.WriteMsg(resp)
return dns.RcodeSuccess, nil
}
}
}
drr := NewDnssecResponseWriter(w, d)
return d.Next.ServeDNS(ctx, drr, r)
}
func (l Logger) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
state := middleware.State{W: w, Req: r}
for _, rule := range l.Rules {
if middleware.Name(rule.NameScope).Matches(state.Name()) {
responseRecorder := middleware.NewResponseRecorder(w)
rcode, err := l.Next.ServeDNS(ctx, responseRecorder, r)
if rcode > 0 {
// There was an error up the chain, but no response has been written yet.
// The error must be handled here so the log entry will record the response size.
if l.ErrorFunc != nil {
l.ErrorFunc(responseRecorder, r, rcode)
} else {
rc := middleware.RcodeToString(rcode)
answer := new(dns.Msg)
answer.SetRcode(r, rcode)
state.SizeAndDo(answer)
metrics.Report(state, metrics.Dropped, rc, answer.Len(), time.Now())
w.WriteMsg(answer)
}
rcode = 0
}
rep := middleware.NewReplacer(r, responseRecorder, CommonLogEmptyValue)
rule.Log.Println(rep.Replace(rule.Format))
return rcode, err
}
}
return l.Next.ServeDNS(ctx, w, r)
}
// ServeDNS implements the middleware.Handler interface.
func (c Cache) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
state := middleware.State{W: w, Req: r}
qname := state.Name()
qtype := state.QType()
zone := middleware.Zones(c.Zones).Matches(qname)
if zone == "" {
return c.Next.ServeDNS(ctx, w, r)
}
do := state.Do() // might need more from OPT record?
if i, ok := c.get(qname, qtype, do); ok {
resp := i.toMsg(r)
state.SizeAndDo(resp)
w.WriteMsg(resp)
cacheHitCount.WithLabelValues(zone).Inc()
return dns.RcodeSuccess, nil
}
cacheMissCount.WithLabelValues(zone).Inc()
crr := NewCachingResponseWriter(w, c.cache, c.cap)
return c.Next.ServeDNS(ctx, crr, r)
}
// NoData write a nodata response to the client.
func (k Kubernetes) Err(zone string, rcode int, state middleware.State) (int, error) {
m := new(dns.Msg)
m.SetRcode(state.Req, rcode)
m.Ns = []dns.RR{k.SOA(zone, state)}
state.SizeAndDo(m)
state.W.WriteMsg(m)
return rcode, nil
}
// DefaultErrorFunc responds to an DNS request with an error.
func DefaultErrorFunc(w dns.ResponseWriter, r *dns.Msg, rcode int) {
state := middleware.State{W: w, Req: r}
rc := middleware.RcodeToString(rcode)
answer := new(dns.Msg)
answer.SetRcode(r, rcode)
state.SizeAndDo(answer)
metrics.Report(state, metrics.Dropped, rc, answer.Len(), time.Now())
w.WriteMsg(answer)
}
func (h ErrorHandler) recovery(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) {
rec := recover()
if rec == nil {
return
}
state := middleware.State{W: w, Req: r}
// Obtain source of panic
// From: https://gist.github.com/swdunlop/9629168
var name, file string // function name, file name
var line int
var pc [16]uintptr
n := runtime.Callers(3, pc[:])
for _, pc := range pc[:n] {
fn := runtime.FuncForPC(pc)
if fn == nil {
continue
}
file, line = fn.FileLine(pc)
name = fn.Name()
if !strings.HasPrefix(name, "runtime.") {
break
}
}
// Trim file path
delim := "/coredns/"
pkgPathPos := strings.Index(file, delim)
if pkgPathPos > -1 && len(file) > pkgPathPos+len(delim) {
file = file[pkgPathPos+len(delim):]
}
panicMsg := fmt.Sprintf("%s [PANIC %s %s] %s:%d - %v", time.Now().Format(timeFormat), r.Question[0].Name, dns.Type(r.Question[0].Qtype), file, line, rec)
if h.Debug {
// Write error and stack trace to the response rather than to a log
var stackBuf [4096]byte
stack := stackBuf[:runtime.Stack(stackBuf[:], false)]
answer := debugMsg(dns.RcodeServerFailure, r)
// add stack buf in TXT, limited to 255 chars for now.
txt, _ := dns.NewRR(". IN 0 TXT " + string(stack[:255]))
answer.Answer = append(answer.Answer, txt)
state.SizeAndDo(answer)
w.WriteMsg(answer)
} else {
// Currently we don't use the function name, since file:line is more conventional
h.Log.Printf(panicMsg)
}
}
// Err write an error response to the client.
func (e Etcd) Err(zone string, rcode int, state middleware.State, debug []msg.Service, err error) (int, error) {
m := new(dns.Msg)
m.SetRcode(state.Req, rcode)
m.Authoritative, m.RecursionAvailable, m.Compress = true, true, true
m.Ns, _, _ = e.SOA(zone, state)
if e.debug != "" {
m.Extra = servicesToTxt(debug)
txt := errorToTxt(err)
if txt != nil {
m.Extra = append(m.Extra, errorToTxt(err))
}
}
state.SizeAndDo(m)
state.W.WriteMsg(m)
// Return success as the rcode to signal we have written to the client.
return dns.RcodeSuccess, nil
}
func (d *DnssecResponseWriter) WriteMsg(res *dns.Msg) error {
// By definition we should sign anything that comes back, we should still figure out for
// which zone it should be.
state := middleware.State{W: d.ResponseWriter, Req: res}
qname := state.Name()
zone := middleware.Zones(d.d.zones).Matches(qname)
if zone == "" {
return d.ResponseWriter.WriteMsg(res)
}
if state.Do() {
res = d.d.Sign(state, zone, time.Now().UTC())
}
state.SizeAndDo(res)
return d.ResponseWriter.WriteMsg(res)
}
func (s Stub) ServeDNS(ctx context.Context, w dns.ResponseWriter, req *dns.Msg) (int, error) {
if hasStubEdns0(req) {
log.Printf("[WARNING] Forwarding cycle detected, refusing msg: %s", req.Question[0].Name)
return dns.RcodeRefused, errors.New("stub forward cycle")
}
req = addStubEdns0(req)
proxy, ok := (*s.Etcd.Stubmap)[s.Zone]
if !ok { // somebody made a mistake..
return dns.RcodeServerFailure, nil
}
state := middleware.State{W: w, Req: req}
m, e := proxy.Forward(state)
if e != nil {
return dns.RcodeServerFailure, e
}
m.RecursionAvailable, m.Compress = true, true
state.SizeAndDo(m)
w.WriteMsg(m)
return dns.RcodeSuccess, nil
}
func (h ErrorHandler) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
defer h.recovery(ctx, w, r)
rcode, err := h.Next.ServeDNS(ctx, w, r)
if err != nil {
state := middleware.State{W: w, Req: r}
errMsg := fmt.Sprintf("%s [ERROR %d %s %s] %v", time.Now().Format(timeFormat), rcode, state.Name(), state.Type(), err)
if h.Debug {
// Write error to response as a txt message instead of to log
answer := debugMsg(rcode, r)
txt, _ := dns.NewRR(". IN 0 TXT " + errMsg)
answer.Answer = append(answer.Answer, txt)
state.SizeAndDo(answer)
w.WriteMsg(answer)
return 0, err
}
h.Log.Println(errMsg)
}
return rcode, err
}
// Lookup will use name and type to forge a new message and will send that upstream. It will
// set any EDNS0 options correctly so that downstream will be able to process the reply.
// Lookup is not suitable for forwarding request. Ssee for that.
func (p Proxy) Lookup(state middleware.State, name string, tpe uint16) (*dns.Msg, error) {
req := new(dns.Msg)
req.SetQuestion(name, tpe)
state.SizeAndDo(req)
return p.lookup(state, req)
}
func (e Etcd) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
state := middleware.State{W: w, Req: r}
if state.QClass() != dns.ClassINET {
return dns.RcodeServerFailure, fmt.Errorf("can only deal with ClassINET")
}
name := state.Name()
if e.Debug {
if debug := isDebug(name); debug != "" {
e.debug = r.Question[0].Name
state.Clear()
state.Req.Question[0].Name = debug
}
}
// We need to check stubzones first, because we may get a request for a zone we
// are not auth. for *but* do have a stubzone forward for. If we do the stubzone
// handler will handle the request.
if e.Stubmap != nil && len(*e.Stubmap) > 0 {
for zone := range *e.Stubmap {
if middleware.Name(zone).Matches(name) {
stub := Stub{Etcd: e, Zone: zone}
return stub.ServeDNS(ctx, w, r)
}
}
}
zone := middleware.Zones(e.Zones).Matches(state.Name())
if zone == "" {
if e.Next == nil {
return dns.RcodeServerFailure, nil
}
return e.Next.ServeDNS(ctx, w, r)
}
var (
records, extra []dns.RR
debug []msg.Service
err error
)
switch state.Type() {
case "A":
records, debug, err = e.A(zone, state, nil)
case "AAAA":
records, debug, err = e.AAAA(zone, state, nil)
case "TXT":
records, debug, err = e.TXT(zone, state)
case "CNAME":
records, debug, err = e.CNAME(zone, state)
case "PTR":
records, debug, err = e.PTR(zone, state)
case "MX":
records, extra, debug, err = e.MX(zone, state)
case "SRV":
records, extra, debug, err = e.SRV(zone, state)
case "SOA":
records, debug, err = e.SOA(zone, state)
case "NS":
if state.Name() == zone {
records, extra, debug, err = e.NS(zone, state)
break
}
fallthrough
default:
// Do a fake A lookup, so we can distinguish between NODATA and NXDOMAIN
_, debug, err = e.A(zone, state, nil)
}
if e.debug != "" {
// Substitute this name with the original when we return the request.
state.Clear()
state.Req.Question[0].Name = e.debug
}
if isEtcdNameError(err) {
return e.Err(zone, dns.RcodeNameError, state, debug, err)
}
if err != nil {
return e.Err(zone, dns.RcodeServerFailure, state, debug, err)
}
if len(records) == 0 {
return e.Err(zone, dns.RcodeSuccess, state, debug, err)
}
m := new(dns.Msg)
m.SetReply(r)
m.Authoritative, m.RecursionAvailable, m.Compress = true, true, true
m.Answer = append(m.Answer, records...)
m.Extra = append(m.Extra, extra...)
if e.debug != "" {
m.Extra = append(m.Extra, servicesToTxt(debug)...)
}
m = dedup(m)
state.SizeAndDo(m)
m, _ = state.Scrub(m)
w.WriteMsg(m)
return dns.RcodeSuccess, nil
}
func (f File) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
state := middleware.State{W: w, Req: r}
if state.QClass() != dns.ClassINET {
return dns.RcodeServerFailure, errors.New("can only deal with ClassINET")
}
qname := state.Name()
zone := middleware.Zones(f.Zones.Names).Matches(qname)
if zone == "" {
if f.Next != nil {
return f.Next.ServeDNS(ctx, w, r)
}
return dns.RcodeServerFailure, errors.New("no next middleware found")
}
z, ok := f.Zones.Z[zone]
if !ok {
return f.Next.ServeDNS(ctx, w, r)
}
if z == nil {
return dns.RcodeServerFailure, nil
}
if r.Opcode == dns.OpcodeNotify {
if z.isNotify(state) {
m := new(dns.Msg)
m.SetReply(r)
m.Authoritative, m.RecursionAvailable, m.Compress = true, true, true
state.SizeAndDo(m)
w.WriteMsg(m)
log.Printf("[INFO] Notify from %s for %s: checking transfer", state.IP(), zone)
ok, err := z.shouldTransfer()
if ok {
z.TransferIn()
} else {
log.Printf("[INFO] Notify from %s for %s: no serial increase seen", state.IP(), zone)
}
if err != nil {
log.Printf("[WARNING] Notify from %s for %s: failed primary check: %s", state.IP(), zone, err)
}
return dns.RcodeSuccess, nil
}
log.Printf("[INFO] Dropping notify from %s for %s", state.IP(), zone)
return dns.RcodeSuccess, nil
}
if z.Expired != nil && *z.Expired {
log.Printf("[ERROR] Zone %s is expired", zone)
return dns.RcodeServerFailure, nil
}
if state.QType() == dns.TypeAXFR || state.QType() == dns.TypeIXFR {
xfr := Xfr{z}
return xfr.ServeDNS(ctx, w, r)
}
answer, ns, extra, result := z.Lookup(qname, state.QType(), state.Do())
m := new(dns.Msg)
m.SetReply(r)
m.Authoritative, m.RecursionAvailable, m.Compress = true, true, true
m.Answer, m.Ns, m.Extra = answer, ns, extra
switch result {
case Success:
case NoData:
case NameError:
m.Rcode = dns.RcodeNameError
case Delegation:
m.Authoritative = false
case ServerFailure:
return dns.RcodeServerFailure, nil
}
state.SizeAndDo(m)
m, _ = state.Scrub(m)
w.WriteMsg(m)
return dns.RcodeSuccess, nil
}
func (k Kubernetes) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
log.Printf("[debug] here entering ServeDNS: ctx:%v dnsmsg:%v\n", ctx, r)
state := middleware.State{W: w, Req: r}
if state.QClass() != dns.ClassINET {
return dns.RcodeServerFailure, fmt.Errorf("can only deal with ClassINET")
}
// Check that query matches one of the zones served by this middleware,
// otherwise delegate to the next in the pipeline.
zone := middleware.Zones(k.Zones).Matches(state.Name())
if zone == "" {
if k.Next == nil {
return dns.RcodeServerFailure, nil
}
return k.Next.ServeDNS(ctx, w, r)
}
m := new(dns.Msg)
m.SetReply(r)
m.Authoritative, m.RecursionAvailable, m.Compress = true, true, true
var (
records, extra []dns.RR
err error
)
switch state.Type() {
case "A":
records, err = k.A(zone, state, nil)
case "AAAA":
records, err = k.AAAA(zone, state, nil)
case "TXT":
records, err = k.TXT(zone, state)
// TODO: change lookup to return appropriate error. Then add code below
// this switch to check for the error and return not implemented.
//return dns.RcodeNotImplemented, nil
case "CNAME":
records, err = k.CNAME(zone, state)
case "MX":
records, extra, err = k.MX(zone, state)
case "SRV":
records, extra, err = k.SRV(zone, state)
case "SOA":
records = []dns.RR{k.SOA(zone, state)}
case "NS":
if state.Name() == zone {
records, extra, err = k.NS(zone, state)
break
}
fallthrough
default:
// Do a fake A lookup, so we can distinguish betwen NODATA and NXDOMAIN
_, err = k.A(zone, state, nil)
}
if isKubernetesNameError(err) {
return k.Err(zone, dns.RcodeNameError, state)
}
if err != nil {
return dns.RcodeServerFailure, err
}
if len(records) == 0 {
return k.Err(zone, dns.RcodeSuccess, state)
}
m.Answer = append(m.Answer, records...)
m.Extra = append(m.Extra, extra...)
m = dedup(m)
state.SizeAndDo(m)
m, _ = state.Scrub(m)
w.WriteMsg(m)
return dns.RcodeSuccess, nil
}