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Improve resilience and logging in resolver and nameserver

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This commit is contained in:
Daniel 2020-08-17 22:17:48 +02:00
parent 633bb34288
commit 39aa3d0879
3 changed files with 35 additions and 16 deletions
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20
nameserver/nameserver.go
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@ -3,6 +3,7 @@ package nameserver
import (
"context"
"errors"
"fmt"
"net"
"strings"
@ -91,7 +92,7 @@ func stop() error {
func returnServerFailure(w dns.ResponseWriter, query *dns.Msg) {
m := new(dns.Msg)
m.SetRcode(query, dns.RcodeServerFailure)
_ = w.WriteMsg(m)
_ = writeDNSResponse(w, m)
}
func handleRequestAsWorker(w dns.ResponseWriter, query *dns.Msg) {
@ -132,7 +133,7 @@ func handleRequest(ctx context.Context, w dns.ResponseWriter, query *dns.Msg) er
m := new(dns.Msg)
m.SetReply(query)
m.Answer = localhostRRs
if err := w.WriteMsg(m); err != nil {
if err := writeDNSResponse(w, m); err != nil {
log.Warningf("nameserver: failed to handle request to %s: %s", q.FQDN, err)
}
return nil
@ -270,7 +271,7 @@ func handleRequest(ctx context.Context, w dns.ResponseWriter, query *dns.Msg) er
m.Ns = rrCache.Ns
m.Extra = rrCache.Extra
if err := w.WriteMsg(m); err != nil {
if err := writeDNSResponse(w, m); err != nil {
tracer.Warningf("nameserver: failed to return response %s%s to %s: %s", q.FQDN, q.QType, conn.Process(), err)
} else {
tracer.Debugf("nameserver: returning response %s%s to %s", q.FQDN, q.QType, conn.Process())
@ -281,3 +282,16 @@ func handleRequest(ctx context.Context, w dns.ResponseWriter, query *dns.Msg) er
return nil
}
func writeDNSResponse(w dns.ResponseWriter, m *dns.Msg) (err error) {
defer func() {
// recover from panic
if panicErr := recover(); panicErr != nil {
err = fmt.Errorf("panic: %s", panicErr)
log.Warningf("nameserver: panic caused by this msg: %#v", m)
}
}()
err = w.WriteMsg(m)
return
}

2
nameserver/response.go
View file

@ -30,7 +30,7 @@ func sendResponse(w dns.ResponseWriter, query *dns.Msg, verdict network.Verdict,
reply.Extra = append(reply.Extra, rrs...)
}
if err := w.WriteMsg(reply); err != nil {
if err := writeDNSResponse(w, reply); err != nil {
log.Errorf("nameserver: failed to send response: %s", err)
}
}

29
resolver/rrcache.go
View file

@ -7,6 +7,7 @@ import (
"sync"
"time"
"github.com/safing/portbase/log"
"github.com/safing/portmaster/netenv"
"github.com/miekg/dns"
@ -163,22 +164,13 @@ func GetRRCache(domain string, question dns.Type) (*RRCache, error) {
rrCache.TTL = nameRecord.TTL
for _, entry := range nameRecord.Answer {
rr, err := dns.NewRR(entry)
if err == nil {
rrCache.Answer = append(rrCache.Answer, rr)
}
rrCache.Answer = parseRR(rrCache.Answer, entry)
}
for _, entry := range nameRecord.Ns {
rr, err := dns.NewRR(entry)
if err == nil {
rrCache.Ns = append(rrCache.Ns, rr)
}
rrCache.Ns = parseRR(rrCache.Ns, entry)
}
for _, entry := range nameRecord.Extra {
rr, err := dns.NewRR(entry)
if err == nil {
rrCache.Extra = append(rrCache.Extra, rr)
}
rrCache.Extra = parseRR(rrCache.Extra, entry)
}
rrCache.Server = nameRecord.Server
@ -187,6 +179,19 @@ func GetRRCache(domain string, question dns.Type) (*RRCache, error) {
return rrCache, nil
}
func parseRR(section []dns.RR, entry string) []dns.RR {
rr, err := dns.NewRR(entry)
switch {
case err != nil:
log.Warningf("resolver: failed to parse cached record %q: %s", entry, err)
case rr == nil:
log.Warningf("resolver: failed to parse cached record %q: resulted in nil record", entry)
default:
return append(section, rr)
}
return section
}
// ServedFromCache marks the RRCache as served from cache.
func (rrCache *RRCache) ServedFromCache() bool {
return rrCache.servedFromCache