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Merge pull request #46262 from thaJeztah/libnetwork_resolv_cleanups

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libnetwork: resolve: assorted cleanups
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Sebastiaan van Stijn 2023-08-23 14:22:33 +02:00 • committed by GitHub
commit 389b21a341
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GPG key ID: 4AEE18F83AFDEB23
1 changed files with 41 additions and 46 deletions
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87
libnetwork/resolver.go
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@ -5,6 +5,7 @@ import (
"fmt"
"math/rand"
"net"
"strconv"
"strings"
"sync"
"time"
@ -199,10 +200,6 @@ func (r *Resolver) ResolverOptions() []string {
return []string{"ndots:0"}
}
func setCommonFlags(msg *dns.Msg) {
msg.RecursionAvailable = true
}
//nolint:gosec // The RNG is not used in a security-sensitive context.
var (
shuffleRNG = rand.New(rand.NewSource(time.Now().Unix()))
@ -220,9 +217,9 @@ func shuffleAddr(addr []net.IP) []net.IP {
}
func createRespMsg(query *dns.Msg) *dns.Msg {
resp := new(dns.Msg)
resp := &dns.Msg{}
resp.SetReply(query)
setCommonFlags(resp)
resp.RecursionAvailable = true
return resp
}
@ -270,17 +267,17 @@ func (r *Resolver) handleIPQuery(query *dns.Msg, ipType int) (*dns.Msg, error) {
}
if ipType == types.IPv4 {
for _, ip := range addr {
rr := new(dns.A)
rr.Hdr = dns.RR_Header{Name: name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: respTTL}
rr.A = ip
resp.Answer = append(resp.Answer, rr)
resp.Answer = append(resp.Answer, &dns.A{
Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: respTTL},
A: ip,
})
}
} else {
for _, ip := range addr {
rr := new(dns.AAAA)
rr.Hdr = dns.RR_Header{Name: name, Rrtype: dns.TypeAAAA, Class: dns.ClassINET, Ttl: respTTL}
rr.AAAA = ip
resp.Answer = append(resp.Answer, rr)
resp.Answer = append(resp.Answer, &dns.AAAA{
Hdr: dns.RR_Header{Name: name, Rrtype: dns.TypeAAAA, Class: dns.ClassINET, Ttl: respTTL},
AAAA: ip,
})
}
}
return resp, nil
@ -306,14 +303,11 @@ func (r *Resolver) handlePTRQuery(query *dns.Msg) (*dns.Msg, error) {
r.log().Debugf("[resolver] lookup for IP %s: name %s", name, host)
fqdn := dns.Fqdn(host)
resp := new(dns.Msg)
resp.SetReply(query)
setCommonFlags(resp)
rr := new(dns.PTR)
rr.Hdr = dns.RR_Header{Name: ptr, Rrtype: dns.TypePTR, Class: dns.ClassINET, Ttl: respTTL}
rr.Ptr = fqdn
resp.Answer = append(resp.Answer, rr)
resp := createRespMsg(query)
resp.Answer = append(resp.Answer, &dns.PTR{
Hdr: dns.RR_Header{Name: ptr, Rrtype: dns.TypePTR, Class: dns.ClassINET, Ttl: respTTL},
Ptr: fqdn,
})
return resp, nil
}
@ -331,16 +325,15 @@ func (r *Resolver) handleSRVQuery(query *dns.Msg) (*dns.Msg, error) {
resp := createRespMsg(query)
for i, r := range srv {
rr := new(dns.SRV)
rr.Hdr = dns.RR_Header{Name: svc, Rrtype: dns.TypePTR, Class: dns.ClassINET, Ttl: respTTL}
rr.Port = r.Port
rr.Target = r.Target
resp.Answer = append(resp.Answer, rr)
rr1 := new(dns.A)
rr1.Hdr = dns.RR_Header{Name: r.Target, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: respTTL}
rr1.A = ip[i]
resp.Extra = append(resp.Extra, rr1)
resp.Answer = append(resp.Answer, &dns.SRV{
Hdr: dns.RR_Header{Name: svc, Rrtype: dns.TypePTR, Class: dns.ClassINET, Ttl: respTTL},
Port: r.Port,
Target: r.Target,
})
resp.Extra = append(resp.Extra, &dns.A{
Hdr: dns.RR_Header{Name: r.Target, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: respTTL},
A: ip[i],
})
}
return resp, nil
}
@ -425,26 +418,28 @@ func (r *Resolver) serveDNS(w dns.ResponseWriter, query *dns.Msg) {
reply(resp)
}
const defaultPort = "53"
func (r *Resolver) dialExtDNS(proto string, server extDNSEntry) (net.Conn, error) {
port := defaultPort
if server.port != 0 {
port = strconv.FormatUint(uint64(server.port), 10)
}
addr := net.JoinHostPort(server.IPStr, port)
if server.HostLoopback {
return net.DialTimeout(proto, addr, extIOTimeout)
}
var (
extConn net.Conn
dialErr error
)
extConnect := func() {
if server.port == 0 {
server.port = 53
}
addr := fmt.Sprintf("%s:%d", server.IPStr, server.port)
err := r.backend.ExecFunc(func() {
extConn, dialErr = net.DialTimeout(proto, addr, extIOTimeout)
}
if server.HostLoopback {
extConnect()
} else {
execErr := r.backend.ExecFunc(extConnect)
if execErr != nil {
return nil, execErr
}
})
if err != nil {
return nil, err
}
if dialErr != nil {
return nil, dialErr