From: Dan Fuhry <dan@fuhry.com>
Date: Thu, 25 Apr 2024 04:05:07 +0000 (-0400)
Subject: dns cache: fix message headers, populate edns udp size
X-Git-Url: https://go.fuhry.dev/?a=commitdiff_plain;h=39feda1cdedf49196e605d11ea374f2e9bbd1844;p=runtime.git

dns cache: fix message headers, populate edns udp size
---

diff --git a/net/dns/dns_cache.go b/net/dns/dns_cache.go
index 4a3a6fa..2cd3237 100644
--- a/net/dns/dns_cache.go
+++ b/net/dns/dns_cache.go
@@ -4,11 +4,14 @@ import (
 	"context"
 	"fmt"
 	"math/rand"
+	"net"
 	"sync"
 	"time"
 
 	lru "github.com/hashicorp/golang-lru"
 	"github.com/miekg/dns"
+
+	"go.fuhry.dev/runtime/utils/log"
 )
 
 var dnsCache *lru.Cache
@@ -32,6 +35,7 @@ func ResolveDualStack(hostname string) (string, string, error) {
 		if msg, ok = entry.(*dns.Msg); !ok {
 			return "", "", fmt.Errorf("lru cache is corrupt: expected entry to be *dns.Msg, got %T", entry)
 		}
+		log.V(3).Debugf("cache hit for hostname %q: %+v", hostname, entry)
 	} else {
 		msg, err = doDualStackQuery(hostname)
 		if err != nil {
@@ -66,10 +70,14 @@ func doDualStackQuery(hostname string) (*dns.Msg, error) {
 		return nil, err
 	}
 
+	log.V(3).Debugf("cache miss, attempting dualstack dns query for hostname: %q", hostname)
+	log.V(3).Debugf("will resolve using DNS servers: %+v", cc.Servers)
 	for _, qtype := range []uint16{dns.TypeA, dns.TypeAAAA} {
 		query := &dns.Msg{
 			MsgHdr: dns.MsgHdr{
 				Id:                dns.Id(),
+				Opcode:            dns.OpcodeQuery,
+				Response:          false,
 				RecursionDesired:  true,
 				AuthenticatedData: true,
 			},
@@ -101,16 +109,18 @@ func doDualStackQuery(hostname string) (*dns.Msg, error) {
 		defer cancel()
 
 		for _, server := range cc.Servers {
-			go (func() {
-				m, _, err := client.Exchange(query, server+":53")
+			go (func(server string) {
+				start := time.Now()
+				m, _, err := client.Exchange(query, net.JoinHostPort(server, "53"))
 				if m != nil && err == nil {
 					mu.Lock()
 					defer mu.Unlock()
 					if !done {
+						log.V(2).Infof("resolved name %q to %v via DNS server %s in %s", hostname, m.Answer, server, time.Since(start))
 						resultChan <- m
 					}
 				}
-			})()
+			})(server)
 		}
 
 		select {
@@ -134,6 +144,7 @@ func newEDNSCookie() dns.RR {
 		Hdr: dns.RR_Header{
 			Name:   ".",
 			Rrtype: dns.TypeOPT,
+			Class:  1232,
 		},
 		Option: []dns.EDNS0{
 			&dns.EDNS0_COOKIE{
diff --git a/sase/happy_eyeballs.go b/sase/happy_eyeballs.go
index 5ebd07e..4e87c2e 100644
--- a/sase/happy_eyeballs.go
+++ b/sase/happy_eyeballs.go
@@ -63,6 +63,10 @@ func dialHappyEyeballs(ctx context.Context, addrs []net.Addr, port uint16) (net.
 		return nil, fmt.Errorf("cannot dial happy eyeballs connection: at least one address family must be enabled")
 	}
 
+	if len(addrs) < 1 {
+		return nil, fmt.Errorf("error dialing: no address associated with hostname")
+	}
+
 	logger.V(2).Debugf("ipv4: %t / ipv6: %t", ipv4Enable, ipv6Enable)
 
 	dialer := &net.Dialer{}