Add TCP/TLS pipelining dns resolver

resolver/resolver-pooled_test.go

@@ -0,0 +1,83 @@
+package resolver
+
+import (
+	"sync"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/miekg/dns"
+)
+
+func testQuery(t *testing.T, wg *sync.WaitGroup, newCnt *uint32, brc *BasicResolverConn, q *Query) {
+	dnsClient := brc.clientManager.getDNSClient()
+
+	// create query
+	dnsQuery := new(dns.Msg)
+	dnsQuery.SetQuestion(q.FQDN, uint16(q.QType))
+
+	// get connection
+	conn, new, err := dnsClient.getConn()
+	if err != nil {
+		t.Logf("failed to connect: %s", err) //nolint:staticcheck
+		wg.Done()
+		return
+	}
+	if new {
+		atomic.AddUint32(newCnt, 1)
+	}
+
+	// query server
+	reply, ttl, err := dnsClient.client.ExchangeWithConn(dnsQuery, conn)
+	if err != nil {
+		t.Logf("client failed: %s", err) //nolint:staticcheck
+		wg.Done()
+		return
+	}
+	if reply == nil {
+		t.Fatalf("resolved %s, but reply was empty!", q.FQDN) //nolint:staticcheck
+	}
+
+	t.Logf("resolved %s [new resolver = %v] in %s", q.FQDN, new, ttl)
+	dnsClient.addToPool()
+	wg.Done()
+}
+
+func TestClientPooling(t *testing.T) {
+	// skip if short - this test depends on the Internet and might fail randomly
+	if testing.Short() {
+		t.Skip()
+	}
+
+	// create separate resolver for this test
+	resolver, _, err := createResolver("dot://9.9.9.9:853?verify=dns.quad9.net&name=Quad9&blockedif=empty", "config")
+	// resolver, _, err := createResolver("dot://1.1.1.2:853?verify=cloudflare-dns.com&name=Cloudflare&blockedif=zeroip", "config")
+	if err != nil {
+		t.Fatal(err)
+	}
+	brc := &BasicResolverConn{
+		clientManager: clientManagerFactory(resolver.ServerType)(resolver),
+		resolver:      resolver,
+	}
+	resolver.Conn = brc
+
+	started := time.Now()
+
+	wg := &sync.WaitGroup{}
+	var newCnt uint32
+	for i := 0; i < 10; i++ {
+		wg.Add(10)
+		for j := 0; j < 10; j++ {
+			go testQuery(t, wg, &newCnt, brc, &Query{ //nolint:staticcheck
+				FQDN:  <-domainFeed,
+				QType: dns.Type(dns.TypeA),
+			})
+		}
+		wg.Wait()
+		if newCnt > uint32(10+i) {
+			t.Fatalf("unexpected pool size: %d (limit is %d)", newCnt, 10+i)
+		}
+	}
+
+	t.Logf("time taken: %s", time.Since(started))
+}