From 0a6890780df4708e7280168a603135bd8389d8d8 Mon Sep 17 00:00:00 2001
From: Norman Maurer <norman_maurer@apple.com>
Date: Mon, 19 Dec 2022 08:31:58 +0100
Subject: [PATCH] Make test more robust by binding the ServerSocket first
 (#13061)

Motivation:

Sometimes we saw failures due port already in use. Let's ensure we can bind to it before bootstrap the DnsServer

Modifications:

First bind the TCP socket

Result:

Hopefully less flaky test
---
 .../resolver/dns/DnsNameResolverTest.java     | 28 +++++++++++--------
 .../io/netty/resolver/dns/TestDnsServer.java  |  5 +++-
 2 files changed, 21 insertions(+), 12 deletions(-)

diff --git a/resolver-dns/src/test/java/io/netty/resolver/dns/DnsNameResolverTest.java b/resolver-dns/src/test/java/io/netty/resolver/dns/DnsNameResolverTest.java
index eea00bb62f23..6aac63c20ace 100644
--- a/resolver-dns/src/test/java/io/netty/resolver/dns/DnsNameResolverTest.java
+++ b/resolver-dns/src/test/java/io/netty/resolver/dns/DnsNameResolverTest.java
@@ -3079,6 +3079,14 @@ private static DnsMessageModifier modifierFrom(DnsMessage message) {
     }
 
     private static void testTruncated0(boolean tcpFallback, final boolean truncatedBecauseOfMtu) throws IOException {
+        ServerSocket serverSocket = null;
+        if (tcpFallback) {
+            // If we are configured to use TCP as a fallback also bind a TCP socket
+            serverSocket = new ServerSocket();
+            serverSocket.setReuseAddress(true);
+            serverSocket.bind(new InetSocketAddress(NetUtil.LOCALHOST4, 0));
+        }
+
         final String host = "somehost.netty.io";
         final String txt = "this is a txt record";
         final AtomicReference<DnsMessage> messageRef = new AtomicReference<DnsMessage>();
@@ -3110,24 +3118,22 @@ protected DnsMessage filterMessage(DnsMessage message) {
                 return message;
             }
         };
-        dnsServer2.start();
         DnsNameResolver resolver = null;
-        ServerSocket serverSocket = null;
         try {
-            DnsNameResolverBuilder builder = newResolver()
-                    .queryTimeoutMillis(10000)
-                    .resolvedAddressTypes(ResolvedAddressTypes.IPV4_PREFERRED)
-                    .maxQueriesPerResolve(16)
-                    .nameServerProvider(new SingletonDnsServerAddressStreamProvider(dnsServer2.localAddress()));
+            DnsNameResolverBuilder builder = newResolver();
 
             if (tcpFallback) {
-                // If we are configured to use TCP as a fallback also bind a TCP socket
-                serverSocket = new ServerSocket();
-                serverSocket.setReuseAddress(true);
-                serverSocket.bind(new InetSocketAddress(dnsServer2.localAddress().getPort()));
+                dnsServer2.start(false, (InetSocketAddress) serverSocket.getLocalSocketAddress());
 
+                // If we are configured to use TCP as a fallback also bind a TCP socket
                 builder.socketChannelType(NioSocketChannel.class);
+            } else {
+                dnsServer2.start();
             }
+            builder.queryTimeoutMillis(10000)
+                    .resolvedAddressTypes(ResolvedAddressTypes.IPV4_PREFERRED)
+                    .maxQueriesPerResolve(16)
+                    .nameServerProvider(new SingletonDnsServerAddressStreamProvider(dnsServer2.localAddress()));
             resolver = builder.build();
             if (truncatedBecauseOfMtu) {
                 resolver.ch.pipeline().addFirst(new ChannelInboundHandlerAdapter() {
diff --git a/resolver-dns/src/test/java/io/netty/resolver/dns/TestDnsServer.java b/resolver-dns/src/test/java/io/netty/resolver/dns/TestDnsServer.java
index d7b75e585f03..0db646a2289d 100644
--- a/resolver-dns/src/test/java/io/netty/resolver/dns/TestDnsServer.java
+++ b/resolver-dns/src/test/java/io/netty/resolver/dns/TestDnsServer.java
@@ -92,7 +92,10 @@ public void start() throws IOException {
      * Start the {@link TestDnsServer} but drop all {@code AAAA} queries and not send any response to these at all.
      */
     public void start(final boolean dropAAAAQueries) throws IOException {
-        InetSocketAddress address = new InetSocketAddress(NetUtil.LOCALHOST4, 0);
+        start(dropAAAAQueries, new InetSocketAddress(NetUtil.LOCALHOST4, 0));
+    }
+
+    public void start(final boolean dropAAAAQueries, InetSocketAddress address) throws IOException {
         UdpTransport transport = new UdpTransport(address.getHostName(), address.getPort());
         setTransports(transport);