Issue #14061 - Fix Alt-Svc header to use HTTP/3 connector port

documentation/jetty/modules/code/examples/src/main/java/org/eclipse/jetty/docs/programming/server/http/HTTPServerDocs.java

@@ -614,6 +614,25 @@ public void h3() throws Exception
         // end::h3[]
     }
 
+    public void h2altsvc()
+    {
+        // tag::h2altsvc[]
+        HttpConfiguration httpConfig = new HttpConfiguration();
+        HTTP2ServerConnectionFactory h2 = new HTTP2ServerConnectionFactory(httpConfig);
+
+        // Configure AltSvcCustomizer after connection factory creation.
+        httpConfig.getCustomizers().stream()
+            .filter(c -> c instanceof HTTP2ServerConnectionFactory.AltSvcCustomizer)
+            .map(HTTP2ServerConnectionFactory.AltSvcCustomizer.class::cast)
+            .findFirst()
+            .ifPresent(customizer ->
+            {
+                customizer.setMaxAge(Duration.ofHours(24));
+                customizer.setPersist(true);
+            });
+        // end::h2altsvc[]
+    }
+
     public void conscrypt()
     {
         // tag::conscrypt[]

documentation/jetty/modules/programming-guide/pages/server/http.adoc

@@ -533,10 +533,22 @@ Alt-Svc: h3=":843"
 ----
 
 The presence of this header indicates that protocol `h3` is available on the same host (since no host is defined before the port), but on port `843` (although it may be the same port `443`).
+The `ma` (max-age) attribute specifies how long (in seconds) the client should cache this information (86400 seconds = 24 hours).
 The HTTP/3 client may now initiate a QUIC connection on port `843` and make HTTP/3 requests.
 
 NOTE: It is nowadays common to use the same port `443` for both HTTP/2 and HTTP/3. This does not cause problems because HTTP/2 listens on the TCP port `443`, while QUIC listens on the UDP port `443`.
 
+TIP: The `Alt-Svc` header is automatically added to HTTP/2 responses by `HTTP2ServerConnectionFactory.AltSvcCustomizer`, advertising the HTTP/3 connector's port.
+By default, only the port is advertised without additional attributes.
+The `ma` (max-age) attribute can be configured via `AltSvcCustomizer.setMaxAge(Duration)` and the `persist` attribute via `AltSvcCustomizer.setPersist(boolean)`.
+
+To configure the `AltSvcCustomizer`, retrieve it from the `HttpConfiguration` after creating the `HTTP2ServerConnectionFactory`:
+
+[,java,indent=0,options=nowrap]
+----
+include::code:example$src/main/java/org/eclipse/jetty/docs/programming/server/http/HTTPServerDocs.java[tags=h2altsvc]
+----
+
 It is therefore common for HTTP/3 clients to initiate connections using the HTTP/2 protocol over TCP, and if the server supports HTTP/3 switch to HTTP/3 as indicated by the server.
 
 [plantuml]

jetty-core/jetty-http2/jetty-http2-server/src/main/java/org/eclipse/jetty/http2/server/HTTP2ServerConnectionFactory.java

@@ -14,9 +14,13 @@
 package org.eclipse.jetty.http2.server;
 
 import java.io.EOFException;
+import java.time.Duration;
 import java.util.Map;
 import java.util.concurrent.TimeoutException;
 
+import org.eclipse.jetty.http.HttpFields;
+import org.eclipse.jetty.http.HttpHeader;
+import org.eclipse.jetty.http.HttpVersion;
 import org.eclipse.jetty.http2.ErrorCode;
 import org.eclipse.jetty.http2.HTTP2Cipher;
 import org.eclipse.jetty.http2.HTTP2Stream;
@@ -35,6 +39,9 @@
 import org.eclipse.jetty.server.Connector;
 import org.eclipse.jetty.server.HttpConfiguration;
 import org.eclipse.jetty.server.NegotiatingServerConnection.CipherDiscriminator;
+import org.eclipse.jetty.server.NetworkConnector;
+import org.eclipse.jetty.server.Request;
+import org.eclipse.jetty.server.Server;
 import org.eclipse.jetty.util.Callback;
 import org.eclipse.jetty.util.Promise;
 import org.eclipse.jetty.util.StringUtil;
@@ -54,11 +61,13 @@ public HTTP2ServerConnectionFactory()
     public HTTP2ServerConnectionFactory(@Name("config") HttpConfiguration httpConfiguration)
     {
         super(httpConfiguration);
+        httpConfiguration.addCustomizer(new AltSvcCustomizer());
     }
 
     public HTTP2ServerConnectionFactory(@Name("config") HttpConfiguration httpConfiguration, @Name("protocols") String... protocols)
     {
         super(httpConfiguration, protocols);
+        httpConfiguration.addCustomizer(new AltSvcCustomizer());
     }
 
     @Override
@@ -191,4 +200,83 @@ private void close(Stream stream, String reason)
             stream.getSession().close(ErrorCode.PROTOCOL_ERROR.code, reason, Callback.NOOP);
         }
     }
+
+    /**
+     * <p>An {@link HttpConfiguration.Customizer} that adds the {@code Alt-Svc}
+     * header to HTTP/2 responses, advertising HTTP/3 support if an HTTP/3
+     * connector is available on the server.</p>
+     */
+    public static class AltSvcCustomizer implements HttpConfiguration.Customizer
+    {
+        private Duration _maxAge;
+        private boolean _persist;
+
+        /**
+         * @return The max age for the Alt-Svc response header, or null if no max-age attribute should be sent.
+         */
+        public Duration getMaxAge()
+        {
+            return _maxAge;
+        }
+
+        /**
+         * Sets the Alt-Svc max age.
+         *
+         * @param maxAge the max age for the Alt-Svc response header, or null if no max-age attribute should be sent.
+         */
+        public void setMaxAge(Duration maxAge)
+        {
+            _maxAge = maxAge;
+        }
+
+        /**
+         * @return whether the persist parameter should be included in the Alt-Svc header.
+         */
+        public boolean isPersist()
+        {
+            return _persist;
+        }
+
+        /**
+         * Sets whether to include the persist parameter in the Alt-Svc header.
+         * When true, adds {@code persist=1} to indicate the alternative service
+         * should be persisted across network changes.
+         *
+         * @param persist true to include the persist parameter, false otherwise.
+         * @see <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Alt-Svc#persist1">Alt-Svc persist parameter</a>
+         */
+        public void setPersist(boolean persist)
+        {
+            _persist = persist;
+        }
+
+        @Override
+        public Request customize(Request request, HttpFields.Mutable responseHeaders)
+        {
+            if (HttpVersion.HTTP_2 != request.getConnectionMetaData().getHttpVersion())
+                return request;
+
+            Server server = request.getConnectionMetaData().getConnector().getServer();
+            for (Connector connector : server.getConnectors())
+            {
+                if (connector instanceof NetworkConnector nc &&
+                    connector.getProtocols().contains("h3"))
+                {
+                    int port = nc.getLocalPort();
+                    if (port > 0)
+                    {
+                        StringBuilder altSvc = new StringBuilder();
+                        altSvc.append(String.format("h3=\":%d\"", port));
+                        if (_maxAge != null)
+                            altSvc.append(String.format("; ma=%d", _maxAge.toSeconds()));
+                        if (_persist)
+                            altSvc.append("; persist=1");
+                        responseHeaders.add(HttpHeader.ALT_SVC, altSvc.toString());
+                    }
+                    break;
+                }
+            }
+            return request;
+        }
+    }
 }

jetty-core/jetty-http3/jetty-http3-server/src/main/java/org/eclipse/jetty/http3/server/HTTP3ServerConnectionFactory.java

@@ -17,9 +17,6 @@
 import java.util.concurrent.Executor;
 import java.util.concurrent.TimeoutException;
 
-import org.eclipse.jetty.http.HttpFields;
-import org.eclipse.jetty.http.HttpHeader;
-import org.eclipse.jetty.http.HttpVersion;
 import org.eclipse.jetty.http3.HTTP3Stream;
 import org.eclipse.jetty.http3.api.Session;
 import org.eclipse.jetty.http3.api.Stream;
@@ -28,11 +25,7 @@
 import org.eclipse.jetty.http3.server.internal.HTTP3StreamServer;
 import org.eclipse.jetty.http3.server.internal.HttpStreamOverHTTP3;
 import org.eclipse.jetty.http3.server.internal.ServerHTTP3StreamConnection;
-import org.eclipse.jetty.server.ConnectionMetaData;
-import org.eclipse.jetty.server.Connector;
 import org.eclipse.jetty.server.HttpConfiguration;
-import org.eclipse.jetty.server.NetworkConnector;
-import org.eclipse.jetty.server.Request;
 import org.eclipse.jetty.util.Promise;
 import org.eclipse.jetty.util.thread.Invocable;
 import org.eclipse.jetty.util.thread.ThreadPool;
@@ -49,20 +42,6 @@ public HTTP3ServerConnectionFactory()
     public HTTP3ServerConnectionFactory(HttpConfiguration configuration)
     {
         super(configuration, new HTTP3SessionListener());
-        configuration.addCustomizer(new AltSvcCustomizer());
-    }
-
-    private static class AltSvcCustomizer implements HttpConfiguration.Customizer
-    {
-        @Override
-        public Request customize(Request request, HttpFields.Mutable responseHeaders)
-        {
-            ConnectionMetaData connectionMetaData = request.getConnectionMetaData();
-            Connector connector = connectionMetaData.getConnector();
-            if (connector instanceof NetworkConnector networkConnector && HttpVersion.HTTP_2 == connectionMetaData.getHttpVersion())
-                responseHeaders.add(HttpHeader.ALT_SVC, String.format("h3=\":%d\"", networkConnector.getLocalPort()));
-            return request;
-        }
     }
 
     private static class HTTP3SessionListener implements HTTP3SessionServer.Listener