Fixes #5888 - Limit usage of HTTP/2 connections. (#12401)

* Made the high-level HttpConnectionOverHTTP2 implement MaxUsable, so it cannot be used to open more streams than allowed.
* Introduced HTTP2Session.maxTotalLocalStreams to limit the max number of streams that might be created in a connection. Linked this new property with the high-level AbstractConnectionPool.maxUsage.
* Implemented low-level handling of explicit stream ids provided by applications.
* Implemented low-level handling of stream id overflow.
* Added test cases.

Signed-off-by: Simone Bordet <simone.bordet@gmail.com>
Signed-off-by: Ludovic Orban <lorban@bitronix.be>
Co-authored-by: Ludovic Orban <lorban@bitronix.be>

jetty-core/jetty-client/src/main/java/org/eclipse/jetty/client/AbstractConnectionPool.java

@@ -341,7 +341,7 @@ protected Connection activate()
 
                 int maxUsage = getMaxUsage();
                 if (connection instanceof MaxUsable maxUsable)
-                    maxUsage = maxUsable.getMaxUsage();
+                    maxUsage = Math.min(maxUsage, maxUsable.getMaxUsage());
                 if (maxUsage > 0)
                 {
                     EntryHolder holder = (EntryHolder)((Attachable)connection).getAttachment();

jetty-core/jetty-http2/jetty-http2-client-transport/src/main/java/org/eclipse/jetty/http2/client/transport/internal/HTTPSessionListenerPromise.java

@@ -18,7 +18,9 @@
 import java.util.concurrent.TimeoutException;
 import java.util.concurrent.atomic.AtomicMarkableReference;
 
+import org.eclipse.jetty.client.AbstractConnectionPool;
 import org.eclipse.jetty.client.Connection;
+import org.eclipse.jetty.client.ConnectionPool;
 import org.eclipse.jetty.client.Destination;
 import org.eclipse.jetty.client.HttpClientTransport;
 import org.eclipse.jetty.http2.HTTP2Connection;
@@ -73,10 +75,15 @@ public void onSettings(Session session, SettingsFrame frame)
 
     private void onServerPreface(Session session)
     {
+        Destination destination = destination();
         HTTP2Connection http2Connection = (HTTP2Connection)context.get(HTTP2Connection.class.getName());
-        HttpConnectionOverHTTP2 connection = (HttpConnectionOverHTTP2)newConnection(destination(), session, http2Connection);
+        HttpConnectionOverHTTP2 connection = (HttpConnectionOverHTTP2)newConnection(destination, session, http2Connection);
         if (this.connection.compareAndSet(null, connection, false, true))
         {
+            ConnectionPool connectionPool = destination.getConnectionPool();
+            if (connectionPool instanceof AbstractConnectionPool pool)
+                connection.setMaxUsage(pool.getMaxUsage());
+
             // The connection promise must be called synchronously
             // so that the HTTP/1 to HTTP/2 upgrade can create the
             // HTTP/2 stream that represents the HTTP/1 request.

jetty-core/jetty-http2/jetty-http2-client-transport/src/main/java/org/eclipse/jetty/http2/client/transport/internal/HttpConnectionOverHTTP2.java

@@ -50,7 +50,7 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-public class HttpConnectionOverHTTP2 extends HttpConnection implements Sweeper.Sweepable, ConnectionPool.MaxMultiplexable
+public class HttpConnectionOverHTTP2 extends HttpConnection implements Sweeper.Sweepable, ConnectionPool.MaxMultiplexable, ConnectionPool.MaxUsable
 {
     private static final Logger LOG = LoggerFactory.getLogger(HttpConnectionOverHTTP2.class);
 
@@ -108,6 +108,17 @@ public int getMaxMultiplex()
         return ((HTTP2Session)session).getMaxLocalStreams();
     }
 
+    @Override
+    public int getMaxUsage()
+    {
+        return ((HTTP2Session)session).getMaxTotalLocalStreams();
+    }
+
+    void setMaxUsage(int maxUsage)
+    {
+        ((HTTP2Session)session).setMaxTotalLocalStreams(maxUsage);
+    }
+
     @Override
     protected Iterator<HttpChannel> getHttpChannels()
     {