Allow to wrap another SslContext implementation and do extra init steps on the SSLEngine.

Motivation:

Sometimes its needed to customize the SSLEngine (like setting protocols etc). For this it would be useful if the user could wrap an SslContext and do init steps on the SSLEngine.

Modifications:

Add new SslContext implementation which can wrap another one and allow to customize the SSLEngine

Result:

More flexible usage of SslContext.

handler/src/main/java/io/netty/handler/ssl/DelegatingSslContext.java

@@ -0,0 +1,84 @@
+/*
+ * Copyright 2016 The Netty Project
+ *
+ * The Netty Project licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+package io.netty.handler.ssl;
+
+import io.netty.buffer.ByteBufAllocator;
+import io.netty.util.internal.ObjectUtil;
+
+import javax.net.ssl.SSLEngine;
+import javax.net.ssl.SSLSessionContext;
+import java.util.List;
+
+/**
+ * Adapter class which allows to wrap another {@link SslContext} and init {@link SSLEngine} instances.
+ */
+public abstract class DelegatingSslContext extends SslContext {
+
+    private final SslContext ctx;
+
+    protected DelegatingSslContext(SslContext ctx) {
+        this.ctx = ObjectUtil.checkNotNull(ctx, "ctx");
+    }
+
+    @Override
+    public final boolean isClient() {
+        return ctx.isClient();
+    }
+
+    @Override
+    public final List<String> cipherSuites() {
+        return ctx.cipherSuites();
+    }
+
+    @Override
+    public final long sessionCacheSize() {
+        return ctx.sessionCacheSize();
+    }
+
+    @Override
+    public final long sessionTimeout() {
+        return ctx.sessionTimeout();
+    }
+
+    @Override
+    public final ApplicationProtocolNegotiator applicationProtocolNegotiator() {
+        return ctx.applicationProtocolNegotiator();
+    }
+
+    @Override
+    public final SSLEngine newEngine(ByteBufAllocator alloc) {
+        SSLEngine engine = ctx.newEngine(alloc);
+        initEngine(engine);
+        return engine;
+    }
+
+    @Override
+    public final SSLEngine newEngine(ByteBufAllocator alloc, String peerHost, int peerPort) {
+        SSLEngine engine = ctx.newEngine(alloc, peerHost, peerPort);
+        initEngine(engine);
+        return engine;
+    }
+
+    @Override
+    public final SSLSessionContext sessionContext() {
+        return ctx.sessionContext();
+    }
+
+    /**
+     * Init the {@link SSLEngine}.
+     */
+    protected abstract void initEngine(SSLEngine engine);
+}