Use Jetty's ProxyServlet implementation

bundles/ui/org.eclipse.smarthome.ui/META-INF/MANIFEST.MF

@@ -18,6 +18,7 @@ Import-Package: javax.imageio,
  org.eclipse.jetty.client.api,
  org.eclipse.jetty.client.util,
  org.eclipse.jetty.http,
+ org.eclipse.jetty.proxy;resolution:=optional,
  org.eclipse.jetty.util,
  org.eclipse.jetty.util.component,
  org.eclipse.jetty.util.ssl,

bundles/ui/org.eclipse.smarthome.ui/OSGI-INF/proxy.xml

@@ -9,7 +9,10 @@
 
 -->
 <scr:component xmlns:scr="http://www.osgi.org/xmlns/scr/v1.1.0" activate="activate" deactivate="deactivate" immediate="true" name="org.eclipse.smarthome.ui.proxy">
-   <implementation class="org.eclipse.smarthome.ui.internal.proxy.ProxyServlet"/>
+   <implementation class="org.eclipse.smarthome.ui.internal.proxy.ProxyServletService"/>
+
+   <property name="service.pid" type="String" value="org.eclipse.smarthome.proxy"/>
+
    <reference bind="setItemUIRegistry" cardinality="1..1" interface="org.eclipse.smarthome.ui.items.ItemUIRegistry" name="ItemUIRegistry" policy="dynamic" unbind="unsetItemUIRegistry"/>
    <reference bind="setHttpService" cardinality="1..1" interface="org.osgi.service.http.HttpService" name="HttpService" policy="dynamic" unbind="unsetHttpService"/>
    <reference bind="setModelRepository" cardinality="1..1" interface="org.eclipse.smarthome.model.core.ModelRepository" name="ModelRepository" policy="static" unbind="unsetModelRepository"/>

bundles/ui/org.eclipse.smarthome.ui/src/main/java/org/eclipse/smarthome/ui/internal/proxy/AsyncProxyServlet.java

@@ -0,0 +1,81 @@
+/**
+ * Copyright (c) 2014-2016 by the respective copyright holders.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ */
+package org.eclipse.smarthome.ui.internal.proxy;
+
+import java.util.Objects;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import org.eclipse.jetty.client.HttpClient;
+import org.eclipse.jetty.client.api.Request;
+import org.eclipse.jetty.util.ssl.SslContextFactory;
+
+/**
+ * This version of the proxy servlet uses asynchronous I/O and request processing, and is based on Jetty's proxy
+ * servlets. It depends on Servlet API 3.0 or later.
+ *
+ * @author John Cocula - new version that uses Jetty proxy classes
+ */
+public class AsyncProxyServlet extends org.eclipse.jetty.proxy.AsyncProxyServlet {
+
+    private static final long serialVersionUID = -4716754591953017795L;
+
+    private final ProxyServletService service;
+
+    AsyncProxyServlet(ProxyServletService service) {
+        super();
+        this.service = service;
+    }
+
+    @Override
+    public String getServletInfo() {
+        return "Proxy (async)";
+    }
+
+    /**
+     * {@inheritDoc}
+     *
+     * Override <code>newHttpClient</code> so we can proxy to HTTPS URIs.
+     */
+    @Override
+    protected HttpClient newHttpClient() {
+        return new HttpClient(new SslContextFactory());
+    }
+
+    /**
+     * {@inheritDoc}
+     *
+     * Add Basic Authentication header to request if user and password are specified in URI.
+     *
+     * After Jetty is upgraded past 9.2.9, change to <code>copyRequestHeaders</code> to avoid deprecation warning.
+     */
+    @SuppressWarnings("deprecation")
+    @Override
+    protected void copyHeaders(HttpServletRequest clientRequest, Request proxyRequest) {
+        super.copyHeaders(clientRequest, proxyRequest);
+
+        service.maybeAppendAuthHeader(service.uriFromRequest(clientRequest), proxyRequest);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    protected String rewriteTarget(HttpServletRequest request) {
+        return Objects.toString(service.uriFromRequest(request), null);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    protected void onProxyRewriteFailed(HttpServletRequest request, HttpServletResponse response) {
+        service.sendError(request, response);
+    }
+}

bundles/ui/org.eclipse.smarthome.ui/src/main/java/org/eclipse/smarthome/ui/internal/proxy/BlockingProxyServlet.java

@@ -0,0 +1,116 @@
+/**
+ * Copyright (c) 2014-2016 by the respective copyright holders.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ */
+package org.eclipse.smarthome.ui.internal.proxy;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.URI;
+import java.util.Iterator;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import org.apache.commons.io.IOUtils;
+import org.eclipse.jetty.client.HttpClient;
+import org.eclipse.jetty.client.api.Request;
+import org.eclipse.jetty.client.api.Response;
+import org.eclipse.jetty.client.util.InputStreamResponseListener;
+import org.eclipse.jetty.http.HttpField;
+import org.eclipse.jetty.http.HttpFields;
+import org.eclipse.jetty.util.ssl.SslContextFactory;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * A blocking version of the proxy servlet that complies with Servlet API 2.4.
+ *
+ * @author Kai Kreuzer - Initial contribution and API
+ * @author Svilen Valkanov - Replaced Apache HttpClient with Jetty
+ * @author John Cocula - refactored to support alternate implementation
+ */
+public class BlockingProxyServlet extends HttpServlet {
+
+    private final Logger logger = LoggerFactory.getLogger(BlockingProxyServlet.class);
+
+    private static final long serialVersionUID = -4716754591953017794L;
+
+    private final ProxyServletService service;
+
+    private static HttpClient httpClient = new HttpClient(new SslContextFactory());
+
+    /** Timeout for HTTP requests in ms */
+    private static final int TIMEOUT = 15000;
+
+    BlockingProxyServlet(ProxyServletService service) {
+        super();
+        this.service = service;
+        if (!httpClient.isStarted()) {
+            try {
+                httpClient.start();
+            } catch (Exception e) {
+                logger.warn("Cannot start HttpClient!", e);
+            }
+        }
+    }
+
+    @Override
+    public String getServletInfo() {
+        return "Proxy (blocking)";
+    }
+
+    @Override
+    protected void doGet(HttpServletRequest request, HttpServletResponse response)
+            throws ServletException, IOException {
+
+        URI uri = service.uriFromRequest(request);
+
+        if (uri == null) {
+            service.sendError(request, response);
+        } else {
+            Request httpRequest = httpClient.newRequest(uri);
+
+            service.maybeAppendAuthHeader(uri, httpRequest);
+
+            InputStreamResponseListener listener = new InputStreamResponseListener();
+
+            // do the client request
+            try {
+                httpRequest.send(listener);
+                // wait for the response headers to arrive or the timeout to expire
+                Response httpResponse = listener.get(TIMEOUT, TimeUnit.MILLISECONDS);
+
+                // get response headers
+                HttpFields headers = httpResponse.getHeaders();
+                Iterator<HttpField> iterator = headers.iterator();
+
+                // copy all headers
+                while (iterator.hasNext()) {
+                    HttpField header = iterator.next();
+                    response.setHeader(header.getName(), header.getValue());
+                }
+            } catch (Exception e) {
+                if (e instanceof TimeoutException) {
+                    logger.warn("Proxy servlet failed to stream content due to a timeout");
+                    response.sendError(HttpServletResponse.SC_GATEWAY_TIMEOUT);
+                } else {
+                    logger.warn("Proxy servlet failed to stream content: {}", e.getMessage());
+                    response.sendError(HttpServletResponse.SC_BAD_REQUEST, e.getMessage());
+                }
+                return;
+            }
+            // now copy/stream the body content
+            try (InputStream responseContent = listener.getInputStream()) {
+                IOUtils.copy(responseContent, response.getOutputStream());
+            }
+        }
+    }
+}