package com.netflix.hystrix.dashboard.stream; import org.apache.http.Header; import org.apache.http.HttpResponse; import org.apache.http.HttpStatus; import org.apache.http.client.HttpClient; import org.apache.http.client.methods.HttpGet; import org.apache.http.impl.client.DefaultHttpClient; import org.apache.http.impl.conn.PoolingClientConnectionManager; import org.apache.http.params.HttpConnectionParams; import org.apache.http.params.HttpParams; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.util.Map; /** * Proxy an EventStream request (data.stream via proxy.stream) since EventStream does not yet support CORS (https://bugs.webkit.org/show_bug.cgi?id=61862) * so that a UI can request a stream from a different server. */ public class ProxyStreamServlet extends HttpServlet { private static final long serialVersionUID = 1L; private static final Logger logger = LoggerFactory.getLogger(ProxyStreamServlet.class); public ProxyStreamServlet() { super(); } /** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */ @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String origin = request.getParameter("origin"); if (origin == null) { response.setStatus(500); response.getWriter().println("Required parameter 'origin' missing. Example: 107.20.175.135:7001"); } origin = origin.trim(); HttpGet httpget = null; InputStream is = null; boolean hasFirstParameter = false; StringBuilder url = new StringBuilder(); if (!origin.startsWith("http")) { url.append("http://"); } url.append(origin); if (origin.contains("?")) { hasFirstParameter = true; } @SuppressWarnings("unchecked") Map<String, String[]> params = request.getParameterMap(); for (String key : params.keySet()) { if (!key.equals("origin")) { String[] values = params.get(key); String value = values[0].trim(); if (hasFirstParameter) { url.append("&"); } else { url.append("?"); hasFirstParameter = true; } url.append(key).append("=").append(value); } } String proxyUrl = url.toString(); logger.info("\n\nProxy opening connection to: " + proxyUrl + "\n\n"); try { httpget = new HttpGet(proxyUrl); HttpClient client = ProxyConnectionManager.httpClient; HttpResponse httpResponse = client.execute(httpget); int statusCode = httpResponse.getStatusLine().getStatusCode(); if (statusCode == HttpStatus.SC_OK) { // writeTo swallows exceptions and never quits even if outputstream is throwing IOExceptions (such as broken pipe) ... since the inputstream is infinite // httpResponse.getEntity().writeTo(new OutputStreamWrapper(response.getOutputStream())); // so I copy it manually ... is = httpResponse.getEntity().getContent(); // set headers for (Header header : httpResponse.getAllHeaders()) { response.addHeader(header.getName(), header.getValue()); } // copy data from source to response OutputStream os = response.getOutputStream(); int b = -1; while ((b = is.read()) != -1) { try { os.write(b); if (b == 10 /** flush buffer on line feed */) { os.flush(); } } catch (Exception e) { if (e.getClass().getSimpleName().equalsIgnoreCase("ClientAbortException")) { // don't throw an exception as this means the user closed the connection logger.debug("Connection closed by client. Will stop proxying ..."); // break out of the while loop break; } else { // received unknown error while writing so throw an exception throw new RuntimeException(e); } } } } } catch (Exception e) { logger.error("Error proxying request: " + url, e); } finally { if (httpget != null) { try { httpget.abort(); } catch (Exception e) { logger.error("failed aborting proxy connection.", e); } } // httpget.abort() MUST be called first otherwise is.close() hangs (because data is still streaming?) if (is != null) { // this should already be closed by httpget.abort() above try { is.close(); } catch (Exception e) { // e.printStackTrace(); } } } } private static class ProxyConnectionManager { private final static PoolingClientConnectionManager threadSafeConnectionManager = new PoolingClientConnectionManager(); private final static HttpClient httpClient = new DefaultHttpClient(threadSafeConnectionManager); static { logger.debug("Initialize ProxyConnectionManager"); /* common settings */ HttpParams httpParams = httpClient.getParams(); HttpConnectionParams.setConnectionTimeout(httpParams, 5000); HttpConnectionParams.setSoTimeout(httpParams, 10000); /* number of connections to allow */ threadSafeConnectionManager.setDefaultMaxPerRoute(400); threadSafeConnectionManager.setMaxTotal(400); } } }