org.apache.hadoop.hdfs.server.namenode.DfsServlet.java Source code

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Here is the source code for org.apache.hadoop.hdfs.server.namenode.DfsServlet.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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 org.apache.hadoop.hdfs.server.namenode;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.URI;
import java.net.URISyntaxException;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hdfs.DFSClient;
import org.apache.hadoop.hdfs.protocol.ClientProtocol;
import org.apache.hadoop.hdfs.protocol.DatanodeID;
import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
import org.apache.hadoop.ipc.RemoteException;
import org.apache.hadoop.security.UserGroupInformation;
import org.znerd.xmlenc.XMLOutputter;

/**
 * A base class for the servlets in DFS.
 */
abstract class DfsServlet extends HttpServlet {
    /** For java.io.Serializable */
    private static final long serialVersionUID = 1L;

    static final Log LOG = LogFactory.getLog(DfsServlet.class.getCanonicalName());

    /** Write the object to XML format */
    protected void writeXml(Exception except, String path, XMLOutputter doc) throws IOException {
        doc.startTag(RemoteException.class.getSimpleName());
        doc.attribute("path", path);
        if (except instanceof RemoteException) {
            doc.attribute("class", ((RemoteException) except).getClassName());
        } else {
            doc.attribute("class", except.getClass().getName());
        }
        String msg = except.getLocalizedMessage();
        int i = msg.indexOf("\n");
        if (i >= 0) {
            msg = msg.substring(0, i);
        }
        doc.attribute("message", msg.substring(msg.indexOf(":") + 1).trim());
        doc.endTag();
    }

    /** Get {@link UserGroupInformation} from request 
     *    * @throws IOException */
    protected UserGroupInformation getUGI(HttpServletRequest request, Configuration conf) throws IOException {
        return JspHelper.getUGI(getServletContext(), request, conf);
    }

    /**
     * Create a {@link NameNode} proxy from the current {@link ServletContext}. 
     */
    protected ClientProtocol createNameNodeProxy() throws IOException {
        ServletContext context = getServletContext();
        // if we are running in the Name Node, use it directly rather than via 
        // rpc
        NameNode nn = (NameNode) context.getAttribute("name.node");
        if (nn != null) {
            return nn;
        }
        InetSocketAddress nnAddr = (InetSocketAddress) context.getAttribute("name.node.address");
        Configuration conf = new Configuration((Configuration) context.getAttribute(JspHelper.CURRENT_CONF));
        return DFSClient.createNamenode(nnAddr, conf);
    }

    /** Create a URI for redirecting request */
    protected URI createRedirectUri(String servletpath, UserGroupInformation ugi, DatanodeID host,
            HttpServletRequest request, String tokenString) throws URISyntaxException {
        final String hostname = host instanceof DatanodeInfo ? ((DatanodeInfo) host).getHostName() : host.getHost();
        final String scheme = request.getScheme();
        final int port = "https".equals(scheme) ? (Integer) getServletContext().getAttribute("datanode.https.port")
                : host.getInfoPort();
        final String filename = request.getPathInfo();
        String dt = "";
        if (tokenString != null) {
            dt = JspHelper.getDelegationTokenUrlParam(tokenString);
        }
        return new URI(scheme, null, hostname, port, servletpath,
                "filename=" + filename + "&ugi=" + ugi.getShortUserName() + dt, null);
    }

    /** Get filename from the request */
    protected String getFilename(HttpServletRequest request, HttpServletResponse response) throws IOException {
        final String filename = request.getParameter("filename");
        if (filename == null || filename.length() == 0) {
            throw new IOException("Invalid filename");
        }
        return filename;
    }
}