/**
* 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.URI;
import java.net.URISyntaxException;
import java.security.PrivilegedExceptionAction;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.Path;
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.hdfs.protocol.HdfsFileStatus;
import org.apache.hadoop.hdfs.protocol.LocatedBlocks;
import org.apache.hadoop.security.UserGroupInformation;
/** Redirect queries about the hosted filesystem to an appropriate datanode.
* @see org.apache.hadoop.hdfs.HftpFileSystem
*/
public class FileDataServlet extends DfsServlet {
/** Create a redirection URI */
protected URI createUri(String parent, HdfsFileStatus i, UserGroupInformation ugi,
ClientProtocol nnproxy, HttpServletRequest request, String dt)
throws IOException, URISyntaxException {
String scheme = request.getScheme();
final DatanodeID host = pickSrcDatanode(parent, i, nnproxy);
final String hostname;
if (host instanceof DatanodeInfo) {
hostname = ((DatanodeInfo)host).getHostName();
} else {
hostname = host.getHost();
}
String dtParam="";
if (dt != null) {
StringBuilder sb = new StringBuilder(JspHelper.SET_DELEGATION).append(dt);
dtParam=sb.toString();
}
return new URI(scheme, null, hostname,
"https".equals(scheme)
? (Integer)getServletContext().getAttribute("datanode.https.port")
: host.getInfoPort(),
"/streamFile", "filename=" + i.getFullName(parent) +
"&ugi=" + ugi.getShortUserName() + dtParam, null);
}
private static JspHelper jspHelper = null;
/** Select a datanode to service this request.
* Currently, this looks at no more than the first five blocks of a file,
* selecting a datanode randomly from the most represented.
*/
private static DatanodeID pickSrcDatanode(String parent, HdfsFileStatus i,
ClientProtocol nnproxy) throws IOException {
// a race condition can happen by initializing a static member this way.
// A proper fix should make JspHelper a singleton. Since it doesn't affect
// correctness, we leave it as is for now.
if (jspHelper == null)
jspHelper = new JspHelper();
final LocatedBlocks blks = nnproxy.getBlockLocations(
i.getFullPath(new Path(parent)).toUri().getPath(), 0, 1);
if (i.getLen() == 0 || blks.getLocatedBlocks().size() <= 0) {
// pick a random datanode
return jspHelper.randomNode();
}
return jspHelper.bestNode(blks.get(0));
}
/**
* Service a GET request as described below.
* Request:
* {@code
* GET http://<nn>:<port>/data[/<path>] HTTP/1.1
* }
*/
public void doGet(final HttpServletRequest request,
final HttpServletResponse response)
throws IOException {
Configuration conf =
(Configuration) getServletContext().getAttribute(JspHelper.CURRENT_CONF);
final UserGroupInformation ugi = getUGI(request, conf);
try {
ugi.doAs(new PrivilegedExceptionAction<Void>() {
@Override
public Void run() throws IOException {
ClientProtocol nn = createNameNodeProxy();
final String path =
request.getPathInfo() != null ? request.getPathInfo() : "/";
String delegationToken =
request.getParameter(JspHelper.DELEGATION_PARAMETER_NAME);
HdfsFileStatus info = nn.getFileInfo(path);
if ((info != null) && !info.isDir()) {
try {
response.sendRedirect(createUri(path, info, ugi, nn,
request, delegationToken).toURL().toString());
} catch (URISyntaxException e) {
response.getWriter().println(e.toString());
}
} else if (info == null){
response.sendError(400, "cat: File not found " + path);
} else {
response.sendError(400, "cat: " + path + ": is a directory");
}
return null;
}
});
} catch (IOException e) {
response.sendError(400, e.getMessage());
} catch (InterruptedException e) {
response.sendError(400, e.getMessage());
}
}
}