HDFS-2652. Add support for host-based delegation tokens. Contributed by Daryn Sharp

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1327309 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -860,6 +860,9 @@ Release 0.23.3 - UNRELEASED
     HDFS-3176. Use MD5MD5CRC32FileChecksum.readFields() in JsonUtil .  (Kihwal
     Lee via szetszwo)
 
+    HDFS-2652. Add support for host-based delegation tokens.  (Daryn Sharp via
+    szetszwo)
+
 Release 0.23.2 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/HAUtil.java

@@ -52,6 +52,9 @@ public class HAUtil {
   private static final Log LOG = 
     LogFactory.getLog(HAUtil.class);
   
+  private static final DelegationTokenSelector tokenSelector =
+      new DelegationTokenSelector();
+
   private HAUtil() { /* Hidden constructor */ }
 
   /**
@@ -241,25 +244,28 @@ public static boolean isTokenForLogicalUri(
    * one is found, clone it to also represent the underlying namenode address.
    * @param ugi the UGI to modify
    * @param haUri the logical URI for the cluster
-   * @param singleNNAddr one of the NNs in the cluster to which the token
+   * @param nnAddrs collection of NNs in the cluster to which the token
    * applies
    */
   public static void cloneDelegationTokenForLogicalUri(
       UserGroupInformation ugi, URI haUri,
-      InetSocketAddress singleNNAddr) {
+      Collection<InetSocketAddress> nnAddrs) {
-    Text haService = buildTokenServiceForLogicalUri(haUri);
+    Text haService = HAUtil.buildTokenServiceForLogicalUri(haUri);
     Token<DelegationTokenIdentifier> haToken =
-        DelegationTokenSelector.selectHdfsDelegationToken(haService, ugi);
+        tokenSelector.selectToken(haService, ugi.getTokens());
-    if (haToken == null) {
+    if (haToken != null) {
-      // no token
+      for (InetSocketAddress singleNNAddr : nnAddrs) {
-      return;
+        Token<DelegationTokenIdentifier> specificToken =
+            new Token<DelegationTokenIdentifier>(haToken);
+        SecurityUtil.setTokenService(specificToken, singleNNAddr);
+        ugi.addToken(specificToken);
+        LOG.debug("Mapped HA service delegation token for logical URI " +
+            haUri + " to namenode " + singleNNAddr);
+      }
+    } else {
+      LOG.debug("No HA service delegation token found for logical URI " +
+          haUri);
     }
-    Token<DelegationTokenIdentifier> specificToken =
-        new Token<DelegationTokenIdentifier>(haToken);
-    specificToken.setService(SecurityUtil.buildTokenService(singleNNAddr));
-    ugi.addToken(specificToken);
-    LOG.debug("Mapped HA service delegation token for logical URI " +
-        haUri + " to namenode " + singleNNAddr);
   }
 
   /**

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/HftpFileSystem.java

@@ -30,6 +30,7 @@
 import java.text.ParseException;
 import java.text.SimpleDateFormat;
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.TimeZone;
 
 import org.apache.hadoop.classification.InterfaceAudience;
@@ -48,7 +49,6 @@
 import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenRenewer;
 import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenSelector;
 import org.apache.hadoop.hdfs.server.common.JspHelper;
-import org.apache.hadoop.hdfs.server.namenode.NameNode;
 import org.apache.hadoop.hdfs.tools.DelegationTokenFetcher;
 import org.apache.hadoop.hdfs.web.URLUtils;
 import org.apache.hadoop.io.Text;
@@ -168,10 +168,7 @@ public void initialize(final URI name, final Configuration conf)
 
   protected void initDelegationToken() throws IOException {
     // look for hftp token, then try hdfs
-    Token<?> token = selectHftpDelegationToken();
+    Token<?> token = selectDelegationToken();
-    if (token == null) {
-      token = selectHdfsDelegationToken();
-    }  
 
     // if we don't already have a token, go get one over https
     boolean createdToken = false;
@@ -192,14 +189,8 @@ protected void initDelegationToken() throws IOException {
     }
   }
 
-  protected Token<DelegationTokenIdentifier> selectHftpDelegationToken() {
+  protected Token<DelegationTokenIdentifier> selectDelegationToken() {
-    Text serviceName = SecurityUtil.buildTokenService(nnSecureAddr);
+  	return hftpTokenSelector.selectToken(getUri(), ugi.getTokens(), getConf());
-    return hftpTokenSelector.selectToken(serviceName, ugi.getTokens());
-  }
-
-  protected Token<DelegationTokenIdentifier> selectHdfsDelegationToken() {
-    return  DelegationTokenSelector.selectHdfsDelegationToken(
-        nnAddr, ugi, getConf());
   }
   
 
@@ -699,9 +690,22 @@ public void cancel(Token<?> token,
   
   private static class HftpDelegationTokenSelector
   extends AbstractDelegationTokenSelector<DelegationTokenIdentifier> {
+    private static final DelegationTokenSelector hdfsTokenSelector =
+        new DelegationTokenSelector();
 
     public HftpDelegationTokenSelector() {
       super(TOKEN_KIND);
     }
+    
+    Token<DelegationTokenIdentifier> selectToken(URI nnUri,
+        Collection<Token<?>> tokens, Configuration conf) {
+      Token<DelegationTokenIdentifier> token =
+          selectToken(SecurityUtil.buildTokenService(nnUri), tokens);
+      if (token == null) {
+        // try to get a HDFS token
+        token = hdfsTokenSelector.selectToken(nnUri, tokens, conf); 
+      }
+      return token;
+    }
   }
 }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/security/token/delegation/DelegationTokenSelector.java

@@ -17,7 +17,8 @@
  */
 package org.apache.hadoop.hdfs.security.token.delegation;
 
-import java.net.InetSocketAddress;
+import java.net.URI;
+import java.util.Collection;
 
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.conf.Configuration;
@@ -25,7 +26,6 @@
 import org.apache.hadoop.io.Text;
 import org.apache.hadoop.net.NetUtils;
 import org.apache.hadoop.security.SecurityUtil;
-import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.security.token.Token;
 import org.apache.hadoop.security.token.delegation.AbstractDelegationTokenSelector;
 
@@ -37,32 +37,35 @@ public class DelegationTokenSelector
     extends AbstractDelegationTokenSelector<DelegationTokenIdentifier>{
   public static final String SERVICE_NAME_KEY = "hdfs.service.host_";
 
-  private static final DelegationTokenSelector INSTANCE = new DelegationTokenSelector();
+  /**
-
+   * Select the delegation token for hdfs.  The port will be rewritten to
-  /** Select the delegation token for hdfs from the ugi. */
+   * the port of hdfs.service.host_$nnAddr, or the default rpc namenode port. 
-  public static Token<DelegationTokenIdentifier> selectHdfsDelegationToken(
+   * This method should only be called by non-hdfs filesystems that do not
-      final InetSocketAddress nnAddr, final UserGroupInformation ugi,
+   * use the rpc port to acquire tokens.  Ex. webhdfs, hftp 
+   * @param nnUri of the remote namenode
+   * @param tokens as a collection
+   * @param conf hadoop configuration
+   * @return Token
+   */
+  public Token<DelegationTokenIdentifier> selectToken(
+      final URI nnUri, Collection<Token<?>> tokens,
       final Configuration conf) {
     // this guesses the remote cluster's rpc service port.
     // the current token design assumes it's the same as the local cluster's
     // rpc port unless a config key is set.  there should be a way to automatic
     // and correctly determine the value
-    final String key = SERVICE_NAME_KEY + SecurityUtil.buildTokenService(nnAddr);
+    Text serviceName = SecurityUtil.buildTokenService(nnUri);
-    final String nnServiceName = conf.get(key);
+    final String nnServiceName = conf.get(SERVICE_NAME_KEY + serviceName);
     
     int nnRpcPort = NameNode.DEFAULT_PORT;
     if (nnServiceName != null) {
       nnRpcPort = NetUtils.createSocketAddr(nnServiceName, nnRpcPort).getPort(); 
     }
+    // use original hostname from the uri to avoid unintentional host resolving
+    serviceName = SecurityUtil.buildTokenService(
+    		NetUtils.createSocketAddrForHost(nnUri.getHost(), nnRpcPort));
     
-    final Text serviceName = SecurityUtil.buildTokenService(
+    return selectToken(serviceName, tokens);
-        new InetSocketAddress(nnAddr.getHostName(), nnRpcPort));
-    return INSTANCE.selectToken(serviceName, ugi.getTokens());
-  }
-  
-  public static Token<DelegationTokenIdentifier> selectHdfsDelegationToken(
-      Text serviceName, UserGroupInformation ugi) {
-    return INSTANCE.selectToken(serviceName, ugi.getTokens());
   }
 
   public DelegationTokenSelector() {

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/ha/ConfiguredFailoverProxyProvider.java

@@ -22,6 +22,7 @@
 import java.net.InetSocketAddress;
 import java.net.URI;
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 
@@ -93,14 +94,15 @@ public ConfiguredFailoverProxyProvider(Configuration conf, URI uri,
             "for URI " + uri);
       }
       
-      for (InetSocketAddress address : addressesInNN.values()) {
+      Collection<InetSocketAddress> addressesOfNns = addressesInNN.values();
+      for (InetSocketAddress address : addressesOfNns) {
         proxies.add(new AddressRpcProxyPair<T>(address));
-        
-        // The client may have a delegation token set for the logical
-        // URI of the cluster. Clone this token to apply to each of the
-        // underlying IPC addresses so that the IPC code can find it.
-        HAUtil.cloneDelegationTokenForLogicalUri(ugi, uri, address);
       }
+
+      // The client may have a delegation token set for the logical
+      // URI of the cluster. Clone this token to apply to each of the
+      // underlying IPC addresses so that the IPC code can find it.
+      HAUtil.cloneDelegationTokenForLogicalUri(ugi, uri, addressesOfNns);
     } catch (IOException e) {
       throw new RuntimeException(e);
     }

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/web/WebHdfsFileSystem.java

@@ -29,6 +29,7 @@
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.net.URL;
+import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 import java.util.StringTokenizer;
@@ -117,8 +118,8 @@ public class WebHdfsFileSystem extends FileSystem
   /** Delegation token kind */
   public static final Text TOKEN_KIND = new Text("WEBHDFS delegation");
   /** Token selector */
-  public static final AbstractDelegationTokenSelector<DelegationTokenIdentifier> DT_SELECTOR
+  public static final WebHdfsDelegationTokenSelector DT_SELECTOR
-      = new AbstractDelegationTokenSelector<DelegationTokenIdentifier>(TOKEN_KIND) {};
+      = new WebHdfsDelegationTokenSelector();
 
   private static DelegationTokenRenewer<WebHdfsFileSystem> DT_RENEWER = null;
 
@@ -164,7 +165,7 @@ public synchronized void initialize(URI uri, Configuration conf
     } catch (URISyntaxException e) {
       throw new IllegalArgumentException(e);
     }
-    this.nnAddr = NetUtils.createSocketAddr(uri.toString());
+    this.nnAddr = NetUtils.createSocketAddrForHost(uri.getHost(), uri.getPort());
     this.workingDir = getHomeDirectory();
 
     if (UserGroupInformation.isSecurityEnabled()) {
@@ -174,12 +175,7 @@ public synchronized void initialize(URI uri, Configuration conf
 
   protected void initDelegationToken() throws IOException {
     // look for webhdfs token, then try hdfs
-    final Text serviceName = SecurityUtil.buildTokenService(nnAddr);
+    Token<?> token = selectDelegationToken();
-    Token<?> token = DT_SELECTOR.selectToken(serviceName, ugi.getTokens());      
-    if (token == null) {
-      token = DelegationTokenSelector.selectHdfsDelegationToken(
-          nnAddr, ugi, getConf());
-    }
 
     //since we don't already have a token, go get one
     boolean createdToken = false;
@@ -200,6 +196,10 @@ protected void initDelegationToken() throws IOException {
     }
   }
 
+  protected Token<DelegationTokenIdentifier> selectDelegationToken() {
+    return DT_SELECTOR.selectToken(getUri(), ugi.getTokens(), getConf());
+  }
+
   @Override
   protected int getDefaultPort() {
     return getConf().getInt(DFSConfigKeys.DFS_NAMENODE_HTTP_PORT_KEY,
@@ -845,4 +845,24 @@ public void cancel(final Token<?> token, final Configuration conf
       }
     }
   }
+  
+  private static class WebHdfsDelegationTokenSelector
+  extends AbstractDelegationTokenSelector<DelegationTokenIdentifier> {
+    private static final DelegationTokenSelector hdfsTokenSelector =
+        new DelegationTokenSelector();
+    
+    public WebHdfsDelegationTokenSelector() {
+      super(TOKEN_KIND);
+    }
+    
+    Token<DelegationTokenIdentifier> selectToken(URI nnUri,
+        Collection<Token<?>> tokens, Configuration conf) {
+      Token<DelegationTokenIdentifier> token =
+          selectToken(SecurityUtil.buildTokenService(nnUri), tokens);
+      if (token == null) {
+        token = hdfsTokenSelector.selectToken(nnUri, tokens, conf); 
+      }
+      return token;
+    }
+  }
 }

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/MiniDFSCluster.java

@@ -94,6 +94,7 @@
 import org.apache.hadoop.net.DNSToSwitchMapping;
 import org.apache.hadoop.net.NetUtils;
 import org.apache.hadoop.net.StaticMapping;
+import org.apache.hadoop.security.SecurityUtil;
 import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.security.authorize.ProxyUsers;
 import org.apache.hadoop.util.StringUtils;
@@ -1049,16 +1050,14 @@ public synchronized void startDataNodes(Configuration conf, int numDataNodes,
       if(dn == null)
         throw new IOException("Cannot start DataNode in "
             + dnConf.get(DFS_DATANODE_DATA_DIR_KEY));
-      //NOTE: the following is true if and only if:
+      //since the HDFS does things based on host|ip:port, we need to add the
-      //      hadoop.security.token.service.use_ip=true
+      //mapping for the service to rackId
-      //since the HDFS does things based on IP:port, we need to add the mapping
+      String service =
-      //for IP:port to rackId
+          SecurityUtil.buildTokenService(dn.getXferAddress()).toString();
-      String ipAddr = dn.getXferAddress().getAddress().getHostAddress();
       if (racks != null) {
-        int port = dn.getXferAddress().getPort();
+        LOG.info("Adding node with service : " + service +
-        LOG.info("Adding node with IP:port : " + ipAddr + ":" + port +
                             " to rack " + racks[i-curDatanodesNum]);
-        StaticMapping.addNodeToRack(ipAddr + ":" + port,
+        StaticMapping.addNodeToRack(service,
                                   racks[i-curDatanodesNum]);
       }
       dn.runDatanodeDaemon();

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestHftpDelegationToken.java

@@ -31,6 +31,7 @@
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.hdfs.security.token.delegation.DelegationTokenIdentifier;
 import org.apache.hadoop.io.Text;
+import org.apache.hadoop.security.SecurityUtilTestHelper;
 import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.security.token.Token;
 import org.apache.hadoop.security.token.TokenIdentifier;
@@ -66,4 +67,59 @@ public FileSystem run() throws Exception {
     renewToken.setAccessible(true);
     assertSame("wrong token", token, renewToken.get(fs));
   }
+
+  @Test
+  public void testSelectHdfsDelegationToken() throws Exception {
+    SecurityUtilTestHelper.setTokenServiceUseIp(true);
+
+    Configuration conf = new Configuration();
+    URI hftpUri = URI.create("hftp://localhost:0");
+    UserGroupInformation ugi = UserGroupInformation.getCurrentUser();
+    Token<?> token = null;
+    
+    // test fallback to hdfs token
+    Token<?> hdfsToken = new Token<TokenIdentifier>(
+        new byte[0], new byte[0],
+        DelegationTokenIdentifier.HDFS_DELEGATION_KIND,
+        new Text("127.0.0.1:8020"));
+    ugi.addToken(hdfsToken);
+    
+    HftpFileSystem fs = (HftpFileSystem) FileSystem.get(hftpUri, conf);
+    token = fs.selectDelegationToken();
+    assertNotNull(token);
+    assertEquals(hdfsToken, token);
+    
+    // test hftp is favored over hdfs
+    Token<?> hftpToken = new Token<TokenIdentifier>(
+        new byte[0], new byte[0],
+        HftpFileSystem.TOKEN_KIND, new Text("127.0.0.1:0"));
+    ugi.addToken(hftpToken);
+    token = fs.selectDelegationToken();
+    assertNotNull(token);
+    assertEquals(hftpToken, token);
+    
+    // switch to using host-based tokens, no token should match
+    SecurityUtilTestHelper.setTokenServiceUseIp(false);
+    token = fs.selectDelegationToken();
+    assertNull(token);
+    
+    // test fallback to hdfs token
+    hdfsToken = new Token<TokenIdentifier>(
+        new byte[0], new byte[0],
+        DelegationTokenIdentifier.HDFS_DELEGATION_KIND,
+        new Text("localhost:8020"));
+    ugi.addToken(hdfsToken);
+    token = fs.selectDelegationToken();
+    assertNotNull(token);
+    assertEquals(hdfsToken, token);
+
+    // test hftp is favored over hdfs
+    hftpToken = new Token<TokenIdentifier>(
+        new byte[0], new byte[0],
+        HftpFileSystem.TOKEN_KIND, new Text("localhost:0"));
+    ugi.addToken(hftpToken);
+    token = fs.selectDelegationToken();
+    assertNotNull(token);
+    assertEquals(hftpToken, token);
+  }
 }

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/security/TestClientProtocolWithDelegationToken.java

@@ -41,6 +41,7 @@
 import org.apache.hadoop.security.SaslInputStream;
 import org.apache.hadoop.security.SaslRpcClient;
 import org.apache.hadoop.security.SaslRpcServer;
+import org.apache.hadoop.security.SecurityUtil;
 import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.security.token.Token;
 import org.apache.log4j.Level;
@@ -91,10 +92,8 @@ public void testDelegationTokenRpc() throws Exception {
     DelegationTokenIdentifier dtId = new DelegationTokenIdentifier(owner, owner, null);
     Token<DelegationTokenIdentifier> token = new Token<DelegationTokenIdentifier>(
         dtId, sm);
-    Text host = new Text(addr.getAddress().getHostAddress() + ":"
+    SecurityUtil.setTokenService(token, addr);
-        + addr.getPort());
+    LOG.info("Service for token is " + token.getService());
-    token.setService(host);
-    LOG.info("Service IP address for token is " + host);
     current.addToken(token);
     current.doAs(new PrivilegedExceptionAction<Object>() {
       @Override

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/ha/TestDelegationTokensWithHA.java

@@ -26,6 +26,7 @@
 import java.net.URI;
 import java.security.PrivilegedExceptionAction;
 import java.util.Collection;
+import java.util.HashSet;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -44,11 +45,13 @@
 import org.apache.hadoop.hdfs.server.namenode.NameNodeAdapter;
 import org.apache.hadoop.io.Text;
 import org.apache.hadoop.security.SecurityUtil;
+import org.apache.hadoop.security.SecurityUtilTestHelper;
 import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.security.token.Token;
 import org.apache.hadoop.security.token.TokenIdentifier;
 import org.apache.hadoop.test.GenericTestUtils;
 import org.junit.AfterClass;
+import org.junit.Before;
 import org.junit.BeforeClass;
 import org.junit.Test;
 
@@ -100,6 +103,11 @@ public static void shutdownCluster() throws IOException {
   }
 
 
+  @Before
+  public void prepTest() {
+    SecurityUtilTestHelper.setTokenServiceUseIp(true);
+  }
+  
   @Test
   public void testDelegationTokenDFSApi() throws Exception {
     Token<DelegationTokenIdentifier> token = dfs.getDelegationToken("JobTracker");
@@ -187,23 +195,48 @@ public void testHAUtilClonesDelegationTokens() throws Exception {
     URI haUri = new URI("hdfs://my-ha-uri/");
     token.setService(HAUtil.buildTokenServiceForLogicalUri(haUri));
     ugi.addToken(token);
-    HAUtil.cloneDelegationTokenForLogicalUri(ugi, haUri, nn0.getNameNodeAddress());
+
-    HAUtil.cloneDelegationTokenForLogicalUri(ugi, haUri, nn1.getNameNodeAddress());
+    Collection<InetSocketAddress> nnAddrs = new HashSet<InetSocketAddress>();
+    nnAddrs.add(nn0.getNameNodeAddress());
+    nnAddrs.add(nn1.getNameNodeAddress());
+    HAUtil.cloneDelegationTokenForLogicalUri(ugi, haUri, nnAddrs);
     
     Collection<Token<? extends TokenIdentifier>> tokens = ugi.getTokens();
     assertEquals(3, tokens.size());
     
     LOG.info("Tokens:\n" + Joiner.on("\n").join(tokens));
+    DelegationTokenSelector dts = new DelegationTokenSelector();
     
     // check that the token selected for one of the physical IPC addresses
     // matches the one we received
-    InetSocketAddress addr = nn0.getNameNodeAddress();
+    for (InetSocketAddress addr : nnAddrs) {
-    Text ipcDtService = SecurityUtil.buildTokenService(addr);
+      Text ipcDtService = SecurityUtil.buildTokenService(addr);
-    Token<DelegationTokenIdentifier> token2 =
+      Token<DelegationTokenIdentifier> token2 =
-        DelegationTokenSelector.selectHdfsDelegationToken(ipcDtService, ugi);
+          dts.selectToken(ipcDtService, ugi.getTokens());
-    assertNotNull(token2);
+      assertNotNull(token2);
-    assertArrayEquals(token.getIdentifier(), token2.getIdentifier());
+      assertArrayEquals(token.getIdentifier(), token2.getIdentifier());
-    assertArrayEquals(token.getPassword(), token2.getPassword());
+      assertArrayEquals(token.getPassword(), token2.getPassword());
+    }
+    
+    // switch to host-based tokens, shouldn't match existing tokens 
+    SecurityUtilTestHelper.setTokenServiceUseIp(false);
+    for (InetSocketAddress addr : nnAddrs) {
+      Text ipcDtService = SecurityUtil.buildTokenService(addr);
+      Token<DelegationTokenIdentifier> token2 =
+          dts.selectToken(ipcDtService, ugi.getTokens());
+      assertNull(token2);
+    }
+    
+    // reclone the tokens, and see if they match now
+    HAUtil.cloneDelegationTokenForLogicalUri(ugi, haUri, nnAddrs);
+    for (InetSocketAddress addr : nnAddrs) {
+      Text ipcDtService = SecurityUtil.buildTokenService(addr);
+      Token<DelegationTokenIdentifier> token2 =
+          dts.selectToken(ipcDtService, ugi.getTokens());
+      assertNotNull(token2);
+      assertArrayEquals(token.getIdentifier(), token2.getIdentifier());
+      assertArrayEquals(token.getPassword(), token2.getPassword());
+    }    
   }
 
   /**

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/web/TestWebHdfsUrl.java

@@ -34,10 +34,16 @@
 import org.apache.hadoop.hdfs.web.resources.HttpOpParam;
 import org.apache.hadoop.hdfs.web.resources.PutOpParam;
 import org.apache.hadoop.io.Text;
+import org.apache.hadoop.security.SecurityUtilTestHelper;
 import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.security.token.Token;
+import org.apache.hadoop.security.token.TokenIdentifier;
 import org.junit.Assert;
 import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
 import static org.mockito.Mockito.mock;
 
 public class TestWebHdfsUrl {
@@ -90,4 +96,60 @@ public void testDelegationTokenInUrl() throws IOException {
   private String generateUrlQueryPrefix(HttpOpParam.Op op, String username) {
     return "op=" + op.toString() + "&user.name=" + username;
   }
+  
+  @Test
+  public void testSelectDelegationToken() throws Exception {
+    SecurityUtilTestHelper.setTokenServiceUseIp(true);
+
+    Configuration conf = new Configuration();
+    URI webHdfsUri = URI.create("webhdfs://localhost:0");
+    UserGroupInformation ugi = UserGroupInformation.getCurrentUser();
+    Token<?> token = null;
+    
+    // test fallback to hdfs token
+    Token<?> hdfsToken = new Token<TokenIdentifier>(
+        new byte[0], new byte[0],
+        DelegationTokenIdentifier.HDFS_DELEGATION_KIND,
+        new Text("127.0.0.1:8020"));
+    ugi.addToken(hdfsToken);
+    
+    WebHdfsFileSystem fs = (WebHdfsFileSystem) FileSystem.get(webHdfsUri, conf);
+    token = fs.selectDelegationToken();
+    assertNotNull(token);
+    assertEquals(hdfsToken, token);
+    
+    // test webhdfs is favored over hdfs
+    Token<?> webHdfsToken = new Token<TokenIdentifier>(
+        new byte[0], new byte[0],
+        WebHdfsFileSystem.TOKEN_KIND, new Text("127.0.0.1:0"));
+    ugi.addToken(webHdfsToken);
+    token = fs.selectDelegationToken();
+    assertNotNull(token);
+    assertEquals(webHdfsToken, token);
+    
+    // switch to using host-based tokens, no token should match
+    SecurityUtilTestHelper.setTokenServiceUseIp(false);
+    token = fs.selectDelegationToken();
+    assertNull(token);
+    
+    // test fallback to hdfs token
+    hdfsToken = new Token<TokenIdentifier>(
+        new byte[0], new byte[0],
+        DelegationTokenIdentifier.HDFS_DELEGATION_KIND,
+        new Text("localhost:8020"));
+    ugi.addToken(hdfsToken);
+    token = fs.selectDelegationToken();
+    assertNotNull(token);
+    assertEquals(hdfsToken, token);
+
+    // test webhdfs is favored over hdfs
+    webHdfsToken = new Token<TokenIdentifier>(
+        new byte[0], new byte[0],
+        WebHdfsFileSystem.TOKEN_KIND, new Text("localhost:0"));
+    ugi.addToken(webHdfsToken);
+    token = fs.selectDelegationToken();
+    assertNotNull(token);
+    assertEquals(webHdfsToken, token);
+  }
+
 }