/* * Copyright (c) 2006, 2009, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */package sun.security.krb5;import java.util.Arrays;import java.util.Enumeration;import java.util.Hashtable;import java.util.NoSuchElementException;import java.util.Random;import java.util.StringTokenizer;import java.util.List;import javax.naming.*;import javax.naming.directory.*;import javax.naming.spi.NamingManager;/** * This class discovers the location of Kerberos services by querying DNS, * as defined in RFC 4120. * * @author Seema Malkani * @since 1.7 */class KrbServiceLocator { private static final String SRV_RR = "SRV"; private static final String[] SRV_RR_ATTR = new String[] {SRV_RR}; private static final String SRV_TXT = "TXT"; private static final String[] SRV_TXT_ATTR = new String[] {SRV_TXT}; private static final Random random = new Random(); private KrbServiceLocator() { } /** * Locates the KERBEROS service for a given domain. * Queries DNS for a list of KERBEROS Service Text Records (TXT) for a * given domain name. * Information on the mapping of DNS hostnames and domain names * to Kerberos realms is stored using DNS TXT records * * @param domainName A string domain name. * @param environment The possibly null environment of the context. * @return An ordered list of hostports for the Kerberos service or null if * the service has not been located. */ static String[] getKerberosService(String realmName) { // search realm in SRV TXT records String dnsUrl = "dns:///_kerberos." + realmName; String[] records = null; try { // Create the DNS context using NamingManager rather than using // the initial context constructor. This avoids having the initial // context constructor call itself (when processing the URL // argument in the getAttributes call). Context ctx = NamingManager.getURLContext("dns", new Hashtable(0)); if (!(ctx instanceof DirContext)) { return null; // cannot create a DNS context } Attributes attrs = ((DirContext)ctx).getAttributes(dnsUrl, SRV_TXT_ATTR); Attribute attr; if (attrs != null && ((attr = attrs.get(SRV_TXT)) != null)) { int numValues = attr.size(); int numRecords = 0; String[] txtRecords = new String[numValues]; // gather the text records int i = 0; int j = 0; while (i < numValues) { try { txtRecords[j] = (String)attr.get(i); j++; } catch (Exception e) { // ignore bad value } i++; } numRecords = j; // trim if (numRecords < numValues) { String[] trimmed = new String[numRecords]; System.arraycopy(txtRecords, 0, trimmed, 0, numRecords); records = trimmed; } else { records = txtRecords; } } } catch (NamingException e) { // ignore } return records; } /** * Locates the KERBEROS service for a given domain. * Queries DNS for a list of KERBEROS Service Location Records (SRV) for a * given domain name. * * @param domainName A string domain name. * @return An ordered list of hostports for the Kerberos service or null if * the service has not been located. */ static String[] getKerberosService(String realmName, String protocol) { String dnsUrl = "dns:///_kerberos." + protocol + "." + realmName; String[] hostports = null; try { // Create the DNS context using NamingManager rather than using // the initial context constructor. This avoids having the initial // context constructor call itself (when processing the URL // argument in the getAttributes call). Context ctx = NamingManager.getURLContext("dns", new Hashtable(0)); if (!(ctx instanceof DirContext)) { return null; // cannot create a DNS context } Attributes attrs = ((DirContext)ctx).getAttributes(dnsUrl, SRV_RR_ATTR); Attribute attr; if (attrs != null && ((attr = attrs.get(SRV_RR)) != null)) { int numValues = attr.size(); int numRecords = 0; SrvRecord[] srvRecords = new SrvRecord[numValues]; // create the service records int i = 0; int j = 0; while (i < numValues) { try { srvRecords[j] = new SrvRecord((String) attr.get(i)); j++; } catch (Exception e) { // ignore bad value } i++; } numRecords = j; // trim if (numRecords < numValues) { SrvRecord[] trimmed = new SrvRecord[numRecords]; System.arraycopy(srvRecords, 0, trimmed, 0, numRecords); srvRecords = trimmed; } // Sort the service records in ascending order of their // priority value. For records with equal priority, move // those with weight 0 to the top of the list. if (numRecords > 1) { Arrays.sort(srvRecords); } // extract the host and port number from each service record hostports = extractHostports(srvRecords); } } catch (NamingException e) { // e.printStackTrace(); // ignore } return hostports; } /** * Extract hosts and port numbers from a list of SRV records. * An array of hostports is returned or null if none were found. */ private static String[] extractHostports(SrvRecord[] srvRecords) { String[] hostports = null; int head = 0; int tail = 0; int sublistLength = 0; int k = 0; for (int i = 0; i < srvRecords.length; i++) { if (hostports == null) { hostports = new String[srvRecords.length]; } // find the head and tail of the list of records having the same // priority value. head = i; while (i < srvRecords.length - 1 && srvRecords[i].priority == srvRecords[i + 1].priority) { i++; } tail = i; // select hostports from the sublist sublistLength = (tail - head) + 1; for (int j = 0; j < sublistLength; j++) { hostports[k++] = selectHostport(srvRecords, head, tail); } } return hostports; } /* * Randomly select a service record in the range [head, tail] and return * its hostport value. Follows the algorithm in RFC 2782. */ private static String selectHostport(SrvRecord[] srvRecords, int head, int tail) { if (head == tail) { return srvRecords[head].hostport; } // compute the running sum for records between head and tail int sum = 0; for (int i = head; i <= tail; i++) { if (srvRecords[i] != null) { sum += srvRecords[i].weight; srvRecords[i].sum = sum; } } String hostport = null; // If all records have zero weight, select first available one; // otherwise, randomly select a record according to its weight int target = (sum == 0 ? 0 : random.nextInt(sum + 1)); for (int i = head; i <= tail; i++) { if (srvRecords[i] != null && srvRecords[i].sum >= target) { hostport = srvRecords[i].hostport; srvRecords[i] = null; // make this record unavailable break; } } return hostport; }/** * This class holds a DNS service (SRV) record. * See http://www.ietf.org/rfc/rfc2782.txt */static class SrvRecord implements Comparable { int priority; int weight; int sum; String hostport; /** * Creates a service record object from a string record. * DNS supplies the string record in the following format: * <pre> * <Priority> " " <Weight> " " <Port> " " <Host> * </pre> */ SrvRecord(String srvRecord) throws Exception { StringTokenizer tokenizer = new StringTokenizer(srvRecord, " "); String port; if (tokenizer.countTokens() == 4) { priority = Integer.parseInt(tokenizer.nextToken()); weight = Integer.parseInt(tokenizer.nextToken()); port = tokenizer.nextToken(); hostport = tokenizer.nextToken() + ":" + port; } else { throw new IllegalArgumentException(); } } /* * Sort records in ascending order of priority value. For records with * equal priority move those with weight 0 to the top of the list. */ public int compareTo(Object o) { SrvRecord that = (SrvRecord) o; if (priority > that.priority) { return 1; // this > that } else if (priority < that.priority) { return -1; // this < that } else if (weight == 0 && that.weight != 0) { return -1; // this < that } else if (weight != 0 && that.weight == 0) { return 1; // this > that } else { return 0; // this == that } }}}
/*
* Copyright (c) 2006, 2009, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package sun.security.krb5;
import java.util.Arrays;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.NoSuchElementException;
import java.util.Random;
import java.util.StringTokenizer;
import java.util.List;
import javax.naming.*;
import javax.naming.directory.*;
import javax.naming.spi.NamingManager;
/**
* This class discovers the location of Kerberos services by querying DNS,
* as defined in RFC 4120.
*
* @author Seema Malkani
* @since 1.7
*/
class KrbServiceLocator {
private static final String SRV_RR = "SRV";
private static final String[] SRV_RR_ATTR = new String[] {SRV_RR};
private static final String SRV_TXT = "TXT";
private static final String[] SRV_TXT_ATTR = new String[] {SRV_TXT};
private static final Random random = new Random();
private KrbServiceLocator() {
}
/**
* Locates the KERBEROS service for a given domain.
* Queries DNS for a list of KERBEROS Service Text Records (TXT) for a
* given domain name.
* Information on the mapping of DNS hostnames and domain names
* to Kerberos realms is stored using DNS TXT records
*
* @param domainName A string domain name.
* @param environment The possibly null environment of the context.
* @return An ordered list of hostports for the Kerberos service or null if
* the service has not been located.
*/
static String[] getKerberosService(String realmName) {
// search realm in SRV TXT records
String dnsUrl = "dns:///_kerberos." + realmName;
String[] records = null;
try {
// Create the DNS context using NamingManager rather than using
// the initial context constructor. This avoids having the initial
// context constructor call itself (when processing the URL
// argument in the getAttributes call).
Context ctx = NamingManager.getURLContext("dns", new Hashtable(0));
if (!(ctx instanceof DirContext)) {
return null; // cannot create a DNS context
}
Attributes attrs =
((DirContext)ctx).getAttributes(dnsUrl, SRV_TXT_ATTR);
Attribute attr;
if (attrs != null && ((attr = attrs.get(SRV_TXT)) != null)) {
int numValues = attr.size();
int numRecords = 0;
String[] txtRecords = new String[numValues];
// gather the text records
int i = 0;
int j = 0;
while (i < numValues) {
try {
txtRecords[j] = (String)attr.get(i);
j++;
} catch (Exception e) {
// ignore bad value
}
i++;
}
numRecords = j;
// trim
if (numRecords < numValues) {
String[] trimmed = new String[numRecords];
System.arraycopy(txtRecords, 0, trimmed, 0, numRecords);
records = trimmed;
} else {
records = txtRecords;
}
}
} catch (NamingException e) {
// ignore
}
return records;
}
/**
* Locates the KERBEROS service for a given domain.
* Queries DNS for a list of KERBEROS Service Location Records (SRV) for a
* given domain name.
*
* @param domainName A string domain name.
* @return An ordered list of hostports for the Kerberos service or null if
* the service has not been located.
*/
static String[] getKerberosService(String realmName, String protocol) {
String dnsUrl = "dns:///_kerberos." + protocol + "." + realmName;
String[] hostports = null;
try {
// Create the DNS context using NamingManager rather than using
// the initial context constructor. This avoids having the initial
// context constructor call itself (when processing the URL
// argument in the getAttributes call).
Context ctx = NamingManager.getURLContext("dns", new Hashtable(0));
if (!(ctx instanceof DirContext)) {
return null; // cannot create a DNS context
}
Attributes attrs =
((DirContext)ctx).getAttributes(dnsUrl, SRV_RR_ATTR);
Attribute attr;
if (attrs != null && ((attr = attrs.get(SRV_RR)) != null)) {
int numValues = attr.size();
int numRecords = 0;
SrvRecord[] srvRecords = new SrvRecord[numValues];
// create the service records
int i = 0;
int j = 0;
while (i < numValues) {
try {
srvRecords[j] = new SrvRecord((String) attr.get(i));
j++;
} catch (Exception e) {
// ignore bad value
}
i++;
}
numRecords = j;
// trim
if (numRecords < numValues) {
SrvRecord[] trimmed = new SrvRecord[numRecords];
System.arraycopy(srvRecords, 0, trimmed, 0, numRecords);
srvRecords = trimmed;
}
// Sort the service records in ascending order of their
// priority value. For records with equal priority, move
// those with weight 0 to the top of the list.
if (numRecords > 1) {
Arrays.sort(srvRecords);
}
// extract the host and port number from each service record
hostports = extractHostports(srvRecords);
}
} catch (NamingException e) {
// e.printStackTrace();
// ignore
}
return hostports;
}
/**
* Extract hosts and port numbers from a list of SRV records.
* An array of hostports is returned or null if none were found.
*/
private static String[] extractHostports(SrvRecord[] srvRecords) {
String[] hostports = null;
int head = 0;
int tail = 0;
int sublistLength = 0;
int k = 0;
for (int i = 0; i < srvRecords.length; i++) {
if (hostports == null) {
hostports = new String[srvRecords.length];
}
// find the head and tail of the list of records having the same
// priority value.
head = i;
while (i < srvRecords.length - 1 &&
srvRecords[i].priority == srvRecords[i + 1].priority) {
i++;
}
tail = i;
// select hostports from the sublist
sublistLength = (tail - head) + 1;
for (int j = 0; j < sublistLength; j++) {
hostports[k++] = selectHostport(srvRecords, head, tail);
}
}
return hostports;
}
/*
* Randomly select a service record in the range [head, tail] and return
* its hostport value. Follows the algorithm in RFC 2782.
*/
private static String selectHostport(SrvRecord[] srvRecords, int head,
int tail) {
if (head == tail) {
return srvRecords[head].hostport;
}
// compute the running sum for records between head and tail
int sum = 0;
for (int i = head; i <= tail; i++) {
if (srvRecords[i] != null) {
sum += srvRecords[i].weight;
srvRecords[i].sum = sum;
}
}
String hostport = null;
// If all records have zero weight, select first available one;
// otherwise, randomly select a record according to its weight
int target = (sum == 0 ? 0 : random.nextInt(sum + 1));
for (int i = head; i <= tail; i++) {
if (srvRecords[i] != null && srvRecords[i].sum >= target) {
hostport = srvRecords[i].hostport;
srvRecords[i] = null; // make this record unavailable
break;
}
}
return hostport;
}
/**
* This class holds a DNS service (SRV) record.
* See http://www.ietf.org/rfc/rfc2782.txt
*/
static class SrvRecord implements Comparable {
int priority;
int weight;
int sum;
String hostport;
/**
* Creates a service record object from a string record.
* DNS supplies the string record in the following format:
* <pre>
* <Priority> " " <Weight> " " <Port> " " <Host>
* </pre>
*/
SrvRecord(String srvRecord) throws Exception {
StringTokenizer tokenizer = new StringTokenizer(srvRecord, " ");
String port;
if (tokenizer.countTokens() == 4) {
priority = Integer.parseInt(tokenizer.nextToken());
weight = Integer.parseInt(tokenizer.nextToken());
port = tokenizer.nextToken();
hostport = tokenizer.nextToken() + ":" + port;
} else {
throw new IllegalArgumentException();
}
}
/*
* Sort records in ascending order of priority value. For records with
* equal priority move those with weight 0 to the top of the list.
*/
public int compareTo(Object o) {
SrvRecord that = (SrvRecord) o;
if (priority > that.priority) {
return 1; // this > that
} else if (priority < that.priority) {
return -1; // this < that
} else if (weight == 0 && that.weight != 0) {
return -1; // this < that
} else if (weight != 0 && that.weight == 0) {
return 1; // this > that
} else {
return 0; // this == that
}
}
}
}