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6957564: Disclosure of DNS server IP address

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Reviewed-by: xuelei, chegar
This commit is contained in:
Weijun Wang 2010-06-17 12:59:14 +08:00
parent 5d45157e24
commit c218e4488e
1 changed files with 46 additions and 3 deletions
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49
jdk/src/share/classes/com/sun/jndi/dns/DnsContextFactory.java
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@ -54,6 +54,7 @@ import sun.net.dns.ResolverConfiguration; // available since 1.4.1
public class DnsContextFactory implements InitialContextFactory {
private static final String DEFAULT_URL = "dns:";
private static final int DEFAULT_PORT = 53;
public Context getInitialContext(Hashtable<?,?> env) throws NamingException {
@ -89,7 +90,9 @@ public class DnsContextFactory implements InitialContextFactory {
* Public for use by product test suite.
*/
public static boolean platformServersAvailable() {
return !ResolverConfiguration.open().nameservers().isEmpty();
return !filterNameServers(
ResolverConfiguration.open().nameservers(), true
).isEmpty();
}
private static Context urlToContext(String url, Hashtable env)
@ -142,8 +145,8 @@ public class DnsContextFactory implements InitialContextFactory {
// No server or port given, so look to underlying platform.
// ResolverConfiguration does some limited caching, so the
// following is reasonably efficient even if called rapid-fire.
List platformServers =
ResolverConfiguration.open().nameservers();
List platformServers = filterNameServers(
ResolverConfiguration.open().nameservers(), false);
if (!platformServers.isEmpty()) {
servers.addAll(platformServers);
continue; // on to next URL (if any, which is unlikely)
@ -214,4 +217,44 @@ public class DnsContextFactory implements InitialContextFactory {
String url = (String) env.get(Context.PROVIDER_URL);
return ((url != null) ? url : DEFAULT_URL);
}
/**
* Removes any DNS server that's not permitted to access
* @param input the input server[:port] list, must not be null
* @param oneIsEnough return output once there exists one ok
* @return the filtered list, all non-permitted input removed
*/
private static List filterNameServers(List input, boolean oneIsEnough) {
SecurityManager security = System.getSecurityManager();
if (security == null || input == null || input.isEmpty()) {
return input;
} else {
List output = new ArrayList();
for (Object o: input) {
if (o instanceof String) {
String platformServer = (String)o;
int colon = platformServer.indexOf(':',
platformServer.indexOf(']') + 1);
int p = (colon < 0)
? DEFAULT_PORT
: Integer.parseInt(
platformServer.substring(colon + 1));
String s = (colon < 0)
? platformServer
: platformServer.substring(0, colon);
try {
security.checkConnect(s, p);
output.add(platformServer);
if (oneIsEnough) {
return output;
}
} catch (SecurityException se) {
continue;
}
}
}
return output;
}
}
}