[PATCH] 7006496: Use modern Windows API to retrieve OS DNS servers

Anuraag Agrawal anuraaga at gmail.com
Thu Dec 12 13:26:35 UTC 2019


Hi Aleksei,

I've gone ahead and moved the site-local check to native code - it does
reduce the chance of filling up our buffer, though the code is a bit more
complicated. To get sockaddr_in6, I went ahead and switched the imports to
net_util.h, which I noticed was used in other files. Let me know if it
looks ok.

Inline patch follows

diff --git
a/src/java.base/windows/classes/sun/net/dns/ResolverConfigurationImpl.java
b/src/java.base/windows/classes/sun/net/dns/ResolverConfigurationImpl.java
index 2250b3158e..c3ebe09776 100644
---
a/src/java.base/windows/classes/sun/net/dns/ResolverConfigurationImpl.java
+++
b/src/java.base/windows/classes/sun/net/dns/ResolverConfigurationImpl.java
@@ -25,9 +25,9 @@

 package sun.net.dns;

+import java.util.ArrayList;
 import java.util.List;
-import java.util.LinkedList;
-import java.util.StringTokenizer;
+import java.util.concurrent.TimeUnit;

 /*
  * An implementation of sun.net.ResolverConfiguration for Windows.
@@ -50,30 +50,55 @@ public class ResolverConfigurationImpl

     // Cache timeout (120 seconds) - should be converted into property
     // or configured as preference in the future.
-    private static final int TIMEOUT = 120000;
+    private static final long TIMEOUT_NANOS =
TimeUnit.SECONDS.toNanos(120);

     // DNS suffix list and name servers populated by native method
     private static String os_searchlist;
     private static String os_nameservers;

     // Cached lists
-    private static LinkedList<String> searchlist;
-    private static LinkedList<String> nameservers;
-
-    // Parse string that consists of token delimited by space or commas
-    // and return LinkedHashMap
-    private LinkedList<String> stringToList(String str) {
-        LinkedList<String> ll = new LinkedList<>();
-
-        // comma and space are valid delimiters
-        StringTokenizer st = new StringTokenizer(str, ", ");
-        while (st.hasMoreTokens()) {
-            String s = st.nextToken();
-            if (!ll.contains(s)) {
-                ll.add(s);
+    private static ArrayList<String> searchlist;
+    private static ArrayList<String> nameservers;
+
+    // Parse string that consists of token delimited by comma
+    // and return ArrayList. Refer to ResolverConfigurationImpl.c and
+    // strappend to see how the string is created.
+    private ArrayList<String> stringToList(String str) {
+        // String is delimited by comma.
+        String[] tokens = str.split(",");
+        ArrayList<String> l = new ArrayList<>(tokens.length);
+        for (String s : tokens) {
+            if (!l.contains(s)) {
+                l.add(s);
             }
         }
-        return ll;
+        l.trimToSize();
+        return l;
+    }
+
+    // Parse string that consists of token delimited by comma
+    // and return ArrayList.  Refer to ResolverConfigurationImpl.c and
+    // strappend to see how the string is created.
+    // In addition to splitting the string, converts IPv6 addresses to
+    // BSD-style.
+    private ArrayList<String> addressesToList(String str) {
+        // String is delimited by comma
+        String[] tokens = str.split(",");
+        ArrayList<String> l = new ArrayList<>(tokens.length);
+
+        for (String s : tokens) {
+            if (!s.isEmpty()) {
+                if (s.indexOf(':') >= 0 && s.charAt(0) != '[') {
+                    // Not BSD style
+                    s = '[' + s + ']';
+                }
+                if (!l.contains(s)) {
+                    l.add(s);
+                }
+            }
+        }
+        l.trimToSize();
+        return l;
     }

     // Load DNS configuration from OS
@@ -81,28 +106,34 @@ public class ResolverConfigurationImpl
     private void loadConfig() {
         assert Thread.holdsLock(lock);

-        // if address have changed then DNS probably changed as well;
-        // otherwise check if cached settings have expired.
-        //
+        // A change in the network address of the machine usually indicates
+        // a change in DNS configuration too so we always refresh the
config
+        // after such a change.
         if (changed) {
             changed = false;
         } else {
+            // Otherwise we refresh if TIMEOUT_NANOS has passed since last
+            // load.
             if (lastRefresh >= 0) {
-                long currTime = System.currentTimeMillis();
-                if ((currTime - lastRefresh) < TIMEOUT) {
+                long currTime = System.nanoTime();
+                if ((currTime - lastRefresh) < TIMEOUT_NANOS) {
                     return;
                 }
             }
         }

-        // load DNS configuration, update timestamp, create
-        // new HashMaps from the loaded configuration
-        //
+        // Native code that uses Windows API to find out the DNS server
+        // addresses and search suffixes. It builds a comma-delimited
string
+        // of nameservers and domain suffixes and sets them to the static
+        // os_nameservers and os_searchlist. We then split these into Java
+        // Lists here.
         loadDNSconfig0();

-        lastRefresh = System.currentTimeMillis();
+        // Record the time of update and refresh the lists of addresses /
+        // domain suffixes.
+        lastRefresh = System.nanoTime();
         searchlist = stringToList(os_searchlist);
-        nameservers = stringToList(os_nameservers);
+        nameservers = addressesToList(os_nameservers);
         os_searchlist = null;                       // can be GC'ed
         os_nameservers = null;
     }
diff --git a/src/java.base/windows/native/libnet/NetworkInterface_winXP.c
b/src/java.base/windows/native/libnet/NetworkInterface_winXP.c
index f2368bafcb..297a1561ef 100644
--- a/src/java.base/windows/native/libnet/NetworkInterface_winXP.c
+++ b/src/java.base/windows/native/libnet/NetworkInterface_winXP.c
@@ -73,8 +73,8 @@ const int MAX_TRIES = 3;
  * for each adapter on the system. Returned in *adapters.
  * Buffer is malloc'd and must be freed (unless error returned)
  */
-static int getAdapters (JNIEnv *env, IP_ADAPTER_ADDRESSES **adapters) {
-    DWORD ret, flags;
+int getAdapters (JNIEnv *env, int flags, IP_ADAPTER_ADDRESSES **adapters) {
+    DWORD ret;
     IP_ADAPTER_ADDRESSES *adapterInfo;
     ULONG len;
     int try;
@@ -87,9 +87,6 @@ static int getAdapters (JNIEnv *env, IP_ADAPTER_ADDRESSES
**adapters) {
     }

     len = BUFF_SIZE;
-    flags = GAA_FLAG_SKIP_DNS_SERVER;
-    flags |= GAA_FLAG_SKIP_MULTICAST;
-    flags |= GAA_FLAG_INCLUDE_PREFIX;
     ret = GetAdaptersAddresses(AF_UNSPEC, flags, NULL, adapterInfo, &len);

     for (try = 0; ret == ERROR_BUFFER_OVERFLOW && try < MAX_TRIES; ++try) {
@@ -240,7 +237,7 @@ static int ipinflen = 2048;
  */
 int getAllInterfacesAndAddresses (JNIEnv *env, netif **netifPP)
 {
-    DWORD ret;
+    DWORD ret, flags;
     MIB_IPADDRTABLE *tableP;
     IP_ADAPTER_ADDRESSES *ptr, *adapters=NULL;
     ULONG len=ipinflen, count=0;
@@ -296,7 +293,11 @@ int getAllInterfacesAndAddresses (JNIEnv *env, netif
**netifPP)
         }
     }
     free(tableP);
-    ret = getAdapters (env, &adapters);
+
+    flags = GAA_FLAG_SKIP_DNS_SERVER;
+    flags |= GAA_FLAG_SKIP_MULTICAST;
+    flags |= GAA_FLAG_INCLUDE_PREFIX;
+    ret = getAdapters (env, flags, &adapters);
     if (ret != ERROR_SUCCESS) {
         goto err;
     }
diff --git
a/src/java.base/windows/native/libnet/ResolverConfigurationImpl.c
b/src/java.base/windows/native/libnet/ResolverConfigurationImpl.c
index 13b28044a5..580347540d 100644
--- a/src/java.base/windows/native/libnet/ResolverConfigurationImpl.c
+++ b/src/java.base/windows/native/libnet/ResolverConfigurationImpl.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2013, Oracle and/or its affiliates. All rights
reserved.
+ * Copyright (c) 2002, 2019, 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
@@ -24,14 +24,12 @@
  */

 #include <stdlib.h>
-#include <windows.h>
 #include <stdio.h>
 #include <stddef.h>
-#include <iprtrmib.h>
 #include <time.h>
 #include <assert.h>
-#include <iphlpapi.h>

+#include "net_util.h"
 #include "jni_util.h"

 #define MAX_STR_LEN         256
@@ -48,8 +46,10 @@
 static jfieldID searchlistID;
 static jfieldID nameserversID;

+extern int getAdapters(JNIEnv *env, int flags, IP_ADAPTER_ADDRESSES
**adapters);
+
 /*
- * Utility routine to append s2 to s1 with a space delimiter.
+ * Utility routine to append s2 to s1 with a comma delimiter.
  *  strappend(s1="abc", "def")  => "abc def"
  *  strappend(s1="", "def")     => "def
  */
@@ -60,41 +60,32 @@ void strappend(char *s1, char *s2) {
         return;

     len = strlen(s1)+1;
-    if (s1[0] != 0)                         /* needs space character */
+    if (s1[0] != 0)                         /* needs comma character */
         len++;
     if (len + strlen(s2) > MAX_STR_LEN)     /* insufficient space */
         return;

     if (s1[0] != 0) {
-        strcat(s1, " ");
+        strcat(s1, ",");
     }
     strcat(s1, s2);
 }

 /*
- * Windows 2000/XP
- *
- * Use registry approach based on settings described in Appendix C
- * of "Microsoft Windows 2000 TCP/IP Implementation Details".
- *
- * DNS suffix list is obtained from SearchList registry setting. If
- * this is not specified we compile suffix list based on the
- * per-connection domain suffix.
- *
- * DNS name servers and domain settings are on a per-connection
- * basic. We therefore enumerate the network adapters to get the
- * names of each adapter and then query the corresponding registry
- * settings to obtain NameServer/DhcpNameServer and Domain/DhcpDomain.
+ * Use DNS server addresses returned by GetAdaptersAddresses for currently
+ * active interfaces.
  */
-static int loadConfig(char *sl, char *ns) {
-    IP_ADAPTER_INFO *adapterP;
-    ULONG size;
-    DWORD ret;
+static int loadConfig(JNIEnv *env, char *sl, char *ns) {
+    IP_ADAPTER_ADDRESSES *adapters, *adapter;
+    IP_ADAPTER_DNS_SERVER_ADDRESS *dnsServer;
+    WCHAR *suffix;
+    DWORD ret, flags;
     DWORD dwLen;
     ULONG ulType;
     char result[MAX_STR_LEN];
     HANDLE hKey;
-    int gotSearchList = 0;
+    SOCKADDR *sockAddr;
+    struct sockaddr_in6 *sockAddrIpv6;

     /*
      * First see if there is a global suffix list specified.
@@ -112,122 +103,67 @@ static int loadConfig(char *sl, char *ns) {
             assert(ulType == REG_SZ);
             if (strlen(result) > 0) {
                 strappend(sl, result);
-                gotSearchList = 1;
             }
         }
         RegCloseKey(hKey);
     }

-    /*
-     * Ask the IP Helper library to enumerate the adapters
-     */
-    size = sizeof(IP_ADAPTER_INFO);
-    adapterP = (IP_ADAPTER_INFO *)malloc(size);
-    if (adapterP == NULL) {
-        return STS_ERROR;
-    }
-    ret = GetAdaptersInfo(adapterP, &size);
-    if (ret == ERROR_BUFFER_OVERFLOW) {
-        IP_ADAPTER_INFO *newAdapterP = (IP_ADAPTER_INFO
*)realloc(adapterP, size);
-        if (newAdapterP == NULL) {
-            free(adapterP);
-            return STS_ERROR;
-        }
-        adapterP = newAdapterP;

-        ret = GetAdaptersInfo(adapterP, &size);
+    // We only need DNS server addresses so skip everything else.
+    flags = GAA_FLAG_SKIP_UNICAST;
+    flags |= GAA_FLAG_SKIP_ANYCAST;
+    flags |= GAA_FLAG_SKIP_MULTICAST;
+    flags |= GAA_FLAG_SKIP_FRIENDLY_NAME;
+    ret = getAdapters(env, flags, &adapters);
+    if (ret != ERROR_SUCCESS) {
+        return STS_ERROR;
     }

-    /*
-     * Iterate through the list of adapters as registry settings are
-     * keyed on the adapter name (GUID).
-     */
-    if (ret == ERROR_SUCCESS) {
-        IP_ADAPTER_INFO *curr = adapterP;
-        while (curr != NULL) {
-            char key[MAX_STR_LEN];
-
-            sprintf(key,
-
 "SYSTEM\\CurrentControlSet\\Services\\Tcpip\\Parameters\\Interfaces\\%s",
-                curr->AdapterName);
-
-            ret = RegOpenKeyEx(HKEY_LOCAL_MACHINE,
-                               key,
-                               0,
-                               KEY_READ,
-                               (PHKEY)&hKey);
-            if (ret == ERROR_SUCCESS) {
-                DWORD enableDhcp = 0;
-
-                /*
-                 * Is DHCP enabled on this interface
-                 */
-                dwLen = sizeof(enableDhcp);
-                ret = RegQueryValueEx(hKey, "EnableDhcp", NULL, &ulType,
-                                     (LPBYTE)&enableDhcp, &dwLen);
-
-                /*
-                 * If we don't have the suffix list when get the Domain
-                 * or DhcpDomain. If DHCP is enabled then Domain overides
-                 * DhcpDomain
-                 */
-                if (!gotSearchList) {
-                    result[0] = '\0';
-                    dwLen = sizeof(result);
-                    ret = RegQueryValueEx(hKey, "Domain", NULL, &ulType,
-                                         (LPBYTE)&result, &dwLen);
-                    if (((ret != ERROR_SUCCESS) || (strlen(result) == 0))
&&
-                        enableDhcp) {
-                        dwLen = sizeof(result);
-                        ret = RegQueryValueEx(hKey, "DhcpDomain", NULL,
&ulType,
-                                              (LPBYTE)&result, &dwLen);
-                    }
-                    if (ret == ERROR_SUCCESS) {
-                        assert(ulType == REG_SZ);
-                        strappend(sl, result);
+    adapter = adapters;
+    while (adapter != NULL) {
+        // Only load config from enabled adapters.
+        if (adapter->OperStatus == IfOperStatusUp) {
+            dnsServer = adapter->FirstDnsServerAddress;
+            while (dnsServer != NULL) {
+                sockAddr = dnsServer->Address.lpSockaddr;
+                if (sockAddr->sa_family == AF_INET6) {
+                    sockAddrIpv6 = (struct sockaddr_in6 *)sockAddr;
+                    if (sockAddrIpv6->sin6_scope_id != 0) {
+                        // An address with a scope is either link-local or
+                        // site-local, which aren't valid for DNS queries
so
+                        // we can skip them.
+                        dnsServer = dnsServer->Next;
+                        continue;
                     }
                 }

-                /*
-                 * Get DNS servers based on NameServer or DhcpNameServer
-                 * registry setting. If NameServer is set then it overrides
-                 * DhcpNameServer (even if DHCP is enabled).
-                 */
-                result[0] = '\0';
                 dwLen = sizeof(result);
-                ret = RegQueryValueEx(hKey, "NameServer", NULL, &ulType,
-                                     (LPBYTE)&result, &dwLen);
-                if (((ret != ERROR_SUCCESS) || (strlen(result) == 0)) &&
-                    enableDhcp) {
-                    dwLen = sizeof(result);
-                    ret = RegQueryValueEx(hKey, "DhcpNameServer", NULL,
&ulType,
-                                          (LPBYTE)&result, &dwLen);
-                }
-                if (ret == ERROR_SUCCESS) {
-                    assert(ulType == REG_SZ);
+                ret = WSAAddressToStringA(sockAddr,
+                          dnsServer->Address.iSockaddrLength, NULL,
+                          result, &dwLen);
+                if (ret == 0) {
                     strappend(ns, result);
                 }

-                /*
-                 * Finished with this registry key
-                 */
-                RegCloseKey(hKey);
+                dnsServer = dnsServer->Next;
             }

-            /*
-             * Onto the next adapeter
-             */
-            curr = curr->Next;
+            // Add connection-specific search domains in addition to
global one.
+            suffix = adapter->DnsSuffix;
+            if (suffix != NULL) {
+                ret = WideCharToMultiByte(CP_UTF8, 0, suffix, -1,
+                    result, sizeof(result), NULL, NULL);
+                if (ret != 0) {
+                    strappend(sl, result);
+                }
+            }
         }
-    }

-    /*
-     * Free the adpater structure
-     */
-    if (adapterP) {
-        free(adapterP);
+        adapter = adapter->Next;
     }

+    free(adapters);
+
     return STS_SL_FOUND & STS_NS_FOUND;
 }

@@ -260,7 +196,7 @@
Java_sun_net_dns_ResolverConfigurationImpl_loadDNSconfig0(JNIEnv *env,
jclass cl
     searchlist[0] = '\0';
     nameservers[0] = '\0';

-    if (loadConfig(searchlist, nameservers) != STS_ERROR) {
+    if (loadConfig(env, searchlist, nameservers) != STS_ERROR) {

         /*
          * Populate static fields in sun.net.DefaultResolverConfiguration

On Thu, Dec 12, 2019 at 1:49 AM Anuraag Agrawal <anuraaga at gmail.com> wrote:

> Hi Aleksei,
>
> Thanks for the feedback. I had thought about it but felt that it might be
> better to leave as much business logic to Java vs native as possible as a
> general principle. But if it makes more sense to do it native here happy to
> make the change :)
>
> Thanks,
> - Anuraag
>
> On Thu, Dec 12, 2019, 01:18 Aleks Efimov <aleksej.efimov at oracle.com>
> wrote:
>
>> Hi Anuraag,
>>
>> The webrev with the latest patch can be viewed here:
>> http://cr.openjdk.java.net/~aefimov/anuraaga/7006496/02
>>
>> Thanks for replacing FirstDnsSuffix usages with DnsSuffix. I've double
>> checked it with native application and can confirm that on my test host
>> (Microsoft Windows Server 2016 Standard) the DnsSuffix contains correct
>> information while the FirstDnsSuffix list is empty:
>>         DNS Suffix (From DnsSuffix field):  test.domain.com
>>         Number of IP Adapter DNS suffix entries: 0
>>
>>         DNS Suffix (From DnsSuffix field):
>>         Number of IP Adapter DNS suffix entries: 0
>>
>>         DNS Suffix (From DnsSuffix field):
>>         Number of IP Adapter DNS suffix entries: 0
>>
>>         DNS Suffix (From DnsSuffix field):
>>         Number of IP Adapter DNS suffix entries: 0
>>
>>         DNS Suffix (From DnsSuffix field):  test.domain.com
>>         Number of IP Adapter DNS suffix entries: 0
>>
>> About site-local addresses: Maybe we can move the site-local address
>> check to native code? i.e. analyze dnsServer->Address.lpSockaddr and filter
>> out site-local addresses.
>>
>> Testing:
>> Run your latest patch though our CI system -  no issues detected.
>>
>> -Aleksei
>>
>> On 10/12/2019 06:59, Anuraag Agrawal wrote:
>>
>> Hi Aleksei,
>>
>> Thanks for running the test. I had checked the global search list, but
>> realize I didn't check connection-specific suffixes which were causing the
>> issue you see. While the documentation states that FirstDnsSuffix is
>> populated on Vista+, amazingly it doesn't seem to be
>>
>>
>> https://docs.microsoft.com/en-us/windows/win32/api/iptypes/ns-iptypes-ip_adapter_addresses_lh
>>
>>
>> Chromium has run into the same issue and just doesn't use the field
>>
>>
>> https://cs.chromium.org/chromium/src/net/dns/dns_config_service_win.cc?q=firstdnssuffix&sq=package:chromium&dr=C&l=532
>>
>> So I have gone ahead and switched to using the normal DnsSuffix field.
>> DnsSuffix and looking up the search list in the registry should generally
>> give a full list.
>>
>> During this testing, other issues I found are that the search list
>> returns a comma-separated list. So to keep the string list parsing simple,
>> I changed the delimiter from space to comma. Also, on my machine I would
>> always have DNS servers like fec0:0:0:ffff:1 on some adapters. At first, I
>> assumed it is ok to return these, since they are configured by the OS and
>> should be valid, but I learnt that these are deprecated IPv6 site-local
>> addresses and should not be used.
>>
>> https://en.wikipedia.org/wiki/Unique_local_address
>>
>> I used the same check for site-local as Inet6Address, which just sees if
>> the first bytes are fec0.
>>
>> Thanks again - inline patch follows.
>>
>> diff --git
>> a/src/java.base/windows/classes/sun/net/dns/ResolverConfigurationImpl.java
>> b/src/java.base/windows/classes/sun/net/dns/ResolverConfigurationImpl.java
>> index 2250b3158e..b9a06461ab 100644
>> ---
>> a/src/java.base/windows/classes/sun/net/dns/ResolverConfigurationImpl.java
>> +++
>> b/src/java.base/windows/classes/sun/net/dns/ResolverConfigurationImpl.java
>> @@ -25,9 +25,9 @@
>>
>>  package sun.net.dns;
>>
>> +import java.util.ArrayList;
>>  import java.util.List;
>> -import java.util.LinkedList;
>> -import java.util.StringTokenizer;
>> +import java.util.concurrent.TimeUnit;
>>
>>  /*
>>   * An implementation of sun.net.ResolverConfiguration for Windows.
>> @@ -50,30 +50,65 @@ public class ResolverConfigurationImpl
>>
>>      // Cache timeout (120 seconds) - should be converted into property
>>      // or configured as preference in the future.
>> -    private static final int TIMEOUT = 120000;
>> +    private static final long TIMEOUT_NANOS =
>> TimeUnit.SECONDS.toNanos(120);
>>
>>      // DNS suffix list and name servers populated by native method
>>      private static String os_searchlist;
>>      private static String os_nameservers;
>>
>>      // Cached lists
>> -    private static LinkedList<String> searchlist;
>> -    private static LinkedList<String> nameservers;
>> -
>> -    // Parse string that consists of token delimited by space or commas
>> -    // and return LinkedHashMap
>> -    private LinkedList<String> stringToList(String str) {
>> -        LinkedList<String> ll = new LinkedList<>();
>> -
>> -        // comma and space are valid delimiters
>> -        StringTokenizer st = new StringTokenizer(str, ", ");
>> -        while (st.hasMoreTokens()) {
>> -            String s = st.nextToken();
>> -            if (!ll.contains(s)) {
>> -                ll.add(s);
>> +    private static ArrayList<String> searchlist;
>> +    private static ArrayList<String> nameservers;
>> +
>> +    // Parse string that consists of token delimited by comma
>> +    // and return ArrayList. Refer to ResolverConfigurationImpl.c and
>> +    // strappend to see how the string is created.
>> +    private ArrayList<String> stringToList(String str) {
>> +        // String is delimited by comma.
>> +        String[] tokens = str.split(",");
>> +        ArrayList<String> l = new ArrayList<>(tokens.length);
>> +        for (String s : tokens) {
>> +            if (!l.contains(s)) {
>> +                l.add(s);
>>              }
>>          }
>> -        return ll;
>> +        l.trimToSize();
>> +        return l;
>> +    }
>> +
>> +    // Parse string that consists of token delimited by comma
>> +    // and return ArrayList.  Refer to ResolverConfigurationImpl.c and
>> +    // strappend to see how the string is created.
>> +    // In addition to splitting the string, converts IPv6 addresses to
>> +    // BSD-style.
>> +    private ArrayList<String> addressesToList(String str) {
>> +        // String is delimited by comma
>> +        String[] tokens = str.split(",");
>> +        ArrayList<String> l = new ArrayList<>(tokens.length);
>> +
>> +        for (String s : tokens) {
>> +            if (!s.isEmpty()) {
>> +                if (s.indexOf(':') >= 0) {
>> +                    // IPv6
>> +                    if (s.charAt(0) != '[') {
>> +                        // Not BSD style
>> +                        s = '[' + s + ']';
>> +                    }
>> +                    if (s.startsWith("[fec0:")) {
>> +                        // Deprecated site-local address. Windows adds
>> +                        // such addresses to IPv6 adapters without DNS
>> +                        // configured, but these should not actually be
>> +                        // used for queries.
>> +                        continue;
>> +                    }
>> +                }
>> +                if (!l.contains(s)) {
>> +                    l.add(s);
>> +                }
>> +            }
>> +        }
>> +        l.trimToSize();
>> +        return l;
>>      }
>>
>>      // Load DNS configuration from OS
>> @@ -81,28 +116,34 @@ public class ResolverConfigurationImpl
>>      private void loadConfig() {
>>          assert Thread.holdsLock(lock);
>>
>> -        // if address have changed then DNS probably changed as well;
>> -        // otherwise check if cached settings have expired.
>> -        //
>> +        // A change in the network address of the machine usually
>> indicates
>> +        // a change in DNS configuration too so we always refresh the
>> config
>> +        // after such a change.
>>          if (changed) {
>>              changed = false;
>>          } else {
>> +            // Otherwise we refresh if TIMEOUT_NANOS has passed since
>> last
>> +            // load.
>>              if (lastRefresh >= 0) {
>> -                long currTime = System.currentTimeMillis();
>> -                if ((currTime - lastRefresh) < TIMEOUT) {
>> +                long currTime = System.nanoTime();
>> +                if ((currTime - lastRefresh) < TIMEOUT_NANOS) {
>>                      return;
>>                  }
>>              }
>>          }
>>
>> -        // load DNS configuration, update timestamp, create
>> -        // new HashMaps from the loaded configuration
>> -        //
>> +        // Native code that uses Windows API to find out the DNS server
>> +        // addresses and search suffixes. It builds a comma-delimited
>> string
>> +        // of nameservers and domain suffixes and sets them to the static
>> +        // os_nameservers and os_searchlist. We then split these into
>> Java
>> +        // Lists here.
>>          loadDNSconfig0();
>>
>> -        lastRefresh = System.currentTimeMillis();
>> +        // Record the time of update and refresh the lists of addresses /
>> +        // domain suffixes.
>> +        lastRefresh = System.nanoTime();
>>          searchlist = stringToList(os_searchlist);
>> -        nameservers = stringToList(os_nameservers);
>> +        nameservers = addressesToList(os_nameservers);
>>          os_searchlist = null;                       // can be GC'ed
>>          os_nameservers = null;
>>      }
>> diff --git a/src/java.base/windows/native/libnet/NetworkInterface_winXP.c
>> b/src/java.base/windows/native/libnet/NetworkInterface_winXP.c
>> index f2368bafcb..297a1561ef 100644
>> --- a/src/java.base/windows/native/libnet/NetworkInterface_winXP.c
>> +++ b/src/java.base/windows/native/libnet/NetworkInterface_winXP.c
>> @@ -73,8 +73,8 @@ const int MAX_TRIES = 3;
>>   * for each adapter on the system. Returned in *adapters.
>>   * Buffer is malloc'd and must be freed (unless error returned)
>>   */
>> -static int getAdapters (JNIEnv *env, IP_ADAPTER_ADDRESSES **adapters) {
>> -    DWORD ret, flags;
>> +int getAdapters (JNIEnv *env, int flags, IP_ADAPTER_ADDRESSES
>> **adapters) {
>> +    DWORD ret;
>>      IP_ADAPTER_ADDRESSES *adapterInfo;
>>      ULONG len;
>>      int try;
>> @@ -87,9 +87,6 @@ static int getAdapters (JNIEnv *env,
>> IP_ADAPTER_ADDRESSES **adapters) {
>>      }
>>
>>      len = BUFF_SIZE;
>> -    flags = GAA_FLAG_SKIP_DNS_SERVER;
>> -    flags |= GAA_FLAG_SKIP_MULTICAST;
>> -    flags |= GAA_FLAG_INCLUDE_PREFIX;
>>      ret = GetAdaptersAddresses(AF_UNSPEC, flags, NULL, adapterInfo,
>> &len);
>>
>>      for (try = 0; ret == ERROR_BUFFER_OVERFLOW && try < MAX_TRIES;
>> ++try) {
>> @@ -240,7 +237,7 @@ static int ipinflen = 2048;
>>   */
>>  int getAllInterfacesAndAddresses (JNIEnv *env, netif **netifPP)
>>  {
>> -    DWORD ret;
>> +    DWORD ret, flags;
>>      MIB_IPADDRTABLE *tableP;
>>      IP_ADAPTER_ADDRESSES *ptr, *adapters=NULL;
>>      ULONG len=ipinflen, count=0;
>> @@ -296,7 +293,11 @@ int getAllInterfacesAndAddresses (JNIEnv *env, netif
>> **netifPP)
>>          }
>>      }
>>      free(tableP);
>> -    ret = getAdapters (env, &adapters);
>> +
>> +    flags = GAA_FLAG_SKIP_DNS_SERVER;
>> +    flags |= GAA_FLAG_SKIP_MULTICAST;
>> +    flags |= GAA_FLAG_INCLUDE_PREFIX;
>> +    ret = getAdapters (env, flags, &adapters);
>>      if (ret != ERROR_SUCCESS) {
>>          goto err;
>>      }
>> diff --git
>> a/src/java.base/windows/native/libnet/ResolverConfigurationImpl.c
>> b/src/java.base/windows/native/libnet/ResolverConfigurationImpl.c
>> index 13b28044a5..427d7c85eb 100644
>> --- a/src/java.base/windows/native/libnet/ResolverConfigurationImpl.c
>> +++ b/src/java.base/windows/native/libnet/ResolverConfigurationImpl.c
>> @@ -1,5 +1,5 @@
>>  /*
>> - * Copyright (c) 2002, 2013, Oracle and/or its affiliates. All rights
>> reserved.
>> + * Copyright (c) 2002, 2019, 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
>> @@ -30,6 +30,7 @@
>>  #include <iprtrmib.h>
>>  #include <time.h>
>>  #include <assert.h>
>> +#include <winsock2.h>
>>  #include <iphlpapi.h>
>>
>>  #include "jni_util.h"
>> @@ -48,8 +49,10 @@
>>  static jfieldID searchlistID;
>>  static jfieldID nameserversID;
>>
>> +extern int getAdapters(JNIEnv *env, int flags, IP_ADAPTER_ADDRESSES
>> **adapters);
>> +
>>  /*
>> - * Utility routine to append s2 to s1 with a space delimiter.
>> + * Utility routine to append s2 to s1 with a comma delimiter.
>>   *  strappend(s1="abc", "def")  => "abc def"
>>   *  strappend(s1="", "def")     => "def
>>   */
>> @@ -60,41 +63,30 @@ void strappend(char *s1, char *s2) {
>>          return;
>>
>>      len = strlen(s1)+1;
>> -    if (s1[0] != 0)                         /* needs space character */
>> +    if (s1[0] != 0)                         /* needs comma character */
>>          len++;
>>      if (len + strlen(s2) > MAX_STR_LEN)     /* insufficient space */
>>          return;
>>
>>      if (s1[0] != 0) {
>> -        strcat(s1, " ");
>> +        strcat(s1, ",");
>>      }
>>      strcat(s1, s2);
>>  }
>>
>>  /*
>> - * Windows 2000/XP
>> - *
>> - * Use registry approach based on settings described in Appendix C
>> - * of "Microsoft Windows 2000 TCP/IP Implementation Details".
>> - *
>> - * DNS suffix list is obtained from SearchList registry setting. If
>> - * this is not specified we compile suffix list based on the
>> - * per-connection domain suffix.
>> - *
>> - * DNS name servers and domain settings are on a per-connection
>> - * basic. We therefore enumerate the network adapters to get the
>> - * names of each adapter and then query the corresponding registry
>> - * settings to obtain NameServer/DhcpNameServer and Domain/DhcpDomain.
>> + * Use DNS server addresses returned by GetAdaptersAddresses for
>> currently
>> + * active interfaces.
>>   */
>> -static int loadConfig(char *sl, char *ns) {
>> -    IP_ADAPTER_INFO *adapterP;
>> -    ULONG size;
>> -    DWORD ret;
>> +static int loadConfig(JNIEnv *env, char *sl, char *ns) {
>> +    IP_ADAPTER_ADDRESSES *adapters, *adapter;
>> +    IP_ADAPTER_DNS_SERVER_ADDRESS *dnsServer;
>> +    WCHAR *suffix;
>> +    DWORD ret, flags;
>>      DWORD dwLen;
>>      ULONG ulType;
>>      char result[MAX_STR_LEN];
>>      HANDLE hKey;
>> -    int gotSearchList = 0;
>>
>>      /*
>>       * First see if there is a global suffix list specified.
>> @@ -112,122 +104,55 @@ static int loadConfig(char *sl, char *ns) {
>>              assert(ulType == REG_SZ);
>>              if (strlen(result) > 0) {
>>                  strappend(sl, result);
>> -                gotSearchList = 1;
>>              }
>>          }
>>          RegCloseKey(hKey);
>>      }
>>
>> -    /*
>> -     * Ask the IP Helper library to enumerate the adapters
>> -     */
>> -    size = sizeof(IP_ADAPTER_INFO);
>> -    adapterP = (IP_ADAPTER_INFO *)malloc(size);
>> -    if (adapterP == NULL) {
>> -        return STS_ERROR;
>> -    }
>> -    ret = GetAdaptersInfo(adapterP, &size);
>> -    if (ret == ERROR_BUFFER_OVERFLOW) {
>> -        IP_ADAPTER_INFO *newAdapterP = (IP_ADAPTER_INFO
>> *)realloc(adapterP, size);
>> -        if (newAdapterP == NULL) {
>> -            free(adapterP);
>> -            return STS_ERROR;
>> -        }
>> -        adapterP = newAdapterP;
>>
>> -        ret = GetAdaptersInfo(adapterP, &size);
>> +    // We only need DNS server addresses so skip everything else.
>> +    flags = GAA_FLAG_SKIP_UNICAST;
>> +    flags |= GAA_FLAG_SKIP_ANYCAST;
>> +    flags |= GAA_FLAG_SKIP_MULTICAST;
>> +    flags |= GAA_FLAG_SKIP_FRIENDLY_NAME;
>> +    ret = getAdapters(env, flags, &adapters);
>> +    if (ret != ERROR_SUCCESS) {
>> +        return STS_ERROR;
>>      }
>>
>> -    /*
>> -     * Iterate through the list of adapters as registry settings are
>> -     * keyed on the adapter name (GUID).
>> -     */
>> -    if (ret == ERROR_SUCCESS) {
>> -        IP_ADAPTER_INFO *curr = adapterP;
>> -        while (curr != NULL) {
>> -            char key[MAX_STR_LEN];
>> -
>> -            sprintf(key,
>> -
>>  "SYSTEM\\CurrentControlSet\\Services\\Tcpip\\Parameters\\Interfaces\\%s",
>> -                curr->AdapterName);
>> -
>> -            ret = RegOpenKeyEx(HKEY_LOCAL_MACHINE,
>> -                               key,
>> -                               0,
>> -                               KEY_READ,
>> -                               (PHKEY)&hKey);
>> -            if (ret == ERROR_SUCCESS) {
>> -                DWORD enableDhcp = 0;
>> -
>> -                /*
>> -                 * Is DHCP enabled on this interface
>> -                 */
>> -                dwLen = sizeof(enableDhcp);
>> -                ret = RegQueryValueEx(hKey, "EnableDhcp", NULL, &ulType,
>> -                                     (LPBYTE)&enableDhcp, &dwLen);
>> -
>> -                /*
>> -                 * If we don't have the suffix list when get the Domain
>> -                 * or DhcpDomain. If DHCP is enabled then Domain overides
>> -                 * DhcpDomain
>> -                 */
>> -                if (!gotSearchList) {
>> -                    result[0] = '\0';
>> -                    dwLen = sizeof(result);
>> -                    ret = RegQueryValueEx(hKey, "Domain", NULL, &ulType,
>> -                                         (LPBYTE)&result, &dwLen);
>> -                    if (((ret != ERROR_SUCCESS) || (strlen(result) ==
>> 0)) &&
>> -                        enableDhcp) {
>> -                        dwLen = sizeof(result);
>> -                        ret = RegQueryValueEx(hKey, "DhcpDomain", NULL,
>> &ulType,
>> -                                              (LPBYTE)&result, &dwLen);
>> -                    }
>> -                    if (ret == ERROR_SUCCESS) {
>> -                        assert(ulType == REG_SZ);
>> -                        strappend(sl, result);
>> -                    }
>> -                }
>> -
>> -                /*
>> -                 * Get DNS servers based on NameServer or DhcpNameServer
>> -                 * registry setting. If NameServer is set then it
>> overrides
>> -                 * DhcpNameServer (even if DHCP is enabled).
>> -                 */
>> -                result[0] = '\0';
>> +    adapter = adapters;
>> +    while (adapter != NULL) {
>> +        // Only load config from enabled adapters.
>> +        if (adapter->OperStatus == IfOperStatusUp) {
>> +            dnsServer = adapter->FirstDnsServerAddress;
>> +            while (dnsServer != NULL) {
>>                  dwLen = sizeof(result);
>> -                ret = RegQueryValueEx(hKey, "NameServer", NULL, &ulType,
>> -                                     (LPBYTE)&result, &dwLen);
>> -                if (((ret != ERROR_SUCCESS) || (strlen(result) == 0)) &&
>> -                    enableDhcp) {
>> -                    dwLen = sizeof(result);
>> -                    ret = RegQueryValueEx(hKey, "DhcpNameServer", NULL,
>> &ulType,
>> -                                          (LPBYTE)&result, &dwLen);
>> -                }
>> -                if (ret == ERROR_SUCCESS) {
>> -                    assert(ulType == REG_SZ);
>> +                ret = WSAAddressToStringA(dnsServer->Address.lpSockaddr,
>> +                          dnsServer->Address.iSockaddrLength, NULL,
>> +                          result, &dwLen);
>> +                if (ret == 0) {
>>                      strappend(ns, result);
>>                  }
>>
>> -                /*
>> -                 * Finished with this registry key
>> -                 */
>> -                RegCloseKey(hKey);
>> +                dnsServer = dnsServer->Next;
>>              }
>>
>> -            /*
>> -             * Onto the next adapeter
>> -             */
>> -            curr = curr->Next;
>> +            // Add connection-specific search domains in addition to
>> global one.
>> +            suffix = adapter->DnsSuffix;
>> +            if (suffix != NULL) {
>> +                ret = WideCharToMultiByte(CP_UTF8, 0, suffix, -1,
>> +                    result, sizeof(result), NULL, NULL);
>> +                if (ret != 0) {
>> +                    strappend(sl, result);
>> +                }
>> +            }
>>          }
>> -    }
>>
>> -    /*
>> -     * Free the adpater structure
>> -     */
>> -    if (adapterP) {
>> -        free(adapterP);
>> +        adapter = adapter->Next;
>>      }
>>
>> +    free(adapters);
>> +
>>      return STS_SL_FOUND & STS_NS_FOUND;
>>  }
>>
>> @@ -260,7 +185,7 @@
>> Java_sun_net_dns_ResolverConfigurationImpl_loadDNSconfig0(JNIEnv *env,
>> jclass cl
>>      searchlist[0] = '\0';
>>      nameservers[0] = '\0';
>>
>> -    if (loadConfig(searchlist, nameservers) != STS_ERROR) {
>> +    if (loadConfig(env, searchlist, nameservers) != STS_ERROR) {
>>
>>          /*
>>           * Populate static fields in sun.net.DefaultResolverConfiguration
>>
>> On Tue, Dec 10, 2019 at 1:29 AM Aleks Efimov <aleksej.efimov at oracle.com>
>> wrote:
>>
>>> Hi Anuraag,
>>>
>>> The webrev with your latest changes can be found here:
>>>     http://cr.openjdk.java.net/~aefimov/anuraaga/7006496/01
>>>
>>> The copyright changes looks good.
>>>
>>> The split by space also looks good with assumption that we will never
>>> get string with two spaces between IP addresses/DNS suffixes.
>>>
>>> I've also performed one test on Windows machine and it shows an issue
>>> with the retrieval of DNS suffixes:
>>> Method to call:
>>>      sun.net.dns.ResolverConfiguration.open().searchlist()
>>>
>>> Old implementation returns:
>>>     [test.domain.com]
>>>
>>> With the latest patch the suffixes list (searchlist) is empty:
>>>     []
>>>
>>> I've collected the following information on the test host that might
>>> help you to fix the issue:
>>>
>>> The host OS: Microsoft Windows Server 2016 Standard
>>>
>>> Networking configuration (<---> is for masked addresses/info):
>>> $ ipconfig /all
>>>
>>> Windows IP Configuration
>>>
>>>    Host Name . . . . . . . . . . . . : host-name-1
>>>    Primary Dns Suffix  . . . . . . . :
>>>    Node Type . . . . . . . . . . . . : Hybrid
>>>    IP Routing Enabled. . . . . . . . : No
>>>    WINS Proxy Enabled. . . . . . . . : No
>>>    DNS Suffix Search List. . . . . . : test.domain.com
>>>
>>> Ethernet adapter Ethernet:
>>>
>>>    Connection-specific DNS Suffix  . : test.domain.com
>>>    Description . . . . . . . . . . . : Broadcom NetXtreme-E Virtual
>>> Function
>>>    Physical Address. . . . . . . . . : <------------>
>>>    DHCP Enabled. . . . . . . . . . . : Yes
>>>    Autoconfiguration Enabled . . . . : Yes
>>>    Link-local IPv6 Address . . . . . : <------------>
>>>    IPv4 Address. . . . . . . . . . . : <------------>
>>>    Subnet Mask . . . . . . . . . . . : <------------>
>>>    Lease Obtained. . . . . . . . . . : <------------>
>>>    Lease Expires . . . . . . . . . . : <------------>
>>>    Default Gateway . . . . . . . . . : <------------>
>>>    DHCP Server . . . . . . . . . . . : <------------>
>>>    DHCPv6 Client DUID. . . . . . . . : <------------>
>>>    DNS Servers . . . . . . . . . . . : <------------>
>>>                                        <------------>
>>>    NetBIOS over Tcpip. . . . . . . . : Disabled
>>>
>>> Tunnel adapter isatap.test.domain.com:
>>>
>>>    Media State . . . . . . . . . . . : Media disconnected
>>>    Connection-specific DNS Suffix  . : test.domain.com
>>>    Description . . . . . . . . . . . : Microsoft ISATAP Adapter #3
>>>    Physical Address. . . . . . . . . : <------------>
>>>    DHCP Enabled. . . . . . . . . . . : No
>>>    Autoconfiguration Enabled . . . . : Yes
>>>
>>>
>>> - Aleksei
>>>
>>>
>>> On 07/12/2019 09:44, Anuraag Agrawal wrote:
>>>
>>> Hi all,
>>>
>>> Thanks for the reviews. I've fixed the formatting errors, and I hope I
>>> fixed the copyright issue. I couldn't find documentation on the format of
>>> the copyright header, but assume the second number is the year of
>>> modification to update. I found ResolverConfigurationImpl.c to have an old
>>> one and updated it to 2019.
>>>
>>> I also found the note in the docs that StringTokenizer is deprecated and
>>> shouldn't be used - I agree it's a good time to replace it. As we have a
>>> simple split by space, I have gone ahead and used the simpler String.split
>>> instead of regex, hope that makes sense. While in many code I'd be a little
>>> concerned with the array allocation, this is only run very infrequently so
>>> I think it should be ok.
>>>
>>> Inline diff follows
>>>
>>> diff --git
>>> a/src/java.base/windows/classes/sun/net/dns/ResolverConfigurationImpl.java
>>> b/src/java.base/windows/classes/sun/net/dns/ResolverConfigurationImpl.java
>>> index 2250b3158e..47065e805e 100644
>>> ---
>>> a/src/java.base/windows/classes/sun/net/dns/ResolverConfigurationImpl.java
>>> +++
>>> b/src/java.base/windows/classes/sun/net/dns/ResolverConfigurationImpl.java
>>> @@ -25,9 +25,9 @@
>>>
>>>  package sun.net.dns;
>>>
>>> +import java.util.ArrayList;
>>>  import java.util.List;
>>> -import java.util.LinkedList;
>>> -import java.util.StringTokenizer;
>>> +import java.util.concurrent.TimeUnit;
>>>
>>>  /*
>>>   * An implementation of sun.net.ResolverConfiguration for Windows.
>>> @@ -50,30 +50,55 @@ public class ResolverConfigurationImpl
>>>
>>>      // Cache timeout (120 seconds) - should be converted into property
>>>      // or configured as preference in the future.
>>> -    private static final int TIMEOUT = 120000;
>>> +    private static final long TIMEOUT_NANOS =
>>> TimeUnit.SECONDS.toNanos(120);
>>>
>>>      // DNS suffix list and name servers populated by native method
>>>      private static String os_searchlist;
>>>      private static String os_nameservers;
>>>
>>>      // Cached lists
>>> -    private static LinkedList<String> searchlist;
>>> -    private static LinkedList<String> nameservers;
>>> -
>>> -    // Parse string that consists of token delimited by space or commas
>>> -    // and return LinkedHashMap
>>> -    private LinkedList<String> stringToList(String str) {
>>> -        LinkedList<String> ll = new LinkedList<>();
>>> -
>>> -        // comma and space are valid delimiters
>>> -        StringTokenizer st = new StringTokenizer(str, ", ");
>>> -        while (st.hasMoreTokens()) {
>>> -            String s = st.nextToken();
>>> -            if (!ll.contains(s)) {
>>> -                ll.add(s);
>>> +    private static ArrayList<String> searchlist;
>>> +    private static ArrayList<String> nameservers;
>>> +
>>> +    // Parse string that consists of token delimited by space
>>> +    // and return ArrayList. Refer to ResolverConfigurationImpl.c and
>>> +    // strappend to see how the string is created.
>>> +    private ArrayList<String> stringToList(String str) {
>>> +        // String is delimited by space.
>>> +        String[] tokens = str.split(" ");
>>> +        ArrayList<String> l = new ArrayList<>(tokens.length);
>>> +        for (String s : tokens) {
>>> +            if (!l.contains(s)) {
>>> +                l.add(s);
>>>              }
>>>          }
>>> -        return ll;
>>> +        l.trimToSize();
>>> +        return l;
>>> +    }
>>> +
>>> +    // Parse string that consists of token delimited by space
>>> +    // and return ArrayList.  Refer to ResolverConfigurationImpl.c and
>>> +    // strappend to see how the string is created.
>>> +    // In addition to splitting the string, converts IPv6 addresses to
>>> +    // BSD-style.
>>> +    private ArrayList<String> addressesToList(String str) {
>>> +        // String is delimited by space
>>> +        String[] tokens = str.split(" ");
>>> +        ArrayList<String> l = new ArrayList<>(tokens.length);
>>> +
>>> +        for (String s : tokens) {
>>> +            if (!s.isEmpty()) {
>>> +                if (s.indexOf(':') >= 0 && s.charAt(0) != '[') {
>>> +                    // Not BSD style
>>> +                    s = '[' + s + ']';
>>> +                }
>>> +                if (!l.contains(s)) {
>>> +                    l.add(s);
>>> +                }
>>> +            }
>>> +        }
>>> +        l.trimToSize();
>>> +        return l;
>>>      }
>>>
>>>      // Load DNS configuration from OS
>>> @@ -81,28 +106,34 @@ public class ResolverConfigurationImpl
>>>      private void loadConfig() {
>>>          assert Thread.holdsLock(lock);
>>>
>>> -        // if address have changed then DNS probably changed as well;
>>> -        // otherwise check if cached settings have expired.
>>> -        //
>>> +        // A change in the network address of the machine usually
>>> indicates
>>> +        // a change in DNS configuration too so we always refresh the
>>> config
>>> +        // after such a change.
>>>          if (changed) {
>>>              changed = false;
>>>          } else {
>>> +            // Otherwise we refresh if TIMEOUT_NANOS has passed since
>>> last
>>> +            // load.
>>>              if (lastRefresh >= 0) {
>>> -                long currTime = System.currentTimeMillis();
>>> -                if ((currTime - lastRefresh) < TIMEOUT) {
>>> +                long currTime = System.nanoTime();
>>> +                if ((currTime - lastRefresh) < TIMEOUT_NANOS) {
>>>                      return;
>>>                  }
>>>              }
>>>          }
>>>
>>> -        // load DNS configuration, update timestamp, create
>>> -        // new HashMaps from the loaded configuration
>>> -        //
>>> +        // Native code that uses Windows API to find out the DNS server
>>> +        // addresses and search suffixes. It builds a space-delimited
>>> string
>>> +        // of nameservers and domain suffixes and sets them to the
>>> static
>>> +        // os_nameservers and os_searchlist. We then split these into
>>> Java
>>> +        // Lists here.
>>>          loadDNSconfig0();
>>>
>>> -        lastRefresh = System.currentTimeMillis();
>>> +        // Record the time of update and refresh the lists of addresses
>>> /
>>> +        // domain suffixes.
>>> +        lastRefresh = System.nanoTime();
>>>          searchlist = stringToList(os_searchlist);
>>> -        nameservers = stringToList(os_nameservers);
>>> +        nameservers = addressesToList(os_nameservers);
>>>          os_searchlist = null;                       // can be GC'ed
>>>          os_nameservers = null;
>>>      }
>>> diff --git
>>> a/src/java.base/windows/native/libnet/NetworkInterface_winXP.c
>>> b/src/java.base/windows/native/libnet/NetworkInterface_winXP.c
>>> index f2368bafcb..297a1561ef 100644
>>> --- a/src/java.base/windows/native/libnet/NetworkInterface_winXP.c
>>> +++ b/src/java.base/windows/native/libnet/NetworkInterface_winXP.c
>>> @@ -73,8 +73,8 @@ const int MAX_TRIES = 3;
>>>   * for each adapter on the system. Returned in *adapters.
>>>   * Buffer is malloc'd and must be freed (unless error returned)
>>>   */
>>> -static int getAdapters (JNIEnv *env, IP_ADAPTER_ADDRESSES **adapters) {
>>> -    DWORD ret, flags;
>>> +int getAdapters (JNIEnv *env, int flags, IP_ADAPTER_ADDRESSES
>>> **adapters) {
>>> +    DWORD ret;
>>>      IP_ADAPTER_ADDRESSES *adapterInfo;
>>>      ULONG len;
>>>      int try;
>>> @@ -87,9 +87,6 @@ static int getAdapters (JNIEnv *env,
>>> IP_ADAPTER_ADDRESSES **adapters) {
>>>      }
>>>
>>>      len = BUFF_SIZE;
>>> -    flags = GAA_FLAG_SKIP_DNS_SERVER;
>>> -    flags |= GAA_FLAG_SKIP_MULTICAST;
>>> -    flags |= GAA_FLAG_INCLUDE_PREFIX;
>>>      ret = GetAdaptersAddresses(AF_UNSPEC, flags, NULL, adapterInfo,
>>> &len);
>>>
>>>      for (try = 0; ret == ERROR_BUFFER_OVERFLOW && try < MAX_TRIES;
>>> ++try) {
>>> @@ -240,7 +237,7 @@ static int ipinflen = 2048;
>>>   */
>>>  int getAllInterfacesAndAddresses (JNIEnv *env, netif **netifPP)
>>>  {
>>> -    DWORD ret;
>>> +    DWORD ret, flags;
>>>      MIB_IPADDRTABLE *tableP;
>>>      IP_ADAPTER_ADDRESSES *ptr, *adapters=NULL;
>>>      ULONG len=ipinflen, count=0;
>>> @@ -296,7 +293,11 @@ int getAllInterfacesAndAddresses (JNIEnv *env,
>>> netif **netifPP)
>>>          }
>>>      }
>>>      free(tableP);
>>> -    ret = getAdapters (env, &adapters);
>>> +
>>> +    flags = GAA_FLAG_SKIP_DNS_SERVER;
>>> +    flags |= GAA_FLAG_SKIP_MULTICAST;
>>> +    flags |= GAA_FLAG_INCLUDE_PREFIX;
>>> +    ret = getAdapters (env, flags, &adapters);
>>>      if (ret != ERROR_SUCCESS) {
>>>          goto err;
>>>      }
>>> diff --git
>>> a/src/java.base/windows/native/libnet/ResolverConfigurationImpl.c
>>> b/src/java.base/windows/native/libnet/ResolverConfigurationImpl.c
>>> index 13b28044a5..85a7935314 100644
>>> --- a/src/java.base/windows/native/libnet/ResolverConfigurationImpl.c
>>> +++ b/src/java.base/windows/native/libnet/ResolverConfigurationImpl.c
>>> @@ -1,5 +1,5 @@
>>>  /*
>>> - * Copyright (c) 2002, 2013, Oracle and/or its affiliates. All rights
>>> reserved.
>>> + * Copyright (c) 2002, 2019, 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
>>> @@ -30,6 +30,7 @@
>>>  #include <iprtrmib.h>
>>>  #include <time.h>
>>>  #include <assert.h>
>>> +#include <winsock2.h>
>>>  #include <iphlpapi.h>
>>>
>>>  #include "jni_util.h"
>>> @@ -48,6 +49,8 @@
>>>  static jfieldID searchlistID;
>>>  static jfieldID nameserversID;
>>>
>>> +extern int getAdapters(JNIEnv *env, int flags, IP_ADAPTER_ADDRESSES
>>> **adapters);
>>> +
>>>  /*
>>>   * Utility routine to append s2 to s1 with a space delimiter.
>>>   *  strappend(s1="abc", "def")  => "abc def"
>>> @@ -72,29 +75,19 @@ void strappend(char *s1, char *s2) {
>>>  }
>>>
>>>  /*
>>> - * Windows 2000/XP
>>> - *
>>> - * Use registry approach based on settings described in Appendix C
>>> - * of "Microsoft Windows 2000 TCP/IP Implementation Details".
>>> - *
>>> - * DNS suffix list is obtained from SearchList registry setting. If
>>> - * this is not specified we compile suffix list based on the
>>> - * per-connection domain suffix.
>>> - *
>>> - * DNS name servers and domain settings are on a per-connection
>>> - * basic. We therefore enumerate the network adapters to get the
>>> - * names of each adapter and then query the corresponding registry
>>> - * settings to obtain NameServer/DhcpNameServer and Domain/DhcpDomain.
>>> + * Use DNS server addresses returned by GetAdaptersAddresses for
>>> currently
>>> + * active interfaces.
>>>   */
>>> -static int loadConfig(char *sl, char *ns) {
>>> -    IP_ADAPTER_INFO *adapterP;
>>> -    ULONG size;
>>> -    DWORD ret;
>>> +static int loadConfig(JNIEnv *env, char *sl, char *ns) {
>>> +    IP_ADAPTER_ADDRESSES *adapters, *adapter;
>>> +    IP_ADAPTER_DNS_SERVER_ADDRESS *dnsServer;
>>> +    SOCKADDR *address;
>>> +    IP_ADAPTER_DNS_SUFFIX *suffix;
>>> +    DWORD ret, flags;
>>>      DWORD dwLen;
>>>      ULONG ulType;
>>>      char result[MAX_STR_LEN];
>>>      HANDLE hKey;
>>> -    int gotSearchList = 0;
>>>
>>>      /*
>>>       * First see if there is a global suffix list specified.
>>> @@ -112,122 +105,58 @@ static int loadConfig(char *sl, char *ns) {
>>>              assert(ulType == REG_SZ);
>>>              if (strlen(result) > 0) {
>>>                  strappend(sl, result);
>>> -                gotSearchList = 1;
>>>              }
>>>          }
>>>          RegCloseKey(hKey);
>>>      }
>>>
>>> -    /*
>>> -     * Ask the IP Helper library to enumerate the adapters
>>> -     */
>>> -    size = sizeof(IP_ADAPTER_INFO);
>>> -    adapterP = (IP_ADAPTER_INFO *)malloc(size);
>>> -    if (adapterP == NULL) {
>>> -        return STS_ERROR;
>>> -    }
>>> -    ret = GetAdaptersInfo(adapterP, &size);
>>> -    if (ret == ERROR_BUFFER_OVERFLOW) {
>>> -        IP_ADAPTER_INFO *newAdapterP = (IP_ADAPTER_INFO
>>> *)realloc(adapterP, size);
>>> -        if (newAdapterP == NULL) {
>>> -            free(adapterP);
>>> -            return STS_ERROR;
>>> -        }
>>> -        adapterP = newAdapterP;
>>>
>>> -        ret = GetAdaptersInfo(adapterP, &size);
>>> +    // We only need DNS server addresses so skip everything else.
>>> +    flags = GAA_FLAG_SKIP_UNICAST;
>>> +    flags |= GAA_FLAG_SKIP_ANYCAST;
>>> +    flags |= GAA_FLAG_SKIP_MULTICAST;
>>> +    flags |= GAA_FLAG_SKIP_FRIENDLY_NAME;
>>> +    ret = getAdapters(env, flags, &adapters);
>>> +    if (ret != ERROR_SUCCESS) {
>>> +        return STS_ERROR;
>>>      }
>>>
>>> -    /*
>>> -     * Iterate through the list of adapters as registry settings are
>>> -     * keyed on the adapter name (GUID).
>>> -     */
>>> -    if (ret == ERROR_SUCCESS) {
>>> -        IP_ADAPTER_INFO *curr = adapterP;
>>> -        while (curr != NULL) {
>>> -            char key[MAX_STR_LEN];
>>> -
>>> -            sprintf(key,
>>> -
>>>  "SYSTEM\\CurrentControlSet\\Services\\Tcpip\\Parameters\\Interfaces\\%s",
>>> -                curr->AdapterName);
>>> -
>>> -            ret = RegOpenKeyEx(HKEY_LOCAL_MACHINE,
>>> -                               key,
>>> -                               0,
>>> -                               KEY_READ,
>>> -                               (PHKEY)&hKey);
>>> -            if (ret == ERROR_SUCCESS) {
>>> -                DWORD enableDhcp = 0;
>>> -
>>> -                /*
>>> -                 * Is DHCP enabled on this interface
>>> -                 */
>>> -                dwLen = sizeof(enableDhcp);
>>> -                ret = RegQueryValueEx(hKey, "EnableDhcp", NULL, &ulType,
>>> -                                     (LPBYTE)&enableDhcp, &dwLen);
>>> -
>>> -                /*
>>> -                 * If we don't have the suffix list when get the Domain
>>> -                 * or DhcpDomain. If DHCP is enabled then Domain
>>> overides
>>> -                 * DhcpDomain
>>> -                 */
>>> -                if (!gotSearchList) {
>>> -                    result[0] = '\0';
>>> -                    dwLen = sizeof(result);
>>> -                    ret = RegQueryValueEx(hKey, "Domain", NULL, &ulType,
>>> -                                         (LPBYTE)&result, &dwLen);
>>> -                    if (((ret != ERROR_SUCCESS) || (strlen(result) ==
>>> 0)) &&
>>> -                        enableDhcp) {
>>> -                        dwLen = sizeof(result);
>>> -                        ret = RegQueryValueEx(hKey, "DhcpDomain", NULL,
>>> &ulType,
>>> -                                              (LPBYTE)&result, &dwLen);
>>> -                    }
>>> -                    if (ret == ERROR_SUCCESS) {
>>> -                        assert(ulType == REG_SZ);
>>> -                        strappend(sl, result);
>>> -                    }
>>> -                }
>>> -
>>> -                /*
>>> -                 * Get DNS servers based on NameServer or DhcpNameServer
>>> -                 * registry setting. If NameServer is set then it
>>> overrides
>>> -                 * DhcpNameServer (even if DHCP is enabled).
>>> -                 */
>>> -                result[0] = '\0';
>>> +    adapter = adapters;
>>> +    while (adapter != NULL) {
>>> +        // Only load config from enabled adapters.
>>> +        if (adapter->OperStatus == IfOperStatusUp) {
>>> +            dnsServer = adapter->FirstDnsServerAddress;
>>> +            while (dnsServer != NULL) {
>>> +                address = dnsServer->Address.lpSockaddr;
>>>                  dwLen = sizeof(result);
>>> -                ret = RegQueryValueEx(hKey, "NameServer", NULL, &ulType,
>>> -                                     (LPBYTE)&result, &dwLen);
>>> -                if (((ret != ERROR_SUCCESS) || (strlen(result) == 0)) &&
>>> -                    enableDhcp) {
>>> -                    dwLen = sizeof(result);
>>> -                    ret = RegQueryValueEx(hKey, "DhcpNameServer", NULL,
>>> &ulType,
>>> -                                          (LPBYTE)&result, &dwLen);
>>> -                }
>>> -                if (ret == ERROR_SUCCESS) {
>>> -                    assert(ulType == REG_SZ);
>>> +                ret = WSAAddressToStringA(dnsServer->Address.lpSockaddr,
>>> +                          dnsServer->Address.iSockaddrLength, NULL,
>>> +                          result, &dwLen);
>>> +                if (ret == 0) {
>>>                      strappend(ns, result);
>>>                  }
>>>
>>> -                /*
>>> -                 * Finished with this registry key
>>> -                 */
>>> -                RegCloseKey(hKey);
>>> +                dnsServer = dnsServer->Next;
>>>              }
>>>
>>> -            /*
>>> -             * Onto the next adapeter
>>> -             */
>>> -            curr = curr->Next;
>>> +            // Add connection-specific search domains in addition to
>>> global one.
>>> +            suffix = adapter->FirstDnsSuffix;
>>> +            while (suffix != NULL) {
>>> +                ret = WideCharToMultiByte(CP_UTF8, 0, suffix->String,
>>> -1,
>>> +                    result, sizeof(result), NULL, NULL);
>>> +                if (ret != 0) {
>>> +                    strappend(sl, result);
>>> +                }
>>> +
>>> +                suffix = suffix->Next;
>>> +            }
>>>          }
>>> -    }
>>>
>>> -    /*
>>> -     * Free the adpater structure
>>> -     */
>>> -    if (adapterP) {
>>> -        free(adapterP);
>>> +        adapter = adapter->Next;
>>>      }
>>>
>>> +    free(adapters);
>>> +
>>>      return STS_SL_FOUND & STS_NS_FOUND;
>>>  }
>>>
>>> @@ -260,7 +189,7 @@
>>> Java_sun_net_dns_ResolverConfigurationImpl_loadDNSconfig0(JNIEnv *env,
>>> jclass cl
>>>      searchlist[0] = '\0';
>>>      nameservers[0] = '\0';
>>>
>>> -    if (loadConfig(searchlist, nameservers) != STS_ERROR) {
>>> +    if (loadConfig(env, searchlist, nameservers) != STS_ERROR) {
>>>
>>>          /*
>>>           * Populate static fields in
>>> sun.net.DefaultResolverConfiguration
>>>
>>> On Sat, Dec 7, 2019 at 12:41 AM Alan Bateman <Alan.Bateman at oracle.com>
>>> wrote:
>>>
>>>> On 06/12/2019 15:34, Aleks Efimov wrote:
>>>> > :
>>>> >
>>>> > I've created webrev with your latest changes - it could be convenient
>>>> > for other reviewers:
>>>> > http://cr.openjdk.java.net/~aefimov/anuraaga/7006496/00
>>>> >
>>>> > I will happily sponsor this change once it gets necessary approvals
>>>> This could be split into two issues but since the code using
>>>> StringTokenizer is changing significantly then we should replace it
>>>> with
>>>> regex while we there.
>>>>
>>>> -Alan
>>>>
>>>
>>>
>>
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