[PATCH] 7006496: Use modern Windows API to retrieve OS DNS servers
Aleks Efimov
aleksej.efimov at oracle.com
Wed Dec 4 15:56:06 UTC 2019
Hi Anuraag,
I've run your latest patch via our CI system and the results are good
One comment about the code changes:
I'm not sure that we need to pre-calculate the array list size since we
can get the same name server address multiple times and we will ignore
the duplicates later ('l.contains(s)' check). The default ArrayList
constructor (10 elements size) and the 'ArrayList::trimToSize' could be
used.
Or maybe combine both approaches (pre-calculate + resize):
Use 'StringTokenizer::countTokens' (replacement for
'allocateListForDelimitedString' method that can be deleted) for initial
size calculation and after processing tokens call
'ArrayList::trimToSize'. For cases with no duplicates (more frequent
case) it should be cheap.
Best Regards,
Aleksei
On 03/12/2019 06:09, Anuraag Agrawal wrote:
> Hi Aleksei,
>
> Thanks a lot for running the CI and even looking into the failures! I
> had only intended to update comments in the second patch and
> admittedly didn't actually run the code, obviously that wasn't a good
> idea... Here's an updated patch with the call to loadDNSConfig0()
> restored.
>
> 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..03c57da415 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 +25,10 @@
>
> 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 +51,69 @@ 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;
> + private static ArrayList<String> searchlist;
> + private static ArrayList<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<>();
> + // 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) {
> + ArrayList<String> l = allocateListForDelimitedString(str);
>
> - // comma and space are valid delimiters
> - StringTokenizer st = new StringTokenizer(str, ", ");
> + // String is delimited by space.
> + StringTokenizer st = new StringTokenizer(str, " ");
> while (st.hasMoreTokens()) {
> String s = st.nextToken();
> - if (!ll.contains(s)) {
> - ll.add(s);
> + if (!l.contains(s)) {
> + l.add(s);
> }
> }
> - return ll;
> + 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) {
> + ArrayList<String> l = allocateListForDelimitedString(str);
> +
> + // String is delimited by space
> + StringTokenizer st = new StringTokenizer(str, " ");
> + while (st.hasMoreTokens()) {
> + String s = st.nextToken();
> + if (!s.isEmpty()) {
> + if (s.indexOf(':') >= 0 && s.charAt(0) != '[') {
> + // Not BSD style
> + s = '[' + s + ']';
> + }
> + if (!l.contains(s)) {
> + l.add(s);
> + }
> + }
> + }
> + return l;
> + }
> +
> + private ArrayList<String> allocateListForDelimitedString(String
> str) {
> + int num = 0;
> + for (int i = 0; i < str.length(); i++) {
> + char c = str.charAt(i);
> + // String is space separated list of items
> + if (c == ' ') {
> + num++;
> + }
> + }
> + // Actual num is number of delimiters + 1
> + return new ArrayList<String>(num + 1);
> }
>
> // Load DNS configuration from OS
> @@ -81,28 +121,34 @@ 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..83100aa9ad 100644
> --- a/src/java.base/windows/native/libnet/ResolverConfigurationImpl.c
> +++ b/src/java.base/windows/native/libnet/ResolverConfigurationImpl.c
> @@ -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 Tue, Dec 3, 2019 at 1:24 AM Aleks Efimov <aleksej.efimov at oracle.com
> <mailto:aleksej.efimov at oracle.com>> wrote:
>
> Hey Anuraag,
>
> I've looked at the failures and I believe that your second patch
> accidentally removed 'loadDNSconfig0()' native call.
> Putting it back to
> src/java.base/windows/classes/sun/net/dns/ResolverConfigurationImpl.java:145
> resolves all these failures.
>
> -Aleksei
>
>
> On 02/12/2019 13:04, Aleks Efimov wrote:
>> Hi Anuraag,
>>
>> I've submited your patch to our CI system and I'm observing a
>> bunch of NPE failures with such stack trace:
>> java.lang.NullPointerException
>> at
>> java.base/sun.net.dns.ResolverConfigurationImpl.allocateListForDelimitedString(ResolverConfigurationImpl.java:108)
>> at
>> java.base/sun.net.dns.ResolverConfigurationImpl.stringToList(ResolverConfigurationImpl.java:68)
>> at
>> java.base/sun.net.dns.ResolverConfigurationImpl.loadConfig(ResolverConfigurationImpl.java:149)
>> at
>> java.base/sun.net.dns.ResolverConfigurationImpl.nameservers(ResolverConfigurationImpl.java:172)
>> at
>> jdk.naming.dns/com.sun.jndi.dns.DnsContextFactory.platformServersAvailable(DnsContextFactory.java:94)
>> at
>> jdk.naming.dns/com.sun.jndi.dns.DnsContextFactory.platformServersUsed(DnsContextFactory.java:171)
>> at
>> jdk.naming.dns/com.sun.jndi.dns.DnsContextFactory.getContext(DnsContextFactory.java:83)
>> at
>> jdk.naming.dns/com.sun.jndi.dns.DnsContextFactory.urlToContext(DnsContextFactory.java:120)
>> at
>> jdk.naming.dns/com.sun.jndi.dns.DnsContextFactory.getInitialContext(DnsContextFactory.java:64)
>> at
>> java.naming/javax.naming.spi.NamingManager.getInitialContext(NamingManager.java:730)
>> at
>> java.naming/javax.naming.InitialContext.getDefaultInitCtx(InitialContext.java:305)
>> at
>> java.naming/javax.naming.InitialContext.init(InitialContext.java:236)
>> at
>> java.naming/javax.naming.InitialContext.<init>(InitialContext.java:208)
>> at
>> java.naming/javax.naming.directory.InitialDirContext.<init>(InitialDirContext.java:130)
>> at LookupWithAnyAttrProp.runTest(LookupWithAnyAttrProp.java:57)
>> at TestBase.launch(TestBase.java:82)
>> at TestBase.run(TestBase.java:50)
>> at LookupWithAnyAttrProp.main(LookupWithAnyAttrProp.java:43)
>> at
>> java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native
>> Method)
>> at
>> java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
>> at
>> java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>> at java.base/java.lang.reflect.Method.invoke(Method.java:564)
>> at
>> com.sun.javatest.regtest.agent.MainWrapper$MainThread.run(MainWrapper.java:127)
>> at java.base/java.lang.Thread.run(Thread.java:832)
>>
>> Few examples of failing tests:
>> test/jdk/com/sun/jndi/dns/FedTests/ListSubInterior.java (and
>> others in the same folder)
>> test/jdk/com/sun/jndi/dns/FactoryTests/LookupWithAnyAttrProp.java
>> (and others in the same folder)
>>
>> Test platform is: Windows Server 2012 R2 6.3
>>
>> With Best Regards,
>> Aleksei
>>
>> On 25/11/2019 05:09, Anuraag Agrawal wrote:
>>> Hi Bernd,
>>>
>>> Thanks for the look and suggestion. I have updated those
>>> comments, as well as added several more to explain the native
>>> code aspects better which I hope helps future readers of the
>>> code. Hope it looks better now.
>>>
>>> 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..18996f0ee0 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 +25,10 @@
>>>
>>> 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 +51,69 @@ 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;
>>> + private static ArrayList<String> searchlist;
>>> + private static ArrayList<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<>();
>>> + // 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) {
>>> + ArrayList<String> l = allocateListForDelimitedString(str);
>>>
>>> - // comma and space are valid delimiters
>>> - StringTokenizer st = new StringTokenizer(str, ", ");
>>> + // String is delimited by space.
>>> + StringTokenizer st = new StringTokenizer(str, " ");
>>> while (st.hasMoreTokens()) {
>>> String s = st.nextToken();
>>> - if (!ll.contains(s)) {
>>> - ll.add(s);
>>> + if (!l.contains(s)) {
>>> + l.add(s);
>>> }
>>> }
>>> - return ll;
>>> + 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) {
>>> + ArrayList<String> l = allocateListForDelimitedString(str);
>>> +
>>> + // String is delimited by space
>>> + StringTokenizer st = new StringTokenizer(str, " ");
>>> + while (st.hasMoreTokens()) {
>>> + String s = st.nextToken();
>>> + if (!s.isEmpty()) {
>>> + if (s.indexOf(':') >= 0 && s.charAt(0) != '[') {
>>> + // Not BSD style
>>> + s = '[' + s + ']';
>>> + }
>>> + if (!l.contains(s)) {
>>> + l.add(s);
>>> + }
>>> + }
>>> + }
>>> + return l;
>>> + }
>>> +
>>> + private ArrayList<String>
>>> allocateListForDelimitedString(String str) {
>>> + int num = 0;
>>> + for (int i = 0; i < str.length(); i++) {
>>> + char c = str.charAt(i);
>>> + // String is space separated list of items
>>> + if (c == ' ') {
>>> + num++;
>>> + }
>>> + }
>>> + // Actual num is number of delimiters + 1
>>> + return new ArrayList<String>(num + 1);
>>> }
>>>
>>> // Load DNS configuration from OS
>>> @@ -81,28 +121,33 @@ 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
>>> - //
>>> - loadDNSconfig0();
>>> + // 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.
>>>
>>> - 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..83100aa9ad 100644
>>> ---
>>> a/src/java.base/windows/native/libnet/ResolverConfigurationImpl.c
>>> +++
>>> b/src/java.base/windows/native/libnet/ResolverConfigurationImpl.c
>>> @@ -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 Sun, Nov 24, 2019 at 11:21 PM Bernd Eckenfels
>>> <ecki at zusammenkunft.net <mailto:ecki at zusammenkunft.net>> wrote:
>>>
>>> Hello Anuraag,
>>>
>>> The patch looks like a good idea (especially the additional
>>> cleanup for nanos and arraylist) Just a minor thing I
>>> noticed there are two comments talking about „comma and
>>> space“ but the code below will only tokenize by space.
>>> Imguess the comment needs to be fixed, for the next review
>>> round.
>>>
>>> Gruss
>>> Bernd
>>> --
>>> http://bernd.eckenfels.net
>>> ------------------------------------------------------------------------
>>> *Von:* net-dev <net-dev-bounces at openjdk.java.net
>>> <mailto:net-dev-bounces at openjdk.java.net>> im Auftrag von
>>> Anuraag Agrawal <anuraaga at gmail.com <mailto:anuraaga at gmail.com>>
>>> *Gesendet:* Sonntag, November 24, 2019 10:47 AM
>>> *An:* net-dev at openjdk.java.net <mailto:net-dev at openjdk.java.net>
>>> *Betreff:* [PATCH] 7006496: Use modern Windows API to
>>> retrieve OS DNS servers
>>> Hello,
>>>
>>> While investigating DNS resolution failure using Netty
>>> (https://github.com/netty/netty/issues/9796), I came across
>>> an old JDK bug where on Windows, the list of OS name servers
>>> includes those for disabled interfaces
>>> (https://bugs.openjdk.java.net/browse/JDK-7006496). This is
>>> problematic since it will often include values from a
>>> previously registered network that is not available anymore,
>>> hence resolution requests would be guaranteed to fail.
>>>
>>> The current approach reads DNS name servers from the
>>> registry, where it isn't possible to read whether an adapter
>>> is actually enabled or not. However, Windows Vista+ (minimum
>>> JDK8+ supported Windows) include an API that can be used to
>>> examine whether an adapter is currently enabled, and also
>>> return its DNS servers. So I've created this patch to update
>>> the name server lookup to use this technique. I can confirm
>>> that now only name servers from enabled adapters are loaded.
>>> A side effect is the previous approach could only read IPv4
>>> - now IPv6 DNS servers are also loaded. The unix
>>> implementation seems to do this too, so I don't think this
>>> should cause issues but I can filter to only IPv4 to be more
>>> conservative if desired.
>>>
>>> I have also cleaned some low hanging fruit in what seems to
>>> be very old code
>>>
>>> - Use ArrayList instead of LinkedList since it can be
>>> accurately preallocated and is not mutated
>>> - Use nanoTime instead of currentTimeMillis for refresh
>>> timer to not cause problems during OS time changes.
>>> - Simplify tokenizer to only tokenize on space, there is
>>> never a comma separated list passed to it as we create the
>>> list in our JNI code
>>>
>>> This is my first patch for OpenJDK - happy to accept any
>>> feedback.
>>>
>>> Thanks for the consideration.
>>>
>>> Inlined patch follows (also attached but I've had attached
>>> patch scrubbed when submitting to jmh-dev before...)
>>>
>>> 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..dde871cf19 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 +25,10 @@
>>>
>>> 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 +51,65 @@ 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;
>>> + private static ArrayList<String> searchlist;
>>> + private static ArrayList<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<>();
>>> + // Parse string that consists of token delimited by space
>>> + // and return ArrayList
>>> + private ArrayList<String> stringToList(String str) {
>>> + ArrayList<String> l =
>>> allocateListForDelimitedString(str);
>>>
>>> // comma and space are valid delimiters
>>> - StringTokenizer st = new StringTokenizer(str, ", ");
>>> + StringTokenizer st = new StringTokenizer(str, " ");
>>> while (st.hasMoreTokens()) {
>>> String s = st.nextToken();
>>> - if (!ll.contains(s)) {
>>> - ll.add(s);
>>> + if (!l.contains(s)) {
>>> + l.add(s);
>>> }
>>> }
>>> - return ll;
>>> + return l;
>>> + }
>>> +
>>> + // Parse string that consists of token delimited by space
>>> + // and return ArrayList. Converts IPv6 addresses to
>>> BSD-style.
>>> + private ArrayList<String> addressesToList(String str) {
>>> + ArrayList<String> l =
>>> allocateListForDelimitedString(str);
>>> +
>>> + // comma and space are valid delimiters
>>> + StringTokenizer st = new StringTokenizer(str, " ");
>>> + while (st.hasMoreTokens()) {
>>> + String s = st.nextToken();
>>> + if (!s.isEmpty()) {
>>> + if (s.indexOf(':') >= 0 && s.charAt(0) !=
>>> '[') {
>>> + // Not BSD style
>>> + s = '[' + s + ']';
>>> + }
>>> + if (!l.contains(s)) {
>>> + l.add(s);
>>> + }
>>> + }
>>> + }
>>> + return l;
>>> + }
>>> +
>>> + private ArrayList<String>
>>> allocateListForDelimitedString(String str) {
>>> + int num = 0;
>>> + for (int i = 0; i < str.length(); i++) {
>>> + char c = str.charAt(i);
>>> + // String is space separated list of items
>>> + if (c == ' ') {
>>> + num++;
>>> + }
>>> + }
>>> + // Actual num is number of delimiters + 1
>>> + return new ArrayList<String>(num + 1);
>>> }
>>>
>>> // Load DNS configuration from OS
>>> @@ -88,8 +124,8 @@ public class ResolverConfigurationImpl
>>> changed = false;
>>> } else {
>>> if (lastRefresh >= 0) {
>>> - long currTime = System.currentTimeMillis();
>>> - if ((currTime - lastRefresh) < TIMEOUT) {
>>> + long currTime = System.nanoTime();
>>> + if ((currTime - lastRefresh) < TIMEOUT_NANOS) {
>>> return;
>>> }
>>> }
>>> @@ -100,9 +136,9 @@ public class ResolverConfigurationImpl
>>> //
>>> loadDNSconfig0();
>>>
>>> - lastRefresh = System.currentTimeMillis();
>>> + 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..83100aa9ad 100644
>>> ---
>>> a/src/java.base/windows/native/libnet/ResolverConfigurationImpl.c
>>> +++
>>> b/src/java.base/windows/native/libnet/ResolverConfigurationImpl.c
>>> @@ -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
>>>
>>
>
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