Class DnsNameResolver

java.lang.Object

io.netty.resolver.SimpleNameResolver<InetAddress>

io.netty.resolver.InetNameResolver

io.netty.resolver.dns.DnsNameResolver

All Implemented Interfaces:

NameResolver<InetAddress>, Closeable, AutoCloseable

public class DnsNameResolver
extends InetNameResolver

A DNS-based InetNameResolver.

Field Summary

Fields

Modifier and Type	Field	Description
static final AttributeKey<Boolean>	DNS_PIPELINE_ATTRIBUTE	An attribute used to mark all channels created by the DnsNameResolver.

Constructor Summary

Constructors

Constructor	Description
DnsNameResolver(EventLoop eventLoop, ChannelFactory<? extends DatagramChannel> channelFactory, DnsCache resolveCache, AuthoritativeDnsServerCache authoritativeDnsServerCache, DnsQueryLifecycleObserverFactory dnsQueryLifecycleObserverFactory, long queryTimeoutMillis, ResolvedAddressTypes resolvedAddressTypes, boolean recursionDesired, int maxQueriesPerResolve, boolean traceEnabled, int maxPayloadSize, boolean optResourceEnabled, HostsFileEntriesResolver hostsFileEntriesResolver, DnsServerAddressStreamProvider dnsServerAddressStreamProvider, String[] searchDomains, int ndots, boolean decodeIdn)	Deprecated. Use DnsNameResolverBuilder.
DnsNameResolver(EventLoop eventLoop, ChannelFactory<? extends DatagramChannel> channelFactory, DnsCache resolveCache, DnsCache authoritativeDnsServerCache, DnsQueryLifecycleObserverFactory dnsQueryLifecycleObserverFactory, long queryTimeoutMillis, ResolvedAddressTypes resolvedAddressTypes, boolean recursionDesired, int maxQueriesPerResolve, boolean traceEnabled, int maxPayloadSize, boolean optResourceEnabled, HostsFileEntriesResolver hostsFileEntriesResolver, DnsServerAddressStreamProvider dnsServerAddressStreamProvider, String[] searchDomains, int ndots, boolean decodeIdn)	Deprecated. Use DnsNameResolverBuilder.

Method Summary

Modifier and Type	Method	Description
AuthoritativeDnsServerCache	authoritativeDnsServerCache()	Returns the cache used for authoritative DNS servers for a domain.
void	close()	Closes the internal datagram channel used for sending and receiving DNS messages, and clears all DNS resource records from the cache.
DnsCnameCache	cnameCache()	Returns the DnsCnameCache.
protected void	doResolve(String inetHost, DnsRecord[] additionals, Promise<InetAddress> promise, DnsCache resolveCache)	Hook designed for extensibility so one can pass a different cache on each resolution attempt instead of using the global one.
protected void	doResolve(String inetHost, Promise<InetAddress> promise)	Invoked by SimpleNameResolver.resolve(String) to perform the actual name resolution.
protected void	doResolveAll(String inetHost, DnsRecord[] additionals, Promise<List<InetAddress>> promise, DnsCache resolveCache)	Hook designed for extensibility so one can pass a different cache on each resolution attempt instead of using the global one.
protected void	doResolveAll(String inetHost, Promise<List<InetAddress>> promise)	Invoked by SimpleNameResolver.resolveAll(String) to perform the actual name resolution.
protected EventLoop	executor()	Returns the EventExecutor which is used to notify the listeners of the Future returned by SimpleNameResolver.resolve(String).
HostsFileEntriesResolver	hostsFileEntriesResolver()	Returns the component that tries to resolve hostnames against the hosts file prior to asking to remotes DNS servers.
boolean	isCaseRandomizationEnabled()	Returns true if the case of the name in the questions of UDP queries is randomized ("0x20").
boolean	isDnsCookiesEnabled()	Returns true if a client cookie as defined by RFC 7873 is sent with UDP queries and validated in the responses.
boolean	isOptResourceEnabled()	Returns the automatic inclusion of a optional records that tries to give the remote DNS server a hint about how much data the resolver can read per response is enabled.
boolean	isRecursionDesired()	Returns true if and only if this resolver sends a DNS query with the RD (recursion desired) flag set.
static boolean	isTimeoutError(Throwable cause)	Returns true if the Throwable was caused by an timeout.
static boolean	isTransportOrTimeoutError(Throwable cause)	Returns true if the Throwable was caused by an timeout or transport error.
int	maxPayloadSize()	Returns the capacity of the datagram packet buffer (in bytes).
int	maxQueriesPerResolve()	Returns the maximum allowed number of DNS queries to send when resolving a host name.
protected DnsServerAddressStream	newRedirectDnsServerStream(String hostname, List<InetSocketAddress> nameservers)	Creates a new DnsServerAddressStream to following a redirected DNS query.
Future<AddressedEnvelope<DnsResponse, InetSocketAddress>>	query(DnsQuestion question)	Sends a DNS query with the specified question.
Future<AddressedEnvelope<DnsResponse, InetSocketAddress>>	query(DnsQuestion question, Promise<AddressedEnvelope<? extends DnsResponse, InetSocketAddress>> promise)	Sends a DNS query with the specified question.
Future<AddressedEnvelope<DnsResponse, InetSocketAddress>>	query(DnsQuestion question, Iterable<DnsRecord> additionals)	Sends a DNS query with the specified question with additional records.
Future<AddressedEnvelope<DnsResponse, InetSocketAddress>>	query(InetSocketAddress nameServerAddr, DnsQuestion question)	Sends a DNS query with the specified question using the specified name server list.
Future<AddressedEnvelope<DnsResponse, InetSocketAddress>>	query(InetSocketAddress nameServerAddr, DnsQuestion question, Promise<AddressedEnvelope<? extends DnsResponse, InetSocketAddress>> promise)	Sends a DNS query with the specified question using the specified name server list.
Future<AddressedEnvelope<DnsResponse, InetSocketAddress>>	query(InetSocketAddress nameServerAddr, DnsQuestion question, Iterable<DnsRecord> additionals)	Sends a DNS query with the specified question with additional records using the specified name server list.
Future<AddressedEnvelope<DnsResponse, InetSocketAddress>>	query(InetSocketAddress nameServerAddr, DnsQuestion question, Iterable<DnsRecord> additionals, Promise<AddressedEnvelope<? extends DnsResponse, InetSocketAddress>> promise)	Sends a DNS query with the specified question with additional records using the specified name server list.
DnsServerAddressStream	queryDnsServerAddressStream()	Returns the dns server address stream used for DNS queries (not resolve).
long	queryTimeoutMillis()	Returns the timeout of each DNS query performed by this resolver (in milliseconds).
final Future<InetAddress>	resolve(String inetHost, Iterable<DnsRecord> additionals)	Resolves the specified name into an address.
final Future<InetAddress>	resolve(String inetHost, Iterable<DnsRecord> additionals, Promise<InetAddress> promise)	Resolves the specified name into an address.
final Future<List<DnsRecord>>	resolveAll(DnsQuestion question)	Resolves the DnsRecords that are matched by the specified DnsQuestion.
final Future<List<DnsRecord>>	resolveAll(DnsQuestion question, Iterable<DnsRecord> additionals)	Resolves the DnsRecords that are matched by the specified DnsQuestion.
final Future<List<DnsRecord>>	resolveAll(DnsQuestion question, Iterable<DnsRecord> additionals, Promise<List<DnsRecord>> promise)	Resolves the DnsRecords that are matched by the specified DnsQuestion.
final Future<List<InetAddress>>	resolveAll(String inetHost, Iterable<DnsRecord> additionals)	Resolves the specified host name and port into a list of address.
final Future<List<InetAddress>>	resolveAll(String inetHost, Iterable<DnsRecord> additionals, Promise<List<InetAddress>> promise)	Resolves the specified host name and port into a list of address.
DnsCache	resolveCache()	Returns the resolution cache.
ResolvedAddressTypes	resolvedAddressTypes()	Returns the ResolvedAddressTypes resolved by SimpleNameResolver.resolve(String).

Methods inherited from class InetNameResolver

asAddressResolver

Modifier and Type	Method	Description
AddressResolver<InetSocketAddress>	asAddressResolver()	Return a AddressResolver that will use this name resolver underneath.

Methods inherited from class SimpleNameResolver

resolve, resolve, resolveAll, resolveAll

Modifier and Type	Method	Description
final Future<InetAddress>	resolve(String inetHost)	Resolves the specified name into an address.
Future<InetAddress>	resolve(String inetHost, Promise<InetAddress> promise)	Resolves the specified name into an address.
final Future<List<InetAddress>>	resolveAll(String inetHost)	Resolves the specified host name and port into a list of address.
Future<List<InetAddress>>	resolveAll(String inetHost, Promise<List<InetAddress>> promise)	Resolves the specified host name and port into a list of address.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

DNS_PIPELINE_ATTRIBUTE

public static final AttributeKey<Boolean> DNS_PIPELINE_ATTRIBUTE

An attribute used to mark all channels created by the DnsNameResolver.

Constructor Details

DnsNameResolver

@Deprecated
public DnsNameResolver(EventLoop eventLoop,
 ChannelFactory<? extends DatagramChannel> channelFactory,
 DnsCache resolveCache,
 DnsCache authoritativeDnsServerCache,
 DnsQueryLifecycleObserverFactory dnsQueryLifecycleObserverFactory,
 long queryTimeoutMillis,
 ResolvedAddressTypes resolvedAddressTypes,
 boolean recursionDesired,
 int maxQueriesPerResolve,
 boolean traceEnabled,
 int maxPayloadSize,
 boolean optResourceEnabled,
 HostsFileEntriesResolver hostsFileEntriesResolver,
 DnsServerAddressStreamProvider dnsServerAddressStreamProvider,
 String[] searchDomains,
 int ndots,
 boolean decodeIdn)

Deprecated.

Use DnsNameResolverBuilder.

Creates a new DNS-based name resolver that communicates with the specified list of DNS servers.

Parameters:

eventLoop - the EventLoop which will perform the communication with the DNS servers

channelFactory - the ChannelFactory that will create a DatagramChannel

resolveCache - the DNS resolved entries cache

authoritativeDnsServerCache - the cache used to find the authoritative DNS server for a domain

dnsQueryLifecycleObserverFactory - used to generate new instances of DnsQueryLifecycleObserver which can be used to track metrics for DNS servers.

queryTimeoutMillis - timeout of each DNS query in millis. 0 disables the timeout. If not set or a negative number is set, the default timeout is used.

resolvedAddressTypes - the preferred address types

recursionDesired - if recursion desired flag must be set

maxQueriesPerResolve - the maximum allowed number of DNS queries for a given name resolution

traceEnabled - if trace is enabled

maxPayloadSize - the capacity of the datagram packet buffer

optResourceEnabled - if automatic inclusion of a optional records is enabled

hostsFileEntriesResolver - the HostsFileEntriesResolver used to check for local aliases

dnsServerAddressStreamProvider - The DnsServerAddressStreamProvider used to determine the name servers for each hostname lookup.

searchDomains - the list of search domain (can be null, if so, will try to default to the underlying platform ones)

ndots - the ndots value

decodeIdn - true if domain / host names should be decoded to unicode when received. See rfc3492.

DnsNameResolver

@Deprecated
public DnsNameResolver(EventLoop eventLoop,
 ChannelFactory<? extends DatagramChannel> channelFactory,
 DnsCache resolveCache,
 AuthoritativeDnsServerCache authoritativeDnsServerCache,
 DnsQueryLifecycleObserverFactory dnsQueryLifecycleObserverFactory,
 long queryTimeoutMillis,
 ResolvedAddressTypes resolvedAddressTypes,
 boolean recursionDesired,
 int maxQueriesPerResolve,
 boolean traceEnabled,
 int maxPayloadSize,
 boolean optResourceEnabled,
 HostsFileEntriesResolver hostsFileEntriesResolver,
 DnsServerAddressStreamProvider dnsServerAddressStreamProvider,
 String[] searchDomains,
 int ndots,
 boolean decodeIdn)

Deprecated.

Use DnsNameResolverBuilder.

Creates a new DNS-based name resolver that communicates with the specified list of DNS servers.

Parameters:

eventLoop - the EventLoop which will perform the communication with the DNS servers

channelFactory - the ChannelFactory that will create a DatagramChannel

resolveCache - the DNS resolved entries cache

authoritativeDnsServerCache - the cache used to find the authoritative DNS server for a domain

dnsQueryLifecycleObserverFactory - used to generate new instances of DnsQueryLifecycleObserver which can be used to track metrics for DNS servers.

queryTimeoutMillis - timeout of each DNS query in millis. 0 disables the timeout. If not set or a negative number is set, the default timeout is used.

resolvedAddressTypes - the preferred address types

recursionDesired - if recursion desired flag must be set

maxQueriesPerResolve - the maximum allowed number of DNS queries for a given name resolution

traceEnabled - if trace is enabled

maxPayloadSize - the capacity of the datagram packet buffer

optResourceEnabled - if automatic inclusion of a optional records is enabled

hostsFileEntriesResolver - the HostsFileEntriesResolver used to check for local aliases

dnsServerAddressStreamProvider - The DnsServerAddressStreamProvider used to determine the name servers for each hostname lookup.

searchDomains - the list of search domain (can be null, if so, will try to default to the underlying platform ones)

ndots - the ndots value

decodeIdn - true if domain / host names should be decoded to unicode when received. See rfc3492.

Method Details

newRedirectDnsServerStream

protected DnsServerAddressStream newRedirectDnsServerStream(String hostname,
 List<InetSocketAddress> nameservers)

Creates a new DnsServerAddressStream to following a redirected DNS query. By overriding this it provides the opportunity to sort the name servers before following a redirected DNS query.

Parameters:

hostname - the hostname.

nameservers - The addresses of the DNS servers which are used in the event of a redirect. This may contain resolved and unresolved addresses so the used DnsServerAddressStream must allow unresolved addresses if you want to include these as well.

Returns:

A DnsServerAddressStream which will be used to follow the DNS redirect or null if none should be followed.

resolveCache

public DnsCache resolveCache()

Returns the resolution cache.

cnameCache

public DnsCnameCache cnameCache()

Returns the DnsCnameCache.

authoritativeDnsServerCache

public AuthoritativeDnsServerCache authoritativeDnsServerCache()

Returns the cache used for authoritative DNS servers for a domain.

queryTimeoutMillis

public long queryTimeoutMillis()

Returns the timeout of each DNS query performed by this resolver (in milliseconds). The default value is 5 seconds.

queryDnsServerAddressStream

public DnsServerAddressStream queryDnsServerAddressStream()

Returns the dns server address stream used for DNS queries (not resolve).

resolvedAddressTypes

public ResolvedAddressTypes resolvedAddressTypes()

Returns the ResolvedAddressTypes resolved by SimpleNameResolver.resolve(String). The default value depends on the value of the system property "java.net.preferIPv6Addresses".

isRecursionDesired

public boolean isRecursionDesired()

Returns true if and only if this resolver sends a DNS query with the RD (recursion desired) flag set. The default value is true.

maxQueriesPerResolve

public int maxQueriesPerResolve()

Returns the maximum allowed number of DNS queries to send when resolving a host name. The default value is 8.

maxPayloadSize

public int maxPayloadSize()

Returns the capacity of the datagram packet buffer (in bytes). The default value is 4096 bytes.

isCaseRandomizationEnabled

public boolean isCaseRandomizationEnabled()

Returns true if the case of the name in the questions of UDP queries is randomized ("0x20").

isDnsCookiesEnabled

public boolean isDnsCookiesEnabled()

Returns true if a client cookie as defined by RFC 7873 is sent with UDP queries and validated in the responses.

isOptResourceEnabled

public boolean isOptResourceEnabled()

Returns the automatic inclusion of a optional records that tries to give the remote DNS server a hint about how much data the resolver can read per response is enabled.

hostsFileEntriesResolver

public HostsFileEntriesResolver hostsFileEntriesResolver()

Returns the component that tries to resolve hostnames against the hosts file prior to asking to remotes DNS servers.

close

public void close()

Closes the internal datagram channel used for sending and receiving DNS messages, and clears all DNS resource records from the cache. Attempting to send a DNS query or to resolve a domain name will fail once this method has been called.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Specified by:

close in interface NameResolver<InetAddress>

Overrides:

close in class SimpleNameResolver<InetAddress>

executor

protected EventLoop executor()

Description copied from class: SimpleNameResolver

Returns the EventExecutor which is used to notify the listeners of the Future returned by SimpleNameResolver.resolve(String).

Overrides:

executor in class SimpleNameResolver<InetAddress>

resolve

public final Future<InetAddress> resolve(String inetHost,
 Iterable<DnsRecord> additionals)

Resolves the specified name into an address.

Parameters:

inetHost - the name to resolve

additionals - additional records (OPT)

Returns:

the address as the result of the resolution

resolve

public final Future<InetAddress> resolve(String inetHost,
 Iterable<DnsRecord> additionals,
 Promise<InetAddress> promise)

Resolves the specified name into an address.

Parameters:

inetHost - the name to resolve

additionals - additional records (OPT)

promise - the Promise which will be fulfilled when the name resolution is finished

Returns:

the address as the result of the resolution

resolveAll

public final Future<List<InetAddress>> resolveAll(String inetHost,
 Iterable<DnsRecord> additionals)

Resolves the specified host name and port into a list of address.

Parameters:

inetHost - the name to resolve

additionals - additional records (OPT)

Returns:

the list of the address as the result of the resolution

resolveAll

public final Future<List<InetAddress>> resolveAll(String inetHost,
 Iterable<DnsRecord> additionals,
 Promise<List<InetAddress>> promise)

Resolves the specified host name and port into a list of address.

Parameters:

inetHost - the name to resolve

additionals - additional records (OPT)

promise - the Promise which will be fulfilled when the name resolution is finished

Returns:

the list of the address as the result of the resolution

doResolve

protected void doResolve(String inetHost,
 Promise<InetAddress> promise)
                  throws Exception

Description copied from class: SimpleNameResolver

Invoked by SimpleNameResolver.resolve(String) to perform the actual name resolution.

Specified by:

doResolve in class SimpleNameResolver<InetAddress>

Throws:

Exception

resolveAll

public final Future<List<DnsRecord>> resolveAll(DnsQuestion question)

Resolves the DnsRecords that are matched by the specified DnsQuestion. Unlike query(DnsQuestion), this method handles redirection, CNAMEs and multiple name servers. If the specified DnsQuestion is A or AAAA, this method looks up the configured HostsFileEntries before sending a query to the name servers. If a match is found in the HostsFileEntries, a synthetic A or AAAA record will be returned.

Parameters:

question - the question

Returns:

the list of the DnsRecords as the result of the resolution

resolveAll

public final Future<List<DnsRecord>> resolveAll(DnsQuestion question,
 Iterable<DnsRecord> additionals)

Resolves the DnsRecords that are matched by the specified DnsQuestion. Unlike query(DnsQuestion), this method handles redirection, CNAMEs and multiple name servers. If the specified DnsQuestion is A or AAAA, this method looks up the configured HostsFileEntries before sending a query to the name servers. If a match is found in the HostsFileEntries, a synthetic A or AAAA record will be returned.

Parameters:

question - the question

additionals - additional records (OPT)

Returns:

the list of the DnsRecords as the result of the resolution

resolveAll

public final Future<List<DnsRecord>> resolveAll(DnsQuestion question,
 Iterable<DnsRecord> additionals,
 Promise<List<DnsRecord>> promise)

Resolves the DnsRecords that are matched by the specified DnsQuestion. Unlike query(DnsQuestion), this method handles redirection, CNAMEs and multiple name servers. If the specified DnsQuestion is A or AAAA, this method looks up the configured HostsFileEntries before sending a query to the name servers. If a match is found in the HostsFileEntries, a synthetic A or AAAA record will be returned.

Parameters:

question - the question

additionals - additional records (OPT)

promise - the Promise which will be fulfilled when the resolution is finished

Returns:

the list of the DnsRecords as the result of the resolution

doResolve

protected void doResolve(String inetHost,
 DnsRecord[] additionals,
 Promise<InetAddress> promise,
 DnsCache resolveCache)
                  throws Exception

Hook designed for extensibility so one can pass a different cache on each resolution attempt instead of using the global one.

Throws:

Exception

doResolveAll

protected void doResolveAll(String inetHost,
 Promise<List<InetAddress>> promise)
                     throws Exception

Description copied from class: SimpleNameResolver

Invoked by SimpleNameResolver.resolveAll(String) to perform the actual name resolution.

Specified by:

doResolveAll in class SimpleNameResolver<InetAddress>

Throws:

Exception

doResolveAll

protected void doResolveAll(String inetHost,
 DnsRecord[] additionals,
 Promise<List<InetAddress>> promise,
 DnsCache resolveCache)
                     throws Exception

Hook designed for extensibility so one can pass a different cache on each resolution attempt instead of using the global one.

Throws:

Exception

query

public Future<AddressedEnvelope<DnsResponse, InetSocketAddress>> query(DnsQuestion question)

Sends a DNS query with the specified question.

query

public Future<AddressedEnvelope<DnsResponse, InetSocketAddress>> query(DnsQuestion question,
 Iterable<DnsRecord> additionals)

Sends a DNS query with the specified question with additional records.

query

public Future<AddressedEnvelope<DnsResponse, InetSocketAddress>> query(DnsQuestion question,
 Promise<AddressedEnvelope<? extends DnsResponse, InetSocketAddress>> promise)

Sends a DNS query with the specified question.

query

public Future<AddressedEnvelope<DnsResponse, InetSocketAddress>> query(InetSocketAddress nameServerAddr,
 DnsQuestion question)

Sends a DNS query with the specified question using the specified name server list.

query

public Future<AddressedEnvelope<DnsResponse, InetSocketAddress>> query(InetSocketAddress nameServerAddr,
 DnsQuestion question,
 Iterable<DnsRecord> additionals)

Sends a DNS query with the specified question with additional records using the specified name server list.

query

public Future<AddressedEnvelope<DnsResponse, InetSocketAddress>> query(InetSocketAddress nameServerAddr,
 DnsQuestion question,
 Promise<AddressedEnvelope<? extends DnsResponse, InetSocketAddress>> promise)

Sends a DNS query with the specified question using the specified name server list.

query

public Future<AddressedEnvelope<DnsResponse, InetSocketAddress>> query(InetSocketAddress nameServerAddr,
 DnsQuestion question,
 Iterable<DnsRecord> additionals,
 Promise<AddressedEnvelope<? extends DnsResponse, InetSocketAddress>> promise)

Sends a DNS query with the specified question with additional records using the specified name server list.

isTransportOrTimeoutError

public static boolean isTransportOrTimeoutError(Throwable cause)

Returns true if the Throwable was caused by an timeout or transport error. These methods can be used on the Future.cause() that is returned by the various methods exposed by this DnsNameResolver.

isTimeoutError

public static boolean isTimeoutError(Throwable cause)

Returns true if the Throwable was caused by an timeout. These methods can be used on the Future.cause() that is returned by the various methods exposed by this DnsNameResolver.