io.netty.resolver.dns

Class DnsNameResolver

java.lang.Object

io.netty.resolver.SimpleNameResolver<InetSocketAddress>

io.netty.resolver.dns.DnsNameResolver

All Implemented Interfaces:

NameResolver<InetSocketAddress>, Closeable, AutoCloseable

public class DnsNameResolver
extends SimpleNameResolver<InetSocketAddress>

A DNS-based NameResolver.

Constructor Summary

Constructors

Constructor and Description
DnsNameResolver(EventLoop eventLoop, ChannelFactory<? extends DatagramChannel> channelFactory, DnsServerAddresses nameServerAddresses) Creates a new DNS-based name resolver that communicates with the specified list of DNS servers.
DnsNameResolver(EventLoop eventLoop, ChannelFactory<? extends DatagramChannel> channelFactory, InetSocketAddress localAddress, DnsServerAddresses nameServerAddresses) Creates a new DNS-based name resolver that communicates with the specified list of DNS servers.
DnsNameResolver(EventLoop eventLoop, Class<? extends DatagramChannel> channelType, DnsServerAddresses nameServerAddresses) Creates a new DNS-based name resolver that communicates with the specified list of DNS servers.
DnsNameResolver(EventLoop eventLoop, Class<? extends DatagramChannel> channelType, InetSocketAddress localAddress, DnsServerAddresses nameServerAddresses) Creates a new DNS-based name resolver that communicates with the specified list of DNS servers.

Method Summary

Methods

Modifier and Type	Method and Description
DnsNameResolver	clearCache() Clears all the resolved addresses cached by this resolver.
boolean	clearCache(String hostname) Clears the resolved addresses of the specified host name from the cache of this resolver.
void	close() Closes the internal datagram channel used for sending and receiving DNS messages, and clears all DNS resource records from the cache.
protected boolean	doIsResolved(InetSocketAddress address) Invoked by SimpleNameResolver.isResolved(SocketAddress) to check if the specified address has been resolved already.
protected void	doResolve(InetSocketAddress unresolvedAddress, Promise<InetSocketAddress> promise) Invoked by SimpleNameResolver.resolve(SocketAddress) and SimpleNameResolver.resolve(String, int) to perform the actual name resolution.
protected void	doResolveAll(InetSocketAddress unresolvedAddress, Promise<List<InetSocketAddress>> promise) Invoked by SimpleNameResolver.resolveAll(SocketAddress) and SimpleNameResolver.resolveAll(String, int) 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(SocketAddress).
boolean	isRecursionDesired() Returns true if and only if this resolver sends a DNS query with the RD (recursion desired) flag set.
boolean	isTraceEnabled() Returns if this resolver should generate the detailed trace information in an exception message so that it is easier to understand the cause of resolution failure.
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.
int	maxTtl() Returns the maximum TTL of the cached DNS resource records (in seconds).
int	minTtl() Returns the minimum TTL of the cached DNS resource records (in seconds).
int	negativeTtl() Returns the TTL of the cache for the failed DNS queries (in seconds).
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(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.
long	queryTimeoutMillis() Returns the timeout of each DNS query performed by this resolver (in milliseconds).
List<InternetProtocolFamily>	resolveAddressTypes() Returns the list of the protocol families of the address resolved by SimpleNameResolver.resolve(SocketAddress) in the order of preference.
DnsNameResolver	setMaxPayloadSize(int maxPayloadSize) Sets the capacity of the datagram packet buffer (in bytes).
DnsNameResolver	setMaxQueriesPerResolve(int maxQueriesPerResolve) Sets the maximum allowed number of DNS queries to send when resolving a host name.
DnsNameResolver	setNegativeTtl(int negativeTtl) Sets the TTL of the cache for the failed DNS queries (in seconds).
DnsNameResolver	setQueryTimeoutMillis(long queryTimeoutMillis) Sets the timeout of each DNS query performed by this resolver (in milliseconds).
DnsNameResolver	setRecursionDesired(boolean recursionDesired) Sets if this resolver has to send a DNS query with the RD (recursion desired) flag set.
DnsNameResolver	setResolveAddressTypes(InternetProtocolFamily... resolveAddressTypes) Sets the list of the protocol families of the address resolved by SimpleNameResolver.resolve(SocketAddress).
DnsNameResolver	setResolveAddressTypes(Iterable<InternetProtocolFamily> resolveAddressTypes) Sets the list of the protocol families of the address resolved by SimpleNameResolver.resolve(SocketAddress).
DnsNameResolver	setTraceEnabled(boolean traceEnabled) Sets if this resolver should generate the detailed trace information in an exception message so that it is easier to understand the cause of resolution failure.
DnsNameResolver	setTtl(int minTtl, int maxTtl) Sets the minimum and maximum TTL of the cached DNS resource records (in seconds).

Methods inherited from class io.netty.resolver.SimpleNameResolver

isResolved, isSupported, resolve, resolve, resolve, resolve, resolveAll, resolveAll, resolveAll, resolveAll

Methods inherited from class java.lang.Object

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

Constructor Detail

DnsNameResolver

public DnsNameResolver(EventLoop eventLoop,
               Class<? extends DatagramChannel> channelType,
               DnsServerAddresses nameServerAddresses)

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

channelType - the type of the DatagramChannel to create

nameServerAddresses - the addresses of the DNS server. For each DNS query, a new stream is created from this to determine which DNS server should be contacted for the next retry in case of failure.

DnsNameResolver

public DnsNameResolver(EventLoop eventLoop,
               Class<? extends DatagramChannel> channelType,
               InetSocketAddress localAddress,
               DnsServerAddresses nameServerAddresses)

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

channelType - the type of the DatagramChannel to create

localAddress - the local address of the DatagramChannel

nameServerAddresses - the addresses of the DNS server. For each DNS query, a new stream is created from this to determine which DNS server should be contacted for the next retry in case of failure.

DnsNameResolver

public DnsNameResolver(EventLoop eventLoop,
               ChannelFactory<? extends DatagramChannel> channelFactory,
               DnsServerAddresses nameServerAddresses)

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

nameServerAddresses - the addresses of the DNS server. For each DNS query, a new stream is created from this to determine which DNS server should be contacted for the next retry in case of failure.

DnsNameResolver

public DnsNameResolver(EventLoop eventLoop,
               ChannelFactory<? extends DatagramChannel> channelFactory,
               InetSocketAddress localAddress,
               DnsServerAddresses nameServerAddresses)

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

localAddress - the local address of the DatagramChannel

nameServerAddresses - the addresses of the DNS server. For each DNS query, a new stream is created from this to determine which DNS server should be contacted for the next retry in case of failure.

Method Detail

minTtl

public int minTtl()

Returns the minimum TTL of the cached DNS resource records (in seconds).

See Also:

maxTtl(), setTtl(int, int)

maxTtl

public int maxTtl()

Returns the maximum TTL of the cached DNS resource records (in seconds).

See Also:

minTtl(), setTtl(int, int)

setTtl

public DnsNameResolver setTtl(int minTtl,
                     int maxTtl)

Sets the minimum and maximum TTL of the cached DNS resource records (in seconds). If the TTL of the DNS resource record returned by the DNS server is less than the minimum TTL or greater than the maximum TTL, this resolver will ignore the TTL from the DNS server and use the minimum TTL or the maximum TTL instead respectively. The default value is 0 and Integer.MAX_VALUE, which practically tells this resolver to respect the TTL from the DNS server.

Returns:

this

See Also:

minTtl(), maxTtl()

negativeTtl

public int negativeTtl()

Returns the TTL of the cache for the failed DNS queries (in seconds). The default value is 0, which disables the cache for negative results.

See Also:

setNegativeTtl(int)

setNegativeTtl

public DnsNameResolver setNegativeTtl(int negativeTtl)

Sets the TTL of the cache for the failed DNS queries (in seconds).

Returns:

this

See Also:

negativeTtl()

queryTimeoutMillis

public long queryTimeoutMillis()

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

See Also:

setQueryTimeoutMillis(long)

setQueryTimeoutMillis

public DnsNameResolver setQueryTimeoutMillis(long queryTimeoutMillis)

Sets the timeout of each DNS query performed by this resolver (in milliseconds).

Returns:

this

See Also:

queryTimeoutMillis()

resolveAddressTypes

public List<InternetProtocolFamily> resolveAddressTypes()

Returns the list of the protocol families of the address resolved by SimpleNameResolver.resolve(SocketAddress) in the order of preference. The default value depends on the value of the system property "java.net.preferIPv6Addresses".

See Also:

setResolveAddressTypes(InternetProtocolFamily...)

setResolveAddressTypes

public DnsNameResolver setResolveAddressTypes(InternetProtocolFamily... resolveAddressTypes)

Sets the list of the protocol families of the address resolved by SimpleNameResolver.resolve(SocketAddress). Usually, both InternetProtocolFamily.IPv4 and InternetProtocolFamily.IPv6 are specified in the order of preference. To enforce the resolve to retrieve the address of a specific protocol family, specify only a single InternetProtocolFamily.

Returns:

this

See Also:

resolveAddressTypes()

setResolveAddressTypes

public DnsNameResolver setResolveAddressTypes(Iterable<InternetProtocolFamily> resolveAddressTypes)

Sets the list of the protocol families of the address resolved by SimpleNameResolver.resolve(SocketAddress). Usually, both InternetProtocolFamily.IPv4 and InternetProtocolFamily.IPv6 are specified in the order of preference. To enforce the resolve to retrieve the address of a specific protocol family, specify only a single InternetProtocolFamily.

Returns:

this

See Also:

resolveAddressTypes()

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.

See Also:

setRecursionDesired(boolean)

setRecursionDesired

public DnsNameResolver setRecursionDesired(boolean recursionDesired)

Sets if this resolver has to send a DNS query with the RD (recursion desired) flag set.

Returns:

this

See Also:

isRecursionDesired()

maxQueriesPerResolve

public int maxQueriesPerResolve()

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

See Also:

setMaxQueriesPerResolve(int)

setMaxQueriesPerResolve

public DnsNameResolver setMaxQueriesPerResolve(int maxQueriesPerResolve)

Sets the maximum allowed number of DNS queries to send when resolving a host name.

Returns:

this

See Also:

maxQueriesPerResolve()

isTraceEnabled

public boolean isTraceEnabled()

Returns if this resolver should generate the detailed trace information in an exception message so that it is easier to understand the cause of resolution failure. The default value if true.

setTraceEnabled

public DnsNameResolver setTraceEnabled(boolean traceEnabled)

Sets if this resolver should generate the detailed trace information in an exception message so that it is easier to understand the cause of resolution failure.

maxPayloadSize

public int maxPayloadSize()

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

See Also:

setMaxPayloadSize(int)

setMaxPayloadSize

public DnsNameResolver setMaxPayloadSize(int maxPayloadSize)

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

Returns:

this

See Also:

maxPayloadSize()

clearCache

public DnsNameResolver clearCache()

Clears all the resolved addresses cached by this resolver.

Returns:

this

See Also:

clearCache(String)

clearCache

public boolean clearCache(String hostname)

Clears the resolved addresses of the specified host name from the cache of this resolver.

Returns:

true if and only if there was an entry for the specified host name in the cache and it has been removed by this method

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 NameResolver<InetSocketAddress>

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Overrides:

close in class SimpleNameResolver<InetSocketAddress>

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(SocketAddress).

Overrides:

executor in class SimpleNameResolver<InetSocketAddress>

doIsResolved

protected boolean doIsResolved(InetSocketAddress address)

Description copied from class: SimpleNameResolver

Invoked by SimpleNameResolver.isResolved(SocketAddress) to check if the specified address has been resolved already.

Specified by:

doIsResolved in class SimpleNameResolver<InetSocketAddress>

doResolve

protected void doResolve(InetSocketAddress unresolvedAddress,
             Promise<InetSocketAddress> promise)
                  throws Exception

Description copied from class: SimpleNameResolver

Invoked by SimpleNameResolver.resolve(SocketAddress) and SimpleNameResolver.resolve(String, int) to perform the actual name resolution.

Specified by:

doResolve in class SimpleNameResolver<InetSocketAddress>

Throws:

Exception

doResolveAll

protected void doResolveAll(InetSocketAddress unresolvedAddress,
                Promise<List<InetSocketAddress>> promise)
                     throws Exception

Description copied from class: SimpleNameResolver

Invoked by SimpleNameResolver.resolveAll(SocketAddress) and SimpleNameResolver.resolveAll(String, int) to perform the actual name resolution.

Specified by:

doResolveAll in class SimpleNameResolver<InetSocketAddress>

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,
                                                             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,
                                                             Promise<AddressedEnvelope<? extends DnsResponse,InetSocketAddress>> promise)

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