org.xbill.DNS

Class ExtendedResolver

java.lang.Object

org.xbill.DNS.ExtendedResolver

All Implemented Interfaces:

Resolver

public class ExtendedResolver
extends java.lang.Object
implements Resolver

An implementation of Resolver that can send queries to multiple servers, sending the queries multiple times if necessary.

See Also:

Resolver

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private static class	ExtendedResolver.Resolution
private static class	ExtendedResolver.ResolverEntry

Field Summary

Fields

Modifier and Type	Field and Description
static java.time.Duration	DEFAULT_RESOLVER_TIMEOUT Default timeout until resolving with one of the used resolvers fails.
static java.time.Duration	DEFAULT_TIMEOUT Default timeout until resolving is aborted.
private java.util.concurrent.atomic.AtomicInteger	lbStart
private boolean	loadBalance
private java.util.List<ExtendedResolver.ResolverEntry>	resolvers
private int	retries
private java.time.Duration	timeout

Constructor Summary

Constructors

Constructor and Description
ExtendedResolver() Creates a new Extended Resolver.
ExtendedResolver(java.lang.Iterable<Resolver> resolvers) Creates a new ExtendedResolver.
ExtendedResolver(Resolver[] resolvers) Creates a new Extended Resolver
ExtendedResolver(java.lang.String[] servers) Creates a new instance with SimpleResolvers.

Method Summary

Modifier and Type	Method and Description
void	addResolver(Resolver r) Adds a new resolver to be used by this ExtendedResolver
void	deleteResolver(Resolver r) Deletes a resolver used by this ExtendedResolver
boolean	getLoadBalance() Gets whether the servers receive queries load balanced.
Resolver	getResolver(int n) Returns the nth resolver used by this ExtendedResolver
Resolver[]	getResolvers() Returns all resolvers used by this ExtendedResolver
int	getRetries() Gets the number of retries sent to each server per query.
java.time.Duration	getTimeout() Gets the amount of time to wait for a response before giving up.
java.util.concurrent.CompletionStage<Message>	sendAsync(Message query) Sends a message to multiple servers, and queries are sent multiple times until either a successful response is received, or it is clear that there is no successful response.
java.util.concurrent.CompletionStage<Message>	sendAsync(Message query, java.util.concurrent.Executor executor) Sends a message to multiple servers, and queries are sent multiple times until either a successful response is received, or it is clear that there is no successful response.
void	setEDNS(int version, int payloadSize, int flags, java.util.List<EDNSOption> options) Sets the EDNS information on outgoing messages.
void	setIgnoreTruncation(boolean flag) Sets whether truncated responses will be ignored.
void	setLoadBalance(boolean flag) Sets whether the servers should be load balanced.
void	setPort(int port) Sets the port to communicate with on the server
void	setRetries(int retries) Sets the number of retries sent to each server per query
void	setTCP(boolean flag) Sets whether TCP connections will be used by default
void	setTimeout(java.time.Duration timeout) Sets the timeout for the ExtendedResolver.
void	setTSIGKey(TSIG key) Specifies the TSIG key that messages will be signed with
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.xbill.DNS.Resolver

send, sendAsync, setEDNS, setEDNS, setTimeout, setTimeout

Field Detail

DEFAULT_TIMEOUT

public static final java.time.Duration DEFAULT_TIMEOUT

Default timeout until resolving is aborted.

Since:

3.2

DEFAULT_RESOLVER_TIMEOUT

public static final java.time.Duration DEFAULT_RESOLVER_TIMEOUT

Default timeout until resolving with one of the used resolvers fails.

Since:

3.2

resolvers

private final java.util.List<ExtendedResolver.ResolverEntry> resolvers

lbStart

private final java.util.concurrent.atomic.AtomicInteger lbStart

loadBalance

private boolean loadBalance

retries

private int retries

timeout

private java.time.Duration timeout

Constructor Detail

ExtendedResolver

public ExtendedResolver()

Creates a new Extended Resolver. The default ResolverConfig is used to determine the servers for which SimpleResolvers are initialized. The timeout for each server is initialized with DEFAULT_RESOLVER_TIMEOUT.

ExtendedResolver

public ExtendedResolver(java.lang.String[] servers)
                 throws java.net.UnknownHostException

Creates a new instance with SimpleResolvers. The timeout for each server is initialized with DEFAULT_RESOLVER_TIMEOUT.

Parameters:

servers - An array of server names or IP addresses for which SimpleResolvers are initialized.

Throws:

java.net.UnknownHostException - A server name could not be resolved

ExtendedResolver

public ExtendedResolver(Resolver[] resolvers)

Creates a new Extended Resolver

Parameters:

resolvers - An array of pre-initialized Resolvers.

ExtendedResolver

public ExtendedResolver(java.lang.Iterable<Resolver> resolvers)

Creates a new ExtendedResolver. No timeout value is applied to the individual resolvers, make sure their timeout is smaller than the timeout of this ExtendedResolver.

Parameters:

resolvers - An iterable of pre-initialized Resolvers.

Method Detail

setPort

public void setPort(int port)

Description copied from interface: Resolver

Sets the port to communicate with on the server

Specified by:

setPort in interface Resolver

Parameters:

port - The port to send messages to

setTCP

public void setTCP(boolean flag)

Description copied from interface: Resolver

Sets whether TCP connections will be used by default

Specified by:

setTCP in interface Resolver

Parameters:

flag - Indicates whether TCP connections are made

setIgnoreTruncation

public void setIgnoreTruncation(boolean flag)

Description copied from interface: Resolver

Sets whether truncated responses will be ignored. If not, a truncated response over UDP will cause a retransmission over TCP.

Specified by:

setIgnoreTruncation in interface Resolver

Parameters:

flag - Indicates whether truncated responses should be ignored.

setEDNS

public void setEDNS(int version,
                    int payloadSize,
                    int flags,
                    java.util.List<EDNSOption> options)

Description copied from interface: Resolver

Sets the EDNS information on outgoing messages.

Specified by:

setEDNS in interface Resolver

Parameters:

version - The EDNS version to use. 0 indicates EDNS0 and -1 indicates no EDNS.

payloadSize - The maximum DNS packet size that this host is capable of receiving over UDP. If 0 is specified, the default (1280) is used.

flags - EDNS extended flags to be set in the OPT record.

options - EDNS options to be set in the OPT record, specified as a List of OPTRecord.Option elements.

See Also:

OPTRecord

setTSIGKey

public void setTSIGKey(TSIG key)

Description copied from interface: Resolver

Specifies the TSIG key that messages will be signed with

Specified by:

setTSIGKey in interface Resolver

Parameters:

key - The key

getTimeout

public java.time.Duration getTimeout()

Description copied from interface: Resolver

Gets the amount of time to wait for a response before giving up.

Specified by:

getTimeout in interface Resolver

See Also:

Resolver.setTimeout(Duration)

setTimeout

public void setTimeout(java.time.Duration timeout)

Sets the timeout for the ExtendedResolver.

Note that this only sets the timeout for the ExtendedResolver, not the individual Resolvers. If the timeout expires, the ExtendedResolver simply stops retrying, it does not abort running queries. The timeout value must be larger than that for the individual resolver to have any effect.

Specified by:

setTimeout in interface Resolver

Parameters:

timeout - The amount of time to wait before sending further queries.

See Also:

ExtendedResolver(), ExtendedResolver(String[])

sendAsync

public java.util.concurrent.CompletionStage<Message> sendAsync(Message query)

Sends a message to multiple servers, and queries are sent multiple times until either a successful response is received, or it is clear that there is no successful response.

Specified by:

sendAsync in interface Resolver

Parameters:

query - The query to send.

Returns:

A future that completes when the query is finished.

sendAsync

public java.util.concurrent.CompletionStage<Message> sendAsync(Message query,
                                                               java.util.concurrent.Executor executor)

Sends a message to multiple servers, and queries are sent multiple times until either a successful response is received, or it is clear that there is no successful response.

Specified by:

sendAsync in interface Resolver

Parameters:

query - The query to send.

executor - The service to use for async operations.

Returns:

A future that completes when the query is finished.

getResolver

public Resolver getResolver(int n)

Returns the nth resolver used by this ExtendedResolver

getResolvers

public Resolver[] getResolvers()

Returns all resolvers used by this ExtendedResolver

addResolver

public void addResolver(Resolver r)

Adds a new resolver to be used by this ExtendedResolver

deleteResolver

public void deleteResolver(Resolver r)

Deletes a resolver used by this ExtendedResolver

getLoadBalance

public boolean getLoadBalance()

Gets whether the servers receive queries load balanced.

Since:

3.2

setLoadBalance

public void setLoadBalance(boolean flag)

Sets whether the servers should be load balanced.

Parameters:

flag - If true, servers will be tried in round-robin order. If false, servers will always be queried in the same order.

getRetries

public int getRetries()

Gets the number of retries sent to each server per query.

Since:

3.2

setRetries

public void setRetries(int retries)

Sets the number of retries sent to each server per query

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object