DnsResolver

public final class DnsResolver
extends Object

java.lang.Object
   ↳ android.net.DnsResolver

Dns resolver class for asynchronous dns querying Note that if a client sends a query with more than 1 record in the question section but the remote dns server does not support this, it may not respond at all, leading to a timeout.

Summary

Nested classes

interface DnsResolver.Callback<T>

Base interface for answer callbacks 

class DnsResolver.DnsException

Class to represent DNS error 

Constants

int CLASS_IN

int ERROR_PARSE

Indicates that there was an error parsing the response the query.

int ERROR_SYSTEM

Indicates that there was an error sending the query.

int FLAG_EMPTY

int FLAG_NO_CACHE_LOOKUP

int FLAG_NO_CACHE_STORE

int FLAG_NO_RETRY

int HTTPS_QUERY_WAIT_AUTO

Indicates that the default wait time should be used for the HTTPS query.

int HTTPS_QUERY_WAIT_NONE

Indicates that no additional wait should be used for the HTTPS query.

int HTTPS_QUERY_WAIT_UNTIL_TIMEOUT

Indicates that the HTTPS query will be retransmitted until it gets a response, or until it times out.

int TYPE_A

int TYPE_AAAA

int TYPE_HTTPS

Public methods

static DnsResolver getInstance(Context context, Looper looper)

Returns a DnsResolver instance.

static DnsResolver getInstance()

This method is deprecated. Use getInstance(Context,Looper) instead.

void query(Network network, String domain, int flags, Executor executor, int httpsTimeoutMillis, CancellationSignal cancellationSignal, Callback<HttpsEndpoint> callback)

Send concurrent A/AAAA/HTTPS DNS queries with the specified name on a network.

void query(Network network, String domain, int flags, Executor executor, CancellationSignal cancellationSignal, Callback<? super List<InetAddress>> callback)

Send a DNS query with the specified name on a network with both IPv4 and IPv6, get back a set of InetAddresses with rfc6724 sorting asynchronously.

void query(Network network, String domain, int nsType, int flags, Executor executor, CancellationSignal cancellationSignal, Callback<? super List<InetAddress>> callback)

Send a DNS query with the specified name and query type, get back a set of InetAddresses with rfc6724 sorting asynchronously.

void rawQuery(Network network, byte[] query, int flags, Executor executor, CancellationSignal cancellationSignal, Callback<? super byte[]> callback)

Send a raw DNS query.

void rawQuery(Network network, String domain, int nsClass, int nsType, int flags, Executor executor, CancellationSignal cancellationSignal, Callback<? super byte[]> callback)

Send a DNS query with the specified name, class and query type.

Inherited methods

Constants

CLASS_IN

Added in API level 29 
public static final int CLASS_IN

Constant Value: 1 (0x00000001)

ERROR_PARSE

Added in API level 29 
public static final int ERROR_PARSE

Indicates that there was an error parsing the response the query. The cause of this error is available via getCause() and is a ParseException.

Constant Value: 0 (0x00000000)

ERROR_SYSTEM

Added in API level 29 
public static final int ERROR_SYSTEM

Indicates that there was an error sending the query. The cause of this error is available via getCause() and is an ErrnoException.

Constant Value: 1 (0x00000001)

FLAG_EMPTY

Added in API level 29 
public static final int FLAG_EMPTY

Constant Value: 0 (0x00000000)

FLAG_NO_CACHE_LOOKUP

Added in API level 29 
public static final int FLAG_NO_CACHE_LOOKUP

Constant Value: 4 (0x00000004)

FLAG_NO_CACHE_STORE

Added in API level 29 
public static final int FLAG_NO_CACHE_STORE

Constant Value: 2 (0x00000002)

FLAG_NO_RETRY

Added in API level 29 
public static final int FLAG_NO_RETRY

Constant Value: 1 (0x00000001)

HTTPS_QUERY_WAIT_AUTO

Added in API level 29 
public static final int HTTPS_QUERY_WAIT_AUTO

Indicates that the default wait time should be used for the HTTPS query.

This option balances the extra latency of waiting for the HTTPS record with the latency and security benefits of receiving it.

Constant Value: -1 (0xffffffff)

HTTPS_QUERY_WAIT_NONE

Added in API level 29 
public static final int HTTPS_QUERY_WAIT_NONE

Indicates that no additional wait should be used for the HTTPS query.

This option means the callback will be called immediately as soon as the IP address queries have received a response, regardless of whether the HTTPS query has received a response or not.

This option is not recommended for security or latency because it may result in HTTPS records not being returned even if they exist.

Constant Value: 0 (0x00000000)

HTTPS_QUERY_WAIT_UNTIL_TIMEOUT

Added in API level 29 
public static final int HTTPS_QUERY_WAIT_UNTIL_TIMEOUT

Indicates that the HTTPS query will be retransmitted until it gets a response, or until it times out.

This option may increase latency if the HTTPS query is dropped by the network.

Constant Value: -2 (0xfffffffe)

TYPE_A

Added in API level 29 
public static final int TYPE_A

Constant Value: 1 (0x00000001)

TYPE_AAAA

Added in API level 29 
public static final int TYPE_AAAA

Constant Value: 28 (0x0000001c)

TYPE_HTTPS

Added in API level 29 
public static final int TYPE_HTTPS

Constant Value: 65 (0x00000041)

Public methods

getInstance

Added in API level 29 
public static DnsResolver getInstance (Context context, 
                Looper looper)

Returns a DnsResolver instance.

Parameters
context Context: used for internal interactions with other system services.
This value cannot be null.
looper Looper: Looper for monitoring incoming replies to DNS queries. If null, then uses the value returned by Looper.getMainLooper().
Returns
DnsResolver This value cannot be null.

getInstance

Added in API level 29 
public static DnsResolver getInstance ()

This method is deprecated.
Use getInstance(Context,Looper) instead.

Get instance for DnsResolver

Returns
DnsResolver This value cannot be null.

query

Added in API level 29 
public void query (Network network, 
                String domain, 
                int flags, 
                Executor executor, 
                int httpsTimeoutMillis, 
                CancellationSignal cancellationSignal, 
                Callback<HttpsEndpoint> callback)

Send concurrent A/AAAA/HTTPS DNS queries with the specified name on a network. The answer to all queries will be provided asynchronously through the provided callback Callback, which provides a HttpsEndpoint.

Parameters
network Network: Network specifying which network to query on. null for query on default network.
domain String: domain name to query.
This value cannot be null.
flags int: flags as a combination of the FLAGS_* constants.
Value is one of the following:
executor Executor: The Executor that the callback should be executed on.
This value cannot be null.
Callback and listener events are dispatched through this Executor, providing an easy way to control which thread is used. To dispatch events through the main thread of your application, you can use Context.getMainExecutor(). Otherwise, provide an Executor that dispatches to an appropriate thread.
httpsTimeoutMillis int: the timeout in milliseconds to wait for the HTTPS query to complete after the A/AAAA queries have already completed. May be set to HTTPS_QUERY_WAIT_NONE to disable any additional wait, HTTPS_QUERY_WAIT_AUTO to use the default wait time, HTTPS_QUERY_WAIT_UNTIL_TIMEOUT to wait for the HTTPS query to complete, or a specific value in milliseconds.
cancellationSignal CancellationSignal: used by the caller to signal if all the queries should be cancelled. May be null.
callback Callback: a Callback which will be called to notify the caller of the results of the A/AAAA/HTTPS DNS queries. Will return a ERROR_PARSE if any of the DNS records cannot be parsed, and should be treated as a resolution failure.
This value cannot be null.

query

Added in API level 29 
public void query (Network network, 
                String domain, 
                int flags, 
                Executor executor, 
                CancellationSignal cancellationSignal, 
                Callback<? super List<InetAddress>> callback)

Send a DNS query with the specified name on a network with both IPv4 and IPv6, get back a set of InetAddresses with rfc6724 sorting asynchronously. This method will examine the connection ability on given network, and query IPv4 and IPv6 if connection is available. This method will send A queries if the specified Network provides IPv4 connectivity, and AAAA queries if it provides IPv6 connectivity. If at least one query succeeded with valid answer, rcode will be 0 The answer will be provided asynchronously through the provided Callback.

Parameters
network Network: Network specifying which network to query on. null for query on default network.
domain String: domain name to query.
This value cannot be null.
flags int: flags as a combination of the FLAGS_* constants.
Value is one of the following:
executor Executor: The Executor that the callback should be executed on.
This value cannot be null.
Callback and listener events are dispatched through this Executor, providing an easy way to control which thread is used. To dispatch events through the main thread of your application, you can use Context.getMainExecutor(). Otherwise, provide an Executor that dispatches to an appropriate thread.
cancellationSignal CancellationSignal: used by the caller to signal if the query should be cancelled. May be null.
callback Callback: a Callback which will be called to notify the caller of the result of dns query.
This value cannot be null.

query

Added in API level 29 
public void query (Network network, 
                String domain, 
                int nsType, 
                int flags, 
                Executor executor, 
                CancellationSignal cancellationSignal, 
                Callback<? super List<InetAddress>> callback)

Send a DNS query with the specified name and query type, get back a set of InetAddresses with rfc6724 sorting asynchronously. The answer will be provided asynchronously through the provided Callback.

Parameters
network Network: Network specifying which network to query on. null for query on default network.
domain String: domain name to query.
This value cannot be null.
nsType int: dns resource record (RR) type as one of the TYPE_* constants.
Value is one of the following:
flags int: flags as a combination of the FLAGS_* constants.
Value is one of the following:
executor Executor: The Executor that the callback should be executed on.
This value cannot be null.
Callback and listener events are dispatched through this Executor, providing an easy way to control which thread is used. To dispatch events through the main thread of your application, you can use Context.getMainExecutor(). Otherwise, provide an Executor that dispatches to an appropriate thread.
cancellationSignal CancellationSignal: used by the caller to signal if the query should be cancelled. May be null.
callback Callback: a Callback which will be called to notify the caller of the result of dns query.
This value cannot be null.

rawQuery

Added in API level 29 
public void rawQuery (Network network, 
                byte[] query, 
                int flags, 
                Executor executor, 
                CancellationSignal cancellationSignal, 
                Callback<? super byte[]> callback)

Send a raw DNS query. The answer will be provided asynchronously through the provided Callback.

Parameters
network Network: Network specifying which network to query on. null for query on default network.
query byte: blob message to query.
This value cannot be null.
flags int: flags as a combination of the FLAGS_* constants.
Value is one of the following:
executor Executor: The Executor that the callback should be executed on.
This value cannot be null.
Callback and listener events are dispatched through this Executor, providing an easy way to control which thread is used. To dispatch events through the main thread of your application, you can use Context.getMainExecutor(). Otherwise, provide an Executor that dispatches to an appropriate thread.
cancellationSignal CancellationSignal: used by the caller to signal if the query should be cancelled. May be null.
callback Callback: a Callback which will be called to notify the caller of the result of dns query.
This value cannot be null.

rawQuery

Added in API level 29 
public void rawQuery (Network network, 
                String domain, 
                int nsClass, 
                int nsType, 
                int flags, 
                Executor executor, 
                CancellationSignal cancellationSignal, 
                Callback<? super byte[]> callback)

Send a DNS query with the specified name, class and query type. The answer will be provided asynchronously through the provided Callback.

Parameters
network Network: Network specifying which network to query on. null for query on default network.
domain String: domain name to query.
This value cannot be null.
nsClass int: dns class as one of the CLASS_* constants.
Value is one of the following:
nsType int: dns resource record (RR) type as one of the TYPE_* constants.
Value is one of the following:
flags int: flags as a combination of the FLAGS_* constants.
Value is one of the following:
executor Executor: The Executor that the callback should be executed on.
This value cannot be null.
Callback and listener events are dispatched through this Executor, providing an easy way to control which thread is used. To dispatch events through the main thread of your application, you can use Context.getMainExecutor(). Otherwise, provide an Executor that dispatches to an appropriate thread.
cancellationSignal CancellationSignal: used by the caller to signal if the query should be cancelled. May be null.
callback Callback: a Callback which will be called to notify the caller of the result of dns query.
This value cannot be null.