/*
* Copyright 2015 The Netty Project
*
* The Netty Project licenses this file to you under the Apache License,
* version 2.0 (the "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*/
package io.netty.resolver.dns;
import io.netty.channel.ChannelFactory;
import io.netty.channel.EventLoop;
import io.netty.channel.ReflectiveChannelFactory;
import io.netty.channel.socket.DatagramChannel;
import io.netty.channel.socket.InternetProtocolFamily;
import io.netty.resolver.HostsFileEntriesResolver;
import io.netty.resolver.ResolvedAddressTypes;
import io.netty.util.internal.UnstableApi;
import java.util.ArrayList;
import java.util.List;
import static io.netty.resolver.dns.DnsServerAddressStreamProviders.platformDefault;
import static io.netty.util.internal.ObjectUtil.checkNotNull;
import static io.netty.util.internal.ObjectUtil.intValue;
/**
* A {@link DnsNameResolver} builder.
*/
@UnstableApi
public final class DnsNameResolverBuilder {
private final EventLoop eventLoop;
private ChannelFactory<? extends DatagramChannel> channelFactory;
private DnsCache resolveCache;
private DnsCache authoritativeDnsServerCache;
private Integer minTtl;
private Integer maxTtl;
private Integer negativeTtl;
private long queryTimeoutMillis = 5000;
private ResolvedAddressTypes resolvedAddressTypes = DnsNameResolver.DEFAULT_RESOLVE_ADDRESS_TYPES;
private boolean recursionDesired = true;
private int maxQueriesPerResolve = 16;
private boolean traceEnabled;
private int maxPayloadSize = 4096;
private boolean optResourceEnabled = true;
private HostsFileEntriesResolver hostsFileEntriesResolver = HostsFileEntriesResolver.DEFAULT;
private DnsServerAddressStreamProvider dnsServerAddressStreamProvider = platformDefault();
private DnsQueryLifecycleObserverFactory dnsQueryLifecycleObserverFactory =
NoopDnsQueryLifecycleObserverFactory.INSTANCE;
private String[] searchDomains = DnsNameResolver.DEFAULT_SEARCH_DOMAINS;
private int ndots = 1;
private boolean decodeIdn = true;
/**
* Creates a new builder.
*
* @param eventLoop the {@link EventLoop} the {@link EventLoop} which will perform the communication with the DNS
* servers.
*/
public DnsNameResolverBuilder(EventLoop eventLoop) {
this.eventLoop = eventLoop;
}
/**
* Sets the {@link ChannelFactory} that will create a {@link DatagramChannel}.
*
* @param channelFactory the {@link ChannelFactory}
* @return {@code this}
*/
public DnsNameResolverBuilder channelFactory(ChannelFactory<? extends DatagramChannel> channelFactory) {
this.channelFactory = channelFactory;
return this;
}
/**
* Sets the {@link ChannelFactory} as a {@link ReflectiveChannelFactory} of this type.
* Use as an alternative to {@link #channelFactory(ChannelFactory)}.
*
* @param channelType the type
* @return {@code this}
*/
public DnsNameResolverBuilder channelType(Class<? extends DatagramChannel> channelType) {
return channelFactory(new ReflectiveChannelFactory<DatagramChannel>(channelType));
}
/**
* Sets the cache for resolution results.
*
* @param resolveCache the DNS resolution results cache
* @return {@code this}
*/
public DnsNameResolverBuilder resolveCache(DnsCache resolveCache) {
this.resolveCache = resolveCache;
return this;
}
/**
* Set the factory used to generate objects which can observe individual DNS queries.
* @param lifecycleObserverFactory the factory used to generate objects which can observe individual DNS queries.
* @return {@code this}
*/
public DnsNameResolverBuilder dnsQueryLifecycleObserverFactory(DnsQueryLifecycleObserverFactory
lifecycleObserverFactory) {
this.dnsQueryLifecycleObserverFactory = checkNotNull(lifecycleObserverFactory, "lifecycleObserverFactory");
return this;
}
/**
* Sets the cache for authoritative NS servers
*
* @param authoritativeDnsServerCache the authoritative NS servers cache
* @return {@code this}
*/
public DnsNameResolverBuilder authoritativeDnsServerCache(DnsCache authoritativeDnsServerCache) {
this.authoritativeDnsServerCache = authoritativeDnsServerCache;
return this;
}
/**
* 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 {@code 0} and {@link Integer#MAX_VALUE}, which practically tells this resolver to
* respect the TTL from the DNS server.
*
* @param minTtl the minimum TTL
* @param maxTtl the maximum TTL
* @return {@code this}
*/
public DnsNameResolverBuilder ttl(int minTtl, int maxTtl) {
this.maxTtl = maxTtl;
this.minTtl = minTtl;
return this;
}
/**
* Sets the TTL of the cache for the failed DNS queries (in seconds).
*
* @param negativeTtl the TTL for failed cached queries
* @return {@code this}
*/
public DnsNameResolverBuilder negativeTtl(int negativeTtl) {
this.negativeTtl = negativeTtl;
return this;
}
/**
* Sets the timeout of each DNS query performed by this resolver (in milliseconds).
*
* @param queryTimeoutMillis the query timeout
* @return {@code this}
*/
public DnsNameResolverBuilder queryTimeoutMillis(long queryTimeoutMillis) {
this.queryTimeoutMillis = queryTimeoutMillis;
return this;
}
/**
* Compute a {@link ResolvedAddressTypes} from some {@link InternetProtocolFamily}s.
* An empty input will return the default value, based on "java.net" System properties.
* Valid inputs are (), (IPv4), (IPv6), (Ipv4, IPv6) and (IPv6, IPv4).
* @param internetProtocolFamilies a valid sequence of {@link InternetProtocolFamily}s
* @return a {@link ResolvedAddressTypes}
*/
public static ResolvedAddressTypes computeResolvedAddressTypes(InternetProtocolFamily... internetProtocolFamilies) {
if (internetProtocolFamilies == null || internetProtocolFamilies.length == 0) {
return DnsNameResolver.DEFAULT_RESOLVE_ADDRESS_TYPES;
}
if (internetProtocolFamilies.length > 2) {
throw new IllegalArgumentException("No more than 2 InternetProtocolFamilies");
}
switch(internetProtocolFamilies[0]) {
case IPv4:
return (internetProtocolFamilies.length >= 2
&& internetProtocolFamilies[1] == InternetProtocolFamily.IPv6) ?
ResolvedAddressTypes.IPV4_PREFERRED: ResolvedAddressTypes.IPV4_ONLY;
case IPv6:
return (internetProtocolFamilies.length >= 2
&& internetProtocolFamilies[1] == InternetProtocolFamily.IPv4) ?
ResolvedAddressTypes.IPV6_PREFERRED: ResolvedAddressTypes.IPV6_ONLY;
default:
throw new IllegalArgumentException(
"Couldn't resolve ResolvedAddressTypes from InternetProtocolFamily array");
}
}
/**
* Sets the list of the protocol families of the address resolved.
* You can use {@link DnsNameResolverBuilder#computeResolvedAddressTypes(InternetProtocolFamily...)}
* to get a {@link ResolvedAddressTypes} out of some {@link InternetProtocolFamily}s.
*
* @param resolvedAddressTypes the address types
* @return {@code this}
*/
public DnsNameResolverBuilder resolvedAddressTypes(ResolvedAddressTypes resolvedAddressTypes) {
this.resolvedAddressTypes = resolvedAddressTypes;
return this;
}
/**
* Sets if this resolver has to send a DNS query with the RD (recursion desired) flag set.
*
* @param recursionDesired true if recursion is desired
* @return {@code this}
*/
public DnsNameResolverBuilder recursionDesired(boolean recursionDesired) {
this.recursionDesired = recursionDesired;
return this;
}
/**
* Sets the maximum allowed number of DNS queries to send when resolving a host name.
*
* @param maxQueriesPerResolve the max number of queries
* @return {@code this}
*/
public DnsNameResolverBuilder maxQueriesPerResolve(int maxQueriesPerResolve) {
this.maxQueriesPerResolve = maxQueriesPerResolve;
return this;
}
/**
* 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.
*
* @param traceEnabled true if trace is enabled
* @return {@code this}
*/
public DnsNameResolverBuilder traceEnabled(boolean traceEnabled) {
this.traceEnabled = traceEnabled;
return this;
}
/**
* Sets the capacity of the datagram packet buffer (in bytes). The default value is {@code 4096} bytes.
*
* @param maxPayloadSize the capacity of the datagram packet buffer
* @return {@code this}
*/
public DnsNameResolverBuilder maxPayloadSize(int maxPayloadSize) {
this.maxPayloadSize = maxPayloadSize;
return this;
}
/**
* Enable 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. Some DNSServer may not support this and so fail to answer
* queries. If you find problems you may want to disable this.
*
* @param optResourceEnabled if optional records inclusion is enabled
* @return {@code this}
*/
public DnsNameResolverBuilder optResourceEnabled(boolean optResourceEnabled) {
this.optResourceEnabled = optResourceEnabled;
return this;
}
/**
* @param hostsFileEntriesResolver the {@link HostsFileEntriesResolver} used to first check
* if the hostname is locally aliased.
* @return {@code this}
*/
public DnsNameResolverBuilder hostsFileEntriesResolver(HostsFileEntriesResolver hostsFileEntriesResolver) {
this.hostsFileEntriesResolver = hostsFileEntriesResolver;
return this;
}
/**
* Set the {@link DnsServerAddressStreamProvider} which is used to determine which DNS server is used to resolve
* each hostname.
* @return {@code this}.
*/
public DnsNameResolverBuilder nameServerProvider(DnsServerAddressStreamProvider dnsServerAddressStreamProvider) {
this.dnsServerAddressStreamProvider =
checkNotNull(dnsServerAddressStreamProvider, "dnsServerAddressStreamProvider");
return this;
}
/**
* Set the list of search domains of the resolver.
*
* @param searchDomains the search domains
* @return {@code this}
*/
public DnsNameResolverBuilder searchDomains(Iterable<String> searchDomains) {
checkNotNull(searchDomains, "searchDomains");
final List<String> list = new ArrayList<String>(4);
for (String f : searchDomains) {
if (f == null) {
break;
}
// Avoid duplicate entries.
if (list.contains(f)) {
continue;
}
list.add(f);
}
this.searchDomains = list.toArray(new String[list.size()]);
return this;
}
/**
* Set the number of dots which must appear in a name before an initial absolute query is made.
* The default value is {@code 1}.
*
* @param ndots the ndots value
* @return {@code this}
*/
public DnsNameResolverBuilder ndots(int ndots) {
this.ndots = ndots;
return this;
}
private DnsCache newCache() {
return new DefaultDnsCache(intValue(minTtl, 0), intValue(maxTtl, Integer.MAX_VALUE), intValue(negativeTtl, 0));
}
/**
* Set if domain / host names should be decoded to unicode when received.
* See <a href="https://tools.ietf.org/html/rfc3492">rfc3492</a>.
*
* @param decodeIdn if should get decoded
* @return {@code this}
*/
public DnsNameResolverBuilder decodeIdn(boolean decodeIdn) {
this.decodeIdn = decodeIdn;
return this;
}
/**
* Returns a new {@link DnsNameResolver} instance.
*
* @return a {@link DnsNameResolver}
*/
public DnsNameResolver build() {
if (resolveCache != null && (minTtl != null || maxTtl != null || negativeTtl != null)) {
throw new IllegalStateException("resolveCache and TTLs are mutually exclusive");
}
if (authoritativeDnsServerCache != null && (minTtl != null || maxTtl != null || negativeTtl != null)) {
throw new IllegalStateException("authoritativeDnsServerCache and TTLs are mutually exclusive");
}
DnsCache resolveCache = this.resolveCache != null ? this.resolveCache : newCache();
DnsCache authoritativeDnsServerCache = this.authoritativeDnsServerCache != null ?
this.authoritativeDnsServerCache : newCache();
return new DnsNameResolver(
eventLoop,
channelFactory,
resolveCache,
authoritativeDnsServerCache,
dnsQueryLifecycleObserverFactory,
queryTimeoutMillis,
resolvedAddressTypes,
recursionDesired,
maxQueriesPerResolve,
traceEnabled,
maxPayloadSize,
optResourceEnabled,
hostsFileEntriesResolver,
dnsServerAddressStreamProvider,
searchDomains,
ndots,
decodeIdn);
}
}