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/*
* Copyright 2015 The gRPC Authors
*
* Licensed 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.grpc.internal;
import com.google.common.base.Preconditions;
import com.google.common.base.Stopwatch;
import io.grpc.Attributes;
import io.grpc.NameResolverProvider;
import java.net.URI;
/**
* A provider for {@link DnsNameResolver}.
*
* <p>It resolves a target URI whose scheme is {@code "dns"}. The (optional) authority of the target
* URI is reserved for the address of alternative DNS server (not implemented yet). The path of the
* target URI, excluding the leading slash {@code '/'}, is treated as the host name and the optional
* port to be resolved by DNS. Example target URIs:
*
* <ul>
* <li>{@code "dns:///foo.googleapis.com:8080"} (using default DNS)</li>
* <li>{@code "dns://8.8.8.8/foo.googleapis.com:8080"} (using alternative DNS (not implemented
* yet))</li>
* <li>{@code "dns:///foo.googleapis.com"} (without port)</li>
* </ul>
*/
public final class DnsNameResolverProvider extends NameResolverProvider {
private static final String SCHEME = "dns";
@Override
public DnsNameResolver newNameResolver(URI targetUri, Attributes params) {
if (SCHEME.equals(targetUri.getScheme())) {
String targetPath = Preconditions.checkNotNull(targetUri.getPath(), "targetPath");
Preconditions.checkArgument(targetPath.startsWith("/"),
"the path component (%s) of the target (%s) must start with '/'", targetPath, targetUri);
String name = targetPath.substring(1);
return new DnsNameResolver(
targetUri.getAuthority(),
name,
params,
GrpcUtil.SHARED_CHANNEL_EXECUTOR,
GrpcUtil.getDefaultProxyDetector(),
Stopwatch.createUnstarted());
} else {
return null;
}
}
@Override
public String getDefaultScheme() {
return SCHEME;
}
@Override
protected boolean isAvailable() {
return true;
}
@Override
protected int priority() {
return 5;
}
}
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