core/src/main/java/io/grpc/internal/CallCredentialsApplyingTransportFactory.java

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package io.grpc.internal;

import static com.google.common.base.MoreObjects.firstNonNull;
import static com.google.common.base.Preconditions.checkNotNull;

import io.grpc.Attributes;
import io.grpc.CallCredentials;
import io.grpc.CallOptions;
import io.grpc.Metadata;
import io.grpc.MethodDescriptor;
import io.grpc.SecurityLevel;

import java.net.SocketAddress;
import java.util.concurrent.Executor;
import javax.annotation.Nullable;

final class CallCredentialsApplyingTransportFactory implements ClientTransportFactory {
  private final ClientTransportFactory delegate;
  private final Executor appExecutor;

  CallCredentialsApplyingTransportFactory(
      ClientTransportFactory delegate, Executor appExecutor) {
    this.delegate = checkNotNull(delegate, "delegate");
    this.appExecutor = checkNotNull(appExecutor, "appExecutor");
  }

  @Override
  public ConnectionClientTransport newClientTransport(
      SocketAddress serverAddress, String authority, @Nullable String userAgent) {
    return new CallCredentialsApplyingTransport(
        delegate.newClientTransport(serverAddress, authority, userAgent), authority);
  }

  @Override
  public void close() {
    delegate.close();
  }

  private class CallCredentialsApplyingTransport extends ForwardingConnectionClientTransport {
    private final ConnectionClientTransport delegate;
    private final String authority;

    CallCredentialsApplyingTransport(ConnectionClientTransport delegate, String authority) {
      this.delegate = checkNotNull(delegate, "delegate");
      this.authority = checkNotNull(authority, "authority");
    }

    @Override
    protected ConnectionClientTransport delegate() {
      return delegate;
    }

    @Override
    public ClientStream newStream(
        MethodDescriptor<?, ?> method, Metadata headers, CallOptions callOptions,
        StatsTraceContext statsTraceCtx) {
      CallCredentials creds = callOptions.getCredentials();
      if (creds != null) {
        MetadataApplierImpl applier = new MetadataApplierImpl(
            delegate, method, headers, callOptions, statsTraceCtx);
        Attributes.Builder effectiveAttrsBuilder = Attributes.newBuilder()
            .set(CallCredentials.ATTR_AUTHORITY, authority)
            .set(CallCredentials.ATTR_SECURITY_LEVEL, SecurityLevel.NONE)
            .setAll(delegate.getAttributes());
        if (callOptions.getAuthority() != null) {
          effectiveAttrsBuilder.set(CallCredentials.ATTR_AUTHORITY, callOptions.getAuthority());
        }
        creds.applyRequestMetadata(method, effectiveAttrsBuilder.build(),
            firstNonNull(callOptions.getExecutor(), appExecutor), applier);
        return applier.returnStream();
      } else {
        return delegate.newStream(method, headers, callOptions, statsTraceCtx);
      }
    }
  }
}