Method interceptCall

xds/src/main/java/io/grpc/xds/RbacFilter.java:192–208

(
                final ServerCall<ReqT, RespT> call,
                final Metadata headers, ServerCallHandler<ReqT, RespT> next)

    final GrpcAuthorizationEngine authEngine = new GrpcAuthorizationEngine(config);
    return new ServerInterceptor() {
        @Override
        public <ReqT, RespT> ServerCall.Listener<ReqT> interceptCall(
                final ServerCall<ReqT, RespT> call,
                final Metadata headers, ServerCallHandler<ReqT, RespT> next) {
          AuthDecision authResult = authEngine.evaluate(headers, call);
          if (logger.isLoggable(Level.FINE)) {
            logger.log(Level.FINE,
                "Authorization result for serverCall {0}: {1}, matching policy: {2}.",
                new Object[]{call, authResult.decision(), authResult.matchingPolicyName()});
          }
          if (GrpcAuthorizationEngine.Action.DENY.equals(authResult.decision())) {
            Status status = Status.PERMISSION_DENIED.withDescription("Access Denied");
            call.close(status, new Metadata());
            return new ServerCall.Listener<ReqT>(){};
          }
          return next.startCall(call, headers);
        }
    };
  }