resolv_params.h revision 6b3f0d65f2c706625e5efb495df0f2c6178b965a 
1/*
2 * Copyright (C) 2016 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef _RESOLV_PARAMS_H
18#define _RESOLV_PARAMS_H
19
20#include <stdint.h>
21
22/* Hard-coded defines */
23#define	MAXNS			3	/* max # name servers we'll track */
24#define	MAXNSSAMPLES		64	/* max # samples to store per server */
25
26/* Defaults used for initializing __res_params */
27#define SUCCESS_THRESHOLD       75      /* if successes * 100 / total_samples is less than
28					 * this value, the server is considered failing
29					 */
30#define NSSAMPLE_VALIDITY	1800	/* Sample validity in seconds.
31					 * Set to -1 to disable skipping failing
32					 * servers.
33					 */
34
35/* per-netid configuration parameters passed from netd to the resolver */
36struct __res_params {
37    uint16_t sample_validity; // sample lifetime in s
38    // threshold of success / total samples below which a server is considered broken
39    uint8_t success_threshold; // 0: disable, value / 100 otherwise
40    uint8_t min_samples; // min # samples needed for statistics to be considered meaningful
41    uint8_t max_samples; // max # samples taken into account for statistics
42} __attribute__((__packed__));
43
44#endif // _RESOLV_PARAMS_H
45