resolv/resolv_params.h

/*
 * Copyright (C) 2016 The Android Open Source Project
 *
 * 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.
 */

#ifndef _RESOLV_PARAMS_H
#define _RESOLV_PARAMS_H

#include <stdint.h>

/* Hard-coded defines */
#define MAXNS 4           /* max # name servers we'll track */
#define MAXDNSRCH 6       /* max # domains in search path */
#define MAXDNSRCHPATH 256 /* max length of domain search paths */
#define MAXNSSAMPLES 64   /* max # samples to store per server */

/* Defaults used for initializing __res_params */
#define SUCCESS_THRESHOLD                                 \
    75 /* if successes * 100 / total_samples is less than \
        * this value, the server is considered failing    \
        */
#define NSSAMPLE_VALIDITY                         \
    1800 /* Sample validity in seconds.           \
          * Set to -1 to disable skipping failing \
          * servers.                              \
          */

/* If EDNS0_PADDING is defined, queries will be padded to a multiple of this length
when EDNS0 is active. */
#define EDNS0_PADDING 128

/* per-netid configuration parameters passed from netd to the resolver */
struct __res_params {
    uint16_t sample_validity;  // sample lifetime in s
    // threshold of success / total samples below which a server is considered broken
    uint8_t success_threshold;  // 0: disable, value / 100 otherwise
    uint8_t min_samples;        // min # samples needed for statistics to be considered meaningful
    uint8_t max_samples;        // max # samples taken into account for statistics
    int base_timeout_msec;      // base query retry timeout (if 0, use RES_TIMEOUT)
};

typedef enum { res_goahead, res_nextns, res_modified, res_done, res_error } res_sendhookact;

typedef res_sendhookact (*res_send_qhook)(struct sockaddr* const*, const u_char**, int*, u_char*,
                                          int, int*);

typedef res_sendhookact (*res_send_rhook)(const struct sockaddr*, const u_char*, int, u_char*, int,
                                          int*);

#define LIBNETD_RESOLV_PUBLIC extern "C" [[gnu::visibility("default")]]

#endif  // _RESOLV_PARAMS_H