| /* |
| * 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 _RES_STATS_H |
| #define _RES_STATS_H |
| |
| #include <sys/socket.h> |
| #include <stdbool.h> |
| #include <stdint.h> |
| #include <time.h> |
| |
| #include "resolv_params.h" |
| |
| #define RCODE_INTERNAL_ERROR 254 |
| #define RCODE_TIMEOUT 255 |
| |
| /* |
| * Resolver reachability statistics and run-time parameters. |
| */ |
| |
| struct __res_sample { |
| time_t at; // time in s at which the sample was recorded |
| uint16_t rtt; // round-trip time in ms |
| uint8_t rcode; // the DNS rcode or RCODE_XXX defined above |
| }; |
| |
| struct __res_stats { |
| // Stats of the last <sample_count> queries. |
| struct __res_sample samples[MAXNSSAMPLES]; |
| // The number of samples stored. |
| uint8_t sample_count; |
| // The next sample to modify. |
| uint8_t sample_next; |
| }; |
| |
| /* Calculate the round-trip-time from start time t0 and end time t1. */ |
| extern int |
| _res_stats_calculate_rtt(const struct timespec* t1, const struct timespec* t0); |
| |
| /* Initialize a sample for calculating server reachability statistics. */ |
| extern void |
| _res_stats_set_sample(struct __res_sample* sample, time_t now, int rcode, int rtt); |
| |
| /* Returns true if the server is considered unusable, i.e. if the success rate is not lower than the |
| * threshold for the stored stored samples. If not enough samples are stored, the server is |
| * considered usable. |
| */ |
| extern bool |
| _res_stats_usable_server(const struct __res_params* params, struct __res_stats* stats); |
| |
| __BEGIN_DECLS |
| /* Aggregates the reachability statistics for the given server based on on the stored samples. */ |
| extern void |
| android_net_res_stats_aggregate(struct __res_stats* stats, int* successes, int* errors, |
| int* timeouts, int* internal_errors, int* rtt_avg, time_t* last_sample_time) |
| __attribute__((visibility ("default"))); |
| |
| extern int |
| android_net_res_stats_get_info_for_net(unsigned netid, int* nscount, |
| struct sockaddr_storage servers[MAXNS], int* dcount, char domains[MAXDNSRCH][MAXDNSRCHPATH], |
| struct __res_params* params, struct __res_stats stats[MAXNS]) |
| __attribute__((visibility ("default"))); |
| |
| /* Returns an array of bools indicating which servers are considered good */ |
| extern void |
| android_net_res_stats_get_usable_servers(const struct __res_params* params, |
| struct __res_stats stats[], int nscount, bool valid_servers[]) |
| __attribute__((visibility ("default"))); |
| __END_DECLS |
| |
| #endif // _RES_STATS_H |