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 _RES_STATS_H 18 #define _RES_STATS_H 19 20 #include <sys/socket.h> 21 #include <stdbool.h> 22 #include <stdint.h> 23 #include <time.h> 24 25 #include "resolv_params.h" 26 27 #define RCODE_INTERNAL_ERROR 254 28 #define RCODE_TIMEOUT 255 29 30 /* 31 * Resolver reachability statistics and run-time parameters. 32 */ 33 34 struct __res_sample { 35 time_t at; // time in s at which the sample was recorded 36 uint16_t rtt; // round-trip time in ms 37 uint8_t rcode; // the DNS rcode or RCODE_XXX defined above 38 }; 39 40 struct __res_stats { 41 // Stats of the last <sample_count> queries. 42 struct __res_sample samples[MAXNSSAMPLES]; 43 // The number of samples stored. 44 uint8_t sample_count; 45 // The next sample to modify. 46 uint8_t sample_next; 47 }; 48 49 /* Calculate the round-trip-time from start time t0 and end time t1. */ 50 extern int 51 _res_stats_calculate_rtt(const struct timespec* t1, const struct timespec* t0); 52 53 /* Initialize a sample for calculating server reachability statistics. */ 54 extern void 55 _res_stats_set_sample(struct __res_sample* sample, time_t now, int rcode, int rtt); 56 57 /* Returns true if the server is considered unusable, i.e. if the success rate is not lower than the 58 * threshold for the stored stored samples. If not enough samples are stored, the server is 59 * considered usable. 60 */ 61 extern bool 62 _res_stats_usable_server(const struct __res_params* params, struct __res_stats* stats); 63 64 __BEGIN_DECLS 65 /* Aggregates the reachability statistics for the given server based on on the stored samples. */ 66 extern void 67 android_net_res_stats_aggregate(struct __res_stats* stats, int* successes, int* errors, 68 int* timeouts, int* internal_errors, int* rtt_avg, time_t* last_sample_time) 69 __attribute__((visibility ("default"))); 70 71 extern int 72 android_net_res_stats_get_info_for_net(unsigned netid, int* nscount, 73 struct sockaddr_storage servers[MAXNS], int* dcount, char domains[MAXDNSRCH][MAXDNSRCHPATH], 74 struct __res_params* params, struct __res_stats stats[MAXNS]) 75 __attribute__((visibility ("default"))); 76 77 /* Returns an array of bools indicating which servers are considered good */ 78 extern void 79 android_net_res_stats_get_usable_servers(const struct __res_params* params, 80 struct __res_stats stats[], int nscount, bool valid_servers[]) 81 __attribute__((visibility ("default"))); 82 __END_DECLS 83 84 #endif // _RES_STATS_H 85