85 lines
2.9 KiB
C
85 lines
2.9 KiB
C
/*
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* Copyright (C) 2016 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef _RES_STATS_H
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#define _RES_STATS_H
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#include <sys/socket.h>
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#include <stdbool.h>
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#include <stdint.h>
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#include <time.h>
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#include "resolv_params.h"
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#define RCODE_INTERNAL_ERROR 254
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#define RCODE_TIMEOUT 255
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/*
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* Resolver reachability statistics and run-time parameters.
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*/
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struct __res_sample {
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time_t at; // time in s at which the sample was recorded
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uint16_t rtt; // round-trip time in ms
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uint8_t rcode; // the DNS rcode or RCODE_XXX defined above
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};
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struct __res_stats {
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// Stats of the last <sample_count> queries.
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struct __res_sample samples[MAXNSSAMPLES];
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// The number of samples stored.
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uint8_t sample_count;
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// The next sample to modify.
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uint8_t sample_next;
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};
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/* Calculate the round-trip-time from start time t0 and end time t1. */
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extern int
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_res_stats_calculate_rtt(const struct timespec* t1, const struct timespec* t0);
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/* Initialize a sample for calculating server reachability statistics. */
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extern void
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_res_stats_set_sample(struct __res_sample* sample, time_t now, int rcode, int rtt);
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/* Returns true if the server is considered unusable, i.e. if the success rate is not lower than the
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* threshold for the stored stored samples. If not enough samples are stored, the server is
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* considered usable.
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*/
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extern bool
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_res_stats_usable_server(const struct __res_params* params, struct __res_stats* stats);
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__BEGIN_DECLS
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/* Aggregates the reachability statistics for the given server based on on the stored samples. */
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extern void
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android_net_res_stats_aggregate(struct __res_stats* stats, int* successes, int* errors,
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int* timeouts, int* internal_errors, int* rtt_avg, time_t* last_sample_time)
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__attribute__((visibility ("default")));
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extern int
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android_net_res_stats_get_info_for_net(unsigned netid, int* nscount,
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struct sockaddr_storage servers[MAXNS], int* dcount, char domains[MAXDNSRCH][MAXDNSRCHPATH],
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struct __res_params* params, struct __res_stats stats[MAXNS])
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__attribute__((visibility ("default")));
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/* Returns an array of bools indicating which servers are considered good */
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extern void
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android_net_res_stats_get_usable_servers(const struct __res_params* params,
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struct __res_stats stats[], int nscount, bool valid_servers[])
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__attribute__((visibility ("default")));
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__END_DECLS
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#endif // _RES_STATS_H
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