/*
* Copyright (C) 2011 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.
*/
#define LOG_TAG "ResolverController"
#define DBG 0
#include <algorithm>
#include <cstdlib>
#include <string>
#include <vector>
#include <cutils/log.h>
#include <net/if.h>
#include <sys/socket.h>
#include <netdb.h>
// NOTE: <resolv_netid.h> is a private C library header that provides
// declarations for _resolv_set_nameservers_for_net and
// _resolv_flush_cache_for_net
#include <resolv_netid.h>
#include <resolv_params.h>
#include <resolv_stats.h>
#include <android-base/strings.h>
#include <android/net/INetd.h>
#include "DumpWriter.h"
#include "ResolverController.h"
#include "ResolverStats.h"
namespace android {
namespace net {
int ResolverController::setDnsServers(unsigned netId, const char* searchDomains,
const char** servers, int numservers, const __res_params* params) {
if (DBG) {
ALOGD("setDnsServers netId = %u\n", netId);
}
return -_resolv_set_nameservers_for_net(netId, servers, numservers, searchDomains, params);
}
int ResolverController::clearDnsServers(unsigned netId) {
_resolv_set_nameservers_for_net(netId, NULL, 0, "", NULL);
if (DBG) {
ALOGD("clearDnsServers netId = %u\n", netId);
}
return 0;
}
int ResolverController::flushDnsCache(unsigned netId) {
if (DBG) {
ALOGD("flushDnsCache netId = %u\n", netId);
}
_resolv_flush_cache_for_net(netId);
return 0;
}
int ResolverController::getDnsInfo(unsigned netId, std::vector<std::string>* servers,
std::vector<std::string>* domains, __res_params* params,
std::vector<android::net::ResolverStats>* stats) {
using android::net::ResolverStats;
using android::net::INetd;
static_assert(ResolverStats::STATS_SUCCESSES == INetd::RESOLVER_STATS_SUCCESSES &&
ResolverStats::STATS_ERRORS == INetd::RESOLVER_STATS_ERRORS &&
ResolverStats::STATS_TIMEOUTS == INetd::RESOLVER_STATS_TIMEOUTS &&
ResolverStats::STATS_INTERNAL_ERRORS == INetd::RESOLVER_STATS_INTERNAL_ERRORS &&
ResolverStats::STATS_RTT_AVG == INetd::RESOLVER_STATS_RTT_AVG &&
ResolverStats::STATS_LAST_SAMPLE_TIME == INetd::RESOLVER_STATS_LAST_SAMPLE_TIME &&
ResolverStats::STATS_USABLE == INetd::RESOLVER_STATS_USABLE &&
ResolverStats::STATS_COUNT == INetd::RESOLVER_STATS_COUNT,
"AIDL and ResolverStats.h out of sync");
int nscount = -1;
sockaddr_storage res_servers[MAXNS];
int dcount = -1;
char res_domains[MAXDNSRCH][MAXDNSRCHPATH];
__res_stats res_stats[MAXNS];
servers->clear();
domains->clear();
*params = __res_params{};
stats->clear();
int revision_id = android_net_res_stats_get_info_for_net(netId, &nscount, res_servers, &dcount,
res_domains, params, res_stats);
// If the netId is unknown (which can happen for valid net IDs for which no DNS servers have
// yet been configured), there is no revision ID. In this case there is no data to return.
if (revision_id < 0) {
return 0;
}
// Verify that the returned data is sane.
if (nscount < 0 || nscount > MAXNS || dcount < 0 || dcount > MAXDNSRCH) {
ALOGE("%s: nscount=%d, dcount=%d", __FUNCTION__, nscount, dcount);
return -ENOTRECOVERABLE;
}
// Determine which servers are considered usable by the resolver.
bool valid_servers[MAXNS];
std::fill_n(valid_servers, MAXNS, false);
android_net_res_stats_get_usable_servers(params, res_stats, nscount, valid_servers);
// Convert the server sockaddr structures to std::string.
stats->resize(nscount);
for (int i = 0 ; i < nscount ; ++i) {
char hbuf[NI_MAXHOST];
int rv = getnameinfo(reinterpret_cast<const sockaddr*>(&res_servers[i]),
sizeof(res_servers[i]), hbuf, sizeof(hbuf), nullptr, 0, NI_NUMERICHOST);
std::string server_str;
if (rv == 0) {
server_str.assign(hbuf);
} else {
ALOGE("getnameinfo() failed for server #%d: %s", i, gai_strerror(rv));
server_str.assign("<invalid>");
}
servers->push_back(std::move(server_str));
android::net::ResolverStats& cur_stats = (*stats)[i];
android_net_res_stats_aggregate(&res_stats[i], &cur_stats.successes, &cur_stats.errors,
&cur_stats.timeouts, &cur_stats.internal_errors, &cur_stats.rtt_avg,
&cur_stats.last_sample_time);
cur_stats.usable = valid_servers[i];
}
// Convert the stack-allocated search domain strings to std::string.
for (int i = 0 ; i < dcount ; ++i) {
domains->push_back(res_domains[i]);
}
return 0;
}
int ResolverController::setResolverConfiguration(int32_t netId,
const std::vector<std::string>& servers, const std::vector<std::string>& domains,
const std::vector<int32_t>& params) {
using android::net::INetd;
if (params.size() != INetd::RESOLVER_PARAMS_COUNT) {
ALOGE("%s: params.size()=%zu", __FUNCTION__, params.size());
return -EINVAL;
}
auto server_count = std::min<size_t>(MAXNS, servers.size());
std::vector<const char*> server_ptrs;
for (size_t i = 0 ; i < server_count ; ++i) {
server_ptrs.push_back(servers[i].c_str());
}
std::string domains_str;
if (!domains.empty()) {
domains_str = domains[0];
for (size_t i = 1 ; i < domains.size() ; ++i) {
domains_str += " " + domains[i];
}
}
__res_params res_params;
res_params.sample_validity = params[INetd::RESOLVER_PARAMS_SAMPLE_VALIDITY];
res_params.success_threshold = params[INetd::RESOLVER_PARAMS_SUCCESS_THRESHOLD];
res_params.min_samples = params[INetd::RESOLVER_PARAMS_MIN_SAMPLES];
res_params.max_samples = params[INetd::RESOLVER_PARAMS_MAX_SAMPLES];
return setDnsServers(netId, domains_str.c_str(), server_ptrs.data(), server_ptrs.size(),
&res_params);
}
int ResolverController::getResolverInfo(int32_t netId, std::vector<std::string>* servers,
std::vector<std::string>* domains, std::vector<int32_t>* params,
std::vector<int32_t>* stats) {
using android::net::ResolverStats;
using android::net::INetd;
__res_params res_params;
std::vector<ResolverStats> res_stats;
int ret = getDnsInfo(netId, servers, domains, &res_params, &res_stats);
if (ret != 0) {
return ret;
}
// Serialize the information for binder.
ResolverStats::encodeAll(res_stats, stats);
params->resize(INetd::RESOLVER_PARAMS_COUNT);
(*params)[INetd::RESOLVER_PARAMS_SAMPLE_VALIDITY] = res_params.sample_validity;
(*params)[INetd::RESOLVER_PARAMS_SUCCESS_THRESHOLD] = res_params.success_threshold;
(*params)[INetd::RESOLVER_PARAMS_MIN_SAMPLES] = res_params.min_samples;
(*params)[INetd::RESOLVER_PARAMS_MAX_SAMPLES] = res_params.max_samples;
return 0;
}
void ResolverController::dump(DumpWriter& dw, unsigned netId) {
// No lock needed since Bionic's resolver locks all accessed data structures internally.
using android::net::ResolverStats;
std::vector<std::string> servers;
std::vector<std::string> domains;
__res_params params;
std::vector<ResolverStats> stats;
time_t now = time(nullptr);
int rv = getDnsInfo(netId, &servers, &domains, ¶ms, &stats);
dw.incIndent();
if (rv != 0) {
dw.println("getDnsInfo() failed for netid %u", netId);
} else {
if (servers.empty()) {
dw.println("No DNS servers defined");
} else {
dw.println("DNS servers: # IP (total, successes, errors, timeouts, internal errors, "
"RTT avg, last sample)");
dw.incIndent();
for (size_t i = 0 ; i < servers.size() ; ++i) {
if (i < stats.size()) {
const ResolverStats& s = stats[i];
int total = s.successes + s.errors + s.timeouts + s.internal_errors;
if (total > 0) {
int time_delta = (s.last_sample_time > 0) ? now - s.last_sample_time : -1;
dw.println("%s (%d, %d, %d, %d, %d, %dms, %ds)%s", servers[i].c_str(),
total, s.successes, s.errors, s.timeouts, s.internal_errors,
s.rtt_avg, time_delta, s.usable ? "" : " BROKEN");
} else {
dw.println("%s <no data>", servers[i].c_str());
}
} else {
dw.println("%s <no stats>", servers[i].c_str());
}
}
dw.decIndent();
}
if (domains.empty()) {
dw.println("No search domains defined");
} else {
std::string domains_str = android::base::Join(domains, ", ");
dw.println("search domains: %s", domains_str.c_str());
}
if (params.sample_validity != 0) {
dw.println("DNS parameters: sample validity = %us, success threshold = %u%%, "
"samples (min, max) = (%u, %u)", params.sample_validity,
static_cast<unsigned>(params.success_threshold),
static_cast<unsigned>(params.min_samples),
static_cast<unsigned>(params.max_samples));
}
}
dw.decIndent();
}
} // namespace net
} // namespace android