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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "net/dns/host_resolver.h"
#include "base/logging.h"
#include "base/metrics/field_trial.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_split.h"
#include "base/values.h"
#include "net/base/net_errors.h"
#include "net/dns/dns_client.h"
#include "net/dns/host_cache.h"
#include "net/dns/host_resolver_impl.h"
namespace net {
namespace {
// Maximum of 6 concurrent resolver threads (excluding retries).
// Some routers (or resolvers) appear to start to provide host-not-found if
// too many simultaneous resolutions are pending. This number needs to be
// further optimized, but 8 is what FF currently does. We found some routers
// that limit this to 6, so we're temporarily holding it at that level.
const size_t kDefaultMaxProcTasks = 6u;
} // namespace
PrioritizedDispatcher::Limits HostResolver::Options::GetDispatcherLimits()
const {
PrioritizedDispatcher::Limits limits(NUM_PRIORITIES, max_concurrent_resolves);
// If not using default, do not use the field trial.
if (limits.total_jobs != HostResolver::kDefaultParallelism)
return limits;
// Default, without trial is no reserved slots.
limits.total_jobs = kDefaultMaxProcTasks;
// Parallelism is determined by the field trial.
std::string group = base::FieldTrialList::FindFullName(
"HostResolverDispatch");
if (group.empty())
return limits;
// The format of the group name is a list of non-negative integers separated
// by ':'. Each of the elements in the list corresponds to an element in
// |reserved_slots|, except the last one which is the |total_jobs|.
std::vector<base::StringPiece> group_parts = base::SplitStringPiece(
group, ":", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
if (group_parts.size() != NUM_PRIORITIES + 1) {
NOTREACHED();
return limits;
}
std::vector<size_t> parsed(group_parts.size());
size_t total_reserved_slots = 0;
for (size_t i = 0; i < group_parts.size(); ++i) {
if (!base::StringToSizeT(group_parts[i], &parsed[i])) {
NOTREACHED();
return limits;
}
}
size_t total_jobs = parsed.back();
parsed.pop_back();
for (size_t i = 0; i < parsed.size(); ++i) {
total_reserved_slots += parsed[i];
}
// There must be some unreserved slots available for the all priorities.
if (total_reserved_slots > total_jobs ||
(total_reserved_slots == total_jobs && parsed[MINIMUM_PRIORITY] == 0)) {
NOTREACHED();
return limits;
}
limits.total_jobs = total_jobs;
limits.reserved_slots = parsed;
return limits;
}
HostResolver::Options::Options()
: max_concurrent_resolves(kDefaultParallelism),
max_retry_attempts(kDefaultRetryAttempts),
enable_caching(true) {
}
HostResolver::RequestInfo::RequestInfo(const HostPortPair& host_port_pair)
: RequestInfo() {
host_port_pair_ = host_port_pair;
}
HostResolver::RequestInfo::RequestInfo(const RequestInfo& request_info) =
default;
HostResolver::RequestInfo::~RequestInfo() = default;
HostResolver::RequestInfo::RequestInfo()
: address_family_(ADDRESS_FAMILY_UNSPECIFIED),
host_resolver_flags_(0),
allow_cached_response_(true),
is_speculative_(false),
is_my_ip_address_(false) {}
HostResolver::~HostResolver() = default;
void HostResolver::SetDnsClientEnabled(bool enabled) {
}
HostCache* HostResolver::GetHostCache() {
return nullptr;
}
std::unique_ptr<base::Value> HostResolver::GetDnsConfigAsValue() const {
return nullptr;
}
void HostResolver::SetNoIPv6OnWifi(bool no_ipv6_on_wifi) {
NOTREACHED();
}
bool HostResolver::GetNoIPv6OnWifi() {
return false;
}
const std::vector<DnsConfig::DnsOverHttpsServerConfig>*
HostResolver::GetDnsOverHttpsServersForTesting() const {
return nullptr;
}
// static
std::unique_ptr<HostResolver> HostResolver::CreateSystemResolver(
const Options& options,
NetLog* net_log) {
return std::unique_ptr<HostResolver>(
CreateSystemResolverImpl(options, net_log).release());
}
// static
std::unique_ptr<HostResolverImpl> HostResolver::CreateSystemResolverImpl(
const Options& options,
NetLog* net_log) {
return std::make_unique<HostResolverImpl>(options, net_log);
}
// static
std::unique_ptr<HostResolver> HostResolver::CreateDefaultResolver(
NetLog* net_log) {
return CreateSystemResolver(Options(), net_log);
}
// static
std::unique_ptr<HostResolverImpl> HostResolver::CreateDefaultResolverImpl(
NetLog* net_log) {
return CreateSystemResolverImpl(Options(), net_log);
}
// static
AddressFamily HostResolver::DnsQueryTypeToAddressFamily(
DnsQueryType dns_query_type) {
switch (dns_query_type) {
case DnsQueryType::UNSPECIFIED:
return ADDRESS_FAMILY_UNSPECIFIED;
case DnsQueryType::A:
return ADDRESS_FAMILY_IPV4;
case DnsQueryType::AAAA:
return ADDRESS_FAMILY_IPV6;
default:
// |dns_query_type| should be an address type (A or AAAA) or UNSPECIFIED.
NOTREACHED();
return ADDRESS_FAMILY_UNSPECIFIED;
}
}
// static
HostResolver::DnsQueryType HostResolver::AddressFamilyToDnsQueryType(
AddressFamily address_family) {
switch (address_family) {
case ADDRESS_FAMILY_UNSPECIFIED:
return DnsQueryType::UNSPECIFIED;
case ADDRESS_FAMILY_IPV4:
return DnsQueryType::A;
case ADDRESS_FAMILY_IPV6:
return DnsQueryType::AAAA;
default:
NOTREACHED();
return DnsQueryType::UNSPECIFIED;
}
}
// static
HostResolver::ResolveHostParameters
HostResolver::RequestInfoToResolveHostParameters(
const HostResolver::RequestInfo& request_info,
RequestPriority priority) {
// Flag that should only be set internally, not used in input.
DCHECK(!(request_info.host_resolver_flags() &
HOST_RESOLVER_DEFAULT_FAMILY_SET_DUE_TO_NO_IPV6));
ResolveHostParameters parameters;
parameters.dns_query_type =
AddressFamilyToDnsQueryType(request_info.address_family());
parameters.initial_priority = priority;
parameters.source = FlagsToSource(request_info.host_resolver_flags());
parameters.allow_cached_response = request_info.allow_cached_response();
parameters.include_canonical_name =
request_info.host_resolver_flags() & HOST_RESOLVER_CANONNAME;
parameters.loopback_only =
request_info.host_resolver_flags() & HOST_RESOLVER_LOOPBACK_ONLY;
parameters.is_speculative = request_info.is_speculative();
return parameters;
}
// static
HostResolverSource HostResolver::FlagsToSource(HostResolverFlags flags) {
// To counter the lack of CNAME support in the async host resolver, SYSTEM is
// forced when CANONNAME flags is present. This restriction can be removed
// once CNAME support is added to the async resolver. See
// https://crbug.com/872665
//
// It is intentional that the presence of either flag forces SYSTEM.
if (flags & (HOST_RESOLVER_SYSTEM_ONLY | HOST_RESOLVER_CANONNAME))
return HostResolverSource::SYSTEM;
return HostResolverSource::ANY;
}
// static
HostResolverFlags HostResolver::ParametersToHostResolverFlags(
const ResolveHostParameters& parameters) {
HostResolverFlags flags = 0;
if (parameters.source == HostResolverSource::SYSTEM)
flags |= HOST_RESOLVER_SYSTEM_ONLY;
if (parameters.include_canonical_name)
flags |= HOST_RESOLVER_CANONNAME;
if (parameters.loopback_only)
flags |= HOST_RESOLVER_LOOPBACK_ONLY;
return flags;
}
HostResolver::HostResolver() = default;
} // namespace net