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chromium / chromium / src / 39ebf170c065db29bc79b65ca775f932617b48ed / . / net / dns / host_resolver_manager.cc
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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_manager.h"
#if defined(OS_WIN)
#include <Winsock2.h>
#elif defined(OS_POSIX) || defined(OS_FUCHSIA)
#include <netdb.h>
#include <netinet/in.h>
#if !defined(OS_NACL)
#include <net/if.h>
#if !defined(OS_ANDROID)
#include <ifaddrs.h>
#endif // !defined(OS_ANDROID)
#endif // !defined(OS_NACL)
#endif // defined(OS_WIN)
#include <algorithm>
#include <cmath>
#include <limits>
#include <memory>
#include <unordered_set>
#include <utility>
#include "base/bind.h"
#include "base/bind_helpers.h"
#include "base/callback.h"
#include "base/callback_helpers.h"
#include "base/compiler_specific.h"
#include "base/containers/linked_list.h"
#include "base/debug/debugger.h"
#include "base/logging.h"
#include "base/macros.h"
#include "base/memory/ptr_util.h"
#include "base/metrics/field_trial.h"
#include "base/metrics/field_trial_params.h"
#include "base/metrics/histogram_functions.h"
#include "base/metrics/histogram_macros.h"
#include "base/no_destructor.h"
#include "base/numerics/checked_math.h"
#include "base/rand_util.h"
#include "base/sequence_checker.h"
#include "base/single_thread_task_runner.h"
#include "base/strings/string_util.h"
#include "base/strings/utf_string_conversions.h"
#include "base/task/post_task.h"
#include "base/threading/scoped_blocking_call.h"
#include "base/threading/thread_task_runner_handle.h"
#include "base/time/default_tick_clock.h"
#include "base/time/time.h"
#include "base/trace_event/trace_event.h"
#include "base/values.h"
#include "build/build_config.h"
#include "net/base/address_family.h"
#include "net/base/address_list.h"
#include "net/base/host_port_pair.h"
#include "net/base/ip_address.h"
#include "net/base/ip_endpoint.h"
#include "net/base/net_errors.h"
#include "net/base/trace_constants.h"
#include "net/base/url_util.h"
#include "net/dns/address_sorter.h"
#include "net/dns/dns_client.h"
#include "net/dns/dns_reloader.h"
#include "net/dns/dns_response.h"
#include "net/dns/dns_transaction.h"
#include "net/dns/dns_util.h"
#include "net/dns/host_resolver_mdns_listener_impl.h"
#include "net/dns/host_resolver_mdns_task.h"
#include "net/dns/host_resolver_proc.h"
#include "net/dns/mdns_client.h"
#include "net/dns/public/dns_protocol.h"
#include "net/dns/record_parsed.h"
#include "net/log/net_log.h"
#include "net/log/net_log_capture_mode.h"
#include "net/log/net_log_event_type.h"
#include "net/log/net_log_parameters_callback.h"
#include "net/log/net_log_source.h"
#include "net/log/net_log_source_type.h"
#include "net/log/net_log_with_source.h"
#include "net/socket/client_socket_factory.h"
#include "net/socket/datagram_client_socket.h"
#include "url/url_canon_ip.h"
#if BUILDFLAG(ENABLE_MDNS)
#include "net/dns/mdns_client_impl.h"
#endif
#if defined(OS_WIN)
#include "net/base/winsock_init.h"
#endif
#if defined(OS_ANDROID)
#include "base/android/build_info.h"
#include "net/android/network_library.h"
#endif
namespace net {
namespace {
// Limit the size of hostnames that will be resolved to combat issues in
// some platform's resolvers.
const size_t kMaxHostLength = 4096;
// Default TTL for successful resolutions with ProcTask.
const unsigned kCacheEntryTTLSeconds = 60;
// Default TTL for unsuccessful resolutions with ProcTask.
const unsigned kNegativeCacheEntryTTLSeconds = 0;
// Minimum TTL for successful resolutions with DnsTask.
const unsigned kMinimumTTLSeconds = kCacheEntryTTLSeconds;
// Time between IPv6 probes, i.e. for how long results of each IPv6 probe are
// cached.
const int kIPv6ProbePeriodMs = 1000;
// Google DNS address used for IPv6 probes.
const uint8_t kIPv6ProbeAddress[] = {0x20, 0x01, 0x48, 0x60, 0x48, 0x60,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x88, 0x88};
enum DnsResolveStatus {
RESOLVE_STATUS_DNS_SUCCESS = 0,
RESOLVE_STATUS_PROC_SUCCESS,
RESOLVE_STATUS_FAIL,
RESOLVE_STATUS_SUSPECT_NETBIOS,
RESOLVE_STATUS_MAX
};
// ICANN uses this localhost address to indicate a name collision.
//
// The policy in Chromium is to fail host resolving if it resolves to
// this special address.
//
// Not however that IP literals are exempt from this policy, so it is still
// possible to navigate to http://127.0.53.53/ directly.
//
// For more details: https://www.icann.org/news/announcement-2-2014-08-01-en
const uint8_t kIcanNameCollisionIp[] = {127, 0, 53, 53};
bool ContainsIcannNameCollisionIp(const AddressList& addr_list) {
for (const auto& endpoint : addr_list) {
const IPAddress& addr = endpoint.address();
if (addr.IsIPv4() && IPAddressStartsWith(addr, kIcanNameCollisionIp)) {
return true;
}
}
return false;
}
// True if |hostname| ends with either ".local" or ".local.".
bool ResemblesMulticastDNSName(const std::string& hostname) {
DCHECK(!hostname.empty());
const char kSuffix[] = ".local.";
const size_t kSuffixLen = sizeof(kSuffix) - 1;
const size_t kSuffixLenTrimmed = kSuffixLen - 1;
if (hostname.back() == '.') {
return hostname.size() > kSuffixLen &&
!hostname.compare(hostname.size() - kSuffixLen, kSuffixLen, kSuffix);
}
return hostname.size() > kSuffixLenTrimmed &&
!hostname.compare(hostname.size() - kSuffixLenTrimmed,
kSuffixLenTrimmed, kSuffix, kSuffixLenTrimmed);
}
bool ConfigureAsyncDnsNoFallbackFieldTrial() {
const bool kDefault = false;
// Configure the AsyncDns field trial as follows:
// groups AsyncDnsNoFallbackA and AsyncDnsNoFallbackB: return true,
// groups AsyncDnsA and AsyncDnsB: return false,
// groups SystemDnsA and SystemDnsB: return false,
// otherwise (trial absent): return default.
std::string group_name = base::FieldTrialList::FindFullName("AsyncDns");
if (!group_name.empty()) {
return base::StartsWith(group_name, "AsyncDnsNoFallback",
base::CompareCase::INSENSITIVE_ASCII);
}
return kDefault;
}
const base::FeatureParam<base::TaskPriority>::Option prio_modes[] = {
{base::TaskPriority::USER_VISIBLE, "default"},
{base::TaskPriority::USER_BLOCKING, "user_blocking"}};
const base::Feature kSystemResolverPriorityExperiment = {
"SystemResolverPriorityExperiment", base::FEATURE_DISABLED_BY_DEFAULT};
const base::FeatureParam<base::TaskPriority> priority_mode{
&kSystemResolverPriorityExperiment, "mode",
base::TaskPriority::USER_VISIBLE, &prio_modes};
//-----------------------------------------------------------------------------
// Returns true if |addresses| contains only IPv4 loopback addresses.
bool IsAllIPv4Loopback(const AddressList& addresses) {
for (unsigned i = 0; i < addresses.size(); ++i) {
const IPAddress& address = addresses[i].address();
switch (addresses[i].GetFamily()) {
case ADDRESS_FAMILY_IPV4:
if (address.bytes()[0] != 127)
return false;
break;
case ADDRESS_FAMILY_IPV6:
return false;
default:
NOTREACHED();
return false;
}
}
return true;
}
// Returns true if it can determine that only loopback addresses are configured.
// i.e. if only 127.0.0.1 and ::1 are routable.
// Also returns false if it cannot determine this.
bool HaveOnlyLoopbackAddresses() {
base::ScopedBlockingCall scoped_blocking_call(FROM_HERE,
base::BlockingType::WILL_BLOCK);
#if defined(OS_WIN)
// TODO(wtc): implement with the GetAdaptersAddresses function.
NOTIMPLEMENTED();
return false;
#elif defined(OS_ANDROID)
return android::HaveOnlyLoopbackAddresses();
#elif defined(OS_NACL)
NOTIMPLEMENTED();
return false;
#elif defined(OS_POSIX) || defined(OS_FUCHSIA)
struct ifaddrs* interface_addr = NULL;
int rv = getifaddrs(&interface_addr);
if (rv != 0) {
DVPLOG(1) << "getifaddrs() failed";
return false;
}
bool result = true;
for (struct ifaddrs* interface = interface_addr; interface != NULL;
interface = interface->ifa_next) {
if (!(IFF_UP & interface->ifa_flags))
continue;
if (IFF_LOOPBACK & interface->ifa_flags)
continue;
const struct sockaddr* addr = interface->ifa_addr;
if (!addr)
continue;
if (addr->sa_family == AF_INET6) {
// Safe cast since this is AF_INET6.
const struct sockaddr_in6* addr_in6 =
reinterpret_cast<const struct sockaddr_in6*>(addr);
const struct in6_addr* sin6_addr = &addr_in6->sin6_addr;
if (IN6_IS_ADDR_LOOPBACK(sin6_addr) || IN6_IS_ADDR_LINKLOCAL(sin6_addr))
continue;
}
if (addr->sa_family != AF_INET6 && addr->sa_family != AF_INET)
continue;
result = false;
break;
}
freeifaddrs(interface_addr);
return result;
#endif // defined(various platforms)
}
// Creates NetLog parameters when the resolve failed.
std::unique_ptr<base::Value> NetLogProcTaskFailedCallback(
uint32_t attempt_number,
int net_error,
int os_error,
NetLogCaptureMode /* capture_mode */) {
std::unique_ptr<base::DictionaryValue> dict(new base::DictionaryValue());
if (attempt_number)
dict->SetInteger("attempt_number", attempt_number);
dict->SetInteger("net_error", net_error);
if (os_error) {
dict->SetInteger("os_error", os_error);
#if defined(OS_WIN)
// Map the error code to a human-readable string.
LPWSTR error_string = nullptr;
FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
nullptr, // Use the internal message table.
os_error,
0, // Use default language.
(LPWSTR)&error_string,
0, // Buffer size.
nullptr); // Arguments (unused).
dict->SetString("os_error_string", base::WideToUTF8(error_string));
LocalFree(error_string);
#elif defined(OS_POSIX) || defined(OS_FUCHSIA)
dict->SetString("os_error_string", gai_strerror(os_error));
#endif
}
return std::move(dict);
}
// Creates NetLog parameters when the DnsTask failed.
std::unique_ptr<base::Value> NetLogDnsTaskFailedCallback(
int net_error,
int dns_error,
NetLogParametersCallback results_callback,
NetLogCaptureMode capture_mode) {
std::unique_ptr<base::DictionaryValue> dict(new base::DictionaryValue());
dict->SetInteger("net_error", net_error);
if (dns_error)
dict->SetInteger("dns_error", dns_error);
if (results_callback)
dict->Set("resolve_results", results_callback.Run(capture_mode));
return std::move(dict);
}
// Creates NetLog parameters containing the information of the request. Use
// NetLogRequestInfoCallback if the request is specified via RequestInfo.
std::unique_ptr<base::Value> NetLogRequestCallback(
const HostPortPair& host,
NetLogCaptureMode /* capture_mode */) {
auto dict = std::make_unique<base::DictionaryValue>();
dict->SetString("host", host.ToString());
dict->SetInteger("address_family",
static_cast<int>(ADDRESS_FAMILY_UNSPECIFIED));
dict->SetBoolean("allow_cached_response", true);
dict->SetBoolean("is_speculative", false);
return std::move(dict);
}
// Creates NetLog parameters for the creation of a HostResolverManager::Job.
std::unique_ptr<base::Value> NetLogJobCreationCallback(
const NetLogSource& source,
const std::string* host,
NetLogCaptureMode /* capture_mode */) {
auto dict = std::make_unique<base::DictionaryValue>();
source.AddToEventParameters(dict.get());
dict->SetString("host", *host);
return std::move(dict);
}
// Creates NetLog parameters for HOST_RESOLVER_IMPL_JOB_ATTACH/DETACH events.
std::unique_ptr<base::Value> NetLogJobAttachCallback(
const NetLogSource& source,
RequestPriority priority,
NetLogCaptureMode /* capture_mode */) {
std::unique_ptr<base::DictionaryValue> dict(new base::DictionaryValue());
source.AddToEventParameters(dict.get());
dict->SetString("priority", RequestPriorityToString(priority));
return std::move(dict);
}
// Creates NetLog parameters for the DNS_CONFIG_CHANGED event.
std::unique_ptr<base::Value> NetLogDnsConfigCallback(
const DnsConfig* config,
NetLogCaptureMode /* capture_mode */) {
return config->ToValue();
}
std::unique_ptr<base::Value> NetLogIPv6AvailableCallback(
bool ipv6_available,
bool cached,
NetLogCaptureMode /* capture_mode */) {
std::unique_ptr<base::DictionaryValue> dict(new base::DictionaryValue());
dict->SetBoolean("ipv6_available", ipv6_available);
dict->SetBoolean("cached", cached);
return std::move(dict);
}
// The logging routines are defined here because some requests are resolved
// without a Request object.
// Logs when a request has just been started. Overloads for whether or not the
// request information is specified via a RequestInfo object.
void LogStartRequest(const NetLogWithSource& source_net_log,
const HostPortPair& host) {
source_net_log.BeginEvent(NetLogEventType::HOST_RESOLVER_IMPL_REQUEST,
base::BindRepeating(&NetLogRequestCallback, host));
}
// Logs when a request has just completed (before its callback is run).
void LogFinishRequest(const NetLogWithSource& source_net_log, int net_error) {
source_net_log.EndEventWithNetErrorCode(
NetLogEventType::HOST_RESOLVER_IMPL_REQUEST, net_error);
}
// Logs when a request has been cancelled.
void LogCancelRequest(const NetLogWithSource& source_net_log) {
source_net_log.AddEvent(NetLogEventType::CANCELLED);
source_net_log.EndEvent(NetLogEventType::HOST_RESOLVER_IMPL_REQUEST);
}
//-----------------------------------------------------------------------------
// Keeps track of the highest priority.
class PriorityTracker {
public:
explicit PriorityTracker(RequestPriority initial_priority)
: highest_priority_(initial_priority), total_count_(0) {
memset(counts_, 0, sizeof(counts_));
}
RequestPriority highest_priority() const { return highest_priority_; }
size_t total_count() const { return total_count_; }
void Add(RequestPriority req_priority) {
++total_count_;
++counts_[req_priority];
if (highest_priority_ < req_priority)
highest_priority_ = req_priority;
}
void Remove(RequestPriority req_priority) {
DCHECK_GT(total_count_, 0u);
DCHECK_GT(counts_[req_priority], 0u);
--total_count_;
--counts_[req_priority];
size_t i;
for (i = highest_priority_; i > MINIMUM_PRIORITY && !counts_[i]; --i) {
}
highest_priority_ = static_cast<RequestPriority>(i);
// In absence of requests, default to MINIMUM_PRIORITY.
if (total_count_ == 0)
DCHECK_EQ(MINIMUM_PRIORITY, highest_priority_);
}
private:
RequestPriority highest_priority_;
size_t total_count_;
size_t counts_[NUM_PRIORITIES];
};
// Is |dns_server| within the list of known DNS servers that also support
// DNS-over-HTTPS?
bool DnsServerSupportsDoh(const IPAddress& dns_server) {
static const base::NoDestructor<std::unordered_set<std::string>>
upgradable_servers(std::initializer_list<std::string>({
// Google Public DNS
"8.8.8.8",
"8.8.4.4",
"2001:4860:4860::8888",
"2001:4860:4860::8844",
// Cloudflare DNS
"1.1.1.1",
"1.0.0.1",
"2606:4700:4700::1111",
"2606:4700:4700::1001",
// Quad9 DNS
"9.9.9.9",
"149.112.112.112",
"2620:fe::fe",
"2620:fe::9",
}));
return upgradable_servers->find(dns_server.ToString()) !=
upgradable_servers->end();
}
} // namespace
//-----------------------------------------------------------------------------
bool ResolveLocalHostname(base::StringPiece host, AddressList* address_list) {
address_list->clear();
bool is_local6;
if (!IsLocalHostname(host, &is_local6))
return false;
address_list->push_back(IPEndPoint(IPAddress::IPv6Localhost(), 0));
if (!is_local6) {
address_list->push_back(IPEndPoint(IPAddress::IPv4Localhost(), 0));
}
return true;
}
const unsigned HostResolverManager::kMaximumDnsFailures = 16;
// Holds the callback and request parameters for an outstanding request.
//
// The RequestImpl is owned by the end user of host resolution. Deletion prior
// to the request having completed means the request was cancelled by the
// caller.
//
// Both the RequestImpl and its associated Job hold non-owning pointers to each
// other. Care must be taken to clear the corresponding pointer when
// cancellation is initiated by the Job (OnJobCancelled) vs by the end user
// (~RequestImpl).
class HostResolverManager::RequestImpl
: public HostResolver::ResolveHostRequest,
public base::LinkNode<HostResolverManager::RequestImpl> {
public:
RequestImpl(const NetLogWithSource& source_net_log,
const HostPortPair& request_host,
const base::Optional<ResolveHostParameters>& optional_parameters,
base::WeakPtr<HostResolverManager> resolver)
: source_net_log_(source_net_log),
request_host_(request_host),
parameters_(optional_parameters ? optional_parameters.value()
: ResolveHostParameters()),
host_resolver_flags_(
HostResolver::ParametersToHostResolverFlags(parameters_)),
priority_(parameters_.initial_priority),
job_(nullptr),
resolver_(resolver),
complete_(false) {}
~RequestImpl() override;
int Start(CompletionOnceCallback callback) override {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
DCHECK(callback);
// Start() may only be called once per request.
DCHECK(!job_);
DCHECK(!complete_);
DCHECK(!callback_);
// Parent HostResolver must still be alive to call Start().
DCHECK(resolver_);
int rv = resolver_->Resolve(this);
DCHECK(!complete_);
if (rv == ERR_IO_PENDING) {
DCHECK(job_);
callback_ = std::move(callback);
} else {
DCHECK(!job_);
complete_ = true;
}
resolver_ = nullptr;
return rv;
}
const base::Optional<AddressList>& GetAddressResults() const override {
DCHECK(complete_);
static const base::NoDestructor<base::Optional<AddressList>> nullopt_result;
return results_ ? results_.value().addresses() : *nullopt_result;
}
const base::Optional<std::vector<std::string>>& GetTextResults()
const override {
DCHECK(complete_);
static const base::NoDestructor<base::Optional<std::vector<std::string>>>
nullopt_result;
return results_ ? results_.value().text_records() : *nullopt_result;
}
const base::Optional<std::vector<HostPortPair>>& GetHostnameResults()
const override {
DCHECK(complete_);
static const base::NoDestructor<base::Optional<std::vector<HostPortPair>>>
nullopt_result;
return results_ ? results_.value().hostnames() : *nullopt_result;
}
const base::Optional<HostCache::EntryStaleness>& GetStaleInfo()
const override {
DCHECK(complete_);
return stale_info_;
}
void ChangeRequestPriority(RequestPriority priority) override;
void set_results(HostCache::Entry results) {
// Should only be called at most once and before request is marked
// completed.
DCHECK(!complete_);
DCHECK(!results_);
DCHECK(!parameters_.is_speculative);
results_ = std::move(results);
}
void set_stale_info(HostCache::EntryStaleness stale_info) {
// Should only be called at most once and before request is marked
// completed.
DCHECK(!complete_);
DCHECK(!stale_info_);
DCHECK(!parameters_.is_speculative);
stale_info_ = std::move(stale_info);
}
void AssignJob(Job* job) {
DCHECK(job);
DCHECK(!job_);
job_ = job;
}
// Unassigns the Job without calling completion callback.
void OnJobCancelled(Job* job) {
DCHECK_EQ(job_, job);
job_ = nullptr;
DCHECK(!complete_);
DCHECK(callback_);
callback_.Reset();
// No results should be set.
DCHECK(!results_);
}
// Cleans up Job assignment, marks request completed, and calls the completion
// callback.
void OnJobCompleted(Job* job, int error) {
DCHECK_EQ(job_, job);
job_ = nullptr;
DCHECK(!complete_);
complete_ = true;
DCHECK(callback_);
std::move(callback_).Run(error);
}
Job* job() const { return job_; }
// NetLog for the source, passed in HostResolver::Resolve.
const NetLogWithSource& source_net_log() { return source_net_log_; }
const HostPortPair& request_host() const { return request_host_; }
const ResolveHostParameters& parameters() const { return parameters_; }
HostResolverFlags host_resolver_flags() const { return host_resolver_flags_; }
RequestPriority priority() const { return priority_; }
void set_priority(RequestPriority priority) { priority_ = priority; }
bool complete() const { return complete_; }
base::TimeTicks request_time() const {
DCHECK(!request_time_.is_null());
return request_time_;
}
void set_request_time(base::TimeTicks request_time) {
DCHECK(request_time_.is_null());
DCHECK(!request_time.is_null());
request_time_ = request_time;
}
private:
const NetLogWithSource source_net_log_;
const HostPortPair request_host_;
const ResolveHostParameters parameters_;
const HostResolverFlags host_resolver_flags_;
RequestPriority priority_;
// The resolve job that this request is dependent on.
Job* job_;
base::WeakPtr<HostResolverManager> resolver_;
// The user's callback to invoke when the request completes.
CompletionOnceCallback callback_;
bool complete_;
base::Optional<HostCache::Entry> results_;
base::Optional<HostCache::EntryStaleness> stale_info_;
base::TimeTicks request_time_;
SEQUENCE_CHECKER(sequence_checker_);
DISALLOW_COPY_AND_ASSIGN(RequestImpl);
};
//------------------------------------------------------------------------------
// Calls HostResolverProc in TaskScheduler. Performs retries if necessary.
//
// In non-test code, the HostResolverProc is always SystemHostResolverProc,
// which calls a platform API that implements host resolution.
//
// Whenever we try to resolve the host, we post a delayed task to check if host
// resolution (OnLookupComplete) is completed or not. If the original attempt
// hasn't completed, then we start another attempt for host resolution. We take
// the results from the first attempt that finishes and ignore the results from
// all other attempts.
//
// TODO(szym): Move to separate source file for testing and mocking.
//
class HostResolverManager::ProcTask {
public:
typedef base::OnceCallback<void(int net_error, const AddressList& addr_list)>
Callback;
ProcTask(const Key& key,
const ProcTaskParams& params,
Callback callback,
scoped_refptr<base::TaskRunner> proc_task_runner,
const NetLogWithSource& job_net_log,
const base::TickClock* tick_clock)
: key_(key),
params_(params),
callback_(std::move(callback)),
network_task_runner_(base::ThreadTaskRunnerHandle::Get()),
proc_task_runner_(std::move(proc_task_runner)),
attempt_number_(0),
net_log_(job_net_log),
tick_clock_(tick_clock),
weak_ptr_factory_(this) {
// ProcTask only supports resolving addresses.
DCHECK(IsAddressType(key_.dns_query_type));
DCHECK(callback_);
if (!params_.resolver_proc.get())
params_.resolver_proc = HostResolverProc::GetDefault();
// If default is unset, use the system proc.
if (!params_.resolver_proc.get())
params_.resolver_proc = new SystemHostResolverProc();
}
// Cancels this ProcTask. Any outstanding resolve attempts running on worker
// thread will continue running, but they will post back to the network thread
// before checking their WeakPtrs to find that this task is cancelled.
~ProcTask() {
DCHECK(network_task_runner_->BelongsToCurrentThread());
// If this is cancellation, log the EndEvent (otherwise this was logged in
// OnLookupComplete()).
if (!was_completed())
net_log_.EndEvent(NetLogEventType::HOST_RESOLVER_IMPL_PROC_TASK);
}
void Start() {
DCHECK(network_task_runner_->BelongsToCurrentThread());
DCHECK(!was_completed());
net_log_.BeginEvent(NetLogEventType::HOST_RESOLVER_IMPL_PROC_TASK);
StartLookupAttempt();
}
bool was_completed() const {
DCHECK(network_task_runner_->BelongsToCurrentThread());
return callback_.is_null();
}
private:
using AttemptCompletionCallback = base::OnceCallback<
void(const AddressList& results, int error, const int os_error)>;
void StartLookupAttempt() {
DCHECK(network_task_runner_->BelongsToCurrentThread());
DCHECK(!was_completed());
base::TimeTicks start_time = tick_clock_->NowTicks();
++attempt_number_;
// Dispatch the lookup attempt to a worker thread.
AttemptCompletionCallback completion_callback = base::BindOnce(
&ProcTask::OnLookupAttemptComplete, weak_ptr_factory_.GetWeakPtr(),
start_time, attempt_number_, tick_clock_);
proc_task_runner_->PostTask(
FROM_HERE,
base::BindOnce(&ProcTask::DoLookup, key_, params_.resolver_proc,
network_task_runner_, std::move(completion_callback)));
net_log_.AddEvent(NetLogEventType::HOST_RESOLVER_IMPL_ATTEMPT_STARTED,
NetLog::IntCallback("attempt_number", attempt_number_));
// If the results aren't received within a given time, RetryIfNotComplete
// will start a new attempt if none of the outstanding attempts have
// completed yet.
// Use a WeakPtr to avoid keeping the ProcTask alive after completion or
// cancellation.
if (attempt_number_ <= params_.max_retry_attempts) {
network_task_runner_->PostDelayedTask(
FROM_HERE,
base::BindOnce(&ProcTask::StartLookupAttempt,
weak_ptr_factory_.GetWeakPtr()),
params_.unresponsive_delay *
std::pow(params_.retry_factor, attempt_number_ - 1));
}
}
// WARNING: This code runs in TaskScheduler with CONTINUE_ON_SHUTDOWN. The
// shutdown code cannot wait for it to finish, so this code must be very
// careful about using other objects (like MessageLoops, Singletons, etc).
// During shutdown these objects may no longer exist.
static void DoLookup(
Key key,
scoped_refptr<HostResolverProc> resolver_proc,
scoped_refptr<base::SingleThreadTaskRunner> network_task_runner,
AttemptCompletionCallback completion_callback) {
AddressList results;
int os_error = 0;
int error = resolver_proc->Resolve(
key.hostname,
HostResolver::DnsQueryTypeToAddressFamily(key.dns_query_type),
key.host_resolver_flags, &results, &os_error);
network_task_runner->PostTask(
FROM_HERE, base::BindOnce(std::move(completion_callback), results,
error, os_error));
}
// Callback for when DoLookup() completes (runs on task runner thread). Now
// that we're back in the network thread, checks that |proc_task| is still
// valid, and if so, passes back to the object.
static void OnLookupAttemptComplete(base::WeakPtr<ProcTask> proc_task,
const base::TimeTicks& start_time,
const uint32_t attempt_number,
const base::TickClock* tick_clock,
const AddressList& results,
int error,
const int os_error) {
TRACE_EVENT0(NetTracingCategory(), "ProcTask::OnLookupComplete");
// If results are empty, we should return an error.
bool empty_list_on_ok = (error == OK && results.empty());
if (empty_list_on_ok)
error = ERR_NAME_NOT_RESOLVED;
// Ideally the following code would be part of host_resolver_proc.cc,
// however it isn't safe to call NetworkChangeNotifier from worker threads.
// So do it here on the IO thread instead.
if (error != OK && NetworkChangeNotifier::IsOffline())
error = ERR_INTERNET_DISCONNECTED;
if (!proc_task)
return;
proc_task->OnLookupComplete(results, start_time, attempt_number, error,
os_error);
}
void OnLookupComplete(const AddressList& results,
const base::TimeTicks& start_time,
const uint32_t attempt_number,
int error,
const int os_error) {
DCHECK(network_task_runner_->BelongsToCurrentThread());
DCHECK(!was_completed());
// Invalidate WeakPtrs to cancel handling of all outstanding lookup attempts
// and retries.
weak_ptr_factory_.InvalidateWeakPtrs();
NetLogParametersCallback net_log_callback;
NetLogParametersCallback attempt_net_log_callback;
if (error != OK) {
net_log_callback = base::BindRepeating(&NetLogProcTaskFailedCallback, 0,
error, os_error);
attempt_net_log_callback = base::BindRepeating(
&NetLogProcTaskFailedCallback, attempt_number, error, os_error);
} else {
net_log_callback = results.CreateNetLogCallback();
attempt_net_log_callback =
NetLog::IntCallback("attempt_number", attempt_number);
}
net_log_.EndEvent(NetLogEventType::HOST_RESOLVER_IMPL_PROC_TASK,
net_log_callback);
net_log_.AddEvent(NetLogEventType::HOST_RESOLVER_IMPL_ATTEMPT_FINISHED,
attempt_net_log_callback);
std::move(callback_).Run(error, results);
}
Key key_;
// Holds an owning reference to the HostResolverProc that we are going to use.
// This may not be the current resolver procedure by the time we call
// ResolveAddrInfo, but that's OK... we'll use it anyways, and the owning
// reference ensures that it remains valid until we are done.
ProcTaskParams params_;
// The listener to the results of this ProcTask.
Callback callback_;
// Used to post events onto the network thread.
scoped_refptr<base::SingleThreadTaskRunner> network_task_runner_;
// Used to post blocking HostResolverProc tasks.
scoped_refptr<base::TaskRunner> proc_task_runner_;
// Keeps track of the number of attempts we have made so far to resolve the
// host. Whenever we start an attempt to resolve the host, we increase this
// number.
uint32_t attempt_number_;
NetLogWithSource net_log_;
const base::TickClock* tick_clock_;
// Used to loop back from the blocking lookup attempt tasks as well as from
// delayed retry tasks. Invalidate WeakPtrs on completion and cancellation to
// cancel handling of such posted tasks.
base::WeakPtrFactory<ProcTask> weak_ptr_factory_;
DISALLOW_COPY_AND_ASSIGN(ProcTask);
};
//-----------------------------------------------------------------------------
// Resolves the hostname using DnsTransaction, which is a full implementation of
// a DNS stub resolver. One DnsTransaction is created for each resolution
// needed, which for AF_UNSPEC resolutions includes both A and AAAA. The
// transactions are scheduled separately and started separately.
//
// TODO(szym): This could be moved to separate source file as well.
class HostResolverManager::DnsTask : public base::SupportsWeakPtr<DnsTask> {
public:
class Delegate {
public:
virtual void OnDnsTaskComplete(base::TimeTicks start_time,
const HostCache::Entry& results,
bool secure) = 0;
// Called when the first of two jobs succeeds. If the first completed
// transaction fails, this is not called. Also not called when the DnsTask
// only needs to run one transaction.
virtual void OnFirstDnsTransactionComplete() = 0;
virtual URLRequestContext* url_request_context() = 0;
virtual RequestPriority priority() const = 0;
protected:
Delegate() = default;
virtual ~Delegate() = default;
};
DnsTask(DnsClient* client,
const Key& key,
bool allow_fallback_resolution,
Delegate* delegate,
const NetLogWithSource& job_net_log,
const base::TickClock* tick_clock)
: client_(client),
key_(key),
allow_fallback_resolution_(allow_fallback_resolution),
delegate_(delegate),
net_log_(job_net_log),
num_completed_transactions_(0),
tick_clock_(tick_clock),
task_start_time_(tick_clock_->NowTicks()) {
DCHECK(client);
DCHECK(delegate_);
}
bool allow_fallback_resolution() const { return allow_fallback_resolution_; }
bool needs_two_transactions() const {
return key_.dns_query_type == DnsQueryType::UNSPECIFIED;
}
bool needs_another_transaction() const {
return needs_two_transactions() && !transaction2_;
}
void StartFirstTransaction() {
DCHECK_EQ(0u, num_completed_transactions_);
DCHECK(!transaction1_);
net_log_.BeginEvent(NetLogEventType::HOST_RESOLVER_IMPL_DNS_TASK);
if (key_.dns_query_type == DnsQueryType::UNSPECIFIED) {
transaction1_ = CreateTransaction(DnsQueryType::A);
} else {
transaction1_ = CreateTransaction(key_.dns_query_type);
}
transaction1_->Start();
}
void StartSecondTransaction() {
DCHECK(needs_another_transaction());
transaction2_ = CreateTransaction(DnsQueryType::AAAA);
transaction2_->Start();
}
private:
static const HostCache::Entry& GetMalformedResponseResult() {
static const base::NoDestructor<HostCache::Entry> kMalformedResponseResult(
ERR_DNS_MALFORMED_RESPONSE, HostCache::Entry::SOURCE_DNS);
return *kMalformedResponseResult;
}
std::unique_ptr<DnsTransaction> CreateTransaction(
DnsQueryType dns_query_type) {
DCHECK_NE(DnsQueryType::UNSPECIFIED, dns_query_type);
SecureDnsMode secure_dns_mode = SecureDnsMode::AUTOMATIC;
// Downgrade to OFF mode if the query name for this attempt matches one of
// the DoH server names. This is needed to prevent infinite recursion.
DCHECK(client_->GetConfig());
for (auto& doh_server : client_->GetConfig()->dns_over_https_servers) {
if (key_.hostname.compare(GURL(GetURLFromTemplateWithoutParameters(
doh_server.server_template))
.host()) == 0) {
secure_dns_mode = SecureDnsMode::OFF;
}
}
std::unique_ptr<DnsTransaction> trans =
client_->GetTransactionFactory()->CreateTransaction(
key_.hostname, DnsQueryTypeToQtype(dns_query_type),
base::BindOnce(&DnsTask::OnTransactionComplete,
base::Unretained(this), tick_clock_->NowTicks(),
dns_query_type),
net_log_, secure_dns_mode);
trans->SetRequestContext(delegate_->url_request_context());
trans->SetRequestPriority(delegate_->priority());
return trans;
}
void OnTransactionComplete(const base::TimeTicks& start_time,
DnsQueryType dns_query_type,
DnsTransaction* transaction,
int net_error,
const DnsResponse* response,
bool secure) {
DCHECK(transaction);
if (net_error != OK && !(net_error == ERR_NAME_NOT_RESOLVED && response &&
response->IsValid())) {
OnFailure(net_error, DnsResponse::DNS_PARSE_OK, base::nullopt, secure);
return;
}
DnsResponse::Result parse_result = DnsResponse::DNS_PARSE_RESULT_MAX;
HostCache::Entry results(ERR_FAILED, HostCache::Entry::SOURCE_UNKNOWN);
switch (dns_query_type) {
case DnsQueryType::UNSPECIFIED:
// Should create two separate transactions with specified type.
NOTREACHED();
break;
case DnsQueryType::A:
case DnsQueryType::AAAA:
parse_result = ParseAddressDnsResponse(response, &results);
break;
case DnsQueryType::TXT:
parse_result = ParseTxtDnsResponse(response, &results);
break;
case DnsQueryType::PTR:
parse_result = ParsePointerDnsResponse(response, &results);
break;
case DnsQueryType::SRV:
parse_result = ParseServiceDnsResponse(response, &results);
break;
}
DCHECK_LT(parse_result, DnsResponse::DNS_PARSE_RESULT_MAX);
if (results.error() != OK && results.error() != ERR_NAME_NOT_RESOLVED) {
OnFailure(results.error(), parse_result, results.GetOptionalTtl(),
secure);
return;
}
// Merge results with saved results from previous transactions.
DCHECK_EQ(saved_results_.has_value(), saved_secure_.has_value());
if (saved_results_) {
DCHECK(needs_two_transactions());
DCHECK_GE(1u, num_completed_transactions_);
switch (dns_query_type) {
case DnsQueryType::A:
// A results in |results| go after other results in |saved_results_|,
// so merge |saved_results_| to the front.
results = HostCache::Entry::MergeEntries(
std::move(saved_results_).value(), std::move(results));
break;
case DnsQueryType::AAAA:
// AAAA results in |results| go before other results in
// |saved_results_|, so merge |saved_results_| to the back.
results = HostCache::Entry::MergeEntries(
std::move(results), std::move(saved_results_).value());
break;
default:
// Only expect address query types with multiple transactions.
NOTREACHED();
}
// If the earlier result was retrieved insecurely, the merged result
// should be stored accordingly.
if (!saved_secure_.value())
secure = false;
}
// If not all transactions are complete, the task cannot yet be completed
// and the results so far must be saved to merge with additional results.
++num_completed_transactions_;
if (needs_two_transactions() && num_completed_transactions_ == 1) {
saved_results_ = std::move(results);
saved_secure_ = secure;
// No need to repeat the suffix search.
key_.hostname = transaction->GetHostname();
delegate_->OnFirstDnsTransactionComplete();
return;
}
// If there are multiple addresses, and at least one is IPv6, need to sort
// them. Note that IPv6 addresses are always put before IPv4 ones, so it's
// sufficient to just check the family of the first address.
if (results.addresses() && results.addresses().value().size() > 1 &&
results.addresses().value()[0].GetFamily() == ADDRESS_FAMILY_IPV6) {
// Sort addresses if needed. Sort could complete synchronously.
client_->GetAddressSorter()->Sort(
results.addresses().value(),
base::BindOnce(&DnsTask::OnSortComplete, AsWeakPtr(),
tick_clock_->NowTicks(), std::move(results), secure));
return;
}
OnSuccess(results, secure);
}
DnsResponse::Result ParseAddressDnsResponse(const DnsResponse* response,
HostCache::Entry* out_results) {
AddressList addresses;
base::TimeDelta ttl;
DnsResponse::Result parse_result =
response->ParseToAddressList(&addresses, &ttl);
if (parse_result != DnsResponse::DNS_PARSE_OK) {
*out_results = GetMalformedResponseResult();
} else if (addresses.empty()) {
*out_results = HostCache::Entry(ERR_NAME_NOT_RESOLVED, AddressList(),
HostCache::Entry::SOURCE_DNS, ttl);
} else {
*out_results = HostCache::Entry(OK, std::move(addresses),
HostCache::Entry::SOURCE_DNS, ttl);
}
return parse_result;
}
DnsResponse::Result ParseTxtDnsResponse(const DnsResponse* response,
HostCache::Entry* out_results) {
std::vector<std::unique_ptr<const RecordParsed>> records;
base::Optional<base::TimeDelta> response_ttl;
DnsResponse::Result parse_result = ParseAndFilterResponseRecords(
response, dns_protocol::kTypeTXT, &records, &response_ttl);
if (parse_result != DnsResponse::DNS_PARSE_OK) {
*out_results = GetMalformedResponseResult();
return parse_result;
}
std::vector<std::string> text_records;
for (const auto& record : records) {
const TxtRecordRdata* rdata = record->rdata<net::TxtRecordRdata>();
text_records.insert(text_records.end(), rdata->texts().begin(),
rdata->texts().end());
}
*out_results = HostCache::Entry(
text_records.empty() ? ERR_NAME_NOT_RESOLVED : OK,
std::move(text_records), HostCache::Entry::SOURCE_DNS, response_ttl);
return DnsResponse::DNS_PARSE_OK;
}
DnsResponse::Result ParsePointerDnsResponse(const DnsResponse* response,
HostCache::Entry* out_results) {
std::vector<std::unique_ptr<const RecordParsed>> records;
base::Optional<base::TimeDelta> response_ttl;
DnsResponse::Result parse_result = ParseAndFilterResponseRecords(
response, dns_protocol::kTypePTR, &records, &response_ttl);
if (parse_result != DnsResponse::DNS_PARSE_OK) {
*out_results = GetMalformedResponseResult();
return parse_result;
}
std::vector<HostPortPair> pointers;
for (const auto& record : records) {
const PtrRecordRdata* rdata = record->rdata<net::PtrRecordRdata>();
std::string pointer = rdata->ptrdomain();
// Skip pointers to the root domain.
if (!pointer.empty())
pointers.emplace_back(std::move(pointer), 0);
}
*out_results = HostCache::Entry(
pointers.empty() ? ERR_NAME_NOT_RESOLVED : OK, std::move(pointers),
HostCache::Entry::SOURCE_DNS, response_ttl);
return DnsResponse::DNS_PARSE_OK;
}
DnsResponse::Result ParseServiceDnsResponse(const DnsResponse* response,
HostCache::Entry* out_results) {
std::vector<std::unique_ptr<const RecordParsed>> records;
base::Optional<base::TimeDelta> response_ttl;
DnsResponse::Result parse_result = ParseAndFilterResponseRecords(
response, dns_protocol::kTypeSRV, &records, &response_ttl);
if (parse_result != DnsResponse::DNS_PARSE_OK) {
*out_results = GetMalformedResponseResult();
return parse_result;
}
std::vector<const SrvRecordRdata*> fitered_rdatas;
for (const auto& record : records) {
const SrvRecordRdata* rdata = record->rdata<net::SrvRecordRdata>();
// Skip pointers to the root domain.
if (!rdata->target().empty())
fitered_rdatas.push_back(rdata);
}
std::vector<HostPortPair> ordered_service_targets =
SortServiceTargets(fitered_rdatas);
*out_results = HostCache::Entry(
ordered_service_targets.empty() ? ERR_NAME_NOT_RESOLVED : OK,
std::move(ordered_service_targets), HostCache::Entry::SOURCE_DNS,
response_ttl);
return DnsResponse::DNS_PARSE_OK;
}
// Sort service targets per RFC2782. In summary, sort first by |priority|,
// lowest first. For targets with the same priority, secondary sort randomly
// using |weight| with higher weighted objects more likely to go first.
std::vector<HostPortPair> SortServiceTargets(
const std::vector<const SrvRecordRdata*>& rdatas) {
std::map<uint16_t, std::unordered_set<const SrvRecordRdata*>>
ordered_by_priority;
for (const SrvRecordRdata* rdata : rdatas)
ordered_by_priority[rdata->priority()].insert(rdata);
std::vector<HostPortPair> sorted_targets;
for (auto& priority : ordered_by_priority) {
// With (num results) <= UINT16_MAX (and in practice, much less) and
// (weight per result) <= UINT16_MAX, then it should be the case that
// (total weight) <= UINT32_MAX, but use CheckedNumeric for extra safety.
auto total_weight = base::MakeCheckedNum<uint32_t>(0);
for (const SrvRecordRdata* rdata : priority.second)
total_weight += rdata->weight();
// Add 1 to total weight because, to deal with 0-weight targets, we want
// our random selection to be inclusive [0, total].
total_weight++;
// Order by weighted random. Make such random selections, removing from
// |priority.second| until |priority.second| only contains 1 rdata.
while (priority.second.size() >= 2) {
uint32_t random_selection =
base::RandGenerator(total_weight.ValueOrDie());
const SrvRecordRdata* selected_rdata = nullptr;
for (const SrvRecordRdata* rdata : priority.second) {
// >= to always select the first target on |random_selection| == 0,
// even if its weight is 0.
if (rdata->weight() >= random_selection) {
selected_rdata = rdata;
break;
}
random_selection -= rdata->weight();
}
DCHECK(selected_rdata);
sorted_targets.emplace_back(selected_rdata->target(),
selected_rdata->port());
total_weight -= selected_rdata->weight();
size_t removed = priority.second.erase(selected_rdata);
DCHECK_EQ(1u, removed);
}
DCHECK_EQ(1u, priority.second.size());
DCHECK_EQ((total_weight - 1).ValueOrDie(),
(*priority.second.begin())->weight());
const SrvRecordRdata* rdata = *priority.second.begin();
sorted_targets.emplace_back(rdata->target(), rdata->port());
}
return sorted_targets;
}
DnsResponse::Result ParseAndFilterResponseRecords(
const DnsResponse* response,
uint16_t filter_dns_type,
std::vector<std::unique_ptr<const RecordParsed>>* out_records,
base::Optional<base::TimeDelta>* out_response_ttl) {
out_records->clear();
out_response_ttl->reset();
DnsRecordParser parser = response->Parser();
// Expected to be validated by DnsTransaction.
DCHECK_EQ(filter_dns_type, response->qtype());
for (unsigned i = 0; i < response->answer_count(); ++i) {
std::unique_ptr<const RecordParsed> record =
RecordParsed::CreateFrom(&parser, base::Time::Now());
if (!record)
return DnsResponse::DNS_MALFORMED_RESPONSE;
if (!base::EqualsCaseInsensitiveASCII(record->name(),
response->GetDottedName())) {
return DnsResponse::DNS_NAME_MISMATCH;
}
// Ignore any records that are not class Internet and type
// |filter_dns_type|.
if (record->klass() == dns_protocol::kClassIN &&
record->type() == filter_dns_type) {
base::TimeDelta ttl = base::TimeDelta::FromSeconds(record->ttl());
*out_response_ttl =
std::min(out_response_ttl->value_or(base::TimeDelta::Max()), ttl);
out_records->push_back(std::move(record));
}
}
return DnsResponse::DNS_PARSE_OK;
}
void OnSortComplete(base::TimeTicks sort_start_time,
HostCache::Entry results,
bool secure,
bool success,
const AddressList& addr_list) {
results.set_addresses(addr_list);
if (!success) {
OnFailure(ERR_DNS_SORT_ERROR, DnsResponse::DNS_PARSE_OK,
results.GetOptionalTtl(), secure);
return;
}
// AddressSorter prunes unusable destinations.
if (addr_list.empty() &&
results.text_records().value_or(std::vector<std::string>()).empty() &&
results.hostnames().value_or(std::vector<HostPortPair>()).empty()) {
LOG(WARNING) << "Address list empty after RFC3484 sort";
OnFailure(ERR_NAME_NOT_RESOLVED, DnsResponse::DNS_PARSE_OK,
results.GetOptionalTtl(), secure);
return;
}
OnSuccess(results, secure);
}
void OnFailure(int net_error,
DnsResponse::Result parse_result,
base::Optional<base::TimeDelta> ttl,
bool secure) {
DCHECK_NE(OK, net_error);
HostCache::Entry results(net_error, HostCache::Entry::SOURCE_UNKNOWN);
net_log_.EndEvent(NetLogEventType::HOST_RESOLVER_IMPL_DNS_TASK,
base::Bind(&NetLogDnsTaskFailedCallback, results.error(),
parse_result, results.CreateNetLogCallback()));
// If we have a TTL from a previously completed transaction, use it.
DCHECK_EQ(saved_results_.has_value(), saved_secure_.has_value());
base::TimeDelta previous_transaction_ttl;
if (saved_results_ && saved_results_.value().has_ttl() &&
saved_results_.value().ttl() <
base::TimeDelta::FromSeconds(
std::numeric_limits<uint32_t>::max())) {
previous_transaction_ttl = saved_results_.value().ttl();
if (ttl)
results.set_ttl(std::min(ttl.value(), previous_transaction_ttl));
else
results.set_ttl(previous_transaction_ttl);
} else if (ttl) {
results.set_ttl(ttl.value());
}
// If the earlier result was retrieved insecurely, any entry stored in the
// cache for this transaction should be stored with an insecure key.
if (saved_secure_ && !saved_secure_.value())
secure = false;
delegate_->OnDnsTaskComplete(task_start_time_, results, secure);
}
void OnSuccess(const HostCache::Entry& results, bool secure) {
net_log_.EndEvent(NetLogEventType::HOST_RESOLVER_IMPL_DNS_TASK,
results.CreateNetLogCallback());
delegate_->OnDnsTaskComplete(task_start_time_, results, secure);
}
DnsClient* client_;
Key key_;
// Whether resolution may fallback to other task types (e.g. ProcTask) on
// failure of this task.
bool allow_fallback_resolution_;
// The listener to the results of this DnsTask.
Delegate* delegate_;
const NetLogWithSource net_log_;
std::unique_ptr<DnsTransaction> transaction1_;
std::unique_ptr<DnsTransaction> transaction2_;
unsigned num_completed_transactions_;
// Result from previously completed transactions. Only set if a transaction
// has completed while others are still in progress.
base::Optional<HostCache::Entry> saved_results_;
// Whether the result from the previously completed transaction was retrieved
// securely. Only set if a transaction has completed while others are still
// in progress.
base::Optional<bool> saved_secure_;
const base::TickClock* tick_clock_;
base::TimeTicks task_start_time_;
DISALLOW_COPY_AND_ASSIGN(DnsTask);
};
//-----------------------------------------------------------------------------
// Aggregates all Requests for the same Key. Dispatched via PriorityDispatch.
class HostResolverManager::Job : public PrioritizedDispatcher::Job,
public HostResolverManager::DnsTask::Delegate {
public:
// Creates new job for |key| where |request_net_log| is bound to the
// request that spawned it.
Job(const base::WeakPtr<HostResolverManager>& resolver,
const Key& key,
RequestPriority priority,
scoped_refptr<base::TaskRunner> proc_task_runner,
const NetLogWithSource& source_net_log,
const base::TickClock* tick_clock)
: resolver_(resolver),
key_(key),
priority_tracker_(priority),
proc_task_runner_(std::move(proc_task_runner)),
had_non_speculative_request_(false),
num_occupied_job_slots_(0),
dns_task_error_(OK),
tick_clock_(tick_clock),
net_log_(
NetLogWithSource::Make(source_net_log.net_log(),
NetLogSourceType::HOST_RESOLVER_IMPL_JOB)),
weak_ptr_factory_(this) {
source_net_log.AddEvent(NetLogEventType::HOST_RESOLVER_IMPL_CREATE_JOB);
net_log_.BeginEvent(NetLogEventType::HOST_RESOLVER_IMPL_JOB,
base::Bind(&NetLogJobCreationCallback,
source_net_log.source(), &key_.hostname));
}
~Job() override {
if (is_running()) {
// |resolver_| was destroyed with this Job still in flight.
// Clean-up, record in the log, but don't run any callbacks.
proc_task_ = nullptr;
// Clean up now for nice NetLog.
KillDnsTask();
net_log_.EndEventWithNetErrorCode(NetLogEventType::HOST_RESOLVER_IMPL_JOB,
ERR_ABORTED);
} else if (is_queued()) {
// |resolver_| was destroyed without running this Job.
// TODO(szym): is there any benefit in having this distinction?
net_log_.AddEvent(NetLogEventType::CANCELLED);
net_log_.EndEvent(NetLogEventType::HOST_RESOLVER_IMPL_JOB);
}
// else CompleteRequests logged EndEvent.
while (!requests_.empty()) {
// Log any remaining Requests as cancelled.
RequestImpl* req = requests_.head()->value();
req->RemoveFromList();
DCHECK_EQ(this, req->job());
LogCancelRequest(req->source_net_log());
req->OnJobCancelled(this);
}
}
// Add this job to the dispatcher. If "at_head" is true, adds at the front
// of the queue.
void Schedule(bool at_head) {
DCHECK(!is_queued());
PrioritizedDispatcher::Handle handle;
if (!at_head) {
handle = resolver_->dispatcher_->Add(this, priority());
} else {
handle = resolver_->dispatcher_->AddAtHead(this, priority());
}
// The dispatcher could have started |this| in the above call to Add, which
// could have called Schedule again. In that case |handle| will be null,
// but |handle_| may have been set by the other nested call to Schedule.
if (!handle.is_null()) {
DCHECK(handle_.is_null());
handle_ = handle;
}
}
void AddRequest(RequestImpl* request) {
DCHECK_EQ(key_.hostname, request->request_host().host());
request->AssignJob(this);
priority_tracker_.Add(request->priority());
request->source_net_log().AddEvent(
NetLogEventType::HOST_RESOLVER_IMPL_JOB_ATTACH,
net_log_.source().ToEventParametersCallback());
net_log_.AddEvent(
NetLogEventType::HOST_RESOLVER_IMPL_JOB_REQUEST_ATTACH,
base::Bind(&NetLogJobAttachCallback, request->source_net_log().source(),
priority()));
if (!request->parameters().is_speculative)
had_non_speculative_request_ = true;
requests_.Append(request);
UpdatePriority();
}
void ChangeRequestPriority(RequestImpl* req, RequestPriority priority) {
DCHECK_EQ(key_.hostname, req->request_host().host());
priority_tracker_.Remove(req->priority());
req->set_priority(priority);
priority_tracker_.Add(req->priority());
UpdatePriority();
}
// Detach cancelled request. If it was the last active Request, also finishes
// this Job.
void CancelRequest(RequestImpl* request) {
DCHECK_EQ(key_.hostname, request->request_host().host());
DCHECK(!requests_.empty());
LogCancelRequest(request->source_net_log());
priority_tracker_.Remove(request->priority());
net_log_.AddEvent(
NetLogEventType::HOST_RESOLVER_IMPL_JOB_REQUEST_DETACH,
base::Bind(&NetLogJobAttachCallback, request->source_net_log().source(),
priority()));
if (num_active_requests() > 0) {
UpdatePriority();
request->RemoveFromList();
} else {
// If we were called from a Request's callback within CompleteRequests,
// that Request could not have been cancelled, so num_active_requests()
// could not be 0. Therefore, we are not in CompleteRequests().
CompleteRequestsWithError(ERR_FAILED /* cancelled */);
}
}
// Called from AbortAllInProgressJobs. Completes all requests and destroys
// the job. This currently assumes the abort is due to a network change.
// TODO This should not delete |this|.
void Abort() {
DCHECK(is_running());
CompleteRequestsWithError(ERR_NETWORK_CHANGED);
}
// Gets a closure that will abort a DnsTask (see AbortDnsTask()) iff |this| is
// still valid. Useful if aborting a list of Jobs as some may be cancelled
// while aborting others.
base::OnceClosure GetAbortDnsTaskClosure(int error, bool fallback_only) {
return base::BindOnce(&Job::AbortDnsTask, weak_ptr_factory_.GetWeakPtr(),
error, fallback_only);
}
// If DnsTask present, abort it. Depending on task settings, either fall back
// to ProcTask or abort the job entirely. Warning, aborting a job may cause
// other jobs to be aborted, thus |jobs_| may be unpredictably changed by
// calling this method.
//
// |error| is the net error that will be returned to requests if this method
// results in completely aborting the job.
void AbortDnsTask(int error, bool fallback_only) {
if (dns_task_) {
if (dns_task_->allow_fallback_resolution()) {
KillDnsTask();
dns_task_error_ = OK;
StartProcTask();
} else if (!fallback_only) {
CompleteRequestsWithError(error);
}
}
}
// Called by HostResolverManager when this job is evicted due to queue
// overflow. Completes all requests and destroys the job.
void OnEvicted(bool complete_asynchronously) {
DCHECK(!is_running());
DCHECK(is_queued());
handle_.Reset();
net_log_.AddEvent(NetLogEventType::HOST_RESOLVER_IMPL_JOB_EVICTED);
// This signals to CompleteRequests that this job never ran.
if (complete_asynchronously) {
// Job must be saved in |resolver_| to be completed asynchronously.
// Otherwise the job will be destroyed with requests silently cancelled
// before completion runs.
DCHECK_EQ(1u, resolver_->jobs_.count(key_));
base::SequencedTaskRunnerHandle::Get()->PostTask(
FROM_HERE, base::BindOnce(&Job::CompleteRequestsWithError,
weak_ptr_factory_.GetWeakPtr(),
ERR_HOST_RESOLVER_QUEUE_TOO_LARGE));
} else {
// Should not complete synchronously with eviction if requests are
// attached to the job because those requests will invoke callbacks that
// could result in reentrancy.
DCHECK_EQ(0u, num_active_requests());
CompleteRequestsWithError(ERR_HOST_RESOLVER_QUEUE_TOO_LARGE);
}
}
// Attempts to serve the job from HOSTS. Returns true if succeeded and
// this Job was destroyed.
bool ServeFromHosts() {
DCHECK_GT(num_active_requests(), 0u);
base::Optional<HostCache::Entry> results = resolver_->ServeFromHosts(key());
if (results) {
// This will destroy the Job.
CompleteRequests(results.value(), base::TimeDelta(),
true /* allow_cache */, true /* secure */);
return true;
}
return false;
}
const Key& key() const { return key_; }
bool is_queued() const { return !handle_.is_null(); }
bool is_running() const {
return is_dns_running() || is_mdns_running() || is_proc_running();
}
private:
void KillDnsTask() {
if (dns_task_) {
ReduceToOneJobSlot();
dns_task_.reset();
}
}
// Reduce the number of job slots occupied and queued in the dispatcher
// to one. If the second Job slot is queued in the dispatcher, cancels the
// queued job. Otherwise, the second Job has been started by the
// PrioritizedDispatcher, so signals it is complete.
void ReduceToOneJobSlot() {
DCHECK_GE(num_occupied_job_slots_, 1u);
if (is_queued()) {
resolver_->dispatcher_->Cancel(handle_);
handle_.Reset();
} else if (num_occupied_job_slots_ > 1) {
resolver_->dispatcher_->OnJobFinished();
--num_occupied_job_slots_;
}
DCHECK_EQ(1u, num_occupied_job_slots_);
}
void UpdatePriority() {
if (is_queued())
handle_ = resolver_->dispatcher_->ChangePriority(handle_, priority());
}
// PriorityDispatch::Job:
void Start() override {
DCHECK_LE(num_occupied_job_slots_, 1u);
handle_.Reset();
++num_occupied_job_slots_;
if (num_occupied_job_slots_ == 2) {
StartSecondDnsTransaction();
return;
}
DCHECK(!is_running());
net_log_.AddEvent(NetLogEventType::HOST_RESOLVER_IMPL_JOB_STARTED);
start_time_ = tick_clock_->NowTicks();
switch (key_.host_resolver_source) {
case HostResolverSource::ANY:
// Force address queries with canonname to use ProcTask to counter poor
// CNAME support in DnsTask. See https://crbug.com/872665
//
// Otherwise, default to DnsTask (with allowed fallback to ProcTask for
// address queries). But if hostname appears to be an MDNS name (ends in
// *.local), go with ProcTask for address queries and MdnsTask for non-
// address queries.
if ((key_.host_resolver_flags & HOST_RESOLVER_CANONNAME) &&
IsAddressType(key_.dns_query_type)) {
StartProcTask();
} else if (!ResemblesMulticastDNSName(key_.hostname)) {
StartDnsTask(IsAddressType(
key_.dns_query_type) /* allow_fallback_resolution */);
} else if (IsAddressType(key_.dns_query_type)) {
StartProcTask();
} else {
StartMdnsTask();
}
break;
case HostResolverSource::SYSTEM:
StartProcTask();
break;
case HostResolverSource::DNS:
StartDnsTask(false /* allow_fallback_resolution */);
break;
case HostResolverSource::MULTICAST_DNS:
StartMdnsTask();
break;
case HostResolverSource::LOCAL_ONLY:
// If no external source allowed, a job should not be created or started
NOTREACHED();
break;
}
// Caution: Job::Start must not complete synchronously.
}
// TODO(szym): Since DnsTransaction does not consume threads, we can increase
// the limits on |dispatcher_|. But in order to keep the number of
// TaskScheduler threads low, we will need to use an "inner"
// PrioritizedDispatcher with tighter limits.
void StartProcTask() {
DCHECK(!is_running());
DCHECK(IsAddressType(key_.dns_query_type));
proc_task_ = std::make_unique<ProcTask>(
key_, resolver_->proc_params_,
base::BindOnce(&Job::OnProcTaskComplete, base::Unretained(this),
tick_clock_->NowTicks()),
proc_task_runner_, net_log_, tick_clock_);
// Start() could be called from within Resolve(), hence it must NOT directly
// call OnProcTaskComplete, for example, on synchronous failure.
proc_task_->Start();
}
// Called by ProcTask when it completes.
void OnProcTaskComplete(base::TimeTicks start_time,
int net_error,
const AddressList& addr_list) {
DCHECK(is_proc_running());
if (dns_task_error_ != OK) {
// This ProcTask was a fallback resolution after a failed DnsTask.
if (net_error == OK) {
resolver_->OnFallbackResolve(dns_task_error_);
}
}
if (ContainsIcannNameCollisionIp(addr_list))
net_error = ERR_ICANN_NAME_COLLISION;
base::TimeDelta ttl =
base::TimeDelta::FromSeconds(kNegativeCacheEntryTTLSeconds);
if (net_error == OK)
ttl = base::TimeDelta::FromSeconds(kCacheEntryTTLSeconds);
// Source unknown because the system resolver could have gotten it from a
// hosts file, its own cache, a DNS lookup or somewhere else.
// Don't store the |ttl| in cache since it's not obtained from the server.
CompleteRequests(
HostCache::Entry(net_error,
net_error == OK
? AddressList::CopyWithPort(addr_list, 0)
: AddressList(),
HostCache::Entry::SOURCE_UNKNOWN),
ttl, true /* allow_cache */, false /* secure */);
}
void StartDnsTask(bool allow_fallback_resolution) {
if ((!resolver_->HaveDnsConfig() || resolver_->use_proctask_by_default_) &&
allow_fallback_resolution) {
// DnsClient or config is not available, but we're allowed to switch to
// ProcTask instead.
StartProcTask();
return;
}
// Need to create the task even if we're going to post a failure instead of
// running it, as a "started" job needs a task to be properly cleaned up.
dns_task_.reset(new DnsTask(resolver_->dns_client_.get(), key_,
allow_fallback_resolution, this, net_log_,
tick_clock_));
if (resolver_->HaveDnsConfig()) {
dns_task_->StartFirstTransaction();
// Schedule a second transaction, if needed.
if (dns_task_->needs_two_transactions())
Schedule(true);
} else {
// Cannot start a DNS task when DnsClient or config is not available.
// Since we cannot complete synchronously from here, post a failure.
base::SequencedTaskRunnerHandle::Get()->PostTask(
FROM_HERE,
base::BindOnce(
&Job::OnDnsTaskFailure, weak_ptr_factory_.GetWeakPtr(),
dns_task_->AsWeakPtr(), base::TimeDelta(),
HostCache::Entry(ERR_FAILED, HostCache::Entry::SOURCE_UNKNOWN),
false /* secure */));
}
}
void StartSecondDnsTransaction() {
DCHECK(dns_task_->needs_two_transactions());
dns_task_->StartSecondTransaction();
}
// Called if DnsTask fails. It is posted from StartDnsTask, so Job may be
// deleted before this callback. In this case dns_task is deleted as well,
// so we use it as indicator whether Job is still valid.
void OnDnsTaskFailure(const base::WeakPtr<DnsTask>& dns_task,
base::TimeDelta duration,
const HostCache::Entry& failure_results,
bool secure) {
DCHECK_NE(OK, failure_results.error());
UMA_HISTOGRAM_LONG_TIMES_100("Net.DNS.DnsTask.FailureTime", duration);
if (!dns_task)
return;
if (duration < base::TimeDelta::FromMilliseconds(10)) {
base::UmaHistogramSparse("Net.DNS.DnsTask.ErrorBeforeFallback.Fast",
std::abs(failure_results.error()));
} else {
base::UmaHistogramSparse("Net.DNS.DnsTask.ErrorBeforeFallback.Slow",
std::abs(failure_results.error()));
}
dns_task_error_ = failure_results.error();
// TODO(szym): Run ServeFromHosts now if nsswitch.conf says so.
// http://crbug.com/117655
// TODO(szym): Some net errors indicate lack of connectivity. Starting
// ProcTask in that case is a waste of time.
if (resolver_->allow_fallback_to_proctask_ &&
dns_task->allow_fallback_resolution()) {
KillDnsTask();
StartProcTask();
} else {
base::TimeDelta ttl = failure_results.has_ttl()
? failure_results.ttl()
: base::TimeDelta::FromSeconds(0);
CompleteRequests(failure_results, ttl, true /* allow_cache */, secure);
}
}
// HostResolverManager::DnsTask::Delegate implementation:
void OnDnsTaskComplete(base::TimeTicks start_time,
const HostCache::Entry& results,
bool secure) override {
DCHECK(is_dns_running());
base::TimeDelta duration = tick_clock_->NowTicks() - start_time;
if (results.error() != OK) {
OnDnsTaskFailure(dns_task_->AsWeakPtr(), duration, results, secure);
return;
}
UMA_HISTOGRAM_LONG_TIMES_100("Net.DNS.DnsTask.SuccessTime", duration);
resolver_->OnDnsTaskResolve();
base::TimeDelta bounded_ttl = std::max(
results.ttl(), base::TimeDelta::FromSeconds(kMinimumTTLSeconds));
if (results.addresses() &&
ContainsIcannNameCollisionIp(results.addresses().value())) {
CompleteRequestsWithError(ERR_ICANN_NAME_COLLISION);
return;
}
CompleteRequests(results, bounded_ttl, true /* allow_cache */, secure);
}
void OnFirstDnsTransactionComplete() override {
DCHECK(dns_task_->needs_two_transactions());
DCHECK_EQ(dns_task_->needs_another_transaction(), is_queued());
// No longer need to occupy two dispatcher slots.
ReduceToOneJobSlot();
// We already have a job slot at the dispatcher, so if the second
// transaction hasn't started, reuse it now instead of waiting in the queue
// for the second slot.
if (dns_task_->needs_another_transaction())
dns_task_->StartSecondTransaction();
}
void StartMdnsTask() {
DCHECK(!is_running());
// No flags are supported for MDNS except
// HOST_RESOLVER_DEFAULT_FAMILY_SET_DUE_TO_NO_IPV6 (which is not actually an
// input flag).
DCHECK_EQ(0, key_.host_resolver_flags &
~HOST_RESOLVER_DEFAULT_FAMILY_SET_DUE_TO_NO_IPV6);
std::vector<DnsQueryType> query_types;
if (key_.dns_query_type == DnsQueryType::UNSPECIFIED) {
query_types.push_back(DnsQueryType::A);
query_types.push_back(DnsQueryType::AAAA);
} else {
query_types.push_back(key_.dns_query_type);
}
MDnsClient* client;
int rv = resolver_->GetOrCreateMdnsClient(&client);
mdns_task_ = std::make_unique<HostResolverMdnsTask>(client, key_.hostname,
query_types);
if (rv == OK) {
mdns_task_->Start(
base::BindOnce(&Job::OnMdnsTaskComplete, base::Unretained(this)));
} else {
// Could not create an mDNS client. Since we cannot complete synchronously
// from here, post a failure without starting the task.
base::SequencedTaskRunnerHandle::Get()->PostTask(
FROM_HERE, base::BindOnce(&Job::OnMdnsImmediateFailure,
weak_ptr_factory_.GetWeakPtr(), rv));
}
}
void OnMdnsTaskComplete() {
DCHECK(is_mdns_running());
// TODO(crbug.com/846423): Consider adding MDNS-specific logging.
HostCache::Entry results = mdns_task_->GetResults();
if (results.addresses() &&
ContainsIcannNameCollisionIp(results.addresses().value())) {
CompleteRequestsWithError(ERR_ICANN_NAME_COLLISION);
} else {
// MDNS uses a separate cache, so skip saving result to cache.
// TODO(crbug.com/926300): Consider merging caches.
CompleteRequestsWithoutCache(results);
}
}
void OnMdnsImmediateFailure(int rv) {
DCHECK(is_mdns_running());
DCHECK_NE(OK, rv);
CompleteRequestsWithError(rv);
}
URLRequestContext* url_request_context() override {
return resolver_->url_request_context_;
}
void RecordJobHistograms(int error) {
// Used in UMA_HISTOGRAM_ENUMERATION. Do not renumber entries or reuse
// deprecated values.
enum Category {
RESOLVE_SUCCESS = 0,
RESOLVE_FAIL = 1,
RESOLVE_SPECULATIVE_SUCCESS = 2,
RESOLVE_SPECULATIVE_FAIL = 3,
RESOLVE_ABORT = 4,
RESOLVE_SPECULATIVE_ABORT = 5,
RESOLVE_MAX, // Bounding value.
};
Category category = RESOLVE_MAX; // Illegal value for later DCHECK only.
base::TimeDelta duration = tick_clock_->NowTicks() - start_time_;
if (error == OK) {
if (had_non_speculative_request_) {
category = RESOLVE_SUCCESS;
UMA_HISTOGRAM_LONG_TIMES_100("Net.DNS.ResolveSuccessTime", duration);
switch (key_.dns_query_type) {
case DnsQueryType::A:
UMA_HISTOGRAM_LONG_TIMES_100("Net.DNS.ResolveSuccessTime.IPV4",
duration);
break;
case DnsQueryType::AAAA:
UMA_HISTOGRAM_LONG_TIMES_100("Net.DNS.ResolveSuccessTime.IPV6",
duration);
break;
case DnsQueryType::UNSPECIFIED:
UMA_HISTOGRAM_LONG_TIMES_100("Net.DNS.ResolveSuccessTime.UNSPEC",
duration);
break;
default:
// No histogram for other query types.
break;
}
} else {
category = RESOLVE_SPECULATIVE_SUCCESS;
}
} else if (error == ERR_NETWORK_CHANGED ||
error == ERR_HOST_RESOLVER_QUEUE_TOO_LARGE) {
category = had_non_speculative_request_ ? RESOLVE_ABORT
: RESOLVE_SPECULATIVE_ABORT;
} else {
if (had_non_speculative_request_) {
category = RESOLVE_FAIL;
UMA_HISTOGRAM_LONG_TIMES_100("Net.DNS.ResolveFailureTime", duration);
switch (key_.dns_query_type) {
case DnsQueryType::A:
UMA_HISTOGRAM_LONG_TIMES_100("Net.DNS.ResolveFailureTime.IPV4",
duration);
break;
case DnsQueryType::AAAA:
UMA_HISTOGRAM_LONG_TIMES_100("Net.DNS.ResolveFailureTime.IPV6",
duration);
break;
case DnsQueryType::UNSPECIFIED:
UMA_HISTOGRAM_LONG_TIMES_100("Net.DNS.ResolveFailureTime.UNSPEC",
duration);
break;
default:
// No histogram for other query types.
break;
}
} else {
category = RESOLVE_SPECULATIVE_FAIL;
}
}
DCHECK_LT(static_cast<int>(category),
static_cast<int>(RESOLVE_MAX)); // Be sure it was set.
UMA_HISTOGRAM_ENUMERATION("Net.DNS.ResolveCategory", category, RESOLVE_MAX);
if (category == RESOLVE_FAIL || category == RESOLVE_ABORT) {
if (duration < base::TimeDelta::FromMilliseconds(10))
base::UmaHistogramSparse("Net.DNS.ResolveError.Fast", std::abs(error));
else
base::UmaHistogramSparse("Net.DNS.ResolveError.Slow", std::abs(error));
}
}
// Performs Job's last rites. Completes all Requests. Deletes this.
//
// If not |allow_cache|, result will not be stored in the host cache, even if
// result would otherwise allow doing so. Update the key to reflect |secure|,
// which indicates whether or not the result was obtained securely.
void CompleteRequests(const HostCache::Entry& results,
base::TimeDelta ttl,
bool allow_cache,
bool secure) {
CHECK(resolver_.get());
// This job must be removed from resolver's |jobs_| now to make room for a
// new job with the same key in case one of the OnComplete callbacks decides
// to spawn one. Consequently, if the job was owned by |jobs_|, the job
// deletes itself when CompleteRequests is done.
std::unique_ptr<Job> self_deleter = resolver_->RemoveJob(this);
if (is_running()) {
proc_task_ = nullptr;
KillDnsTask();
mdns_task_ = nullptr;
// Signal dispatcher that a slot has opened.
resolver_->dispatcher_->OnJobFinished();
} else if (is_queued()) {
resolver_->dispatcher_->Cancel(handle_);
handle_.Reset();
}
if (num_active_requests() == 0) {
net_log_.AddEvent(NetLogEventType::CANCELLED);
net_log_.EndEventWithNetErrorCode(NetLogEventType::HOST_RESOLVER_IMPL_JOB,
OK);
return;
}
net_log_.EndEventWithNetErrorCode(NetLogEventType::HOST_RESOLVER_IMPL_JOB,
results.error());
DCHECK(!requests_.empty());
bool did_complete = (results.error() != ERR_NETWORK_CHANGED) &&
(results.error() != ERR_HOST_RESOLVER_QUEUE_TOO_LARGE);
if (did_complete && allow_cache) {
Key effective_key = key_;
effective_key.secure = secure;
resolver_->CacheResult(effective_key, results, ttl);
}
RecordJobHistograms(results.error());
// Complete all of the requests that were attached to the job and
// detach them.
while (!requests_.empty()) {
RequestImpl* req = requests_.head()->value();
req->RemoveFromList();
DCHECK_EQ(this, req->job());
// Update the net log and notify registered observers.
LogFinishRequest(req->source_net_log(), results.error());
if (did_complete) {
// Record effective total time from creation to completion.
resolver_->RecordTotalTime(
req->parameters().is_speculative, false /* from_cache */,
tick_clock_->NowTicks() - req->request_time());
}
if (results.error() == OK && !req->parameters().is_speculative) {
req->set_results(
results.CopyWithDefaultPort(req->request_host().port()));
}
req->OnJobCompleted(this, results.error());
// Check if the resolver was destroyed as a result of running the
// callback. If it was, we could continue, but we choose to bail.
if (!resolver_.get())
return;
}
}
void CompleteRequestsWithoutCache(const HostCache::Entry& results) {
CompleteRequests(results, base::TimeDelta(), false /* allow_cache */,
false /* secure */);
}
// Convenience wrapper for CompleteRequests in case of failure.
void CompleteRequestsWithError(int net_error) {
DCHECK_NE(OK, net_error);
CompleteRequests(
HostCache::Entry(net_error, HostCache::Entry::SOURCE_UNKNOWN),
base::TimeDelta(), true /* allow_cache */, false /* secure */);
}
RequestPriority priority() const override {
return priority_tracker_.highest_priority();
}
// Number of non-canceled requests in |requests_|.
size_t num_active_requests() const { return priority_tracker_.total_count(); }
bool is_dns_running() const { return !!dns_task_; }
bool is_mdns_running() const { return !!mdns_task_; }
bool is_proc_running() const { return !!proc_task_; }
base::WeakPtr<HostResolverManager> resolver_;
Key key_;
// Tracks the highest priority across |requests_|.
PriorityTracker priority_tracker_;
// Task runner used for HostResolverProc.
scoped_refptr<base::TaskRunner> proc_task_runner_;
bool had_non_speculative_request_;
// Number of slots occupied by this Job in resolver's PrioritizedDispatcher.
unsigned num_occupied_job_slots_;
// Result of DnsTask.
int dns_task_error_;
const base::TickClock* tick_clock_;
base::TimeTicks start_time_;
NetLogWithSource net_log_;
// Resolves the host using a HostResolverProc.
std::unique_ptr<ProcTask> proc_task_;
// Resolves the host using a DnsTransaction.
std::unique_ptr<DnsTask> dns_task_;
// Resolves the host using MDnsClient.
std::unique_ptr<HostResolverMdnsTask> mdns_task_;
// All Requests waiting for the result of this Job. Some can be canceled.
base::LinkedList<RequestImpl> requests_;
// A handle used in |HostResolverManager::dispatcher_|.
PrioritizedDispatcher::Handle handle_;
base::WeakPtrFactory<Job> weak_ptr_factory_;
};
//-----------------------------------------------------------------------------
HostResolverManager::HostResolverManager(const Options& options,
NetLog* net_log)
: max_queued_jobs_(0),
proc_params_(nullptr, options.max_retry_attempts),
net_log_(net_log),
received_dns_config_(false),
num_dns_failures_(0),
assume_ipv6_failure_on_wifi_(false),
use_local_ipv6_(false),
last_ipv6_probe_result_(true),
additional_resolver_flags_(0),
use_proctask_by_default_(false),
allow_fallback_to_proctask_(true),
url_request_context_(nullptr),
tick_clock_(base::DefaultTickClock::GetInstance()),
weak_ptr_factory_(this),
probe_weak_ptr_factory_(this) {
if (options.enable_caching)
cache_ = HostCache::CreateDefaultCache();
PrioritizedDispatcher::Limits job_limits = options.GetDispatcherLimits();
dispatcher_.reset(new PrioritizedDispatcher(job_limits));
max_queued_jobs_ = job_limits.total_jobs * 100u;
DCHECK_GE(dispatcher_->num_priorities(), static_cast<size_t>(NUM_PRIORITIES));
proc_task_runner_ = base::CreateTaskRunnerWithTraits(
{base::MayBlock(), priority_mode.Get(),
base::TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN});
#if defined(OS_WIN)
EnsureWinsockInit();
#endif
#if (defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_ANDROID)) || \
defined(OS_FUCHSIA)
RunLoopbackProbeJob();
#endif
NetworkChangeNotifier::AddIPAddressObserver(this);
NetworkChangeNotifier::AddConnectionTypeObserver(this);
NetworkChangeNotifier::AddDNSObserver(this);
#if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_OPENBSD) && \
!defined(OS_ANDROID)
EnsureDnsReloaderInit();
#endif
OnConnectionTypeChanged(NetworkChangeNotifier::GetConnectionType());
{
DnsConfig dns_config = GetBaseDnsConfig(false);
// Conservatively assume local IPv6 is needed when DnsConfig is not valid.
use_local_ipv6_ = !dns_config.IsValid() || dns_config.use_local_ipv6;
UpdateModeForHistogram(dns_config);
}
allow_fallback_to_proctask_ = !ConfigureAsyncDnsNoFallbackFieldTrial();
}
HostResolverManager::~HostResolverManager() {
DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
// Prevent the dispatcher from starting new jobs.
dispatcher_->SetLimitsToZero();
// It's now safe for Jobs to call KillDnsTask on destruction, because
// OnJobComplete will not start any new jobs.
jobs_.clear();
NetworkChangeNotifier::RemoveIPAddressObserver(this);
NetworkChangeNotifier::RemoveConnectionTypeObserver(this);
NetworkChangeNotifier::RemoveDNSObserver(this);
}
void HostResolverManager::SetDnsClient(std::unique_ptr<DnsClient> dns_client) {
DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
// DnsClient and config must be updated before aborting DnsTasks, since doing
// so may start new jobs.
dns_client_ = std::move(dns_client);
if (dns_client_ && !dns_client_->GetConfig() &&
num_dns_failures_ < kMaximumDnsFailures) {
dns_client_->SetConfig(GetBaseDnsConfig(false));
num_dns_failures_ = 0;
}
AbortDnsTasks(ERR_NETWORK_CHANGED, false /* fallback_only */);
DnsConfig dns_config;
if (!HaveDnsConfig())
// UpdateModeForHistogram() needs to know the DnsConfig when
// !HaveDnsConfig()
dns_config = GetBaseDnsConfig(false);
UpdateModeForHistogram(dns_config);
}
std::unique_ptr<HostResolver::ResolveHostRequest>
HostResolverManager::CreateRequest(
const HostPortPair& host,
const NetLogWithSource& net_log,
const base::Optional<ResolveHostParameters>& optional_parameters) {
DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
return std::make_unique<RequestImpl>(net_log, host, optional_parameters,
weak_ptr_factory_.GetWeakPtr());
}
std::unique_ptr<HostResolver::MdnsListener>
HostResolverManager::CreateMdnsListener(const HostPortPair& host,
DnsQueryType query_type) {
DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
DCHECK_NE(DnsQueryType::UNSPECIFIED, query_type);
auto listener =
std::make_unique<HostResolverMdnsListenerImpl>(host, query_type);
MDnsClient* client;
int rv = GetOrCreateMdnsClient(&client);
if (rv == OK) {
std::unique_ptr<net::MDnsListener> inner_listener = client->CreateListener(
DnsQueryTypeToQtype(query_type), host.host(), listener.get());
listener->set_inner_listener(std::move(inner_listener));
} else {
listener->set_initialization_error(rv);
}
return listener;
}
void HostResolverManager::SetDnsClientEnabled(bool enabled) {
DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
#if defined(ENABLE_BUILT_IN_DNS)
if (enabled && !dns_client_) {
SetDnsClient(DnsClient::CreateClient(net_log_));
} else if (!enabled && dns_client_) {
SetDnsClient(nullptr);
}
#endif
}
HostCache* HostResolverManager::GetHostCache() {
DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
return cache_.get();
}
bool HostResolverManager::HasCached(base::StringPiece hostname,
HostCache::Entry::Source* source_out,
HostCache::EntryStaleness* stale_out,
bool* secure_out) const {
DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
if (!cache_)
return false;
const HostCache::Key* key =
cache_->GetMatchingKey(hostname, source_out, stale_out);
if (key && secure_out != nullptr)
*secure_out = key->secure;
return !!key;
}
std::unique_ptr<base::Value> HostResolverManager::GetDnsConfigAsValue() const {
DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
// Check if async DNS is disabled.
if (!dns_client_.get())
return nullptr;
// Check if async DNS is enabled, but we currently have no configuration
// for it.
const DnsConfig* dns_config = dns_client_->GetConfig();
if (!dns_config)
return std::make_unique<base::DictionaryValue>();
return dns_config->ToValue();
}
size_t HostResolverManager::LastRestoredCacheSize() const {
DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
return cache_ ? cache_->last_restore_size() : 0;
}
size_t HostResolverManager::CacheSize() const {
DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
return cache_ ? cache_->size() : 0;
}
void HostResolverManager::SetNoIPv6OnWifi(bool no_ipv6_on_wifi) {
DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
assume_ipv6_failure_on_wifi_ = no_ipv6_on_wifi;
}
bool HostResolverManager::GetNoIPv6OnWifi() {
DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
return assume_ipv6_failure_on_wifi_;
}
void HostResolverManager::SetDnsConfigOverrides(
const DnsConfigOverrides& overrides) {
DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
if (dns_config_overrides_ == overrides)
return;
dns_config_overrides_ = overrides;
if (dns_client_.get())
UpdateDNSConfig(true);
}
void HostResolverManager::SetRequestContext(URLRequestContext* context) {
DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
if (context != url_request_context_) {
url_request_context_ = context;
}
}
const std::vector<DnsConfig::DnsOverHttpsServerConfig>*
HostResolverManager::GetDnsOverHttpsServersForTesting() const {
if (!dns_config_overrides_.dns_over_https_servers ||
dns_config_overrides_.dns_over_https_servers.value().empty()) {
return nullptr;
}
return &dns_config_overrides_.dns_over_https_servers.value();
}
void HostResolverManager::SetTickClockForTesting(
const base::TickClock* tick_clock) {
tick_clock_ = tick_clock;
cache_->set_tick_clock_for_testing(tick_clock);
}
void HostResolverManager::SetMaxQueuedJobsForTesting(size_t value) {
DCHECK_EQ(0u, dispatcher_->num_queued_jobs());
DCHECK_GE(value, 0u);
max_queued_jobs_ = value;
}
void HostResolverManager::SetHaveOnlyLoopbackAddresses(bool result) {
if (result) {
additional_resolver_flags_ |= HOST_RESOLVER_LOOPBACK_ONLY;
} else {
additional_resolver_flags_ &= ~HOST_RESOLVER_LOOPBACK_ONLY;
}
}
void HostResolverManager::SetMdnsSocketFactoryForTesting(
std::unique_ptr<MDnsSocketFactory> socket_factory) {
DCHECK(!mdns_client_);
mdns_socket_factory_ = std::move(socket_factory);
}
void HostResolverManager::SetMdnsClientForTesting(
std::unique_ptr<MDnsClient> client) {
mdns_client_ = std::move(client);
}
void HostResolverManager::SetBaseDnsConfigForTesting(
const DnsConfig& base_config) {
test_base_config_ = base_config;
UpdateDNSConfig(true);
}
void HostResolverManager::SetTaskRunnerForTesting(
scoped_refptr<base::TaskRunner> task_runner) {
proc_task_runner_ = std::move(task_runner);
}
int HostResolverManager::Resolve(RequestImpl* request) {
DCHECK_CALLED_ON_VALID_THREAD(thread_checker_);
// Request should not yet have a scheduled Job.
DCHECK(!request->job());
// Request may only be resolved once.
DCHECK(!request->complete());
// MDNS requests do not support skipping cache or stale lookups.
// TODO(crbug.com/926300): Either add support for skipping the MDNS cache, or
// merge to use the normal host cache for MDNS requests.
DCHECK(request->parameters().source != HostResolverSource::MULTICAST_DNS ||
request->parameters().cache_usage ==
ResolveHostParameters::CacheUsage::ALLOWED);
request->set_request_time(tick_clock_->NowTicks());
LogStartRequest(request->source_net_log(), request->request_host());
Key key;
base::Optional<HostCache::EntryStaleness> stale_info;
HostCache::Entry results = ResolveLocally(
request->request_host().host(), request->parameters().dns_query_type,
request->parameters().source, request->host_resolver_flags(),
request->parameters().cache_usage, request->source_net_log(), &key,
&stale_info);
if (results.error() != ERR_DNS_CACHE_MISS ||
request->parameters().source == HostResolverSource::LOCAL_ONLY) {
if (results.error() == OK && !request->parameters().is_speculative) {
request->set_results(
results.CopyWithDefaultPort(request->request_host().port()));
}
if (stale_info && !request->parameters().is_speculative)
request->set_stale_info(std::move(stale_info).value());
LogFinishRequest(request->source_net_log(), results.error());
RecordTotalTime(request->parameters().is_speculative, true /* from_cache */,
base::TimeDelta());
return results.error();
}
int rv = CreateAndStartJob(key, request);
// At this point, expect only async or errors.
DCHECK_NE(OK, rv);
return rv;
}
HostCache::Entry HostResolverManager::ResolveLocally(
const std::string& hostname,
DnsQueryType dns_query_type,
HostResolverSource source,
HostResolverFlags flags,
ResolveHostParameters::CacheUsage cache_usage,
const NetLogWithSource& source_net_log,
Key* out_key,
base::Optional<HostCache::EntryStaleness>* out_stale_info) {
DCHECK(out_stale_info);
*out_stale_info = base::nullopt;
IPAddress ip_address;
IPAddress* ip_address_ptr = nullptr;
if (ip_address.AssignFromIPLiteral(hostname)) {
ip_address_ptr = &ip_address;
} else {
// Check that the caller supplied a valid hostname to resolve. For
// MULTICAST_DNS, we are less restrictive.
// TODO(ericorth): Control validation based on an explicit flag rather
// than implicitly based on |source|.
const bool is_valid_hostname = source == HostResolverSource::MULTICAST_DNS
? IsValidUnrestrictedDNSDomain(hostname)
: IsValidDNSDomain(hostname);
if (!is_valid_hostname) {
return HostCache::Entry(ERR_NAME_NOT_RESOLVED,
HostCache::Entry::SOURCE_UNKNOWN);
}
}
// Build a key that identifies the request in the cache and in the
// outstanding jobs map. If this key is used in the future to store an entry
// in the cache, it will be modified first to indicate whether the result was
// obtained securely or not.
*out_key = GetEffectiveKeyForRequest(hostname, dns_query_type, source, flags,
ip_address_ptr, source_net_log);
// The result of |getaddrinfo| for empty hosts is inconsistent across systems.
// On Windows it gives the default interface's address, whereas on Linux it
// gives an error. We will make it fail on all platforms for consistency.
if (hostname.empty() || hostname.size() > kMaxHostLength) {
return HostCache::Entry(ERR_NAME_NOT_RESOLVED,
HostCache::Entry::SOURCE_UNKNOWN);
}
base::Optional<HostCache::Entry> resolved =
ResolveAsIP(*out_key, ip_address_ptr);
if (resolved)
return resolved.value();
// Special-case localhost names, as per the recommendations in
// https://tools.ietf.org/html/draft-west-let-localhost-be-localhost.
resolved = ServeLocalhost(*out_key);
if (resolved)
return resolved.value();
if (cache_usage == ResolveHostParameters::CacheUsage::ALLOWED ||
cache_usage == ResolveHostParameters::CacheUsage::STALE_ALLOWED) {
resolved = ServeFromCache(
*out_key,
cache_usage == ResolveHostParameters::CacheUsage::STALE_ALLOWED,
out_stale_info);
if (resolved) {
DCHECK(out_stale_info->has_value());
source_net_log.AddEvent(NetLogEventType::HOST_RESOLVER_IMPL_CACHE_HIT,
resolved.value().CreateNetLogCallback());
// |ServeFromCache()| will update |*stale_info| as needed.
return resolved.value();
}
DCHECK(!out_stale_info->has_value());
}
// TODO(szym): Do not do this if nsswitch.conf instructs not to.
// http://crbug.com/117655
resolved = ServeFromHosts(*out_key);
if (resolved) {
source_net_log.AddEvent(NetLogEventType::HOST_RESOLVER_IMPL_HOSTS_HIT,
resolved.value().CreateNetLogCallback());
return resolved.value();
}
return HostCache::Entry(ERR_DNS_CACHE_MISS, HostCache::Entry::SOURCE_UNKNOWN);
}
int HostResolverManager::CreateAndStartJob(const Key& key,
RequestImpl* request) {
auto jobit = jobs_.find(key);
Job* job;
if (jobit == jobs_.end()) {
auto new_job = std::make_unique<Job>(
weak_ptr_factory_.GetWeakPtr(), key, request->priority(),
proc_task_runner_, request->source_net_log(), tick_clock_);
job = new_job.get();
new_job->Schedule(false);
DCHECK(new_job->is_running() || new_job->is_queued());
// Check for queue overflow.
if (dispatcher_->num_queued_jobs() > max_queued_jobs_) {
Job* evicted = static_cast<Job*>(dispatcher_->EvictOldestLowest());
DCHECK(evicted);
if (evicted == new_job.get()) {
evicted->OnEvicted(false /* complete_asynchronously */);
LogFinishRequest(request->source_net_log(),
ERR_HOST_RESOLVER_QUEUE_TOO_LARGE);
return ERR_HOST_RESOLVER_QUEUE_TOO_LARGE;
} else {
// |evicted| could have waiting requests that will receive completion
// callbacks, so cleanup asynchronously to avoid reentrancy.
evicted->OnEvicted(true /* complete_asynchronously */);
}
}
DCHECK(new_job->is_running() || new_job->is_queued());
DCHECK(!jobs_[key]);
jobs_[key] = std::move(new_job);
} else {
job = jobit->second.get();
}
// Can't complete synchronously. Attach request and job to each other.
job->AddRequest(request);
return ERR_IO_PENDING;
}
base::Optional<HostCache::Entry> HostResolverManager::ResolveAsIP(
const Key& key,
const IPAddress* ip_address) {
if (ip_address == nullptr || !IsAddressType(key.dns_query_type))
return base::nullopt;
AddressFamily family = GetAddressFamily(*ip_address);
if (key.dns_query_type != DnsQueryType::UNSPECIFIED &&
key.dns_query_type != AddressFamilyToDnsQueryType(family)) {
// Don't return IPv6 addresses for IPv4 queries, and vice versa.
return HostCache::Entry(ERR_NAME_NOT_RESOLVED,
HostCache::Entry::SOURCE_UNKNOWN);
}
AddressList addresses = AddressList::CreateFromIPAddress(*ip_address, 0);
if (key.host_resolver_flags & HOST_RESOLVER_CANONNAME)
addresses.SetDefaultCanonicalName();
return HostCache::Entry(OK, std::move(addresses),
HostCache::Entry::SOURCE_UNKNOWN);
}
base::Optional<HostCache::Entry> HostResolverManager::ServeFromCache(
const Key& key,
bool allow_stale,
base::Optional<HostCache::EntryStaleness>* out_stale_info) {
DCHECK(out_stale_info);
*out_stale_info = base::nullopt;
if (!cache_.get())
return base::nullopt;
// Local-only requests search the cache for non-local-only results.
Key effective_key = key;
if (effective_key.host_resolver_source == HostResolverSource::LOCAL_ONLY)
effective_key.host_resolver_source = HostResolverSource::ANY;
const std::pair<const HostCache::Key, HostCache::Entry>* cache_result;
HostCache::EntryStaleness staleness;
if (allow_stale) {
cache_result = cache_->LookupStale(effective_key, tick_clock_->NowTicks(),
&staleness, true /* ignore_secure */);
} else {
cache_result = cache_->Lookup(effective_key, tick_clock_->NowTicks(),
true /* ignore_secure */);
staleness = HostCache::kNotStale;
}
if (!cache_result)
return base::nullopt;
*out_stale_info = std::move(staleness);
return cache_result->second;
}
base::Optional<HostCache::Entry> HostResolverManager::ServeFromHosts(
const Key& key) {
if (!HaveDnsConfig() || !IsAddressType(key.dns_query_type))
return base::nullopt;
// HOSTS lookups are case-insensitive.
std::string hostname = base::ToLowerASCII(key.hostname);
const DnsHosts& hosts = dns_client_->GetConfig()->hosts;
// If |address_family| is ADDRESS_FAMILY_UNSPECIFIED other implementations
// (glibc and c-ares) return the first matching line. We have more
// flexibility, but lose implicit ordering.
// We prefer IPv6 because "happy eyeballs" will fall back to IPv4 if
// necessary.
AddressList addresses;
if (key.dns_query_type == DnsQueryType::AAAA ||
key.dns_query_type == DnsQueryType::UNSPECIFIED) {
auto it = hosts.find(DnsHostsKey(hostname, ADDRESS_FAMILY_IPV6));
if (it != hosts.end())
addresses.push_back(IPEndPoint(it->second, 0));
}
if (key.dns_query_type == DnsQueryType::A ||
key.dns_query_type == DnsQueryType::UNSPECIFIED) {
auto it = hosts.find(DnsHostsKey(hostname, ADDRESS_FAMILY_IPV4));
if (it != hosts.end())
addresses.push_back(IPEndPoint(it->second, 0));
}
// If got only loopback addresses and the family was restricted, resolve
// again, without restrictions. See SystemHostResolverCall for rationale.
if ((key.host_resolver_flags &
HOST_RESOLVER_DEFAULT_FAMILY_SET_DUE_TO_NO_IPV6) &&
IsAllIPv4Loopback(addresses)) {
Key new_key(key);
new_key.dns_query_type = DnsQueryType::UNSPECIFIED;
new_key.host_resolver_flags &=
~HOST_RESOLVER_DEFAULT_FAMILY_SET_DUE_TO_NO_IPV6;
return ServeFromHosts(new_key);
}
if (!addresses.empty()) {
return HostCache::Entry(OK, std::move(addresses),
HostCache::Entry::SOURCE_HOSTS);
}
return base::nullopt;
}
base::Optional<HostCache::Entry> HostResolverManager::ServeLocalhost(
const Key& key) {
AddressList resolved_addresses;
if (!IsAddressType(key.dns_query_type) ||
!ResolveLocalHostname(key.hostname, &resolved_addresses)) {
return base::nullopt;
}
AddressList filtered_addresses;
for (const auto& address : resolved_addresses) {
// Include the address if:
// - caller didn't specify an address family, or
// - caller specifically asked for the address family of this address, or
// - this is an IPv6 address and caller specifically asked for IPv4 due
// to lack of detected IPv6 support. (See SystemHostResolverCall for
// rationale).
if (key.dns_query_type == DnsQueryType::UNSPECIFIED ||
HostResolver::DnsQueryTypeToAddressFamily(key.dns_query_type) ==
address.GetFamily() ||
(address.GetFamily() == ADDRESS_FAMILY_IPV6 &&
key.dns_query_type == DnsQueryType::A &&
(key.host_resolver_flags &
HOST_RESOLVER_DEFAULT_FAMILY_SET_DUE_TO_NO_IPV6))) {
filtered_addresses.push_back(address);
}
}
return HostCache::Entry(OK, std::move(filtered_addresses),
HostCache::Entry::SOURCE_UNKNOWN);
}
void HostResolverManager::CacheResult(const Key& key,
const HostCache::Entry& entry,
base::TimeDelta ttl) {
// Don't cache an error unless it has a positive TTL.
if (cache_.get() && (entry.error() == OK || ttl > base::TimeDelta()))
cache_->Set(key, entry, tick_clock_->NowTicks(), ttl);
}
// Record time from Request creation until a valid DNS response.
void HostResolverManager::RecordTotalTime(bool speculative,
bool from_cache,
base::TimeDelta duration) const {
if (!speculative) {
UMA_HISTOGRAM_LONG_TIMES_100("Net.DNS.TotalTime", duration);
switch (mode_for_histogram_) {
case MODE_FOR_HISTOGRAM_SYSTEM:
UMA_HISTOGRAM_MEDIUM_TIMES("Net.DNS.TotalTimeTyped.System", duration);
break;
case MODE_FOR_HISTOGRAM_SYSTEM_SUPPORTS_DOH:
UMA_HISTOGRAM_MEDIUM_TIMES("Net.DNS.TotalTimeTyped.SystemSupportsDoh",
duration);
break;
case MODE_FOR_HISTOGRAM_SYSTEM_PRIVATE_DNS:
UMA_HISTOGRAM_MEDIUM_TIMES("Net.DNS.TotalTimeTyped.SystemPrivate",
duration);
break;
case MODE_FOR_HISTOGRAM_ASYNC_DNS:
UMA_HISTOGRAM_MEDIUM_TIMES("Net.DNS.TotalTimeTyped.Async", duration);
break;
case MODE_FOR_HISTOGRAM_ASYNC_DNS_PRIVATE_SUPPORTS_DOH:
UMA_HISTOGRAM_MEDIUM_TIMES(
"Net.DNS.TotalTimeTyped.AsyncPrivateSupportsDoh", duration);
break;
}
if (!from_cache)
UMA_HISTOGRAM_LONG_TIMES_100("Net.DNS.TotalTimeNotCached", duration);
}
}
std::unique_ptr<HostResolverManager::Job> HostResolverManager::RemoveJob(
Job* job) {
DCHECK(job);
std::unique_ptr<Job> retval;
auto it = jobs_.find(job->key());
if (it != jobs_.end() && it->second.get() == job) {
it->second.swap(retval);
jobs_.erase(it);
}
return retval;
}
HostResolverManager::Key HostResolverManager::GetEffectiveKeyForRequest(
const std::string& hostname,
DnsQueryType dns_query_type,
HostResolverSource source,
HostResolverFlags flags,
const IPAddress* ip_address,
const NetLogWithSource& net_log) {
HostResolverFlags effective_flags = flags | additional_resolver_flags_;
DnsQueryType effective_query_type = dns_query_type;
if (effective_query_type == DnsQueryType::UNSPECIFIED &&
// When resolving IPv4 literals, there's no need to probe for IPv6.
// When resolving IPv6 literals, there's no benefit to artificially
// limiting our resolution based on a probe. Prior logic ensures
// that this query is UNSPECIFIED (see effective_query_type check above)
// so the code requesting the resolution should be amenable to receiving a
// IPv6 resolution.
!use_local_ipv6_ && ip_address == nullptr && !IsIPv6Reachable(net_log)) {
effective_query_type = DnsQueryType::A;
effective_flags |= HOST_RESOLVER_DEFAULT_FAMILY_SET_DUE_TO_NO_IPV6;
}
return Key(hostname, effective_query_type, effective_flags, source);
}
bool HostResolverManager::IsIPv6Reachable(const NetLogWithSource& net_log) {
// Don't bother checking if the device is on WiFi and IPv6 is assumed to not
// work on WiFi.
if (assume_ipv6_failure_on_wifi_ &&
NetworkChangeNotifier::GetConnectionType() ==
NetworkChangeNotifier::CONNECTION_WIFI) {
return false;
}
// Cache the result for kIPv6ProbePeriodMs (measured from after
// IsGloballyReachable() completes).
bool cached = true;
if ((tick_clock_->NowTicks() - last_ipv6_probe_time_).InMilliseconds() >
kIPv6ProbePeriodMs) {
last_ipv6_probe_result_ =
IsGloballyReachable(IPAddress(kIPv6ProbeAddress), net_log);
last_ipv6_probe_time_ = tick_clock_->NowTicks();
cached = false;
}
net_log.AddEvent(NetLogEventType::HOST_RESOLVER_IMPL_IPV6_REACHABILITY_CHECK,
base::Bind(&NetLogIPv6AvailableCallback,
last_ipv6_probe_result_, cached));
return last_ipv6_probe_result_;
}
bool HostResolverManager::IsGloballyReachable(const IPAddress& dest,
const NetLogWithSource& net_log) {
std::unique_ptr<DatagramClientSocket> socket(
ClientSocketFactory::GetDefaultFactory()->CreateDatagramClientSocket(
DatagramSocket::DEFAULT_BIND, net_log.net_log(), net_log.source()));
int rv = socket->Connect(IPEndPoint(dest, 53));
if (rv != OK)
return false;
IPEndPoint endpoint;
rv = socket->GetLocalAddress(&endpoint);
if (rv != OK)
return false;
DCHECK_EQ(ADDRESS_FAMILY_IPV6, endpoint.GetFamily());
const IPAddress& address = endpoint.address();
bool is_link_local =
(address.bytes()[0] == 0xFE) && ((address.bytes()[1] & 0xC0) == 0x80);
if (is_link_local)
return false;
const uint8_t kTeredoPrefix[] = {0x20, 0x01, 0, 0};
if (IPAddressStartsWith(address, kTeredoPrefix))
return false;
return true;
}
void HostResolverManager::RunLoopbackProbeJob() {
// Run this asynchronously as it can take 40-100ms and should not block
// initialization.
base::PostTaskWithTraitsAndReplyWithResult(
FROM_HERE,
{base::MayBlock(), base::TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN},
base::BindOnce(&HaveOnlyLoopbackAddresses),
base::BindOnce(&HostResolverManager::SetHaveOnlyLoopbackAddresses,
weak_ptr_factory_.GetWeakPtr()));
}
void HostResolverManager::AbortAllInProgressJobs() {
// In Abort, a Request callback could spawn new Jobs with matching keys, so
// first collect and remove all running jobs from |jobs_|.
std::vector<std::unique_ptr<Job>> jobs_to_abort;
for (auto it = jobs_.begin(); it != jobs_.end();) {
Job* job = it->second.get();
if (job->is_running()) {
jobs_to_abort.push_back(std::move(it->second));
jobs_.erase(it++);
} else {
DCHECK(job->is_queued());
++it;
}
}
// Pause the dispatcher so it won't start any new dispatcher jobs while
// aborting the old ones. This is needed so that it won't start the second
// DnsTransaction for a job in |jobs_to_abort| if the DnsConfig just became
// invalid.
PrioritizedDispatcher::Limits limits = dispatcher_->GetLimits();
dispatcher_->SetLimits(
PrioritizedDispatcher::Limits(limits.reserved_slots.size(), 0));
// Life check to bail once |this| is deleted.
base::WeakPtr<HostResolverManager> self = weak_ptr_factory_.GetWeakPtr();
// Then Abort them.
for (size_t i = 0; self.get() && i < jobs_to_abort.size(); ++i) {
jobs_to_abort[i]->Abort();
}
if (self)
dispatcher_->SetLimits(limits);
}
void HostResolverManager::AbortDnsTasks(int error, bool fallback_only) {
// Aborting jobs potentially modifies |jobs_| and may even delete some jobs.
// Create safe closures of all current jobs.
std::vector<base::OnceClosure> job_abort_closures;
for (auto& job : jobs_) {
job_abort_closures.push_back(
job.second->GetAbortDnsTaskClosure(error, fallback_only));
}
// Pause the dispatcher so it won't start any new dispatcher jobs while
// aborting the old ones. This is needed so that it won't start the second
// DnsTransaction for a job if the DnsConfig just changed.
PrioritizedDispatcher::Limits limits = dispatcher_->GetLimits();
dispatcher_->SetLimits(
PrioritizedDispatcher::Limits(limits.reserved_slots.size(), 0));
for (base::OnceClosure& closure : job_abort_closures)
std::move(closure).Run();
dispatcher_->SetLimits(limits);
}
void HostResolverManager::TryServingAllJobsFromHosts() {
if (!HaveDnsConfig())
return;
// TODO(szym): Do not do this if nsswitch.conf instructs not to.
// http://crbug.com/117655
// Life check to bail once |this| is deleted.
base::WeakPtr<HostResolverManager> self = weak_ptr_factory_.GetWeakPtr();
for (auto it = jobs_.begin(); self.get() && it != jobs_.end();) {
Job* job = it->second.get();
++it;
// This could remove |job| from |jobs_|, but iterator will remain valid.
job->ServeFromHosts();
}
}
void HostResolverManager::OnIPAddressChanged() {
last_ipv6_probe_time_ = base::TimeTicks();
// Abandon all ProbeJobs.
probe_weak_ptr_factory_.InvalidateWeakPtrs();
if (cache_.get())
cache_->OnNetworkChange();
#if (defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_ANDROID)) || \
defined(OS_FUCHSIA)
RunLoopbackProbeJob();
#endif
AbortAllInProgressJobs();
// |this| may be deleted inside AbortAllInProgressJobs().
}
void HostResolverManager::OnConnectionTypeChanged(
NetworkChangeNotifier::ConnectionType type) {
proc_params_.unresponsive_delay =
GetTimeDeltaForConnectionTypeFromFieldTrialOrDefault(
"DnsUnresponsiveDelayMsByConnectionType",
ProcTaskParams::kDnsDefaultUnresponsiveDelay, type);
}
void HostResolverManager::OnInitialDNSConfigRead() {
UpdateDNSConfig(false);
}
void HostResolverManager::OnDNSChanged() {
// Ignore changes if we're using a test config or if we have overriding
// configuration that overrides everything from the base config.
if (test_base_config_ || dns_config_overrides_.OverridesEverything())
return;
UpdateDNSConfig(true);
}
DnsConfig HostResolverManager::GetBaseDnsConfig(bool log_to_net_log) {
DnsConfig dns_config;
// Skip retrieving the base config if all values will be overridden.
if (!dns_config_overrides_.OverridesEverything()) {
if (test_base_config_) {
dns_config = test_base_config_.value();
} else {
NetworkChangeNotifier::GetDnsConfig(&dns_config);
}
if (log_to_net_log && net_log_) {
net_log_->AddGlobalEntry(
NetLogEventType::DNS_CONFIG_CHANGED,
base::BindRepeating(&NetLogDnsConfigCallback, &dns_config));
}
// TODO(szym): Remove once http://crbug.com/137914 is resolved.
received_dns_config_ = dns_config.IsValid();
}
return dns_config_overrides_.ApplyOverrides(dns_config);
}
void HostResolverManager::UpdateDNSConfig(bool config_changed) {
DnsConfig dns_config = GetBaseDnsConfig(true);
// Conservatively assume local IPv6 is needed when DnsConfig is not valid.
use_local_ipv6_ = !dns_config.IsValid() || dns_config.use_local_ipv6;
num_dns_failures_ = 0;
// We want a new DnsSession in place, before we Abort running Jobs, so that
// the newly started jobs use the new config.
if (dns_client_.get()) {
// Make sure that if the update is an initial read, not a change, there
// wasn't already a DnsConfig or it's the same one.
DCHECK(config_changed || !dns_client_->GetConfig() ||
dns_client_->GetConfig()->Equals(dns_config));
dns_client_->SetConfig(dns_config);
}
use_proctask_by_default_ = false;
if (config_changed) {
// If the DNS server has changed, existing cached info could be wrong so we
// have to expire our internal cache :( Note that OS level DNS caches, such
// as NSCD's cache should be dropped automatically by the OS when
// resolv.conf changes so we don't need to do anything to clear that cache.
if (cache_.get())
cache_->OnNetworkChange();
// Life check to bail once |this| is deleted.
base::WeakPtr<HostResolverManager> self = weak_ptr_factory_.GetWeakPtr();
// Existing jobs will have been sent to the original server so they need to
// be aborted.
AbortAllInProgressJobs();
// |this| may be deleted inside AbortAllInProgressJobs().
if (self.get())
TryServingAllJobsFromHosts();
}
UpdateModeForHistogram(dns_config);
}
bool HostResolverManager::HaveDnsConfig() const {
// Use DnsClient only if it's fully configured and there is no override by
// ScopedDefaultHostResolverProc.
// The alternative is to use NetworkChangeNotifier to override DnsConfig,
// but that would introduce construction order requirements for NCN and SDHRP.
return dns_client_ && dns_client_->GetConfig() &&
(proc_params_.resolver_proc || !HostResolverProc::GetDefault());
}
void HostResolverManager::OnDnsTaskResolve() {
DCHECK(dns_client_);
num_dns_failures_ = 0;
}
void HostResolverManager::OnFallbackResolve(int dns_task_error) {
DCHECK(dns_client_);
DCHECK_NE(OK, dns_task_error);
++num_dns_failures_;
if (num_dns_failures_ < kMaximumDnsFailures)
return;
// Force fallback until the next DNS change. Must be done before aborting
// DnsTasks, since doing so may start new jobs. Do not fully clear out or
// disable the DnsClient as some requests (e.g. those specifying DNS source)
// are not allowed to fallback and will continue using DnsTask.
use_proctask_by_default_ = true;
// Fallback all fallback-allowed DnsTasks to ProcTasks.
AbortDnsTasks(ERR_FAILED, true /* fallback_only */);
}
int HostResolverManager::GetOrCreateMdnsClient(MDnsClient** out_client) {
#if BUILDFLAG(ENABLE_MDNS)
if (!mdns_client_) {
if (!mdns_socket_factory_)
mdns_socket_factory_ = std::make_unique<MDnsSocketFactoryImpl>(net_log_);
mdns_client_ = MDnsClient::CreateDefault();
}
int rv = OK;
if (!mdns_client_->IsListening())
rv = mdns_client_->StartListening(mdns_socket_factory_.get());
DCHECK_NE(ERR_IO_PENDING, rv);
DCHECK(rv != OK || mdns_client_->IsListening());
if (rv == OK)
*out_client = mdns_client_.get();
return rv;
#else
// Should not request MDNS resoltuion unless MDNS is enabled.
NOTREACHED();
return ERR_UNEXPECTED;
#endif
}
void HostResolverManager::UpdateModeForHistogram(const DnsConfig& dns_config) {
// Resolving with Async DNS resolver?
if (HaveDnsConfig()) {
mode_for_histogram_ = MODE_FOR_HISTOGRAM_ASYNC_DNS;
for (const auto& dns_server : dns_client_->GetConfig()->nameservers) {
if (DnsServerSupportsDoh(dns_server.address())) {
mode_for_histogram_ = MODE_FOR_HISTOGRAM_ASYNC_DNS_PRIVATE_SUPPORTS_DOH;
break;
}
}
} else {
mode_for_histogram_ = MODE_FOR_HISTOGRAM_SYSTEM;
for (const auto& dns_server : dns_config.nameservers) {
if (DnsServerSupportsDoh(dns_server.address())) {
mode_for_histogram_ = MODE_FOR_HISTOGRAM_SYSTEM_SUPPORTS_DOH;
break;
}
}
#if defined(OS_ANDROID)
if (base::android::BuildInfo::GetInstance()->sdk_int() >=
base::android::SDK_VERSION_P) {
std::vector<IPEndPoint> dns_servers;
if (net::android::GetDnsServers(&dns_servers) ==
internal::CONFIG_PARSE_POSIX_PRIVATE_DNS_ACTIVE) {
mode_for_histogram_ = MODE_FOR_HISTOGRAM_SYSTEM_PRIVATE_DNS;
}
}
#endif // defined(OS_ANDROID)
}
}
HostResolverManager::RequestImpl::~RequestImpl() {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
if (job_)
job_->CancelRequest(this);
}
void HostResolverManager::RequestImpl::ChangeRequestPriority(
RequestPriority priority) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
DCHECK(job_);
job_->ChangeRequestPriority(this, priority);
}
} // namespace net