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cobalt / cobalt / 0be0de584ed705b4c1ad6e08ab940973442529b5 / . / src / net / base / host_resolver_impl.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/base/host_resolver_impl.h"
#if defined(OS_WIN)
#include <Winsock2.h>
#elif defined(OS_POSIX)
#include <netdb.h>
#endif
#include <cmath>
#include <utility>
#include <vector>
#include "base/basictypes.h"
#include "base/bind.h"
#include "base/bind_helpers.h"
#include "base/callback.h"
#include "base/compiler_specific.h"
#include "base/debug/debugger.h"
#include "base/debug/stack_trace.h"
#include "base/message_loop_proxy.h"
#include "base/metrics/field_trial.h"
#include "base/metrics/histogram.h"
#include "base/stl_util.h"
#include "base/string_util.h"
#include "base/threading/worker_pool.h"
#include "base/time.h"
#include "base/utf_string_conversions.h"
#include "base/values.h"
#include "net/base/address_family.h"
#include "net/base/address_list.h"
#include "net/base/dns_reloader.h"
#include "net/base/host_port_pair.h"
#include "net/base/host_resolver_proc.h"
#include "net/base/net_errors.h"
#include "net/base/net_log.h"
#include "net/base/net_util.h"
#include "net/dns/address_sorter.h"
#include "net/dns/dns_client.h"
#include "net/dns/dns_config_service.h"
#include "net/dns/dns_protocol.h"
#include "net/dns/dns_response.h"
#include "net/dns/dns_transaction.h"
#include "nb/memory_scope.h"
#if defined(OS_WIN)
#include "net/base/winsock_init.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;
// Number of consecutive failures of DnsTask (with successful fallback) before
// the DnsClient is disabled until the next DNS change.
const unsigned kMaximumDnsFailures = 16;
// We use a separate histogram name for each platform to facilitate the
// display of error codes by their symbolic name (since each platform has
// different mappings).
const char kOSErrorsForGetAddrinfoHistogramName[] =
#if defined(OS_WIN)
"Net.OSErrorsForGetAddrinfo_Win";
#elif defined(OS_MACOSX)
"Net.OSErrorsForGetAddrinfo_Mac";
#elif defined(OS_LINUX)
"Net.OSErrorsForGetAddrinfo_Linux";
#else
"Net.OSErrorsForGetAddrinfo";
#endif
#if !defined(OS_STARBOARD)
// Gets a list of the likely error codes that getaddrinfo() can return
// (non-exhaustive). These are the error codes that we will track via
// a histogram.
std::vector<int> GetAllGetAddrinfoOSErrors() {
int os_errors[] = {
#if defined(OS_POSIX)
#if !defined(OS_FREEBSD)
#if !defined(OS_ANDROID)
// EAI_ADDRFAMILY has been declared obsolete in Android's and
// FreeBSD's netdb.h.
EAI_ADDRFAMILY,
#endif
// EAI_NODATA has been declared obsolete in FreeBSD's netdb.h.
EAI_NODATA,
#endif
EAI_AGAIN,
EAI_BADFLAGS,
EAI_FAIL,
EAI_FAMILY,
EAI_MEMORY,
EAI_NONAME,
EAI_SERVICE,
EAI_SOCKTYPE,
EAI_SYSTEM,
#elif defined(OS_WIN)
// See: http://msdn.microsoft.com/en-us/library/ms738520(VS.85).aspx
WSA_NOT_ENOUGH_MEMORY,
WSAEAFNOSUPPORT,
WSAEINVAL,
WSAESOCKTNOSUPPORT,
WSAHOST_NOT_FOUND,
WSANO_DATA,
WSANO_RECOVERY,
WSANOTINITIALISED,
WSATRY_AGAIN,
WSATYPE_NOT_FOUND,
// The following are not in doc, but might be to appearing in results :-(.
WSA_INVALID_HANDLE,
#endif
};
// Ensure all errors are positive, as histogram only tracks positive values.
for (size_t i = 0; i < arraysize(os_errors); ++i) {
os_errors[i] = std::abs(os_errors[i]);
}
return base::CustomHistogram::ArrayToCustomRanges(os_errors,
arraysize(os_errors));
}
#endif // defined(OS_STARBOARD)
enum DnsResolveStatus {
RESOLVE_STATUS_DNS_SUCCESS = 0,
RESOLVE_STATUS_PROC_SUCCESS,
RESOLVE_STATUS_FAIL,
RESOLVE_STATUS_SUSPECT_NETBIOS,
RESOLVE_STATUS_MAX
};
void UmaAsyncDnsResolveStatus(DnsResolveStatus result) {
UMA_HISTOGRAM_ENUMERATION("AsyncDNS.ResolveStatus",
result,
RESOLVE_STATUS_MAX);
}
bool ResemblesNetBIOSName(const std::string& hostname) {
return (hostname.size() < 16) && (hostname.find('.') == std::string::npos);
}
// 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[hostname.size() - 1] == '.') {
return hostname.size() > kSuffixLen &&
!hostname.compare(hostname.size() - kSuffixLen, kSuffixLen, kSuffix);
}
return hostname.size() > kSuffixLenTrimmed &&
!hostname.compare(hostname.size() - kSuffixLenTrimmed, kSuffixLenTrimmed,
kSuffix, kSuffixLenTrimmed);
}
// Provide a common macro to simplify code and readability. We must use a
// macro as the underlying HISTOGRAM macro creates static variables.
#define DNS_HISTOGRAM(name, time) UMA_HISTOGRAM_CUSTOM_TIMES(name, time, \
base::TimeDelta::FromMilliseconds(1), base::TimeDelta::FromHours(1), 100)
// A macro to simplify code and readability.
#define DNS_HISTOGRAM_BY_PRIORITY(basename, priority, time) \
do { \
switch (priority) { \
case HIGHEST: DNS_HISTOGRAM(basename "_HIGHEST", time); break; \
case MEDIUM: DNS_HISTOGRAM(basename "_MEDIUM", time); break; \
case LOW: DNS_HISTOGRAM(basename "_LOW", time); break; \
case LOWEST: DNS_HISTOGRAM(basename "_LOWEST", time); break; \
case IDLE: DNS_HISTOGRAM(basename "_IDLE", time); break; \
default: NOTREACHED(); break; \
} \
DNS_HISTOGRAM(basename, time); \
} while (0)
// Record time from Request creation until a valid DNS response.
void RecordTotalTime(bool had_dns_config,
bool speculative,
base::TimeDelta duration) {
if (had_dns_config) {
if (speculative) {
DNS_HISTOGRAM("AsyncDNS.TotalTime_speculative", duration);
} else {
DNS_HISTOGRAM("AsyncDNS.TotalTime", duration);
}
} else {
if (speculative) {
DNS_HISTOGRAM("DNS.TotalTime_speculative", duration);
} else {
DNS_HISTOGRAM("DNS.TotalTime", duration);
}
}
}
void RecordTTL(base::TimeDelta ttl) {
UMA_HISTOGRAM_CUSTOM_TIMES("AsyncDNS.TTL", ttl,
base::TimeDelta::FromSeconds(1),
base::TimeDelta::FromDays(1), 100);
}
//-----------------------------------------------------------------------------
// Wraps call to SystemHostResolverProc as an instance of HostResolverProc.
// TODO(szym): This should probably be declared in host_resolver_proc.h.
class CallSystemHostResolverProc : public HostResolverProc {
public:
CallSystemHostResolverProc() : HostResolverProc(NULL) {}
virtual int Resolve(const std::string& hostname,
AddressFamily address_family,
HostResolverFlags host_resolver_flags,
AddressList* addr_list,
int* os_error) override {
return SystemHostResolverProc(hostname,
address_family,
host_resolver_flags,
addr_list,
os_error);
}
protected:
virtual ~CallSystemHostResolverProc() {}
};
AddressList EnsurePortOnAddressList(const AddressList& list, uint16 port) {
if (list.empty() || list.front().port() == port)
return list;
return AddressList::CopyWithPort(list, port);
}
// Creates NetLog parameters when the resolve failed.
base::Value* NetLogProcTaskFailedCallback(uint32 attempt_number,
int net_error,
int os_error,
NetLog::LogLevel /* log_level */) {
DictionaryValue* dict = new 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_POSIX)
dict->SetString("os_error_string", gai_strerror(os_error));
#elif defined(OS_WIN)
// Map the error code to a human-readable string.
LPWSTR error_string = NULL;
int size = FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER |
FORMAT_MESSAGE_FROM_SYSTEM,
0, // Use the internal message table.
os_error,
0, // Use default language.
(LPWSTR)&error_string,
0, // Buffer size.
0); // Arguments (unused).
dict->SetString("os_error_string", WideToUTF8(error_string));
LocalFree(error_string);
#endif
}
return dict;
}
// Creates NetLog parameters when the DnsTask failed.
base::Value* NetLogDnsTaskFailedCallback(int net_error,
int dns_error,
NetLog::LogLevel /* log_level */) {
DictionaryValue* dict = new DictionaryValue();
dict->SetInteger("net_error", net_error);
if (dns_error)
dict->SetInteger("dns_error", dns_error);
return dict;
};
// Creates NetLog parameters containing the information in a RequestInfo object,
// along with the associated NetLog::Source.
base::Value* NetLogRequestInfoCallback(const NetLog::Source& source,
const HostResolver::RequestInfo* info,
NetLog::LogLevel /* log_level */) {
DictionaryValue* dict = new DictionaryValue();
source.AddToEventParameters(dict);
dict->SetString("host", info->host_port_pair().ToString());
dict->SetInteger("address_family",
static_cast<int>(info->address_family()));
dict->SetBoolean("allow_cached_response", info->allow_cached_response());
dict->SetBoolean("is_speculative", info->is_speculative());
dict->SetInteger("priority", info->priority());
return dict;
}
// Creates NetLog parameters for the creation of a HostResolverImpl::Job.
base::Value* NetLogJobCreationCallback(const NetLog::Source& source,
const std::string* host,
NetLog::LogLevel /* log_level */) {
DictionaryValue* dict = new DictionaryValue();
source.AddToEventParameters(dict);
dict->SetString("host", *host);
return dict;
}
// Creates NetLog parameters for HOST_RESOLVER_IMPL_JOB_ATTACH/DETACH events.
base::Value* NetLogJobAttachCallback(const NetLog::Source& source,
RequestPriority priority,
NetLog::LogLevel /* log_level */) {
DictionaryValue* dict = new DictionaryValue();
source.AddToEventParameters(dict);
dict->SetInteger("priority", priority);
return dict;
}
// Creates NetLog parameters for the DNS_CONFIG_CHANGED event.
base::Value* NetLogDnsConfigCallback(const DnsConfig* config,
NetLog::LogLevel /* log_level */) {
return config->ToValue();
}
// The logging routines are defined here because some requests are resolved
// without a Request object.
// Logs when a request has just been started.
void LogStartRequest(const BoundNetLog& source_net_log,
const BoundNetLog& request_net_log,
const HostResolver::RequestInfo& info) {
source_net_log.BeginEvent(
NetLog::TYPE_HOST_RESOLVER_IMPL,
request_net_log.source().ToEventParametersCallback());
request_net_log.BeginEvent(
NetLog::TYPE_HOST_RESOLVER_IMPL_REQUEST,
base::Bind(&NetLogRequestInfoCallback, source_net_log.source(), &info));
}
// Logs when a request has just completed (before its callback is run).
void LogFinishRequest(const BoundNetLog& source_net_log,
const BoundNetLog& request_net_log,
const HostResolver::RequestInfo& info,
int net_error) {
request_net_log.EndEventWithNetErrorCode(
NetLog::TYPE_HOST_RESOLVER_IMPL_REQUEST, net_error);
source_net_log.EndEvent(NetLog::TYPE_HOST_RESOLVER_IMPL);
}
// Logs when a request has been cancelled.
void LogCancelRequest(const BoundNetLog& source_net_log,
const BoundNetLog& request_net_log,
const HostResolverImpl::RequestInfo& info) {
request_net_log.AddEvent(NetLog::TYPE_CANCELLED);
request_net_log.EndEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_REQUEST);
source_net_log.EndEvent(NetLog::TYPE_HOST_RESOLVER_IMPL);
}
//-----------------------------------------------------------------------------
// 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];
};
} // namespace
//-----------------------------------------------------------------------------
// Holds the data for a request that could not be completed synchronously.
// It is owned by a Job. Canceled Requests are only marked as canceled rather
// than removed from the Job's |requests_| list.
class HostResolverImpl::Request {
public:
Request(const BoundNetLog& source_net_log,
const BoundNetLog& request_net_log,
const RequestInfo& info,
const CompletionCallback& callback,
AddressList* addresses)
: source_net_log_(source_net_log),
request_net_log_(request_net_log),
info_(info),
job_(NULL),
callback_(callback),
addresses_(addresses),
request_time_(base::TimeTicks::Now()) {
}
// Mark the request as canceled.
void MarkAsCanceled() {
job_ = NULL;
addresses_ = NULL;
callback_.Reset();
}
bool was_canceled() const {
return callback_.is_null();
}
void set_job(Job* job) {
DCHECK(job);
// Identify which job the request is waiting on.
job_ = job;
}
// Prepare final AddressList and call completion callback.
void OnComplete(int error, const AddressList& addr_list) {
DCHECK(!was_canceled());
if (error == OK)
*addresses_ = EnsurePortOnAddressList(addr_list, info_.port());
CompletionCallback callback = callback_;
MarkAsCanceled();
callback.Run(error);
}
Job* job() const {
return job_;
}
// NetLog for the source, passed in HostResolver::Resolve.
const BoundNetLog& source_net_log() {
return source_net_log_;
}
// NetLog for this request.
const BoundNetLog& request_net_log() {
return request_net_log_;
}
const RequestInfo& info() const {
return info_;
}
base::TimeTicks request_time() const {
return request_time_;
}
private:
BoundNetLog source_net_log_;
BoundNetLog request_net_log_;
// The request info that started the request.
RequestInfo info_;
// The resolve job that this request is dependent on.
Job* job_;
// The user's callback to invoke when the request completes.
CompletionCallback callback_;
// The address list to save result into.
AddressList* addresses_;
const base::TimeTicks request_time_;
DISALLOW_COPY_AND_ASSIGN(Request);
};
//------------------------------------------------------------------------------
// Calls HostResolverProc on the WorkerPool. Performs retries if necessary.
//
// 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 HostResolverImpl::ProcTask
: public base::RefCountedThreadSafe<HostResolverImpl::ProcTask> {
public:
typedef base::Callback<void(int net_error,
const AddressList& addr_list)> Callback;
ProcTask(const Key& key,
const ProcTaskParams& params,
const Callback& callback,
const BoundNetLog& job_net_log)
: key_(key),
params_(params),
callback_(callback),
origin_loop_(base::MessageLoopProxy::current()),
attempt_number_(0),
completed_attempt_number_(0),
completed_attempt_error_(ERR_UNEXPECTED),
had_non_speculative_request_(false),
net_log_(job_net_log) {
if (!params_.resolver_proc)
params_.resolver_proc = HostResolverProc::GetDefault();
// If default is unset, use the system proc.
if (!params_.resolver_proc)
params_.resolver_proc = new CallSystemHostResolverProc();
}
void Start() {
DCHECK(origin_loop_->BelongsToCurrentThread());
net_log_.BeginEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_PROC_TASK);
StartLookupAttempt();
}
// Cancels this ProcTask. It will be orphaned. Any outstanding resolve
// attempts running on worker threads will continue running. Only once all the
// attempts complete will the final reference to this ProcTask be released.
void Cancel() {
DCHECK(origin_loop_->BelongsToCurrentThread());
if (was_canceled() || was_completed())
return;
callback_.Reset();
net_log_.EndEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_PROC_TASK);
}
void set_had_non_speculative_request() {
DCHECK(origin_loop_->BelongsToCurrentThread());
had_non_speculative_request_ = true;
}
bool was_canceled() const {
DCHECK(origin_loop_->BelongsToCurrentThread());
return callback_.is_null();
}
bool was_completed() const {
DCHECK(origin_loop_->BelongsToCurrentThread());
return completed_attempt_number_ > 0;
}
private:
friend class base::RefCountedThreadSafe<ProcTask>;
~ProcTask() {}
void StartLookupAttempt() {
TRACK_MEMORY_SCOPE("Network");
DCHECK(origin_loop_->BelongsToCurrentThread());
base::TimeTicks start_time = base::TimeTicks::Now();
++attempt_number_;
// Dispatch the lookup attempt to a worker thread.
if (!base::WorkerPool::PostTask(
FROM_HERE,
base::Bind(&ProcTask::DoLookup, this, start_time, attempt_number_),
true)) {
NOTREACHED();
// Since we could be running within Resolve() right now, we can't just
// call OnLookupComplete(). Instead we must wait until Resolve() has
// returned (IO_PENDING).
origin_loop_->PostTask(
FROM_HERE,
base::Bind(&ProcTask::OnLookupComplete, this, AddressList(),
start_time, attempt_number_, ERR_UNEXPECTED, 0));
return;
}
net_log_.AddEvent(
NetLog::TYPE_HOST_RESOLVER_IMPL_ATTEMPT_STARTED,
NetLog::IntegerCallback("attempt_number", attempt_number_));
// If we don't get the results within a given time, RetryIfNotComplete
// will start a new attempt on a different worker thread if none of our
// outstanding attempts have completed yet.
if (attempt_number_ <= params_.max_retry_attempts) {
origin_loop_->PostDelayedTask(
FROM_HERE,
base::Bind(&ProcTask::RetryIfNotComplete, this),
params_.unresponsive_delay);
}
}
// WARNING: This code runs inside a worker pool. The shutdown code cannot
// wait for it to finish, so we must be very careful here about using other
// objects (like MessageLoops, Singletons, etc). During shutdown these objects
// may no longer exist. Multiple DoLookups() could be running in parallel, so
// any state inside of |this| must not mutate .
void DoLookup(const base::TimeTicks& start_time,
const uint32 attempt_number) {
AddressList results;
int os_error = 0;
// Running on the worker thread
int error = params_.resolver_proc->Resolve(key_.hostname,
key_.address_family,
key_.host_resolver_flags,
&results,
&os_error);
origin_loop_->PostTask(
FROM_HERE,
base::Bind(&ProcTask::OnLookupComplete, this, results, start_time,
attempt_number, error, os_error));
}
// Makes next attempt if DoLookup() has not finished (runs on origin thread).
void RetryIfNotComplete() {
DCHECK(origin_loop_->BelongsToCurrentThread());
if (was_completed() || was_canceled())
return;
params_.unresponsive_delay *= params_.retry_factor;
StartLookupAttempt();
}
// Callback for when DoLookup() completes (runs on origin thread).
void OnLookupComplete(const AddressList& results,
const base::TimeTicks& start_time,
const uint32 attempt_number,
int error,
const int os_error) {
DCHECK(origin_loop_->BelongsToCurrentThread());
DCHECK(error || !results.empty());
bool was_retry_attempt = attempt_number > 1;
// Ideally the following code would be part of host_resolver_proc.cc,
// however it isn't safe to call NetworkChangeNotifier from worker threads.
// So we do it here on the IO thread instead.
if (error != OK && NetworkChangeNotifier::IsOffline())
error = ERR_INTERNET_DISCONNECTED;
// If this is the first attempt that is finishing later, then record data
// for the first attempt. Won't contaminate with retry attempt's data.
if (!was_retry_attempt)
RecordPerformanceHistograms(start_time, error, os_error);
RecordAttemptHistograms(start_time, attempt_number, error, os_error);
if (was_canceled())
return;
NetLog::ParametersCallback net_log_callback;
if (error != OK) {
net_log_callback = base::Bind(&NetLogProcTaskFailedCallback,
attempt_number,
error,
os_error);
} else {
net_log_callback = NetLog::IntegerCallback("attempt_number",
attempt_number);
}
net_log_.AddEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_ATTEMPT_FINISHED,
net_log_callback);
if (was_completed())
return;
// Copy the results from the first worker thread that resolves the host.
results_ = results;
completed_attempt_number_ = attempt_number;
completed_attempt_error_ = error;
if (was_retry_attempt) {
// If retry attempt finishes before 1st attempt, then get stats on how
// much time is saved by having spawned an extra attempt.
retry_attempt_finished_time_ = base::TimeTicks::Now();
}
if (error != OK) {
net_log_callback = base::Bind(&NetLogProcTaskFailedCallback,
0, error, os_error);
} else {
net_log_callback = results_.CreateNetLogCallback();
}
net_log_.EndEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_PROC_TASK,
net_log_callback);
callback_.Run(error, results_);
}
void RecordPerformanceHistograms(const base::TimeTicks& start_time,
const int error,
const int os_error) const {
DCHECK(origin_loop_->BelongsToCurrentThread());
enum Category { // Used in HISTOGRAM_ENUMERATION.
RESOLVE_SUCCESS,
RESOLVE_FAIL,
RESOLVE_SPECULATIVE_SUCCESS,
RESOLVE_SPECULATIVE_FAIL,
RESOLVE_MAX, // Bounding value.
};
int category = RESOLVE_MAX; // Illegal value for later DCHECK only.
base::TimeDelta duration = base::TimeTicks::Now() - start_time;
if (error == OK) {
if (had_non_speculative_request_) {
category = RESOLVE_SUCCESS;
DNS_HISTOGRAM("DNS.ResolveSuccess", duration);
} else {
category = RESOLVE_SPECULATIVE_SUCCESS;
DNS_HISTOGRAM("DNS.ResolveSpeculativeSuccess", duration);
}
// Log DNS lookups based on |address_family|. This will help us determine
// if IPv4 or IPv4/6 lookups are faster or slower.
switch(key_.address_family) {
case ADDRESS_FAMILY_IPV4:
DNS_HISTOGRAM("DNS.ResolveSuccess_FAMILY_IPV4", duration);
break;
case ADDRESS_FAMILY_IPV6:
DNS_HISTOGRAM("DNS.ResolveSuccess_FAMILY_IPV6", duration);
break;
case ADDRESS_FAMILY_UNSPECIFIED:
DNS_HISTOGRAM("DNS.ResolveSuccess_FAMILY_UNSPEC", duration);
break;
}
} else {
if (had_non_speculative_request_) {
category = RESOLVE_FAIL;
DNS_HISTOGRAM("DNS.ResolveFail", duration);
} else {
category = RESOLVE_SPECULATIVE_FAIL;
DNS_HISTOGRAM("DNS.ResolveSpeculativeFail", duration);
}
// Log DNS lookups based on |address_family|. This will help us determine
// if IPv4 or IPv4/6 lookups are faster or slower.
switch(key_.address_family) {
case ADDRESS_FAMILY_IPV4:
DNS_HISTOGRAM("DNS.ResolveFail_FAMILY_IPV4", duration);
break;
case ADDRESS_FAMILY_IPV6:
DNS_HISTOGRAM("DNS.ResolveFail_FAMILY_IPV6", duration);
break;
case ADDRESS_FAMILY_UNSPECIFIED:
DNS_HISTOGRAM("DNS.ResolveFail_FAMILY_UNSPEC", duration);
break;
}
#if !defined(OS_STARBOARD)
UMA_HISTOGRAM_CUSTOM_ENUMERATION(kOSErrorsForGetAddrinfoHistogramName,
std::abs(os_error),
GetAllGetAddrinfoOSErrors());
#endif // !defined(OS_STARBOARD)
}
DCHECK_LT(category, static_cast<int>(RESOLVE_MAX)); // Be sure it was set.
UMA_HISTOGRAM_ENUMERATION("DNS.ResolveCategory", category, RESOLVE_MAX);
static const bool show_parallelism_experiment_histograms =
base::FieldTrialList::TrialExists("DnsParallelism");
if (show_parallelism_experiment_histograms) {
UMA_HISTOGRAM_ENUMERATION(
base::FieldTrial::MakeName("DNS.ResolveCategory", "DnsParallelism"),
category, RESOLVE_MAX);
if (RESOLVE_SUCCESS == category) {
DNS_HISTOGRAM(base::FieldTrial::MakeName("DNS.ResolveSuccess",
"DnsParallelism"), duration);
}
}
}
void RecordAttemptHistograms(const base::TimeTicks& start_time,
const uint32 attempt_number,
const int error,
const int os_error) const {
DCHECK(origin_loop_->BelongsToCurrentThread());
bool first_attempt_to_complete =
completed_attempt_number_ == attempt_number;
bool is_first_attempt = (attempt_number == 1);
if (first_attempt_to_complete) {
// If this was first attempt to complete, then record the resolution
// status of the attempt.
if (completed_attempt_error_ == OK) {
UMA_HISTOGRAM_ENUMERATION(
"DNS.AttemptFirstSuccess", attempt_number, 100);
} else {
UMA_HISTOGRAM_ENUMERATION(
"DNS.AttemptFirstFailure", attempt_number, 100);
}
}
if (error == OK)
UMA_HISTOGRAM_ENUMERATION("DNS.AttemptSuccess", attempt_number, 100);
else
UMA_HISTOGRAM_ENUMERATION("DNS.AttemptFailure", attempt_number, 100);
// If first attempt didn't finish before retry attempt, then calculate stats
// on how much time is saved by having spawned an extra attempt.
if (!first_attempt_to_complete && is_first_attempt && !was_canceled()) {
DNS_HISTOGRAM("DNS.AttemptTimeSavedByRetry",
base::TimeTicks::Now() - retry_attempt_finished_time_);
}
if (was_canceled() || !first_attempt_to_complete) {
// Count those attempts which completed after the job was already canceled
// OR after the job was already completed by an earlier attempt (so in
// effect).
UMA_HISTOGRAM_ENUMERATION("DNS.AttemptDiscarded", attempt_number, 100);
// Record if job is canceled.
if (was_canceled())
UMA_HISTOGRAM_ENUMERATION("DNS.AttemptCancelled", attempt_number, 100);
}
base::TimeDelta duration = base::TimeTicks::Now() - start_time;
if (error == OK)
DNS_HISTOGRAM("DNS.AttemptSuccessDuration", duration);
else
DNS_HISTOGRAM("DNS.AttemptFailDuration", duration);
}
// Set on the origin thread, read on the worker thread.
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 ourselves onto the origin thread.
scoped_refptr<base::MessageLoopProxy> origin_loop_;
// 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 attempt_number_;
// The index of the attempt which finished first (or 0 if the job is still in
// progress).
uint32 completed_attempt_number_;
// The result (a net error code) from the first attempt to complete.
int completed_attempt_error_;
// The time when retry attempt was finished.
base::TimeTicks retry_attempt_finished_time_;
// True if a non-speculative request was ever attached to this job
// (regardless of whether or not it was later canceled.
// This boolean is used for histogramming the duration of jobs used to
// service non-speculative requests.
bool had_non_speculative_request_;
AddressList results_;
BoundNetLog net_log_;
DISALLOW_COPY_AND_ASSIGN(ProcTask);
};
//-----------------------------------------------------------------------------
// Wraps a call to TestIPv6Support to be executed on the WorkerPool as it takes
// 40-100ms.
class HostResolverImpl::IPv6ProbeJob {
public:
IPv6ProbeJob(const base::WeakPtr<HostResolverImpl>& resolver, NetLog* net_log)
: resolver_(resolver),
net_log_(BoundNetLog::Make(net_log, NetLog::SOURCE_IPV6_PROBE_JOB)),
result_(false, IPV6_SUPPORT_MAX, OK) {
DCHECK(resolver);
net_log_.BeginEvent(NetLog::TYPE_IPV6_PROBE_RUNNING);
const bool kIsSlow = true;
base::WorkerPool::PostTaskAndReply(
FROM_HERE,
base::Bind(&IPv6ProbeJob::DoProbe, base::Unretained(this)),
base::Bind(&IPv6ProbeJob::OnProbeComplete, base::Owned(this)),
kIsSlow);
}
virtual ~IPv6ProbeJob() {}
private:
// Runs on worker thread.
void DoProbe() {
result_ = TestIPv6Support();
}
void OnProbeComplete() {
net_log_.EndEvent(NetLog::TYPE_IPV6_PROBE_RUNNING,
base::Bind(&IPv6SupportResult::ToNetLogValue,
base::Unretained(&result_)));
if (!resolver_)
return;
resolver_->IPv6ProbeSetDefaultAddressFamily(
result_.ipv6_supported ? ADDRESS_FAMILY_UNSPECIFIED
: ADDRESS_FAMILY_IPV4);
}
// Used/set only on origin thread.
base::WeakPtr<HostResolverImpl> resolver_;
BoundNetLog net_log_;
IPv6SupportResult result_;
DISALLOW_COPY_AND_ASSIGN(IPv6ProbeJob);
};
// Wraps a call to HaveOnlyLoopbackAddresses to be executed on the WorkerPool as
// it takes 40-100ms and should not block initialization.
class HostResolverImpl::LoopbackProbeJob {
public:
explicit LoopbackProbeJob(const base::WeakPtr<HostResolverImpl>& resolver)
: resolver_(resolver),
result_(false) {
DCHECK(resolver);
const bool kIsSlow = true;
base::WorkerPool::PostTaskAndReply(
FROM_HERE,
base::Bind(&LoopbackProbeJob::DoProbe, base::Unretained(this)),
base::Bind(&LoopbackProbeJob::OnProbeComplete, base::Owned(this)),
kIsSlow);
}
virtual ~LoopbackProbeJob() {}
private:
// Runs on worker thread.
void DoProbe() {
result_ = HaveOnlyLoopbackAddresses();
}
void OnProbeComplete() {
if (!resolver_)
return;
resolver_->SetHaveOnlyLoopbackAddresses(result_);
}
// Used/set only on origin thread.
base::WeakPtr<HostResolverImpl> resolver_;
bool result_;
DISALLOW_COPY_AND_ASSIGN(LoopbackProbeJob);
};
//-----------------------------------------------------------------------------
// Resolves the hostname using DnsTransaction.
// TODO(szym): This could be moved to separate source file as well.
class HostResolverImpl::DnsTask : public base::SupportsWeakPtr<DnsTask> {
public:
typedef base::Callback<void(int net_error,
const AddressList& addr_list,
base::TimeDelta ttl)> Callback;
DnsTask(DnsClient* client,
const Key& key,
const Callback& callback,
const BoundNetLog& job_net_log)
: client_(client),
family_(key.address_family),
callback_(callback),
net_log_(job_net_log) {
DCHECK(client);
DCHECK(!callback.is_null());
// If unspecified, do IPv4 first, because suffix search will be faster.
uint16 qtype = (family_ == ADDRESS_FAMILY_IPV6) ?
dns_protocol::kTypeAAAA :
dns_protocol::kTypeA;
transaction_ = client_->GetTransactionFactory()->CreateTransaction(
key.hostname,
qtype,
base::Bind(&DnsTask::OnTransactionComplete, base::Unretained(this),
true /* first_query */, base::TimeTicks::Now()),
net_log_);
}
int Start() {
net_log_.BeginEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_DNS_TASK);
return transaction_->Start();
}
private:
void OnTransactionComplete(bool first_query,
const base::TimeTicks& start_time,
DnsTransaction* transaction,
int net_error,
const DnsResponse* response) {
DCHECK(transaction);
// Run |callback_| last since the owning Job will then delete this DnsTask.
if (net_error != OK) {
DNS_HISTOGRAM("AsyncDNS.TransactionFailure",
base::TimeTicks::Now() - start_time);
OnFailure(net_error, DnsResponse::DNS_PARSE_OK);
return;
}
CHECK(response);
DNS_HISTOGRAM("AsyncDNS.TransactionSuccess",
base::TimeTicks::Now() - start_time);
AddressList addr_list;
base::TimeDelta ttl;
DnsResponse::Result result = response->ParseToAddressList(&addr_list, &ttl);
UMA_HISTOGRAM_ENUMERATION("AsyncDNS.ParseToAddressList",
result,
DnsResponse::DNS_PARSE_RESULT_MAX);
if (result != DnsResponse::DNS_PARSE_OK) {
// Fail even if the other query succeeds.
OnFailure(ERR_DNS_MALFORMED_RESPONSE, result);
return;
}
bool needs_sort = false;
if (first_query) {
DCHECK(client_->GetConfig()) <<
"Transaction should have been aborted when config changed!";
if (family_ == ADDRESS_FAMILY_IPV6) {
needs_sort = (addr_list.size() > 1);
} else if (family_ == ADDRESS_FAMILY_UNSPECIFIED) {
first_addr_list_ = addr_list;
first_ttl_ = ttl;
// Use fully-qualified domain name to avoid search.
transaction_ = client_->GetTransactionFactory()->CreateTransaction(
response->GetDottedName() + ".",
dns_protocol::kTypeAAAA,
base::Bind(&DnsTask::OnTransactionComplete, base::Unretained(this),
false /* first_query */, base::TimeTicks::Now()),
net_log_);
net_error = transaction_->Start();
if (net_error != ERR_IO_PENDING)
OnFailure(net_error, DnsResponse::DNS_PARSE_OK);
return;
}
} else {
DCHECK_EQ(ADDRESS_FAMILY_UNSPECIFIED, family_);
bool has_ipv6_addresses = !addr_list.empty();
if (!first_addr_list_.empty()) {
ttl = std::min(ttl, first_ttl_);
// Place IPv4 addresses after IPv6.
addr_list.insert(addr_list.end(), first_addr_list_.begin(),
first_addr_list_.end());
}
needs_sort = (has_ipv6_addresses && addr_list.size() > 1);
}
if (addr_list.empty()) {
// TODO(szym): Don't fallback to ProcTask in this case.
OnFailure(ERR_NAME_NOT_RESOLVED, DnsResponse::DNS_PARSE_OK);
return;
}
if (needs_sort) {
// Sort could complete synchronously.
client_->GetAddressSorter()->Sort(
addr_list,
base::Bind(&DnsTask::OnSortComplete,
AsWeakPtr(),
base::TimeTicks::Now(),
ttl));
} else {
OnSuccess(addr_list, ttl);
}
}
void OnSortComplete(base::TimeTicks start_time,
base::TimeDelta ttl,
bool success,
const AddressList& addr_list) {
if (!success) {
DNS_HISTOGRAM("AsyncDNS.SortFailure",
base::TimeTicks::Now() - start_time);
OnFailure(ERR_DNS_SORT_ERROR, DnsResponse::DNS_PARSE_OK);
return;
}
DNS_HISTOGRAM("AsyncDNS.SortSuccess",
base::TimeTicks::Now() - start_time);
// AddressSorter prunes unusable destinations.
if (addr_list.empty()) {
LOG(WARNING) << "Address list empty after RFC3484 sort";
OnFailure(ERR_NAME_NOT_RESOLVED, DnsResponse::DNS_PARSE_OK);
return;
}
OnSuccess(addr_list, ttl);
}
void OnFailure(int net_error, DnsResponse::Result result) {
DCHECK_NE(OK, net_error);
net_log_.EndEvent(
NetLog::TYPE_HOST_RESOLVER_IMPL_DNS_TASK,
base::Bind(&NetLogDnsTaskFailedCallback, net_error, result));
callback_.Run(net_error, AddressList(), base::TimeDelta());
}
void OnSuccess(const AddressList& addr_list, base::TimeDelta ttl) {
net_log_.EndEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_DNS_TASK,
addr_list.CreateNetLogCallback());
callback_.Run(OK, addr_list, ttl);
}
DnsClient* client_;
AddressFamily family_;
// The listener to the results of this DnsTask.
Callback callback_;
const BoundNetLog net_log_;
scoped_ptr<DnsTransaction> transaction_;
// Results from the first transaction. Used only if |family_| is unspecified.
AddressList first_addr_list_;
base::TimeDelta first_ttl_;
DISALLOW_COPY_AND_ASSIGN(DnsTask);
};
//-----------------------------------------------------------------------------
// Aggregates all Requests for the same Key. Dispatched via PriorityDispatch.
class HostResolverImpl::Job : public PrioritizedDispatcher::Job {
public:
// Creates new job for |key| where |request_net_log| is bound to the
// request that spawned it.
Job(const base::WeakPtr<HostResolverImpl>& resolver,
const Key& key,
RequestPriority priority,
const BoundNetLog& request_net_log)
: resolver_(resolver),
key_(key),
priority_tracker_(priority),
had_non_speculative_request_(false),
had_dns_config_(false),
dns_task_error_(OK),
creation_time_(base::TimeTicks::Now()),
priority_change_time_(creation_time_),
net_log_(BoundNetLog::Make(request_net_log.net_log(),
NetLog::SOURCE_HOST_RESOLVER_IMPL_JOB)) {
request_net_log.AddEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_CREATE_JOB);
net_log_.BeginEvent(
NetLog::TYPE_HOST_RESOLVER_IMPL_JOB,
base::Bind(&NetLogJobCreationCallback,
request_net_log.source(),
&key_.hostname));
}
virtual ~Job() {
if (is_running()) {
// |resolver_| was destroyed with this Job still in flight.
// Clean-up, record in the log, but don't run any callbacks.
if (is_proc_running()) {
proc_task_->Cancel();
proc_task_ = NULL;
}
// Clean up now for nice NetLog.
dns_task_.reset(NULL);
net_log_.EndEventWithNetErrorCode(NetLog::TYPE_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(NetLog::TYPE_CANCELLED);
net_log_.EndEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_JOB);
}
// else CompleteRequests logged EndEvent.
// Log any remaining Requests as cancelled.
for (RequestsList::const_iterator it = requests_.begin();
it != requests_.end(); ++it) {
Request* req = *it;
if (req->was_canceled())
continue;
DCHECK_EQ(this, req->job());
LogCancelRequest(req->source_net_log(), req->request_net_log(),
req->info());
}
}
// Add this job to the dispatcher.
void Schedule() {
handle_ = resolver_->dispatcher_.Add(this, priority());
}
void AddRequest(scoped_ptr<Request> req) {
DCHECK_EQ(key_.hostname, req->info().hostname());
req->set_job(this);
priority_tracker_.Add(req->info().priority());
req->request_net_log().AddEvent(
NetLog::TYPE_HOST_RESOLVER_IMPL_JOB_ATTACH,
net_log_.source().ToEventParametersCallback());
net_log_.AddEvent(
NetLog::TYPE_HOST_RESOLVER_IMPL_JOB_REQUEST_ATTACH,
base::Bind(&NetLogJobAttachCallback,
req->request_net_log().source(),
priority()));
// TODO(szym): Check if this is still needed.
if (!req->info().is_speculative()) {
had_non_speculative_request_ = true;
if (proc_task_)
proc_task_->set_had_non_speculative_request();
}
requests_.push_back(req.release());
UpdatePriority();
}
// Marks |req| as cancelled. If it was the last active Request, also finishes
// this Job, marking it as cancelled, and deletes it.
void CancelRequest(Request* req) {
DCHECK_EQ(key_.hostname, req->info().hostname());
DCHECK(!req->was_canceled());
// Don't remove it from |requests_| just mark it canceled.
req->MarkAsCanceled();
LogCancelRequest(req->source_net_log(), req->request_net_log(),
req->info());
priority_tracker_.Remove(req->info().priority());
net_log_.AddEvent(
NetLog::TYPE_HOST_RESOLVER_IMPL_JOB_REQUEST_DETACH,
base::Bind(&NetLogJobAttachCallback,
req->request_net_log().source(),
priority()));
if (num_active_requests() > 0) {
UpdatePriority();
} 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(OK /* cancelled */);
}
}
// Called from AbortAllInProgressJobs. Completes all requests and destroys
// the job. This currently assumes the abort is due to a network change.
void Abort() {
DCHECK(is_running());
CompleteRequestsWithError(ERR_NETWORK_CHANGED);
}
// If DnsTask present, abort it and fall back to ProcTask.
void AbortDnsTask() {
if (dns_task_) {
dns_task_.reset();
dns_task_error_ = OK;
StartProcTask();
}
}
// Called by HostResolverImpl when this job is evicted due to queue overflow.
// Completes all requests and destroys the job.
void OnEvicted() {
DCHECK(!is_running());
DCHECK(is_queued());
handle_.Reset();
net_log_.AddEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_JOB_EVICTED);
// This signals to CompleteRequests that this job never ran.
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);
AddressList addr_list;
if (resolver_->ServeFromHosts(key(),
requests_.front()->info(),
&addr_list)) {
// This will destroy the Job.
CompleteRequests(
HostCache::Entry(OK, MakeAddressListForRequest(addr_list)),
base::TimeDelta());
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_proc_running();
}
private:
void UpdatePriority() {
if (is_queued()) {
if (priority() != static_cast<RequestPriority>(handle_.priority()))
priority_change_time_ = base::TimeTicks::Now();
handle_ = resolver_->dispatcher_.ChangePriority(handle_, priority());
}
}
AddressList MakeAddressListForRequest(const AddressList& list) const {
if (requests_.empty())
return list;
return AddressList::CopyWithPort(list, requests_.front()->info().port());
}
// PriorityDispatch::Job:
virtual void Start() override {
DCHECK(!is_running());
handle_.Reset();
net_log_.AddEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_JOB_STARTED);
had_dns_config_ = resolver_->HaveDnsConfig();
base::TimeTicks now = base::TimeTicks::Now();
base::TimeDelta queue_time = now - creation_time_;
base::TimeDelta queue_time_after_change = now - priority_change_time_;
if (had_dns_config_) {
DNS_HISTOGRAM_BY_PRIORITY("AsyncDNS.JobQueueTime", priority(),
queue_time);
DNS_HISTOGRAM_BY_PRIORITY("AsyncDNS.JobQueueTimeAfterChange", priority(),
queue_time_after_change);
} else {
DNS_HISTOGRAM_BY_PRIORITY("DNS.JobQueueTime", priority(), queue_time);
DNS_HISTOGRAM_BY_PRIORITY("DNS.JobQueueTimeAfterChange", priority(),
queue_time_after_change);
}
// Caution: Job::Start must not complete synchronously.
if (had_dns_config_ && !ResemblesMulticastDNSName(key_.hostname)) {
StartDnsTask();
} else {
StartProcTask();
}
}
// TODO(szym): Since DnsTransaction does not consume threads, we can increase
// the limits on |dispatcher_|. But in order to keep the number of WorkerPool
// threads low, we will need to use an "inner" PrioritizedDispatcher with
// tighter limits.
void StartProcTask() {
DCHECK(!is_dns_running());
proc_task_ = new ProcTask(
key_,
resolver_->proc_params_,
base::Bind(&Job::OnProcTaskComplete, base::Unretained(this),
base::TimeTicks::Now()),
net_log_);
if (had_non_speculative_request_)
proc_task_->set_had_non_speculative_request();
// 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) {
base::TimeDelta duration = base::TimeTicks::Now() - start_time;
if (net_error == OK) {
DNS_HISTOGRAM("AsyncDNS.FallbackSuccess", duration);
if ((dns_task_error_ == ERR_NAME_NOT_RESOLVED) &&
ResemblesNetBIOSName(key_.hostname)) {
UmaAsyncDnsResolveStatus(RESOLVE_STATUS_SUSPECT_NETBIOS);
} else {
UmaAsyncDnsResolveStatus(RESOLVE_STATUS_PROC_SUCCESS);
}
UMA_HISTOGRAM_CUSTOM_ENUMERATION("AsyncDNS.ResolveError",
std::abs(dns_task_error_),
GetAllErrorCodesForUma());
resolver_->OnDnsTaskResolve(dns_task_error_);
} else {
DNS_HISTOGRAM("AsyncDNS.FallbackFail", duration);
UmaAsyncDnsResolveStatus(RESOLVE_STATUS_FAIL);
}
}
base::TimeDelta ttl =
base::TimeDelta::FromSeconds(kNegativeCacheEntryTTLSeconds);
if (net_error == OK)
ttl = base::TimeDelta::FromSeconds(kCacheEntryTTLSeconds);
// Don't store the |ttl| in cache since it's not obtained from the server.
CompleteRequests(
HostCache::Entry(net_error, MakeAddressListForRequest(addr_list)),
ttl);
}
void StartDnsTask() {
DCHECK(resolver_->HaveDnsConfig());
dns_task_.reset(new DnsTask(
resolver_->dns_client_.get(),
key_,
base::Bind(&Job::OnDnsTaskComplete, base::Unretained(this),
base::TimeTicks::Now()),
net_log_));
int rv = dns_task_->Start();
if (rv != ERR_IO_PENDING) {
DCHECK_NE(OK, rv);
dns_task_error_ = rv;
dns_task_.reset();
StartProcTask();
}
}
// Called by DnsTask when it completes.
void OnDnsTaskComplete(base::TimeTicks start_time,
int net_error,
const AddressList& addr_list,
base::TimeDelta ttl) {
DCHECK(is_dns_running());
base::TimeDelta duration = base::TimeTicks::Now() - start_time;
if (net_error != OK) {
DNS_HISTOGRAM("AsyncDNS.ResolveFail", duration);
dns_task_error_ = net_error;
dns_task_.reset();
// 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.
StartProcTask();
return;
}
DNS_HISTOGRAM("AsyncDNS.ResolveSuccess", duration);
UmaAsyncDnsResolveStatus(RESOLVE_STATUS_DNS_SUCCESS);
RecordTTL(ttl);
resolver_->OnDnsTaskResolve(OK);
base::TimeDelta bounded_ttl =
std::max(ttl, base::TimeDelta::FromSeconds(kMinimumTTLSeconds));
CompleteRequests(
HostCache::Entry(net_error, MakeAddressListForRequest(addr_list), ttl),
bounded_ttl);
}
// Performs Job's last rites. Completes all Requests. Deletes this.
void CompleteRequests(const HostCache::Entry& entry,
base::TimeDelta ttl) {
CHECK(resolver_);
// 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, the job deletes itself when CompleteRequests
// is done.
scoped_ptr<Job> self_deleter(this);
resolver_->RemoveJob(this);
if (is_running()) {
DCHECK(!is_queued());
if (is_proc_running()) {
proc_task_->Cancel();
proc_task_ = NULL;
}
dns_task_.reset();
// 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(NetLog::TYPE_CANCELLED);
net_log_.EndEventWithNetErrorCode(NetLog::TYPE_HOST_RESOLVER_IMPL_JOB,
OK);
return;
}
net_log_.EndEventWithNetErrorCode(NetLog::TYPE_HOST_RESOLVER_IMPL_JOB,
entry.error);
DCHECK(!requests_.empty());
if (entry.error == OK) {
// Record this histogram here, when we know the system has a valid DNS
// configuration.
UMA_HISTOGRAM_BOOLEAN("AsyncDNS.HaveDnsConfig",
resolver_->received_dns_config_);
}
bool did_complete = (entry.error != ERR_NETWORK_CHANGED) &&
(entry.error != ERR_HOST_RESOLVER_QUEUE_TOO_LARGE);
if (did_complete)
resolver_->CacheResult(key_, entry, ttl);
// Complete all of the requests that were attached to the job.
for (RequestsList::const_iterator it = requests_.begin();
it != requests_.end(); ++it) {
Request* req = *it;
if (req->was_canceled())
continue;
DCHECK_EQ(this, req->job());
// Update the net log and notify registered observers.
LogFinishRequest(req->source_net_log(), req->request_net_log(),
req->info(), entry.error);
if (did_complete) {
// Record effective total time from creation to completion.
RecordTotalTime(had_dns_config_, req->info().is_speculative(),
base::TimeTicks::Now() - req->request_time());
}
req->OnComplete(entry.error, entry.addrlist);
// 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_)
return;
}
}
// Convenience wrapper for CompleteRequests in case of failure.
void CompleteRequestsWithError(int net_error) {
CompleteRequests(HostCache::Entry(net_error, AddressList()),
base::TimeDelta());
}
RequestPriority priority() const {
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_.get() != NULL;
}
bool is_proc_running() const {
return proc_task_.get() != NULL;
}
base::WeakPtr<HostResolverImpl> resolver_;
Key key_;
// Tracks the highest priority across |requests_|.
PriorityTracker priority_tracker_;
bool had_non_speculative_request_;
// Distinguishes measurements taken while DnsClient was fully configured.
bool had_dns_config_;
// Result of DnsTask.
int dns_task_error_;
const base::TimeTicks creation_time_;
base::TimeTicks priority_change_time_;
BoundNetLog net_log_;
// Resolves the host using a HostResolverProc.
scoped_refptr<ProcTask> proc_task_;
// Resolves the host using a DnsTransaction.
scoped_ptr<DnsTask> dns_task_;
// All Requests waiting for the result of this Job. Some can be canceled.
RequestsList requests_;
// A handle used in |HostResolverImpl::dispatcher_|.
PrioritizedDispatcher::Handle handle_;
};
//-----------------------------------------------------------------------------
HostResolverImpl::ProcTaskParams::ProcTaskParams(
HostResolverProc* resolver_proc,
size_t max_retry_attempts)
: resolver_proc(resolver_proc),
max_retry_attempts(max_retry_attempts),
unresponsive_delay(base::TimeDelta::FromMilliseconds(6000)),
retry_factor(2) {
}
HostResolverImpl::ProcTaskParams::~ProcTaskParams() {}
HostResolverImpl::HostResolverImpl(
scoped_ptr<HostCache> cache,
const PrioritizedDispatcher::Limits& job_limits,
const ProcTaskParams& proc_params,
NetLog* net_log)
: cache_(cache.Pass()),
dispatcher_(job_limits),
max_queued_jobs_(job_limits.total_jobs * 100u),
proc_params_(proc_params),
default_address_family_(ADDRESS_FAMILY_UNSPECIFIED),
weak_ptr_factory_(this),
probe_weak_ptr_factory_(this),
received_dns_config_(false),
num_dns_failures_(0),
ipv6_probe_monitoring_(false),
additional_resolver_flags_(0),
net_log_(net_log) {
DCHECK_GE(dispatcher_.num_priorities(), static_cast<size_t>(NUM_PRIORITIES));
// Maximum of 4 retry attempts for host resolution.
static const size_t kDefaultMaxRetryAttempts = 4u;
if (proc_params_.max_retry_attempts == HostResolver::kDefaultRetryAttempts)
proc_params_.max_retry_attempts = kDefaultMaxRetryAttempts;
#if defined(OS_WIN)
EnsureWinsockInit();
#endif
#if defined(OS_POSIX) && !defined(OS_MACOSX)
new LoopbackProbeJob(weak_ptr_factory_.GetWeakPtr());
#endif
NetworkChangeNotifier::AddIPAddressObserver(this);
NetworkChangeNotifier::AddDNSObserver(this);
#if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_OPENBSD) && \
!defined(OS_ANDROID) && !defined(__LB_SHELL__)
EnsureDnsReloaderInit();
#endif
// TODO(szym): Remove when received_dns_config_ is removed, once
// http://crbug.com/137914 is resolved.
{
DnsConfig dns_config;
NetworkChangeNotifier::GetDnsConfig(&dns_config);
received_dns_config_ = dns_config.IsValid();
}
}
HostResolverImpl::~HostResolverImpl() {
// This will also cancel all outstanding requests.
STLDeleteValues(&jobs_);
NetworkChangeNotifier::RemoveIPAddressObserver(this);
NetworkChangeNotifier::RemoveDNSObserver(this);
}
void HostResolverImpl::SetMaxQueuedJobs(size_t value) {
DCHECK_EQ(0u, dispatcher_.num_queued_jobs());
DCHECK_GT(value, 0u);
max_queued_jobs_ = value;
}
int HostResolverImpl::Resolve(const RequestInfo& info,
AddressList* addresses,
const CompletionCallback& callback,
RequestHandle* out_req,
const BoundNetLog& source_net_log) {
DCHECK(addresses);
DCHECK(CalledOnValidThread());
DCHECK_EQ(false, callback.is_null());
// Make a log item for the request.
BoundNetLog request_net_log = BoundNetLog::Make(net_log_,
NetLog::SOURCE_HOST_RESOLVER_IMPL_REQUEST);
LogStartRequest(source_net_log, request_net_log, info);
// Build a key that identifies the request in the cache and in the
// outstanding jobs map.
Key key = GetEffectiveKeyForRequest(info);
int rv = ResolveHelper(key, info, addresses, request_net_log);
if (rv != ERR_DNS_CACHE_MISS) {
LogFinishRequest(source_net_log, request_net_log, info, rv);
RecordTotalTime(HaveDnsConfig(), info.is_speculative(), base::TimeDelta());
return rv;
}
// Next we need to attach our request to a "job". This job is responsible for
// calling "getaddrinfo(hostname)" on a worker thread.
JobMap::iterator jobit = jobs_.find(key);
Job* job;
if (jobit == jobs_.end()) {
// If we couldn't find the desired address family, check to see if the
// other family is in the cache or another job, which indicates waste,
// and we should fix crbug.com/139811.
{
bool ipv4 = key.address_family == ADDRESS_FAMILY_IPV4;
Key other_family_key = key;
other_family_key.address_family = ipv4 ?
ADDRESS_FAMILY_UNSPECIFIED : ADDRESS_FAMILY_IPV4;
bool found_other_family_cache = false;
bool found_other_family_job = false;
if (default_address_family_ == ADDRESS_FAMILY_UNSPECIFIED) {
found_other_family_cache = cache_.get() &&
cache_->Lookup(other_family_key, base::TimeTicks::Now()) != NULL;
if (!found_other_family_cache)
found_other_family_job = jobs_.count(other_family_key) > 0;
}
enum { // Used in UMA_HISTOGRAM_ENUMERATION.
AF_WASTE_IPV4_ONLY,
AF_WASTE_CACHE_IPV4,
AF_WASTE_CACHE_UNSPEC,
AF_WASTE_JOB_IPV4,
AF_WASTE_JOB_UNSPEC,
AF_WASTE_NONE_IPV4,
AF_WASTE_NONE_UNSPEC,
AF_WASTE_MAX, // Bounding value.
} category = AF_WASTE_MAX;
if (default_address_family_ != ADDRESS_FAMILY_UNSPECIFIED) {
category = AF_WASTE_IPV4_ONLY;
} else if (found_other_family_cache) {
category = ipv4 ? AF_WASTE_CACHE_IPV4 : AF_WASTE_CACHE_UNSPEC;
} else if (found_other_family_job) {
category = ipv4 ? AF_WASTE_JOB_IPV4 : AF_WASTE_JOB_UNSPEC;
} else {
category = ipv4 ? AF_WASTE_NONE_IPV4 : AF_WASTE_NONE_UNSPEC;
}
UMA_HISTOGRAM_ENUMERATION("DNS.ResolveUnspecWaste", category,
AF_WASTE_MAX);
}
job = new Job(weak_ptr_factory_.GetWeakPtr(), key, info.priority(),
request_net_log);
job->Schedule();
// Check for queue overflow.
if (dispatcher_.num_queued_jobs() > max_queued_jobs_) {
Job* evicted = static_cast<Job*>(dispatcher_.EvictOldestLowest());
DCHECK(evicted);
evicted->OnEvicted(); // Deletes |evicted|.
if (evicted == job) {
rv = ERR_HOST_RESOLVER_QUEUE_TOO_LARGE;
LogFinishRequest(source_net_log, request_net_log, info, rv);
return rv;
}
}
jobs_.insert(jobit, std::make_pair(key, job));
} else {
job = jobit->second;
}
// Can't complete synchronously. Create and attach request.
scoped_ptr<Request> req(new Request(source_net_log,
request_net_log,
info,
callback,
addresses));
if (out_req)
*out_req = reinterpret_cast<RequestHandle>(req.get());
job->AddRequest(req.Pass());
// Completion happens during Job::CompleteRequests().
return ERR_IO_PENDING;
}
int HostResolverImpl::ResolveHelper(const Key& key,
const RequestInfo& info,
AddressList* addresses,
const BoundNetLog& request_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 (info.hostname().empty() || info.hostname().size() > kMaxHostLength)
return ERR_NAME_NOT_RESOLVED;
int net_error = ERR_UNEXPECTED;
if (ResolveAsIP(key, info, &net_error, addresses))
return net_error;
if (ServeFromCache(key, info, &net_error, addresses)) {
request_net_log.AddEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_CACHE_HIT);
return net_error;
}
// TODO(szym): Do not do this if nsswitch.conf instructs not to.
// http://crbug.com/117655
if (ServeFromHosts(key, info, addresses)) {
request_net_log.AddEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_HOSTS_HIT);
return OK;
}
return ERR_DNS_CACHE_MISS;
}
int HostResolverImpl::ResolveFromCache(const RequestInfo& info,
AddressList* addresses,
const BoundNetLog& source_net_log) {
DCHECK(CalledOnValidThread());
DCHECK(addresses);
// Make a log item for the request.
BoundNetLog request_net_log = BoundNetLog::Make(net_log_,
NetLog::SOURCE_HOST_RESOLVER_IMPL_REQUEST);
// Update the net log and notify registered observers.
LogStartRequest(source_net_log, request_net_log, info);
Key key = GetEffectiveKeyForRequest(info);
int rv = ResolveHelper(key, info, addresses, request_net_log);
LogFinishRequest(source_net_log, request_net_log, info, rv);
return rv;
}
void HostResolverImpl::CancelRequest(RequestHandle req_handle) {
DCHECK(CalledOnValidThread());
Request* req = reinterpret_cast<Request*>(req_handle);
DCHECK(req);
Job* job = req->job();
DCHECK(job);
job->CancelRequest(req);
}
void HostResolverImpl::SetDefaultAddressFamily(AddressFamily address_family) {
DCHECK(CalledOnValidThread());
default_address_family_ = address_family;
ipv6_probe_monitoring_ = false;
}
AddressFamily HostResolverImpl::GetDefaultAddressFamily() const {
return default_address_family_;
}
void HostResolverImpl::ProbeIPv6Support() {
DCHECK(CalledOnValidThread());
DCHECK(!ipv6_probe_monitoring_);
ipv6_probe_monitoring_ = true;
OnIPAddressChanged();
}
void HostResolverImpl::SetDnsClientEnabled(bool enabled) {
DCHECK(CalledOnValidThread());
#if defined(ENABLE_BUILT_IN_DNS)
if (enabled && !dns_client_) {
SetDnsClient(DnsClient::CreateClient(net_log_));
} else if (!enabled && dns_client_) {
SetDnsClient(scoped_ptr<DnsClient>());
}
#endif
}
HostCache* HostResolverImpl::GetHostCache() {
return cache_.get();
}
base::Value* HostResolverImpl::GetDnsConfigAsValue() const {
// Check if async DNS is disabled.
if (!dns_client_.get())
return NULL;
// Check if async DNS is enabled, but we currently have no configuration
// for it.
const DnsConfig* dns_config = dns_client_->GetConfig();
if (dns_config == NULL)
return new DictionaryValue();
return dns_config->ToValue();
}
bool HostResolverImpl::ResolveAsIP(const Key& key,
const RequestInfo& info,
int* net_error,
AddressList* addresses) {
DCHECK(addresses);
DCHECK(net_error);
IPAddressNumber ip_number;
if (!ParseIPLiteralToNumber(key.hostname, &ip_number))
return false;
DCHECK_EQ(key.host_resolver_flags &
~(HOST_RESOLVER_CANONNAME | HOST_RESOLVER_LOOPBACK_ONLY |
HOST_RESOLVER_DEFAULT_FAMILY_SET_DUE_TO_NO_IPV6),
0) << " Unhandled flag";
bool ipv6_disabled = (default_address_family_ == ADDRESS_FAMILY_IPV4) &&
!ipv6_probe_monitoring_;
*net_error = OK;
if ((ip_number.size() == kIPv6AddressSize) && ipv6_disabled) {
*net_error = ERR_NAME_NOT_RESOLVED;
} else {
*addresses = AddressList::CreateFromIPAddress(ip_number, info.port());
if (key.host_resolver_flags & HOST_RESOLVER_CANONNAME)
addresses->SetDefaultCanonicalName();
}
return true;
}
bool HostResolverImpl::ServeFromCache(const Key& key,
const RequestInfo& info,
int* net_error,
AddressList* addresses) {
DCHECK(addresses);
DCHECK(net_error);
if (!info.allow_cached_response() || !cache_.get())
return false;
const HostCache::Entry* cache_entry = cache_->Lookup(
key, base::TimeTicks::Now());
if (!cache_entry)
return false;
*net_error = cache_entry->error;
if (*net_error == OK) {
if (cache_entry->has_ttl())
RecordTTL(cache_entry->ttl);
*addresses = EnsurePortOnAddressList(cache_entry->addrlist, info.port());
}
return true;
}
bool HostResolverImpl::ServeFromHosts(const Key& key,
const RequestInfo& info,
AddressList* addresses) {
DCHECK(addresses);
if (!HaveDnsConfig())
return false;
// HOSTS lookups are case-insensitive.
std::string hostname = StringToLowerASCII(key.hostname);
// 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.
// TODO(szym) http://crbug.com/117850
const DnsHosts& hosts = dns_client_->GetConfig()->hosts;
DnsHosts::const_iterator it = hosts.find(
DnsHostsKey(hostname,
key.address_family == ADDRESS_FAMILY_UNSPECIFIED ?
ADDRESS_FAMILY_IPV4 : key.address_family));
if (it == hosts.end()) {
if (key.address_family != ADDRESS_FAMILY_UNSPECIFIED)
return false;
it = hosts.find(DnsHostsKey(hostname, ADDRESS_FAMILY_IPV6));
if (it == hosts.end())
return false;
}
*addresses = AddressList::CreateFromIPAddress(it->second, info.port());
return true;
}
void HostResolverImpl::CacheResult(const Key& key,
const HostCache::Entry& entry,
base::TimeDelta ttl) {
if (cache_.get())
cache_->Set(key, entry, base::TimeTicks::Now(), ttl);
}
void HostResolverImpl::RemoveJob(Job* job) {
DCHECK(job);
JobMap::iterator it = jobs_.find(job->key());
if (it != jobs_.end() && it->second == job)
jobs_.erase(it);
}
void HostResolverImpl::IPv6ProbeSetDefaultAddressFamily(
AddressFamily address_family) {
DCHECK(address_family == ADDRESS_FAMILY_UNSPECIFIED ||
address_family == ADDRESS_FAMILY_IPV4);
if (!ipv6_probe_monitoring_)
return;
if (default_address_family_ != address_family) {
VLOG(1) << "IPv6Probe forced AddressFamily setting to "
<< ((address_family == ADDRESS_FAMILY_UNSPECIFIED) ?
"ADDRESS_FAMILY_UNSPECIFIED" : "ADDRESS_FAMILY_IPV4");
}
default_address_family_ = address_family;
}
void HostResolverImpl::SetHaveOnlyLoopbackAddresses(bool result) {
if (result) {
additional_resolver_flags_ |= HOST_RESOLVER_LOOPBACK_ONLY;
} else {
additional_resolver_flags_ &= ~HOST_RESOLVER_LOOPBACK_ONLY;
}
}
HostResolverImpl::Key HostResolverImpl::GetEffectiveKeyForRequest(
const RequestInfo& info) const {
HostResolverFlags effective_flags =
info.host_resolver_flags() | additional_resolver_flags_;
AddressFamily effective_address_family = info.address_family();
if (effective_address_family == ADDRESS_FAMILY_UNSPECIFIED &&
default_address_family_ != ADDRESS_FAMILY_UNSPECIFIED) {
effective_address_family = default_address_family_;
if (ipv6_probe_monitoring_)
effective_flags |= HOST_RESOLVER_DEFAULT_FAMILY_SET_DUE_TO_NO_IPV6;
}
return Key(info.hostname(), effective_address_family, effective_flags);
}
void HostResolverImpl::AbortAllInProgressJobs() {
// In Abort, a Request callback could spawn new Jobs with matching keys, so
// first collect and remove all running jobs from |jobs_|.
ScopedVector<Job> jobs_to_abort;
for (JobMap::iterator it = jobs_.begin(); it != jobs_.end(); ) {
Job* job = it->second;
if (job->is_running()) {
jobs_to_abort.push_back(job);
jobs_.erase(it++);
} else {
DCHECK(job->is_queued());
++it;
}
}
// Check if no dispatcher slots leaked out.
DCHECK_EQ(dispatcher_.num_running_jobs(), jobs_to_abort.size());
// Life check to bail once |this| is deleted.
base::WeakPtr<HostResolverImpl> self = weak_ptr_factory_.GetWeakPtr();
// Then Abort them.
for (size_t i = 0; self && i < jobs_to_abort.size(); ++i) {
jobs_to_abort[i]->Abort();
jobs_to_abort[i] = NULL;
}
}
void HostResolverImpl::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<HostResolverImpl> self = weak_ptr_factory_.GetWeakPtr();
for (JobMap::iterator it = jobs_.begin(); self && it != jobs_.end(); ) {
Job* job = it->second;
++it;
// This could remove |job| from |jobs_|, but iterator will remain valid.
job->ServeFromHosts();
}
}
void HostResolverImpl::OnIPAddressChanged() {
// Abandon all ProbeJobs.
probe_weak_ptr_factory_.InvalidateWeakPtrs();
if (cache_.get())
cache_->clear();
if (ipv6_probe_monitoring_)
new IPv6ProbeJob(probe_weak_ptr_factory_.GetWeakPtr(), net_log_);
#if defined(OS_POSIX) && !defined(OS_MACOSX)
new LoopbackProbeJob(probe_weak_ptr_factory_.GetWeakPtr());
#endif
AbortAllInProgressJobs();
// |this| may be deleted inside AbortAllInProgressJobs().
}
void HostResolverImpl::OnDNSChanged() {
DnsConfig dns_config;
NetworkChangeNotifier::GetDnsConfig(&dns_config);
if (net_log_) {
net_log_->AddGlobalEntry(
NetLog::TYPE_DNS_CONFIG_CHANGED,
base::Bind(&NetLogDnsConfigCallback, &dns_config));
}
// TODO(szym): Remove once http://crbug.com/137914 is resolved.
received_dns_config_ = dns_config.IsValid();
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()) {
dns_client_->SetConfig(dns_config);
if (dns_config.IsValid())
UMA_HISTOGRAM_BOOLEAN("AsyncDNS.DnsClientEnabled", true);
}
// If the DNS server has changed, existing cached info could be wrong so we
// have to drop 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_->clear();
// Life check to bail once |this| is deleted.
base::WeakPtr<HostResolverImpl> 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)
TryServingAllJobsFromHosts();
}
bool HostResolverImpl::HaveDnsConfig() const {
return (dns_client_.get() != NULL) && (dns_client_->GetConfig() != NULL);
}
void HostResolverImpl::OnDnsTaskResolve(int net_error) {
DCHECK(dns_client_);
if (net_error == OK) {
num_dns_failures_ = 0;
return;
}
++num_dns_failures_;
if (num_dns_failures_ < kMaximumDnsFailures)
return;
// Disable DnsClient until the next DNS change.
for (JobMap::iterator it = jobs_.begin(); it != jobs_.end(); ++it)
it->second->AbortDnsTask();
dns_client_->SetConfig(DnsConfig());
UMA_HISTOGRAM_BOOLEAN("AsyncDNS.DnsClientEnabled", false);
UMA_HISTOGRAM_CUSTOM_ENUMERATION("AsyncDNS.DnsClientDisabledReason",
std::abs(net_error),
GetAllErrorCodesForUma());
}
void HostResolverImpl::SetDnsClient(scoped_ptr<DnsClient> dns_client) {
if (HaveDnsConfig()) {
for (JobMap::iterator it = jobs_.begin(); it != jobs_.end(); ++it)
it->second->AbortDnsTask();
}
dns_client_ = dns_client.Pass();
if (!dns_client_ || dns_client_->GetConfig() ||
num_dns_failures_ >= kMaximumDnsFailures) {
return;
}
DnsConfig dns_config;
NetworkChangeNotifier::GetDnsConfig(&dns_config);
dns_client_->SetConfig(dns_config);
num_dns_failures_ = 0;
if (dns_config.IsValid())
UMA_HISTOGRAM_BOOLEAN("AsyncDNS.DnsClientEnabled", true);
}
} // namespace net