// 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_impl.h" #if defined(OS_WIN) #include #elif defined(OS_POSIX) #include #endif #include #include #include #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/message_loop_proxy.h" #include "base/metrics/field_trial.h" #include "base/metrics/histogram.h" #include "base/stl_util.h" #include "base/strings/string_util.h" #include "base/strings/utf_string_conversions.h" #include "base/threading/worker_pool.h" #include "base/time/time.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/dns_util.h" #include "net/base/host_port_pair.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 "net/dns/host_resolver_proc.h" #include "net/socket/client_socket_factory.h" #include "net/udp/datagram_client_socket.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; // 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 // 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 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)); } 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); } // Attempts to connect a UDP socket to |dest|:53. bool IsGloballyReachable(const IPAddressNumber& dest, const BoundNetLog& net_log) { scoped_ptr socket( ClientSocketFactory::GetDefaultFactory()->CreateDatagramClientSocket( DatagramSocket::DEFAULT_BIND, RandIntCallback(), 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(endpoint.GetFamily() == ADDRESS_FAMILY_IPV6); const IPAddressNumber& address = endpoint.address(); bool is_link_local = (address[0] == 0xFE) && ((address[1] & 0xC0) == 0x80); if (is_link_local) return false; const uint8 kTeredoPrefix[] = { 0x20, 0x01, 0, 0 }; bool is_teredo = std::equal(kTeredoPrefix, kTeredoPrefix + arraysize(kTeredoPrefix), address.begin()); if (is_teredo) return false; return true; } // 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); } 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 StartsWithASCII(group_name, "AsyncDnsNoFallback", false); return kDefault; } //----------------------------------------------------------------------------- AddressList EnsurePortOnAddressList(const AddressList& list, uint16 port) { if (list.empty() || list.front().port() == port) return list; return AddressList::CopyWithPort(list, port); } // Returns true if |addresses| contains only IPv4 loopback addresses. bool IsAllIPv4Loopback(const AddressList& addresses) { for (unsigned i = 0; i < addresses.size(); ++i) { const IPAddressNumber& address = addresses[i].address(); switch (addresses[i].GetFamily()) { case ADDRESS_FAMILY_IPV4: if (address[0] != 127) return false; break; case ADDRESS_FAMILY_IPV6: return false; default: NOTREACHED(); return false; } } return true; } // Creates NetLog parameters when the resolve failed. base::Value* NetLogProcTaskFailedCallback(uint32 attempt_number, int net_error, int os_error, NetLog::LogLevel /* log_level */) { 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_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", base::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 */) { base::DictionaryValue* dict = new base::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 */) { base::DictionaryValue* dict = new base::DictionaryValue(); source.AddToEventParameters(dict); dict->SetString("host", info->host_port_pair().ToString()); dict->SetInteger("address_family", static_cast(info->address_family())); dict->SetBoolean("allow_cached_response", info->allow_cached_response()); dict->SetBoolean("is_speculative", info->is_speculative()); 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 */) { base::DictionaryValue* dict = new base::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 */) { base::DictionaryValue* dict = new base::DictionaryValue(); source.AddToEventParameters(dict); dict->SetString("priority", RequestPriorityToString(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(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 //----------------------------------------------------------------------------- const unsigned HostResolverImpl::kMaximumDnsFailures = 16; // 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, RequestPriority priority, const CompletionCallback& callback, AddressList* addresses) : source_net_log_(source_net_log), request_net_log_(request_net_log), info_(info), priority_(priority), 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_; } RequestPriority priority() const { return priority_; } base::TimeTicks request_time() const { return request_time_; } private: BoundNetLog source_net_log_; BoundNetLog request_net_log_; // The request info that started the request. const RequestInfo info_; // TODO(akalin): Support reprioritization. const RequestPriority priority_; // 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 { public: typedef base::Callback 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.get()) params_.resolver_proc = HostResolverProc::GetDefault(); // If default is unset, use the system proc. if (!params_.resolver_proc.get()) params_.resolver_proc = new SystemHostResolverProc(); } 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() {} void StartLookupAttempt() { 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()); // If results are empty, we should return an error. bool empty_list_on_ok = (error == OK && results.empty()); UMA_HISTOGRAM_BOOLEAN("DNS.EmptyAddressListAndNoError", empty_list_on_ok); if (empty_list_on_ok) error = ERR_NAME_NOT_RESOLVED; 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; } UMA_HISTOGRAM_CUSTOM_ENUMERATION(kOSErrorsForGetAddrinfoHistogramName, std::abs(os_error), GetAllGetAddrinfoOSErrors()); } DCHECK_LT(category, static_cast(RESOLVE_MAX)); // Be sure it was set. UMA_HISTOGRAM_ENUMERATION("DNS.ResolveCategory", category, RESOLVE_MAX); } 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 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 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& resolver) : resolver_(resolver), result_(false) { DCHECK(resolver.get()); 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_.get()) return; resolver_->SetHaveOnlyLoopbackAddresses(result_); } // Used/set only on origin thread. base::WeakPtr 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 { public: class Delegate { public: virtual void OnDnsTaskComplete(base::TimeTicks start_time, int net_error, const AddressList& addr_list, base::TimeDelta ttl) = 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; protected: Delegate() {} virtual ~Delegate() {} }; DnsTask(DnsClient* client, const Key& key, Delegate* delegate, const BoundNetLog& job_net_log) : client_(client), key_(key), delegate_(delegate), net_log_(job_net_log), num_completed_transactions_(0), task_start_time_(base::TimeTicks::Now()) { DCHECK(client); DCHECK(delegate_); } bool needs_two_transactions() const { return key_.address_family == ADDRESS_FAMILY_UNSPECIFIED; } bool needs_another_transaction() const { return needs_two_transactions() && !transaction_aaaa_; } void StartFirstTransaction() { DCHECK_EQ(0u, num_completed_transactions_); net_log_.BeginEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_DNS_TASK); if (key_.address_family == ADDRESS_FAMILY_IPV6) { StartAAAA(); } else { StartA(); } } void StartSecondTransaction() { DCHECK(needs_two_transactions()); StartAAAA(); } private: void StartA() { DCHECK(!transaction_a_); DCHECK_NE(ADDRESS_FAMILY_IPV6, key_.address_family); transaction_a_ = CreateTransaction(ADDRESS_FAMILY_IPV4); transaction_a_->Start(); } void StartAAAA() { DCHECK(!transaction_aaaa_); DCHECK_NE(ADDRESS_FAMILY_IPV4, key_.address_family); transaction_aaaa_ = CreateTransaction(ADDRESS_FAMILY_IPV6); transaction_aaaa_->Start(); } scoped_ptr CreateTransaction(AddressFamily family) { DCHECK_NE(ADDRESS_FAMILY_UNSPECIFIED, family); return client_->GetTransactionFactory()->CreateTransaction( key_.hostname, family == ADDRESS_FAMILY_IPV6 ? dns_protocol::kTypeAAAA : dns_protocol::kTypeA, base::Bind(&DnsTask::OnTransactionComplete, base::Unretained(this), base::TimeTicks::Now()), net_log_); } void OnTransactionComplete(const base::TimeTicks& start_time, DnsTransaction* transaction, int net_error, const DnsResponse* response) { DCHECK(transaction); base::TimeDelta duration = base::TimeTicks::Now() - start_time; if (net_error != OK) { DNS_HISTOGRAM("AsyncDNS.TransactionFailure", duration); OnFailure(net_error, DnsResponse::DNS_PARSE_OK); return; } DNS_HISTOGRAM("AsyncDNS.TransactionSuccess", duration); switch (transaction->GetType()) { case dns_protocol::kTypeA: DNS_HISTOGRAM("AsyncDNS.TransactionSuccess_A", duration); break; case dns_protocol::kTypeAAAA: DNS_HISTOGRAM("AsyncDNS.TransactionSuccess_AAAA", duration); break; } 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; } ++num_completed_transactions_; if (num_completed_transactions_ == 1) { ttl_ = ttl; } else { ttl_ = std::min(ttl_, ttl); } if (transaction->GetType() == dns_protocol::kTypeA) { DCHECK_EQ(transaction_a_.get(), transaction); // Place IPv4 addresses after IPv6. addr_list_.insert(addr_list_.end(), addr_list.begin(), addr_list.end()); } else { DCHECK_EQ(transaction_aaaa_.get(), transaction); // Place IPv6 addresses before IPv4. addr_list_.insert(addr_list_.begin(), addr_list.begin(), addr_list.end()); } if (needs_two_transactions() && num_completed_transactions_ == 1) { // No need to repeat the suffix search. key_.hostname = transaction->GetHostname(); delegate_->OnFirstDnsTransactionComplete(); return; } 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 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 (addr_list_.size() > 1 && addr_list_[0].GetFamily() == ADDRESS_FAMILY_IPV6) { // Sort addresses if needed. Sort could complete synchronously. client_->GetAddressSorter()->Sort( addr_list_, base::Bind(&DnsTask::OnSortComplete, AsWeakPtr(), base::TimeTicks::Now())); } else { OnSuccess(addr_list_); } } void OnSortComplete(base::TimeTicks start_time, 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); } 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)); delegate_->OnDnsTaskComplete(task_start_time_, net_error, AddressList(), base::TimeDelta()); } void OnSuccess(const AddressList& addr_list) { net_log_.EndEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_DNS_TASK, addr_list.CreateNetLogCallback()); delegate_->OnDnsTaskComplete(task_start_time_, OK, addr_list, ttl_); } DnsClient* client_; Key key_; // The listener to the results of this DnsTask. Delegate* delegate_; const BoundNetLog net_log_; scoped_ptr transaction_a_; scoped_ptr transaction_aaaa_; unsigned num_completed_transactions_; // These are updated as each transaction completes. base::TimeDelta ttl_; // IPv6 addresses must appear first in the list. AddressList addr_list_; base::TimeTicks task_start_time_; DISALLOW_COPY_AND_ASSIGN(DnsTask); }; //----------------------------------------------------------------------------- // Aggregates all Requests for the same Key. Dispatched via PriorityDispatch. class HostResolverImpl::Job : public PrioritizedDispatcher::Job, public HostResolverImpl::DnsTask::Delegate { public: // Creates new job for |key| where |request_net_log| is bound to the // request that spawned it. Job(const base::WeakPtr& 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), num_occupied_job_slots_(0), 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. KillDnsTask(); 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. 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(scoped_ptr req) { DCHECK_EQ(key_.hostname, req->info().hostname()); req->set_job(this); priority_tracker_.Add(req->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_.get()) 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->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_) { KillDnsTask(); 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 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()) { if (priority() != static_cast(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_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(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); } bool system_only = (key_.host_resolver_flags & HOST_RESOLVER_SYSTEM_ONLY) != 0; // Caution: Job::Start must not complete synchronously. if (!system_only && 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 (!resolver_->resolved_known_ipv6_hostname_ && net_error == OK && key_.address_family == ADDRESS_FAMILY_UNSPECIFIED) { if (key_.hostname == "www.google.com") { resolver_->resolved_known_ipv6_hostname_ = true; bool got_ipv6_address = false; for (size_t i = 0; i < addr_list.size(); ++i) { if (addr_list[i].GetFamily() == ADDRESS_FAMILY_IPV6) { got_ipv6_address = true; break; } } UMA_HISTOGRAM_BOOLEAN("Net.UnspecResolvedIPv6", got_ipv6_address); } } 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_, this, net_log_)); dns_task_->StartFirstTransaction(); // Schedule a second transaction, if needed. if (dns_task_->needs_two_transactions()) Schedule(true); } 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& dns_task, base::TimeDelta duration, int net_error) { DNS_HISTOGRAM("AsyncDNS.ResolveFail", duration); if (dns_task == NULL) return; dns_task_error_ = net_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_->fallback_to_proctask_) { KillDnsTask(); StartProcTask(); } else { UmaAsyncDnsResolveStatus(RESOLVE_STATUS_FAIL); CompleteRequestsWithError(net_error); } } // HostResolverImpl::DnsTask::Delegate implementation: virtual void OnDnsTaskComplete(base::TimeTicks start_time, int net_error, const AddressList& addr_list, base::TimeDelta ttl) OVERRIDE { DCHECK(is_dns_running()); base::TimeDelta duration = base::TimeTicks::Now() - start_time; if (net_error != OK) { OnDnsTaskFailure(dns_task_->AsWeakPtr(), duration, net_error); return; } DNS_HISTOGRAM("AsyncDNS.ResolveSuccess", duration); // Log DNS lookups based on |address_family|. switch(key_.address_family) { case ADDRESS_FAMILY_IPV4: DNS_HISTOGRAM("AsyncDNS.ResolveSuccess_FAMILY_IPV4", duration); break; case ADDRESS_FAMILY_IPV6: DNS_HISTOGRAM("AsyncDNS.ResolveSuccess_FAMILY_IPV6", duration); break; case ADDRESS_FAMILY_UNSPECIFIED: DNS_HISTOGRAM("AsyncDNS.ResolveSuccess_FAMILY_UNSPEC", duration); break; } 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); } virtual 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(); } // Performs Job's last rites. Completes all Requests. Deletes this. void CompleteRequests(const HostCache::Entry& entry, base::TimeDelta ttl) { 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, the job deletes itself when CompleteRequests // is done. scoped_ptr self_deleter(this); resolver_->RemoveJob(this); if (is_running()) { if (is_proc_running()) { DCHECK(!is_queued()); proc_task_->Cancel(); proc_task_ = NULL; } KillDnsTask(); // 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_.get()) 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 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_; // 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::TimeTicks creation_time_; base::TimeTicks priority_change_time_; BoundNetLog net_log_; // Resolves the host using a HostResolverProc. scoped_refptr proc_task_; // Resolves the host using a DnsTransaction. scoped_ptr 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 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), net_log_(net_log), default_address_family_(ADDRESS_FAMILY_UNSPECIFIED), weak_ptr_factory_(this), probe_weak_ptr_factory_(this), received_dns_config_(false), num_dns_failures_(0), probe_ipv6_support_(true), use_local_ipv6_(false), resolved_known_ipv6_hostname_(false), additional_resolver_flags_(0), fallback_to_proctask_(true) { DCHECK_GE(dispatcher_.num_priorities(), static_cast(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) && !defined(OS_ANDROID) 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) EnsureDnsReloaderInit(); #endif { DnsConfig dns_config; NetworkChangeNotifier::GetDnsConfig(&dns_config); received_dns_config_ = dns_config.IsValid(); // Conservatively assume local IPv6 is needed when DnsConfig is not valid. use_local_ipv6_ = !dns_config.IsValid() || dns_config.use_local_ipv6; } fallback_to_proctask_ = !ConfigureAsyncDnsNoFallbackFieldTrial(); } HostResolverImpl::~HostResolverImpl() { // Prevent the dispatcher from starting new jobs. dispatcher_.SetLimitsToZero(); // It's now safe for Jobs to call KillDsnTask on destruction, because // OnJobComplete will not start any new jobs. 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, RequestPriority priority, AddressList* addresses, const CompletionCallback& callback, RequestHandle* out_req, const BoundNetLog& source_net_log) { DCHECK(addresses); DCHECK(CalledOnValidThread()); DCHECK_EQ(false, callback.is_null()); // Check that the caller supplied a valid hostname to resolve. std::string labeled_hostname; if (!DNSDomainFromDot(info.hostname(), &labeled_hostname)) return ERR_NAME_NOT_RESOLVED; // 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, request_net_log); 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()) { job = new Job(weak_ptr_factory_.GetWeakPtr(), key, priority, request_net_log); job->Schedule(false); // Check for queue overflow. if (dispatcher_.num_queued_jobs() > max_queued_jobs_) { Job* evicted = static_cast(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 req(new Request( source_net_log, request_net_log, info, priority, callback, addresses)); if (out_req) *out_req = reinterpret_cast(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, request_net_log); 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(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; probe_ipv6_support_ = false; } AddressFamily HostResolverImpl::GetDefaultAddressFamily() const { return default_address_family_; } 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()); } #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 base::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) && !probe_ipv6_support_; *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; addresses->clear(); // HOSTS lookups are case-insensitive. std::string hostname = StringToLowerASCII(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. if (key.address_family == ADDRESS_FAMILY_IPV6 || key.address_family == ADDRESS_FAMILY_UNSPECIFIED) { DnsHosts::const_iterator it = hosts.find( DnsHostsKey(hostname, ADDRESS_FAMILY_IPV6)); if (it != hosts.end()) addresses->push_back(IPEndPoint(it->second, info.port())); } if (key.address_family == ADDRESS_FAMILY_IPV4 || key.address_family == ADDRESS_FAMILY_UNSPECIFIED) { DnsHosts::const_iterator it = hosts.find( DnsHostsKey(hostname, ADDRESS_FAMILY_IPV4)); if (it != hosts.end()) addresses->push_back(IPEndPoint(it->second, info.port())); } // 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.address_family = ADDRESS_FAMILY_UNSPECIFIED; new_key.host_resolver_flags &= ~HOST_RESOLVER_DEFAULT_FAMILY_SET_DUE_TO_NO_IPV6; return ServeFromHosts(new_key, info, addresses); } return !addresses->empty(); } 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::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 BoundNetLog& net_log) const { HostResolverFlags effective_flags = info.host_resolver_flags() | additional_resolver_flags_; AddressFamily effective_address_family = info.address_family(); if (info.address_family() == ADDRESS_FAMILY_UNSPECIFIED) { if (probe_ipv6_support_ && !use_local_ipv6_) { base::TimeTicks start_time = base::TimeTicks::Now(); // Google DNS address. const uint8 kIPv6Address[] = { 0x20, 0x01, 0x48, 0x60, 0x48, 0x60, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x88, 0x88 }; IPAddressNumber address(kIPv6Address, kIPv6Address + arraysize(kIPv6Address)); BoundNetLog probe_net_log = BoundNetLog::Make( net_log.net_log(), NetLog::SOURCE_IPV6_REACHABILITY_CHECK); probe_net_log.BeginEvent(NetLog::TYPE_IPV6_REACHABILITY_CHECK, net_log.source().ToEventParametersCallback()); bool rv6 = IsGloballyReachable(address, probe_net_log); probe_net_log.EndEvent(NetLog::TYPE_IPV6_REACHABILITY_CHECK); if (rv6) net_log.AddEvent(NetLog::TYPE_HOST_RESOLVER_IMPL_IPV6_SUPPORTED); UMA_HISTOGRAM_TIMES("Net.IPv6ConnectDuration", base::TimeTicks::Now() - start_time); if (rv6) { UMA_HISTOGRAM_BOOLEAN("Net.IPv6ConnectSuccessMatch", default_address_family_ == ADDRESS_FAMILY_UNSPECIFIED); } else { UMA_HISTOGRAM_BOOLEAN("Net.IPv6ConnectFailureMatch", default_address_family_ != ADDRESS_FAMILY_UNSPECIFIED); effective_address_family = ADDRESS_FAMILY_IPV4; effective_flags |= HOST_RESOLVER_DEFAULT_FAMILY_SET_DUE_TO_NO_IPV6; } } else { effective_address_family = default_address_family_; } } 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 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; } } // 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 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(); jobs_to_abort[i] = NULL; } if (self) dispatcher_.SetLimits(limits); } void HostResolverImpl::AbortDnsTasks() { // 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 (JobMap::iterator it = jobs_.begin(); it != jobs_.end(); ++it) it->second->AbortDnsTask(); dispatcher_.SetLimits(limits); } 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 self = weak_ptr_factory_.GetWeakPtr(); for (JobMap::iterator it = jobs_.begin(); self.get() && it != jobs_.end();) { Job* job = it->second; ++it; // This could remove |job| from |jobs_|, but iterator will remain valid. job->ServeFromHosts(); } } void HostResolverImpl::OnIPAddressChanged() { resolved_known_ipv6_hostname_ = false; // Abandon all ProbeJobs. probe_weak_ptr_factory_.InvalidateWeakPtrs(); if (cache_.get()) cache_->clear(); #if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_ANDROID) 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(); // 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()) { dns_client_->SetConfig(dns_config); if (dns_client_->GetConfig()) 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 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(); } bool HostResolverImpl::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_.get() != NULL) && (dns_client_->GetConfig() != NULL) && !(proc_params_.resolver_proc.get() == NULL && HostResolverProc::GetDefault() != 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. Must be done before aborting // DnsTasks, since doing so may start new jobs. dns_client_->SetConfig(DnsConfig()); // Switch jobs with active DnsTasks over to using ProcTasks. AbortDnsTasks(); UMA_HISTOGRAM_BOOLEAN("AsyncDNS.DnsClientEnabled", false); UMA_HISTOGRAM_CUSTOM_ENUMERATION("AsyncDNS.DnsClientDisabledReason", std::abs(net_error), GetAllErrorCodesForUma()); } void HostResolverImpl::SetDnsClient(scoped_ptr dns_client) { // DnsClient and config must be updated before aborting DnsTasks, since doing // so may start new jobs. dns_client_ = dns_client.Pass(); if (dns_client_ && !dns_client_->GetConfig() && num_dns_failures_ < kMaximumDnsFailures) { DnsConfig dns_config; NetworkChangeNotifier::GetDnsConfig(&dns_config); dns_client_->SetConfig(dns_config); num_dns_failures_ = 0; if (dns_client_->GetConfig()) UMA_HISTOGRAM_BOOLEAN("AsyncDNS.DnsClientEnabled", true); } AbortDnsTasks(); } } // namespace net