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/* vim:set ts=4 sw=2 sts=2 et cin: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at */
#ifndef nsHostRecord_h__
#define nsHostRecord_h__
#include "mozilla/AtomicBitfields.h"
#include "mozilla/DataMutex.h"
#include "mozilla/LinkedList.h"
#include "mozilla/net/HTTPSSVC.h"
#include "nsIDNSService.h"
#include "nsIDNSByTypeRecord.h"
#include "PLDHashTable.h"
#include "TRRSkippedReason.h"
class nsHostRecord;
class nsHostResolver;
namespace mozilla {
namespace net {
class HostRecordQueue;
class TRR;
class TRRQuery;
} // namespace net
} // namespace mozilla
* This class is used to notify listeners when a ResolveHost operation is
* complete. Classes that derive it must implement threadsafe nsISupports
* to be able to use RefPtr with this class.
class nsResolveHostCallback
: public mozilla::LinkedListElement<RefPtr<nsResolveHostCallback>>,
public nsISupports {
* OnResolveHostComplete
* this function is called to complete a host lookup initiated by
* nsHostResolver::ResolveHost. it may be invoked recursively from
* ResolveHost or on an unspecified background thread.
* NOTE: it is the responsibility of the implementor of this method
* to handle the callback in a thread safe manner.
* @param resolver
* nsHostResolver object associated with this result
* @param record
* the host record containing the results of the lookup
* @param status
* if successful, |record| contains non-null results
virtual void OnResolveHostComplete(nsHostResolver* resolver,
nsHostRecord* record, nsresult status) = 0;
* EqualsAsyncListener
* Determines if the listener argument matches the listener member var.
* For subclasses not implementing a member listener, should return false.
* For subclasses having a member listener, the function should check if
* they are the same. Used for cases where a pointer to an object
* implementing nsResolveHostCallback is unknown, but a pointer to
* the original listener is known.
* @param aListener
* nsIDNSListener object associated with the original request
virtual bool EqualsAsyncListener(nsIDNSListener* aListener) = 0;
virtual size_t SizeOfIncludingThis(mozilla::MallocSizeOf) const = 0;
virtual ~nsResolveHostCallback() = default;
struct nsHostKey {
const nsCString host;
const nsCString mTrrServer;
uint16_t type = 0;
uint16_t flags = 0;
uint16_t af = 0;
bool pb = false;
const nsCString originSuffix;
explicit nsHostKey(const nsACString& host, const nsACString& aTrrServer,
uint16_t type, uint16_t flags, uint16_t af, bool pb,
const nsACString& originSuffix);
bool operator==(const nsHostKey& other) const;
size_t SizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const;
PLDHashNumber Hash() const;
* nsHostRecord - ref counted object type stored in host resolver cache.
class nsHostRecord : public mozilla::LinkedListElement<RefPtr<nsHostRecord>>,
public nsHostKey,
public nsISupports {
using TRRSkippedReason = mozilla::net::TRRSkippedReason;
virtual size_t SizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const {
return 0;
// Returns the TRR mode encoded by the flags
nsIRequest::TRRMode TRRMode();
// Records the first reason that caused TRR to be skipped or to fail.
void RecordReason(TRRSkippedReason reason) {
if (mTRRSkippedReason == TRRSkippedReason::TRR_UNSET) {
mTRRSkippedReason = reason;
enum DnsPriority {
friend class nsHostResolver;
friend class mozilla::net::HostRecordQueue;
friend class mozilla::net::TRR;
friend class mozilla::net::TRRQuery;
explicit nsHostRecord(const nsHostKey& key);
virtual ~nsHostRecord() = default;
// Mark hostrecord as not usable
void Invalidate();
enum ExpirationStatus {
ExpirationStatus CheckExpiration(const mozilla::TimeStamp& now) const;
// Convenience function for setting the timestamps above (mValidStart,
// mValidEnd, and mGraceStart). valid and grace are durations in seconds.
void SetExpiration(const mozilla::TimeStamp& now, unsigned int valid,
unsigned int grace);
void CopyExpirationTimesAndFlagsFrom(const nsHostRecord* aFromHostRecord);
// Checks if the record is usable (not expired and has a value)
bool HasUsableResult(const mozilla::TimeStamp& now,
uint16_t queryFlags = 0) const;
static DnsPriority GetPriority(uint16_t aFlags);
virtual void Cancel();
virtual bool HasUsableResultInternal(const mozilla::TimeStamp& now,
uint16_t queryFlags) const = 0;
virtual bool RefreshForNegativeResponse() const { return true; }
mozilla::LinkedList<RefPtr<nsResolveHostCallback>> mCallbacks;
bool IsAddrRecord() const {
return type == nsIDNSService::RESOLVE_TYPE_DEFAULT;
// When the record began being valid. Used mainly for bookkeeping.
mozilla::TimeStamp mValidStart;
// When the record is no longer valid (it's time of expiration)
mozilla::TimeStamp mValidEnd;
// When the record enters its grace period. This must be before mValidEnd.
// If a record is in its grace period (and not expired), it will be used
// but a request to refresh it will be made.
mozilla::TimeStamp mGraceStart;
uint32_t mTtl = 0;
// The computed TRR mode that is actually used by the request.
// It is set in nsHostResolver::NameLookup and is based on the mode of the
// default resolver and the TRRMode encoded in the flags.
// The mode into account if the TRR service is disabled,
// parental controls are on, domain matches exclusion list, etc.
nsIRequest::TRRMode mEffectiveTRRMode = nsIRequest::TRR_DEFAULT_MODE;
TRRSkippedReason mTRRSkippedReason = TRRSkippedReason::TRR_UNSET;
TRRSkippedReason mFirstTRRSkippedReason = TRRSkippedReason::TRR_UNSET;
TRRSkippedReason mTRRAFailReason = TRRSkippedReason::TRR_UNSET;
TRRSkippedReason mTRRAAAAFailReason = TRRSkippedReason::TRR_UNSET;
mozilla::DataMutex<RefPtr<mozilla::net::TRRQuery>> mTRRQuery;
// counter of outstanding resolving calls
mozilla::Atomic<int32_t> mResolving{0};
// Number of times we've attempted TRR. Reset when we refresh.
// TRR is attempted at most twice - first attempt and retry.
mozilla::Atomic<int32_t> mTrrAttempts{0};
// True if this record is a cache of a failed lookup. Negative cache
// entries are valid just like any other (though never for more than 60
// seconds), but a use of that negative entry forces an asynchronous refresh.
bool negative = false;
// Explicitly expired
bool mDoomed = false;
// b020e996-f6ab-45e5-9bf5-1da71dd0053a
{ \
0xb020e996, 0xf6ab, 0x45e5, { \
0x9b, 0xf5, 0x1d, 0xa7, 0x1d, 0xd0, 0x05, 0x3a \
} \
class AddrHostRecord final : public nsHostRecord {
using Mutex = mozilla::Mutex;
using DNSResolverType = mozilla::net::DNSResolverType;
/* a fully resolved host record has either a non-null |addr_info| or |addr|
* field. if |addr_info| is null, it implies that the |host| is an IP
* address literal. in which case, |addr| contains the parsed address.
* otherwise, if |addr_info| is non-null, then it contains one or many
* IP addresses corresponding to the given host name. if both |addr_info|
* and |addr| are null, then the given host has not yet been fully resolved.
* |af| is the address family of the record we are querying for.
/* the lock protects |addr_info| and |addr_info_gencnt| because they
* are mutable and accessed by the resolver worker thread and the
* nsDNSService2 class. |addr| doesn't change after it has been
* assigned a value. only the resolver worker thread modifies
* nsHostRecord (and only in nsHostResolver::CompleteLookup);
* the other threads just read it. therefore the resolver worker
* thread doesn't need to lock when reading |addr_info|.
Mutex addr_info_lock{"AddrHostRecord.addr_info_lock"};
// generation count of |addr_info|
int addr_info_gencnt = 0;
RefPtr<mozilla::net::AddrInfo> addr_info;
mozilla::UniquePtr<mozilla::net::NetAddr> addr;
// hold addr_info_lock when calling the blocklist functions
bool Blocklisted(const mozilla::net::NetAddr* query);
void ResetBlocklist();
void ReportUnusable(const mozilla::net::NetAddr* aAddress);
size_t SizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const override;
nsIRequest::TRRMode EffectiveTRRMode() const { return mEffectiveTRRMode; }
friend class nsHostResolver;
friend class mozilla::net::HostRecordQueue;
friend class mozilla::net::TRR;
friend class mozilla::net::TRRQuery;
explicit AddrHostRecord(const nsHostKey& key);
// Checks if the record is usable (not expired and has a value)
bool HasUsableResultInternal(const mozilla::TimeStamp& now,
uint16_t queryFlags) const override;
bool RemoveOrRefresh(bool aTrrToo); // Mark records currently being resolved
// as needed to resolve again.
// Saves the skip reason of a first-attempt TRR lookup and clears
// it to prepare for a retry attempt.
void NotifyRetryingTrr();
void ResolveComplete();
static DnsPriority GetPriority(uint16_t aFlags);
// true if pending and on the queue (not yet given to getaddrinfo())
bool onQueue() { return LoadNative() && isInList(); }
// When the lookups of this record started and their durations
mozilla::TimeStamp mTrrStart;
mozilla::TimeStamp mNativeStart;
mozilla::TimeDuration mTrrDuration;
mozilla::TimeDuration mNativeDuration;
// TRR or ODoH was used on this record
mozilla::Atomic<DNSResolverType> mResolverType{DNSResolverType::Native};
uint8_t mTRRSuccess = 0; // number of successful TRR responses
uint8_t mNativeSuccess = 0; // number of native lookup responses
// clang-format off
MOZ_ATOMIC_BITFIELDS(mAtomicBitfields, 8, (
// true if this record is being resolved "natively", which means that
// it is either on the pending queue or owned by one of the worker threads.
(uint16_t, Native, 1),
(uint16_t, NativeUsed, 1),
// true if off queue and contributing to mActiveAnyThreadCount
(uint16_t, UsingAnyThread, 1),
(uint16_t, GetTtl, 1),
(uint16_t, ResolveAgain, 1)
// clang-format on
// The number of times ReportUnusable() has been called in the record's
// lifetime.
uint32_t mUnusableCount = 0;
// a list of addresses associated with this record that have been reported
// as unusable. the list is kept as a set of strings to make it independent
// of gencnt.
nsTArray<nsCString> mUnusableItems;
// 77b786a7-04be-44f2-987c-ab8aa96676e0
{ \
0x77b786a7, 0x04be, 0x44f2, { \
0x98, 0x7c, 0xab, 0x8a, 0xa9, 0x66, 0x76, 0xe0 \
} \
class TypeHostRecord final : public nsHostRecord,
public nsIDNSTXTRecord,
public nsIDNSHTTPSSVCRecord,
public mozilla::net::DNSHTTPSSVCRecordBase {
size_t SizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const override;
uint32_t GetType();
mozilla::net::TypeRecordResultType GetResults();
friend class nsHostResolver;
friend class mozilla::net::TRRQuery;
explicit TypeHostRecord(const nsHostKey& key);
// Checks if the record is usable (not expired and has a value)
bool HasUsableResultInternal(const mozilla::TimeStamp& now,
uint16_t queryFlags) const override;
bool RefreshForNegativeResponse() const override;
mozilla::net::TypeRecordResultType mResults = AsVariant(mozilla::Nothing());
mozilla::Mutex mResultsLock{"TypeHostRecord.mResultsLock"};
// When the lookups of this record started (for telemetry).
mozilla::TimeStamp mStart;
bool mAllRecordsExcluded = false;
static inline bool IsHighPriority(uint16_t flags) {
return !(flags & (nsHostRecord::DNS_PRIORITY_LOW |
static inline bool IsMediumPriority(uint16_t flags) {
return flags & nsHostRecord::DNS_PRIORITY_MEDIUM;
static inline bool IsLowPriority(uint16_t flags) {
return flags & nsHostRecord::DNS_PRIORITY_LOW;
#endif // nsHostRecord_h__