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373 lines
14 KiB
C++
373 lines
14 KiB
C++
/* vim:set ts=4 sw=4 sts=4 et cin: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef nsHostResolver_h__
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#define nsHostResolver_h__
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#include "nscore.h"
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#include "prclist.h"
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#include "prnetdb.h"
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#include "PLDHashTable.h"
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#include "mozilla/CondVar.h"
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#include "mozilla/Mutex.h"
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#include "nsISupportsImpl.h"
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#include "nsIDNSListener.h"
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#include "nsIDNSService.h"
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#include "nsString.h"
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#include "nsTArray.h"
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#include "GetAddrInfo.h"
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#include "mozilla/net/DNS.h"
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#include "mozilla/net/DashboardTypes.h"
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#include "mozilla/TimeStamp.h"
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class nsHostResolver;
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class nsHostRecord;
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class nsResolveHostCallback;
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#define MAX_RESOLVER_THREADS_FOR_ANY_PRIORITY 3
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#define MAX_RESOLVER_THREADS_FOR_HIGH_PRIORITY 5
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#define MAX_NON_PRIORITY_REQUESTS 150
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#define MAX_RESOLVER_THREADS (MAX_RESOLVER_THREADS_FOR_ANY_PRIORITY + \
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MAX_RESOLVER_THREADS_FOR_HIGH_PRIORITY)
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struct nsHostKey
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{
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const char *host;
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uint16_t flags;
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uint16_t af;
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const char *netInterface;
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};
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/**
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* nsHostRecord - ref counted object type stored in host resolver cache.
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*/
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class nsHostRecord : public PRCList, public nsHostKey
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{
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typedef mozilla::Mutex Mutex;
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public:
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NS_INLINE_DECL_THREADSAFE_REFCOUNTING(nsHostRecord)
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/* instantiates a new host record */
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static nsresult Create(const nsHostKey *key, nsHostRecord **record);
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/* a fully resolved host record has either a non-null |addr_info| or |addr|
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* field. if |addr_info| is null, it implies that the |host| is an IP
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* address literal. in which case, |addr| contains the parsed address.
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* otherwise, if |addr_info| is non-null, then it contains one or many
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* IP addresses corresponding to the given host name. if both |addr_info|
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* and |addr| are null, then the given host has not yet been fully resolved.
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* |af| is the address family of the record we are querying for.
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*/
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/* the lock protects |addr_info| and |addr_info_gencnt| because they
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* are mutable and accessed by the resolver worker thread and the
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* nsDNSService2 class. |addr| doesn't change after it has been
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* assigned a value. only the resolver worker thread modifies
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* nsHostRecord (and only in nsHostResolver::OnLookupComplete);
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* the other threads just read it. therefore the resolver worker
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* thread doesn't need to lock when reading |addr_info|.
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*/
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Mutex addr_info_lock;
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int addr_info_gencnt; /* generation count of |addr_info| */
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mozilla::net::AddrInfo *addr_info;
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mozilla::net::NetAddr *addr;
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bool negative; /* True if this record is a cache of a failed lookup.
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Negative cache entries are valid just like any other
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(though never for more than 60 seconds), but a use
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of that negative entry forces an asynchronous refresh. */
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enum ExpirationStatus {
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EXP_VALID,
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EXP_GRACE,
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EXP_EXPIRED,
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};
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ExpirationStatus CheckExpiration(const mozilla::TimeStamp& now) const;
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// When the record began being valid. Used mainly for bookkeeping.
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mozilla::TimeStamp mValidStart;
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// When the record is no longer valid (it's time of expiration)
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mozilla::TimeStamp mValidEnd;
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// When the record enters its grace period. This must be before mValidEnd.
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// If a record is in its grace period (and not expired), it will be used
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// but a request to refresh it will be made.
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mozilla::TimeStamp mGraceStart;
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// Convenience function for setting the timestamps above (mValidStart,
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// mValidEnd, and mGraceStart). valid and grace are durations in seconds.
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void SetExpiration(const mozilla::TimeStamp& now, unsigned int valid,
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unsigned int grace);
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void CopyExpirationTimesAndFlagsFrom(const nsHostRecord *aFromHostRecord);
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// Checks if the record is usable (not expired and has a value)
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bool HasUsableResult(const mozilla::TimeStamp& now, uint16_t queryFlags = 0) const;
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// hold addr_info_lock when calling the blacklist functions
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bool Blacklisted(mozilla::net::NetAddr *query);
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void ResetBlacklist();
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void ReportUnusable(mozilla::net::NetAddr *addr);
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size_t SizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const;
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enum DnsPriority {
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DNS_PRIORITY_LOW,
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DNS_PRIORITY_MEDIUM,
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DNS_PRIORITY_HIGH,
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};
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static DnsPriority GetPriority(uint16_t aFlags);
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bool RemoveOrRefresh(); // Mark records currently being resolved as needed
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// to resolve again.
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private:
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friend class nsHostResolver;
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PRCList callbacks; /* list of callbacks */
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bool resolving; /* true if this record is being resolved, which means
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* that it is either on the pending queue or owned by
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* one of the worker threads. */
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bool onQueue; /* true if pending and on the queue (not yet given to getaddrinfo())*/
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bool usingAnyThread; /* true if off queue and contributing to mActiveAnyThreadCount */
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bool mDoomed; /* explicitly expired */
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#if TTL_AVAILABLE
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bool mGetTtl;
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#endif
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// The number of times ReportUnusable() has been called in the record's
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// lifetime.
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uint32_t mBlacklistedCount;
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// when the results from this resolve is returned, it is not to be
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// trusted, but instead a new resolve must be made!
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bool mResolveAgain;
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// a list of addresses associated with this record that have been reported
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// as unusable. the list is kept as a set of strings to make it independent
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// of gencnt.
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nsTArray<nsCString> mBlacklistedItems;
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explicit nsHostRecord(const nsHostKey *key); /* use Create() instead */
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~nsHostRecord();
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};
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/**
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* ResolveHost callback object. It's PRCList members are used by
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* the nsHostResolver and should not be used by anything else.
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*/
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class NS_NO_VTABLE nsResolveHostCallback : public PRCList
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{
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public:
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/**
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* OnLookupComplete
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*
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* this function is called to complete a host lookup initiated by
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* nsHostResolver::ResolveHost. it may be invoked recursively from
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* ResolveHost or on an unspecified background thread.
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*
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* NOTE: it is the responsibility of the implementor of this method
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* to handle the callback in a thread safe manner.
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*
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* @param resolver
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* nsHostResolver object associated with this result
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* @param record
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* the host record containing the results of the lookup
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* @param status
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* if successful, |record| contains non-null results
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*/
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virtual void OnLookupComplete(nsHostResolver *resolver,
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nsHostRecord *record,
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nsresult status) = 0;
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/**
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* EqualsAsyncListener
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*
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* Determines if the listener argument matches the listener member var.
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* For subclasses not implementing a member listener, should return false.
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* For subclasses having a member listener, the function should check if
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* they are the same. Used for cases where a pointer to an object
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* implementing nsResolveHostCallback is unknown, but a pointer to
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* the original listener is known.
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*
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* @param aListener
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* nsIDNSListener object associated with the original request
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*/
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virtual bool EqualsAsyncListener(nsIDNSListener *aListener) = 0;
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virtual size_t SizeOfIncludingThis(mozilla::MallocSizeOf) const = 0;
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};
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/**
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* nsHostResolver - an asynchronous host name resolver.
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*/
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class nsHostResolver
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{
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typedef mozilla::CondVar CondVar;
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typedef mozilla::Mutex Mutex;
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public:
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/**
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* host resolver instances are reference counted.
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*/
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NS_INLINE_DECL_THREADSAFE_REFCOUNTING(nsHostResolver)
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/**
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* creates an addref'd instance of a nsHostResolver object.
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*/
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static nsresult Create(uint32_t maxCacheEntries, // zero disables cache
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uint32_t defaultCacheEntryLifetime, // seconds
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uint32_t defaultGracePeriod, // seconds
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nsHostResolver **resolver);
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/**
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* puts the resolver in the shutdown state, which will cause any pending
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* callbacks to be detached. any future calls to ResolveHost will fail.
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*/
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void Shutdown();
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/**
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* resolve the given hostname asynchronously. the caller can synthesize
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* a synchronous host lookup using a lock and a cvar. as noted above
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* the callback will occur re-entrantly from an unspecified thread. the
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* host lookup cannot be canceled (cancelation can be layered above this
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* by having the callback implementation return without doing anything).
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*/
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nsresult ResolveHost(const char *hostname,
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uint16_t flags,
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uint16_t af,
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const char *netInterface,
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nsResolveHostCallback *callback);
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/**
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* removes the specified callback from the nsHostRecord for the given
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* hostname, flags, and address family. these parameters should correspond
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* to the parameters passed to ResolveHost. this function executes the
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* callback if the callback is still pending with the given status.
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*/
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void DetachCallback(const char *hostname,
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uint16_t flags,
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uint16_t af,
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const char *netInterface,
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nsResolveHostCallback *callback,
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nsresult status);
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/**
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* Cancels an async request associated with the hostname, flags,
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* address family and listener. Cancels first callback found which matches
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* these criteria. These parameters should correspond to the parameters
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* passed to ResolveHost. If this is the last callback associated with the
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* host record, it is removed from any request queues it might be on.
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*/
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void CancelAsyncRequest(const char *host,
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uint16_t flags,
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uint16_t af,
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const char *netInterface,
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nsIDNSListener *aListener,
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nsresult status);
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/**
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* values for the flags parameter passed to ResolveHost and DetachCallback
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* that may be bitwise OR'd together.
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*
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* NOTE: in this implementation, these flags correspond exactly in value
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* to the flags defined on nsIDNSService.
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*/
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enum {
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RES_BYPASS_CACHE = nsIDNSService::RESOLVE_BYPASS_CACHE,
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RES_CANON_NAME = nsIDNSService::RESOLVE_CANONICAL_NAME,
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RES_PRIORITY_MEDIUM = nsIDNSService::RESOLVE_PRIORITY_MEDIUM,
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RES_PRIORITY_LOW = nsIDNSService::RESOLVE_PRIORITY_LOW,
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RES_SPECULATE = nsIDNSService::RESOLVE_SPECULATE,
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//RES_DISABLE_IPV6 = nsIDNSService::RESOLVE_DISABLE_IPV6, // Not used
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RES_OFFLINE = nsIDNSService::RESOLVE_OFFLINE,
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//RES_DISABLE_IPv4 = nsIDNSService::RESOLVE_DISABLE_IPV4, // Not Used
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RES_ALLOW_NAME_COLLISION = nsIDNSService::RESOLVE_ALLOW_NAME_COLLISION
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};
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size_t SizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const;
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/**
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* Flush the DNS cache.
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*/
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void FlushCache();
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private:
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explicit nsHostResolver(uint32_t maxCacheEntries,
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uint32_t defaultCacheEntryLifetime,
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uint32_t defaultGracePeriod);
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~nsHostResolver();
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nsresult Init();
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nsresult IssueLookup(nsHostRecord *);
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bool GetHostToLookup(nsHostRecord **m);
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enum LookupStatus {
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LOOKUP_OK,
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LOOKUP_RESOLVEAGAIN,
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};
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LookupStatus OnLookupComplete(nsHostRecord *, nsresult, mozilla::net::AddrInfo *);
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void DeQueue(PRCList &aQ, nsHostRecord **aResult);
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void ClearPendingQueue(PRCList *aPendingQueue);
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nsresult ConditionallyCreateThread(nsHostRecord *rec);
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/**
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* Starts a new lookup in the background for entries that are in the grace
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* period with a failed connect or all cached entries are negative.
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*/
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nsresult ConditionallyRefreshRecord(nsHostRecord *rec, const char *host);
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static void MoveQueue(nsHostRecord *aRec, PRCList &aDestQ);
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static void ThreadFunc(void *);
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enum {
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METHOD_HIT = 1,
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METHOD_RENEWAL = 2,
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METHOD_NEGATIVE_HIT = 3,
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METHOD_LITERAL = 4,
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METHOD_OVERFLOW = 5,
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METHOD_NETWORK_FIRST = 6,
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METHOD_NETWORK_SHARED = 7
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};
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uint32_t mMaxCacheEntries;
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uint32_t mDefaultCacheLifetime; // granularity seconds
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uint32_t mDefaultGracePeriod; // granularity seconds
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mutable Mutex mLock; // mutable so SizeOfIncludingThis can be const
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CondVar mIdleThreadCV;
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PLDHashTable mDB;
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PRCList mHighQ;
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PRCList mMediumQ;
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PRCList mLowQ;
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PRCList mEvictionQ;
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uint32_t mEvictionQSize;
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PRTime mCreationTime;
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PRIntervalTime mLongIdleTimeout;
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PRIntervalTime mShortIdleTimeout;
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mozilla::Atomic<bool> mShutdown;
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mozilla::Atomic<uint32_t> mNumIdleThreads;
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mozilla::Atomic<uint32_t> mThreadCount;
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mozilla::Atomic<uint32_t> mActiveAnyThreadCount;
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mozilla::Atomic<uint32_t> mPendingCount;
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// Set the expiration time stamps appropriately.
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void PrepareRecordExpiration(nsHostRecord* rec) const;
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public:
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/*
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* Called by the networking dashboard via the DnsService2
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*/
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void GetDNSCacheEntries(nsTArray<mozilla::net::DNSCacheEntries> *);
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};
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#endif // nsHostResolver_h__
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