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Diffstat (limited to 'chromium/net/dns/mdns_cache.h')
-rw-r--r-- | chromium/net/dns/mdns_cache.h | 119 |
1 files changed, 119 insertions, 0 deletions
diff --git a/chromium/net/dns/mdns_cache.h b/chromium/net/dns/mdns_cache.h new file mode 100644 index 00000000000..27a14d8fa44 --- /dev/null +++ b/chromium/net/dns/mdns_cache.h @@ -0,0 +1,119 @@ +// Copyright (c) 2013 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. + +#ifndef NET_DNS_MDNS_CACHE_H_ +#define NET_DNS_MDNS_CACHE_H_ + +#include <map> +#include <string> +#include <vector> + +#include "base/callback.h" +#include "base/memory/scoped_ptr.h" +#include "base/time/time.h" +#include "net/base/net_export.h" + +namespace net { + +class ParsedDnsRecord; +class RecordParsed; + +// mDNS Cache +// This is a cache of mDNS records. It keeps track of expiration times and is +// guaranteed not to return expired records. It also has facilities for timely +// record expiration. +class NET_EXPORT_PRIVATE MDnsCache { + public: + // Key type for the record map. It is a 3-tuple of type, name and optional + // value ordered by type, then name, then optional value. This allows us to + // query for all records of a certain type and name, while also allowing us + // to set records of a certain type, name and optionally value as unique. + class Key { + public: + Key(unsigned type, const std::string& name, const std::string& optional); + Key(const Key&); + Key& operator=(const Key&); + ~Key(); + bool operator<(const Key& key) const; + bool operator==(const Key& key) const; + + unsigned type() const { return type_; } + const std::string& name() const { return name_; } + const std::string& optional() const { return optional_; } + + // Create the cache key corresponding to |record|. + static Key CreateFor(const RecordParsed* record); + private: + unsigned type_; + std::string name_; + std::string optional_; + }; + + typedef base::Callback<void(const RecordParsed*)> RecordRemovedCallback; + + enum UpdateType { + RecordAdded, + RecordChanged, + NoChange + }; + + MDnsCache(); + ~MDnsCache(); + + // Return value indicates whether the record was added, changed + // (existed previously with different value) or not changed (existed + // previously with same value). + UpdateType UpdateDnsRecord(scoped_ptr<const RecordParsed> record); + + // Check cache for record with key |key|. Return the record if it exists, or + // NULL if it doesn't. + const RecordParsed* LookupKey(const Key& key); + + // Return records with type |type| and name |name|. Expired records will not + // be returned. If |type| is zero, return all records with name |name|. + void FindDnsRecords(unsigned type, + const std::string& name, + std::vector<const RecordParsed*>* records, + base::Time now) const; + + // Remove expired records, call |record_removed_callback| for every removed + // record. + void CleanupRecords(base::Time now, + const RecordRemovedCallback& record_removed_callback); + + // Returns a time less than or equal to the next time a record will expire. + // Is updated when CleanupRecords or UpdateDnsRecord are called. Returns + // base::Time when the cache is empty. + base::Time next_expiration() const { return next_expiration_; } + + // Remove a record from the cache. Returns a scoped version of the pointer + // passed in if it was removed, scoped null otherwise. + scoped_ptr<const RecordParsed> RemoveRecord(const RecordParsed* record); + + void Clear(); + + private: + typedef std::map<Key, const RecordParsed*> RecordMap; + + // Get the effective expiration of a cache entry, based on its creation time + // and TTL. Does adjustments so entries with a TTL of zero will have a + // nonzero TTL, as explained in RFC 6762 Section 10.1. + static base::Time GetEffectiveExpiration(const RecordParsed* entry); + + // Get optional part of the DNS key for shared records. For example, in PTR + // records this is the pointed domain, since multiple PTR records may exist + // for the same name. + static std::string GetOptionalFieldForRecord( + const RecordParsed* record); + + RecordMap mdns_cache_; + + base::Time next_expiration_; + + DISALLOW_COPY_AND_ASSIGN(MDnsCache); +}; + +} // namespace net + +#endif // NET_DNS_MDNS_CACHE_H_ |