pdns/dnsdist-cache.hh

   1 /*
   2  * This file is part of PowerDNS or dnsdist.
   3  * Copyright -- PowerDNS.COM B.V. and its contributors
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of version 2 of the GNU General Public License as
   7  * published by the Free Software Foundation.
   8  *
   9  * In addition, for the avoidance of any doubt, permission is granted to
  10  * link this program with OpenSSL and to (re)distribute the binaries
  11  * produced as the result of such linking.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  21  */
  22 #pragma once
  23
  24 #include <atomic>
  25 #include <unordered_map>
  26 #include "lock.hh"
  27
  28 struct DNSQuestion;
  29
  30 class DNSDistPacketCache : boost::noncopyable
  31 {
  32 public:
  33   DNSDistPacketCache(size_t maxEntries, uint32_t maxTTL=86400, uint32_t minTTL=0, uint32_t tempFailureTTL=60, uint32_t staleTTL=60);
  34   ~DNSDistPacketCache();
  35
  36   void insert(uint32_t key, const DNSName& qname, uint16_t qtype, uint16_t qclass, const char* response, uint16_t responseLen, bool tcp, uint8_t rcode);
  37   bool get(const DNSQuestion& dq, uint16_t consumed, uint16_t queryId, char* response, uint16_t* responseLen, uint32_t* keyOut, uint32_t allowExpired=0, bool skipAging=false);
  38   void purgeExpired(size_t upTo=0);
  39   void expunge(size_t upTo=0);
  40   void expungeByName(const DNSName& name, uint16_t qtype=QType::ANY, bool suffixMatch=false);
  41   bool isFull();
  42   string toString();
  43   uint64_t getSize() const { return d_map.size(); }
  44   uint64_t getHits() const { return d_hits; }
  45   uint64_t getMisses() const { return d_misses; }
  46   uint64_t getDeferredLookups() const { return d_deferredLookups; }
  47   uint64_t getDeferredInserts() const { return d_deferredInserts; }
  48   uint64_t getLookupCollisions() const { return d_lookupCollisions; }
  49   uint64_t getInsertCollisions() const { return d_insertCollisions; }
  50   uint64_t getMaxEntries() const { return d_maxEntries; }
  51   uint64_t getTTLTooShorts() const { return d_ttlTooShorts; }
  52   uint64_t getEntriesCount();
  53
  54   static uint32_t getMinTTL(const char* packet, uint16_t length);
  55
  56 private:
  57
  58   struct CacheValue
  59   {
  60     time_t getTTD() const { return validity; }
  61     std::string value;
  62     DNSName qname;
  63     uint16_t qtype{0};
  64     uint16_t qclass{0};
  65     time_t added{0};
  66     time_t validity{0};
  67     uint16_t len{0};
  68     bool tcp{false};
  69   };
  70
  71   static uint32_t getKey(const DNSName& qname, uint16_t consumed, const unsigned char* packet, uint16_t packetLen, bool tcp);
  72   static bool cachedValueMatches(const CacheValue& cachedValue, const DNSName& qname, uint16_t qtype, uint16_t qclass, bool tcp);
  73
  74   pthread_rwlock_t d_lock;
  75   std::unordered_map<uint32_t,CacheValue> d_map;
  76   std::atomic<uint64_t> d_deferredLookups{0};
  77   std::atomic<uint64_t> d_deferredInserts{0};
  78   std::atomic<uint64_t> d_hits{0};
  79   std::atomic<uint64_t> d_misses{0};
  80   std::atomic<uint64_t> d_insertCollisions{0};
  81   std::atomic<uint64_t> d_lookupCollisions{0};
  82   std::atomic<uint64_t> d_ttlTooShorts{0};
  83   size_t d_maxEntries;
  84   uint32_t d_maxTTL;
  85   uint32_t d_tempFailureTTL;
  86   uint32_t d_minTTL;
  87   uint32_t d_staleTTL;
  88 };