pdns/auth-packetcache.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 #ifndef AUTH_PACKETCACHE_HH
  23 #define AUTH_PACKETCACHE_HH
  24
  25 #include <string>
  26 #include <map>
  27 #include "dns.hh"
  28 #include <boost/version.hpp>
  29 #include "namespaces.hh"
  30 using namespace ::boost::multi_index;
  31
  32 #include <boost/multi_index/hashed_index.hpp>
  33
  34 #include "dnspacket.hh"
  35 #include "lock.hh"
  36 #include "packetcache.hh"
  37
  38 /** This class performs 'whole packet caching'. Feed it a question packet and it will
  39     try to find an answer. If you have an answer, insert it to have it cached for later use.
  40     Take care not to replace existing cache entries. While this works, it is wasteful. Only
  41     insert packets that where not found by get()
  42
  43     Locking!
  44
  45     The cache itself is protected by a read/write lock. Because deleting is a two step process, which
  46     first marks and then sweeps, a second lock is present to prevent simultaneous inserts and deletes.
  47 */
  48
  49 class AuthPacketCache : public PacketCache
  50 {
  51 public:
  52   AuthPacketCache(size_t mapsCount=1024);
  53   ~AuthPacketCache();
  54
  55   void insert(DNSPacket *q, DNSPacket *r, uint32_t maxTTL);  //!< We copy the contents of *p into our cache. Do not needlessly call this to insert questions already in the cache as it wastes resources
  56
  57   bool get(DNSPacket *p, DNSPacket *q); //!< We return a dynamically allocated copy out of our cache. You need to delete it. You also need to spoof in the right ID with the DNSPacket.spoofID() method.
  58
  59   void cleanup(); //!< force the cache to preen itself from expired packets
  60   uint64_t purge();
  61   uint64_t purge(const std::string& match); // could be $ terminated. Is not a dnsname!
  62   uint64_t purgeExact(const DNSName& qname); // no wildcard matching here
  63
  64   uint64_t size() const { return *d_statnumentries; };
  65
  66   void setMaxEntries(uint64_t maxEntries)
  67   {
  68     d_maxEntries = maxEntries;
  69   }
  70   void setTTL(uint32_t ttl)
  71   {
  72     d_ttl = ttl;
  73   }
  74   bool enabled()
  75   {
  76     return (d_ttl > 0);
  77   }
  78 private:
  79
  80   struct CacheEntry
  81   {
  82     mutable string query;
  83     mutable string value;
  84     DNSName qname;
  85
  86     mutable time_t created{0};
  87     mutable time_t ttd{0};
  88     uint32_t hash{0};
  89     uint16_t qtype{0};
  90     bool tcp{false};
  91   };
  92
  93   struct HashTag{};
  94   struct NameTag{};
  95   struct SequenceTag{};
  96   typedef multi_index_container<
  97     CacheEntry,
  98     indexed_by <
  99       hashed_non_unique<tag<HashTag>, member<CacheEntry,uint32_t,&CacheEntry::hash> >,
 100       ordered_non_unique<tag<NameTag>, member<CacheEntry,DNSName,&CacheEntry::qname>, CanonDNSNameCompare >,
 101       sequenced<tag<SequenceTag>>
 102       >
 103     > cmap_t;
 104
 105   struct MapCombo
 106   {
 107     pthread_rwlock_t d_mut;
 108     cmap_t d_map;
 109   };
 110
 111   vector<MapCombo> d_maps;
 112   MapCombo& getMap(const DNSName& name)
 113   {
 114     return d_maps[name.hash() % d_maps.size()];
 115   }
 116
 117   static bool entryMatches(cmap_t::index<HashTag>::type::iterator& iter, const std::string& query, const DNSName& qname, uint16_t qtype, bool tcp);
 118   bool getEntryLocked(cmap_t& map, const std::string& query, uint32_t hash, const DNSName &qname, uint16_t qtype, bool tcp, time_t now, string& entry);
 119   void cleanupIfNeeded();
 120
 121   AtomicCounter d_ops{0};
 122   AtomicCounter *d_statnumhit;
 123   AtomicCounter *d_statnummiss;
 124   AtomicCounter *d_statnumentries;
 125
 126   uint64_t d_maxEntries{0};
 127   time_t d_lastclean; // doesn't need to be atomic
 128   unsigned long d_nextclean{4096};
 129   unsigned int d_cleaninterval{4096};
 130   uint32_t d_ttl{0};
 131   bool d_cleanskipped{false};
 132
 133   static const unsigned int s_mincleaninterval=1000, s_maxcleaninterval=300000;
 134 };
 135
 136 #endif /* AUTH_PACKETCACHE_HH */