developer.intra2net.com Git - pingcheck/blob - src/dns/dnsresolver.h

   1 /*
   2  The software in this package is distributed under the GNU General
   3  Public License version 2 (with a special exception described below).
   4
   5  A copy of GNU General Public License (GPL) is included in this distribution,
   6  in the file COPYING.GPL.
   7
   8  As a special exception, if other files instantiate templates or use macros
   9  or inline functions from this file, or you compile this file and link it
  10  with other works to produce a work based on this file, this file
  11  does not by itself cause the resulting work to be covered
  12  by the GNU General Public License.
  13
  14  However the source code for this file must still be made available
  15  in accordance with section (3) of the GNU General Public License.
  16
  17  This exception does not invalidate any other reasons why a work based
  18  on this file might be covered by the GNU General Public License.
  19
  20  Christian Herdtweck, Intra2net AG 2015
  21  */
  22
  23 #ifndef DNS_RESOLVER_H
  24 #define DNS_RESOLVER_H
  25
  26 #include "dns/dnsmaster.h"
  27
  28 #include <boost/asio/deadline_timer.hpp>
  29 #include <boost/asio/ip/udp.hpp>
  30 #include <boost/asio/ip/address.hpp>
  31 #include <boost/system/error_code.hpp>
  32 #include <boost/net/network_array.hpp>   // dns_buffer_t
  33 #include <boost/uuid/uuid_generators.hpp>
  34
  35 #include "dns/resolverbase.h"
  36 #include "dns/dnsmaster.h"
  37 #include "dns/dnscache.h"
  38
  39
  40 typedef std::pair<std::string, std::string> string_pair;
  41 typedef std::pair<std::string, Cname> src_cname_pair;
  42 typedef std::pair<std::string, HostAddress> host_addr_pair;
  43
  44
  45 class DnsResolver : public ResolverBase
  46 {
  47 public:
  48     ~DnsResolver();
  49
  50 // constructor accessible from friend DnsMaster
  51 public:
  52     friend ResolverItem& DnsMaster::get_resolver_for(
  53                                                  const std::string &hostname,
  54                                                  const DnsIpProtocol &protocol);
  55     friend ResolverItem DnsMaster::get_recursor_for(
  56                                    const std::string &hostname,
  57                                    const DnsIpProtocol &protocol,
  58                                    const boost::asio::ip::address &name_server);
  59 private:
  60     DnsResolver(IoServiceItem &io_serv,
  61                 const std::string &hostname,
  62                 const DnsIpProtocol &protocol,
  63                 const DnsCacheItem cache,
  64                 const boost::asio::ip::address &name_server);
  65
  66 // only real public function (called from pingers)
  67 public:
  68     HostAddress get_next_ip();
  69     bool have_up_to_date_ip();
  70     int get_resolved_ip_count();
  71     void cancel_resolve();
  72     bool is_resolving();
  73
  74 // implementation of ResolverBase::async_resolve
  75 protected:
  76     void do_resolve();
  77
  78 // internal helper functions
  79 private:
  80     void handle_resolve_timeout(const boost::system::error_code &error);
  81     void handle_dns_result(const boost::system::error_code &error,
  82                            const std::size_t bytes_transferred);
  83     void handle_unavailable();
  84     void handle_ips(const std::vector<host_addr_pair> &result_ips);
  85     void handle_cname(const std::vector<src_cname_pair> &result_cnames);
  86     void handle_recurse(const HostAddress &name_server);
  87     void handle_recurse_without_ip(const std::string &name_server);
  88     void cname_resolve_callback(const bool was_success,
  89                                 const int recursion_count);
  90     void recursive_resolve_callback(const uint32_t min_ttl,
  91                                     const bool was_success,
  92                                     const int recursion_count);
  93     void name_server_resolve_callback(const bool was_success,
  94                                       const int recursion_count);
  95     void schedule_retry();
  96     void finalize_resolve(const bool success, const int recursion_count=0);
  97     void stop_trying();
  98     void wait_timer_timeout_handler(const boost::system::error_code &error);
  99     void gather_results( const boost::net::dns::rr_list_t *answers,
 100                          std::vector<host_addr_pair> *result_ips,
 101                          std::vector<src_cname_pair> *result_cnames,
 102                          std::vector<string_pair> *result_nameservers ) const;
 103
 104 // variables
 105 private:
 106     boost::asio::ip::udp::socket Socket;
 107     boost::net::dns_buffer_t ReceiveBuffer;
 108     boost::net::dns_buffer_t RequestBuffer;
 109     DnsIpProtocol Protocol;
 110     boost::asio::ip::udp::endpoint NameServer;
 111     boost::asio::deadline_timer ResolveTimeoutTimer;
 112     boost::asio::deadline_timer PauseBeforeRetryTimer;
 113     boost::asio::deadline_timer StaleDataLongtermTimer;
 114     std::size_t NextIpIndex;
 115     int RetryCount;
 116     bool IsResolving;
 117     std::string LogPrefix;
 118     boost::uuids::random_generator RandomIdGenerator;
 119     uint16_t RequestId;
 120     ResolverItem Recursor;
 121     bool OperationCancelled;
 122 };
 123
 124 #endif
 125 // (created using vim -- the world's best text editor)
 126