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 cname_resolve_callback(const bool was_success,
  87                                 const int cname_count);
  88     void schedule_retry();
  89     void finalize_resolve(const bool success, const int cname_count=0);
  90     void stop_trying();
  91     void wait_timer_timeout_handler(const boost::system::error_code &error);
  92     void gather_results( const boost::net::dns::rr_list_t *rr_list,
  93                          std::vector<host_addr_pair> *result_ips,
  94                          std::vector<src_cname_pair> *result_cnames,
  95                          std::vector<string_pair> *result_nameservers ) const;
  96
  97 // variables
  98 private:
  99     boost::asio::ip::udp::socket Socket;
 100     boost::net::dns_buffer_t ReceiveBuffer;
 101     boost::net::dns_buffer_t RequestBuffer;
 102     DnsIpProtocol Protocol;
 103     boost::asio::ip::udp::endpoint NameServer;
 104     boost::asio::deadline_timer ResolveTimeoutTimer;
 105     boost::asio::deadline_timer PauseBeforeRetryTimer;
 106     boost::asio::deadline_timer StaleDataLongtermTimer;
 107     std::size_t NextIpIndex;
 108     int RetryCount;
 109     bool IsResolving;    // true from async_resolve until finalize_resolve;
 110                          // false e.g. while waiting for StaleDataLongtermTimer
 111     std::string LogPrefix;
 112     boost::uuids::random_generator RandomIdGenerator;
 113     uint16_t RequestId;
 114     bool OperationCancelled;
 115 };
 116
 117 #endif
 118 // (created using vim -- the world's best text editor)
 119