2 The software in this package is distributed under the GNU General
3 Public License version 2 (with a special exception described below).
5 A copy of GNU General Public License (GPL) is included in this distribution,
6 in the file COPYING.GPL.
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.
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.
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.
20 Christian Herdtweck, Intra2net AG 2015
23 #ifndef DNS_RESOLVER_H
24 #define DNS_RESOLVER_H
26 #include "dns/dnsmaster.h"
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>
35 #include "dns/resolverbase.h"
36 #include "dns/dnsmaster.h"
37 #include "dns/dnscache.h"
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;
45 class DnsResolver : public ResolverBase
50 // constructor accessible from friend DnsMaster
52 friend ResolverItem& DnsMaster::get_resolver_for(
53 const std::string &hostname,
54 const DnsIpProtocol &protocol);
56 DnsResolver(IoServiceItem &io_serv,
57 const std::string &hostname,
58 const DnsIpProtocol &protocol,
59 const DnsCacheItem cache,
60 const boost::asio::ip::address &name_server);
62 // only real public function (called from pingers)
64 HostAddress get_next_ip(const bool check_up_to_date=true);
65 bool have_up_to_date_ip();
66 int get_resolved_ip_count(const bool check_up_to_date=true);
67 void cancel_resolve();
68 bool is_resolving() const;
69 bool is_waiting_to_resolve() const;
71 // implementation of ResolverBase::async_resolve
73 void do_resolve(const int recursion_count);
75 // internal helper functions
77 void handle_resolve_timeout(const int recursion_count,
78 const boost::system::error_code &error);
79 void handle_dns_result(const int recursion_count,
80 const boost::system::error_code &error,
81 const std::size_t bytes_transferred);
82 void handle_unavailable(const int recursion_count);
83 void handle_ips(const int recursion_count,
84 const std::vector<host_addr_pair> &result_ips);
85 void handle_cname(const int recursion_count,
86 const std::vector<src_cname_pair> &result_cnames);
87 void cname_resolve_callback(const bool was_success,
88 const int recursion_count);
89 void schedule_retry(const int recursion_count);
90 void finalize_resolve(const bool success, const int recursion_count);
91 void stop_trying(const bool was_success);
92 void wait_timer_timeout_handler(const int recursion_count,
93 const boost::system::error_code &error);
94 void gather_results( const boost::net::dns::rr_list_t *rr_list,
95 std::vector<host_addr_pair> *result_ips,
96 std::vector<src_cname_pair> *result_cnames,
97 std::vector<string_pair> *result_nameservers ) const;
101 boost::asio::ip::udp::socket Socket;
102 boost::net::dns_buffer_t ReceiveBuffer;
103 boost::net::dns_buffer_t RequestBuffer;
104 boost::asio::ip::udp::endpoint NameServer;
105 boost::asio::deadline_timer ResolveTimeoutTimer;
106 boost::asio::deadline_timer PauseBeforeRetryTimer;
107 boost::asio::deadline_timer StaleDataLongtermTimer;
108 std::size_t NextIpIndex;
110 bool IsResolving; // true from async_resolve until finalize_resolve;
111 // false e.g. while waiting for StaleDataLongtermTimer
112 std::string LogPrefix;
113 boost::uuids::random_generator RandomIdGenerator;
115 bool OperationCancelled;
116 bool LongtermTimerIsActive;