src/resolve/resolved-dns-transaction.h

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 #pragma once
   4
   5 /***
   6   This file is part of systemd.
   7
   8   Copyright 2014 Lennart Poettering
   9
  10   systemd is free software; you can redistribute it and/or modify it
  11   under the terms of the GNU Lesser General Public License as published by
  12   the Free Software Foundation; either version 2.1 of the License, or
  13   (at your option) any later version.
  14
  15   systemd is distributed in the hope that it will be useful, but
  16   WITHOUT ANY WARRANTY; without even the implied warranty of
  17   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  18   Lesser General Public License for more details.
  19
  20   You should have received a copy of the GNU Lesser General Public License
  21   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  22 ***/
  23
  24 typedef struct DnsTransaction DnsTransaction;
  25 typedef enum DnsTransactionState DnsTransactionState;
  26
  27 enum DnsTransactionState {
  28         DNS_TRANSACTION_NULL,
  29         DNS_TRANSACTION_PENDING,
  30         DNS_TRANSACTION_FAILURE,
  31         DNS_TRANSACTION_SUCCESS,
  32         DNS_TRANSACTION_NO_SERVERS,
  33         DNS_TRANSACTION_TIMEOUT,
  34         DNS_TRANSACTION_ATTEMPTS_MAX_REACHED,
  35         DNS_TRANSACTION_INVALID_REPLY,
  36         DNS_TRANSACTION_RESOURCES,
  37         DNS_TRANSACTION_ABORTED,
  38         _DNS_TRANSACTION_STATE_MAX,
  39         _DNS_TRANSACTION_STATE_INVALID = -1
  40 };
  41
  42 #include "resolved-dns-answer.h"
  43 #include "resolved-dns-packet.h"
  44 #include "resolved-dns-question.h"
  45 #include "resolved-dns-scope.h"
  46
  47 struct DnsTransaction {
  48         DnsScope *scope;
  49
  50         DnsResourceKey *key;
  51
  52         DnsTransactionState state;
  53         uint16_t id;
  54
  55         bool initial_jitter;
  56
  57         DnsPacket *sent, *received;
  58         DnsAnswer *cached;
  59         int cached_rcode;
  60
  61         usec_t start_usec;
  62         sd_event_source *timeout_event_source;
  63         unsigned n_attempts;
  64
  65         int dns_udp_fd;
  66         sd_event_source *dns_udp_event_source;
  67
  68         /* The active server */
  69         DnsServer *server;
  70
  71         /* TCP connection logic, if we need it */
  72         DnsStream *stream;
  73
  74         /* Queries this transaction is referenced by and that shall be
  75          * notified about this specific transaction completing. */
  76         Set *queries;
  77
  78         /* Zone items this transaction is referenced by and that shall
  79          * be notified about completion. */
  80         Set *zone_items;
  81
  82         unsigned block_gc;
  83
  84         LIST_FIELDS(DnsTransaction, transactions_by_scope);
  85 };
  86
  87 int dns_transaction_new(DnsTransaction **ret, DnsScope *s, DnsResourceKey *key);
  88 DnsTransaction* dns_transaction_free(DnsTransaction *t);
  89
  90 void dns_transaction_gc(DnsTransaction *t);
  91 int dns_transaction_go(DnsTransaction *t);
  92
  93 void dns_transaction_process_reply(DnsTransaction *t, DnsPacket *p);
  94 void dns_transaction_complete(DnsTransaction *t, DnsTransactionState state);
  95
  96 const char* dns_transaction_state_to_string(DnsTransactionState p) _const_;
  97 DnsTransactionState dns_transaction_state_from_string(const char *s) _pure_;
  98
  99 /* LLMNR Jitter interval, see RFC 4795 Section 7 */
 100 #define LLMNR_JITTER_INTERVAL_USEC (100 * USEC_PER_MSEC)
 101
 102 /* Maximum attempts to send DNS requests, across all DNS servers */
 103 #define DNS_TRANSACTION_ATTEMPTS_MAX 16
 104
 105 /* Maximum attempts to send LLMNR requests, see RFC 4795 Section 2.7 */
 106 #define LLMNR_TRANSACTION_ATTEMPTS_MAX 3
 107
 108 #define TRANSACTION_ATTEMPTS_MAX(p) (p == DNS_PROTOCOL_LLMNR ? LLMNR_TRANSACTION_ATTEMPTS_MAX : DNS_TRANSACTION_ATTEMPTS_MAX)