a9da14e1e9
For each transaction, record when the earliest point in time when the query packet may hit the wire. This is the same time stamp for which the timer is scheduled in retries, except for the initial query packets which are delayed by a random jitter. In this case, we denote that the packet may actually be sent at the nominal time, without the jitter. Transactions that share the same timestamp will also have identical values in this field. It is used to coalesce pending queries in a later patch.
135 lines
4.3 KiB
C
135 lines
4.3 KiB
C
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
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#pragma once
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/***
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This file is part of systemd.
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Copyright 2014 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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typedef struct DnsTransaction DnsTransaction;
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typedef enum DnsTransactionState DnsTransactionState;
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typedef enum DnsTransactionSource DnsTransactionSource;
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enum DnsTransactionState {
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DNS_TRANSACTION_NULL,
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DNS_TRANSACTION_PENDING,
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DNS_TRANSACTION_FAILURE,
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DNS_TRANSACTION_SUCCESS,
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DNS_TRANSACTION_NO_SERVERS,
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DNS_TRANSACTION_TIMEOUT,
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DNS_TRANSACTION_ATTEMPTS_MAX_REACHED,
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DNS_TRANSACTION_INVALID_REPLY,
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DNS_TRANSACTION_RESOURCES,
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DNS_TRANSACTION_ABORTED,
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_DNS_TRANSACTION_STATE_MAX,
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_DNS_TRANSACTION_STATE_INVALID = -1
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};
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enum DnsTransactionSource {
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DNS_TRANSACTION_NETWORK,
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DNS_TRANSACTION_CACHE,
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DNS_TRANSACTION_ZONE,
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DNS_TRANSACTION_TRUST_ANCHOR,
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_DNS_TRANSACTION_SOURCE_MAX,
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_DNS_TRANSACTION_SOURCE_INVALID = -1
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};
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#include "resolved-dns-answer.h"
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#include "resolved-dns-packet.h"
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#include "resolved-dns-question.h"
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#include "resolved-dns-scope.h"
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struct DnsTransaction {
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DnsScope *scope;
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DnsResourceKey *key;
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DnsTransactionState state;
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uint16_t id;
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bool initial_jitter_scheduled;
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bool initial_jitter_elapsed;
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DnsPacket *sent, *received;
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DnsAnswer *answer;
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int answer_rcode;
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DnsTransactionSource answer_source;
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bool answer_authenticated;
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usec_t start_usec;
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usec_t next_attempt_after;
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sd_event_source *timeout_event_source;
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unsigned n_attempts;
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int dns_udp_fd;
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sd_event_source *dns_udp_event_source;
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/* The active server */
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DnsServer *server;
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/* the features of the DNS server at time of transaction start */
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DnsServerFeatureLevel current_features;
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/* TCP connection logic, if we need it */
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DnsStream *stream;
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/* Query candidates this transaction is referenced by and that
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* shall be notified about this specific transaction
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* completing. */
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Set *query_candidates;
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/* Zone items this transaction is referenced by and that shall
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* be notified about completion. */
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Set *zone_items;
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unsigned block_gc;
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LIST_FIELDS(DnsTransaction, transactions_by_scope);
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};
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int dns_transaction_new(DnsTransaction **ret, DnsScope *s, DnsResourceKey *key);
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DnsTransaction* dns_transaction_free(DnsTransaction *t);
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void dns_transaction_gc(DnsTransaction *t);
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int dns_transaction_go(DnsTransaction *t);
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void dns_transaction_process_reply(DnsTransaction *t, DnsPacket *p);
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void dns_transaction_complete(DnsTransaction *t, DnsTransactionState state);
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const char* dns_transaction_state_to_string(DnsTransactionState p) _const_;
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DnsTransactionState dns_transaction_state_from_string(const char *s) _pure_;
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const char* dns_transaction_source_to_string(DnsTransactionSource p) _const_;
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DnsTransactionSource dns_transaction_source_from_string(const char *s) _pure_;
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/* LLMNR Jitter interval, see RFC 4795 Section 7 */
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#define LLMNR_JITTER_INTERVAL_USEC (100 * USEC_PER_MSEC)
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/* mDNS Jitter interval, see RFC 6762 Section 5.2 */
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#define MDNS_JITTER_MIN_USEC (20 * USEC_PER_MSEC)
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#define MDNS_JITTER_RANGE_USEC (100 * USEC_PER_MSEC)
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/* Maximum attempts to send DNS requests, across all DNS servers */
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#define DNS_TRANSACTION_ATTEMPTS_MAX 16
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/* Maximum attempts to send LLMNR requests, see RFC 4795 Section 2.7 */
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#define LLMNR_TRANSACTION_ATTEMPTS_MAX 3
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#define TRANSACTION_ATTEMPTS_MAX(p) ((p) == DNS_PROTOCOL_LLMNR ? LLMNR_TRANSACTION_ATTEMPTS_MAX : DNS_TRANSACTION_ATTEMPTS_MAX)
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