ef7ce6df4d
When a jitter callback is issued instead of sending a DNS packet directly, on_transaction_timeout() is invoked to 'retry' the transaction. However, this function has side effects. For once, it increases the packet loss counter on the scope, and it also unrefs/refs the server instances. Fix this by tracking the jitter with two bool variables. One saying that the initial jitter has been scheduled in the first place, and one that tells us the delay packet has been sent.
134 lines
4.2 KiB
C
134 lines
4.2 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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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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