409 lines
11 KiB
C
409 lines
11 KiB
C
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/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
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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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#include "resolved-dns-query.h"
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#include "resolved-dns-domain.h"
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#define TRANSACTION_TIMEOUT_USEC (5 * USEC_PER_SEC)
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#define QUERY_TIMEOUT_USEC (30 * USEC_PER_SEC)
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#define ATTEMPTS_MAX 8
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DnsQueryTransaction* dns_query_transaction_free(DnsQueryTransaction *t) {
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if (!t)
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return NULL;
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sd_event_source_unref(t->timeout_event_source);
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dns_packet_unref(t->packet);
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if (t->query) {
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LIST_REMOVE(transactions_by_query, t->query->transactions, t);
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hashmap_remove(t->query->manager->dns_query_transactions, UINT_TO_PTR(t->id));
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}
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if (t->scope)
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LIST_REMOVE(transactions_by_scope, t->scope->transactions, t);
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free(t);
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return NULL;
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}
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DEFINE_TRIVIAL_CLEANUP_FUNC(DnsQueryTransaction*, dns_query_transaction_free);
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static int dns_query_transaction_new(DnsQuery *q, DnsQueryTransaction **ret, DnsScope *s) {
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_cleanup_(dns_query_transaction_freep) DnsQueryTransaction *t = NULL;
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int r;
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assert(q);
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assert(s);
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r = hashmap_ensure_allocated(&q->manager->dns_query_transactions, NULL, NULL);
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if (r < 0)
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return r;
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t = new0(DnsQueryTransaction, 1);
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if (!t)
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return -ENOMEM;
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do
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random_bytes(&t->id, sizeof(t->id));
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while (t->id == 0 ||
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hashmap_get(q->manager->dns_query_transactions, UINT_TO_PTR(t->id)));
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r = hashmap_put(q->manager->dns_query_transactions, UINT_TO_PTR(t->id), t);
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if (r < 0) {
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t->id = 0;
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return r;
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}
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LIST_PREPEND(transactions_by_query, q->transactions, t);
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t->query = q;
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LIST_PREPEND(transactions_by_scope, s->transactions, t);
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t->scope = s;
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if (ret)
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*ret = t;
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t = NULL;
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return 0;
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}
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static void dns_query_transaction_set_state(DnsQueryTransaction *t, DnsQueryState state) {
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assert(t);
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if (t->state == state)
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return;
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t->state = state;
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if (state != DNS_QUERY_SENT)
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t->timeout_event_source = sd_event_source_unref(t->timeout_event_source);
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dns_query_finish(t->query);
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}
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int dns_query_transaction_reply(DnsQueryTransaction *t, DnsPacket *p) {
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assert(t);
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assert(p);
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t->packet = dns_packet_ref(p);
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if (DNS_PACKET_RCODE(p) == DNS_RCODE_SUCCESS) {
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if( be16toh(DNS_PACKET_HEADER(p)->ancount) > 0)
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dns_query_transaction_set_state(t, DNS_QUERY_SUCCESS);
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else
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dns_query_transaction_set_state(t, DNS_QUERY_INVALID_REPLY);
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} else
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dns_query_transaction_set_state(t, DNS_QUERY_FAILURE);
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return 0;
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}
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static int on_transaction_timeout(sd_event_source *s, usec_t usec, void *userdata) {
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DnsQueryTransaction *t = userdata;
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int r;
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assert(s);
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assert(t);
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/* Timeout reached? Try again, with a new server */
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dns_scope_next_dns_server(t->scope);
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r = dns_query_transaction_start(t);
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if (r < 0)
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dns_query_transaction_set_state(t, DNS_QUERY_FAILURE);
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return 0;
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}
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int dns_query_transaction_start(DnsQueryTransaction *t) {
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_cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
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unsigned n;
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int r;
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assert(t);
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t->timeout_event_source = sd_event_source_unref(t->timeout_event_source);
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if (t->n_attempts >= ATTEMPTS_MAX) {
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dns_query_transaction_set_state(t, DNS_QUERY_ATTEMPTS_MAX);
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return 0;
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}
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t->n_attempts++;
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r = dns_packet_new_query(&p, 0);
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if (r < 0)
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return r;
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for (n = 0; n < t->query->n_keys; n++) {
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r = dns_packet_append_key(p, &t->query->keys[n], NULL);
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if (r < 0)
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return r;
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}
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DNS_PACKET_HEADER(p)->qdcount = htobe16(t->query->n_keys);
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DNS_PACKET_HEADER(p)->id = t->id;
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r = dns_scope_send(t->scope, p);
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if (r < 0) {
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/* Couldn't send? Try immediately again, with a new server */
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dns_scope_next_dns_server(t->scope);
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return dns_query_transaction_start(t);
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}
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if (r > 0) {
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int q;
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q = sd_event_add_time(t->query->manager->event, &t->timeout_event_source, CLOCK_MONOTONIC, now(CLOCK_MONOTONIC) + TRANSACTION_TIMEOUT_USEC, 0, on_transaction_timeout, t);
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if (q < 0)
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return q;
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dns_query_transaction_set_state(t, DNS_QUERY_SENT);
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} else
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dns_query_transaction_set_state(t, DNS_QUERY_SKIPPED);
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return r;
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}
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DnsQuery *dns_query_free(DnsQuery *q) {
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unsigned n;
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if (!q)
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return NULL;
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sd_bus_message_unref(q->request);
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dns_packet_unref(q->packet);
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sd_event_source_unref(q->timeout_event_source);
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while (q->transactions)
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dns_query_transaction_free(q->transactions);
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if (q->manager)
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LIST_REMOVE(queries, q->manager->dns_queries, q);
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for (n = 0; n < q->n_keys; n++)
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free(q->keys[n].name);
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free(q->keys);
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free(q);
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return NULL;
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}
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int dns_query_new(Manager *m, DnsQuery **ret, DnsResourceKey *keys, unsigned n_keys) {
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_cleanup_(dns_query_freep) DnsQuery *q = NULL;
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DnsScope *s, *first = NULL;
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DnsScopeMatch found = DNS_SCOPE_NO;
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const char *name = NULL;
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int n, r;
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assert(m);
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if (n_keys <= 0 || n_keys >= 65535)
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return -EINVAL;
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assert(keys);
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q = new0(DnsQuery, 1);
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if (!q)
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return -ENOMEM;
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q->keys = new(DnsResourceKey, n_keys);
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if (!q->keys)
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return -ENOMEM;
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for (q->n_keys = 0; q->n_keys < n_keys; q->n_keys++) {
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q->keys[q->n_keys].class = keys[q->n_keys].class;
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q->keys[q->n_keys].type = keys[q->n_keys].type;
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q->keys[q->n_keys].name = strdup(keys[q->n_keys].name);
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if (!q->keys[q->n_keys].name)
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return -ENOMEM;
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if (!name)
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name = q->keys[q->n_keys].name;
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else if (!dns_name_equal(name, q->keys[q->n_keys].name))
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return -EINVAL;
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}
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LIST_PREPEND(queries, m->dns_queries, q);
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q->manager = m;
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LIST_FOREACH(scopes, s, m->dns_scopes) {
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DnsScopeMatch match;
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match = dns_scope_test(s, name);
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if (match < 0)
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return match;
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if (match == DNS_SCOPE_NO)
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continue;
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found = match;
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if (match == DNS_SCOPE_YES) {
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first = s;
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break;
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} else {
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assert(match == DNS_SCOPE_MAYBE);
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if (!first)
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first = s;
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}
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}
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if (found == DNS_SCOPE_NO)
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return -ENETDOWN;
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r = dns_query_transaction_new(q, NULL, first);
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if (r < 0)
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return r;
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n = 1;
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LIST_FOREACH(scopes, s, first->scopes_next) {
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DnsScopeMatch match;
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match = dns_scope_test(s, name);
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if (match < 0)
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return match;
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if (match != found)
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continue;
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r = dns_query_transaction_new(q, NULL, s);
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if (r < 0)
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return r;
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n++;
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}
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if (ret)
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*ret = q;
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q = NULL;
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return n;
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}
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static void dns_query_set_state(DnsQuery *q, DnsQueryState state) {
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assert(q);
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if (q->state == state)
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return;
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q->state = state;
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if (state == DNS_QUERY_SENT)
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return;
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q->timeout_event_source = sd_event_source_unref(q->timeout_event_source);
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while (q->transactions)
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dns_query_transaction_free(q->transactions);
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if (q->complete)
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q->complete(q);
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}
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static int on_query_timeout(sd_event_source *s, usec_t usec, void *userdata) {
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DnsQuery *q = userdata;
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assert(s);
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assert(q);
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dns_query_set_state(q, DNS_QUERY_TIMEOUT);
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return 0;
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}
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int dns_query_start(DnsQuery *q) {
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DnsQueryTransaction *t;
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int r;
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assert(q);
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assert(q->state == DNS_QUERY_NULL);
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if (!q->transactions)
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return -ENETDOWN;
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r = sd_event_add_time(q->manager->event, &q->timeout_event_source, CLOCK_MONOTONIC, now(CLOCK_MONOTONIC) + QUERY_TIMEOUT_USEC, 0, on_query_timeout, q);
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if (r < 0)
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goto fail;
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dns_query_set_state(q, DNS_QUERY_SENT);
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LIST_FOREACH(transactions_by_query, t, q->transactions) {
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r = dns_query_transaction_start(t);
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if (r < 0)
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goto fail;
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if (q->state != DNS_QUERY_SENT)
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break;
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}
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return 0;
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fail:
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while (q->transactions)
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dns_query_transaction_free(q->transactions);
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return r;
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}
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void dns_query_finish(DnsQuery *q) {
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DnsQueryTransaction *t;
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DnsQueryState state = DNS_QUERY_SKIPPED;
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uint16_t rcode = 0;
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assert(q);
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if (q->state != DNS_QUERY_SENT)
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return;
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LIST_FOREACH(transactions_by_query, t, q->transactions) {
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/* One of the transactions is still going on, let's wait for it */
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if (t->state == DNS_QUERY_SENT || t->state == DNS_QUERY_NULL)
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return;
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/* One of the transactions is sucecssful, let's use it */
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if (t->state == DNS_QUERY_SUCCESS) {
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q->packet = dns_packet_ref(t->packet);
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dns_query_set_state(q, DNS_QUERY_SUCCESS);
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return;
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}
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if (t->state == DNS_QUERY_FAILURE) {
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state = DNS_QUERY_FAILURE;
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if (rcode == 0 && t->packet)
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rcode = DNS_PACKET_RCODE(t->packet);
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} else if (state == DNS_QUERY_SKIPPED && t->state != DNS_QUERY_SKIPPED)
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state = t->state;
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}
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if (state == DNS_QUERY_FAILURE)
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q->rcode = rcode;
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dns_query_set_state(q, state);
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}
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