/*** This file is part of systemd. Copyright 2014 Lennart Poettering systemd is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. systemd is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with systemd; If not, see . ***/ #include "alloc-util.h" #include "dns-domain.h" #include "dns-type.h" #include "hostname-util.h" #include "local-addresses.h" #include "resolved-dns-query.h" #include "resolved-dns-synthesize.h" #include "resolved-etc-hosts.h" #include "string-util.h" /* How long to wait for the query in total */ #define QUERY_TIMEOUT_USEC (30 * USEC_PER_SEC) #define CNAME_MAX 8 #define QUERIES_MAX 2048 #define AUXILIARY_QUERIES_MAX 64 static int dns_query_candidate_new(DnsQueryCandidate **ret, DnsQuery *q, DnsScope *s) { DnsQueryCandidate *c; assert(ret); assert(q); assert(s); c = new0(DnsQueryCandidate, 1); if (!c) return -ENOMEM; c->query = q; c->scope = s; LIST_PREPEND(candidates_by_query, q->candidates, c); LIST_PREPEND(candidates_by_scope, s->query_candidates, c); *ret = c; return 0; } static void dns_query_candidate_stop(DnsQueryCandidate *c) { DnsTransaction *t; assert(c); while ((t = set_steal_first(c->transactions))) { set_remove(t->notify_query_candidates, c); set_remove(t->notify_query_candidates_done, c); dns_transaction_gc(t); } } DnsQueryCandidate* dns_query_candidate_free(DnsQueryCandidate *c) { if (!c) return NULL; dns_query_candidate_stop(c); set_free(c->transactions); dns_search_domain_unref(c->search_domain); if (c->query) LIST_REMOVE(candidates_by_query, c->query->candidates, c); if (c->scope) LIST_REMOVE(candidates_by_scope, c->scope->query_candidates, c); free(c); return NULL; } static int dns_query_candidate_next_search_domain(DnsQueryCandidate *c) { DnsSearchDomain *next = NULL; assert(c); if (c->search_domain && c->search_domain->linked) next = c->search_domain->domains_next; else next = dns_scope_get_search_domains(c->scope); for (;;) { if (!next) /* We hit the end of the list */ return 0; if (!next->route_only) break; /* Skip over route-only domains */ next = next->domains_next; } dns_search_domain_unref(c->search_domain); c->search_domain = dns_search_domain_ref(next); return 1; } static int dns_query_candidate_add_transaction(DnsQueryCandidate *c, DnsResourceKey *key) { DnsTransaction *t; int r; assert(c); assert(key); t = dns_scope_find_transaction(c->scope, key, true); if (!t) { r = dns_transaction_new(&t, c->scope, key); if (r < 0) return r; } else { if (set_contains(c->transactions, t)) return 0; } r = set_ensure_allocated(&c->transactions, NULL); if (r < 0) goto gc; r = set_ensure_allocated(&t->notify_query_candidates, NULL); if (r < 0) goto gc; r = set_ensure_allocated(&t->notify_query_candidates_done, NULL); if (r < 0) goto gc; r = set_put(t->notify_query_candidates, c); if (r < 0) goto gc; r = set_put(c->transactions, t); if (r < 0) { (void) set_remove(t->notify_query_candidates, c); goto gc; } t->clamp_ttl = c->query->clamp_ttl; return 1; gc: dns_transaction_gc(t); return r; } static int dns_query_candidate_go(DnsQueryCandidate *c) { DnsTransaction *t; Iterator i; int r; unsigned n = 0; assert(c); /* Start the transactions that are not started yet */ SET_FOREACH(t, c->transactions, i) { if (t->state != DNS_TRANSACTION_NULL) continue; r = dns_transaction_go(t); if (r < 0) return r; n++; } /* If there was nothing to start, then let's proceed immediately */ if (n == 0) dns_query_candidate_notify(c); return 0; } static DnsTransactionState dns_query_candidate_state(DnsQueryCandidate *c) { DnsTransactionState state = DNS_TRANSACTION_NO_SERVERS; DnsTransaction *t; Iterator i; assert(c); if (c->error_code != 0) return DNS_TRANSACTION_ERRNO; SET_FOREACH(t, c->transactions, i) { switch (t->state) { case DNS_TRANSACTION_NULL: /* If there's a NULL transaction pending, then * this means not all transactions where * started yet, and we were called from within * the stackframe that is supposed to start * remaining transactions. In this case, * simply claim the candidate is pending. */ case DNS_TRANSACTION_PENDING: case DNS_TRANSACTION_VALIDATING: /* If there's one transaction currently in * VALIDATING state, then this means there's * also one in PENDING state, hence we can * return PENDING immediately. */ return DNS_TRANSACTION_PENDING; case DNS_TRANSACTION_SUCCESS: state = t->state; break; default: if (state != DNS_TRANSACTION_SUCCESS) state = t->state; break; } } return state; } static bool dns_query_candidate_is_routable(DnsQueryCandidate *c, uint16_t type) { int family; assert(c); /* Checks whether the specified RR type matches an address family that is routable on the link(s) the scope of * this candidate belongs to. Specifically, whether there's a routable IPv4 address on it if we query an A RR, * or a routable IPv6 address if we query an AAAA RR. */ if (!c->query->suppress_unroutable_family) return true; if (c->scope->protocol != DNS_PROTOCOL_DNS) return true; family = dns_type_to_af(type); if (family < 0) return true; if (c->scope->link) return link_relevant(c->scope->link, family, false); else return manager_routable(c->scope->manager, family); } static int dns_query_candidate_setup_transactions(DnsQueryCandidate *c) { DnsQuestion *question; DnsResourceKey *key; int n = 0, r; assert(c); dns_query_candidate_stop(c); question = dns_query_question_for_protocol(c->query, c->scope->protocol); /* Create one transaction per question key */ DNS_QUESTION_FOREACH(key, question) { _cleanup_(dns_resource_key_unrefp) DnsResourceKey *new_key = NULL; DnsResourceKey *qkey; if (!dns_query_candidate_is_routable(c, key->type)) continue; if (c->search_domain) { r = dns_resource_key_new_append_suffix(&new_key, key, c->search_domain->name); if (r < 0) goto fail; qkey = new_key; } else qkey = key; if (!dns_scope_good_key(c->scope, qkey)) continue; r = dns_query_candidate_add_transaction(c, qkey); if (r < 0) goto fail; n++; } return n; fail: dns_query_candidate_stop(c); return r; } void dns_query_candidate_notify(DnsQueryCandidate *c) { DnsTransactionState state; int r; assert(c); state = dns_query_candidate_state(c); if (DNS_TRANSACTION_IS_LIVE(state)) return; if (state != DNS_TRANSACTION_SUCCESS && c->search_domain) { r = dns_query_candidate_next_search_domain(c); if (r < 0) goto fail; if (r > 0) { /* OK, there's another search domain to try, let's do so. */ r = dns_query_candidate_setup_transactions(c); if (r < 0) goto fail; if (r > 0) { /* New transactions where queued. Start them and wait */ r = dns_query_candidate_go(c); if (r < 0) goto fail; return; } } } dns_query_ready(c->query); return; fail: log_warning_errno(r, "Failed to follow search domains: %m"); c->error_code = r; dns_query_ready(c->query); } static void dns_query_stop(DnsQuery *q) { DnsQueryCandidate *c; assert(q); q->timeout_event_source = sd_event_source_unref(q->timeout_event_source); LIST_FOREACH(candidates_by_query, c, q->candidates) dns_query_candidate_stop(c); } static void dns_query_free_candidates(DnsQuery *q) { assert(q); while (q->candidates) dns_query_candidate_free(q->candidates); } static void dns_query_reset_answer(DnsQuery *q) { assert(q); q->answer = dns_answer_unref(q->answer); q->answer_rcode = 0; q->answer_dnssec_result = _DNSSEC_RESULT_INVALID; q->answer_errno = 0; q->answer_authenticated = false; q->answer_protocol = _DNS_PROTOCOL_INVALID; q->answer_family = AF_UNSPEC; q->answer_search_domain = dns_search_domain_unref(q->answer_search_domain); } DnsQuery *dns_query_free(DnsQuery *q) { if (!q) return NULL; while (q->auxiliary_queries) dns_query_free(q->auxiliary_queries); if (q->auxiliary_for) { assert(q->auxiliary_for->n_auxiliary_queries > 0); q->auxiliary_for->n_auxiliary_queries--; LIST_REMOVE(auxiliary_queries, q->auxiliary_for->auxiliary_queries, q); } dns_query_free_candidates(q); dns_question_unref(q->question_idna); dns_question_unref(q->question_utf8); dns_query_reset_answer(q); sd_bus_message_unref(q->request); sd_bus_track_unref(q->bus_track); dns_packet_unref(q->request_dns_packet); if (q->request_dns_stream) { /* Detach the stream from our query, in case something else keeps a reference to it. */ q->request_dns_stream->complete = NULL; q->request_dns_stream->on_packet = NULL; q->request_dns_stream->query = NULL; dns_stream_unref(q->request_dns_stream); } free(q->request_address_string); if (q->manager) { LIST_REMOVE(queries, q->manager->dns_queries, q); q->manager->n_dns_queries--; } free(q); return NULL; } int dns_query_new( Manager *m, DnsQuery **ret, DnsQuestion *question_utf8, DnsQuestion *question_idna, int ifindex, uint64_t flags) { _cleanup_(dns_query_freep) DnsQuery *q = NULL; DnsResourceKey *key; bool good = false; int r; char key_str[DNS_RESOURCE_KEY_STRING_MAX]; assert(m); if (dns_question_size(question_utf8) > 0) { r = dns_question_is_valid_for_query(question_utf8); if (r < 0) return r; if (r == 0) return -EINVAL; good = true; } /* If the IDNA and UTF8 questions are the same, merge their references */ r = dns_question_is_equal(question_idna, question_utf8); if (r < 0) return r; if (r > 0) question_idna = question_utf8; else { if (dns_question_size(question_idna) > 0) { r = dns_question_is_valid_for_query(question_idna); if (r < 0) return r; if (r == 0) return -EINVAL; good = true; } } if (!good) /* don't allow empty queries */ return -EINVAL; if (m->n_dns_queries >= QUERIES_MAX) return -EBUSY; q = new0(DnsQuery, 1); if (!q) return -ENOMEM; q->question_utf8 = dns_question_ref(question_utf8); q->question_idna = dns_question_ref(question_idna); q->ifindex = ifindex; q->flags = flags; q->answer_dnssec_result = _DNSSEC_RESULT_INVALID; q->answer_protocol = _DNS_PROTOCOL_INVALID; q->answer_family = AF_UNSPEC; /* First dump UTF8 question */ DNS_QUESTION_FOREACH(key, question_utf8) log_debug("Looking up RR for %s.", dns_resource_key_to_string(key, key_str, sizeof key_str)); /* And then dump the IDNA question, but only what hasn't been dumped already through the UTF8 question. */ DNS_QUESTION_FOREACH(key, question_idna) { r = dns_question_contains(question_utf8, key); if (r < 0) return r; if (r > 0) continue; log_debug("Looking up IDNA RR for %s.", dns_resource_key_to_string(key, key_str, sizeof key_str)); } LIST_PREPEND(queries, m->dns_queries, q); m->n_dns_queries++; q->manager = m; if (ret) *ret = q; q = NULL; return 0; } int dns_query_make_auxiliary(DnsQuery *q, DnsQuery *auxiliary_for) { assert(q); assert(auxiliary_for); /* Ensure that the query is not auxiliary yet, and * nothing else is auxiliary to it either */ assert(!q->auxiliary_for); assert(!q->auxiliary_queries); /* Ensure that the unit we shall be made auxiliary for isn't * auxiliary itself */ assert(!auxiliary_for->auxiliary_for); if (auxiliary_for->n_auxiliary_queries >= AUXILIARY_QUERIES_MAX) return -EAGAIN; LIST_PREPEND(auxiliary_queries, auxiliary_for->auxiliary_queries, q); q->auxiliary_for = auxiliary_for; auxiliary_for->n_auxiliary_queries++; return 0; } static void dns_query_complete(DnsQuery *q, DnsTransactionState state) { assert(q); assert(!DNS_TRANSACTION_IS_LIVE(state)); assert(DNS_TRANSACTION_IS_LIVE(q->state)); /* Note that this call might invalidate the query. Callers * should hence not attempt to access the query or transaction * after calling this function. */ q->state = state; dns_query_stop(q); if (q->complete) q->complete(q); } static int on_query_timeout(sd_event_source *s, usec_t usec, void *userdata) { DnsQuery *q = userdata; assert(s); assert(q); dns_query_complete(q, DNS_TRANSACTION_TIMEOUT); return 0; } static int dns_query_add_candidate(DnsQuery *q, DnsScope *s) { DnsQueryCandidate *c; int r; assert(q); assert(s); r = dns_query_candidate_new(&c, q, s); if (r < 0) return r; /* If this a single-label domain on DNS, we might append a suitable search domain first. */ if ((q->flags & SD_RESOLVED_NO_SEARCH) == 0) { r = dns_scope_name_needs_search_domain(s, dns_question_first_name(q->question_idna)); if (r < 0) goto fail; if (r > 0) { /* OK, we need a search domain now. Let's find one for this scope */ r = dns_query_candidate_next_search_domain(c); if (r <= 0) /* if there's no search domain, then we won't add any transaction. */ goto fail; } } r = dns_query_candidate_setup_transactions(c); if (r < 0) goto fail; return 0; fail: dns_query_candidate_free(c); return r; } static int dns_query_synthesize_reply(DnsQuery *q, DnsTransactionState *state) { _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL; int r; assert(q); assert(state); /* Tries to synthesize localhost RR replies (and others) where appropriate. Note that this is done *after* the * the normal lookup finished. The data from the network hence takes precedence over the data we * synthesize. (But note that many scopes refuse to resolve certain domain names) */ if (!IN_SET(*state, DNS_TRANSACTION_RCODE_FAILURE, DNS_TRANSACTION_NO_SERVERS, DNS_TRANSACTION_TIMEOUT, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED, DNS_TRANSACTION_NETWORK_DOWN, DNS_TRANSACTION_NOT_FOUND)) return 0; r = dns_synthesize_answer( q->manager, q->question_utf8, q->ifindex, &answer); if (r <= 0) return r; dns_query_reset_answer(q); q->answer = answer; answer = NULL; q->answer_rcode = DNS_RCODE_SUCCESS; q->answer_protocol = dns_synthesize_protocol(q->flags); q->answer_family = dns_synthesize_family(q->flags); q->answer_authenticated = true; *state = DNS_TRANSACTION_SUCCESS; return 1; } static int dns_query_try_etc_hosts(DnsQuery *q) { _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL; int r; assert(q); /* Looks in /etc/hosts for matching entries. Note that this is done *before* the normal lookup is done. The * data from /etc/hosts hence takes precedence over the network. */ r = manager_etc_hosts_lookup( q->manager, q->question_utf8, &answer); if (r <= 0) return r; dns_query_reset_answer(q); q->answer = answer; answer = NULL; q->answer_rcode = DNS_RCODE_SUCCESS; q->answer_protocol = dns_synthesize_protocol(q->flags); q->answer_family = dns_synthesize_family(q->flags); q->answer_authenticated = true; return 1; } int dns_query_go(DnsQuery *q) { DnsScopeMatch found = DNS_SCOPE_NO; DnsScope *s, *first = NULL; DnsQueryCandidate *c; int r; assert(q); if (q->state != DNS_TRANSACTION_NULL) return 0; r = dns_query_try_etc_hosts(q); if (r < 0) return r; if (r > 0) { dns_query_complete(q, DNS_TRANSACTION_SUCCESS); return 1; } LIST_FOREACH(scopes, s, q->manager->dns_scopes) { DnsScopeMatch match; const char *name; name = dns_question_first_name(dns_query_question_for_protocol(q, s->protocol)); if (!name) continue; match = dns_scope_good_domain(s, q->ifindex, q->flags, name); if (match < 0) return match; if (match == DNS_SCOPE_NO) continue; found = match; if (match == DNS_SCOPE_YES) { first = s; break; } else { assert(match == DNS_SCOPE_MAYBE); if (!first) first = s; } } if (found == DNS_SCOPE_NO) { DnsTransactionState state = DNS_TRANSACTION_NO_SERVERS; r = dns_query_synthesize_reply(q, &state); if (r < 0) return r; dns_query_complete(q, state); return 1; } r = dns_query_add_candidate(q, first); if (r < 0) goto fail; LIST_FOREACH(scopes, s, first->scopes_next) { DnsScopeMatch match; const char *name; name = dns_question_first_name(dns_query_question_for_protocol(q, s->protocol)); if (!name) continue; match = dns_scope_good_domain(s, q->ifindex, q->flags, name); if (match < 0) goto fail; if (match != found) continue; r = dns_query_add_candidate(q, s); if (r < 0) goto fail; } dns_query_reset_answer(q); r = sd_event_add_time( q->manager->event, &q->timeout_event_source, clock_boottime_or_monotonic(), now(clock_boottime_or_monotonic()) + QUERY_TIMEOUT_USEC, 0, on_query_timeout, q); if (r < 0) goto fail; (void) sd_event_source_set_description(q->timeout_event_source, "query-timeout"); q->state = DNS_TRANSACTION_PENDING; q->block_ready++; /* Start the transactions */ LIST_FOREACH(candidates_by_query, c, q->candidates) { r = dns_query_candidate_go(c); if (r < 0) { q->block_ready--; goto fail; } } q->block_ready--; dns_query_ready(q); return 1; fail: dns_query_stop(q); return r; } static void dns_query_accept(DnsQuery *q, DnsQueryCandidate *c) { DnsTransactionState state = DNS_TRANSACTION_NO_SERVERS; bool has_authenticated = false, has_non_authenticated = false; DnssecResult dnssec_result_authenticated = _DNSSEC_RESULT_INVALID, dnssec_result_non_authenticated = _DNSSEC_RESULT_INVALID; DnsTransaction *t; Iterator i; int r; assert(q); if (!c) { r = dns_query_synthesize_reply(q, &state); if (r < 0) goto fail; dns_query_complete(q, state); return; } if (c->error_code != 0) { /* If the candidate had an error condition of its own, start with that. */ state = DNS_TRANSACTION_ERRNO; q->answer = dns_answer_unref(q->answer); q->answer_rcode = 0; q->answer_dnssec_result = _DNSSEC_RESULT_INVALID; q->answer_errno = c->error_code; } SET_FOREACH(t, c->transactions, i) { switch (t->state) { case DNS_TRANSACTION_SUCCESS: { /* We found a successfully reply, merge it into the answer */ r = dns_answer_extend(&q->answer, t->answer); if (r < 0) goto fail; q->answer_rcode = t->answer_rcode; q->answer_errno = 0; if (t->answer_authenticated) { has_authenticated = true; dnssec_result_authenticated = t->answer_dnssec_result; } else { has_non_authenticated = true; dnssec_result_non_authenticated = t->answer_dnssec_result; } state = DNS_TRANSACTION_SUCCESS; break; } case DNS_TRANSACTION_NULL: case DNS_TRANSACTION_PENDING: case DNS_TRANSACTION_VALIDATING: case DNS_TRANSACTION_ABORTED: /* Ignore transactions that didn't complete */ continue; default: /* Any kind of failure? Store the data away, * if there's nothing stored yet. */ if (state == DNS_TRANSACTION_SUCCESS) continue; q->answer = dns_answer_unref(q->answer); q->answer_rcode = t->answer_rcode; q->answer_dnssec_result = t->answer_dnssec_result; q->answer_errno = t->answer_errno; state = t->state; break; } } if (state == DNS_TRANSACTION_SUCCESS) { q->answer_authenticated = has_authenticated && !has_non_authenticated; q->answer_dnssec_result = q->answer_authenticated ? dnssec_result_authenticated : dnssec_result_non_authenticated; } q->answer_protocol = c->scope->protocol; q->answer_family = c->scope->family; dns_search_domain_unref(q->answer_search_domain); q->answer_search_domain = dns_search_domain_ref(c->search_domain); r = dns_query_synthesize_reply(q, &state); if (r < 0) goto fail; dns_query_complete(q, state); return; fail: q->answer_errno = -r; dns_query_complete(q, DNS_TRANSACTION_ERRNO); } void dns_query_ready(DnsQuery *q) { DnsQueryCandidate *bad = NULL, *c; bool pending = false; assert(q); assert(DNS_TRANSACTION_IS_LIVE(q->state)); /* Note that this call might invalidate the query. Callers * should hence not attempt to access the query or transaction * after calling this function, unless the block_ready * counter was explicitly bumped before doing so. */ if (q->block_ready > 0) return; LIST_FOREACH(candidates_by_query, c, q->candidates) { DnsTransactionState state; state = dns_query_candidate_state(c); switch (state) { case DNS_TRANSACTION_SUCCESS: /* One of the candidates is successful, * let's use it, and copy its data out */ dns_query_accept(q, c); return; case DNS_TRANSACTION_NULL: case DNS_TRANSACTION_PENDING: case DNS_TRANSACTION_VALIDATING: /* One of the candidates is still going on, * let's maybe wait for it */ pending = true; break; default: /* Any kind of failure */ bad = c; break; } } if (pending) return; dns_query_accept(q, bad); } static int dns_query_cname_redirect(DnsQuery *q, const DnsResourceRecord *cname) { _cleanup_(dns_question_unrefp) DnsQuestion *nq_idna = NULL, *nq_utf8 = NULL; int r, k; assert(q); q->n_cname_redirects++; if (q->n_cname_redirects > CNAME_MAX) return -ELOOP; r = dns_question_cname_redirect(q->question_idna, cname, &nq_idna); if (r < 0) return r; else if (r > 0) log_debug("Following CNAME/DNAME %s → %s.", dns_question_first_name(q->question_idna), dns_question_first_name(nq_idna)); k = dns_question_is_equal(q->question_idna, q->question_utf8); if (k < 0) return r; if (k > 0) { /* Same question? Shortcut new question generation */ nq_utf8 = dns_question_ref(nq_idna); k = r; } else { k = dns_question_cname_redirect(q->question_utf8, cname, &nq_utf8); if (k < 0) return k; else if (k > 0) log_debug("Following UTF8 CNAME/DNAME %s → %s.", dns_question_first_name(q->question_utf8), dns_question_first_name(nq_utf8)); } if (r == 0 && k == 0) /* No actual cname happened? */ return -ELOOP; if (q->answer_protocol == DNS_PROTOCOL_DNS) { /* Don't permit CNAME redirects from unicast DNS to LLMNR or MulticastDNS, so that global resources * cannot invade the local namespace. The opposite way we permit: local names may redirect to global * ones. */ q->flags &= ~(SD_RESOLVED_LLMNR|SD_RESOLVED_MDNS); /* mask away the local protocols */ } /* Turn off searching for the new name */ q->flags |= SD_RESOLVED_NO_SEARCH; dns_question_unref(q->question_idna); q->question_idna = nq_idna; nq_idna = NULL; dns_question_unref(q->question_utf8); q->question_utf8 = nq_utf8; nq_utf8 = NULL; dns_query_free_candidates(q); dns_query_reset_answer(q); q->state = DNS_TRANSACTION_NULL; return 0; } int dns_query_process_cname(DnsQuery *q) { _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *cname = NULL; DnsQuestion *question; DnsResourceRecord *rr; int r; assert(q); if (!IN_SET(q->state, DNS_TRANSACTION_SUCCESS, DNS_TRANSACTION_NULL)) return DNS_QUERY_NOMATCH; question = dns_query_question_for_protocol(q, q->answer_protocol); DNS_ANSWER_FOREACH(rr, q->answer) { r = dns_question_matches_rr(question, rr, DNS_SEARCH_DOMAIN_NAME(q->answer_search_domain)); if (r < 0) return r; if (r > 0) return DNS_QUERY_MATCH; /* The answer matches directly, no need to follow cnames */ r = dns_question_matches_cname_or_dname(question, rr, DNS_SEARCH_DOMAIN_NAME(q->answer_search_domain)); if (r < 0) return r; if (r > 0 && !cname) cname = dns_resource_record_ref(rr); } if (!cname) return DNS_QUERY_NOMATCH; /* No match and no cname to follow */ if (q->flags & SD_RESOLVED_NO_CNAME) return -ELOOP; /* OK, let's actually follow the CNAME */ r = dns_query_cname_redirect(q, cname); if (r < 0) return r; /* Let's see if the answer can already answer the new * redirected question */ r = dns_query_process_cname(q); if (r != DNS_QUERY_NOMATCH) return r; /* OK, it cannot, let's begin with the new query */ r = dns_query_go(q); if (r < 0) return r; return DNS_QUERY_RESTARTED; /* We restarted the query for a new cname */ } static int on_bus_track(sd_bus_track *t, void *userdata) { DnsQuery *q = userdata; assert(t); assert(q); log_debug("Client of active query vanished, aborting query."); dns_query_complete(q, DNS_TRANSACTION_ABORTED); return 0; } int dns_query_bus_track(DnsQuery *q, sd_bus_message *m) { int r; assert(q); assert(m); if (!q->bus_track) { r = sd_bus_track_new(sd_bus_message_get_bus(m), &q->bus_track, on_bus_track, q); if (r < 0) return r; } r = sd_bus_track_add_sender(q->bus_track, m); if (r < 0) return r; return 0; } DnsQuestion* dns_query_question_for_protocol(DnsQuery *q, DnsProtocol protocol) { assert(q); switch (protocol) { case DNS_PROTOCOL_DNS: return q->question_idna; case DNS_PROTOCOL_MDNS: case DNS_PROTOCOL_LLMNR: return q->question_utf8; default: return NULL; } } const char *dns_query_string(DnsQuery *q) { const char *name; int r; /* Returns a somewhat useful human-readable lookup key string for this query */ if (q->request_address_string) return q->request_address_string; if (q->request_address_valid) { r = in_addr_to_string(q->request_family, &q->request_address, &q->request_address_string); if (r >= 0) return q->request_address_string; } name = dns_question_first_name(q->question_utf8); if (name) return name; return dns_question_first_name(q->question_idna); }