/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ /*** 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 "hostname-util.h" #include "local-addresses.h" #include "resolved-dns-query.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); 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; if (!next) /* We hit the end of the list */ return 0; } else { next = dns_scope_get_search_domains(c->scope); if (!next) /* OK, there's nothing. */ return 0; } 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_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; } return 1; gc: dns_transaction_gc(t); return r; } static int dns_query_candidate_go(DnsQueryCandidate *c) { DnsTransaction *t; Iterator i; int r; 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; } 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_RESOURCES; 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 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; if (c->search_domain) { r = dns_resource_key_new_append_suffix(&new_key, key, c->search_domain->name); if (r < 0) goto fail; } r = dns_query_candidate_add_transaction(c, new_key ?: key); 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_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); 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; 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) { _cleanup_free_ char *p = NULL; r = dns_resource_key_to_string(key, &p); if (r < 0) return r; log_debug("Looking up RR for %s.", strstrip(p)); } /* And then dump the IDNA question, but only what hasn't been dumped already through the UTF8 question. */ DNS_QUESTION_FOREACH(key, question_idna) { _cleanup_free_ char *p = NULL; r = dns_question_contains(question_utf8, key); if (r < 0) return r; if (r > 0) continue; r = dns_resource_key_to_string(key, &p); if (r < 0) return r; log_debug("Looking up IDNA RR for %s.", strstrip(p)); } 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 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 SYNTHESIZE_IFINDEX(int ifindex) { /* When the caller asked for resolving on a specific * interface, we synthesize the answer for that * interface. However, if nothing specific was claimed and we * only return localhost RRs, we synthesize the answer for * localhost. */ if (ifindex > 0) return ifindex; return LOOPBACK_IFINDEX; } static int SYNTHESIZE_FAMILY(uint64_t flags) { /* Picks an address family depending on set flags. This is * purely for synthesized answers, where the family we return * for the reply should match what was requested in the * question, even though we are synthesizing the answer * here. */ if (!(flags & SD_RESOLVED_DNS)) { if (flags & SD_RESOLVED_LLMNR_IPV4) return AF_INET; if (flags & SD_RESOLVED_LLMNR_IPV6) return AF_INET6; } return AF_UNSPEC; } static DnsProtocol SYNTHESIZE_PROTOCOL(uint64_t flags) { /* Similar as SYNTHESIZE_FAMILY() but does this for the * protocol. If resolving via DNS was requested, we claim it * was DNS. Similar, if nothing specific was * requested. However, if only resolving via LLMNR was * requested we return that. */ if (flags & SD_RESOLVED_DNS) return DNS_PROTOCOL_DNS; if (flags & SD_RESOLVED_LLMNR) return DNS_PROTOCOL_LLMNR; return DNS_PROTOCOL_DNS; } static int dns_type_to_af(uint16_t t) { switch (t) { case DNS_TYPE_A: return AF_INET; case DNS_TYPE_AAAA: return AF_INET6; case DNS_TYPE_ANY: return AF_UNSPEC; default: return -EINVAL; } } static int synthesize_localhost_rr(DnsQuery *q, const DnsResourceKey *key, DnsAnswer **answer) { int r; assert(q); assert(key); assert(answer); r = dns_answer_reserve(answer, 2); if (r < 0) return r; if (IN_SET(key->type, DNS_TYPE_A, DNS_TYPE_ANY)) { _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL; rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_A, DNS_RESOURCE_KEY_NAME(key)); if (!rr) return -ENOMEM; rr->a.in_addr.s_addr = htobe32(INADDR_LOOPBACK); r = dns_answer_add(*answer, rr, SYNTHESIZE_IFINDEX(q->ifindex), DNS_ANSWER_AUTHENTICATED); if (r < 0) return r; } if (IN_SET(key->type, DNS_TYPE_AAAA, DNS_TYPE_ANY)) { _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL; rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_AAAA, DNS_RESOURCE_KEY_NAME(key)); if (!rr) return -ENOMEM; rr->aaaa.in6_addr = in6addr_loopback; r = dns_answer_add(*answer, rr, SYNTHESIZE_IFINDEX(q->ifindex), DNS_ANSWER_AUTHENTICATED); if (r < 0) return r; } return 0; } static int answer_add_ptr(DnsAnswer **answer, const char *from, const char *to, int ifindex, DnsAnswerFlags flags) { _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL; rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_PTR, from); if (!rr) return -ENOMEM; rr->ptr.name = strdup(to); if (!rr->ptr.name) return -ENOMEM; return dns_answer_add(*answer, rr, ifindex, flags); } static int synthesize_localhost_ptr(DnsQuery *q, const DnsResourceKey *key, DnsAnswer **answer) { int r; assert(q); assert(key); assert(answer); if (IN_SET(key->type, DNS_TYPE_PTR, DNS_TYPE_ANY)) { r = dns_answer_reserve(answer, 1); if (r < 0) return r; r = answer_add_ptr(answer, DNS_RESOURCE_KEY_NAME(key), "localhost", SYNTHESIZE_IFINDEX(q->ifindex), DNS_ANSWER_AUTHENTICATED); if (r < 0) return r; } return 0; } static int answer_add_addresses_rr( DnsAnswer **answer, const char *name, struct local_address *addresses, unsigned n_addresses) { unsigned j; int r; assert(answer); assert(name); r = dns_answer_reserve(answer, n_addresses); if (r < 0) return r; for (j = 0; j < n_addresses; j++) { _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL; r = dns_resource_record_new_address(&rr, addresses[j].family, &addresses[j].address, name); if (r < 0) return r; r = dns_answer_add(*answer, rr, addresses[j].ifindex, DNS_ANSWER_AUTHENTICATED); if (r < 0) return r; } return 0; } static int answer_add_addresses_ptr( DnsAnswer **answer, const char *name, struct local_address *addresses, unsigned n_addresses, int af, const union in_addr_union *match) { unsigned j; int r; assert(answer); assert(name); for (j = 0; j < n_addresses; j++) { _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL; if (af != AF_UNSPEC) { if (addresses[j].family != af) continue; if (match && !in_addr_equal(af, match, &addresses[j].address)) continue; } r = dns_answer_reserve(answer, 1); if (r < 0) return r; r = dns_resource_record_new_reverse(&rr, addresses[j].family, &addresses[j].address, name); if (r < 0) return r; r = dns_answer_add(*answer, rr, addresses[j].ifindex, DNS_ANSWER_AUTHENTICATED); if (r < 0) return r; } return 0; } static int synthesize_system_hostname_rr(DnsQuery *q, const DnsResourceKey *key, DnsAnswer **answer) { _cleanup_free_ struct local_address *addresses = NULL; int n = 0, af; assert(q); assert(key); assert(answer); af = dns_type_to_af(key->type); if (af >= 0) { n = local_addresses(q->manager->rtnl, q->ifindex, af, &addresses); if (n < 0) return n; if (n == 0) { struct local_address buffer[2]; /* If we have no local addresses then use ::1 * and 127.0.0.2 as local ones. */ if (af == AF_INET || af == AF_UNSPEC) buffer[n++] = (struct local_address) { .family = AF_INET, .ifindex = SYNTHESIZE_IFINDEX(q->ifindex), .address.in.s_addr = htobe32(0x7F000002), }; if (af == AF_INET6 || af == AF_UNSPEC) buffer[n++] = (struct local_address) { .family = AF_INET6, .ifindex = SYNTHESIZE_IFINDEX(q->ifindex), .address.in6 = in6addr_loopback, }; return answer_add_addresses_rr(answer, DNS_RESOURCE_KEY_NAME(key), buffer, n); } } return answer_add_addresses_rr(answer, DNS_RESOURCE_KEY_NAME(key), addresses, n); } static int synthesize_system_hostname_ptr(DnsQuery *q, int af, const union in_addr_union *address, DnsAnswer **answer) { _cleanup_free_ struct local_address *addresses = NULL; int n, r; assert(q); assert(address); assert(answer); if (af == AF_INET && address->in.s_addr == htobe32(0x7F000002)) { /* Always map the IPv4 address 127.0.0.2 to the local * hostname, in addition to "localhost": */ r = dns_answer_reserve(answer, 3); if (r < 0) return r; r = answer_add_ptr(answer, "2.0.0.127.in-addr.arpa", q->manager->llmnr_hostname, SYNTHESIZE_IFINDEX(q->ifindex), DNS_ANSWER_AUTHENTICATED); if (r < 0) return r; r = answer_add_ptr(answer, "2.0.0.127.in-addr.arpa", q->manager->mdns_hostname, SYNTHESIZE_IFINDEX(q->ifindex), DNS_ANSWER_AUTHENTICATED); if (r < 0) return r; r = answer_add_ptr(answer, "2.0.0.127.in-addr.arpa", "localhost", SYNTHESIZE_IFINDEX(q->ifindex), DNS_ANSWER_AUTHENTICATED); if (r < 0) return r; return 0; } n = local_addresses(q->manager->rtnl, q->ifindex, af, &addresses); if (n < 0) return n; r = answer_add_addresses_ptr(answer, q->manager->llmnr_hostname, addresses, n, af, address); if (r < 0) return r; return answer_add_addresses_ptr(answer, q->manager->mdns_hostname, addresses, n, af, address); } static int synthesize_gateway_rr(DnsQuery *q, const DnsResourceKey *key, DnsAnswer **answer) { _cleanup_free_ struct local_address *addresses = NULL; int n = 0, af; assert(q); assert(key); assert(answer); af = dns_type_to_af(key->type); if (af >= 0) { n = local_gateways(q->manager->rtnl, q->ifindex, af, &addresses); if (n < 0) return n; } return answer_add_addresses_rr(answer, DNS_RESOURCE_KEY_NAME(key), addresses, n); } static int synthesize_gateway_ptr(DnsQuery *q, int af, const union in_addr_union *address, DnsAnswer **answer) { _cleanup_free_ struct local_address *addresses = NULL; int n; assert(q); assert(address); assert(answer); n = local_gateways(q->manager->rtnl, q->ifindex, af, &addresses); if (n < 0) return n; return answer_add_addresses_ptr(answer, "gateway", addresses, n, af, address); } static int dns_query_synthesize_reply(DnsQuery *q, DnsTransactionState *state) { _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL; DnsResourceKey *key; int r; assert(q); assert(state); /* Tries to synthesize localhost RR replies where appropriate */ if (!IN_SET(*state, DNS_TRANSACTION_RCODE_FAILURE, DNS_TRANSACTION_NO_SERVERS, DNS_TRANSACTION_TIMEOUT, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED)) return 0; DNS_QUESTION_FOREACH(key, q->question_utf8) { union in_addr_union address; const char *name; int af; if (key->class != DNS_CLASS_IN && key->class != DNS_CLASS_ANY) continue; name = DNS_RESOURCE_KEY_NAME(key); if (is_localhost(name)) { r = synthesize_localhost_rr(q, key, &answer); if (r < 0) return log_error_errno(r, "Failed to synthesize localhost RRs: %m"); } else if (manager_is_own_hostname(q->manager, name)) { r = synthesize_system_hostname_rr(q, key, &answer); if (r < 0) return log_error_errno(r, "Failed to synthesize system hostname RRs: %m"); } else if (is_gateway_hostname(name)) { r = synthesize_gateway_rr(q, key, &answer); if (r < 0) return log_error_errno(r, "Failed to synthesize gateway RRs: %m"); } else if ((dns_name_endswith(name, "127.in-addr.arpa") > 0 && dns_name_equal(name, "2.0.0.127.in-addr.arpa") == 0) || dns_name_equal(name, "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa") > 0) { r = synthesize_localhost_ptr(q, key, &answer); if (r < 0) return log_error_errno(r, "Failed to synthesize localhost PTR RRs: %m"); } else if (dns_name_address(name, &af, &address) > 0) { r = synthesize_system_hostname_ptr(q, af, &address, &answer); if (r < 0) return log_error_errno(r, "Failed to synthesize system hostname PTR RR: %m"); r = synthesize_gateway_ptr(q, af, &address, &answer); if (r < 0) return log_error_errno(r, "Failed to synthesize gateway hostname PTR RR: %m"); } } if (!answer) return 0; dns_answer_unref(q->answer); q->answer = answer; answer = NULL; q->answer_rcode = DNS_RCODE_SUCCESS; q->answer_protocol = SYNTHESIZE_PROTOCOL(q->flags); q->answer_family = SYNTHESIZE_FAMILY(q->flags); *state = DNS_TRANSACTION_SUCCESS; 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; 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; dns_query_synthesize_reply(q, &state); 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; } q->answer = dns_answer_unref(q->answer); q->answer_rcode = 0; q->answer_family = AF_UNSPEC; q->answer_protocol = _DNS_PROTOCOL_INVALID; 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) { dns_query_synthesize_reply(q, &state); dns_query_complete(q, state); return; } SET_FOREACH(t, c->transactions, i) { switch (t->state) { case DNS_TRANSACTION_SUCCESS: { /* We found a successfuly reply, merge it into the answer */ r = dns_answer_extend(&q->answer, t->answer); if (r < 0) { dns_query_complete(q, DNS_TRANSACTION_RESOURCES); return; } q->answer_rcode = t->answer_rcode; 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; 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); dns_query_synthesize_reply(q, &state); dns_query_complete(q, state); } 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; 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; /* Turn off searching for the new name */ q->flags |= SD_RESOLVED_NO_SEARCH; 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); }