| /* SPDX-License-Identifier: LGPL-2.1-or-later */ |
| |
| #include "alloc-util.h" |
| #include "dns-domain.h" |
| #include "dns-type.h" |
| #include "event-util.h" |
| #include "glyph-util.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" |
| |
| #define QUERIES_MAX 2048 |
| #define AUXILIARY_QUERIES_MAX 64 |
| #define CNAME_REDIRECTS_MAX 16 |
| |
| assert_cc(AUXILIARY_QUERIES_MAX < UINT8_MAX); |
| assert_cc(CNAME_REDIRECTS_MAX < UINT8_MAX); |
| |
| static int dns_query_candidate_new(DnsQueryCandidate **ret, DnsQuery *q, DnsScope *s) { |
| DnsQueryCandidate *c; |
| |
| assert(ret); |
| assert(q); |
| assert(s); |
| |
| c = new(DnsQueryCandidate, 1); |
| if (!c) |
| return -ENOMEM; |
| |
| *c = (DnsQueryCandidate) { |
| .n_ref = 1, |
| .query = q, |
| .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); |
| |
| /* Detach all the DnsTransactions attached to this query */ |
| |
| 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); |
| } |
| } |
| |
| static DnsQueryCandidate* dns_query_candidate_unlink(DnsQueryCandidate *c) { |
| assert(c); |
| |
| /* Detach this DnsQueryCandidate from the Query and Scope objects */ |
| |
| if (c->query) { |
| LIST_REMOVE(candidates_by_query, c->query->candidates, c); |
| c->query = NULL; |
| } |
| |
| if (c->scope) { |
| LIST_REMOVE(candidates_by_scope, c->scope->query_candidates, c); |
| c->scope = NULL; |
| } |
| |
| return c; |
| } |
| |
| static DnsQueryCandidate* dns_query_candidate_free(DnsQueryCandidate *c) { |
| if (!c) |
| return NULL; |
| |
| dns_query_candidate_stop(c); |
| dns_query_candidate_unlink(c); |
| |
| set_free(c->transactions); |
| dns_search_domain_unref(c->search_domain); |
| |
| return mfree(c); |
| } |
| |
| DEFINE_PUBLIC_TRIVIAL_REF_UNREF_FUNC(DnsQueryCandidate, dns_query_candidate, dns_query_candidate_free); |
| |
| static int dns_query_candidate_next_search_domain(DnsQueryCandidate *c) { |
| DnsSearchDomain *next; |
| |
| 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, |
| DnsPacket *bypass) { |
| |
| _cleanup_(dns_transaction_gcp) DnsTransaction *t = NULL; |
| int r; |
| |
| assert(c); |
| assert(c->query); /* We shan't add transactions to a candidate that has been detached already */ |
| |
| if (key) { |
| /* Regular lookup with a resource key */ |
| assert(!bypass); |
| |
| t = dns_scope_find_transaction(c->scope, key, c->query->flags); |
| if (!t) { |
| r = dns_transaction_new(&t, c->scope, key, NULL, c->query->flags); |
| if (r < 0) |
| return r; |
| } else if (set_contains(c->transactions, t)) |
| return 0; |
| } else { |
| /* "Bypass" lookup with a query packet */ |
| assert(bypass); |
| |
| r = dns_transaction_new(&t, c->scope, NULL, bypass, c->query->flags); |
| if (r < 0) |
| return r; |
| } |
| |
| r = set_ensure_allocated(&t->notify_query_candidates_done, NULL); |
| if (r < 0) |
| return r; |
| |
| r = set_ensure_put(&t->notify_query_candidates, NULL, c); |
| if (r < 0) |
| return r; |
| |
| r = set_ensure_put(&c->transactions, NULL, t); |
| if (r < 0) { |
| (void) set_remove(t->notify_query_candidates, c); |
| return r; |
| } |
| |
| TAKE_PTR(t); |
| return 1; |
| } |
| |
| static int dns_query_candidate_go(DnsQueryCandidate *c) { |
| _unused_ _cleanup_(dns_query_candidate_unrefp) DnsQueryCandidate *keep_c = NULL; |
| DnsTransaction *t; |
| int r; |
| unsigned n = 0; |
| |
| assert(c); |
| |
| /* Let's keep a reference to the query while we're operating */ |
| keep_c = dns_query_candidate_ref(c); |
| |
| /* Start the transactions that are not started yet */ |
| SET_FOREACH(t, c->transactions) { |
| 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; |
| |
| assert(c); |
| |
| if (c->error_code != 0) |
| return DNS_TRANSACTION_ERRNO; |
| |
| SET_FOREACH(t, c->transactions) |
| |
| 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); |
| assert(c->query); /* We shan't add transactions to a candidate that has been detached already */ |
| |
| dns_query_candidate_stop(c); |
| |
| if (c->query->question_bypass) { |
| /* If this is a bypass query, then pass the original query packet along to the transaction */ |
| |
| assert(dns_question_size(c->query->question_bypass->question) == 1); |
| |
| if (!dns_scope_good_key(c->scope, dns_question_first_key(c->query->question_bypass->question))) |
| return 0; |
| |
| r = dns_query_candidate_add_transaction(c, NULL, c->query->question_bypass); |
| if (r < 0) |
| goto fail; |
| |
| return 1; |
| } |
| |
| 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 (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, NULL); |
| 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); |
| |
| if (!c->query) /* This candidate has been abandoned, do nothing. */ |
| return; |
| |
| 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: |
| c->error_code = log_warning_errno(r, "Failed to follow search domains: %m"); |
| dns_query_ready(c->query); |
| } |
| |
| static void dns_query_stop(DnsQuery *q) { |
| assert(q); |
| |
| event_source_disable(q->timeout_event_source); |
| |
| LIST_FOREACH(candidates_by_query, c, q->candidates) |
| dns_query_candidate_stop(c); |
| } |
| |
| static void dns_query_unlink_candidates(DnsQuery *q) { |
| assert(q); |
| |
| while (q->candidates) |
| /* Here we drop *our* references to each of the candidates. If we had the only reference, the |
| * DnsQueryCandidate object will be freed. */ |
| dns_query_candidate_unref(dns_query_candidate_unlink(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_query_flags = 0; |
| q->answer_protocol = _DNS_PROTOCOL_INVALID; |
| q->answer_family = AF_UNSPEC; |
| q->answer_search_domain = dns_search_domain_unref(q->answer_search_domain); |
| q->answer_full_packet = dns_packet_unref(q->answer_full_packet); |
| } |
| |
| DnsQuery *dns_query_free(DnsQuery *q) { |
| if (!q) |
| return NULL; |
| |
| q->timeout_event_source = sd_event_source_disable_unref(q->timeout_event_source); |
| |
| 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_unlink_candidates(q); |
| |
| dns_question_unref(q->question_idna); |
| dns_question_unref(q->question_utf8); |
| dns_packet_unref(q->question_bypass); |
| dns_question_unref(q->collected_questions); |
| |
| dns_query_reset_answer(q); |
| |
| sd_bus_message_unref(q->bus_request); |
| sd_bus_track_unref(q->bus_track); |
| |
| if (q->varlink_request) { |
| varlink_set_userdata(q->varlink_request, NULL); |
| varlink_unref(q->varlink_request); |
| } |
| |
| if (q->request_packet) |
| hashmap_remove_value(q->stub_listener_extra ? |
| q->stub_listener_extra->queries_by_packet : |
| q->manager->stub_queries_by_packet, |
| q->request_packet, |
| q); |
| |
| dns_packet_unref(q->request_packet); |
| dns_answer_unref(q->reply_answer); |
| dns_answer_unref(q->reply_authoritative); |
| dns_answer_unref(q->reply_additional); |
| |
| if (q->request_stream) { |
| /* Detach the stream from our query, in case something else keeps a reference to it. */ |
| (void) set_remove(q->request_stream->queries, q); |
| q->request_stream = dns_stream_unref(q->request_stream); |
| } |
| |
| free(q->request_address_string); |
| |
| if (q->manager) { |
| LIST_REMOVE(queries, q->manager->dns_queries, q); |
| q->manager->n_dns_queries--; |
| } |
| |
| return mfree(q); |
| } |
| |
| int dns_query_new( |
| Manager *m, |
| DnsQuery **ret, |
| DnsQuestion *question_utf8, |
| DnsQuestion *question_idna, |
| DnsPacket *question_bypass, |
| int ifindex, |
| uint64_t flags) { |
| |
| _cleanup_(dns_query_freep) DnsQuery *q = NULL; |
| char key_str[DNS_RESOURCE_KEY_STRING_MAX]; |
| DnsResourceKey *key; |
| int r; |
| |
| assert(m); |
| |
| if (question_bypass) { |
| /* It's either a "bypass" query, or a regular one, but can't be both. */ |
| if (question_utf8 || question_idna) |
| return -EINVAL; |
| |
| } else { |
| bool good = false; |
| |
| /* This (primarily) checks two things: |
| * |
| * 1. That the question is not empty |
| * 2. That all RR keys in the question objects are for the same domain |
| * |
| * Or in other words, a single DnsQuery object may be used to look up A+AAAA combination for |
| * the same domain name, or SRV+TXT (for DNS-SD services), but not for unrelated lookups. */ |
| |
| 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 = new(DnsQuery, 1); |
| if (!q) |
| return -ENOMEM; |
| |
| *q = (DnsQuery) { |
| .question_utf8 = dns_question_ref(question_utf8), |
| .question_idna = dns_question_ref(question_idna), |
| .question_bypass = dns_packet_ref(question_bypass), |
| .ifindex = ifindex, |
| .flags = flags, |
| .answer_dnssec_result = _DNSSEC_RESULT_INVALID, |
| .answer_protocol = _DNS_PROTOCOL_INVALID, |
| .answer_family = AF_UNSPEC, |
| }; |
| |
| if (question_bypass) { |
| DNS_QUESTION_FOREACH(key, question_bypass->question) |
| log_debug("Looking up bypass packet for %s.", |
| dns_resource_key_to_string(key, key_str, sizeof key_str)); |
| } else { |
| /* 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_key(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; |
| |
| TAKE_PTR(q); |
| 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; |
| } |
| |
| 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; |
| |
| (void) manager_monitor_send(q->manager, q->state, q->answer_rcode, q->answer_errno, q->question_idna, q->question_utf8, q->collected_questions, q->answer); |
| |
| 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 = ASSERT_PTR(userdata); |
| |
| assert(s); |
| |
| dns_query_complete(q, DNS_TRANSACTION_TIMEOUT); |
| return 0; |
| } |
| |
| static int dns_query_add_candidate(DnsQuery *q, DnsScope *s) { |
| _cleanup_(dns_query_candidate_unrefp) DnsQueryCandidate *c = NULL; |
| 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 (!FLAGS_SET(q->flags, SD_RESOLVED_NO_SEARCH) && |
| dns_scope_name_wants_search_domain(s, dns_question_first_name(q->question_idna))) { |
| /* OK, we want a search domain now. Let's find one for this scope */ |
| |
| r = dns_query_candidate_next_search_domain(c); |
| if (r < 0) |
| return r; |
| } |
| |
| r = dns_query_candidate_setup_transactions(c); |
| if (r < 0) |
| return r; |
| |
| TAKE_PTR(c); |
| return 0; |
| } |
| |
| 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; |
| |
| if (FLAGS_SET(q->flags, SD_RESOLVED_NO_SYNTHESIZE)) |
| return 0; |
| |
| r = dns_synthesize_answer( |
| q->manager, |
| q->question_bypass ? q->question_bypass->question : q->question_utf8, |
| q->ifindex, |
| &answer); |
| if (r == -ENXIO) { |
| /* If we get ENXIO this tells us to generate NXDOMAIN unconditionally. */ |
| |
| dns_query_reset_answer(q); |
| q->answer_rcode = DNS_RCODE_NXDOMAIN; |
| q->answer_protocol = dns_synthesize_protocol(q->flags); |
| q->answer_family = dns_synthesize_family(q->flags); |
| q->answer_query_flags = SD_RESOLVED_AUTHENTICATED|SD_RESOLVED_CONFIDENTIAL|SD_RESOLVED_SYNTHETIC; |
| *state = DNS_TRANSACTION_RCODE_FAILURE; |
| |
| return 0; |
| } |
| if (r <= 0) |
| return r; |
| |
| dns_query_reset_answer(q); |
| |
| q->answer = TAKE_PTR(answer); |
| q->answer_rcode = DNS_RCODE_SUCCESS; |
| q->answer_protocol = dns_synthesize_protocol(q->flags); |
| q->answer_family = dns_synthesize_family(q->flags); |
| q->answer_query_flags = SD_RESOLVED_AUTHENTICATED|SD_RESOLVED_CONFIDENTIAL|SD_RESOLVED_SYNTHETIC; |
| |
| *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. */ |
| |
| if (FLAGS_SET(q->flags, SD_RESOLVED_NO_SYNTHESIZE)) |
| return 0; |
| |
| r = manager_etc_hosts_lookup( |
| q->manager, |
| q->question_bypass ? q->question_bypass->question : q->question_utf8, |
| &answer); |
| if (r <= 0) |
| return r; |
| |
| dns_query_reset_answer(q); |
| |
| q->answer = TAKE_PTR(answer); |
| q->answer_rcode = DNS_RCODE_SUCCESS; |
| q->answer_protocol = dns_synthesize_protocol(q->flags); |
| q->answer_family = dns_synthesize_family(q->flags); |
| q->answer_query_flags = SD_RESOLVED_AUTHENTICATED|SD_RESOLVED_CONFIDENTIAL|SD_RESOLVED_SYNTHETIC; |
| |
| return 1; |
| } |
| |
| int dns_query_go(DnsQuery *q) { |
| DnsScopeMatch found = DNS_SCOPE_NO; |
| DnsScope *first = NULL; |
| 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; |
| |
| match = dns_scope_good_domain(s, q); |
| assert(match >= 0); |
| if (match > found) { /* Does this match better? If so, remember how well it matched, and the first one |
| * that matches this well */ |
| found = match; |
| 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; |
| |
| match = dns_scope_good_domain(s, q); |
| assert(match >= 0); |
| if (match < found) |
| continue; |
| |
| r = dns_query_add_candidate(q, s); |
| if (r < 0) |
| goto fail; |
| } |
| |
| dns_query_reset_answer(q); |
| |
| r = event_reset_time_relative( |
| q->manager->event, |
| &q->timeout_event_source, |
| CLOCK_BOOTTIME, |
| SD_RESOLVED_QUERY_TIMEOUT_USEC, |
| 0, on_query_timeout, q, |
| 0, "query-timeout", true); |
| if (r < 0) |
| goto fail; |
| |
| 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, has_confidential = false, has_non_confidential = false; |
| DnssecResult dnssec_result_authenticated = _DNSSEC_RESULT_INVALID, dnssec_result_non_authenticated = _DNSSEC_RESULT_INVALID; |
| DnsTransaction *t; |
| 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_query_flags = 0; |
| q->answer_errno = c->error_code; |
| q->answer_full_packet = dns_packet_unref(q->answer_full_packet); |
| } |
| |
| SET_FOREACH(t, c->transactions) { |
| |
| switch (t->state) { |
| |
| case DNS_TRANSACTION_SUCCESS: { |
| /* We found a successful reply, merge it into the answer */ |
| |
| if (state == DNS_TRANSACTION_SUCCESS) { |
| r = dns_answer_extend(&q->answer, t->answer); |
| if (r < 0) |
| goto fail; |
| |
| q->answer_query_flags |= dns_transaction_source_to_query_flags(t->answer_source); |
| } else { |
| /* Override non-successful previous answers */ |
| DNS_ANSWER_REPLACE(q->answer, dns_answer_ref(t->answer)); |
| q->answer_query_flags = dns_transaction_source_to_query_flags(t->answer_source); |
| } |
| |
| q->answer_rcode = t->answer_rcode; |
| q->answer_errno = 0; |
| |
| DNS_PACKET_REPLACE(q->answer_full_packet, dns_packet_ref(t->received)); |
| |
| if (FLAGS_SET(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED)) { |
| has_authenticated = true; |
| dnssec_result_authenticated = t->answer_dnssec_result; |
| } else { |
| has_non_authenticated = true; |
| dnssec_result_non_authenticated = t->answer_dnssec_result; |
| } |
| |
| if (FLAGS_SET(t->answer_query_flags, SD_RESOLVED_CONFIDENTIAL)) |
| has_confidential = true; |
| else |
| has_non_confidential = true; |
| |
| 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; |
| |
| /* If there's already an authenticated negative reply stored, then prefer that over any unauthenticated one */ |
| if (FLAGS_SET(q->answer_query_flags, SD_RESOLVED_AUTHENTICATED) && |
| !FLAGS_SET(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED)) |
| continue; |
| |
| DNS_ANSWER_REPLACE(q->answer, dns_answer_ref(t->answer)); |
| q->answer_rcode = t->answer_rcode; |
| q->answer_dnssec_result = t->answer_dnssec_result; |
| q->answer_query_flags = t->answer_query_flags | dns_transaction_source_to_query_flags(t->answer_source); |
| q->answer_errno = t->answer_errno; |
| DNS_PACKET_REPLACE(q->answer_full_packet, dns_packet_ref(t->received)); |
| |
| state = t->state; |
| break; |
| } |
| } |
| |
| if (state == DNS_TRANSACTION_SUCCESS) { |
| SET_FLAG(q->answer_query_flags, SD_RESOLVED_AUTHENTICATED, has_authenticated && !has_non_authenticated); |
| SET_FLAG(q->answer_query_flags, SD_RESOLVED_CONFIDENTIAL, has_confidential && !has_non_confidential); |
| q->answer_dnssec_result = FLAGS_SET(q->answer_query_flags, SD_RESOLVED_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; |
| 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_collect_question(DnsQuery *q, DnsQuestion *question) { |
| _cleanup_(dns_question_unrefp) DnsQuestion *merged = NULL; |
| int r; |
| |
| assert(q); |
| |
| if (dns_question_size(question) == 0) |
| return 0; |
| |
| /* When redirecting, save the first element in the chain, for informational purposes when monitoring */ |
| r = dns_question_merge(q->collected_questions, question, &merged); |
| if (r < 0) |
| return r; |
| |
| dns_question_unref(q->collected_questions); |
| q->collected_questions = TAKE_PTR(merged); |
| |
| return 0; |
| } |
| |
| 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); |
| |
| if (q->n_cname_redirects >= CNAME_REDIRECTS_MAX) |
| return -ELOOP; |
| q->n_cname_redirects++; |
| |
| r = dns_question_cname_redirect(q->question_idna, cname, &nq_idna); |
| if (r < 0) |
| return r; |
| if (r > 0) |
| log_debug("Following CNAME/DNAME %s %s %s.", |
| dns_question_first_name(q->question_idna), |
| special_glyph(SPECIAL_GLYPH_ARROW_RIGHT), |
| dns_question_first_name(nq_idna)); |
| |
| k = dns_question_is_equal(q->question_idna, q->question_utf8); |
| if (k < 0) |
| return k; |
| 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; |
| if (k > 0) |
| log_debug("Following UTF8 CNAME/DNAME %s %s %s.", |
| dns_question_first_name(q->question_utf8), |
| special_glyph(SPECIAL_GLYPH_ARROW_RIGHT), |
| 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; |
| |
| r = dns_query_collect_question(q, q->question_idna); |
| if (r < 0) |
| return r; |
| r = dns_query_collect_question(q, q->question_utf8); |
| if (r < 0) |
| return r; |
| |
| /* Install the redirected question */ |
| dns_question_unref(q->question_idna); |
| q->question_idna = TAKE_PTR(nq_idna); |
| |
| dns_question_unref(q->question_utf8); |
| q->question_utf8 = TAKE_PTR(nq_utf8); |
| |
| dns_query_unlink_candidates(q); |
| |
| /* Note that we do *not* reset the answer here, because the answer we previously got might already |
| * include everything we need, let's check that first */ |
| |
| q->state = DNS_TRANSACTION_NULL; |
| |
| return 0; |
| } |
| |
| int dns_query_process_cname_one(DnsQuery *q) { |
| _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *cname = NULL; |
| DnsQuestion *question; |
| DnsResourceRecord *rr; |
| bool full_match = true; |
| DnsResourceKey *k; |
| int r; |
| |
| assert(q); |
| |
| /* Processes a CNAME redirect if there's one. Returns one of three values: |
| * |
| * CNAME_QUERY_MATCH → direct RR match, caller should just use the RRs in this answer (and not |
| * bother with any CNAME/DNAME stuff) |
| * |
| * CNAME_QUERY_NOMATCH → no match at all, neither direct nor CNAME/DNAME, caller might decide to |
| * restart query or take things as NODATA reply. |
| * |
| * CNAME_QUERY_CNAME → no direct RR match, but a CNAME/DNAME match that we now followed for one step. |
| * |
| * The function might also return a failure, in particular -ELOOP if we encountered too many |
| * CNAMEs/DNAMEs in a chain or if following CNAMEs/DNAMEs was turned off. |
| * |
| * Note that this function doesn't actually restart the query. The caller can decide to do that in |
| * case of CNAME_QUERY_CNAME, though. */ |
| |
| 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); |
| |
| /* Small reminder: our question will consist of one or more RR keys that match in name, but not in |
| * record type. Specifically, when we do an address lookup the question will typically consist of one |
| * A and one AAAA key lookup for the same domain name. When we get a response from a server we need |
| * to check if the answer answers all our questions to use it. Note that a response of CNAME/DNAME |
| * can answer both an A and the AAAA question for us, but an A/AAAA response only the relevant |
| * type. |
| * |
| * Hence we first check of the answers we collected are sufficient to answer all our questions |
| * directly. If one question wasn't answered we go on, waiting for more replies. However, if there's |
| * a CNAME/DNAME response we use it, and redirect to it, regardless if it was a response to the A or |
| * the AAAA query. */ |
| |
| DNS_QUESTION_FOREACH(k, question) { |
| bool match = false; |
| |
| DNS_ANSWER_FOREACH(rr, q->answer) { |
| r = dns_resource_key_match_rr(k, rr, DNS_SEARCH_DOMAIN_NAME(q->answer_search_domain)); |
| if (r < 0) |
| return r; |
| if (r > 0) { |
| match = true; /* Yay, we found an RR that matches the key we are looking for */ |
| break; |
| } |
| } |
| |
| if (!match) { |
| /* Hmm. :-( there's no response for this key. This doesn't match. */ |
| full_match = false; |
| break; |
| } |
| } |
| |
| if (full_match) |
| return DNS_QUERY_MATCH; /* The answer can answer our question in full, no need to follow CNAMEs/DNAMEs */ |
| |
| /* Let's see if there is a CNAME/DNAME to match. This case is simpler: we accept the CNAME/DNAME that |
| * matches any of our questions. */ |
| DNS_ANSWER_FOREACH(rr, q->answer) { |
| 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/DNAME to follow */ |
| |
| if (q->flags & SD_RESOLVED_NO_CNAME) |
| return -ELOOP; |
| |
| if (!FLAGS_SET(q->answer_query_flags, SD_RESOLVED_AUTHENTICATED)) |
| q->previous_redirect_unauthenticated = true; |
| if (!FLAGS_SET(q->answer_query_flags, SD_RESOLVED_CONFIDENTIAL)) |
| q->previous_redirect_non_confidential = true; |
| if (!FLAGS_SET(q->answer_query_flags, SD_RESOLVED_SYNTHETIC)) |
| q->previous_redirect_non_synthetic = true; |
| |
| /* OK, let's actually follow the CNAME */ |
| r = dns_query_cname_redirect(q, cname); |
| if (r < 0) |
| return r; |
| |
| return DNS_QUERY_CNAME; /* Tell caller that we did a single CNAME/DNAME redirection step */ |
| } |
| |
| int dns_query_process_cname_many(DnsQuery *q) { |
| int r; |
| |
| assert(q); |
| |
| /* Follows CNAMEs through the current packet: as long as the current packet can fulfill our |
| * redirected CNAME queries we keep going, and restart the query once the current packet isn't good |
| * enough anymore. It's a wrapper around dns_query_process_cname_one() and returns the same values, |
| * but with extended semantics. Specifically: |
| * |
| * DNS_QUERY_MATCH → as above |
| * |
| * DNS_QUERY_CNAME → we ran into a CNAME/DNAME redirect that we could not answer from the current |
| * message, and thus restarted the query to resolve it. |
| * |
| * DNS_QUERY_NOMATCH → we reached the end of CNAME/DNAME chain, and there are no direct matches nor a |
| * CNAME/DNAME match. i.e. this is a NODATA case. |
| * |
| * Note that this function will restart the query for the caller if needed, and that's the case |
| * DNS_QUERY_CNAME is returned. |
| */ |
| |
| r = dns_query_process_cname_one(q); |
| if (r != DNS_QUERY_CNAME) |
| return r; /* The first redirect is special: if it doesn't answer the question that's no |
| * reason to restart the query, we just accept this as a NODATA answer. */ |
| |
| for (;;) { |
| r = dns_query_process_cname_one(q); |
| if (r < 0 || r == DNS_QUERY_MATCH) |
| return r; |
| if (r == DNS_QUERY_NOMATCH) { |
| /* OK, so we followed one or more CNAME/DNAME RR but the existing packet can't answer |
| * this. Let's restart the query hence, with the new question. Why the different |
| * handling than the first chain element? Because if the server answers a direct |
| * question with an empty answer then this is a NODATA response. But if it responds |
| * with a CNAME chain that ultimately is incomplete (i.e. a non-empty but truncated |
| * CNAME chain) then we better follow up ourselves and ask for the rest of the |
| * chain. This is particular relevant since our cache will store CNAME/DNAME |
| * redirects that we learnt about for lookups of certain DNS types, but later on we |
| * can reuse this data even for other DNS types, but in that case need to follow up |
| * with the final lookup of the chain ourselves with the RR type we ourselves are |
| * interested in. */ |
| r = dns_query_go(q); |
| if (r < 0) |
| return r; |
| |
| return DNS_QUERY_CNAME; |
| } |
| |
| /* So we found a CNAME that the existing packet already answers, again via a CNAME, let's |
| * continue going then. */ |
| assert(r == DNS_QUERY_CNAME); |
| } |
| } |
| |
| DnsQuestion* dns_query_question_for_protocol(DnsQuery *q, DnsProtocol protocol) { |
| assert(q); |
| |
| if (q->question_bypass) |
| return q->question_bypass->question; |
| |
| 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->question_bypass) |
| return dns_question_first_name(q->question_bypass->question); |
| |
| 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); |
| } |
| |
| bool dns_query_fully_authenticated(DnsQuery *q) { |
| assert(q); |
| |
| return FLAGS_SET(q->answer_query_flags, SD_RESOLVED_AUTHENTICATED) && !q->previous_redirect_unauthenticated; |
| } |
| |
| bool dns_query_fully_confidential(DnsQuery *q) { |
| assert(q); |
| |
| return FLAGS_SET(q->answer_query_flags, SD_RESOLVED_CONFIDENTIAL) && !q->previous_redirect_non_confidential; |
| } |
| |
| bool dns_query_fully_authoritative(DnsQuery *q) { |
| assert(q); |
| |
| /* We are authoritative for everything synthetic (except if a previous CNAME/DNAME) wasn't |
| * synthetic. (Note: SD_RESOLVED_SYNTHETIC is reset on each CNAME/DNAME, hence the explicit check for |
| * previous synthetic DNAME/CNAME redirections.) */ |
| if ((q->answer_query_flags & SD_RESOLVED_SYNTHETIC) && !q->previous_redirect_non_synthetic) |
| return true; |
| |
| /* We are also authoritative for everything coming only from the trust anchor and the local |
| * zones. (Note: the SD_RESOLVED_FROM_xyz flags we merge on each redirect, hence no need to |
| * explicitly check previous redirects here.) */ |
| return (q->answer_query_flags & SD_RESOLVED_FROM_MASK & ~(SD_RESOLVED_FROM_TRUST_ANCHOR | SD_RESOLVED_FROM_ZONE)) == 0; |
| } |
