diff options
Diffstat (limited to 'src/resolve/resolved-dns-query.c')
| -rw-r--r-- | src/resolve/resolved-dns-query.c | 1010 |
1 files changed, 822 insertions, 188 deletions
diff --git a/src/resolve/resolved-dns-query.c b/src/resolve/resolved-dns-query.c index 418d9721ef..53be18efc6 100644 --- a/src/resolve/resolved-dns-query.c +++ b/src/resolve/resolved-dns-query.c @@ -1,5 +1,3 @@ -/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ - /*** This file is part of systemd. @@ -19,41 +17,405 @@ along with systemd; If not, see <http://www.gnu.org/licenses/>. ***/ - +#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 void dns_query_stop(DnsQuery *q) { - DnsTransaction *t; +static int dns_query_candidate_new(DnsQueryCandidate **ret, DnsQuery *q, DnsScope *s) { + DnsQueryCandidate *c; + assert(ret); assert(q); + assert(s); - q->timeout_event_source = sd_event_source_unref(q->timeout_event_source); + 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; - while ((t = set_steal_first(q->transactions))) { - set_remove(t->queries, q); + 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; - dns_query_stop(q); - set_free(q->transactions); + 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); - dns_answer_unref(q->answer); + 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--; @@ -64,17 +426,52 @@ DnsQuery *dns_query_free(DnsQuery *q) { return NULL; } -int dns_query_new(Manager *m, DnsQuery **ret, DnsQuestion *question, int ifindex, uint64_t flags) { +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; - unsigned i; + DnsResourceKey *key; + bool good = false; int r; + char key_str[DNS_RESOURCE_KEY_STRING_MAX]; assert(m); - assert(question); - r = dns_question_is_valid(question); + 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; @@ -83,18 +480,29 @@ int dns_query_new(Manager *m, DnsQuery **ret, DnsQuestion *question, int ifindex if (!q) return -ENOMEM; - q->question = dns_question_ref(question); + 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; - for (i = 0; i < question->n_keys; i++) { - _cleanup_free_ char *p; + /* 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)); - r = dns_resource_key_to_string(question->keys[i], &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) { + r = dns_question_contains(question_utf8, key); if (r < 0) return r; + if (r > 0) + continue; - log_debug("Looking up RR for %s", p); + 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); @@ -108,10 +516,33 @@ int dns_query_new(Manager *m, DnsQuery **ret, DnsQuestion *question, int ifindex 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(!IN_SET(state, DNS_TRANSACTION_NULL, DNS_TRANSACTION_PENDING)); - assert(IN_SET(q->state, DNS_TRANSACTION_NULL, DNS_TRANSACTION_PENDING)); + 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 @@ -134,90 +565,117 @@ static int on_query_timeout(sd_event_source *s, usec_t usec, void *userdata) { return 0; } -static int dns_query_add_transaction(DnsQuery *q, DnsScope *s, DnsResourceKey *key) { - _cleanup_(dns_question_unrefp) DnsQuestion *question = NULL; - DnsTransaction *t; +static int dns_query_add_candidate(DnsQuery *q, DnsScope *s) { + DnsQueryCandidate *c; int r; assert(q); assert(s); - r = set_ensure_allocated(&q->transactions, NULL); + r = dns_query_candidate_new(&c, q, s); if (r < 0) return r; - if (key) { - question = dns_question_new(1); - if (!question) - return -ENOMEM; - - r = dns_question_add(question, key); + /* 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) - return r; - } else - question = dns_question_ref(q->question); + goto fail; + if (r > 0) { + /* OK, we need a search domain now. Let's find one for this scope */ - t = dns_scope_find_transaction(s, question, true); - if (!t) { - r = dns_transaction_new(&t, s, question); - if (r < 0) - return r; + 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 = set_ensure_allocated(&t->queries, NULL); - if (r < 0) - goto gc; - - r = set_put(t->queries, q); + r = dns_query_candidate_setup_transactions(c); if (r < 0) - goto gc; - - r = set_put(q->transactions, t); - if (r < 0) { - set_remove(t->queries, q); - goto gc; - } + goto fail; return 0; -gc: - dns_transaction_gc(t); +fail: + dns_query_candidate_free(c); return r; } -static int dns_query_add_transaction_split(DnsQuery *q, DnsScope *s) { +static int dns_query_synthesize_reply(DnsQuery *q, DnsTransactionState *state) { + _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL; int r; assert(q); - assert(s); + 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 (s->protocol == DNS_PROTOCOL_MDNS) { - r = dns_query_add_transaction(q, s, NULL); - if (r < 0) - return r; - } else { - unsigned i; + r = dns_synthesize_answer( + q->manager, + q->question_utf8, + q->ifindex, + &answer); - /* On DNS and LLMNR we can only send a single - * question per datagram, hence issue multiple - * transactions. */ + if (r <= 0) + return r; - for (i = 0; i < q->question->n_keys; i++) { - r = dns_query_add_transaction(q, s, q->question->keys[i]); - if (r < 0) - return r; - } - } + dns_query_reset_answer(q); - return 0; + 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; - DnsTransaction *t; - const char *name; - Iterator i; + DnsQueryCandidate *c; int r; assert(q); @@ -225,13 +683,21 @@ int dns_query_go(DnsQuery *q) { if (q->state != DNS_TRANSACTION_NULL) return 0; - assert(q->question); - assert(q->question->n_keys > 0); - - name = DNS_RESOURCE_KEY_NAME(q->question->keys[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) @@ -253,15 +719,28 @@ int dns_query_go(DnsQuery *q) { } } - if (found == DNS_SCOPE_NO) - return -ESRCH; + if (found == DNS_SCOPE_NO) { + DnsTransactionState state = DNS_TRANSACTION_NO_SERVERS; + + r = dns_query_synthesize_reply(q, &state); + if (r < 0) + return r; - r = dns_query_add_transaction_split(q, first); + 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) @@ -270,16 +749,12 @@ int dns_query_go(DnsQuery *q) { if (match != found) continue; - r = dns_query_add_transaction_split(q, s); + r = dns_query_add_candidate(q, s); if (r < 0) goto fail; } - q->answer = dns_answer_unref(q->answer); - q->answer_ifindex = 0; - q->answer_rcode = 0; - q->answer_family = AF_UNSPEC; - q->answer_protocol = _DNS_PROTOCOL_INVALID; + dns_query_reset_answer(q); r = sd_event_add_time( q->manager->event, @@ -290,17 +765,18 @@ int dns_query_go(DnsQuery *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 that are not started yet */ - SET_FOREACH(t, q->transactions, i) { - if (t->state != DNS_TRANSACTION_NULL) - continue; - - r = dns_transaction_go(t); - if (r < 0) + /* 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--; @@ -313,149 +789,268 @@ fail: return r; } -void dns_query_ready(DnsQuery *q) { - DnsTransaction *t; +static void dns_query_accept(DnsQuery *q, DnsQueryCandidate *c) { DnsTransactionState state = DNS_TRANSACTION_NO_SERVERS; - _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL; - int rcode = 0; - DnsScope *scope = NULL; - bool pending = false; + 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); - assert(IN_SET(q->state, DNS_TRANSACTION_NULL, DNS_TRANSACTION_PENDING)); - /* 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 (!c) { + r = dns_query_synthesize_reply(q, &state); + if (r < 0) + goto fail; - if (q->block_ready > 0) + dns_query_complete(q, state); return; + } - SET_FOREACH(t, q->transactions, i) { - - /* If we found a successful answer, ignore all answers from other scopes */ - if (state == DNS_TRANSACTION_SUCCESS && t->scope != scope) - continue; - - /* One of the transactions is still going on, let's maybe wait for it */ - if (IN_SET(t->state, DNS_TRANSACTION_PENDING, DNS_TRANSACTION_NULL)) { - pending = true; - continue; - } + 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; + } - /* One of the transactions is successful, let's use - * it, and copy its data out */ - if (t->state == DNS_TRANSACTION_SUCCESS) { - DnsAnswer *a; + SET_FOREACH(t, c->transactions, i) { - if (t->received) { - rcode = DNS_PACKET_RCODE(t->received); - a = t->received->answer; - } else { - rcode = t->cached_rcode; - a = t->cached; - } + switch (t->state) { - if (state == DNS_TRANSACTION_SUCCESS) { - DnsAnswer *merged; + 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; - merged = dns_answer_merge(answer, a); - if (!merged) { - dns_query_complete(q, DNS_TRANSACTION_RESOURCES); - return; - } + q->answer_rcode = t->answer_rcode; + q->answer_errno = 0; - dns_answer_unref(answer); - answer = merged; + if (t->answer_authenticated) { + has_authenticated = true; + dnssec_result_authenticated = t->answer_dnssec_result; } else { - dns_answer_unref(answer); - answer = dns_answer_ref(a); + has_non_authenticated = true; + dnssec_result_non_authenticated = t->answer_dnssec_result; } - scope = t->scope; state = DNS_TRANSACTION_SUCCESS; - continue; + break; } - /* One of the transactions has failed, let's see - * whether we find anything better, but if not, return - * its response data */ - if (state != DNS_TRANSACTION_SUCCESS && t->state == DNS_TRANSACTION_FAILURE) { - DnsAnswer *a; + case DNS_TRANSACTION_NULL: + case DNS_TRANSACTION_PENDING: + case DNS_TRANSACTION_VALIDATING: + case DNS_TRANSACTION_ABORTED: + /* Ignore transactions that didn't complete */ + continue; - if (t->received) { - rcode = DNS_PACKET_RCODE(t->received); - a = t->received->answer; - } else { - rcode = t->cached_rcode; - a = t->cached; - } + default: + /* Any kind of failure? Store the data away, + * if there's nothing stored yet. */ - dns_answer_unref(answer); - answer = dns_answer_ref(a); + if (state == DNS_TRANSACTION_SUCCESS) + continue; - scope = t->scope; - state = DNS_TRANSACTION_FAILURE; - 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; - if (state == DNS_TRANSACTION_NO_SERVERS && t->state != DNS_TRANSACTION_NO_SERVERS) state = t->state; + break; + } } - if (pending) { + 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)); - /* If so far we weren't successful, and there's - * something still pending, then wait for it */ - if (state != DNS_TRANSACTION_SUCCESS) + /* 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; - /* If we already were successful, then only wait for - * other transactions on the same scope to finish. */ - SET_FOREACH(t, q->transactions, i) { - if (t->scope == scope && IN_SET(t->state, DNS_TRANSACTION_PENDING, DNS_TRANSACTION_NULL)) - 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 (IN_SET(state, DNS_TRANSACTION_SUCCESS, DNS_TRANSACTION_FAILURE)) { - q->answer = dns_answer_ref(answer); - q->answer_rcode = rcode; - q->answer_ifindex = (scope && scope->link) ? scope->link->ifindex : 0; - q->answer_protocol = scope ? scope->protocol : _DNS_PROTOCOL_INVALID; - q->answer_family = scope ? scope->family : AF_UNSPEC; - } + if (pending) + return; - dns_query_complete(q, state); + dns_query_accept(q, bad); } -int dns_query_cname_redirect(DnsQuery *q, const char *name) { - _cleanup_(dns_question_unrefp) DnsQuestion *nq = NULL; - int r; +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, name, &nq); + 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)); - dns_question_unref(q->question); - q->question = nq; - nq = NULL; + 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)); + } - q->n_cname_redirects++; + 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); - dns_query_stop(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; @@ -485,3 +1080,42 @@ int dns_query_bus_track(DnsQuery *q, sd_bus_message *m) { 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); +} |