X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=src%2Fresolve%2Fresolved-dns-query.c;h=22770023047fdd3cd18b84cd42c9bccb2b15459f;hp=5bd59202544920c619c813e739df54a1db632e79;hb=e4501ed4e66e31f5bc6e40046ac8f27ce6e13a5c;hpb=ad867662936a4c7ab2c7116d804c272338801231 diff --git a/src/resolve/resolved-dns-query.c b/src/resolve/resolved-dns-query.c index 5bd592025..227700230 100644 --- a/src/resolve/resolved-dns-query.c +++ b/src/resolve/resolved-dns-query.c @@ -19,32 +19,60 @@ along with systemd; If not, see . ***/ +#include "af-list.h" + #include "resolved-dns-query.h" #include "resolved-dns-domain.h" -#define TRANSACTION_TIMEOUT_USEC (5 * USEC_PER_SEC) +/* After how much time to repeat classic DNS requests */ +#define DNS_TRANSACTION_TIMEOUT_USEC (5 * USEC_PER_SEC) + +/* After how much time to repeat LLMNR requests, see RFC 4795 Section 7 */ +#define LLMNR_TRANSACTION_TIMEOUT_USEC (1 * USEC_PER_SEC) + +/* How long to wait for the query in total */ #define QUERY_TIMEOUT_USEC (30 * USEC_PER_SEC) -#define ATTEMPTS_MAX 8 + +/* Maximum attempts to send DNS requests, across all DNS servers */ +#define DNS_TRANSACTION_ATTEMPTS_MAX 8 + +/* Maximum attempts to send LLMNR requests, see RFC 4795 Section 2.7 */ +#define LLMNR_TRANSACTION_ATTEMPTS_MAX 3 + +#define CNAME_MAX 8 +#define QUERIES_MAX 2048 + +#define TRANSACTION_TIMEOUT_USEC(p) ((t)->scope->protocol == DNS_PROTOCOL_LLMNR ? LLMNR_TRANSACTION_TIMEOUT_USEC : DNS_TRANSACTION_TIMEOUT_USEC) +#define TRANSACTION_ATTEMPTS_MAX(p) ((t)->scope->protocol == DNS_PROTOCOL_LLMNR ? LLMNR_TRANSACTION_ATTEMPTS_MAX : DNS_TRANSACTION_ATTEMPTS_MAX) + +static int dns_query_transaction_go(DnsQueryTransaction *t); DnsQueryTransaction* dns_query_transaction_free(DnsQueryTransaction *t) { + DnsQuery *q; + if (!t) return NULL; sd_event_source_unref(t->timeout_event_source); + dns_question_unref(t->question); dns_packet_unref(t->sent); dns_packet_unref(t->received); + dns_answer_unref(t->cached); + + dns_stream_free(t->stream); - sd_event_source_unref(t->tcp_event_source); - safe_close(t->tcp_fd); + if (t->scope) { + LIST_REMOVE(transactions_by_scope, t->scope->transactions, t); - if (t->query) { - LIST_REMOVE(transactions_by_query, t->query->transactions, t); - hashmap_remove(t->query->manager->dns_query_transactions, UINT_TO_PTR(t->id)); + if (t->id != 0) + hashmap_remove(t->scope->manager->dns_query_transactions, UINT_TO_PTR(t->id)); } - if (t->scope) - LIST_REMOVE(transactions_by_scope, t->scope->transactions, t); + while ((q = set_steal_first(t->queries))) + set_remove(q->transactions, t); + + set_free(t->queries); free(t); return NULL; @@ -52,14 +80,25 @@ DnsQueryTransaction* dns_query_transaction_free(DnsQueryTransaction *t) { DEFINE_TRIVIAL_CLEANUP_FUNC(DnsQueryTransaction*, dns_query_transaction_free); -static int dns_query_transaction_new(DnsQuery *q, DnsQueryTransaction **ret, DnsScope *s) { +static void dns_query_transaction_gc(DnsQueryTransaction *t) { + assert(t); + + if (t->block_gc > 0) + return; + + if (set_isempty(t->queries)) + dns_query_transaction_free(t); +} + +static int dns_query_transaction_new(DnsQueryTransaction **ret, DnsScope *s, DnsQuestion *q) { _cleanup_(dns_query_transaction_freep) DnsQueryTransaction *t = NULL; int r; - assert(q); + assert(ret); assert(s); + assert(q); - r = hashmap_ensure_allocated(&q->manager->dns_query_transactions, NULL, NULL); + r = hashmap_ensure_allocated(&s->manager->dns_query_transactions, NULL, NULL); if (r < 0) return r; @@ -67,22 +106,19 @@ static int dns_query_transaction_new(DnsQuery *q, DnsQueryTransaction **ret, Dns if (!t) return -ENOMEM; - t->tcp_fd = -1; + t->question = dns_question_ref(q); do random_bytes(&t->id, sizeof(t->id)); while (t->id == 0 || - hashmap_get(q->manager->dns_query_transactions, UINT_TO_PTR(t->id))); + hashmap_get(s->manager->dns_query_transactions, UINT_TO_PTR(t->id))); - r = hashmap_put(q->manager->dns_query_transactions, UINT_TO_PTR(t->id), t); + r = hashmap_put(s->manager->dns_query_transactions, UINT_TO_PTR(t->id), t); if (r < 0) { t->id = 0; return r; } - LIST_PREPEND(transactions_by_query, q->transactions, t); - t->query = q; - LIST_PREPEND(transactions_by_scope, s->transactions, t); t->scope = s; @@ -98,191 +134,238 @@ static void dns_query_transaction_stop(DnsQueryTransaction *t) { assert(t); t->timeout_event_source = sd_event_source_unref(t->timeout_event_source); - t->tcp_event_source = sd_event_source_unref(t->tcp_event_source); - t->tcp_fd = safe_close(t->tcp_fd); + t->stream = dns_stream_free(t->stream); } -static void dns_query_transaction_set_state(DnsQueryTransaction *t, DnsQueryState state) { +void dns_query_transaction_complete(DnsQueryTransaction *t, DnsQueryState state) { + DnsQuery *q; + Iterator i; + assert(t); + assert(!IN_SET(state, DNS_QUERY_NULL, DNS_QUERY_PENDING)); + assert(IN_SET(t->state, DNS_QUERY_NULL, DNS_QUERY_PENDING)); - if (t->state == state) - return; + /* Note that this call might invalidate the query. Callers + * should hence not attempt to access the query or transaction + * after calling this function. */ + + log_debug("Transaction on scope %s on %s/%s now complete with %s", + dns_protocol_to_string(t->scope->protocol), + t->scope->link ? t->scope->link->name : "*", + t->scope->family == AF_UNSPEC ? "*" : af_to_name(t->scope->family), + dns_query_state_to_string(state)); t->state = state; - if (state != DNS_QUERY_SENT) { - dns_query_transaction_stop(t); - dns_query_finish(t->query); - } + dns_query_transaction_stop(t); + + /* Notify all queries that are interested, but make sure the + * transaction isn't freed while we are still looking at it */ + t->block_gc++; + SET_FOREACH(q, t->queries, i) + dns_query_ready(q); + t->block_gc--; + + dns_query_transaction_gc(t); } -static int on_tcp_ready(sd_event_source *s, int fd, uint32_t revents, void *userdata) { - DnsQueryTransaction *t = userdata; - int r; +static int on_stream_complete(DnsStream *s, int error) { + _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; + DnsQueryTransaction *t; - assert(t); + assert(s); + assert(s->transaction); - if (revents & EPOLLOUT) { - struct iovec iov[2]; - be16_t sz; - ssize_t ss; + /* Copy the data we care about out of the stream before we + * destroy it. */ + t = s->transaction; + p = dns_packet_ref(s->read_packet); - sz = htobe16(t->sent->size); + t->stream = dns_stream_free(t->stream); - iov[0].iov_base = &sz; - iov[0].iov_len = sizeof(sz); - iov[1].iov_base = DNS_PACKET_DATA(t->sent); - iov[1].iov_len = t->sent->size; + if (error != 0) { + dns_query_transaction_complete(t, DNS_QUERY_RESOURCES); + return 0; + } - IOVEC_INCREMENT(iov, 2, t->tcp_written); + t->block_gc++; + dns_query_transaction_process_reply(t, p); + t->block_gc--; - ss = writev(fd, iov, 2); - if (ss < 0) { - if (errno != EINTR && errno != EAGAIN) { - dns_query_transaction_set_state(t, DNS_QUERY_RESOURCES); - return -errno; - } - } else - t->tcp_written += ss; + /* If the response wasn't useful, then complete the transition now */ + if (t->state == DNS_QUERY_PENDING) + dns_query_transaction_complete(t, DNS_QUERY_INVALID_REPLY); - /* Are we done? If so, disable the event source for EPOLLOUT */ - if (t->tcp_written >= sizeof(sz) + t->sent->size) { - r = sd_event_source_set_io_events(s, EPOLLIN); - if (r < 0) { - dns_query_transaction_set_state(t, DNS_QUERY_RESOURCES); - return r; - } - } - } + return 0; +} - if (revents & (EPOLLIN|EPOLLHUP|EPOLLRDHUP)) { +static int dns_query_transaction_open_tcp(DnsQueryTransaction *t) { + _cleanup_close_ int fd = -1; + int r; - if (t->tcp_read < sizeof(t->tcp_read_size)) { - ssize_t ss; + assert(t); - ss = read(fd, (uint8_t*) &t->tcp_read_size + t->tcp_read, sizeof(t->tcp_read_size) - t->tcp_read); - if (ss < 0) { - if (errno != EINTR && errno != EAGAIN) { - dns_query_transaction_set_state(t, DNS_QUERY_RESOURCES); - return -errno; - } - } else if (ss == 0) { - dns_query_transaction_set_state(t, DNS_QUERY_RESOURCES); - return -EIO; - } else - t->tcp_read += ss; - } + if (t->stream) + return 0; - if (t->tcp_read >= sizeof(t->tcp_read_size)) { + if (t->scope->protocol == DNS_PROTOCOL_DNS) + fd = dns_scope_tcp_socket(t->scope, AF_UNSPEC, NULL, 53); + else if (t->scope->protocol == DNS_PROTOCOL_LLMNR) { + + /* When we already received a query to this (but it was truncated), send to its sender address */ + if (t->received) + fd = dns_scope_tcp_socket(t->scope, t->received->family, &t->received->sender, t->received->sender_port); + else { + union in_addr_union address; + int family; + + /* Otherwise, try to talk to the owner of a + * the IP address, in case this is a reverse + * PTR lookup */ + r = dns_question_extract_reverse_address(t->question, &family, &address); + if (r < 0) + return r; + if (r == 0) + return -EINVAL; - if (be16toh(t->tcp_read_size) < DNS_PACKET_HEADER_SIZE) { - dns_query_transaction_set_state(t, DNS_QUERY_INVALID_REPLY); - return -EBADMSG; - } + fd = dns_scope_tcp_socket(t->scope, family, &address, 5355); + } + } else + return -EAFNOSUPPORT; - if (t->tcp_read < sizeof(t->tcp_read_size) + be16toh(t->tcp_read_size)) { - ssize_t ss; + if (fd < 0) + return fd; - if (!t->received) { - r = dns_packet_new(&t->received, be16toh(t->tcp_read_size)); - if (r < 0) { - dns_query_transaction_set_state(t, DNS_QUERY_RESOURCES); - return r; - } - } + r = dns_stream_new(t->scope->manager, &t->stream, t->scope->protocol, fd); + if (r < 0) + return r; - ss = read(fd, - (uint8_t*) DNS_PACKET_DATA(t->received) + t->tcp_read - sizeof(t->tcp_read_size), - sizeof(t->tcp_read_size) + be16toh(t->tcp_read_size) - t->tcp_read); - if (ss < 0) { - if (errno != EINTR && errno != EAGAIN) { - dns_query_transaction_set_state(t, DNS_QUERY_RESOURCES); - return -errno; - } - } else if (ss == 0) { - dns_query_transaction_set_state(t, DNS_QUERY_RESOURCES); - return -EIO; - } else - t->tcp_read += ss; - } + fd = -1; - if (t->tcp_read >= sizeof(t->tcp_read_size) + be16toh(t->tcp_read_size)) { - t->received->size = be16toh(t->tcp_read_size); - dns_query_transaction_reply(t, t->received); - return 0; - } - } + r = dns_stream_write_packet(t->stream, t->sent); + if (r < 0) { + t->stream = dns_stream_free(t->stream); + return r; } + t->received = dns_packet_unref(t->received); + t->stream->complete = on_stream_complete; + t->stream->transaction = t; + + /* The interface index is difficult to determine if we are + * connecting to the local host, hence fill this in right away + * instead of determining it from the socket */ + if (t->scope->link) + t->stream->ifindex = t->scope->link->ifindex; + return 0; } -static int dns_query_transaction_start_tcp(DnsQueryTransaction *t) { +void dns_query_transaction_process_reply(DnsQueryTransaction *t, DnsPacket *p) { int r; assert(t); + assert(p); + assert(t->state == DNS_QUERY_PENDING); - if (t->tcp_fd >= 0) - return 0; + /* Note that this call might invalidate the query. Callers + * should hence not attempt to access the query or transaction + * after calling this function. */ - t->tcp_written = 0; - t->tcp_read = 0; - t->received = dns_packet_unref(t->received); + if (t->scope->protocol == DNS_PROTOCOL_LLMNR) { + assert(t->scope->link); - t->tcp_fd = dns_scope_tcp_socket(t->scope); - if (t->tcp_fd < 0) - return t->tcp_fd; + /* For LLMNR we will not accept any packets from other + * interfaces */ - r = sd_event_add_io(t->query->manager->event, &t->tcp_event_source, t->tcp_fd, EPOLLIN|EPOLLOUT, on_tcp_ready, t); - if (r < 0) { - t->tcp_fd = safe_close(t->tcp_fd); - return r; + if (p->ifindex != t->scope->link->ifindex) + return; + + if (p->family != t->scope->family) + return; + + /* Tentative replies shall be discarded, see RFC 4795, + * 2.1.1 */ + + if (DNS_PACKET_T(p)) + return; } - return 0; -} + if (t->scope->protocol == DNS_PROTOCOL_DNS) { -void dns_query_transaction_reply(DnsQueryTransaction *t, DnsPacket *p) { - int r; + /* For DNS we are fine with accepting packets on any + * interface, but the source IP address must be one of + * a valid DNS server */ - assert(t); - assert(p); + if (!dns_scope_good_dns_server(t->scope, p->family, &p->sender)) + return; - if (t->state != DNS_QUERY_SENT) - return; + if (p->sender_port != 53) + return; + } if (t->received != p) { dns_packet_unref(t->received); t->received = dns_packet_ref(p); } - if (t->tcp_fd >= 0) { + if (p->ipproto == IPPROTO_TCP) { if (DNS_PACKET_TC(p)) { /* Truncated via TCP? Somebody must be fucking with us */ - dns_query_transaction_set_state(t, DNS_QUERY_INVALID_REPLY); + dns_query_transaction_complete(t, DNS_QUERY_INVALID_REPLY); return; } if (DNS_PACKET_ID(p) != t->id) { /* Not the reply to our query? Somebody must be fucking with us */ - dns_query_transaction_set_state(t, DNS_QUERY_INVALID_REPLY); + dns_query_transaction_complete(t, DNS_QUERY_INVALID_REPLY); return; } } if (DNS_PACKET_TC(p)) { /* Response was truncated, let's try again with good old TCP */ - r = dns_query_transaction_start_tcp(t); + r = dns_query_transaction_open_tcp(t); + if (r == -ESRCH) { + /* No servers found? Damn! */ + dns_query_transaction_complete(t, DNS_QUERY_NO_SERVERS); + return; + } if (r < 0) { - dns_query_transaction_set_state(t, DNS_QUERY_RESOURCES); + /* On LLMNR, if we cannot connect to the host, + * we immediately give up */ + if (t->scope->protocol == DNS_PROTOCOL_LLMNR) { + dns_query_transaction_complete(t, DNS_QUERY_RESOURCES); + return; + } + + /* On DNS, couldn't send? Try immediately again, with a new server */ + dns_scope_next_dns_server(t->scope); + + r = dns_query_transaction_go(t); + if (r < 0) { + dns_query_transaction_complete(t, DNS_QUERY_RESOURCES); + return; + } + return; } } + /* Parse and update the cache */ + r = dns_packet_extract(p); + if (r < 0) { + dns_query_transaction_complete(t, DNS_QUERY_INVALID_REPLY); + return; + } + + /* According to RFC 4795, section 2.9. only the RRs from the answer section shall be cached */ + dns_cache_put(&t->scope->cache, p->question, DNS_PACKET_RCODE(p), p->answer, DNS_PACKET_ANCOUNT(p), 0); + if (DNS_PACKET_RCODE(p) == DNS_RCODE_SUCCESS) - dns_query_transaction_set_state(t, DNS_QUERY_SUCCESS); + dns_query_transaction_complete(t, DNS_QUERY_SUCCESS); else - dns_query_transaction_set_state(t, DNS_QUERY_FAILURE); + dns_query_transaction_complete(t, DNS_QUERY_FAILURE); } static int on_transaction_timeout(sd_event_source *s, usec_t usec, void *userdata) { @@ -295,16 +378,16 @@ static int on_transaction_timeout(sd_event_source *s, usec_t usec, void *userdat /* Timeout reached? Try again, with a new server */ dns_scope_next_dns_server(t->scope); - r = dns_query_transaction_start(t); + r = dns_query_transaction_go(t); if (r < 0) - dns_query_transaction_set_state(t, DNS_QUERY_RESOURCES); + dns_query_transaction_complete(t, DNS_QUERY_RESOURCES); return 0; } static int dns_query_make_packet(DnsQueryTransaction *t) { _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; - unsigned n; + unsigned n, added = 0; int r; assert(t); @@ -312,17 +395,28 @@ static int dns_query_make_packet(DnsQueryTransaction *t) { if (t->sent) return 0; - r = dns_packet_new_query(&p, 0); + r = dns_packet_new_query(&p, t->scope->protocol, 0); if (r < 0) return r; - for (n = 0; n < t->query->n_keys; n++) { - r = dns_packet_append_key(p, &t->query->keys[n], NULL); + for (n = 0; n < t->question->n_keys; n++) { + r = dns_scope_good_key(t->scope, t->question->keys[n]); + if (r < 0) + return r; + if (r == 0) + continue; + + r = dns_packet_append_key(p, t->question->keys[n], NULL); if (r < 0) return r; + + added++; } - DNS_PACKET_HEADER(p)->qdcount = htobe16(t->query->n_keys); + if (added <= 0) + return -EDOM; + + DNS_PACKET_HEADER(p)->qdcount = htobe16(added); DNS_PACKET_HEADER(p)->id = t->id; t->sent = p; @@ -331,113 +425,309 @@ static int dns_query_make_packet(DnsQueryTransaction *t) { return 0; } -int dns_query_transaction_start(DnsQueryTransaction *t) { +static int dns_query_transaction_go(DnsQueryTransaction *t) { + bool had_stream; int r; assert(t); + had_stream = !!t->stream; + dns_query_transaction_stop(t); - if (t->n_attempts >= ATTEMPTS_MAX) { - dns_query_transaction_set_state(t, DNS_QUERY_ATTEMPTS_MAX); + log_debug("Beginning transaction on scope %s on %s/%s", + dns_protocol_to_string(t->scope->protocol), + t->scope->link ? t->scope->link->name : "*", + t->scope->family == AF_UNSPEC ? "*" : af_to_name(t->scope->family)); + + if (t->n_attempts >= TRANSACTION_ATTEMPTS_MAX(t)) { + dns_query_transaction_complete(t, DNS_QUERY_ATTEMPTS_MAX); return 0; } + + if (t->scope->protocol == DNS_PROTOCOL_LLMNR && had_stream) { + /* If we already tried via a stream, then we don't + * retry on LLMNR. See RFC 4795, Section 2.7. */ + dns_query_transaction_complete(t, DNS_QUERY_ATTEMPTS_MAX); + return 0; + } + t->n_attempts++; + t->received = dns_packet_unref(t->received); + t->cached = dns_answer_unref(t->cached); + t->cached_rcode = 0; - r = dns_query_make_packet(t); + /* First, let's try the cache */ + dns_cache_prune(&t->scope->cache); + r = dns_cache_lookup(&t->scope->cache, t->question, &t->cached_rcode, &t->cached); if (r < 0) return r; + if (r > 0) { + if (t->cached_rcode == DNS_RCODE_SUCCESS) + dns_query_transaction_complete(t, DNS_QUERY_SUCCESS); + else + dns_query_transaction_complete(t, DNS_QUERY_FAILURE); + return 0; + } - /* Try via UDP, and if that fails due to large size try via TCP */ - r = dns_scope_send(t->scope, t->sent); - if (r == -EMSGSIZE) - r = dns_query_transaction_start_tcp(t); + /* Otherwise, we need to ask the network */ + r = dns_query_make_packet(t); + if (r == -EDOM) { + /* Not the right request to make on this network? + * (i.e. an A request made on IPv6 or an AAAA request + * made on IPv4, on LLMNR or mDNS.) */ + dns_query_transaction_complete(t, DNS_QUERY_NO_SERVERS); + return 0; + } + if (r < 0) + return r; + if (t->scope->protocol == DNS_PROTOCOL_LLMNR && + (dns_question_endswith(t->question, "in-addr.arpa") > 0 || + dns_question_endswith(t->question, "ip6.arpa") > 0)) { + + /* RFC 4795, Section 2.4. says reverse lookups shall + * always be made via TCP on LLMNR */ + r = dns_query_transaction_open_tcp(t); + } else { + /* Try via UDP, and if that fails due to large size try via TCP */ + r = dns_scope_send(t->scope, t->sent); + if (r == -EMSGSIZE) + r = dns_query_transaction_open_tcp(t); + } if (r == -ESRCH) { - dns_query_transaction_set_state(t, DNS_QUERY_NO_SERVERS); + /* No servers to send this to? */ + dns_query_transaction_complete(t, DNS_QUERY_NO_SERVERS); return 0; } if (r < 0) { /* Couldn't send? Try immediately again, with a new server */ dns_scope_next_dns_server(t->scope); - return dns_query_transaction_start(t); + return dns_query_transaction_go(t); } - r = sd_event_add_time(t->query->manager->event, &t->timeout_event_source, CLOCK_MONOTONIC, now(CLOCK_MONOTONIC) + TRANSACTION_TIMEOUT_USEC, 0, on_transaction_timeout, t); + r = sd_event_add_time(t->scope->manager->event, &t->timeout_event_source, CLOCK_MONOTONIC, now(CLOCK_MONOTONIC) + TRANSACTION_TIMEOUT_USEC(t), 0, on_transaction_timeout, t); if (r < 0) return r; - dns_query_transaction_set_state(t, DNS_QUERY_SENT); + t->state = DNS_QUERY_PENDING; return 1; } DnsQuery *dns_query_free(DnsQuery *q) { - unsigned n; + DnsQueryTransaction *t; if (!q) return NULL; sd_bus_message_unref(q->request); - dns_packet_unref(q->received); + + dns_question_unref(q->question); + dns_answer_unref(q->answer); + sd_event_source_unref(q->timeout_event_source); - while (q->transactions) - dns_query_transaction_free(q->transactions); + while ((t = set_steal_first(q->transactions))) { + set_remove(t->queries, q); + dns_query_transaction_gc(t); + } + + set_free(q->transactions); - if (q->manager) + if (q->manager) { LIST_REMOVE(queries, q->manager->dns_queries, q); + q->manager->n_dns_queries--; + } - for (n = 0; n < q->n_keys; n++) - free(q->keys[n].name); - free(q->keys); free(q); return NULL; } -int dns_query_new(Manager *m, DnsQuery **ret, DnsResourceKey *keys, unsigned n_keys) { +int dns_query_new(Manager *m, DnsQuery **ret, DnsQuestion *question) { _cleanup_(dns_query_freep) DnsQuery *q = NULL; - DnsScope *s, *first = NULL; - DnsScopeMatch found = DNS_SCOPE_NO; - const char *name = NULL; - int n, r; + unsigned i; + int r; assert(m); + assert(question); - if (n_keys <= 0 || n_keys >= 65535) - return -EINVAL; + r = dns_question_is_valid(question); + if (r < 0) + return r; - assert(keys); + if (m->n_dns_queries >= QUERIES_MAX) + return -EBUSY; q = new0(DnsQuery, 1); if (!q) return -ENOMEM; - q->keys = new(DnsResourceKey, n_keys); - if (!q->keys) - return -ENOMEM; + q->question = dns_question_ref(question); - for (q->n_keys = 0; q->n_keys < n_keys; q->n_keys++) { - q->keys[q->n_keys].class = keys[q->n_keys].class; - q->keys[q->n_keys].type = keys[q->n_keys].type; - q->keys[q->n_keys].name = strdup(keys[q->n_keys].name); - if (!q->keys[q->n_keys].name) - return -ENOMEM; + for (i = 0; i < question->n_keys; i++) { + _cleanup_free_ char *p; + + r = dns_resource_key_to_string(question->keys[i], &p); + if (r < 0) + return r; - if (!name) - name = q->keys[q->n_keys].name; - else if (!dns_name_equal(name, q->keys[q->n_keys].name)) - return -EINVAL; + log_debug("Looking up RR for %s", p); } LIST_PREPEND(queries, m->dns_queries, q); + m->n_dns_queries++; q->manager = m; - LIST_FOREACH(scopes, s, m->dns_scopes) { + if (ret) + *ret = q; + q = NULL; + + return 0; +} + +static void dns_query_stop(DnsQuery *q) { + DnsQueryTransaction *t; + + assert(q); + + q->timeout_event_source = sd_event_source_unref(q->timeout_event_source); + + while ((t = set_steal_first(q->transactions))) { + set_remove(t->queries, q); + dns_query_transaction_gc(t); + } +} + +static void dns_query_complete(DnsQuery *q, DnsQueryState state) { + assert(q); + assert(!IN_SET(state, DNS_QUERY_NULL, DNS_QUERY_PENDING)); + assert(IN_SET(q->state, DNS_QUERY_NULL, DNS_QUERY_PENDING)); + + /* 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_QUERY_TIMEOUT); + return 0; +} + +static int dns_query_add_transaction(DnsQuery *q, DnsScope *s, DnsResourceKey *key) { + _cleanup_(dns_question_unrefp) DnsQuestion *question = NULL; + DnsQueryTransaction *t; + int r; + + assert(q); + + r = set_ensure_allocated(&q->transactions, NULL, NULL); + if (r < 0) + return r; + + if (key) { + question = dns_question_new(1); + if (!question) + return -ENOMEM; + + r = dns_question_add(question, key); + if (r < 0) + return r; + } else + question = dns_question_ref(q->question); + + LIST_FOREACH(transactions_by_scope, t, s->transactions) + if (dns_question_is_superset(t->question, question)) + break; + + if (!t) { + r = dns_query_transaction_new(&t, s, question); + if (r < 0) + return r; + } + + r = set_ensure_allocated(&t->queries, NULL, NULL); + if (r < 0) + goto fail; + + r = set_put(t->queries, q); + if (r < 0) + goto fail; + + r = set_put(q->transactions, t); + if (r < 0) { + set_remove(t->queries, q); + goto fail; + } + + return 0; + +fail: + dns_query_transaction_gc(t); + return r; +} + +static int dns_query_add_transaction_split(DnsQuery *q, DnsScope *s) { + int r; + + assert(q); + assert(s); + + if (s->protocol == DNS_PROTOCOL_MDNS) { + r = dns_query_add_transaction(q, s, NULL); + if (r < 0) + return r; + } else { + unsigned i; + + /* On DNS and LLMNR we can only send a single + * question per datagram, hence issue multiple + * transactions. */ + + 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; + } + } + + return 0; +} + +int dns_query_go(DnsQuery *q) { + DnsScopeMatch found = DNS_SCOPE_NO; + DnsScope *s, *first = NULL; + DnsQueryTransaction *t; + const char *name; + Iterator i; + int r; + + assert(q); + + if (q->state != DNS_QUERY_NULL) + return 0; + + assert(q->question); + assert(q->question->n_keys > 0); + + name = DNS_RESOURCE_KEY_NAME(q->question->keys[0]); + + LIST_FOREACH(scopes, s, q->manager->dns_scopes) { DnsScopeMatch match; - match = dns_scope_test(s, name); + match = dns_scope_good_domain(s, name); if (match < 0) return match; @@ -458,130 +748,140 @@ int dns_query_new(Manager *m, DnsQuery **ret, DnsResourceKey *keys, unsigned n_k } if (found == DNS_SCOPE_NO) - return -ENETDOWN; + return -ESRCH; - r = dns_query_transaction_new(q, NULL, first); + r = dns_query_add_transaction_split(q, first); if (r < 0) return r; - n = 1; LIST_FOREACH(scopes, s, first->scopes_next) { DnsScopeMatch match; - match = dns_scope_test(s, name); + match = dns_scope_good_domain(s, name); if (match < 0) return match; if (match != found) continue; - r = dns_query_transaction_new(q, NULL, s); + r = dns_query_add_transaction_split(q, s); if (r < 0) return r; - - n++; } - if (ret) - *ret = q; - q = NULL; - - return n; -} - -static void dns_query_set_state(DnsQuery *q, DnsQueryState state) { - assert(q); - - if (q->state == state) - return; - - q->state = state; - - if (state == DNS_QUERY_SENT) - return; - - q->timeout_event_source = sd_event_source_unref(q->timeout_event_source); - - while (q->transactions) - dns_query_transaction_free(q->transactions); - - 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_set_state(q, DNS_QUERY_TIMEOUT); - return 0; -} - -int dns_query_start(DnsQuery *q) { - DnsQueryTransaction *t; - int r; - - assert(q); - assert(q->state == DNS_QUERY_NULL); - - if (!q->transactions) - return -ENETDOWN; + q->answer = dns_answer_unref(q->answer); + q->answer_ifindex = 0; + q->answer_rcode = 0; r = sd_event_add_time(q->manager->event, &q->timeout_event_source, CLOCK_MONOTONIC, now(CLOCK_MONOTONIC) + QUERY_TIMEOUT_USEC, 0, on_query_timeout, q); if (r < 0) goto fail; - dns_query_set_state(q, DNS_QUERY_SENT); + q->state = DNS_QUERY_PENDING; + q->block_ready++; - LIST_FOREACH(transactions_by_query, t, q->transactions) { - - r = dns_query_transaction_start(t); - if (r < 0) - goto fail; - - if (q->state != DNS_QUERY_SENT) - break; + SET_FOREACH(t, q->transactions, i) { + if (t->state == DNS_QUERY_NULL) { + r = dns_query_transaction_go(t); + if (r < 0) + goto fail; + } } - return 0; + q->block_ready--; + dns_query_ready(q); -fail: - while (q->transactions) - dns_query_transaction_free(q->transactions); + return 1; +fail: + dns_query_stop(q); return r; } -void dns_query_finish(DnsQuery *q) { +void dns_query_ready(DnsQuery *q) { DnsQueryTransaction *t; DnsQueryState state = DNS_QUERY_NO_SERVERS; - DnsPacket *received = NULL; + _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL; + int rcode = 0; + DnsScope *scope = NULL; + bool pending = false; + Iterator i; assert(q); + assert(IN_SET(q->state, DNS_QUERY_NULL, DNS_QUERY_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 (q->state != DNS_QUERY_SENT) + if (q->block_ready > 0) return; - LIST_FOREACH(transactions_by_query, t, q->transactions) { + SET_FOREACH(t, q->transactions, i) { - /* One of the transactions is still going on, let's wait for it */ - if (t->state == DNS_QUERY_SENT || t->state == DNS_QUERY_NULL) - return; + /* If we found a successful answer, ignore all answers from other scopes */ + if (state == DNS_QUERY_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_QUERY_PENDING, DNS_QUERY_NULL)) { + pending = true; + continue; + } - /* One of the transactions is successful, let's use it */ + /* One of the transactions is successful, let's use + * it, and copy its data out */ if (t->state == DNS_QUERY_SUCCESS) { - q->received = dns_packet_ref(t->received); - dns_query_set_state(q, DNS_QUERY_SUCCESS); - return; + DnsAnswer *a; + + if (t->received) { + rcode = DNS_PACKET_RCODE(t->received); + a = t->received->answer; + } else { + rcode = t->cached_rcode; + a = t->cached; + } + + if (state == DNS_QUERY_SUCCESS) { + DnsAnswer *merged; + + merged = dns_answer_merge(answer, a); + if (!merged) { + dns_query_complete(q, DNS_QUERY_RESOURCES); + return; + } + + dns_answer_unref(answer); + answer = merged; + } else { + dns_answer_unref(answer); + answer = dns_answer_ref(a); + } + + scope = t->scope; + state = DNS_QUERY_SUCCESS; + continue; } /* One of the transactions has failed, let's see * whether we find anything better, but if not, return - * its response packet */ - if (t->state == DNS_QUERY_FAILURE) { - received = t->received; + * its response data */ + if (state != DNS_QUERY_SUCCESS && t->state == DNS_QUERY_FAILURE) { + DnsAnswer *a; + + if (t->received) { + rcode = DNS_PACKET_RCODE(t->received); + a = t->received->answer; + } else { + rcode = t->cached_rcode; + a = t->cached; + } + + dns_answer_unref(answer); + answer = dns_answer_ref(a); + + scope = t->scope; state = DNS_QUERY_FAILURE; continue; } @@ -590,8 +890,65 @@ void dns_query_finish(DnsQuery *q) { state = t->state; } - if (state == DNS_QUERY_FAILURE) - q->received = dns_packet_ref(received); + if (pending) { - dns_query_set_state(q, state); + /* If so far we weren't successful, and there's + * something still pending, then wait for it */ + if (state != DNS_QUERY_SUCCESS) + 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_QUERY_PENDING, DNS_QUERY_NULL)) + return; + } + } + + if (IN_SET(state, DNS_QUERY_SUCCESS, DNS_QUERY_FAILURE)) { + q->answer = dns_answer_ref(answer); + q->answer_rcode = rcode; + q->answer_ifindex = (scope && scope->link) ? scope->link->ifindex : 0; + } + + dns_query_complete(q, state); } + +int dns_query_cname_redirect(DnsQuery *q, const char *name) { + _cleanup_(dns_question_unrefp) DnsQuestion *nq = NULL; + int r; + + assert(q); + + if (q->n_cname_redirects > CNAME_MAX) + return -ELOOP; + + r = dns_question_cname_redirect(q->question, name, &nq); + if (r < 0) + return r; + + dns_question_unref(q->question); + q->question = nq; + nq = NULL; + + q->n_cname_redirects++; + + dns_query_stop(q); + q->state = DNS_QUERY_NULL; + + return 0; +} + +static const char* const dns_query_state_table[_DNS_QUERY_STATE_MAX] = { + [DNS_QUERY_NULL] = "null", + [DNS_QUERY_PENDING] = "pending", + [DNS_QUERY_FAILURE] = "failure", + [DNS_QUERY_SUCCESS] = "success", + [DNS_QUERY_NO_SERVERS] = "no-servers", + [DNS_QUERY_TIMEOUT] = "timeout", + [DNS_QUERY_ATTEMPTS_MAX] = "attempts-max", + [DNS_QUERY_INVALID_REPLY] = "invalid-reply", + [DNS_QUERY_RESOURCES] = "resources", + [DNS_QUERY_ABORTED] = "aborted", +}; +DEFINE_STRING_TABLE_LOOKUP(dns_query_state, DnsQueryState);