along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
+#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) {
dns_packet_unref(t->received);
dns_answer_unref(t->cached);
- sd_event_source_unref(t->tcp_event_source);
- safe_close(t->tcp_fd);
+ dns_stream_free(t->stream);
if (t->scope) {
LIST_REMOVE(transactions_by_scope, t->scope->transactions, t);
if (!t)
return -ENOMEM;
- t->tcp_fd = -1;
t->question = dns_question_ref(q);
do
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);
}
void dns_query_transaction_complete(DnsQueryTransaction *t, DnsQueryState state) {
* 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;
dns_query_transaction_stop(t);
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;
-
- assert(t);
-
- if (revents & EPOLLOUT) {
- struct iovec iov[2];
- be16_t sz;
- ssize_t ss;
+static int on_stream_complete(DnsStream *s, int error) {
+ _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
+ DnsQueryTransaction *t;
- sz = htobe16(t->sent->size);
+ assert(s);
+ assert(s->transaction);
- 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;
+ /* Copy the data we care about out of the stream before we
+ * destroy it. */
+ t = s->transaction;
+ p = dns_packet_ref(s->read_packet);
- IOVEC_INCREMENT(iov, 2, t->tcp_written);
+ t->stream = dns_stream_free(t->stream);
- ss = writev(fd, iov, 2);
- if (ss < 0) {
- if (errno != EINTR && errno != EAGAIN) {
- dns_query_transaction_complete(t, DNS_QUERY_RESOURCES);
- return -errno;
- }
- } else
- t->tcp_written += ss;
-
- /* 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_complete(t, DNS_QUERY_RESOURCES);
- return r;
- }
- }
+ if (error != 0) {
+ dns_query_transaction_complete(t, DNS_QUERY_RESOURCES);
+ return 0;
}
- if (revents & (EPOLLIN|EPOLLHUP|EPOLLRDHUP)) {
-
- if (t->tcp_read < sizeof(t->tcp_read_size)) {
- ssize_t ss;
-
- 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_complete(t, DNS_QUERY_RESOURCES);
- return -errno;
- }
- } else if (ss == 0) {
- dns_query_transaction_complete(t, DNS_QUERY_RESOURCES);
- return -EIO;
- } else
- t->tcp_read += ss;
- }
-
- if (t->tcp_read >= sizeof(t->tcp_read_size)) {
-
- if (be16toh(t->tcp_read_size) < DNS_PACKET_HEADER_SIZE) {
- dns_query_transaction_complete(t, DNS_QUERY_INVALID_REPLY);
- return -EBADMSG;
- }
-
- if (t->tcp_read < sizeof(t->tcp_read_size) + be16toh(t->tcp_read_size)) {
- ssize_t ss;
-
- if (!t->received) {
- r = dns_packet_new(&t->received, t->scope->protocol, be16toh(t->tcp_read_size));
- if (r < 0) {
- dns_query_transaction_complete(t, DNS_QUERY_RESOURCES);
- 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_complete(t, DNS_QUERY_RESOURCES);
- return -errno;
- }
- } else if (ss == 0) {
- dns_query_transaction_complete(t, DNS_QUERY_RESOURCES);
- return -EIO;
- } else
- t->tcp_read += ss;
- }
+ t->block_gc++;
+ dns_query_transaction_process_reply(t, p);
+ t->block_gc--;
- 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_process_reply(t, t->received);
- return 0;
- }
- }
- }
+ /* 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);
return 0;
}
static int dns_query_transaction_open_tcp(DnsQueryTransaction *t) {
+ _cleanup_close_ int fd = -1;
int r;
assert(t);
+ if (t->stream)
+ return 0;
+
if (t->scope->protocol == DNS_PROTOCOL_DNS)
- return -ENOTSUP;
+ 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 (t->tcp_fd >= 0)
- return 0;
+ fd = dns_scope_tcp_socket(t->scope, family, &address, 5355);
+ }
+ } else
+ return -EAFNOSUPPORT;
- t->tcp_written = 0;
- t->tcp_read = 0;
- t->received = dns_packet_unref(t->received);
+ if (fd < 0)
+ return fd;
+
+ r = dns_stream_new(t->scope->manager, &t->stream, t->scope->protocol, fd);
+ if (r < 0)
+ return r;
- t->tcp_fd = dns_scope_tcp_socket(t->scope);
- if (t->tcp_fd < 0)
- return t->tcp_fd;
+ fd = -1;
- r = sd_event_add_io(t->scope->manager->event, &t->tcp_event_source, t->tcp_fd, EPOLLIN|EPOLLOUT, on_tcp_ready, t);
+ r = dns_stream_write_packet(t->stream, t->sent);
if (r < 0) {
- t->tcp_fd = safe_close(t->tcp_fd);
+ 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;
}
* should hence not attempt to access the query or transaction
* after calling this function. */
+ if (t->scope->protocol == DNS_PROTOCOL_LLMNR) {
+ assert(t->scope->link);
+
+ /* For LLMNR we will not accept any packets from other
+ * interfaces */
+
+ 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;
+ }
+
+ if (t->scope->protocol == DNS_PROTOCOL_DNS) {
+
+ /* For DNS we are fine with accepting packets on any
+ * interface, but the source IP address must be one of
+ * a valid DNS server */
+
+ if (!dns_scope_good_dns_server(t->scope, p->family, &p->sender))
+ 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_complete(t, DNS_QUERY_INVALID_REPLY);
return;
}
if (r < 0) {
- /* Couldn't send? Try immediately again, with a new server */
+ /* 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);
return;
}
- dns_cache_put(&t->scope->cache, p->question, DNS_PACKET_RCODE(p), p->answer, 0);
+ /* 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_complete(t, DNS_QUERY_SUCCESS);
}
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) {
+ 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;
}
if (r < 0)
return r;
- /* 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)
+ 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) {
/* No servers to send this to? */
dns_query_transaction_complete(t, DNS_QUERY_NO_SERVERS);
return dns_query_transaction_go(t);
}
- r = sd_event_add_time(t->scope->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;
q->question = dns_question_ref(question);
for (i = 0; i < question->n_keys; i++) {
- log_debug("Looking up RR for %s %s %s",
- strna(dns_class_to_string(question->keys[i]->class)),
- strna(dns_type_to_string(question->keys[i]->type)),
- DNS_RESOURCE_KEY_NAME(question->keys[i]));
+ _cleanup_free_ char *p;
+
+ r = dns_resource_key_to_string(question->keys[i], &p);
+ if (r < 0)
+ return r;
+
+ log_debug("Looking up RR for %s", p);
}
LIST_PREPEND(queries, m->dns_queries, q);
_cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
int rcode = 0;
DnsScope *scope = NULL;
+ bool pending = false;
Iterator i;
assert(q);
if (state == DNS_QUERY_SUCCESS && t->scope != scope)
continue;
- /* One of the transactions is still going on, let's wait for it */
- if (t->state == DNS_QUERY_PENDING || t->state == DNS_QUERY_NULL)
- return;
+ /* 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, and copy its data out */
state = t->state;
}
+ if (pending) {
+
+ /* 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;
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);