+/* SPDX-License-Identifier: LGPL-2.1+ */
/***
This file is part of systemd.
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
-#include <sd-messages.h>
+#include "sd-messages.h"
#include "af-list.h"
#include "alloc-util.h"
#include "string-table.h"
#define TRANSACTIONS_MAX 4096
+#define TRANSACTION_TCP_TIMEOUT_USEC (10U*USEC_PER_SEC)
static void dns_transaction_reset_answer(DnsTransaction *t) {
assert(t);
static void dns_transaction_close_connection(DnsTransaction *t) {
assert(t);
- t->stream = dns_stream_free(t->stream);
+ if (t->stream) {
+ /* Let's detach the stream from our transaction, in case something else keeps a reference to it. */
+ t->stream->complete = NULL;
+ t->stream->on_packet = NULL;
+ t->stream->transaction = NULL;
+ t->stream = dns_stream_unref(t->stream);
+ }
+
t->dns_udp_event_source = sd_event_source_unref(t->dns_udp_event_source);
t->dns_udp_fd = safe_close(t->dns_udp_fd);
}
dns_answer_unref(t->validated_keys);
dns_resource_key_unref(t->key);
- free(t);
- return NULL;
+ return mfree(t);
}
DEFINE_TRIVIAL_CLEANUP_FUNC(DnsTransaction*, dns_transaction_free);
return -EOPNOTSUPP;
/* We only support the IN class */
- if (key->class != DNS_CLASS_IN && key->class != DNS_CLASS_ANY)
+ if (!IN_SET(key->class, DNS_CLASS_IN, DNS_CLASS_ANY))
return -EOPNOTSUPP;
if (hashmap_size(s->manager->dns_transactions) >= TRANSACTIONS_MAX)
t->answer_nsec_ttl = (uint32_t) -1;
t->key = dns_resource_key_ref(key);
t->current_feature_level = _DNS_SERVER_FEATURE_LEVEL_INVALID;
+ t->clamp_feature_level = _DNS_SERVER_FEATURE_LEVEL_INVALID;
t->id = pick_new_id(s->manager);
dns_resource_key_to_string(t->key, key_str, sizeof key_str);
log_struct(LOG_NOTICE,
- LOG_MESSAGE_ID(SD_MESSAGE_DNSSEC_FAILURE),
+ "MESSAGE_ID=" SD_MESSAGE_DNSSEC_FAILURE_STR,
LOG_MESSAGE("DNSSEC validation failed for question %s: %s", key_str, dnssec_result_to_string(t->answer_dnssec_result)),
"DNS_TRANSACTION=%" PRIu16, t->id,
"DNS_QUESTION=%s", key_str,
SET_FOREACH_MOVE(z, t->notify_zone_items_done, t->notify_zone_items)
dns_zone_item_notify(z);
SWAP_TWO(t->notify_zone_items, t->notify_zone_items_done);
+ if (t->probing)
+ (void) dns_scope_announce(t->scope, false);
SET_FOREACH_MOVE(d, t->notify_transactions_done, t->notify_transactions)
dns_transaction_notify(d, t);
assert(t);
assert(t->scope->protocol == DNS_PROTOCOL_DNS);
+ /* Pick a DNS server and a feature level for it. */
+
server = dns_scope_get_dns_server(t->scope);
if (!server)
return -ESRCH;
+ /* If we changed the server invalidate the feature level clamping, as the new server might have completely
+ * different properties. */
+ if (server != t->server)
+ t->clamp_feature_level = _DNS_SERVER_FEATURE_LEVEL_INVALID;
+
t->current_feature_level = dns_server_possible_feature_level(server);
+ /* Clamp the feature level if that is requested. */
+ if (t->clamp_feature_level != _DNS_SERVER_FEATURE_LEVEL_INVALID &&
+ t->current_feature_level > t->clamp_feature_level)
+ t->current_feature_level = t->clamp_feature_level;
+
+ log_debug("Using feature level %s for transaction %u.", dns_server_feature_level_to_string(t->current_feature_level), t->id);
+
if (server == t->server)
return 0;
dns_server_unref(t->server);
t->server = dns_server_ref(server);
+ log_debug("Using DNS server %s for transaction %u.", dns_server_string(t->server), t->id);
+
return 1;
}
-static void dns_transaction_retry(DnsTransaction *t) {
+static void dns_transaction_retry(DnsTransaction *t, bool next_server) {
int r;
assert(t);
log_debug("Retrying transaction %" PRIu16 ".", t->id);
/* Before we try again, switch to a new server. */
- dns_scope_next_dns_server(t->scope);
+ if (next_server)
+ dns_scope_next_dns_server(t->scope);
r = dns_transaction_go(t);
if (r < 0) {
}
static int dns_transaction_maybe_restart(DnsTransaction *t) {
+ int r;
+
assert(t);
+ /* Returns > 0 if the transaction was restarted, 0 if not */
+
if (!t->server)
return 0;
log_debug("Server feature level is now lower than when we began our transaction. Restarting with new ID.");
dns_transaction_shuffle_id(t);
- return dns_transaction_go(t);
+
+ r = dns_transaction_go(t);
+ if (r < 0)
+ return r;
+
+ return 1;
}
static int on_stream_complete(DnsStream *s, int error) {
t = s->transaction;
p = dns_packet_ref(s->read_packet);
- t->stream = dns_stream_free(t->stream);
+ dns_transaction_close_connection(t);
if (ERRNO_IS_DISCONNECT(error)) {
usec_t usec;
assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &usec) >= 0);
dns_server_packet_lost(t->server, IPPROTO_TCP, t->current_feature_level, usec - t->start_usec);
- dns_transaction_retry(t);
+ dns_transaction_retry(t, true);
return 0;
}
if (error != 0) {
r = dns_stream_write_packet(t->stream, t->sent);
if (r < 0) {
- t->stream = dns_stream_free(t->stream);
+ t->stream = dns_stream_unref(t->stream);
return r;
}
/* 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;
+ t->stream->ifindex = dns_scope_ifindex(t->scope);
dns_transaction_reset_answer(t);
if (!IN_SET(t->scope->protocol, DNS_PROTOCOL_DNS, DNS_PROTOCOL_LLMNR))
return;
+ /* Caching disabled? */
+ if (!t->scope->manager->enable_cache)
+ return;
+
/* We never cache if this packet is from the local host, under
* the assumption that a locally running DNS server would
* cache this anyway, and probably knows better when to flush
return 0;
case DNS_TRANSACTION_RCODE_FAILURE:
- if (dt->answer_rcode != DNS_RCODE_NXDOMAIN) {
+ if (!IN_SET(dt->answer_rcode, DNS_RCODE_NXDOMAIN, DNS_RCODE_SERVFAIL)) {
log_debug("Auxiliary DNSSEC RR query failed with rcode=%s.", dns_rcode_to_string(dt->answer_rcode));
goto fail;
}
- /* Fall-through: NXDOMAIN is good enough for us. This is because some DNS servers erronously
- * return NXDOMAIN for empty non-terminals (Akamai...), and we need to handle that nicely, when
- * asking for parent SOA or similar RRs to make unsigned proofs. */
+ /* Fall-through: NXDOMAIN/SERVFAIL is good enough for us. This is because some DNS servers
+ * erronously return NXDOMAIN/SERVFAIL for empty non-terminals (Akamai...) or missing DS
+ * records (Facebook), and we need to handle that nicely, when asking for parent SOA or similar
+ * RRs to make unsigned proofs. */
case DNS_TRANSACTION_SUCCESS:
/* All good. */
* should hence not attempt to access the query or transaction
* after calling this function. */
- log_debug("Processing incoming packet on transaction %" PRIu16".", t->id);
+ log_debug("Processing incoming packet on transaction %" PRIu16". (rcode=%s)", t->id, dns_rcode_to_string(DNS_PACKET_RCODE(p)));
switch (t->scope->protocol) {
case DNS_PROTOCOL_LLMNR:
- assert(t->scope->link);
-
- /* For LLMNR we will not accept any packets from other
- * interfaces */
+ /* For LLMNR we will not accept any packets from other interfaces */
- if (p->ifindex != t->scope->link->ifindex)
+ if (p->ifindex != dns_scope_ifindex(t->scope))
return;
if (p->family != t->scope->family)
break;
case DNS_PROTOCOL_MDNS:
- assert(t->scope->link);
-
/* For mDNS we will not accept any packets from other interfaces */
- if (p->ifindex != t->scope->link->ifindex)
+
+ if (p->ifindex != dns_scope_ifindex(t->scope))
return;
if (p->family != t->scope->family)
if (IN_SET(DNS_PACKET_RCODE(p), DNS_RCODE_FORMERR, DNS_RCODE_SERVFAIL, DNS_RCODE_NOTIMP)) {
/* Request failed, immediately try again with reduced features */
- log_debug("Server returned error: %s", dns_rcode_to_string(DNS_PACKET_RCODE(p)));
- dns_server_packet_failed(t->server, t->current_feature_level);
- dns_transaction_retry(t);
+ if (t->current_feature_level <= DNS_SERVER_FEATURE_LEVEL_UDP) {
+ /* This was already at UDP feature level? If so, it doesn't make sense to downgrade
+ * this transaction anymore, hence let's process the response, and accept the
+ * rcode. Note that we don't retry on TCP, since that's a suitable way to mitigate
+ * packet loss, but is not going to give us better rcodes should we actually have
+ * managed to get them already at UDP level. */
+
+ log_debug("Server returned error: %s", dns_rcode_to_string(DNS_PACKET_RCODE(p)));
+ break;
+ }
+
+ /* Reduce this feature level by one and try again. */
+ t->clamp_feature_level = t->current_feature_level - 1;
+
+ log_debug("Server returned error %s, retrying transaction with reduced feature level %s.",
+ dns_rcode_to_string(DNS_PACKET_RCODE(p)),
+ dns_server_feature_level_to_string(t->clamp_feature_level));
+
+ dns_transaction_retry(t, false /* use the same server */);
return;
- } else if (DNS_PACKET_TC(p))
+ }
+
+ if (DNS_PACKET_RCODE(p) == DNS_RCODE_REFUSED) {
+ /* This server refused our request? If so, try again, use a different server */
+ log_debug("Server returned REFUSED, switching servers, and retrying.");
+ dns_transaction_retry(t, true /* pick a new server */);
+ return;
+ }
+
+ if (DNS_PACKET_TC(p))
dns_server_packet_truncated(t->server, t->current_feature_level);
break;
goto fail;
/* On DNS, couldn't send? Try immediately again, with a new server */
- dns_transaction_retry(t);
+ dns_transaction_retry(t, true);
}
return;
return;
}
- /* Report that the OPT RR was missing */
if (t->server) {
+ /* Report that we successfully received a valid packet with a good rcode after we initially got a bad
+ * rcode and subsequently downgraded the protocol */
+
+ if (IN_SET(DNS_PACKET_RCODE(p), DNS_RCODE_SUCCESS, DNS_RCODE_NXDOMAIN) &&
+ t->clamp_feature_level != _DNS_SERVER_FEATURE_LEVEL_INVALID)
+ dns_server_packet_rcode_downgrade(t->server, t->clamp_feature_level);
+
+ /* Report that the OPT RR was missing */
if (!p->opt)
dns_server_packet_bad_opt(t->server, t->current_feature_level);
+ /* Report that we successfully received a packet */
dns_server_packet_received(t->server, p->ipproto, t->current_feature_level, ts - t->start_usec, p->size);
}
if (r > 0) /* Transaction got restarted... */
return;
- if (IN_SET(t->scope->protocol, DNS_PROTOCOL_DNS, DNS_PROTOCOL_LLMNR)) {
+ if (IN_SET(t->scope->protocol, DNS_PROTOCOL_DNS, DNS_PROTOCOL_LLMNR, DNS_PROTOCOL_MDNS)) {
- /* Only consider responses with equivalent query section to the request */
- r = dns_packet_is_reply_for(p, t->key);
- if (r < 0)
- goto fail;
- if (r == 0) {
- dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
- return;
+ /* When dealing with protocols other than mDNS only consider responses with
+ * equivalent query section to the request. For mDNS this check doesn't make
+ * sense, because the section 6 of RFC6762 states that "Multicast DNS responses MUST NOT
+ * contain any questions in the Question Section". */
+ if (t->scope->protocol != DNS_PROTOCOL_MDNS) {
+ r = dns_packet_is_reply_for(p, t->key);
+ if (r < 0)
+ goto fail;
+ if (r == 0) {
+ dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
+ return;
+ }
}
/* Install the answer as answer to the transaction */
assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &usec) >= 0);
dns_server_packet_lost(t->server, IPPROTO_UDP, t->current_feature_level, usec - t->start_usec);
- dns_transaction_retry(t);
+ dns_transaction_retry(t, true);
return 0;
}
if (r < 0) {
return r;
if (t->current_feature_level < DNS_SERVER_FEATURE_LEVEL_UDP)
- return -EAGAIN;
+ return -EAGAIN; /* Sorry, can't do UDP, try TCP! */
if (!dns_server_dnssec_supported(t->server) && dns_type_is_dnssec(t->key->type))
return -EOPNOTSUPP;
log_debug("Timeout reached on transaction %" PRIu16 ".", t->id);
- dns_transaction_retry(t);
+ dns_transaction_retry(t, true);
return 0;
}
assert(t);
assert(t->scope);
+
switch (t->scope->protocol) {
case DNS_PROTOCOL_DNS:
+
+ /* When we do TCP, grant a much longer timeout, as in this case there's no need for us to quickly
+ * resend, as the kernel does that anyway for us, and we really don't want to interrupt it in that
+ * needlessly. */
+ if (t->stream)
+ return TRANSACTION_TCP_TIMEOUT_USEC;
+
assert(t->server);
return t->server->resend_timeout;
case DNS_PROTOCOL_MDNS:
assert(t->n_attempts > 0);
- return (1 << (t->n_attempts - 1)) * USEC_PER_SEC;
+ if (t->probing)
+ return MDNS_PROBING_INTERVAL_USEC;
+ else
+ return (1 << (t->n_attempts - 1)) * USEC_PER_SEC;
case DNS_PROTOCOL_LLMNR:
return t->scope->resend_timeout;
* for probing or verifying a zone item. */
if (set_isempty(t->notify_zone_items)) {
- r = dns_zone_lookup(&t->scope->zone, t->key, &t->answer, NULL, NULL);
+ r = dns_zone_lookup(&t->scope->zone, t->key, dns_scope_ifindex(t->scope), &t->answer, NULL, NULL);
if (r < 0)
return r;
if (r > 0) {
/* Let's then prune all outdated entries */
dns_cache_prune(&t->scope->cache);
- r = dns_cache_lookup(&t->scope->cache, t->key, &t->answer_rcode, &t->answer, &t->answer_authenticated);
+ r = dns_cache_lookup(&t->scope->cache, t->key, t->clamp_ttl, &t->answer_rcode, &t->answer, &t->answer_authenticated);
if (r < 0)
return r;
if (r > 0) {
if (r < 0)
return r;
- r = dns_packet_append_key(p, t->key, NULL);
+ r = dns_packet_append_key(p, t->key, 0, NULL);
if (r < 0)
return r;
if (qdcount >= UINT16_MAX)
break;
- r = dns_packet_append_key(p, other->key, NULL);
+ r = dns_packet_append_key(p, other->key, 0, NULL);
/*
* If we can't stuff more questions into the packet, just give up.
if (r < 0)
return r;
- (void) sd_event_source_set_description(t->timeout_event_source, "dns-transaction-timeout");
+ (void) sd_event_source_set_description(other->timeout_event_source, "dns-transaction-timeout");
other->state = DNS_TRANSACTION_PENDING;
other->next_attempt_after = ts;
if (r < 0)
return r;
- r = dns_packet_append_key(p, t->key, NULL);
+ r = dns_packet_append_key(p, t->key, 0, NULL);
if (r < 0)
return r;
assert(t);
+ /* Returns > 0 if the transaction is now pending, returns 0 if could be processed immediately and has finished
+ * now. */
+
assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &ts) >= 0);
r = dns_transaction_prepare(t, ts);
af_to_name_short(t->scope->family));
if (!t->initial_jitter_scheduled &&
- (t->scope->protocol == DNS_PROTOCOL_LLMNR ||
- t->scope->protocol == DNS_PROTOCOL_MDNS)) {
+ IN_SET(t->scope->protocol, DNS_PROTOCOL_LLMNR, DNS_PROTOCOL_MDNS)) {
usec_t jitter, accuracy;
/* RFC 4795 Section 2.7 suggests all queries should be
r = dns_transaction_emit_udp(t);
if (r == -EMSGSIZE)
log_debug("Sending query via TCP since it is too large.");
- if (r == -EAGAIN)
+ else if (r == -EAGAIN)
log_debug("Sending query via TCP since server doesn't support UDP.");
- if (r == -EMSGSIZE || r == -EAGAIN)
+ if (IN_SET(r, -EMSGSIZE, -EAGAIN))
r = dns_transaction_open_tcp(t);
}
if (!t->server)
return true;
- if (t->current_feature_level < DNS_SERVER_FEATURE_LEVEL_DO)
- return false;
+ /* Note that we do not check the feature level actually used for the transaction but instead the feature level
+ * the server is known to support currently, as the transaction feature level might be lower than what the
+ * server actually supports, since we might have downgraded this transaction's feature level because we got a
+ * SERVFAIL earlier and wanted to check whether downgrading fixes it. */
return dns_server_dnssec_supported(t->server);
}
r = dns_resource_key_match_rr(t->key, rr, NULL);
if (r < 0)
return r;
- if (r == 0)
- continue;
+ if (r == 0) {
+ /* Hmm, so this SOA RR doesn't match our original question. In this case, maybe this is
+ * a negative reply, and we need the a SOA RR's TTL in order to cache a negative entry?
+ * If so, we need to validate it, too. */
+
+ r = dns_answer_match_key(t->answer, t->key, NULL);
+ if (r < 0)
+ return r;
+ if (r > 0) /* positive reply, we won't need the SOA and hence don't need to validate
+ * it. */
+ continue;
+ }
r = dnssec_has_rrsig(t->answer, rr->key);
if (r < 0)
if (r > 0) {
/* The lookup is from a TLD that is proven not to
* exist, and we are in downgrade mode, hence ignore
- * that fact that we didn't get any NSEC RRs.*/
+ * that fact that we didn't get any NSEC RRs. */
log_info("Detected a negative query %s in a private DNS zone, permitting unsigned response.",
dns_resource_key_to_string(t->key, key_str, sizeof key_str));
const char *source;
/* This RRset validated, but as a wildcard. This means we need
- * to prove via NSEC/NSEC3 that no matching non-wildcard RR exists.*/
+ * to prove via NSEC/NSEC3 that no matching non-wildcard RR exists. */
/* First step, determine the source of synthesis */
r = dns_resource_record_source(rrsig, &source);
return r;
if (r == 0) {
/* Data does not require signing. In that case, just copy it over,
- * but remember that this is by no means authenticated.*/
+ * but remember that this is by no means authenticated. */
r = dns_answer_move_by_key(validated, &t->answer, rr->key, 0);
if (r < 0)
return r;
if (!dns_transaction_dnssec_supported_full(t)) {
/* The server does not support DNSSEC, or doesn't augment responses with RRSIGs. */
t->answer_dnssec_result = DNSSEC_INCOMPATIBLE_SERVER;
- log_debug("Not validating response for %" PRIu16 ", server lacks DNSSEC support.", t->id);
+ log_debug("Not validating response for %" PRIu16 ", used server feature level does not support DNSSEC.", t->id);
return 0;
}
projects / thirdparty / systemd.git / blobdiff