mirror of
https://github.com/systemd/systemd
synced 2024-07-21 10:17:21 +00:00
Merge pull request #23875 from yuwata/resolve-mdns-fix-use-after-free
resolve: mdns: fix use-after-free
This commit is contained in:
Luca Boccassi
GitHub
commit
bffb318491
|
|
@ -1242,16 +1242,14 @@ int dns_cache_check_conflicts(DnsCache *cache, DnsResourceRecord *rr, int owner_
|
|||
return 1;
|
||||
}
|
||||
|
||||
int dns_cache_export_shared_to_packet(DnsCache *cache, DnsPacket *p) {
|
||||
int dns_cache_export_shared_to_packet(DnsCache *cache, DnsPacket *p, usec_t ts, unsigned max_rr) {
|
||||
unsigned ancount = 0;
|
||||
DnsCacheItem *i;
|
||||
usec_t t;
|
||||
int r;
|
||||
|
||||
assert(cache);
|
||||
assert(p);
|
||||
|
||||
t = now(CLOCK_BOOTTIME);
|
||||
assert(p->protocol == DNS_PROTOCOL_MDNS);
|
||||
|
||||
HASHMAP_FOREACH(i, cache->by_key)
|
||||
LIST_FOREACH(by_key, j, i) {
|
||||
|
|
@ -1263,14 +1261,17 @@ int dns_cache_export_shared_to_packet(DnsCache *cache, DnsPacket *p) {
|
|||
|
||||
/* RFC6762 7.1: Don't append records with less than half the TTL remaining
|
||||
* as known answers. */
|
||||
if (usec_sub_unsigned(j->until, t) < j->rr->ttl * USEC_PER_SEC / 2)
|
||||
if (usec_sub_unsigned(j->until, ts) < j->rr->ttl * USEC_PER_SEC / 2)
|
||||
continue;
|
||||
|
||||
r = dns_packet_append_rr(p, j->rr, 0, NULL, NULL);
|
||||
if (r == -EMSGSIZE && p->protocol == DNS_PROTOCOL_MDNS) {
|
||||
/* For mDNS, if we're unable to stuff all known answers into the given packet,
|
||||
* allocate a new one, push the RR into that one and link it to the current one.
|
||||
*/
|
||||
if (r == -EMSGSIZE) {
|
||||
if (max_rr == 0)
|
||||
/* If max_rr == 0, do not allocate more packets. */
|
||||
goto finalize;
|
||||
|
||||
/* If we're unable to stuff all known answers into the given packet, allocate
|
||||
* a new one, push the RR into that one and link it to the current one. */
|
||||
|
||||
DNS_PACKET_HEADER(p)->ancount = htobe16(ancount);
|
||||
ancount = 0;
|
||||
|
|
@ -1288,8 +1289,21 @@ int dns_cache_export_shared_to_packet(DnsCache *cache, DnsPacket *p) {
|
|||
return r;
|
||||
|
||||
ancount++;
|
||||
if (max_rr > 0 && ancount >= max_rr) {
|
||||
DNS_PACKET_HEADER(p)->ancount = htobe16(ancount);
|
||||
ancount = 0;
|
||||
|
||||
r = dns_packet_new_query(&p->more, p->protocol, 0, true);
|
||||
if (r < 0)
|
||||
return r;
|
||||
|
||||
p = p->more;
|
||||
|
||||
max_rr = UINT_MAX;
|
||||
}
|
||||
}
|
||||
|
||||
finalize:
|
||||
DNS_PACKET_HEADER(p)->ancount = htobe16(ancount);
|
||||
|
||||
return 0;
|
||||
|
|
|
|||
|
|
@ -53,4 +53,4 @@ bool dns_cache_is_empty(DnsCache *cache);
|
|||
|
||||
unsigned dns_cache_size(DnsCache *cache);
|
||||
|
||||
int dns_cache_export_shared_to_packet(DnsCache *cache, DnsPacket *p);
|
||||
int dns_cache_export_shared_to_packet(DnsCache *cache, DnsPacket *p, usec_t ts, unsigned max_rr);
|
||||
|
|
|
|||
|
|
@ -1011,7 +1011,9 @@ void dns_scope_process_query(DnsScope *s, DnsStream *stream, DnsPacket *p) {
|
|||
return;
|
||||
}
|
||||
|
||||
assert(dns_question_size(p->question) == 1);
|
||||
if (dns_question_size(p->question) != 1)
|
||||
return (void) log_debug("Received LLMNR query without question or multiple questions, ignoring.");
|
||||
|
||||
key = dns_question_first_key(p->question);
|
||||
|
||||
r = dns_zone_lookup(&s->zone, key, 0, &answer, &soa, &tentative);
|
||||
|
|
@ -1204,7 +1206,6 @@ static int on_conflict_dispatch(sd_event_source *es, usec_t usec, void *userdata
|
|||
}
|
||||
|
||||
int dns_scope_notify_conflict(DnsScope *scope, DnsResourceRecord *rr) {
|
||||
usec_t jitter;
|
||||
int r;
|
||||
|
||||
assert(scope);
|
||||
|
|
@ -1233,15 +1234,12 @@ int dns_scope_notify_conflict(DnsScope *scope, DnsResourceRecord *rr) {
|
|||
if (scope->conflict_event_source)
|
||||
return 0;
|
||||
|
||||
random_bytes(&jitter, sizeof(jitter));
|
||||
jitter %= LLMNR_JITTER_INTERVAL_USEC;
|
||||
|
||||
r = sd_event_add_time_relative(
|
||||
scope->manager->event,
|
||||
&scope->conflict_event_source,
|
||||
CLOCK_BOOTTIME,
|
||||
jitter,
|
||||
LLMNR_JITTER_INTERVAL_USEC,
|
||||
random_u64_range(LLMNR_JITTER_INTERVAL_USEC),
|
||||
0,
|
||||
on_conflict_dispatch, scope);
|
||||
if (r < 0)
|
||||
return log_debug_errno(r, "Failed to add conflict dispatch event: %m");
|
||||
|
|
@ -1511,7 +1509,7 @@ int dns_scope_announce(DnsScope *scope, bool goodbye) {
|
|||
&scope->announce_event_source,
|
||||
CLOCK_BOOTTIME,
|
||||
MDNS_ANNOUNCE_DELAY,
|
||||
MDNS_JITTER_RANGE_USEC,
|
||||
0,
|
||||
on_announcement_timeout, scope);
|
||||
if (r < 0)
|
||||
return log_debug_errno(r, "Failed to schedule second announcement: %m");
|
||||
|
|
|
|||
|
|
@ -1551,6 +1551,33 @@ static int on_transaction_timeout(sd_event_source *s, usec_t usec, void *userdat
|
|||
return 0;
|
||||
}
|
||||
|
||||
static int dns_transaction_setup_timeout(
|
||||
DnsTransaction *t,
|
||||
usec_t timeout_usec /* relative */,
|
||||
usec_t next_usec /* CLOCK_BOOTTIME */) {
|
||||
|
||||
int r;
|
||||
|
||||
assert(t);
|
||||
|
||||
dns_transaction_stop_timeout(t);
|
||||
|
||||
r = sd_event_add_time_relative(
|
||||
t->scope->manager->event,
|
||||
&t->timeout_event_source,
|
||||
CLOCK_BOOTTIME,
|
||||
timeout_usec, 0,
|
||||
on_transaction_timeout, t);
|
||||
if (r < 0)
|
||||
return r;
|
||||
|
||||
(void) sd_event_source_set_description(t->timeout_event_source, "dns-transaction-timeout");
|
||||
|
||||
t->next_attempt_after = next_usec;
|
||||
t->state = DNS_TRANSACTION_PENDING;
|
||||
return 0;
|
||||
}
|
||||
|
||||
static usec_t transaction_get_resend_timeout(DnsTransaction *t) {
|
||||
assert(t);
|
||||
assert(t->scope);
|
||||
|
|
@ -1568,11 +1595,12 @@ static usec_t transaction_get_resend_timeout(DnsTransaction *t) {
|
|||
return DNS_TIMEOUT_USEC;
|
||||
|
||||
case DNS_PROTOCOL_MDNS:
|
||||
assert(t->n_attempts > 0);
|
||||
if (t->probing)
|
||||
return MDNS_PROBING_INTERVAL_USEC;
|
||||
else
|
||||
return (1 << (t->n_attempts - 1)) * USEC_PER_SEC;
|
||||
|
||||
/* See RFC 6762 Section 5.1 suggests that timeout should be a few seconds. */
|
||||
assert(t->n_attempts > 0);
|
||||
return (1 << (t->n_attempts - 1)) * USEC_PER_SEC;
|
||||
|
||||
case DNS_PROTOCOL_LLMNR:
|
||||
return t->scope->resend_timeout;
|
||||
|
|
@ -1622,7 +1650,7 @@ static int dns_transaction_prepare(DnsTransaction *t, usec_t ts) {
|
|||
return 0;
|
||||
}
|
||||
|
||||
if (t->n_attempts >= dns_transaction_attempts_max(t->scope->protocol, t->probing)) {
|
||||
if (t->n_attempts >= TRANSACTION_ATTEMPTS_MAX(t->scope->protocol)) {
|
||||
DnsTransactionState result;
|
||||
|
||||
if (t->scope->protocol == DNS_PROTOCOL_LLMNR)
|
||||
|
|
@ -1752,13 +1780,30 @@ static int dns_transaction_prepare(DnsTransaction *t, usec_t ts) {
|
|||
return 1;
|
||||
}
|
||||
|
||||
static int dns_packet_append_zone(DnsPacket *p, DnsTransaction *t, DnsResourceKey *k, unsigned *nscount) {
|
||||
_cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
|
||||
bool tentative;
|
||||
int r;
|
||||
|
||||
assert(p);
|
||||
assert(t);
|
||||
assert(k);
|
||||
|
||||
if (k->type != DNS_TYPE_ANY)
|
||||
return 0;
|
||||
|
||||
r = dns_zone_lookup(&t->scope->zone, k, t->scope->link->ifindex, &answer, NULL, &tentative);
|
||||
if (r < 0)
|
||||
return r;
|
||||
|
||||
return dns_packet_append_answer(p, answer, nscount);
|
||||
}
|
||||
|
||||
static int dns_transaction_make_packet_mdns(DnsTransaction *t) {
|
||||
_cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
|
||||
bool add_known_answers = false;
|
||||
DnsResourceKey *tkey;
|
||||
_cleanup_set_free_ Set *keys = NULL;
|
||||
unsigned qdcount;
|
||||
unsigned nscount = 0;
|
||||
unsigned qdcount, ancount = 0 /* avoid false maybe-uninitialized warning */, nscount;
|
||||
bool add_known_answers = false;
|
||||
usec_t ts;
|
||||
int r;
|
||||
|
||||
|
|
@ -1768,6 +1813,7 @@ static int dns_transaction_make_packet_mdns(DnsTransaction *t) {
|
|||
/* Discard any previously prepared packet, so we can start over and coalesce again */
|
||||
t->sent = dns_packet_unref(t->sent);
|
||||
|
||||
/* First, create a dummy packet to calculate packet size. */
|
||||
r = dns_packet_new_query(&p, t->scope->protocol, 0, false);
|
||||
if (r < 0)
|
||||
return r;
|
||||
|
|
@ -1781,11 +1827,14 @@ static int dns_transaction_make_packet_mdns(DnsTransaction *t) {
|
|||
if (dns_key_is_shared(dns_transaction_key(t)))
|
||||
add_known_answers = true;
|
||||
|
||||
if (dns_transaction_key(t)->type == DNS_TYPE_ANY) {
|
||||
r = set_ensure_put(&keys, &dns_resource_key_hash_ops, dns_transaction_key(t));
|
||||
if (r < 0)
|
||||
return r;
|
||||
}
|
||||
r = dns_packet_append_zone(p, t, dns_transaction_key(t), NULL);
|
||||
if (r < 0)
|
||||
return r;
|
||||
|
||||
/* Save appended keys */
|
||||
r = set_ensure_put(&keys, &dns_resource_key_hash_ops, dns_transaction_key(t));
|
||||
if (r < 0)
|
||||
return r;
|
||||
|
||||
/*
|
||||
* For mDNS, we want to coalesce as many open queries in pending transactions into one single
|
||||
|
|
@ -1795,90 +1844,114 @@ static int dns_transaction_make_packet_mdns(DnsTransaction *t) {
|
|||
|
||||
assert_se(sd_event_now(t->scope->manager->event, CLOCK_BOOTTIME, &ts) >= 0);
|
||||
|
||||
LIST_FOREACH(transactions_by_scope, other, t->scope->transactions) {
|
||||
for (bool restart = true; restart;) {
|
||||
restart = false;
|
||||
LIST_FOREACH(transactions_by_scope, other, t->scope->transactions) {
|
||||
size_t saved_packet_size;
|
||||
bool append = false;
|
||||
|
||||
/* Skip ourselves */
|
||||
if (other == t)
|
||||
continue;
|
||||
/* Skip ourselves */
|
||||
if (other == t)
|
||||
continue;
|
||||
|
||||
if (other->state != DNS_TRANSACTION_PENDING)
|
||||
continue;
|
||||
if (other->state != DNS_TRANSACTION_PENDING)
|
||||
continue;
|
||||
|
||||
if (other->next_attempt_after > ts)
|
||||
continue;
|
||||
if (other->next_attempt_after > ts)
|
||||
continue;
|
||||
|
||||
if (qdcount >= UINT16_MAX)
|
||||
break;
|
||||
if (!set_contains(keys, dns_transaction_key(other))) {
|
||||
r = dns_packet_append_key(p, dns_transaction_key(other), 0, &saved_packet_size);
|
||||
/* If we can't stuff more questions into the packet, just give up.
|
||||
* One of the 'other' transactions will fire later and take care of the rest. */
|
||||
if (r == -EMSGSIZE)
|
||||
break;
|
||||
if (r < 0)
|
||||
return r;
|
||||
|
||||
r = dns_packet_append_key(p, dns_transaction_key(other), 0, NULL);
|
||||
r = dns_packet_append_zone(p, t, dns_transaction_key(other), NULL);
|
||||
if (r == -EMSGSIZE)
|
||||
break;
|
||||
if (r < 0)
|
||||
return r;
|
||||
|
||||
/*
|
||||
* If we can't stuff more questions into the packet, just give up.
|
||||
* One of the 'other' transactions will fire later and take care of the rest.
|
||||
*/
|
||||
if (r == -EMSGSIZE)
|
||||
break;
|
||||
append = true;
|
||||
}
|
||||
|
||||
if (r < 0)
|
||||
return r;
|
||||
|
||||
r = dns_transaction_prepare(other, ts);
|
||||
if (r <= 0)
|
||||
continue;
|
||||
|
||||
ts += transaction_get_resend_timeout(other);
|
||||
|
||||
r = sd_event_add_time(
|
||||
other->scope->manager->event,
|
||||
&other->timeout_event_source,
|
||||
CLOCK_BOOTTIME,
|
||||
ts, 0,
|
||||
on_transaction_timeout, other);
|
||||
if (r < 0)
|
||||
return r;
|
||||
|
||||
(void) sd_event_source_set_description(other->timeout_event_source, "dns-transaction-timeout");
|
||||
|
||||
other->state = DNS_TRANSACTION_PENDING;
|
||||
other->next_attempt_after = ts;
|
||||
|
||||
qdcount++;
|
||||
|
||||
if (dns_key_is_shared(dns_transaction_key(other)))
|
||||
add_known_answers = true;
|
||||
|
||||
if (dns_transaction_key(other)->type == DNS_TYPE_ANY) {
|
||||
r = set_ensure_put(&keys, &dns_resource_key_hash_ops, dns_transaction_key(other));
|
||||
r = dns_transaction_prepare(other, ts);
|
||||
if (r < 0)
|
||||
return r;
|
||||
if (r == 0) {
|
||||
if (append)
|
||||
dns_packet_truncate(p, saved_packet_size);
|
||||
|
||||
/* In this case, not only this transaction, but multiple transactions may be
|
||||
* freed. Hence, we need to restart the loop. */
|
||||
restart = true;
|
||||
break;
|
||||
}
|
||||
|
||||
usec_t timeout = transaction_get_resend_timeout(other);
|
||||
r = dns_transaction_setup_timeout(other, timeout, usec_add(ts, timeout));
|
||||
if (r < 0)
|
||||
return r;
|
||||
|
||||
if (dns_key_is_shared(dns_transaction_key(other)))
|
||||
add_known_answers = true;
|
||||
|
||||
if (append) {
|
||||
r = set_ensure_put(&keys, &dns_resource_key_hash_ops, dns_transaction_key(other));
|
||||
if (r < 0)
|
||||
return r;
|
||||
}
|
||||
|
||||
qdcount++;
|
||||
if (qdcount >= UINT16_MAX)
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
DNS_PACKET_HEADER(p)->qdcount = htobe16(qdcount);
|
||||
|
||||
/* Append known answer section if we're asking for any shared record */
|
||||
if (add_known_answers) {
|
||||
r = dns_cache_export_shared_to_packet(&t->scope->cache, p);
|
||||
r = dns_cache_export_shared_to_packet(&t->scope->cache, p, ts, 0);
|
||||
if (r < 0)
|
||||
return r;
|
||||
|
||||
ancount = be16toh(DNS_PACKET_HEADER(p)->ancount);
|
||||
}
|
||||
|
||||
/* Then, create acctual packet. */
|
||||
p = dns_packet_unref(p);
|
||||
r = dns_packet_new_query(&p, t->scope->protocol, 0, false);
|
||||
if (r < 0)
|
||||
return r;
|
||||
|
||||
/* Questions */
|
||||
DnsResourceKey *k;
|
||||
SET_FOREACH(k, keys) {
|
||||
r = dns_packet_append_key(p, k, 0, NULL);
|
||||
if (r < 0)
|
||||
return r;
|
||||
}
|
||||
DNS_PACKET_HEADER(p)->qdcount = htobe16(qdcount);
|
||||
|
||||
/* Known answers */
|
||||
if (add_known_answers) {
|
||||
r = dns_cache_export_shared_to_packet(&t->scope->cache, p, ts, ancount);
|
||||
if (r < 0)
|
||||
return r;
|
||||
}
|
||||
|
||||
SET_FOREACH(tkey, keys) {
|
||||
_cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
|
||||
bool tentative;
|
||||
|
||||
r = dns_zone_lookup(&t->scope->zone, tkey, t->scope->link->ifindex, &answer, NULL, &tentative);
|
||||
if (r < 0)
|
||||
return r;
|
||||
|
||||
r = dns_packet_append_answer(p, answer, &nscount);
|
||||
/* Authorities */
|
||||
nscount = 0;
|
||||
SET_FOREACH(k, keys) {
|
||||
r = dns_packet_append_zone(p, t, k, &nscount);
|
||||
if (r < 0)
|
||||
return r;
|
||||
}
|
||||
DNS_PACKET_HEADER(p)->nscount = htobe16(nscount);
|
||||
|
||||
t->sent = TAKE_PTR(p);
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
|
|
@ -1950,45 +2023,36 @@ int dns_transaction_go(DnsTransaction *t) {
|
|||
|
||||
if (!t->initial_jitter_scheduled &&
|
||||
IN_SET(t->scope->protocol, DNS_PROTOCOL_LLMNR, DNS_PROTOCOL_MDNS)) {
|
||||
usec_t jitter, accuracy;
|
||||
usec_t jitter;
|
||||
|
||||
/* RFC 4795 Section 2.7 suggests all queries should be delayed by a random time from 0 to
|
||||
* JITTER_INTERVAL. */
|
||||
/* RFC 4795 Section 2.7 suggests all LLMNR queries should be delayed by a random time from 0 to
|
||||
* JITTER_INTERVAL.
|
||||
* RFC 6762 Section 8.1 suggests initial probe queries should be delayed by a random time from
|
||||
* 0 to 250ms. */
|
||||
|
||||
t->initial_jitter_scheduled = true;
|
||||
t->n_attempts = 0;
|
||||
|
||||
switch (t->scope->protocol) {
|
||||
|
||||
case DNS_PROTOCOL_LLMNR:
|
||||
jitter = random_u64_range(LLMNR_JITTER_INTERVAL_USEC);
|
||||
accuracy = LLMNR_JITTER_INTERVAL_USEC;
|
||||
break;
|
||||
|
||||
case DNS_PROTOCOL_MDNS:
|
||||
jitter = usec_add(random_u64_range(MDNS_JITTER_RANGE_USEC), MDNS_JITTER_MIN_USEC);
|
||||
accuracy = MDNS_JITTER_RANGE_USEC;
|
||||
if (t->probing)
|
||||
jitter = random_u64_range(MDNS_PROBING_INTERVAL_USEC);
|
||||
else
|
||||
jitter = 0;
|
||||
break;
|
||||
default:
|
||||
assert_not_reached();
|
||||
}
|
||||
|
||||
assert(!t->timeout_event_source);
|
||||
|
||||
r = sd_event_add_time_relative(
|
||||
t->scope->manager->event,
|
||||
&t->timeout_event_source,
|
||||
CLOCK_BOOTTIME,
|
||||
jitter, accuracy,
|
||||
on_transaction_timeout, t);
|
||||
r = dns_transaction_setup_timeout(t, jitter, ts);
|
||||
if (r < 0)
|
||||
return r;
|
||||
|
||||
(void) sd_event_source_set_description(t->timeout_event_source, "dns-transaction-timeout");
|
||||
|
||||
t->n_attempts = 0;
|
||||
t->next_attempt_after = ts;
|
||||
t->state = DNS_TRANSACTION_PENDING;
|
||||
|
||||
log_debug("Delaying %s transaction %" PRIu16 " for " USEC_FMT "us.",
|
||||
dns_protocol_to_string(t->scope->protocol),
|
||||
t->id,
|
||||
|
|
@ -2062,22 +2126,11 @@ int dns_transaction_go(DnsTransaction *t) {
|
|||
return dns_transaction_go(t);
|
||||
}
|
||||
|
||||
ts += transaction_get_resend_timeout(t);
|
||||
|
||||
r = sd_event_add_time(
|
||||
t->scope->manager->event,
|
||||
&t->timeout_event_source,
|
||||
CLOCK_BOOTTIME,
|
||||
ts, 0,
|
||||
on_transaction_timeout, t);
|
||||
usec_t timeout = transaction_get_resend_timeout(t);
|
||||
r = dns_transaction_setup_timeout(t, timeout, usec_add(ts, timeout));
|
||||
if (r < 0)
|
||||
return r;
|
||||
|
||||
(void) sd_event_source_set_description(t->timeout_event_source, "dns-transaction-timeout");
|
||||
|
||||
t->state = DNS_TRANSACTION_PENDING;
|
||||
t->next_attempt_after = ts;
|
||||
|
||||
return 1;
|
||||
}
|
||||
|
||||
|
|
|
|||
|
|
@ -201,10 +201,6 @@ DnsTransactionSource dns_transaction_source_from_string(const char *s) _pure_;
|
|||
/* LLMNR Jitter interval, see RFC 4795 Section 7 */
|
||||
#define LLMNR_JITTER_INTERVAL_USEC (100 * USEC_PER_MSEC)
|
||||
|
||||
/* mDNS Jitter interval, see RFC 6762 Section 5.2 */
|
||||
#define MDNS_JITTER_MIN_USEC (20 * USEC_PER_MSEC)
|
||||
#define MDNS_JITTER_RANGE_USEC (100 * USEC_PER_MSEC)
|
||||
|
||||
/* mDNS probing interval, see RFC 6762 Section 8.1 */
|
||||
#define MDNS_PROBING_INTERVAL_USEC (250 * USEC_PER_MSEC)
|
||||
|
||||
|
|
@ -214,31 +210,11 @@ DnsTransactionSource dns_transaction_source_from_string(const char *s) _pure_;
|
|||
/* Maximum attempts to send LLMNR requests, see RFC 4795 Section 2.7 */
|
||||
#define LLMNR_TRANSACTION_ATTEMPTS_MAX 3
|
||||
|
||||
/* Maximum attempts to send MDNS requests is one except for probe requests, see RFC 6762 Section 8.1
|
||||
* RFC 6762 differentiates between normal (single-shot/continuous) and probe requests.
|
||||
* It therefore makes sense to attempt each normal query only once with no retries.
|
||||
* Otherwise we'd be sending out three attempts for even a normal query. */
|
||||
#define MDNS_TRANSACTION_ATTEMPTS_MAX 1
|
||||
/* Maximum attempts to send MDNS requests, see RFC 6762 Section 8.1 */
|
||||
#define MDNS_TRANSACTION_ATTEMPTS_MAX 3
|
||||
|
||||
#define MDNS_PROBE_TRANSACTION_ATTEMPTS_MAX 3
|
||||
|
||||
static inline unsigned dns_transaction_attempts_max(DnsProtocol p, bool probing) {
|
||||
|
||||
switch (p) {
|
||||
|
||||
case DNS_PROTOCOL_LLMNR:
|
||||
return LLMNR_TRANSACTION_ATTEMPTS_MAX;
|
||||
|
||||
case DNS_PROTOCOL_MDNS:
|
||||
if (probing)
|
||||
return MDNS_PROBE_TRANSACTION_ATTEMPTS_MAX;
|
||||
else
|
||||
return MDNS_TRANSACTION_ATTEMPTS_MAX;
|
||||
|
||||
case DNS_PROTOCOL_DNS:
|
||||
return DNS_TRANSACTION_ATTEMPTS_MAX;
|
||||
|
||||
default:
|
||||
return 0;
|
||||
}
|
||||
}
|
||||
#define TRANSACTION_ATTEMPTS_MAX(p) (((p) == DNS_PROTOCOL_LLMNR) ? \
|
||||
LLMNR_TRANSACTION_ATTEMPTS_MAX : \
|
||||
(((p) == DNS_PROTOCOL_MDNS) ? \
|
||||
MDNS_TRANSACTION_ATTEMPTS_MAX : \
|
||||
DNS_TRANSACTION_ATTEMPTS_MAX))
|
||||
|
|
|
|||
|
|
@ -177,8 +177,6 @@ static int mdns_do_tiebreak(DnsResourceKey *key, DnsAnswer *answer, DnsPacket *p
|
|||
if (r < 0)
|
||||
return r;
|
||||
|
||||
assert(r > 0);
|
||||
|
||||
if (proposed_rrs_cmp(remote, r, our, size) > 0)
|
||||
return 1;
|
||||
|
||||
|
|
@ -207,10 +205,10 @@ static bool mdns_should_reply_using_unicast(DnsPacket *p) {
|
|||
}
|
||||
|
||||
/* All the questions in the query had a QU bit set, RFC 6762, section 5.4 */
|
||||
DNS_QUESTION_FOREACH_ITEM(item, p->question) {
|
||||
DNS_QUESTION_FOREACH_ITEM(item, p->question)
|
||||
if (!FLAGS_SET(item->flags, DNS_QUESTION_WANTS_UNICAST_REPLY))
|
||||
return false;
|
||||
}
|
||||
|
||||
return true;
|
||||
}
|
||||
|
||||
|
|
@ -256,7 +254,8 @@ static int mdns_scope_process_query(DnsScope *s, DnsPacket *p) {
|
|||
if (r < 0)
|
||||
return log_debug_errno(r, "Failed to extract resource records from incoming packet: %m");
|
||||
|
||||
assert_return((dns_question_size(p->question) > 0), -EINVAL);
|
||||
if (dns_question_size(p->question) <= 0)
|
||||
return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG), "Received mDNS query without question, ignoring.");
|
||||
|
||||
unicast_reply = mdns_should_reply_using_unicast(p);
|
||||
if (unicast_reply && !sender_on_local_subnet(s, p)) {
|
||||
|
|
@ -410,12 +409,28 @@ static int on_mdns_packet(sd_event_source *s, int fd, uint32_t revents, void *us
|
|||
}
|
||||
}
|
||||
|
||||
LIST_FOREACH(transactions_by_scope, t, scope->transactions) {
|
||||
r = dns_answer_match_key(p->answer, t->key, NULL);
|
||||
if (r < 0)
|
||||
log_debug_errno(r, "Failed to match resource key, ignoring: %m");
|
||||
else if (r > 0) /* This packet matches the transaction, let's pass it on as reply */
|
||||
for (bool match = true; match;) {
|
||||
match = false;
|
||||
LIST_FOREACH(transactions_by_scope, t, scope->transactions) {
|
||||
if (t->state != DNS_TRANSACTION_PENDING)
|
||||
continue;
|
||||
|
||||
r = dns_answer_match_key(p->answer, dns_transaction_key(t), NULL);
|
||||
if (r <= 0) {
|
||||
if (r < 0)
|
||||
log_debug_errno(r, "Failed to match resource key, ignoring: %m");
|
||||
continue;
|
||||
}
|
||||
|
||||
/* This packet matches the transaction, let's pass it on as reply */
|
||||
dns_transaction_process_reply(t, p, false);
|
||||
|
||||
/* The dns_transaction_process_reply() -> dns_transaction_complete() ->
|
||||
* dns_query_candidate_stop() may free multiple transactions. Hence, restart
|
||||
* the loop. */
|
||||
match = true;
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
dns_cache_put(&scope->cache, scope->manager->enable_cache, NULL, DNS_PACKET_RCODE(p), p->answer, NULL, false, _DNSSEC_RESULT_INVALID, UINT32_MAX, p->family, &p->sender);
|
||||
|
|
|
|||
Loading…
Reference in a new issue