4667e00a61
This hopefully makes this a bit more expressive and clarifies that the fd is not used for the DNS TCP socket. This also mimics how the LLMNR UDP fd is named in the manager object.
746 lines
24 KiB
C
746 lines
24 KiB
C
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
|
|
|
|
/***
|
|
This file is part of systemd.
|
|
|
|
Copyright 2014 Lennart Poettering
|
|
|
|
systemd is free software; you can redistribute it and/or modify it
|
|
under the terms of the GNU Lesser General Public License as published by
|
|
the Free Software Foundation; either version 2.1 of the License, or
|
|
(at your option) any later version.
|
|
|
|
systemd is distributed in the hope that it will be useful, but
|
|
WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public License
|
|
along with systemd; If not, see <http://www.gnu.org/licenses/>.
|
|
***/
|
|
|
|
#include "af-list.h"
|
|
|
|
#include "resolved-llmnr.h"
|
|
#include "resolved-dns-transaction.h"
|
|
#include "random-util.h"
|
|
#include "dns-domain.h"
|
|
|
|
DnsTransaction* dns_transaction_free(DnsTransaction *t) {
|
|
DnsQuery *q;
|
|
DnsZoneItem *i;
|
|
|
|
if (!t)
|
|
return NULL;
|
|
|
|
sd_event_source_unref(t->timeout_event_source);
|
|
|
|
dns_packet_unref(t->sent);
|
|
dns_packet_unref(t->received);
|
|
dns_answer_unref(t->cached);
|
|
|
|
sd_event_source_unref(t->dns_udp_event_source);
|
|
safe_close(t->dns_udp_fd);
|
|
|
|
dns_server_unref(t->server);
|
|
dns_stream_free(t->stream);
|
|
|
|
if (t->scope) {
|
|
hashmap_remove(t->scope->transactions, t->key);
|
|
|
|
if (t->id != 0)
|
|
hashmap_remove(t->scope->manager->dns_transactions, UINT_TO_PTR(t->id));
|
|
}
|
|
|
|
dns_resource_key_unref(t->key);
|
|
|
|
while ((q = set_steal_first(t->queries)))
|
|
set_remove(q->transactions, t);
|
|
set_free(t->queries);
|
|
|
|
while ((i = set_steal_first(t->zone_items)))
|
|
i->probe_transaction = NULL;
|
|
set_free(t->zone_items);
|
|
|
|
free(t);
|
|
return NULL;
|
|
}
|
|
|
|
DEFINE_TRIVIAL_CLEANUP_FUNC(DnsTransaction*, dns_transaction_free);
|
|
|
|
void dns_transaction_gc(DnsTransaction *t) {
|
|
assert(t);
|
|
|
|
if (t->block_gc > 0)
|
|
return;
|
|
|
|
if (set_isempty(t->queries) && set_isempty(t->zone_items))
|
|
dns_transaction_free(t);
|
|
}
|
|
|
|
int dns_transaction_new(DnsTransaction **ret, DnsScope *s, DnsResourceKey *key) {
|
|
_cleanup_(dns_transaction_freep) DnsTransaction *t = NULL;
|
|
int r;
|
|
|
|
assert(ret);
|
|
assert(s);
|
|
assert(key);
|
|
|
|
r = hashmap_ensure_allocated(&s->manager->dns_transactions, NULL);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
r = hashmap_ensure_allocated(&s->transactions, &dns_resource_key_hash_ops);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
t = new0(DnsTransaction, 1);
|
|
if (!t)
|
|
return -ENOMEM;
|
|
|
|
t->dns_udp_fd = -1;
|
|
t->key = dns_resource_key_ref(key);
|
|
|
|
/* Find a fresh, unused transaction id */
|
|
do
|
|
random_bytes(&t->id, sizeof(t->id));
|
|
while (t->id == 0 ||
|
|
hashmap_get(s->manager->dns_transactions, UINT_TO_PTR(t->id)));
|
|
|
|
r = hashmap_put(s->manager->dns_transactions, UINT_TO_PTR(t->id), t);
|
|
if (r < 0) {
|
|
t->id = 0;
|
|
return r;
|
|
}
|
|
|
|
r = hashmap_put(s->transactions, t->key, t);
|
|
if (r < 0) {
|
|
hashmap_remove(s->manager->dns_transactions, UINT_TO_PTR(t->id));
|
|
return r;
|
|
}
|
|
|
|
t->scope = s;
|
|
|
|
if (ret)
|
|
*ret = t;
|
|
|
|
t = NULL;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void dns_transaction_stop(DnsTransaction *t) {
|
|
assert(t);
|
|
|
|
t->timeout_event_source = sd_event_source_unref(t->timeout_event_source);
|
|
t->stream = dns_stream_free(t->stream);
|
|
}
|
|
|
|
static void dns_transaction_tentative(DnsTransaction *t, DnsPacket *p) {
|
|
_cleanup_free_ char *pretty = NULL;
|
|
DnsZoneItem *z;
|
|
|
|
assert(t);
|
|
assert(p);
|
|
|
|
if (manager_our_packet(t->scope->manager, p) != 0)
|
|
return;
|
|
|
|
in_addr_to_string(p->family, &p->sender, &pretty);
|
|
|
|
log_debug("Transaction on scope %s on %s/%s got tentative packet from %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),
|
|
pretty);
|
|
|
|
/* RFC 4795, Section 4.1 says that the peer with the
|
|
* lexicographically smaller IP address loses */
|
|
if (memcmp(&p->sender, &p->destination, FAMILY_ADDRESS_SIZE(p->family)) >= 0) {
|
|
log_debug("Peer has lexicographically larger IP address and thus lost in the conflict.");
|
|
return;
|
|
}
|
|
|
|
log_debug("We have the lexicographically larger IP address and thus lost in the conflict.");
|
|
|
|
t->block_gc++;
|
|
while ((z = set_first(t->zone_items))) {
|
|
/* First, make sure the zone item drops the reference
|
|
* to us */
|
|
dns_zone_item_probe_stop(z);
|
|
|
|
/* Secondly, report this as conflict, so that we might
|
|
* look for a different hostname */
|
|
dns_zone_item_conflict(z);
|
|
}
|
|
t->block_gc--;
|
|
|
|
dns_transaction_gc(t);
|
|
}
|
|
|
|
void dns_transaction_complete(DnsTransaction *t, DnsTransactionState state) {
|
|
DnsQuery *q;
|
|
DnsZoneItem *z;
|
|
Iterator i;
|
|
|
|
assert(t);
|
|
assert(!IN_SET(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. */
|
|
|
|
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_transaction_state_to_string(state));
|
|
|
|
t->state = state;
|
|
|
|
dns_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);
|
|
SET_FOREACH(z, t->zone_items, i)
|
|
dns_zone_item_ready(z);
|
|
t->block_gc--;
|
|
|
|
dns_transaction_gc(t);
|
|
}
|
|
|
|
static int on_stream_complete(DnsStream *s, int error) {
|
|
_cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
|
|
DnsTransaction *t;
|
|
|
|
assert(s);
|
|
assert(s->transaction);
|
|
|
|
/* Copy the data we care about out of the stream before we
|
|
* destroy it. */
|
|
t = s->transaction;
|
|
p = dns_packet_ref(s->read_packet);
|
|
|
|
t->stream = dns_stream_free(t->stream);
|
|
|
|
if (error != 0) {
|
|
dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES);
|
|
return 0;
|
|
}
|
|
|
|
if (dns_packet_validate_reply(p) <= 0) {
|
|
log_debug("Invalid LLMNR TCP packet.");
|
|
dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
|
|
return 0;
|
|
}
|
|
|
|
dns_scope_check_conflicts(t->scope, p);
|
|
|
|
t->block_gc++;
|
|
dns_transaction_process_reply(t, p);
|
|
t->block_gc--;
|
|
|
|
/* If the response wasn't useful, then complete the transition now */
|
|
if (t->state == DNS_TRANSACTION_PENDING)
|
|
dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int dns_transaction_open_tcp(DnsTransaction *t) {
|
|
DnsServer *server = NULL;
|
|
_cleanup_close_ int fd = -1;
|
|
int r;
|
|
|
|
assert(t);
|
|
|
|
if (t->stream)
|
|
return 0;
|
|
|
|
switch (t->scope->protocol) {
|
|
case DNS_PROTOCOL_DNS:
|
|
fd = dns_scope_tcp_socket(t->scope, AF_UNSPEC, NULL, 53, &server);
|
|
break;
|
|
|
|
case DNS_PROTOCOL_LLMNR:
|
|
/* When we already received a reply 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, NULL);
|
|
else {
|
|
union in_addr_union address;
|
|
int family = AF_UNSPEC;
|
|
|
|
/* Otherwise, try to talk to the owner of a
|
|
* the IP address, in case this is a reverse
|
|
* PTR lookup */
|
|
|
|
r = dns_name_address(DNS_RESOURCE_KEY_NAME(t->key), &family, &address);
|
|
if (r < 0)
|
|
return r;
|
|
if (r == 0)
|
|
return -EINVAL;
|
|
if (family != t->scope->family)
|
|
return -ESRCH;
|
|
|
|
fd = dns_scope_tcp_socket(t->scope, family, &address, LLMNR_PORT, NULL);
|
|
}
|
|
|
|
break;
|
|
|
|
default:
|
|
return -EAFNOSUPPORT;
|
|
}
|
|
|
|
if (fd < 0)
|
|
return fd;
|
|
|
|
r = dns_stream_new(t->scope->manager, &t->stream, t->scope->protocol, fd);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
fd = -1;
|
|
|
|
r = dns_stream_write_packet(t->stream, t->sent);
|
|
if (r < 0) {
|
|
t->stream = dns_stream_free(t->stream);
|
|
return r;
|
|
}
|
|
|
|
dns_server_unref(t->server);
|
|
t->server = dns_server_ref(server);
|
|
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 void dns_transaction_next_dns_server(DnsTransaction *t) {
|
|
assert(t);
|
|
|
|
t->server = dns_server_unref(t->server);
|
|
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_scope_next_dns_server(t->scope);
|
|
}
|
|
|
|
void dns_transaction_process_reply(DnsTransaction *t, DnsPacket *p) {
|
|
usec_t ts;
|
|
int r;
|
|
|
|
assert(t);
|
|
assert(p);
|
|
assert(t->state == DNS_TRANSACTION_PENDING);
|
|
assert(t->scope);
|
|
assert(t->scope->manager);
|
|
|
|
/* Note that this call might invalidate the query. Callers
|
|
* should hence not attempt to access the query or transaction
|
|
* after calling this function. */
|
|
|
|
switch (t->scope->protocol) {
|
|
case 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 packets are not full responses but still
|
|
* useful for identifying uniqueness conflicts during
|
|
* probing. */
|
|
if (DNS_PACKET_LLMNR_T(p)) {
|
|
dns_transaction_tentative(t, p);
|
|
return;
|
|
}
|
|
|
|
break;
|
|
|
|
case DNS_PROTOCOL_DNS:
|
|
break;
|
|
|
|
default:
|
|
assert_not_reached("Invalid DNS protocol.");
|
|
}
|
|
|
|
if (t->received != p) {
|
|
dns_packet_unref(t->received);
|
|
t->received = dns_packet_ref(p);
|
|
}
|
|
|
|
if (p->ipproto == IPPROTO_TCP) {
|
|
if (DNS_PACKET_TC(p)) {
|
|
/* Truncated via TCP? Somebody must be fucking with us */
|
|
dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
|
|
return;
|
|
}
|
|
|
|
if (DNS_PACKET_ID(p) != t->id) {
|
|
/* Not the reply to our query? Somebody must be fucking with us */
|
|
dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
|
|
return;
|
|
}
|
|
}
|
|
|
|
assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &ts) >= 0);
|
|
|
|
switch (t->scope->protocol) {
|
|
case DNS_PROTOCOL_DNS:
|
|
assert(t->server);
|
|
|
|
dns_server_packet_received(t->server, ts - t->start_usec);
|
|
|
|
break;
|
|
case DNS_PROTOCOL_LLMNR:
|
|
case DNS_PROTOCOL_MDNS:
|
|
dns_scope_packet_received(t->scope, ts - t->start_usec);
|
|
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
|
|
if (DNS_PACKET_TC(p)) {
|
|
/* Response was truncated, let's try again with good old TCP */
|
|
r = dns_transaction_open_tcp(t);
|
|
if (r == -ESRCH) {
|
|
/* No servers found? Damn! */
|
|
dns_transaction_complete(t, DNS_TRANSACTION_NO_SERVERS);
|
|
return;
|
|
}
|
|
if (r < 0) {
|
|
/* On LLMNR, if we cannot connect to the host,
|
|
* we immediately give up */
|
|
if (t->scope->protocol == DNS_PROTOCOL_LLMNR) {
|
|
dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES);
|
|
return;
|
|
}
|
|
|
|
/* On DNS, couldn't send? Try immediately again, with a new server */
|
|
dns_transaction_next_dns_server(t);
|
|
|
|
r = dns_transaction_go(t);
|
|
if (r < 0) {
|
|
dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES);
|
|
return;
|
|
}
|
|
|
|
return;
|
|
}
|
|
}
|
|
|
|
/* Parse and update the cache */
|
|
r = dns_packet_extract(p);
|
|
if (r < 0) {
|
|
dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
|
|
return;
|
|
}
|
|
|
|
/* Only consider responses with equivalent query section to the request */
|
|
if (p->question->n_keys != 1 || dns_resource_key_equal(p->question->keys[0], t->key) <= 0) {
|
|
dns_transaction_complete(t, DNS_TRANSACTION_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, p->family, &p->sender);
|
|
|
|
if (DNS_PACKET_RCODE(p) == DNS_RCODE_SUCCESS)
|
|
dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS);
|
|
else
|
|
dns_transaction_complete(t, DNS_TRANSACTION_FAILURE);
|
|
}
|
|
|
|
static int on_dns_packet(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
|
|
_cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
|
|
DnsTransaction *t = userdata;
|
|
int r;
|
|
|
|
assert(t);
|
|
assert(t->scope);
|
|
|
|
r = manager_recv(t->scope->manager, fd, DNS_PROTOCOL_DNS, &p);
|
|
if (r <= 0)
|
|
return r;
|
|
|
|
if (dns_packet_validate_reply(p) > 0 &&
|
|
DNS_PACKET_ID(p) == t->id)
|
|
dns_transaction_process_reply(t, p);
|
|
else
|
|
log_debug("Invalid DNS packet.");
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int dns_transaction_emit(DnsTransaction *t) {
|
|
int r;
|
|
|
|
assert(t);
|
|
|
|
if (t->scope->protocol == DNS_PROTOCOL_DNS && !t->server) {
|
|
DnsServer *server = NULL;
|
|
_cleanup_close_ int fd = -1;
|
|
|
|
fd = dns_scope_udp_dns_socket(t->scope, &server);
|
|
if (fd < 0)
|
|
return fd;
|
|
|
|
r = sd_event_add_io(t->scope->manager->event, &t->dns_udp_event_source, fd, EPOLLIN, on_dns_packet, t);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
t->dns_udp_fd = fd;
|
|
fd = -1;
|
|
t->server = dns_server_ref(server);
|
|
}
|
|
|
|
r = dns_scope_emit(t->scope, t->dns_udp_fd, t->sent);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int on_transaction_timeout(sd_event_source *s, usec_t usec, void *userdata) {
|
|
DnsTransaction *t = userdata;
|
|
int r;
|
|
|
|
assert(s);
|
|
assert(t);
|
|
|
|
/* Timeout reached? Try again, with a new server */
|
|
dns_transaction_next_dns_server(t);
|
|
|
|
/* ... and possibly increased timeout */
|
|
if (t->server)
|
|
dns_server_packet_lost(t->server, usec - t->start_usec);
|
|
else
|
|
dns_scope_packet_lost(t->scope, usec - t->start_usec);
|
|
|
|
r = dns_transaction_go(t);
|
|
if (r < 0)
|
|
dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int dns_transaction_make_packet(DnsTransaction *t) {
|
|
_cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
|
|
int r;
|
|
|
|
assert(t);
|
|
|
|
if (t->sent)
|
|
return 0;
|
|
|
|
r = dns_packet_new_query(&p, t->scope->protocol, 0);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
r = dns_scope_good_key(t->scope, t->key);
|
|
if (r < 0)
|
|
return r;
|
|
if (r == 0)
|
|
return -EDOM;
|
|
|
|
r = dns_packet_append_key(p, t->key, NULL);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
DNS_PACKET_HEADER(p)->qdcount = htobe16(1);
|
|
DNS_PACKET_HEADER(p)->id = t->id;
|
|
|
|
t->sent = p;
|
|
p = NULL;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static usec_t transaction_get_resend_timeout(DnsTransaction *t) {
|
|
assert(t);
|
|
assert(t->scope);
|
|
|
|
switch (t->scope->protocol) {
|
|
case DNS_PROTOCOL_DNS:
|
|
assert(t->server);
|
|
|
|
return t->server->resend_timeout;
|
|
case DNS_PROTOCOL_LLMNR:
|
|
case DNS_PROTOCOL_MDNS:
|
|
return t->scope->resend_timeout;
|
|
default:
|
|
assert_not_reached("Invalid DNS protocol.");
|
|
}
|
|
}
|
|
|
|
int dns_transaction_go(DnsTransaction *t) {
|
|
bool had_stream;
|
|
usec_t ts;
|
|
int r;
|
|
|
|
assert(t);
|
|
|
|
had_stream = !!t->stream;
|
|
|
|
dns_transaction_stop(t);
|
|
|
|
log_debug("Excercising 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->scope->protocol)) {
|
|
dns_transaction_complete(t, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED);
|
|
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_transaction_complete(t, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED);
|
|
return 0;
|
|
}
|
|
|
|
assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &ts) >= 0);
|
|
|
|
t->n_attempts++;
|
|
t->start_usec = ts;
|
|
t->received = dns_packet_unref(t->received);
|
|
t->cached = dns_answer_unref(t->cached);
|
|
t->cached_rcode = 0;
|
|
|
|
/* Check the cache, but only if this transaction is not used
|
|
* for probing or verifying a zone item. */
|
|
if (set_isempty(t->zone_items)) {
|
|
|
|
/* Before trying the cache, let's make sure we figured out a
|
|
* server to use. Should this cause a change of server this
|
|
* might flush the cache. */
|
|
dns_scope_get_dns_server(t->scope);
|
|
|
|
/* Let's then prune all outdated entries */
|
|
dns_cache_prune(&t->scope->cache);
|
|
|
|
r = dns_cache_lookup(&t->scope->cache, t->key, &t->cached_rcode, &t->cached);
|
|
if (r < 0)
|
|
return r;
|
|
if (r > 0) {
|
|
if (t->cached_rcode == DNS_RCODE_SUCCESS)
|
|
dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS);
|
|
else
|
|
dns_transaction_complete(t, DNS_TRANSACTION_FAILURE);
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
if (t->scope->protocol == DNS_PROTOCOL_LLMNR && !t->initial_jitter) {
|
|
usec_t jitter;
|
|
|
|
/* RFC 4795 Section 2.7 suggests all queries should be
|
|
* delayed by a random time from 0 to JITTER_INTERVAL. */
|
|
|
|
t->initial_jitter = true;
|
|
|
|
random_bytes(&jitter, sizeof(jitter));
|
|
jitter %= LLMNR_JITTER_INTERVAL_USEC;
|
|
|
|
r = sd_event_add_time(
|
|
t->scope->manager->event,
|
|
&t->timeout_event_source,
|
|
clock_boottime_or_monotonic(),
|
|
ts + jitter,
|
|
LLMNR_JITTER_INTERVAL_USEC,
|
|
on_transaction_timeout, t);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
t->n_attempts = 0;
|
|
t->state = DNS_TRANSACTION_PENDING;
|
|
|
|
log_debug("Delaying LLMNR transaction for " USEC_FMT "us.", jitter);
|
|
return 0;
|
|
}
|
|
|
|
/* Otherwise, we need to ask the network */
|
|
r = dns_transaction_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_transaction_complete(t, DNS_TRANSACTION_NO_SERVERS);
|
|
return 0;
|
|
}
|
|
if (r < 0)
|
|
return r;
|
|
|
|
if (t->scope->protocol == DNS_PROTOCOL_LLMNR &&
|
|
(dns_name_endswith(DNS_RESOURCE_KEY_NAME(t->key), "in-addr.arpa") > 0 ||
|
|
dns_name_endswith(DNS_RESOURCE_KEY_NAME(t->key), "ip6.arpa") > 0)) {
|
|
|
|
/* RFC 4795, Section 2.4. says reverse lookups shall
|
|
* always be made via TCP on LLMNR */
|
|
r = dns_transaction_open_tcp(t);
|
|
} else {
|
|
/* Try via UDP, and if that fails due to large size try via TCP */
|
|
r = dns_transaction_emit(t);
|
|
if (r == -EMSGSIZE)
|
|
r = dns_transaction_open_tcp(t);
|
|
}
|
|
if (r == -ESRCH) {
|
|
/* No servers to send this to? */
|
|
dns_transaction_complete(t, DNS_TRANSACTION_NO_SERVERS);
|
|
return 0;
|
|
} else if (r < 0) {
|
|
if (t->scope->protocol != DNS_PROTOCOL_DNS) {
|
|
dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES);
|
|
return 0;
|
|
}
|
|
|
|
/* Couldn't send? Try immediately again, with a new server */
|
|
dns_transaction_next_dns_server(t);
|
|
|
|
return dns_transaction_go(t);
|
|
}
|
|
|
|
r = sd_event_add_time(
|
|
t->scope->manager->event,
|
|
&t->timeout_event_source,
|
|
clock_boottime_or_monotonic(),
|
|
ts + transaction_get_resend_timeout(t), 0,
|
|
on_transaction_timeout, t);
|
|
if (r < 0)
|
|
return r;
|
|
|
|
t->state = DNS_TRANSACTION_PENDING;
|
|
return 1;
|
|
}
|
|
|
|
static const char* const dns_transaction_state_table[_DNS_TRANSACTION_STATE_MAX] = {
|
|
[DNS_TRANSACTION_NULL] = "null",
|
|
[DNS_TRANSACTION_PENDING] = "pending",
|
|
[DNS_TRANSACTION_FAILURE] = "failure",
|
|
[DNS_TRANSACTION_SUCCESS] = "success",
|
|
[DNS_TRANSACTION_NO_SERVERS] = "no-servers",
|
|
[DNS_TRANSACTION_TIMEOUT] = "timeout",
|
|
[DNS_TRANSACTION_ATTEMPTS_MAX_REACHED] = "attempts-max-reached",
|
|
[DNS_TRANSACTION_INVALID_REPLY] = "invalid-reply",
|
|
[DNS_TRANSACTION_RESOURCES] = "resources",
|
|
[DNS_TRANSACTION_ABORTED] = "aborted",
|
|
};
|
|
DEFINE_STRING_TABLE_LOOKUP(dns_transaction_state, DnsTransactionState);
|