+++ /dev/null
-/*-*- 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-dns-transaction.h"
-
-DnsTransaction* dns_transaction_free(DnsTransaction *t) {
- DnsQuery *q;
- DnsZoneItem *i;
-
- 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);
-
- if (t->scope) {
- LIST_REMOVE(transactions_by_scope, t->scope->transactions, t);
-
- if (t->id != 0)
- hashmap_remove(t->scope->manager->dns_transactions, UINT_TO_PTR(t->id));
- }
-
- 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, DnsQuestion *q) {
- _cleanup_(dns_transaction_freep) DnsTransaction *t = NULL;
- int r;
-
- assert(ret);
- assert(s);
- assert(q);
-
- r = hashmap_ensure_allocated(&s->manager->dns_transactions, NULL);
- if (r < 0)
- return r;
-
- t = new0(DnsTransaction, 1);
- if (!t)
- return -ENOMEM;
-
- t->question = dns_question_ref(q);
-
- 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;
- }
-
- LIST_PREPEND(transactions_by_scope, s->transactions, t);
- 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));
-
- if (!IN_SET(t->state, DNS_TRANSACTION_NULL, DNS_TRANSACTION_PENDING))
- 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_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) {
- _cleanup_close_ int fd = -1;
- int r;
-
- assert(t);
-
- if (t->stream)
- return 0;
-
- 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 = AF_UNSPEC;
-
- /* 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;
-
- fd = dns_scope_tcp_socket(t->scope, family, &address, 5355);
- }
- } else
- 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;
- }
-
- 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;
-}
-
-void dns_transaction_process_reply(DnsTransaction *t, DnsPacket *p) {
- int r;
-
- assert(t);
- assert(p);
- assert(t->state == 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. */
-
- 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 packets are not full responses but still
- * useful for identifying uniqueness conflicts during
- * probing. */
- if (DNS_PACKET_T(p)) {
- dns_transaction_tentative(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 (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;
- }
- }
-
- 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_scope_next_dns_server(t->scope);
-
- 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;
- }
-
- /* 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_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_scope_next_dns_server(t->scope);
-
- 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;
- unsigned n, added = 0;
- int r;
-
- assert(t);
-
- if (t->sent)
- return 0;
-
- r = dns_packet_new_query(&p, t->scope->protocol, 0);
- if (r < 0)
- return r;
-
- 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++;
- }
-
- if (added <= 0)
- return -EDOM;
-
- DNS_PACKET_HEADER(p)->qdcount = htobe16(added);
- DNS_PACKET_HEADER(p)->id = t->id;
-
- t->sent = p;
- p = NULL;
-
- return 0;
-}
-
-int dns_transaction_go(DnsTransaction *t) {
- bool had_stream;
- 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;
- }
-
- t->n_attempts++;
- 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->question, &t->cached_rcode, &t->cached);
- if (r < 0)
- return r;
- if (r > 0) {
- log_debug("Cache hit!");
- 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(),
- now(clock_boottime_or_monotonic()) + 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;
- }
-
- log_debug("Cache miss!");
-
- /* 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_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_transaction_open_tcp(t);
- } else {
- /* Try via UDP, and if that fails due to large size try via TCP */
- r = dns_scope_emit(t->scope, t->sent);
- 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;
- }
- 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_scope_next_dns_server(t->scope);
-
- return dns_transaction_go(t);
- }
-
- r = sd_event_add_time(
- t->scope->manager->event,
- &t->timeout_event_source,
- clock_boottime_or_monotonic(),
- now(clock_boottime_or_monotonic()) + TRANSACTION_TIMEOUT_USEC(t->scope->protocol), 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);
~ianmdlvl / elogind.git / blobdiff