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Systemd/src/resolve/resolved-dns-query.c

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/*-*- 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 "alloc-util.h"
#include "dns-domain.h"
#include "hostname-util.h"
#include "local-addresses.h"
#include "resolved-dns-query.h"
#include "string-util.h"
/* How long to wait for the query in total */
#define QUERY_TIMEOUT_USEC (30 * USEC_PER_SEC)
#define CNAME_MAX 8
#define QUERIES_MAX 2048
#define AUXILIARY_QUERIES_MAX 64
static int dns_query_candidate_new(DnsQueryCandidate **ret, DnsQuery *q, DnsScope *s) {
DnsQueryCandidate *c;
assert(ret);
assert(q);
assert(s);
c = new0(DnsQueryCandidate, 1);
if (!c)
return -ENOMEM;
c->query = q;
c->scope = s;
LIST_PREPEND(candidates_by_query, q->candidates, c);
LIST_PREPEND(candidates_by_scope, s->query_candidates, c);
*ret = c;
return 0;
}
static void dns_query_candidate_stop(DnsQueryCandidate *c) {
DnsTransaction *t;
assert(c);
while ((t = set_steal_first(c->transactions))) {
set_remove(t->notify_query_candidates, c);
dns_transaction_gc(t);
}
}
DnsQueryCandidate* dns_query_candidate_free(DnsQueryCandidate *c) {
if (!c)
return NULL;
dns_query_candidate_stop(c);
set_free(c->transactions);
dns_search_domain_unref(c->search_domain);
if (c->query)
LIST_REMOVE(candidates_by_query, c->query->candidates, c);
if (c->scope)
LIST_REMOVE(candidates_by_scope, c->scope->query_candidates, c);
free(c);
return NULL;
}
static int dns_query_candidate_next_search_domain(DnsQueryCandidate *c) {
DnsSearchDomain *next = NULL;
assert(c);
if (c->search_domain && c->search_domain->linked) {
next = c->search_domain->domains_next;
if (!next) /* We hit the end of the list */
return 0;
} else {
next = dns_scope_get_search_domains(c->scope);
if (!next) /* OK, there's nothing. */
return 0;
}
dns_search_domain_unref(c->search_domain);
c->search_domain = dns_search_domain_ref(next);
return 1;
}
static int dns_query_candidate_add_transaction(DnsQueryCandidate *c, DnsResourceKey *key) {
DnsTransaction *t;
int r;
assert(c);
assert(key);
t = dns_scope_find_transaction(c->scope, key, true);
if (!t) {
r = dns_transaction_new(&t, c->scope, key);
if (r < 0)
return r;
} else {
if (set_contains(c->transactions, t))
return 0;
}
r = set_ensure_allocated(&c->transactions, NULL);
if (r < 0)
goto gc;
r = set_ensure_allocated(&t->notify_query_candidates, NULL);
if (r < 0)
goto gc;
r = set_put(t->notify_query_candidates, c);
if (r < 0)
goto gc;
r = set_put(c->transactions, t);
if (r < 0) {
(void) set_remove(t->notify_query_candidates, c);
goto gc;
}
return 1;
gc:
dns_transaction_gc(t);
return r;
}
static int dns_query_candidate_go(DnsQueryCandidate *c) {
DnsTransaction *t;
Iterator i;
int r;
assert(c);
/* Start the transactions that are not started yet */
SET_FOREACH(t, c->transactions, i) {
if (t->state != DNS_TRANSACTION_NULL)
continue;
r = dns_transaction_go(t);
if (r < 0)
return r;
}
return 0;
}
static DnsTransactionState dns_query_candidate_state(DnsQueryCandidate *c) {
DnsTransactionState state = DNS_TRANSACTION_NO_SERVERS;
DnsTransaction *t;
Iterator i;
assert(c);
if (c->error_code != 0)
return DNS_TRANSACTION_RESOURCES;
SET_FOREACH(t, c->transactions, i) {
switch (t->state) {
case DNS_TRANSACTION_NULL:
/* If there's a NULL transaction pending, then
* this means not all transactions where
* started yet, and we were called from within
* the stackframe that is supposed to start
* remaining transactions. In this case,
* simply claim the candidate is pending. */
case DNS_TRANSACTION_PENDING:
case DNS_TRANSACTION_VALIDATING:
/* If there's one transaction currently in
* VALIDATING state, then this means there's
* also one in PENDING state, hence we can
* return PENDING immediately. */
return DNS_TRANSACTION_PENDING;
case DNS_TRANSACTION_SUCCESS:
state = t->state;
break;
default:
if (state != DNS_TRANSACTION_SUCCESS)
state = t->state;
break;
}
}
return state;
}
static int dns_query_candidate_setup_transactions(DnsQueryCandidate *c) {
DnsQuestion *question;
DnsResourceKey *key;
int n = 0, r;
assert(c);
dns_query_candidate_stop(c);
question = dns_query_question_for_protocol(c->query, c->scope->protocol);
/* Create one transaction per question key */
DNS_QUESTION_FOREACH(key, question) {
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *new_key = NULL;
if (c->search_domain) {
r = dns_resource_key_new_append_suffix(&new_key, key, c->search_domain->name);
if (r < 0)
goto fail;
}
r = dns_query_candidate_add_transaction(c, new_key ?: key);
if (r < 0)
goto fail;
n++;
}
return n;
fail:
dns_query_candidate_stop(c);
return r;
}
void dns_query_candidate_notify(DnsQueryCandidate *c) {
DnsTransactionState state;
int r;
assert(c);
state = dns_query_candidate_state(c);
if (DNS_TRANSACTION_IS_LIVE(state))
return;
if (state != DNS_TRANSACTION_SUCCESS && c->search_domain) {
r = dns_query_candidate_next_search_domain(c);
if (r < 0)
goto fail;
if (r > 0) {
/* OK, there's another search domain to try, let's do so. */
r = dns_query_candidate_setup_transactions(c);
if (r < 0)
goto fail;
if (r > 0) {
/* New transactions where queued. Start them and wait */
r = dns_query_candidate_go(c);
if (r < 0)
goto fail;
return;
}
}
}
dns_query_ready(c->query);
return;
fail:
log_warning_errno(r, "Failed to follow search domains: %m");
c->error_code = r;
dns_query_ready(c->query);
}
static void dns_query_stop(DnsQuery *q) {
DnsQueryCandidate *c;
assert(q);
q->timeout_event_source = sd_event_source_unref(q->timeout_event_source);
LIST_FOREACH(candidates_by_query, c, q->candidates)
dns_query_candidate_stop(c);
}
static void dns_query_free_candidates(DnsQuery *q) {
assert(q);
while (q->candidates)
dns_query_candidate_free(q->candidates);
}
static void dns_query_reset_answer(DnsQuery *q) {
assert(q);
q->answer = dns_answer_unref(q->answer);
q->answer_rcode = 0;
q->answer_dnssec_result = _DNSSEC_RESULT_INVALID;
q->answer_authenticated = false;
q->answer_protocol = _DNS_PROTOCOL_INVALID;
q->answer_family = AF_UNSPEC;
q->answer_search_domain = dns_search_domain_unref(q->answer_search_domain);
}
DnsQuery *dns_query_free(DnsQuery *q) {
if (!q)
return NULL;
while (q->auxiliary_queries)
dns_query_free(q->auxiliary_queries);
if (q->auxiliary_for) {
assert(q->auxiliary_for->n_auxiliary_queries > 0);
q->auxiliary_for->n_auxiliary_queries--;
LIST_REMOVE(auxiliary_queries, q->auxiliary_for->auxiliary_queries, q);
}
dns_query_free_candidates(q);
dns_question_unref(q->question_idna);
dns_question_unref(q->question_utf8);
dns_query_reset_answer(q);
sd_bus_message_unref(q->request);
sd_bus_track_unref(q->bus_track);
free(q->request_address_string);
if (q->manager) {
LIST_REMOVE(queries, q->manager->dns_queries, q);
q->manager->n_dns_queries--;
}
free(q);
return NULL;
}
int dns_query_new(
Manager *m,
DnsQuery **ret,
DnsQuestion *question_utf8,
DnsQuestion *question_idna,
int ifindex, uint64_t flags) {
_cleanup_(dns_query_freep) DnsQuery *q = NULL;
DnsResourceKey *key;
bool good = false;
int r;
assert(m);
if (dns_question_size(question_utf8) > 0) {
r = dns_question_is_valid_for_query(question_utf8);
if (r < 0)
return r;
if (r == 0)
return -EINVAL;
good = true;
}
/* If the IDNA and UTF8 questions are the same, merge their references */
r = dns_question_is_equal(question_idna, question_utf8);
if (r < 0)
return r;
if (r > 0)
question_idna = question_utf8;
else {
if (dns_question_size(question_idna) > 0) {
r = dns_question_is_valid_for_query(question_idna);
if (r < 0)
return r;
if (r == 0)
return -EINVAL;
good = true;
}
}
if (!good) /* don't allow empty queries */
return -EINVAL;
if (m->n_dns_queries >= QUERIES_MAX)
return -EBUSY;
q = new0(DnsQuery, 1);
if (!q)
return -ENOMEM;
q->question_utf8 = dns_question_ref(question_utf8);
q->question_idna = dns_question_ref(question_idna);
q->ifindex = ifindex;
q->flags = flags;
q->answer_dnssec_result = _DNSSEC_RESULT_INVALID;
q->answer_protocol = _DNS_PROTOCOL_INVALID;
q->answer_family = AF_UNSPEC;
/* First dump UTF8 question */
DNS_QUESTION_FOREACH(key, question_utf8) {
_cleanup_free_ char *p = NULL;
r = dns_resource_key_to_string(key, &p);
if (r < 0)
return r;
log_debug("Looking up RR for %s.", strstrip(p));
}
/* And then dump the IDNA question, but only what hasn't been dumped already through the UTF8 question. */
DNS_QUESTION_FOREACH(key, question_idna) {
_cleanup_free_ char *p = NULL;
r = dns_question_contains(question_utf8, key);
if (r < 0)
return r;
if (r > 0)
continue;
r = dns_resource_key_to_string(key, &p);
if (r < 0)
return r;
log_debug("Looking up IDNA RR for %s.", strstrip(p));
}
LIST_PREPEND(queries, m->dns_queries, q);
m->n_dns_queries++;
q->manager = m;
if (ret)
*ret = q;
q = NULL;
return 0;
}
int dns_query_make_auxiliary(DnsQuery *q, DnsQuery *auxiliary_for) {
assert(q);
assert(auxiliary_for);
/* Ensure that that the query is not auxiliary yet, and
* nothing else is auxiliary to it either */
assert(!q->auxiliary_for);
assert(!q->auxiliary_queries);
/* Ensure that the unit we shall be made auxiliary for isn't
* auxiliary itself */
assert(!auxiliary_for->auxiliary_for);
if (auxiliary_for->n_auxiliary_queries >= AUXILIARY_QUERIES_MAX)
return -EAGAIN;
LIST_PREPEND(auxiliary_queries, auxiliary_for->auxiliary_queries, q);
q->auxiliary_for = auxiliary_for;
auxiliary_for->n_auxiliary_queries++;
return 0;
}
static void dns_query_complete(DnsQuery *q, DnsTransactionState state) {
assert(q);
assert(!DNS_TRANSACTION_IS_LIVE(state));
assert(DNS_TRANSACTION_IS_LIVE(q->state));
/* Note that this call might invalidate the query. Callers
* should hence not attempt to access the query or transaction
* after calling this function. */
q->state = state;
dns_query_stop(q);
if (q->complete)
q->complete(q);
}
static int on_query_timeout(sd_event_source *s, usec_t usec, void *userdata) {
DnsQuery *q = userdata;
assert(s);
assert(q);
dns_query_complete(q, DNS_TRANSACTION_TIMEOUT);
return 0;
}
static int dns_query_add_candidate(DnsQuery *q, DnsScope *s) {
DnsQueryCandidate *c;
int r;
assert(q);
assert(s);
r = dns_query_candidate_new(&c, q, s);
if (r < 0)
return r;
/* If this a single-label domain on DNS, we might append a suitable search domain first. */
if ((q->flags & SD_RESOLVED_NO_SEARCH) == 0) {
r = dns_scope_name_needs_search_domain(s, dns_question_first_name(q->question_idna));
if (r < 0)
goto fail;
if (r > 0) {
/* OK, we need a search domain now. Let's find one for this scope */
r = dns_query_candidate_next_search_domain(c);
if (r <= 0) /* if there's no search domain, then we won't add any transaction. */
goto fail;
}
}
r = dns_query_candidate_setup_transactions(c);
if (r < 0)
goto fail;
return 0;
fail:
dns_query_candidate_free(c);
return r;
}
static int SYNTHESIZE_IFINDEX(int ifindex) {
/* When the caller asked for resolving on a specific
* interface, we synthesize the answer for that
* interface. However, if nothing specific was claimed and we
* only return localhost RRs, we synthesize the answer for
* localhost. */
if (ifindex > 0)
return ifindex;
return LOOPBACK_IFINDEX;
}
static int SYNTHESIZE_FAMILY(uint64_t flags) {
/* Picks an address family depending on set flags. This is
* purely for synthesized answers, where the family we return
* for the reply should match what was requested in the
* question, even though we are synthesizing the answer
* here. */
if (!(flags & SD_RESOLVED_DNS)) {
if (flags & SD_RESOLVED_LLMNR_IPV4)
return AF_INET;
if (flags & SD_RESOLVED_LLMNR_IPV6)
return AF_INET6;
}
return AF_UNSPEC;
}
static DnsProtocol SYNTHESIZE_PROTOCOL(uint64_t flags) {
/* Similar as SYNTHESIZE_FAMILY() but does this for the
* protocol. If resolving via DNS was requested, we claim it
* was DNS. Similar, if nothing specific was
* requested. However, if only resolving via LLMNR was
* requested we return that. */
if (flags & SD_RESOLVED_DNS)
return DNS_PROTOCOL_DNS;
if (flags & SD_RESOLVED_LLMNR)
return DNS_PROTOCOL_LLMNR;
return DNS_PROTOCOL_DNS;
}
static int dns_type_to_af(uint16_t t) {
switch (t) {
case DNS_TYPE_A:
return AF_INET;
case DNS_TYPE_AAAA:
return AF_INET6;
case DNS_TYPE_ANY:
return AF_UNSPEC;
default:
return -EINVAL;
}
}
static int synthesize_localhost_rr(DnsQuery *q, const DnsResourceKey *key, DnsAnswer **answer) {
int r;
assert(q);
assert(key);
assert(answer);
r = dns_answer_reserve(answer, 2);
if (r < 0)
return r;
if (IN_SET(key->type, DNS_TYPE_A, DNS_TYPE_ANY)) {
_cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_A, DNS_RESOURCE_KEY_NAME(key));
if (!rr)
return -ENOMEM;
rr->a.in_addr.s_addr = htobe32(INADDR_LOOPBACK);
r = dns_answer_add(*answer, rr, SYNTHESIZE_IFINDEX(q->ifindex), DNS_ANSWER_AUTHENTICATED);
if (r < 0)
return r;
}
if (IN_SET(key->type, DNS_TYPE_AAAA, DNS_TYPE_ANY)) {
_cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_AAAA, DNS_RESOURCE_KEY_NAME(key));
if (!rr)
return -ENOMEM;
rr->aaaa.in6_addr = in6addr_loopback;
r = dns_answer_add(*answer, rr, SYNTHESIZE_IFINDEX(q->ifindex), DNS_ANSWER_AUTHENTICATED);
if (r < 0)
return r;
}
return 0;
}
static int answer_add_ptr(DnsAnswer **answer, const char *from, const char *to, int ifindex, DnsAnswerFlags flags) {
_cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_PTR, from);
if (!rr)
return -ENOMEM;
rr->ptr.name = strdup(to);
if (!rr->ptr.name)
return -ENOMEM;
return dns_answer_add(*answer, rr, ifindex, flags);
}
static int synthesize_localhost_ptr(DnsQuery *q, const DnsResourceKey *key, DnsAnswer **answer) {
int r;
assert(q);
assert(key);
assert(answer);
if (IN_SET(key->type, DNS_TYPE_PTR, DNS_TYPE_ANY)) {
r = dns_answer_reserve(answer, 1);
if (r < 0)
return r;
r = answer_add_ptr(answer, DNS_RESOURCE_KEY_NAME(key), "localhost", SYNTHESIZE_IFINDEX(q->ifindex), DNS_ANSWER_AUTHENTICATED);
if (r < 0)
return r;
}
return 0;
}
static int answer_add_addresses_rr(
DnsAnswer **answer,
const char *name,
struct local_address *addresses,
unsigned n_addresses) {
unsigned j;
int r;
assert(answer);
assert(name);
r = dns_answer_reserve(answer, n_addresses);
if (r < 0)
return r;
for (j = 0; j < n_addresses; j++) {
_cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
r = dns_resource_record_new_address(&rr, addresses[j].family, &addresses[j].address, name);
if (r < 0)
return r;
r = dns_answer_add(*answer, rr, addresses[j].ifindex, DNS_ANSWER_AUTHENTICATED);
if (r < 0)
return r;
}
return 0;
}
static int answer_add_addresses_ptr(
DnsAnswer **answer,
const char *name,
struct local_address *addresses,
unsigned n_addresses,
int af, const union in_addr_union *match) {
unsigned j;
int r;
assert(answer);
assert(name);
for (j = 0; j < n_addresses; j++) {
_cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
if (af != AF_UNSPEC) {
if (addresses[j].family != af)
continue;
if (match && !in_addr_equal(af, match, &addresses[j].address))
continue;
}
r = dns_answer_reserve(answer, 1);
if (r < 0)
return r;
r = dns_resource_record_new_reverse(&rr, addresses[j].family, &addresses[j].address, name);
if (r < 0)
return r;
r = dns_answer_add(*answer, rr, addresses[j].ifindex, DNS_ANSWER_AUTHENTICATED);
if (r < 0)
return r;
}
return 0;
}
static int synthesize_system_hostname_rr(DnsQuery *q, const DnsResourceKey *key, DnsAnswer **answer) {
_cleanup_free_ struct local_address *addresses = NULL;
int n = 0, af;
assert(q);
assert(key);
assert(answer);
af = dns_type_to_af(key->type);
if (af >= 0) {
n = local_addresses(q->manager->rtnl, q->ifindex, af, &addresses);
if (n < 0)
return n;
if (n == 0) {
struct local_address buffer[2];
/* If we have no local addresses then use ::1
* and 127.0.0.2 as local ones. */
if (af == AF_INET || af == AF_UNSPEC)
buffer[n++] = (struct local_address) {
.family = AF_INET,
.ifindex = SYNTHESIZE_IFINDEX(q->ifindex),
.address.in.s_addr = htobe32(0x7F000002),
};
if (af == AF_INET6 || af == AF_UNSPEC)
buffer[n++] = (struct local_address) {
.family = AF_INET6,
.ifindex = SYNTHESIZE_IFINDEX(q->ifindex),
.address.in6 = in6addr_loopback,
};
return answer_add_addresses_rr(answer, DNS_RESOURCE_KEY_NAME(key), buffer, n);
}
}
return answer_add_addresses_rr(answer, DNS_RESOURCE_KEY_NAME(key), addresses, n);
}
static int synthesize_system_hostname_ptr(DnsQuery *q, int af, const union in_addr_union *address, DnsAnswer **answer) {
_cleanup_free_ struct local_address *addresses = NULL;
int n, r;
assert(q);
assert(address);
assert(answer);
if (af == AF_INET && address->in.s_addr == htobe32(0x7F000002)) {
/* Always map the IPv4 address 127.0.0.2 to the local
* hostname, in addition to "localhost": */
r = dns_answer_reserve(answer, 3);
if (r < 0)
return r;
r = answer_add_ptr(answer, "2.0.0.127.in-addr.arpa", q->manager->llmnr_hostname, SYNTHESIZE_IFINDEX(q->ifindex), DNS_ANSWER_AUTHENTICATED);
if (r < 0)
return r;
r = answer_add_ptr(answer, "2.0.0.127.in-addr.arpa", q->manager->mdns_hostname, SYNTHESIZE_IFINDEX(q->ifindex), DNS_ANSWER_AUTHENTICATED);
if (r < 0)
return r;
r = answer_add_ptr(answer, "2.0.0.127.in-addr.arpa", "localhost", SYNTHESIZE_IFINDEX(q->ifindex), DNS_ANSWER_AUTHENTICATED);
if (r < 0)
return r;
return 0;
}
n = local_addresses(q->manager->rtnl, q->ifindex, af, &addresses);
if (n < 0)
return n;
r = answer_add_addresses_ptr(answer, q->manager->llmnr_hostname, addresses, n, af, address);
if (r < 0)
return r;
return answer_add_addresses_ptr(answer, q->manager->mdns_hostname, addresses, n, af, address);
}
static int synthesize_gateway_rr(DnsQuery *q, const DnsResourceKey *key, DnsAnswer **answer) {
_cleanup_free_ struct local_address *addresses = NULL;
int n = 0, af;
assert(q);
assert(key);
assert(answer);
af = dns_type_to_af(key->type);
if (af >= 0) {
n = local_gateways(q->manager->rtnl, q->ifindex, af, &addresses);
if (n < 0)
return n;
}
return answer_add_addresses_rr(answer, DNS_RESOURCE_KEY_NAME(key), addresses, n);
}
static int synthesize_gateway_ptr(DnsQuery *q, int af, const union in_addr_union *address, DnsAnswer **answer) {
_cleanup_free_ struct local_address *addresses = NULL;
int n;
assert(q);
assert(address);
assert(answer);
n = local_gateways(q->manager->rtnl, q->ifindex, af, &addresses);
if (n < 0)
return n;
return answer_add_addresses_ptr(answer, "gateway", addresses, n, af, address);
}
static int dns_query_synthesize_reply(DnsQuery *q, DnsTransactionState *state) {
_cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
DnsResourceKey *key;
int r;
assert(q);
assert(state);
/* Tries to synthesize localhost RR replies where appropriate */
if (!IN_SET(*state,
DNS_TRANSACTION_RCODE_FAILURE,
DNS_TRANSACTION_NO_SERVERS,
DNS_TRANSACTION_TIMEOUT,
DNS_TRANSACTION_ATTEMPTS_MAX_REACHED,
DNS_TRANSACTION_NETWORK_DOWN))
return 0;
DNS_QUESTION_FOREACH(key, q->question_utf8) {
union in_addr_union address;
const char *name;
int af;
if (key->class != DNS_CLASS_IN &&
key->class != DNS_CLASS_ANY)
continue;
name = DNS_RESOURCE_KEY_NAME(key);
if (is_localhost(name)) {
r = synthesize_localhost_rr(q, key, &answer);
if (r < 0)
return log_error_errno(r, "Failed to synthesize localhost RRs: %m");
} else if (manager_is_own_hostname(q->manager, name)) {
r = synthesize_system_hostname_rr(q, key, &answer);
if (r < 0)
return log_error_errno(r, "Failed to synthesize system hostname RRs: %m");
} else if (is_gateway_hostname(name)) {
r = synthesize_gateway_rr(q, key, &answer);
if (r < 0)
return log_error_errno(r, "Failed to synthesize gateway RRs: %m");
} else if ((dns_name_endswith(name, "127.in-addr.arpa") > 0 && dns_name_equal(name, "2.0.0.127.in-addr.arpa") == 0) ||
dns_name_equal(name, "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa") > 0) {
r = synthesize_localhost_ptr(q, key, &answer);
if (r < 0)
return log_error_errno(r, "Failed to synthesize localhost PTR RRs: %m");
} else if (dns_name_address(name, &af, &address) > 0) {
r = synthesize_system_hostname_ptr(q, af, &address, &answer);
if (r < 0)
return log_error_errno(r, "Failed to synthesize system hostname PTR RR: %m");
r = synthesize_gateway_ptr(q, af, &address, &answer);
if (r < 0)
return log_error_errno(r, "Failed to synthesize gateway hostname PTR RR: %m");
}
}
if (!answer)
return 0;
dns_answer_unref(q->answer);
q->answer = answer;
answer = NULL;
q->answer_rcode = DNS_RCODE_SUCCESS;
q->answer_protocol = SYNTHESIZE_PROTOCOL(q->flags);
q->answer_family = SYNTHESIZE_FAMILY(q->flags);
*state = DNS_TRANSACTION_SUCCESS;
return 1;
}
int dns_query_go(DnsQuery *q) {
DnsScopeMatch found = DNS_SCOPE_NO;
DnsScope *s, *first = NULL;
DnsQueryCandidate *c;
int r;
assert(q);
if (q->state != DNS_TRANSACTION_NULL)
return 0;
LIST_FOREACH(scopes, s, q->manager->dns_scopes) {
DnsScopeMatch match;
const char *name;
name = dns_question_first_name(dns_query_question_for_protocol(q, s->protocol));
if (!name)
continue;
match = dns_scope_good_domain(s, q->ifindex, q->flags, name);
if (match < 0)
return match;
if (match == DNS_SCOPE_NO)
continue;
found = match;
if (match == DNS_SCOPE_YES) {
first = s;
break;
} else {
assert(match == DNS_SCOPE_MAYBE);
if (!first)
first = s;
}
}
if (found == DNS_SCOPE_NO) {
DnsTransactionState state = DNS_TRANSACTION_NO_SERVERS;
dns_query_synthesize_reply(q, &state);
dns_query_complete(q, state);
return 1;
}
r = dns_query_add_candidate(q, first);
if (r < 0)
goto fail;
LIST_FOREACH(scopes, s, first->scopes_next) {
DnsScopeMatch match;
const char *name;
name = dns_question_first_name(dns_query_question_for_protocol(q, s->protocol));
if (!name)
continue;
match = dns_scope_good_domain(s, q->ifindex, q->flags, name);
if (match < 0)
goto fail;
if (match != found)
continue;
r = dns_query_add_candidate(q, s);
if (r < 0)
goto fail;
}
q->answer = dns_answer_unref(q->answer);
q->answer_rcode = 0;
q->answer_family = AF_UNSPEC;
q->answer_protocol = _DNS_PROTOCOL_INVALID;
r = sd_event_add_time(
q->manager->event,
&q->timeout_event_source,
clock_boottime_or_monotonic(),
now(clock_boottime_or_monotonic()) + QUERY_TIMEOUT_USEC, 0,
on_query_timeout, q);
if (r < 0)
goto fail;
(void) sd_event_source_set_description(q->timeout_event_source, "query-timeout");
q->state = DNS_TRANSACTION_PENDING;
q->block_ready++;
/* Start the transactions */
LIST_FOREACH(candidates_by_query, c, q->candidates) {
r = dns_query_candidate_go(c);
if (r < 0) {
q->block_ready--;
goto fail;
}
}
q->block_ready--;
dns_query_ready(q);
return 1;
fail:
dns_query_stop(q);
return r;
}
static void dns_query_accept(DnsQuery *q, DnsQueryCandidate *c) {
DnsTransactionState state = DNS_TRANSACTION_NO_SERVERS;
bool has_authenticated = false, has_non_authenticated = false;
DnssecResult dnssec_result_authenticated = _DNSSEC_RESULT_INVALID, dnssec_result_non_authenticated = _DNSSEC_RESULT_INVALID;
DnsTransaction *t;
Iterator i;
int r;
assert(q);
if (!c) {
dns_query_synthesize_reply(q, &state);
dns_query_complete(q, state);
return;
}
SET_FOREACH(t, c->transactions, i) {
switch (t->state) {
case DNS_TRANSACTION_SUCCESS: {
/* We found a successfuly reply, merge it into the answer */
r = dns_answer_extend(&q->answer, t->answer);
if (r < 0) {
dns_query_complete(q, DNS_TRANSACTION_RESOURCES);
return;
}
q->answer_rcode = t->answer_rcode;
if (t->answer_authenticated) {
has_authenticated = true;
dnssec_result_authenticated = t->answer_dnssec_result;
} else {
has_non_authenticated = true;
dnssec_result_non_authenticated = t->answer_dnssec_result;
}
state = DNS_TRANSACTION_SUCCESS;
break;
}
case DNS_TRANSACTION_NULL:
case DNS_TRANSACTION_PENDING:
case DNS_TRANSACTION_VALIDATING:
case DNS_TRANSACTION_ABORTED:
/* Ignore transactions that didn't complete */
continue;
default:
/* Any kind of failure? Store the data away,
* if there's nothing stored yet. */
if (state == DNS_TRANSACTION_SUCCESS)
continue;
q->answer = dns_answer_unref(q->answer);
q->answer_rcode = t->answer_rcode;
q->answer_dnssec_result = t->answer_dnssec_result;
state = t->state;
break;
}
}
if (state == DNS_TRANSACTION_SUCCESS) {
q->answer_authenticated = has_authenticated && !has_non_authenticated;
q->answer_dnssec_result = q->answer_authenticated ? dnssec_result_authenticated : dnssec_result_non_authenticated;
}
q->answer_protocol = c->scope->protocol;
q->answer_family = c->scope->family;
dns_search_domain_unref(q->answer_search_domain);
q->answer_search_domain = dns_search_domain_ref(c->search_domain);
dns_query_synthesize_reply(q, &state);
dns_query_complete(q, state);
}
void dns_query_ready(DnsQuery *q) {
DnsQueryCandidate *bad = NULL, *c;
bool pending = false;
assert(q);
assert(DNS_TRANSACTION_IS_LIVE(q->state));
/* Note that this call might invalidate the query. Callers
* should hence not attempt to access the query or transaction
* after calling this function, unless the block_ready
* counter was explicitly bumped before doing so. */
if (q->block_ready > 0)
return;
LIST_FOREACH(candidates_by_query, c, q->candidates) {
DnsTransactionState state;
state = dns_query_candidate_state(c);
switch (state) {
case DNS_TRANSACTION_SUCCESS:
/* One of the candidates is successful,
* let's use it, and copy its data out */
dns_query_accept(q, c);
return;
case DNS_TRANSACTION_NULL:
case DNS_TRANSACTION_PENDING:
case DNS_TRANSACTION_VALIDATING:
/* One of the candidates is still going on,
* let's maybe wait for it */
pending = true;
break;
default:
/* Any kind of failure */
bad = c;
break;
}
}
if (pending)
return;
dns_query_accept(q, bad);
}
static int dns_query_cname_redirect(DnsQuery *q, const DnsResourceRecord *cname) {
_cleanup_(dns_question_unrefp) DnsQuestion *nq_idna = NULL, *nq_utf8 = NULL;
int r, k;
assert(q);
q->n_cname_redirects ++;
if (q->n_cname_redirects > CNAME_MAX)
return -ELOOP;
r = dns_question_cname_redirect(q->question_idna, cname, &nq_idna);
if (r < 0)
return r;
else if (r > 0)
log_debug("Following CNAME/DNAME %s → %s.", dns_question_first_name(q->question_idna), dns_question_first_name(nq_idna));
k = dns_question_is_equal(q->question_idna, q->question_utf8);
if (k < 0)
return r;
if (k > 0) {
/* Same question? Shortcut new question generation */
nq_utf8 = dns_question_ref(nq_idna);
k = r;
} else {
k = dns_question_cname_redirect(q->question_utf8, cname, &nq_utf8);
if (k < 0)
return k;
else if (k > 0)
log_debug("Following UTF8 CNAME/DNAME %s → %s.", dns_question_first_name(q->question_utf8), dns_question_first_name(nq_utf8));
}
if (r == 0 && k == 0) /* No actual cname happened? */
return -ELOOP;
dns_question_unref(q->question_idna);
q->question_idna = nq_idna;
nq_idna = NULL;
dns_question_unref(q->question_utf8);
q->question_utf8 = nq_utf8;
nq_utf8 = NULL;
dns_query_free_candidates(q);
dns_query_reset_answer(q);
q->state = DNS_TRANSACTION_NULL;
/* Turn off searching for the new name */
q->flags |= SD_RESOLVED_NO_SEARCH;
return 0;
}
int dns_query_process_cname(DnsQuery *q) {
_cleanup_(dns_resource_record_unrefp) DnsResourceRecord *cname = NULL;
DnsQuestion *question;
DnsResourceRecord *rr;
int r;
assert(q);
if (!IN_SET(q->state, DNS_TRANSACTION_SUCCESS, DNS_TRANSACTION_NULL))
return DNS_QUERY_NOMATCH;
question = dns_query_question_for_protocol(q, q->answer_protocol);
DNS_ANSWER_FOREACH(rr, q->answer) {
r = dns_question_matches_rr(question, rr, DNS_SEARCH_DOMAIN_NAME(q->answer_search_domain));
if (r < 0)
return r;
if (r > 0)
return DNS_QUERY_MATCH; /* The answer matches directly, no need to follow cnames */
r = dns_question_matches_cname_or_dname(question, rr, DNS_SEARCH_DOMAIN_NAME(q->answer_search_domain));
if (r < 0)
return r;
if (r > 0 && !cname)
cname = dns_resource_record_ref(rr);
}
if (!cname)
return DNS_QUERY_NOMATCH; /* No match and no cname to follow */
if (q->flags & SD_RESOLVED_NO_CNAME)
return -ELOOP;
/* OK, let's actually follow the CNAME */
r = dns_query_cname_redirect(q, cname);
if (r < 0)
return r;
/* Let's see if the answer can already answer the new
* redirected question */
r = dns_query_process_cname(q);
if (r != DNS_QUERY_NOMATCH)
return r;
/* OK, it cannot, let's begin with the new query */
r = dns_query_go(q);
if (r < 0)
return r;
return DNS_QUERY_RESTARTED; /* We restarted the query for a new cname */
}
static int on_bus_track(sd_bus_track *t, void *userdata) {
DnsQuery *q = userdata;
assert(t);
assert(q);
log_debug("Client of active query vanished, aborting query.");
dns_query_complete(q, DNS_TRANSACTION_ABORTED);
return 0;
}
int dns_query_bus_track(DnsQuery *q, sd_bus_message *m) {
int r;
assert(q);
assert(m);
if (!q->bus_track) {
r = sd_bus_track_new(sd_bus_message_get_bus(m), &q->bus_track, on_bus_track, q);
if (r < 0)
return r;
}
r = sd_bus_track_add_sender(q->bus_track, m);
if (r < 0)
return r;
return 0;
}
DnsQuestion* dns_query_question_for_protocol(DnsQuery *q, DnsProtocol protocol) {
assert(q);
switch (protocol) {
case DNS_PROTOCOL_DNS:
return q->question_idna;
case DNS_PROTOCOL_MDNS:
case DNS_PROTOCOL_LLMNR:
return q->question_utf8;
default:
return NULL;
}
}
const char *dns_query_string(DnsQuery *q) {
const char *name;
int r;
/* Returns a somewhat useful human-readable lookup key string for this query */
if (q->request_address_string)
return q->request_address_string;
if (q->request_address_valid) {
r = in_addr_to_string(q->request_family, &q->request_address, &q->request_address_string);
if (r >= 0)
return q->request_address_string;
}
name = dns_question_first_name(q->question_utf8);
if (name)
return name;
return dns_question_first_name(q->question_idna);
}
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