resolved-dns-question.c revision 23b298bce75a0d1f4f15f34458af9678b4a30c3a
/*-*- 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 "dns-type.h"
#include "resolved-dns-question.h"
DnsQuestion *dns_question_new(unsigned n) {
DnsQuestion *q;
assert(n > 0);
q = malloc0(offsetof(DnsQuestion, keys) + sizeof(DnsResourceKey*) * n);
if (!q)
return NULL;
q->n_ref = 1;
q->n_allocated = n;
return q;
}
DnsQuestion *dns_question_ref(DnsQuestion *q) {
if (!q)
return NULL;
assert(q->n_ref > 0);
q->n_ref++;
return q;
}
DnsQuestion *dns_question_unref(DnsQuestion *q) {
if (!q)
return NULL;
assert(q->n_ref > 0);
if (q->n_ref == 1) {
unsigned i;
for (i = 0; i < q->n_keys; i++)
dns_resource_key_unref(q->keys[i]);
free(q);
} else
q->n_ref--;
return NULL;
}
int dns_question_add(DnsQuestion *q, DnsResourceKey *key) {
unsigned i;
int r;
assert(key);
if (!q)
return -ENOSPC;
for (i = 0; i < q->n_keys; i++) {
r = dns_resource_key_equal(q->keys[i], key);
if (r < 0)
return r;
if (r > 0)
return 0;
}
if (q->n_keys >= q->n_allocated)
return -ENOSPC;
q->keys[q->n_keys++] = dns_resource_key_ref(key);
return 0;
}
int dns_question_matches_rr(DnsQuestion *q, DnsResourceRecord *rr, const char *search_domain) {
unsigned i;
int r;
assert(rr);
if (!q)
return 0;
for (i = 0; i < q->n_keys; i++) {
r = dns_resource_key_match_rr(q->keys[i], rr, search_domain);
if (r != 0)
return r;
}
return 0;
}
int dns_question_matches_cname(DnsQuestion *q, DnsResourceRecord *rr, const char *search_domain) {
unsigned i;
int r;
assert(rr);
if (!q)
return 0;
for (i = 0; i < q->n_keys; i++) {
r = dns_resource_key_match_cname_or_dname(q->keys[i], rr->key, search_domain);
if (r != 0)
return r;
}
return 0;
}
int dns_question_is_valid_for_query(DnsQuestion *q) {
const char *name;
unsigned i;
int r;
if (!q)
return 0;
if (q->n_keys <= 0)
return 0;
if (q->n_keys > 65535)
return 0;
name = DNS_RESOURCE_KEY_NAME(q->keys[0]);
if (!name)
return 0;
/* Check that all keys in this question bear the same name */
for (i = 0; i < q->n_keys; i++) {
assert(q->keys[i]);
if (i > 0) {
r = dns_name_equal(DNS_RESOURCE_KEY_NAME(q->keys[i]), name);
if (r <= 0)
return r;
}
if (!dns_type_is_valid_query(q->keys[i]->type))
return 0;
}
return 1;
}
int dns_question_contains(DnsQuestion *a, const DnsResourceKey *k) {
unsigned j;
int r;
assert(k);
if (!a)
return 0;
for (j = 0; j < a->n_keys; j++) {
r = dns_resource_key_equal(a->keys[j], k);
if (r != 0)
return r;
}
return 0;
}
int dns_question_is_equal(DnsQuestion *a, DnsQuestion *b) {
unsigned j;
int r;
if (a == b)
return 1;
if (!a)
return !b || b->n_keys == 0;
if (!b)
return a->n_keys == 0;
/* Checks if all keys in a are also contained b, and vice versa */
for (j = 0; j < a->n_keys; j++) {
r = dns_question_contains(b, a->keys[j]);
if (r <= 0)
return r;
}
for (j = 0; j < b->n_keys; j++) {
r = dns_question_contains(a, b->keys[j]);
if (r <= 0)
return r;
}
return 1;
}
int dns_question_cname_redirect(DnsQuestion *q, const DnsResourceRecord *cname, DnsQuestion **ret) {
_cleanup_(dns_question_unrefp) DnsQuestion *n = NULL;
DnsResourceKey *key;
bool same = true;
int r;
assert(cname);
assert(ret);
assert(IN_SET(cname->key->type, DNS_TYPE_CNAME, DNS_TYPE_DNAME));
if (dns_question_size(q) <= 0) {
*ret = NULL;
return 0;
}
DNS_QUESTION_FOREACH(key, q) {
_cleanup_free_ char *destination = NULL;
const char *d;
if (cname->key->type == DNS_TYPE_CNAME)
d = cname->cname.name;
else {
r = dns_name_change_suffix(DNS_RESOURCE_KEY_NAME(key), DNS_RESOURCE_KEY_NAME(cname->key), cname->dname.name, &destination);
if (r < 0)
return r;
if (r == 0)
continue;
d = destination;
}
r = dns_name_equal(DNS_RESOURCE_KEY_NAME(key), d);
if (r < 0)
return r;
if (r == 0) {
same = false;
break;
}
}
/* Fully the same, indicate we didn't do a thing */
if (same) {
*ret = NULL;
return 0;
}
n = dns_question_new(q->n_keys);
if (!n)
return -ENOMEM;
/* Create a new question, and patch in the new name */
DNS_QUESTION_FOREACH(key, q) {
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *k = NULL;
k = dns_resource_key_new_redirect(key, cname);
if (!k)
return -ENOMEM;
r = dns_question_add(n, k);
if (r < 0)
return r;
}
*ret = n;
n = NULL;
return 1;
}
const char *dns_question_first_name(DnsQuestion *q) {
if (!q)
return NULL;
if (q->n_keys < 1)
return NULL;
return DNS_RESOURCE_KEY_NAME(q->keys[0]);
}
int dns_question_new_address(DnsQuestion **ret, int family, const char *name, bool convert_idna) {
_cleanup_(dns_question_unrefp) DnsQuestion *q = NULL;
_cleanup_free_ char *buf = NULL;
int r;
assert(ret);
assert(name);
if (!IN_SET(family, AF_INET, AF_INET6, AF_UNSPEC))
return -EAFNOSUPPORT;
if (convert_idna) {
r = dns_name_apply_idna(name, &buf);
if (r < 0)
return r;
name = buf;
}
q = dns_question_new(family == AF_UNSPEC ? 2 : 1);
if (!q)
return -ENOMEM;
if (family != AF_INET6) {
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_A, name);
if (!key)
return -ENOMEM;
r = dns_question_add(q, key);
if (r < 0)
return r;
}
if (family != AF_INET) {
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_AAAA, name);
if (!key)
return -ENOMEM;
r = dns_question_add(q, key);
if (r < 0)
return r;
}
*ret = q;
q = NULL;
return 0;
}
int dns_question_new_reverse(DnsQuestion **ret, int family, const union in_addr_union *a) {
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
_cleanup_(dns_question_unrefp) DnsQuestion *q = NULL;
_cleanup_free_ char *reverse = NULL;
int r;
assert(ret);
assert(a);
if (!IN_SET(family, AF_INET, AF_INET6, AF_UNSPEC))
return -EAFNOSUPPORT;
r = dns_name_reverse(family, a, &reverse);
if (r < 0)
return r;
q = dns_question_new(1);
if (!q)
return -ENOMEM;
key = dns_resource_key_new_consume(DNS_CLASS_IN, DNS_TYPE_PTR, reverse);
if (!key)
return -ENOMEM;
reverse = NULL;
r = dns_question_add(q, key);
if (r < 0)
return r;
*ret = q;
q = NULL;
return 0;
}
int dns_question_new_service(
DnsQuestion **ret,
const char *service,
const char *type,
const char *domain,
bool with_txt,
bool convert_idna) {
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
_cleanup_(dns_question_unrefp) DnsQuestion *q = NULL;
_cleanup_free_ char *buf = NULL, *joined = NULL;
const char *name;
int r;
assert(ret);
/* We support three modes of invocation:
*
* 1. Only a domain is specified, in which case we assume a properly encoded SRV RR name, including service
* type and possibly a service name. If specified in this way we assume it's already IDNA converted if
* that's necessary.
*
* 2. Both service type and a domain specified, in which case a normal SRV RR is assumed, without a DNS-SD
* style prefix. In this case we'll IDNA convert the domain, if that's requested.
*
* 3. All three of service name, type and domain are specified, in which case a DNS-SD service is put
* together. The service name is never IDNA converted, and the domain is if requested.
*
* It's not supported to specify a service name without a type, or no domain name.
*/
if (!domain)
return -EINVAL;
if (type) {
if (convert_idna) {
r = dns_name_apply_idna(domain, &buf);
if (r < 0)
return r;
domain = buf;
}
r = dns_service_join(service, type, domain, &joined);
if (r < 0)
return r;
name = joined;
} else {
if (service)
return -EINVAL;
name = domain;
}
q = dns_question_new(1 + with_txt);
if (!q)
return -ENOMEM;
key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_SRV, name);
if (!key)
return -ENOMEM;
r = dns_question_add(q, key);
if (r < 0)
return r;
if (with_txt) {
dns_resource_key_unref(key);
key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_TXT, name);
if (!key)
return -ENOMEM;
r = dns_question_add(q, key);
if (r < 0)
return r;
}
*ret = q;
q = NULL;
return 0;
}