448 lines
12 KiB
C
448 lines
12 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#include "alloc-util.h"
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#include "dns-domain.h"
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#include "dns-type.h"
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#include "resolved-dns-question.h"
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DnsQuestion *dns_question_new(size_t n) {
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DnsQuestion *q;
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if (n > UINT16_MAX) /* We can only place 64K key in an question section at max */
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n = UINT16_MAX;
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q = malloc0(offsetof(DnsQuestion, keys) + sizeof(DnsResourceKey*) * n);
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if (!q)
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return NULL;
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q->n_ref = 1;
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q->n_allocated = n;
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return q;
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}
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static DnsQuestion *dns_question_free(DnsQuestion *q) {
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size_t i;
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assert(q);
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for (i = 0; i < q->n_keys; i++)
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dns_resource_key_unref(q->keys[i]);
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return mfree(q);
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}
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DEFINE_TRIVIAL_REF_UNREF_FUNC(DnsQuestion, dns_question, dns_question_free);
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int dns_question_add_raw(DnsQuestion *q, DnsResourceKey *key) {
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/* Insert without checking for duplicates. */
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assert(key);
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assert(q);
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if (q->n_keys >= q->n_allocated)
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return -ENOSPC;
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q->keys[q->n_keys++] = dns_resource_key_ref(key);
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return 0;
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}
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int dns_question_add(DnsQuestion *q, DnsResourceKey *key) {
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int r;
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assert(key);
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if (!q)
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return -ENOSPC;
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for (size_t i = 0; i < q->n_keys; i++) {
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r = dns_resource_key_equal(q->keys[i], key);
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if (r < 0)
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return r;
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if (r > 0)
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return 0;
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}
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return dns_question_add_raw(q, key);
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}
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int dns_question_matches_rr(DnsQuestion *q, DnsResourceRecord *rr, const char *search_domain) {
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size_t i;
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int r;
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assert(rr);
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if (!q)
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return 0;
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for (i = 0; i < q->n_keys; i++) {
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r = dns_resource_key_match_rr(q->keys[i], rr, search_domain);
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if (r != 0)
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return r;
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}
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return 0;
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}
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int dns_question_matches_cname_or_dname(DnsQuestion *q, DnsResourceRecord *rr, const char *search_domain) {
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size_t i;
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int r;
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assert(rr);
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if (!q)
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return 0;
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if (!IN_SET(rr->key->type, DNS_TYPE_CNAME, DNS_TYPE_DNAME))
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return 0;
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for (i = 0; i < q->n_keys; i++) {
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/* For a {C,D}NAME record we can never find a matching {C,D}NAME record */
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if (!dns_type_may_redirect(q->keys[i]->type))
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return 0;
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r = dns_resource_key_match_cname_or_dname(q->keys[i], rr->key, search_domain);
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if (r != 0)
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return r;
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}
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return 0;
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}
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int dns_question_is_valid_for_query(DnsQuestion *q) {
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const char *name;
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size_t i;
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int r;
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if (!q)
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return 0;
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if (q->n_keys <= 0)
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return 0;
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if (q->n_keys > 65535)
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return 0;
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name = dns_resource_key_name(q->keys[0]);
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if (!name)
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return 0;
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/* Check that all keys in this question bear the same name */
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for (i = 0; i < q->n_keys; i++) {
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assert(q->keys[i]);
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if (i > 0) {
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r = dns_name_equal(dns_resource_key_name(q->keys[i]), name);
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if (r <= 0)
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return r;
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}
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if (!dns_type_is_valid_query(q->keys[i]->type))
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return 0;
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}
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return 1;
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}
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int dns_question_contains(DnsQuestion *a, const DnsResourceKey *k) {
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size_t j;
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int r;
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assert(k);
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if (!a)
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return 0;
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for (j = 0; j < a->n_keys; j++) {
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r = dns_resource_key_equal(a->keys[j], k);
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if (r != 0)
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return r;
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}
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return 0;
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}
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int dns_question_is_equal(DnsQuestion *a, DnsQuestion *b) {
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size_t j;
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int r;
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if (a == b)
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return 1;
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if (!a)
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return !b || b->n_keys == 0;
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if (!b)
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return a->n_keys == 0;
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/* Checks if all keys in a are also contained b, and vice versa */
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for (j = 0; j < a->n_keys; j++) {
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r = dns_question_contains(b, a->keys[j]);
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if (r <= 0)
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return r;
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}
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for (j = 0; j < b->n_keys; j++) {
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r = dns_question_contains(a, b->keys[j]);
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if (r <= 0)
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return r;
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}
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return 1;
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}
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int dns_question_cname_redirect(DnsQuestion *q, const DnsResourceRecord *cname, DnsQuestion **ret) {
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_cleanup_(dns_question_unrefp) DnsQuestion *n = NULL;
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DnsResourceKey *key;
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bool same = true;
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int r;
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assert(cname);
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assert(ret);
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assert(IN_SET(cname->key->type, DNS_TYPE_CNAME, DNS_TYPE_DNAME));
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if (dns_question_size(q) <= 0) {
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*ret = NULL;
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return 0;
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}
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DNS_QUESTION_FOREACH(key, q) {
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_cleanup_free_ char *destination = NULL;
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const char *d;
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if (cname->key->type == DNS_TYPE_CNAME)
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d = cname->cname.name;
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else {
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r = dns_name_change_suffix(dns_resource_key_name(key), dns_resource_key_name(cname->key), cname->dname.name, &destination);
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if (r < 0)
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return r;
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if (r == 0)
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continue;
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d = destination;
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}
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r = dns_name_equal(dns_resource_key_name(key), d);
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if (r < 0)
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return r;
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if (r == 0) {
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same = false;
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break;
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}
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}
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/* Fully the same, indicate we didn't do a thing */
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if (same) {
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*ret = NULL;
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return 0;
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}
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n = dns_question_new(q->n_keys);
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if (!n)
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return -ENOMEM;
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/* Create a new question, and patch in the new name */
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DNS_QUESTION_FOREACH(key, q) {
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_cleanup_(dns_resource_key_unrefp) DnsResourceKey *k = NULL;
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k = dns_resource_key_new_redirect(key, cname);
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if (!k)
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return -ENOMEM;
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r = dns_question_add(n, k);
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if (r < 0)
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return r;
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}
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*ret = TAKE_PTR(n);
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return 1;
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}
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const char *dns_question_first_name(DnsQuestion *q) {
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if (!q)
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return NULL;
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if (q->n_keys < 1)
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return NULL;
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return dns_resource_key_name(q->keys[0]);
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}
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int dns_question_new_address(DnsQuestion **ret, int family, const char *name, bool convert_idna) {
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_cleanup_(dns_question_unrefp) DnsQuestion *q = NULL;
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_cleanup_free_ char *buf = NULL;
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int r;
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assert(ret);
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assert(name);
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if (!IN_SET(family, AF_INET, AF_INET6, AF_UNSPEC))
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return -EAFNOSUPPORT;
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if (convert_idna) {
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r = dns_name_apply_idna(name, &buf);
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if (r < 0)
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return r;
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if (r > 0 && !streq(name, buf))
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name = buf;
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else
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/* We did not manage to create convert the idna name, or it's
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* the same as the original name. We assume the caller already
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* created an unconverted question, so let's not repeat work
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* unnecessarily. */
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return -EALREADY;
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}
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q = dns_question_new(family == AF_UNSPEC ? 2 : 1);
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if (!q)
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return -ENOMEM;
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if (family != AF_INET6) {
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_cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
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key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_A, name);
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if (!key)
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return -ENOMEM;
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r = dns_question_add(q, key);
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if (r < 0)
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return r;
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}
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if (family != AF_INET) {
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_cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
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key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_AAAA, name);
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if (!key)
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return -ENOMEM;
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r = dns_question_add(q, key);
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if (r < 0)
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return r;
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}
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*ret = TAKE_PTR(q);
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return 0;
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}
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int dns_question_new_reverse(DnsQuestion **ret, int family, const union in_addr_union *a) {
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_cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
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_cleanup_(dns_question_unrefp) DnsQuestion *q = NULL;
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_cleanup_free_ char *reverse = NULL;
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int r;
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assert(ret);
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assert(a);
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if (!IN_SET(family, AF_INET, AF_INET6, AF_UNSPEC))
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return -EAFNOSUPPORT;
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r = dns_name_reverse(family, a, &reverse);
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if (r < 0)
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return r;
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q = dns_question_new(1);
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if (!q)
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return -ENOMEM;
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key = dns_resource_key_new_consume(DNS_CLASS_IN, DNS_TYPE_PTR, reverse);
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if (!key)
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return -ENOMEM;
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reverse = NULL;
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r = dns_question_add(q, key);
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if (r < 0)
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return r;
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*ret = TAKE_PTR(q);
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return 0;
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}
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int dns_question_new_service(
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DnsQuestion **ret,
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const char *service,
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const char *type,
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const char *domain,
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bool with_txt,
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bool convert_idna) {
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_cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
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_cleanup_(dns_question_unrefp) DnsQuestion *q = NULL;
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_cleanup_free_ char *buf = NULL, *joined = NULL;
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const char *name;
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int r;
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assert(ret);
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/* We support three modes of invocation:
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*
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* 1. Only a domain is specified, in which case we assume a properly encoded SRV RR name, including service
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* type and possibly a service name. If specified in this way we assume it's already IDNA converted if
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* that's necessary.
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*
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* 2. Both service type and a domain specified, in which case a normal SRV RR is assumed, without a DNS-SD
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* style prefix. In this case we'll IDNA convert the domain, if that's requested.
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*
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* 3. All three of service name, type and domain are specified, in which case a DNS-SD service is put
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* together. The service name is never IDNA converted, and the domain is if requested.
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*
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* It's not supported to specify a service name without a type, or no domain name.
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*/
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if (!domain)
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return -EINVAL;
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if (type) {
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if (convert_idna) {
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r = dns_name_apply_idna(domain, &buf);
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if (r < 0)
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return r;
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if (r > 0)
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domain = buf;
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}
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r = dns_service_join(service, type, domain, &joined);
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if (r < 0)
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return r;
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name = joined;
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} else {
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if (service)
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return -EINVAL;
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name = domain;
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}
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q = dns_question_new(1 + with_txt);
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if (!q)
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return -ENOMEM;
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key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_SRV, name);
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if (!key)
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return -ENOMEM;
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r = dns_question_add(q, key);
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if (r < 0)
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return r;
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if (with_txt) {
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dns_resource_key_unref(key);
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key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_TXT, name);
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if (!key)
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return -ENOMEM;
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r = dns_question_add(q, key);
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if (r < 0)
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return r;
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}
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*ret = TAKE_PTR(q);
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return 0;
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}
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