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-rw-r--r--src/resolve/resolved-dns-answer.c771
1 files changed, 771 insertions, 0 deletions
diff --git a/src/resolve/resolved-dns-answer.c b/src/resolve/resolved-dns-answer.c
new file mode 100644
index 0000000..5b762a8
--- /dev/null
+++ b/src/resolve/resolved-dns-answer.c
@@ -0,0 +1,771 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <stdio.h>
+
+#include "alloc-util.h"
+#include "dns-domain.h"
+#include "resolved-dns-answer.h"
+#include "resolved-dns-dnssec.h"
+#include "string-util.h"
+
+DnsAnswer *dns_answer_new(size_t n) {
+ DnsAnswer *a;
+
+ if (n > UINT16_MAX) /* We can only place 64K RRs in an answer at max */
+ n = UINT16_MAX;
+
+ a = malloc0(offsetof(DnsAnswer, items) + sizeof(DnsAnswerItem) * n);
+ if (!a)
+ return NULL;
+
+ a->n_ref = 1;
+ a->n_allocated = n;
+
+ return a;
+}
+
+static void dns_answer_flush(DnsAnswer *a) {
+ DnsResourceRecord *rr;
+
+ if (!a)
+ return;
+
+ DNS_ANSWER_FOREACH(rr, a)
+ dns_resource_record_unref(rr);
+
+ a->n_rrs = 0;
+}
+
+static DnsAnswer *dns_answer_free(DnsAnswer *a) {
+ assert(a);
+
+ dns_answer_flush(a);
+ return mfree(a);
+}
+
+DEFINE_TRIVIAL_REF_UNREF_FUNC(DnsAnswer, dns_answer, dns_answer_free);
+
+static int dns_answer_add_raw(DnsAnswer *a, DnsResourceRecord *rr, int ifindex, DnsAnswerFlags flags) {
+ assert(rr);
+
+ if (!a)
+ return -ENOSPC;
+
+ if (a->n_rrs >= a->n_allocated)
+ return -ENOSPC;
+
+ a->items[a->n_rrs++] = (DnsAnswerItem) {
+ .rr = dns_resource_record_ref(rr),
+ .ifindex = ifindex,
+ .flags = flags,
+ };
+
+ return 1;
+}
+
+static int dns_answer_add_raw_all(DnsAnswer *a, DnsAnswer *source) {
+ DnsResourceRecord *rr;
+ DnsAnswerFlags flags;
+ int ifindex, r;
+
+ DNS_ANSWER_FOREACH_FULL(rr, ifindex, flags, source) {
+ r = dns_answer_add_raw(a, rr, ifindex, flags);
+ if (r < 0)
+ return r;
+ }
+
+ return 0;
+}
+
+int dns_answer_add(DnsAnswer *a, DnsResourceRecord *rr, int ifindex, DnsAnswerFlags flags) {
+ size_t i;
+ int r;
+
+ assert(rr);
+
+ if (!a)
+ return -ENOSPC;
+ if (a->n_ref > 1)
+ return -EBUSY;
+
+ for (i = 0; i < a->n_rrs; i++) {
+ if (a->items[i].ifindex != ifindex)
+ continue;
+
+ r = dns_resource_key_equal(a->items[i].rr->key, rr->key);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ continue;
+
+ /* There's already an RR of the same RRset in place! Let's see if the TTLs more or less
+ * match. We don't really care if they match precisely, but we do care whether one is 0 and
+ * the other is not. See RFC 2181, Section 5.2. */
+ if ((rr->ttl == 0) != (a->items[i].rr->ttl == 0))
+ return -EINVAL;
+
+ r = dns_resource_record_payload_equal(a->items[i].rr, rr);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ continue;
+
+ /* Entry already exists, keep the entry with the higher RR. */
+ if (rr->ttl > a->items[i].rr->ttl) {
+ dns_resource_record_ref(rr);
+ dns_resource_record_unref(a->items[i].rr);
+ a->items[i].rr = rr;
+ }
+
+ a->items[i].flags |= flags;
+ return 0;
+ }
+
+ return dns_answer_add_raw(a, rr, ifindex, flags);
+}
+
+static int dns_answer_add_all(DnsAnswer *a, DnsAnswer *b) {
+ DnsResourceRecord *rr;
+ DnsAnswerFlags flags;
+ int ifindex, r;
+
+ DNS_ANSWER_FOREACH_FULL(rr, ifindex, flags, b) {
+ r = dns_answer_add(a, rr, ifindex, flags);
+ if (r < 0)
+ return r;
+ }
+
+ return 0;
+}
+
+int dns_answer_add_extend(DnsAnswer **a, DnsResourceRecord *rr, int ifindex, DnsAnswerFlags flags) {
+ int r;
+
+ assert(a);
+ assert(rr);
+
+ r = dns_answer_reserve_or_clone(a, 1);
+ if (r < 0)
+ return r;
+
+ return dns_answer_add(*a, rr, ifindex, flags);
+}
+
+int dns_answer_add_soa(DnsAnswer *a, const char *name, uint32_t ttl, int ifindex) {
+ _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *soa = NULL;
+
+ soa = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_SOA, name);
+ if (!soa)
+ return -ENOMEM;
+
+ soa->ttl = ttl;
+
+ soa->soa.mname = strdup(name);
+ if (!soa->soa.mname)
+ return -ENOMEM;
+
+ soa->soa.rname = strjoin("root.", name);
+ if (!soa->soa.rname)
+ return -ENOMEM;
+
+ soa->soa.serial = 1;
+ soa->soa.refresh = 1;
+ soa->soa.retry = 1;
+ soa->soa.expire = 1;
+ soa->soa.minimum = ttl;
+
+ return dns_answer_add(a, soa, ifindex, DNS_ANSWER_AUTHENTICATED);
+}
+
+int dns_answer_match_key(DnsAnswer *a, const DnsResourceKey *key, DnsAnswerFlags *ret_flags) {
+ DnsAnswerFlags flags = 0, i_flags;
+ DnsResourceRecord *i;
+ bool found = false;
+ int r;
+
+ assert(key);
+
+ DNS_ANSWER_FOREACH_FLAGS(i, i_flags, a) {
+ r = dns_resource_key_match_rr(key, i, NULL);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ continue;
+
+ if (!ret_flags)
+ return 1;
+
+ if (found)
+ flags &= i_flags;
+ else {
+ flags = i_flags;
+ found = true;
+ }
+ }
+
+ if (ret_flags)
+ *ret_flags = flags;
+
+ return found;
+}
+
+int dns_answer_contains_nsec_or_nsec3(DnsAnswer *a) {
+ DnsResourceRecord *i;
+
+ DNS_ANSWER_FOREACH(i, a) {
+ if (IN_SET(i->key->type, DNS_TYPE_NSEC, DNS_TYPE_NSEC3))
+ return true;
+ }
+
+ return false;
+}
+
+int dns_answer_contains_zone_nsec3(DnsAnswer *answer, const char *zone) {
+ DnsResourceRecord *rr;
+ int r;
+
+ /* Checks whether the specified answer contains at least one NSEC3 RR in the specified zone */
+
+ DNS_ANSWER_FOREACH(rr, answer) {
+ const char *p;
+
+ if (rr->key->type != DNS_TYPE_NSEC3)
+ continue;
+
+ p = dns_resource_key_name(rr->key);
+ r = dns_name_parent(&p);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ continue;
+
+ r = dns_name_equal(p, zone);
+ if (r != 0)
+ return r;
+ }
+
+ return false;
+}
+
+int dns_answer_find_soa(DnsAnswer *a, const DnsResourceKey *key, DnsResourceRecord **ret, DnsAnswerFlags *flags) {
+ DnsResourceRecord *rr, *soa = NULL;
+ DnsAnswerFlags rr_flags, soa_flags = 0;
+ int r;
+
+ assert(key);
+
+ /* For a SOA record we can never find a matching SOA record */
+ if (key->type == DNS_TYPE_SOA)
+ return 0;
+
+ DNS_ANSWER_FOREACH_FLAGS(rr, rr_flags, a) {
+ r = dns_resource_key_match_soa(key, rr->key);
+ if (r < 0)
+ return r;
+ if (r > 0) {
+
+ if (soa) {
+ r = dns_name_endswith(dns_resource_key_name(rr->key), dns_resource_key_name(soa->key));
+ if (r < 0)
+ return r;
+ if (r > 0)
+ continue;
+ }
+
+ soa = rr;
+ soa_flags = rr_flags;
+ }
+ }
+
+ if (!soa)
+ return 0;
+
+ if (ret)
+ *ret = soa;
+ if (flags)
+ *flags = soa_flags;
+
+ return 1;
+}
+
+int dns_answer_find_cname_or_dname(DnsAnswer *a, const DnsResourceKey *key, DnsResourceRecord **ret, DnsAnswerFlags *flags) {
+ DnsResourceRecord *rr;
+ DnsAnswerFlags rr_flags;
+ int r;
+
+ assert(key);
+
+ /* For a {C,D}NAME record we can never find a matching {C,D}NAME record */
+ if (!dns_type_may_redirect(key->type))
+ return 0;
+
+ DNS_ANSWER_FOREACH_FLAGS(rr, rr_flags, a) {
+ r = dns_resource_key_match_cname_or_dname(key, rr->key, NULL);
+ if (r < 0)
+ return r;
+ if (r > 0) {
+ if (ret)
+ *ret = rr;
+ if (flags)
+ *flags = rr_flags;
+ return 1;
+ }
+ }
+
+ return 0;
+}
+
+int dns_answer_merge(DnsAnswer *a, DnsAnswer *b, DnsAnswer **ret) {
+ _cleanup_(dns_answer_unrefp) DnsAnswer *k = NULL;
+ int r;
+
+ assert(ret);
+
+ if (a == b) {
+ *ret = dns_answer_ref(a);
+ return 0;
+ }
+
+ if (dns_answer_size(a) <= 0) {
+ *ret = dns_answer_ref(b);
+ return 0;
+ }
+
+ if (dns_answer_size(b) <= 0) {
+ *ret = dns_answer_ref(a);
+ return 0;
+ }
+
+ k = dns_answer_new(a->n_rrs + b->n_rrs);
+ if (!k)
+ return -ENOMEM;
+
+ r = dns_answer_add_raw_all(k, a);
+ if (r < 0)
+ return r;
+
+ r = dns_answer_add_all(k, b);
+ if (r < 0)
+ return r;
+
+ *ret = TAKE_PTR(k);
+
+ return 0;
+}
+
+int dns_answer_extend(DnsAnswer **a, DnsAnswer *b) {
+ DnsAnswer *merged;
+ int r;
+
+ assert(a);
+
+ r = dns_answer_merge(*a, b, &merged);
+ if (r < 0)
+ return r;
+
+ dns_answer_unref(*a);
+ *a = merged;
+
+ return 0;
+}
+
+int dns_answer_remove_by_key(DnsAnswer **a, const DnsResourceKey *key) {
+ bool found = false, other = false;
+ DnsResourceRecord *rr;
+ size_t i;
+ int r;
+
+ assert(a);
+ assert(key);
+
+ /* Remove all entries matching the specified key from *a */
+
+ DNS_ANSWER_FOREACH(rr, *a) {
+ r = dns_resource_key_equal(rr->key, key);
+ if (r < 0)
+ return r;
+ if (r > 0)
+ found = true;
+ else
+ other = true;
+
+ if (found && other)
+ break;
+ }
+
+ if (!found)
+ return 0;
+
+ if (!other) {
+ *a = dns_answer_unref(*a); /* Return NULL for the empty answer */
+ return 1;
+ }
+
+ if ((*a)->n_ref > 1) {
+ _cleanup_(dns_answer_unrefp) DnsAnswer *copy = NULL;
+ DnsAnswerFlags flags;
+ int ifindex;
+
+ copy = dns_answer_new((*a)->n_rrs);
+ if (!copy)
+ return -ENOMEM;
+
+ DNS_ANSWER_FOREACH_FULL(rr, ifindex, flags, *a) {
+ r = dns_resource_key_equal(rr->key, key);
+ if (r < 0)
+ return r;
+ if (r > 0)
+ continue;
+
+ r = dns_answer_add_raw(copy, rr, ifindex, flags);
+ if (r < 0)
+ return r;
+ }
+
+ dns_answer_unref(*a);
+ *a = TAKE_PTR(copy);
+
+ return 1;
+ }
+
+ /* Only a single reference, edit in-place */
+
+ i = 0;
+ for (;;) {
+ if (i >= (*a)->n_rrs)
+ break;
+
+ r = dns_resource_key_equal((*a)->items[i].rr->key, key);
+ if (r < 0)
+ return r;
+ if (r > 0) {
+ /* Kill this entry */
+
+ dns_resource_record_unref((*a)->items[i].rr);
+ memmove((*a)->items + i, (*a)->items + i + 1, sizeof(DnsAnswerItem) * ((*a)->n_rrs - i - 1));
+ (*a)->n_rrs--;
+ continue;
+
+ } else
+ /* Keep this entry */
+ i++;
+ }
+
+ return 1;
+}
+
+int dns_answer_remove_by_rr(DnsAnswer **a, DnsResourceRecord *rm) {
+ bool found = false, other = false;
+ DnsResourceRecord *rr;
+ size_t i;
+ int r;
+
+ assert(a);
+ assert(rm);
+
+ /* Remove all entries matching the specified RR from *a */
+
+ DNS_ANSWER_FOREACH(rr, *a) {
+ r = dns_resource_record_equal(rr, rm);
+ if (r < 0)
+ return r;
+ if (r > 0)
+ found = true;
+ else
+ other = true;
+
+ if (found && other)
+ break;
+ }
+
+ if (!found)
+ return 0;
+
+ if (!other) {
+ *a = dns_answer_unref(*a); /* Return NULL for the empty answer */
+ return 1;
+ }
+
+ if ((*a)->n_ref > 1) {
+ _cleanup_(dns_answer_unrefp) DnsAnswer *copy = NULL;
+ DnsAnswerFlags flags;
+ int ifindex;
+
+ copy = dns_answer_new((*a)->n_rrs);
+ if (!copy)
+ return -ENOMEM;
+
+ DNS_ANSWER_FOREACH_FULL(rr, ifindex, flags, *a) {
+ r = dns_resource_record_equal(rr, rm);
+ if (r < 0)
+ return r;
+ if (r > 0)
+ continue;
+
+ r = dns_answer_add_raw(copy, rr, ifindex, flags);
+ if (r < 0)
+ return r;
+ }
+
+ dns_answer_unref(*a);
+ *a = TAKE_PTR(copy);
+
+ return 1;
+ }
+
+ /* Only a single reference, edit in-place */
+
+ i = 0;
+ for (;;) {
+ if (i >= (*a)->n_rrs)
+ break;
+
+ r = dns_resource_record_equal((*a)->items[i].rr, rm);
+ if (r < 0)
+ return r;
+ if (r > 0) {
+ /* Kill this entry */
+
+ dns_resource_record_unref((*a)->items[i].rr);
+ memmove((*a)->items + i, (*a)->items + i + 1, sizeof(DnsAnswerItem) * ((*a)->n_rrs - i - 1));
+ (*a)->n_rrs--;
+ continue;
+
+ } else
+ /* Keep this entry */
+ i++;
+ }
+
+ return 1;
+}
+
+int dns_answer_copy_by_key(DnsAnswer **a, DnsAnswer *source, const DnsResourceKey *key, DnsAnswerFlags or_flags) {
+ DnsResourceRecord *rr_source;
+ int ifindex_source, r;
+ DnsAnswerFlags flags_source;
+
+ assert(a);
+ assert(key);
+
+ /* Copy all RRs matching the specified key from source into *a */
+
+ DNS_ANSWER_FOREACH_FULL(rr_source, ifindex_source, flags_source, source) {
+
+ r = dns_resource_key_equal(rr_source->key, key);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ continue;
+
+ /* Make space for at least one entry */
+ r = dns_answer_reserve_or_clone(a, 1);
+ if (r < 0)
+ return r;
+
+ r = dns_answer_add(*a, rr_source, ifindex_source, flags_source|or_flags);
+ if (r < 0)
+ return r;
+ }
+
+ return 0;
+}
+
+int dns_answer_move_by_key(DnsAnswer **to, DnsAnswer **from, const DnsResourceKey *key, DnsAnswerFlags or_flags) {
+ int r;
+
+ assert(to);
+ assert(from);
+ assert(key);
+
+ r = dns_answer_copy_by_key(to, *from, key, or_flags);
+ if (r < 0)
+ return r;
+
+ return dns_answer_remove_by_key(from, key);
+}
+
+void dns_answer_order_by_scope(DnsAnswer *a, bool prefer_link_local) {
+ DnsAnswerItem *items;
+ size_t i, start, end;
+
+ if (!a)
+ return;
+
+ if (a->n_rrs <= 1)
+ return;
+
+ start = 0;
+ end = a->n_rrs-1;
+
+ /* RFC 4795, Section 2.6 suggests we should order entries
+ * depending on whether the sender is a link-local address. */
+
+ items = newa(DnsAnswerItem, a->n_rrs);
+ for (i = 0; i < a->n_rrs; i++) {
+
+ if (a->items[i].rr->key->class == DNS_CLASS_IN &&
+ ((a->items[i].rr->key->type == DNS_TYPE_A && in_addr_is_link_local(AF_INET, (union in_addr_union*) &a->items[i].rr->a.in_addr) != prefer_link_local) ||
+ (a->items[i].rr->key->type == DNS_TYPE_AAAA && in_addr_is_link_local(AF_INET6, (union in_addr_union*) &a->items[i].rr->aaaa.in6_addr) != prefer_link_local)))
+ /* Order address records that are not preferred to the end of the array */
+ items[end--] = a->items[i];
+ else
+ /* Order all other records to the beginning of the array */
+ items[start++] = a->items[i];
+ }
+
+ assert(start == end+1);
+ memcpy(a->items, items, sizeof(DnsAnswerItem) * a->n_rrs);
+}
+
+int dns_answer_reserve(DnsAnswer **a, size_t n_free) {
+ DnsAnswer *n;
+
+ assert(a);
+
+ if (n_free <= 0)
+ return 0;
+
+ if (*a) {
+ size_t ns;
+
+ if ((*a)->n_ref > 1)
+ return -EBUSY;
+
+ ns = (*a)->n_rrs + n_free;
+ if (ns > UINT16_MAX) /* Maximum number of RRs we can stick into a DNS packet section */
+ ns = UINT16_MAX;
+
+ if ((*a)->n_allocated >= ns)
+ return 0;
+
+ /* Allocate more than we need */
+ ns *= 2;
+ if (ns > UINT16_MAX)
+ ns = UINT16_MAX;
+
+ n = realloc(*a, offsetof(DnsAnswer, items) + sizeof(DnsAnswerItem) * ns);
+ if (!n)
+ return -ENOMEM;
+
+ n->n_allocated = ns;
+ } else {
+ n = dns_answer_new(n_free);
+ if (!n)
+ return -ENOMEM;
+ }
+
+ *a = n;
+ return 0;
+}
+
+int dns_answer_reserve_or_clone(DnsAnswer **a, size_t n_free) {
+ _cleanup_(dns_answer_unrefp) DnsAnswer *n = NULL;
+ int r;
+
+ assert(a);
+
+ /* Tries to extend the DnsAnswer object. And if that's not
+ * possible, since we are not the sole owner, then allocate a
+ * new, appropriately sized one. Either way, after this call
+ * the object will only have a single reference, and has room
+ * for at least the specified number of RRs. */
+
+ r = dns_answer_reserve(a, n_free);
+ if (r != -EBUSY)
+ return r;
+
+ assert(*a);
+
+ n = dns_answer_new(((*a)->n_rrs + n_free) * 2);
+ if (!n)
+ return -ENOMEM;
+
+ r = dns_answer_add_raw_all(n, *a);
+ if (r < 0)
+ return r;
+
+ dns_answer_unref(*a);
+ *a = TAKE_PTR(n);
+
+ return 0;
+}
+
+/*
+ * This function is not used in the code base, but is useful when debugging. Do not delete.
+ */
+void dns_answer_dump(DnsAnswer *answer, FILE *f) {
+ DnsResourceRecord *rr;
+ DnsAnswerFlags flags;
+ int ifindex;
+
+ if (!f)
+ f = stdout;
+
+ DNS_ANSWER_FOREACH_FULL(rr, ifindex, flags, answer) {
+ const char *t;
+
+ fputc('\t', f);
+
+ t = dns_resource_record_to_string(rr);
+ if (!t) {
+ log_oom();
+ continue;
+ }
+
+ fputs(t, f);
+
+ if (ifindex != 0 || flags != 0)
+ fputs("\t;", f);
+
+ if (ifindex != 0)
+ fprintf(f, " ifindex=%i", ifindex);
+ if (flags & DNS_ANSWER_AUTHENTICATED)
+ fputs(" authenticated", f);
+ if (flags & DNS_ANSWER_CACHEABLE)
+ fputs(" cacheable", f);
+ if (flags & DNS_ANSWER_SHARED_OWNER)
+ fputs(" shared-owner", f);
+ if (flags & DNS_ANSWER_CACHE_FLUSH)
+ fputs(" cache-flush", f);
+ if (flags & DNS_ANSWER_GOODBYE)
+ fputs(" goodbye", f);
+
+ fputc('\n', f);
+ }
+}
+
+int dns_answer_has_dname_for_cname(DnsAnswer *a, DnsResourceRecord *cname) {
+ DnsResourceRecord *rr;
+ int r;
+
+ assert(cname);
+
+ /* Checks whether the answer contains a DNAME record that indicates that the specified CNAME record is
+ * synthesized from it */
+
+ if (cname->key->type != DNS_TYPE_CNAME)
+ return 0;
+
+ DNS_ANSWER_FOREACH(rr, a) {
+ _cleanup_free_ char *n = NULL;
+
+ if (rr->key->type != DNS_TYPE_DNAME)
+ continue;
+ if (rr->key->class != cname->key->class)
+ continue;
+
+ r = dns_name_change_suffix(cname->cname.name, rr->dname.name, dns_resource_key_name(rr->key), &n);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ continue;
+
+ r = dns_name_equal(n, dns_resource_key_name(cname->key));
+ if (r < 0)
+ return r;
+ if (r > 0)
+ return 1;
+ }
+
+ return 0;
+}
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