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-rw-r--r--src/resolve/resolved-dns-question.c552
1 files changed, 552 insertions, 0 deletions
diff --git a/src/resolve/resolved-dns-question.c b/src/resolve/resolved-dns-question.c
new file mode 100644
index 0000000..5754c85
--- /dev/null
+++ b/src/resolve/resolved-dns-question.c
@@ -0,0 +1,552 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "alloc-util.h"
+#include "dns-domain.h"
+#include "dns-type.h"
+#include "resolved-dns-question.h"
+#include "socket-util.h"
+
+DnsQuestion *dns_question_new(size_t n) {
+ DnsQuestion *q;
+
+ if (n > UINT16_MAX) /* We can only place 64K key in an question section at max */
+ n = UINT16_MAX;
+
+ q = malloc0(offsetof(DnsQuestion, items) + sizeof(DnsQuestionItem) * n);
+ if (!q)
+ return NULL;
+
+ q->n_ref = 1;
+ q->n_allocated = n;
+
+ return q;
+}
+
+static DnsQuestion *dns_question_free(DnsQuestion *q) {
+ DnsResourceKey *key;
+
+ assert(q);
+
+ DNS_QUESTION_FOREACH(key, q)
+ dns_resource_key_unref(key);
+
+ return mfree(q);
+}
+
+DEFINE_TRIVIAL_REF_UNREF_FUNC(DnsQuestion, dns_question, dns_question_free);
+
+int dns_question_add_raw(DnsQuestion *q, DnsResourceKey *key, DnsQuestionFlags flags) {
+ /* Insert without checking for duplicates. */
+
+ assert(key);
+ assert(q);
+
+ if (q->n_keys >= q->n_allocated)
+ return -ENOSPC;
+
+ q->items[q->n_keys++] = (DnsQuestionItem) {
+ .key = dns_resource_key_ref(key),
+ .flags = flags,
+ };
+ return 0;
+}
+
+static int dns_question_add_raw_all(DnsQuestion *a, DnsQuestion *b) {
+ DnsQuestionItem *item;
+ int r;
+
+ DNS_QUESTION_FOREACH_ITEM(item, b) {
+ r = dns_question_add_raw(a, item->key, item->flags);
+ if (r < 0)
+ return r;
+ }
+
+ return 0;
+}
+
+int dns_question_add(DnsQuestion *q, DnsResourceKey *key, DnsQuestionFlags flags) {
+ DnsQuestionItem *item;
+ int r;
+
+ assert(key);
+
+ if (!q)
+ return -ENOSPC;
+
+
+ DNS_QUESTION_FOREACH_ITEM(item, q) {
+ r = dns_resource_key_equal(item->key, key);
+ if (r < 0)
+ return r;
+ if (r > 0 && item->flags == flags)
+ return 0;
+ }
+
+ return dns_question_add_raw(q, key, flags);
+}
+
+static int dns_question_add_all(DnsQuestion *a, DnsQuestion *b) {
+ DnsQuestionItem *item;
+ int r;
+
+ DNS_QUESTION_FOREACH_ITEM(item, b) {
+ r = dns_question_add(a, item->key, item->flags);
+ if (r < 0)
+ return r;
+ }
+
+ return 0;
+}
+
+int dns_question_matches_rr(DnsQuestion *q, DnsResourceRecord *rr, const char *search_domain) {
+ DnsResourceKey *key;
+ int r;
+
+ assert(rr);
+
+ if (!q)
+ return 0;
+
+ DNS_QUESTION_FOREACH(key, q) {
+ r = dns_resource_key_match_rr(key, rr, search_domain);
+ if (r != 0)
+ return r;
+ }
+
+ return 0;
+}
+
+int dns_question_matches_cname_or_dname(DnsQuestion *q, DnsResourceRecord *rr, const char *search_domain) {
+ DnsResourceKey *key;
+ int r;
+
+ assert(rr);
+
+ if (!q)
+ return 0;
+
+ if (!IN_SET(rr->key->type, DNS_TYPE_CNAME, DNS_TYPE_DNAME))
+ return 0;
+
+ DNS_QUESTION_FOREACH(key, q) {
+ /* 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;
+
+ r = dns_resource_key_match_cname_or_dname(key, rr->key, search_domain);
+ if (r != 0)
+ return r;
+ }
+
+ return 0;
+}
+
+int dns_question_is_valid_for_query(DnsQuestion *q) {
+ const char *name;
+ size_t 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->items[0].key);
+ 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->items[i].key);
+
+ if (i > 0) {
+ r = dns_name_equal(dns_resource_key_name(q->items[i].key), name);
+ if (r <= 0)
+ return r;
+ }
+
+ if (!dns_type_is_valid_query(q->items[i].key->type))
+ return 0;
+ }
+
+ return 1;
+}
+
+int dns_question_contains_key(DnsQuestion *q, const DnsResourceKey *k) {
+ size_t j;
+ int r;
+
+ assert(k);
+
+ if (!q)
+ return 0;
+
+
+ for (j = 0; j < q->n_keys; j++) {
+ r = dns_resource_key_equal(q->items[j].key, k);
+ if (r != 0)
+ return r;
+ }
+
+ return 0;
+}
+
+static int dns_question_contains_item(DnsQuestion *q, const DnsQuestionItem *i) {
+ DnsQuestionItem *item;
+ int r;
+
+ assert(i);
+
+ DNS_QUESTION_FOREACH_ITEM(item, q) {
+ if (item->flags != i->flags)
+ continue;
+ r = dns_resource_key_equal(item->key, i->key);
+ if (r != 0)
+ return r;
+ }
+
+ return false;
+}
+
+int dns_question_is_equal(DnsQuestion *a, DnsQuestion *b) {
+ DnsQuestionItem *item;
+ 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 items in a are also contained b, and vice versa */
+
+ DNS_QUESTION_FOREACH_ITEM(item, a) {
+ r = dns_question_contains_item(b, item);
+ if (r <= 0)
+ return r;
+ }
+ DNS_QUESTION_FOREACH_ITEM(item, b) {
+ r = dns_question_contains_item(a, item);
+ 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, 0);
+ if (r < 0)
+ return r;
+ }
+
+ *ret = TAKE_PTR(n);
+
+ 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->items[0].key);
+}
+
+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 IPv6 is off and the request has an unspecified lookup family, restrict it automatically to
+ * IPv4. */
+ if (family == AF_UNSPEC && !socket_ipv6_is_enabled())
+ family = AF_INET;
+
+ if (convert_idna) {
+ r = dns_name_apply_idna(name, &buf);
+ if (r < 0)
+ return r;
+ if (r > 0 && !streq(name, buf))
+ name = buf;
+ else
+ /* We did not manage to create convert the idna name, or it's
+ * the same as the original name. We assume the caller already
+ * created an unconverted question, so let's not repeat work
+ * unnecessarily. */
+ return -EALREADY;
+ }
+
+ 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, 0);
+ 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, 0);
+ if (r < 0)
+ return r;
+ }
+
+ *ret = TAKE_PTR(q);
+
+ 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, 0);
+ if (r < 0)
+ return r;
+
+ *ret = TAKE_PTR(q);
+
+ 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;
+ if (r > 0)
+ 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, 0);
+ 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, 0);
+ if (r < 0)
+ return r;
+ }
+
+ *ret = TAKE_PTR(q);
+
+ return 0;
+}
+
+/*
+ * This function is not used in the code base, but is useful when debugging. Do not delete.
+ */
+void dns_question_dump(DnsQuestion *question, FILE *f) {
+ DnsResourceKey *k;
+
+ if (!f)
+ f = stdout;
+
+ DNS_QUESTION_FOREACH(k, question) {
+ char buf[DNS_RESOURCE_KEY_STRING_MAX];
+
+ fputc('\t', f);
+ fputs(dns_resource_key_to_string(k, buf, sizeof(buf)), f);
+ fputc('\n', f);
+ }
+}
+
+int dns_question_merge(DnsQuestion *a, DnsQuestion *b, DnsQuestion **ret) {
+ _cleanup_(dns_question_unrefp) DnsQuestion *k = NULL;
+ int r;
+
+ assert(ret);
+
+ if (a == b || dns_question_size(b) <= 0) {
+ *ret = dns_question_ref(a);
+ return 0;
+ }
+
+ if (dns_question_size(a) <= 0) {
+ *ret = dns_question_ref(b);
+ return 0;
+ }
+
+ k = dns_question_new(dns_question_size(a) + dns_question_size(b));
+ if (!k)
+ return -ENOMEM;
+
+ r = dns_question_add_raw_all(k, a);
+ if (r < 0)
+ return r;
+
+ r = dns_question_add_all(k, b);
+ if (r < 0)
+ return r;
+
+ *ret = TAKE_PTR(k);
+ return 0;
+}
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