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-rw-r--r--src/resolve/resolved-dns-query.c166
-rw-r--r--src/resolve/resolved-dns-scope.c8
2 files changed, 169 insertions, 5 deletions
diff --git a/src/resolve/resolved-dns-query.c b/src/resolve/resolved-dns-query.c
index 418d9721ef..3ada442006 100644
--- a/src/resolve/resolved-dns-query.c
+++ b/src/resolve/resolved-dns-query.c
@@ -19,6 +19,8 @@
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
+#include "hostname-util.h"
+#include "dns-domain.h"
#include "resolved-dns-query.h"
@@ -212,6 +214,156 @@ static int dns_query_add_transaction_split(DnsQuery *q, DnsScope *s) {
return 0;
}
+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, 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 void dns_query_synthesize_reply(DnsQuery *q, DnsTransactionState *state) {
+ _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
+ unsigned i;
+ int r;
+
+ assert(q);
+ assert(state);
+
+ /* Tries to synthesize localhost RR replies where appropriate */
+
+ if (!IN_SET(*state,
+ DNS_TRANSACTION_FAILURE,
+ DNS_TRANSACTION_NO_SERVERS,
+ DNS_TRANSACTION_TIMEOUT,
+ DNS_TRANSACTION_ATTEMPTS_MAX_REACHED))
+ return;
+
+ for (i = 0; i < q->question->n_keys; i++) {
+ _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
+ const char *name;
+
+ if (q->question->keys[i]->class != DNS_CLASS_IN &&
+ q->question->keys[i]->class != DNS_CLASS_ANY)
+ continue;
+
+ name = DNS_RESOURCE_KEY_NAME(q->question->keys[i]);
+
+ if (is_localhost(name)) {
+
+ switch (q->question->keys[i]->type) {
+
+ case DNS_TYPE_A:
+ case DNS_TYPE_ANY:
+ rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_A, name);
+ if (!rr) {
+ log_oom();
+ return;
+ }
+
+ rr->a.in_addr.s_addr = htobe32(INADDR_LOOPBACK);
+ break;
+
+ case DNS_TYPE_AAAA:
+ rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_AAAA, name);
+ if (!rr) {
+ log_oom();
+ return;
+ }
+
+ rr->aaaa.in6_addr = in6addr_loopback;
+ break;
+ }
+
+ } else if (IN_SET(q->question->keys[i]->type, DNS_TYPE_PTR, DNS_TYPE_ANY) &&
+ (dns_name_endswith(name, "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)) {
+
+ rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_PTR, name);
+ if (!rr) {
+ log_oom();
+ return;
+ }
+
+ rr->ptr.name = strdup("localhost");
+ if (!rr->ptr.name) {
+ log_oom();
+ return;
+ }
+ }
+
+ if (!rr)
+ continue;
+
+ if (!answer) {
+ answer = dns_answer_new(q->question->n_keys);
+ if (!answer) {
+ log_oom();
+ return;
+ }
+ }
+
+ r = dns_answer_add(answer, rr);
+ if (r < 0) {
+ log_error_errno(r, "Failed to add synthetic RR to answer: %m");
+ return;
+ }
+ }
+
+ if (!answer)
+ return;
+
+ dns_answer_unref(q->answer);
+ q->answer = answer;
+ answer = NULL;
+
+ q->answer_ifindex = SYNTHESIZE_IFINDEX(q->ifindex);
+ q->answer_family = SYNTHESIZE_FAMILY(q->flags);
+ q->answer_protocol = SYNTHESIZE_PROTOCOL(q->flags);
+ q->answer_rcode = DNS_RCODE_SUCCESS;
+
+ *state = DNS_TRANSACTION_SUCCESS;
+}
+
int dns_query_go(DnsQuery *q) {
DnsScopeMatch found = DNS_SCOPE_NO;
DnsScope *s, *first = NULL;
@@ -253,8 +405,17 @@ int dns_query_go(DnsQuery *q) {
}
}
- if (found == DNS_SCOPE_NO)
+ if (found == DNS_SCOPE_NO) {
+ DnsTransactionState state = DNS_TRANSACTION_NO_SERVERS;
+
+ dns_query_synthesize_reply(q, &state);
+ if (state != DNS_TRANSACTION_NO_SERVERS) {
+ dns_query_complete(q, state);
+ return 1;
+ }
+
return -ESRCH;
+ }
r = dns_query_add_transaction_split(q, first);
if (r < 0)
@@ -428,6 +589,9 @@ void dns_query_ready(DnsQuery *q) {
q->answer_family = scope ? scope->family : AF_UNSPEC;
}
+ /* Try to synthesize a reply if we couldn't resolve something. */
+ dns_query_synthesize_reply(q, &state);
+
dns_query_complete(q, state);
}
diff --git a/src/resolve/resolved-dns-scope.c b/src/resolve/resolved-dns-scope.c
index b8414da87e..57d9071dfc 100644
--- a/src/resolve/resolved-dns-scope.c
+++ b/src/resolve/resolved-dns-scope.c
@@ -325,10 +325,6 @@ DnsScopeMatch dns_scope_good_domain(DnsScope *s, int ifindex, uint64_t flags, co
if ((SD_RESOLVED_FLAGS_MAKE(s->protocol, s->family) & flags) == 0)
return DNS_SCOPE_NO;
- STRV_FOREACH(i, s->domains)
- if (dns_name_endswith(domain, *i) > 0)
- return DNS_SCOPE_YES;
-
if (dns_name_root(domain) != 0)
return DNS_SCOPE_NO;
@@ -340,6 +336,10 @@ DnsScopeMatch dns_scope_good_domain(DnsScope *s, int ifindex, uint64_t flags, co
dns_name_equal(domain, "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)
return DNS_SCOPE_NO;
+ STRV_FOREACH(i, s->domains)
+ if (dns_name_endswith(domain, *i) > 0)
+ return DNS_SCOPE_YES;
+
if (s->protocol == DNS_PROTOCOL_DNS) {
if (dns_name_endswith(domain, "254.169.in-addr.arpa") == 0 &&
dns_name_endswith(domain, "0.8.e.f.ip6.arpa") == 0 &&
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-12-22 18:24:21 +0000