Improve asr error handling.

When an upstream nameserver is not available asr is not synthesizing a
SERVFAIL rcode (duh), but sets ar_errno. When we need SERVFAIL further
down,we need to set the rcode ourselves.

While here, don't complain about a too short packet when asr already
told us that resolving did not work out in check_dns64_done.

OK semarie

diff --git a/sbin/unwind/resolver.c b/sbin/unwind/resolver.c
index 7161423..0682e9e 100644 (file)
--- a/sbin/unwind/resolver.c
+++ b/sbin/unwind/resolver.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: resolver.c,v 1.158 2023/02/08 08:01:25 tb Exp $       */
+/*     $OpenBSD: resolver.c,v 1.159 2023/04/18 09:57:08 florian Exp $  */
 
 
 /*
@@ -1623,8 +1623,9 @@ void
 asr_resolve_done(struct asr_result *ar, void *arg)
 {
        struct resolver_cb_data *cb_data = arg;
-       cb_data->cb(cb_data->res, cb_data->data, ar->ar_rcode, ar->ar_data,
-           ar->ar_datalen, 0, NULL);
+       cb_data->cb(cb_data->res, cb_data->data, ar->ar_errno == 0 ?
+           ar->ar_rcode : LDNS_RCODE_SERVFAIL, ar->ar_data, ar->ar_datalen, 0,
+           NULL);
        free(ar->ar_data);
        resolver_unref(cb_data->res);
        free(cb_data);
@@ -2289,6 +2290,9 @@ check_dns64_done(struct asr_result *ar, void *arg)
        int                              preflen, count = 0;
        void                            *asr_ctx = arg;
 
+       if (ar->ar_errno != 0)
+               goto fail;
+
        memset(&qinfo, 0, sizeof(qinfo));
        alloc_init(&alloc, NULL, 0);
 
@@ -2390,6 +2394,7 @@ check_dns64_done(struct asr_result *ar, void *arg)
        alloc_clear(&alloc);
        regional_destroy(region);
        sldns_buffer_free(buf);
+ fail:
        free(ar->ar_data);
        asr_resolver_free(asr_ctx);
 }