lib/resolve: avoid possibly unwanted padding

in some SERVFAILs

diff --git a/lib/resolve.c b/lib/resolve.c
index 2d97e900e42e45c3c6e787fbbfb40f51e0490955..f7a0a41c02ca4bc27f760acd7c79ecf6e5666f7b 100644 (file)
--- a/lib/resolve.c
+++ b/lib/resolve.c
@@ -520,12 +520,15 @@ static int write_extra_ranked_records(const ranked_rr_array_t *arr, uint16_t reo
 }
 
 /** @internal Add an EDNS padding RR into the answer if requested and required. */
-static int answer_padding(struct kr_request *request)
+static int answer_padding_maybe(struct kr_request *request)
 {
        if (!request || !request->answer || !request->ctx) {
                assert(false);
                return kr_error(EINVAL);
        }
+       const bool want_pad = request->qsource.flags.tls;
+       if (!want_pad) return kr_ok();
+
        int32_t padding = request->ctx->tls_padding;
        knot_pkt_t *answer = request->answer;
        knot_rrset_t *opt_rr = answer->opt_rr;
@@ -563,7 +566,7 @@ static int answer_fail(struct kr_request *request)
        if (ret == 0 && answer->opt_rr) {
                /* OPT in SERVFAIL response is still useful for cookies/additional info. */
                knot_pkt_begin(answer, KNOT_ADDITIONAL);
-               answer_padding(request); /* Ignore failed padding in SERVFAIL answer. */
+               answer_padding_maybe(request); /* Ignore failed padding in SERVFAIL answer. */
                ret = edns_put(answer, false);
        }
        return ret;
@@ -628,10 +631,8 @@ static int answer_finalize(struct kr_request *request, int state)
        }
        /* Write EDNS information */
        if (answer->opt_rr) {
-               if (request->qsource.flags.tls) {
-                       if (answer_padding(request) != kr_ok()) {
-                               return answer_fail(request);
-                       }
+               if (answer_padding_maybe(request) != kr_ok()) {
+                       return answer_fail(request);
                }
                knot_pkt_begin(answer, KNOT_ADDITIONAL);
                int ret = knot_pkt_put(answer, KNOT_COMPR_HINT_NONE,