From: Evgeny Vereshchagin <evvers@ya.ru>
Date: Sat, 26 Nov 2022 12:02:46 +0000 (+0000)
Subject: resolve: format zero-length RDATA according to rfc3597
X-Git-Tag: v253-rc1~371^2
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=84f788d6699f289160d7cb3823c1bf9a3826f11f;p=thirdparty%2Fsystemd.git

resolve: format zero-length RDATA according to rfc3597

If the RDATA is of zero length, the text representation contains only
the \# token and the single zero representing the length.
---

diff --git a/src/resolve/resolved-dns-rr.c b/src/resolve/resolved-dns-rr.c
index d47cdbbd8e2..f4fa219ab7c 100644
--- a/src/resolve/resolved-dns-rr.c
+++ b/src/resolve/resolved-dns-rr.c
@@ -1137,12 +1137,15 @@ const char *dns_resource_record_to_string(DnsResourceRecord *rr) {
                 break;
 
         default:
-                t = hexmem(rr->generic.data, rr->generic.data_size);
-                if (!t)
-                        return NULL;
-
                 /* Format as documented in RFC 3597, Section 5 */
-                r = asprintf(&s, "%s \\# %zu %s", k, rr->generic.data_size, t);
+                if (rr->generic.data_size == 0)
+                        r = asprintf(&s, "%s \\# 0", k);
+                else {
+                        t = hexmem(rr->generic.data, rr->generic.data_size);
+                        if (!t)
+                                return NULL;
+                        r = asprintf(&s, "%s \\# %zu %s", k, rr->generic.data_size, t);
+                }
                 if (r < 0)
                         return NULL;
                 break;