dhcp6: fix wrong length for IA_PD dhcp6 option

yuwata · poettering · commit fa92d38428cd · 2021-03-16T21:29:49.000+01:00
Fixes an issue introduced by 73b49d4. When PrefixDelegationHint= is not set, dhcp6_option_append_pd() sets wrong length for IA_PD option, as `r` is `-EINVAL`. Fixes systemd#19021.
diff --git a/src/libsystemd-network/dhcp6-option.c b/src/libsystemd-network/dhcp6-option.c
@@ -257,9 +257,9 @@ int dhcp6_option_append_pd(uint8_t **buf, size_t *buflen, const DHCP6IA *pd, con
                 len += r;
         }
 
-        if (hint_pd_prefix) {
+        if (hint_pd_prefix && hint_pd_prefix->iapdprefix.prefixlen > 0) {
                 r = option_append_pd_prefix(buf, buflen, hint_pd_prefix);
-                if (r < 0 && r != -EINVAL)
+                if (r < 0)
                         return r;
 
                 len += r;
