From: Lennart Poettering <lennart@poettering.net>
Date: Wed, 13 Mar 2019 18:28:38 +0000 (+0100)
Subject: resolved: don't let EDNS0 OPT dgram size affect TCP
X-Git-Tag: v242-rc1~133^2~1
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=acd74d61d2906a57ec37bfdc793c56b403d18324;p=thirdparty%2Fsystemd.git

resolved: don't let EDNS0 OPT dgram size affect TCP

Fixes: #11884
---

diff --git a/src/resolve/resolved-dns-packet.h b/src/resolve/resolved-dns-packet.h
index 008860b5d1d..56614c4a071 100644
--- a/src/resolve/resolved-dns-packet.h
+++ b/src/resolve/resolved-dns-packet.h
@@ -119,12 +119,12 @@ static inline uint16_t DNS_PACKET_PAYLOAD_SIZE_MAX(DnsPacket *p) {
 
         /* Returns the advertised maximum size for replies, or the DNS default if there's nothing defined. */
 
+        if (p->ipproto == IPPROTO_TCP) /* we ignore EDNS(0) size data on TCP, like everybody else */
+                return DNS_PACKET_SIZE_MAX;
+
         if (p->opt)
                 return MAX(DNS_PACKET_UNICAST_SIZE_MAX, p->opt->key->class);
 
-        if (p->ipproto == IPPROTO_TCP)
-                return DNS_PACKET_SIZE_MAX;
-
         return DNS_PACKET_UNICAST_SIZE_MAX;
 }