From: Lennart Poettering <lennart@poettering.net>
Date: Tue, 29 Dec 2015 18:00:53 +0000 (+0100)
Subject: resolved: reset RR TTL to 0, if MSB is set
X-Git-Tag: v229~180^2~9
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=0d0b52d79c2e9a79aeff9a9cca877de8b4fcbd16;p=thirdparty%2Fsystemd.git

resolved: reset RR TTL to 0, if MSB is set

RFC 2181, Section 8 suggests to treat an RR TTL with the MSB set as 0.
Implement this.
---

diff --git a/src/resolve/resolved-dns-packet.c b/src/resolve/resolved-dns-packet.c
index 5f797012961..b0c70d0017b 100644
--- a/src/resolve/resolved-dns-packet.c
+++ b/src/resolve/resolved-dns-packet.c
@@ -1580,6 +1580,11 @@ int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, bool *ret_cache_fl
         if (r < 0)
                 goto fail;
 
+        /* RFC 2181, Section 8, suggests to
+         * treat a TTL with the MSB set as a zero TTL. */
+        if (rr->ttl & UINT32_C(0x80000000))
+                rr->ttl = 0;
+
         r = dns_packet_read_uint16(p, &rdlength, NULL);
         if (r < 0)
                 goto fail;