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 5f7970129610e3c4708fb227d4111ed0bf2f0d5b..b0c70d0017bf4be0eea58a78c0244c76e3b276b6 100644 (file)
--- 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;