Empty DNS reply with OK status is another way to say NODATA.

Sometimes DNS reply has nothing but query section. It does not look like
error, so it should be treated as NODATA with TTL=0 as soon as there is
no SOA record to deduce negative TTL from.

diff --git a/evdns.c b/evdns.c
index 1550fe8f163608f43125cc9b8bb44ae9f594b0e2..7ad42b74cf95d7d6416d25ed7432e5cee59c0d88 100644 (file)
--- a/evdns.c
+++ b/evdns.c
@@ -1044,7 +1044,7 @@ reply_parse(struct evdns_base *base, u8 *packet, int length) {
                 */
                TEST_NAME;
                j += 4;
-               if (j >= length) goto err;
+               if (j > length) goto err;
        }
 
        if (!name_matches)

diff --git a/test/regress_dns.c b/test/regress_dns.c
index 3eea482817829d3eaaa0c03992fae715dca1e6dc..33cf9a9776bf627791d3ea2aa5c5936d4f26b818 100644 (file)
--- a/test/regress_dns.c
+++ b/test/regress_dns.c
@@ -497,6 +497,7 @@ static struct regress_dns_server_table search_table[] = {
        { "host2.c.example.com", "err", "3", 0 },
        { "hostn.a.example.com", "errsoa", "0", 0 },
        { "hostn.b.example.com", "errsoa", "3", 0 },
+       { "hostn.c.example.com", "err", "0", 0 },
 
        { "host", "err", "3", 0 },
        { "host2", "err", "3", 0 },
@@ -513,7 +514,7 @@ dns_search_test(void *arg)
        ev_uint16_t portnum = 0;
        char buf[64];
 
-       struct generic_dns_callback_result r[7];
+       struct generic_dns_callback_result r[8];
 
        tt_assert(regress_dnsserver(base, &portnum, search_table));
        evutil_snprintf(buf, sizeof(buf), "127.0.0.1:%d", (int)portnum);
@@ -535,6 +536,7 @@ dns_search_test(void *arg)
        evdns_base_resolve_ipv4(dns, "host3", 0, generic_dns_callback, &r[4]);
        evdns_base_resolve_ipv4(dns, "hostn.a.example.com", DNS_NO_SEARCH, generic_dns_callback, &r[5]);
        evdns_base_resolve_ipv4(dns, "hostn.b.example.com", DNS_NO_SEARCH, generic_dns_callback, &r[6]);
+       evdns_base_resolve_ipv4(dns, "hostn.c.example.com", DNS_NO_SEARCH, generic_dns_callback, &r[7]);
 
        event_base_dispatch(base);
 
@@ -551,6 +553,8 @@ dns_search_test(void *arg)
        tt_int_op(r[5].ttl, ==, 42);
        tt_int_op(r[6].result, ==, DNS_ERR_NOTEXIST);
        tt_int_op(r[6].ttl, ==, 42);
+       tt_int_op(r[7].result, ==, DNS_ERR_NODATA);
+       tt_int_op(r[7].ttl, ==, 0);
 
 end:
        if (dns)