On Mon, Apr 03, 2017 at 04:10:15PM +0530, [email protected] wrote:
> From: Numan Siddique <[email protected]>
>
> This patch adds a new OVN action 'dns_lookup' to support native DNS.
> ovn-controller parses this action and adds a NXT_PACKET_IN2
> OF flow with 'pause' flag set.
>
> A new table 'DNS' is added in the SB DB to look up and resolve
> the DNS queries. When a valid DNS packet is received by
> ovn-controller, it looks up the DNS name in the 'DNS' table
> and if successful, it frames a DNS reply, resumes the packet
> and stores 1 in the 1-bit subfield. If the packet is invalid
> or cannot be resolved, it resumes the packet without any
> modifications and stores 0 in the 1-bit subfield.
>
> reg0[4] = dns_lookup(); next;
>
> An upcoming patch will use this action and adds logical flows.
>
> Signed-off-by: Numan Siddique <[email protected]>
Thanks for revising this! DNS is important and it goes one step closer
to offering everything that OpenStack needs from OVN.
I think that Guru is planning to review this too, particularly regarding
the database schema (and its documentation, I hope), but I'll offer some
preliminary comments of my own.
I tend to think that the DNS protocol declarations should go in
lib/packets.h, where OVS generally keeps protocol declarations, instead
of ovn/lib/ovn-util.h.
I think that the ovn-trace implementation of dns_lookup should at least
set the destination bit to 0, to indicate that the lookup failed.
I suggest folding in the following incremental to make the code easier
to read. (I haven't tested it.)
Thanks,
Ben.
--8<--------------------------cut here-------------------------->8--
diff --git a/ovn/controller/pinctrl.c b/ovn/controller/pinctrl.c
index 9c669c96884a..e349817e7f4c 100644
--- a/ovn/controller/pinctrl.c
+++ b/ovn/controller/pinctrl.c
@@ -662,6 +662,18 @@ exit:
}
static void
+put_be16(struct ofpbuf *buf, ovs_be16 x)
+{
+ ofpbuf_put(buf, &x, sizeof x);
+}
+
+static void
+put_be32(struct ofpbuf *buf, ovs_be32 x)
+{
+ ofpbuf_put(buf, &x, sizeof x);
+}
+
+static void
pinctrl_handle_dns_lookup(
struct dp_packet *pkt_in, struct ofputil_packet_in *pin,
struct ofpbuf *userdata, struct ofpbuf *continuation,
@@ -722,27 +734,19 @@ pinctrl_handle_dns_lookup(
/* Extract the hostname. If the hostname is - 'www.ovn.org' it would be
* encoded as (in hex) - 03 77 77 77 03 6f 76 63 03 6f 72 67 00.
*/
- bool hostname_present = true;
while ((in_dns_data + idx) < end && in_dns_data[idx]) {
uint8_t label_len = in_dns_data[idx++];
if (in_dns_data + idx + label_len > end) {
- hostname_present = false;
- break;
- }
- for (uint8_t i = 0; i < label_len; i++) {
- ds_put_char(&hostname, in_dns_data[idx++]);
+ ds_destroy(&hostname);
+ goto exit;
}
+ ds_put_buffer(&hostname, (const char *) in_dns_data + idx, label_len);
+ idx += label_len;
ds_put_char(&hostname, '.');
}
- if (!hostname_present) {
- ds_destroy(&hostname);
- goto exit;
- }
-
idx++;
ds_chomp(&hostname, '.');
- ds_put_char(&hostname, 0);
in_dns_data += idx;
/* Query should have TYPE and CLASS fields */
@@ -809,35 +813,25 @@ pinctrl_handle_dns_lookup(
* be IP address of the domain name.
*/
ofpbuf_put(&dns_answer, in_hostname, idx);
- ovs_be16 v = htons(DNS_QUERY_TYPE_A);
- ofpbuf_put(&dns_answer, &v, sizeof(ovs_be16));
- v = htons(DNS_CLASS_IN);
- ofpbuf_put(&dns_answer, &v, sizeof(ovs_be16));
- ovs_be32 ttl = htonl(DNS_DEFAULT_RR_TTL);
- ofpbuf_put(&dns_answer, &ttl, sizeof(ovs_be32));
- v = htons(sizeof(ovs_be32)); /* Length of the RDATA field */
- ofpbuf_put(&dns_answer, &v, sizeof(ovs_be16));
- ofpbuf_put(&dns_answer, &ip_addrs.ipv4_addrs[i].addr,
- sizeof(ovs_be32));
+ put_be16(&dns_answer, htons(DNS_QUERY_TYPE_A));
+ put_be16(&dns_answer, htons(DNS_CLASS_IN));
+ put_be32(&dns_answer, htonl(DNS_DEFAULT_RR_TTL));
+ put_be16(&dns_answer, htons(sizeof(ovs_be32)));
+ put_be32(&dns_answer, ip_addrs.ipv4_addrs[i].addr);
ancount++;
}
}
if (query_type == DNS_QUERY_TYPE_AAAA ||
- query_type == DNS_QUERY_TYPE_ANY) {
+ query_type == DNS_QUERY_TYPE_ANY) {
for (size_t i = 0; i < ip_addrs.n_ipv6_addrs; i++) {
ofpbuf_put(&dns_answer, in_hostname, idx);
- ovs_be16 v = htons(DNS_QUERY_TYPE_AAAA);
- ofpbuf_put(&dns_answer, &v, sizeof(ovs_be16));
- v = htons(DNS_CLASS_IN);
- ofpbuf_put(&dns_answer, &v, sizeof(ovs_be16));
- ovs_be32 ttl = htonl(DNS_DEFAULT_RR_TTL);
- ofpbuf_put(&dns_answer, &ttl, sizeof(ovs_be32));
- /* Length of the RDATA field */
- v = htons(sizeof(ip_addrs.ipv6_addrs[i].addr.s6_addr));
- ofpbuf_put(&dns_answer, &v, sizeof(ovs_be16));
- ofpbuf_put(&dns_answer, &ip_addrs.ipv6_addrs[i].addr.s6_addr,
- sizeof(ip_addrs.ipv6_addrs[i].addr.s6_addr));
+ put_be16(&dns_answer, htons(DNS_QUERY_TYPE_AAAA));
+ put_be16(&dns_answer, htons(DNS_CLASS_IN));
+ put_be32(&dns_answer, htonl(DNS_DEFAULT_RR_TTL));
+ const struct in6_addr *ip6 = &ip_addrs.ipv6_addrs[i].addr;
+ put_be16(&dns_answer, htons(sizeof *ip6));
+ ofpbuf_put(&dns_answer, ip6, sizeof *ip6);
ancount++;
}
}
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