COLO-compare: Optimize tcp compare for option field

In this patch we support packet that have tcp options field.
Add tcp options field check, If the packet have options
field we just skip it and compare tcp payload,
Avoid unnecessary checkpoint, optimize performance.

Signed-off-by: Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

diff --git a/net/colo-compare.c b/net/colo-compare.c
index 9b09cfc9c09749e6ed4b0fa3c6e259a98a517547..4ab80b1cbbafa0ec0433f973d3df57f40d7a13c7 100644 (file)
--- a/net/colo-compare.c
+++ b/net/colo-compare.c
@@ -233,7 +233,32 @@ static int colo_packet_compare_tcp(Packet *spkt, Packet *ppkt)
         spkt->ip->ip_sum = ppkt->ip->ip_sum;
     }
 
-    if (ptcp->th_sum == stcp->th_sum) {
+    /*
+     * Check tcp header length for tcp option field.
+     * th_off > 5 means this tcp packet have options field.
+     * The tcp options maybe always different.
+     * for example:
+     * From RFC 7323.
+     * TCP Timestamps option (TSopt):
+     * Kind: 8
+     *
+     * Length: 10 bytes
+     *
+     *    +-------+-------+---------------------+---------------------+
+     *    |Kind=8 |  10   |   TS Value (TSval)  |TS Echo Reply (TSecr)|
+     *    +-------+-------+---------------------+---------------------+
+     *       1       1              4                     4
+     *
+     * In this case the primary guest's timestamp always different with
+     * the secondary guest's timestamp. COLO just focus on payload,
+     * so we just need skip this field.
+     */
+    if (ptcp->th_off > 5) {
+        ptrdiff_t tcp_offset;
+        tcp_offset = ppkt->transport_header - (uint8_t *)ppkt->data
+                     + (ptcp->th_off * 4);
+        res = colo_packet_compare_common(ppkt, spkt, tcp_offset);
+    } else if (ptcp->th_sum == stcp->th_sum) {
         res = colo_packet_compare_common(ppkt, spkt, ETH_HLEN);
     } else {
         res = -1;