tcp: accept rst that fail paws

Change-Id: I945d1644a23b6a3d50c9beaffc732d2b6facd974
Signed-off-by: Florin Coras <fcoras@cisco.com>

diff --git a/src/vnet/tcp/tcp_input.c b/src/vnet/tcp/tcp_input.c
index 94dcaaf..4406d68 100644 (file)
--- a/src/vnet/tcp/tcp_input.c
+++ b/src/vnet/tcp/tcp_input.c
@@ -316,18 +316,18 @@ tcp_segment_validate (tcp_worker_ctx_t * wrk, tcp_connection_t * tc0,
                        tcp_time_now_w_thread (tc0->c_thread_index)))
        {
          tc0->tsval_recent = tc0->rcv_opts.tsval;
-         clib_warning ("paws failed - really old segment. REALLY?");
+         clib_warning ("paws failed: 24-day old segment");
        }
-      else
+      /* Drop after ack if not rst. Resets can fail paws check as per
+       * RFC 7323 sec. 5.2: When an <RST> segment is received, it MUST NOT
+       * be subjected to the PAWS check by verifying an acceptable value in
+       * SEG.TSval */
+      else if (!tcp_rst (th0))
        {
-         /* Drop after ack if not rst */
-         if (!tcp_rst (th0))
-           {
-             tcp_program_ack (wrk, tc0);
-             TCP_EVT_DBG (TCP_EVT_DUPACK_SENT, tc0, vnet_buffer (b0)->tcp);
-           }
+         tcp_program_ack (wrk, tc0);
+         TCP_EVT_DBG (TCP_EVT_DUPACK_SENT, tc0, vnet_buffer (b0)->tcp);
+         goto error;
        }
-      goto error;
     }
 
   /* 1st: check sequence number */