nat: TCP state tracking based on RFC 7857/RFC 6146

Implement proper state machine based on above RFCs. ACKs to SYNs/FINs
are no longer required/tracked. This is more friendly to peers and
accounts for lost packets and retransmits.

This change also means that all traffic is translated and forwarded
while in transitory timeout, which helps delivering e.g. retransmitted
FINs, FINACKs and other messages.

Also support reopening a session in transitory timeout after seeing both
FINs by seeing both SYNs again. This helps quick connection
reestablishment if the peers want to.

Type: improvement
Signed-off-by: Klement Sekera <ksekera@cisco.com>
Signed-off-by: Miklos Tirpak <miklos.tirpak@gmail.com>
Change-Id: Ibf521c79463472db97e593bfa02b32b4a06dfd2a

1 files changed, 86 insertions, 80 deletions

diff --git a/src/plugins/nat/nat44-ed/nat44_ed_cli.c b/src/plugins/nat/nat44-ed/nat44_ed_cli.c
index cfd36278674..7693063b8d8 100644
--- a/src/plugins/nat/nat44-ed/nat44_ed_cli.c
+++ b/src/plugins/nat/nat44-ed/nat44_ed_cli.c
@@ -478,16 +478,12 @@ nat44_show_summary_command_fn (vlib_main_t * vm, unformat_input_t * input,
   u64 now = vlib_time_now (vm);
   u64 sess_timeout_time = 0;
 
-  u32 udp_sessions = 0;
-  u32 tcp_sessions = 0;
-  u32 icmp_sessions = 0;
-  u32 other_sessions = 0;
-
-  u32 timed_out = 0;
-  u32 transitory = 0;
-  u32 transitory_wait_closed = 0;
-  u32 transitory_closed = 0;
-  u32 established = 0;
+  struct
+  {
+    u32 total;
+    u32 timed_out;
+  } udp = { 0 }, tcp = { 0 }, tcp_established = { 0 }, tcp_transitory = { 0 },
+    icmp = { 0 }, other = { 0 };
 
   u32 fib;
 
@@ -501,43 +497,44 @@ nat44_show_summary_command_fn (vlib_main_t * vm, unformat_input_t * input,
         {
           pool_foreach (s, tsm->sessions)
            {
-            sess_timeout_time = s->last_heard +
-	      (f64) nat44_session_get_timeout (sm, s);
-            if (now >= sess_timeout_time)
-              timed_out++;
-
-	    switch (s->proto)
-	      {
-	      case IP_PROTOCOL_ICMP:
-		icmp_sessions++;
-		break;
-	      case IP_PROTOCOL_TCP:
-		tcp_sessions++;
-		if (s->state)
-		  {
-		    if (s->tcp_closed_timestamp)
-		      {
-			if (now >= s->tcp_closed_timestamp)
-			  {
-			    ++transitory_closed;
-			  }
-			else
-			  {
-			    ++transitory_wait_closed;
-			  }
-		      }
-		    transitory++;
-		  }
-		else
-		  established++;
-		break;
-	      case IP_PROTOCOL_UDP:
-		udp_sessions++;
-		break;
-	      default:
-		++other_sessions;
-		break;
-	      }
+	     sess_timeout_time =
+	       s->last_heard + (f64) nat44_session_get_timeout (sm, s);
+
+	     switch (s->proto)
+	       {
+	       case IP_PROTOCOL_ICMP:
+		 ++icmp.total;
+		 if (now >= sess_timeout_time)
+		   ++icmp.timed_out;
+		 break;
+	       case IP_PROTOCOL_TCP:
+		 ++tcp.total;
+		 if (now >= sess_timeout_time)
+		   ++tcp.timed_out;
+		 if (nat44_ed_tcp_is_established (s->tcp_state))
+		   {
+		     ++tcp_established.total;
+		     if (now >= sess_timeout_time)
+		       ++tcp_established.timed_out;
+		   }
+		 else
+		   {
+		     ++tcp_transitory.total;
+		     if (now >= sess_timeout_time)
+		       ++tcp_transitory.timed_out;
+		   }
+		 break;
+	       case IP_PROTOCOL_UDP:
+		 ++udp.total;
+		 if (now >= sess_timeout_time)
+		   ++udp.timed_out;
+		 break;
+	       default:
+		 ++other.total;
+		 if (now >= sess_timeout_time)
+		   ++other.timed_out;
+		 break;
+	       }
 	   }
 	  nat44_show_lru_summary (vm, tsm, now, sess_timeout_time);
 	  count += pool_elts (tsm->sessions);
@@ -550,39 +547,40 @@ nat44_show_summary_command_fn (vlib_main_t * vm, unformat_input_t * input,
        {
         sess_timeout_time = s->last_heard +
 	    (f64) nat44_session_get_timeout (sm, s);
-        if (now >= sess_timeout_time)
-          timed_out++;
 
 	switch (s->proto)
 	  {
 	  case IP_PROTOCOL_ICMP:
-	    icmp_sessions++;
+	    ++icmp.total;
+	    if (now >= sess_timeout_time)
+	      ++icmp.timed_out;
 	    break;
 	  case IP_PROTOCOL_TCP:
-	    tcp_sessions++;
-	    if (s->state)
+	    ++tcp.total;
+	    if (now >= sess_timeout_time)
+	      ++tcp.timed_out;
+	    if (nat44_ed_tcp_is_established (s->tcp_state))
 	      {
-		if (s->tcp_closed_timestamp)
-		  {
-		    if (now >= s->tcp_closed_timestamp)
-		      {
-			++transitory_closed;
-		      }
-		    else
-		      {
-			++transitory_wait_closed;
-		      }
-		  }
-		transitory++;
+		++tcp_established.total;
+		if (now >= sess_timeout_time)
+		  ++tcp_established.timed_out;
 	      }
 	    else
-	      established++;
+	      {
+		++tcp_transitory.total;
+		if (now >= sess_timeout_time)
+		  ++tcp_transitory.timed_out;
+	      }
 	    break;
 	  case IP_PROTOCOL_UDP:
-	    udp_sessions++;
+	    ++udp.total;
+	    if (now >= sess_timeout_time)
+	      ++udp.timed_out;
 	    break;
 	  default:
-	    ++other_sessions;
+	    ++other.total;
+	    if (now >= sess_timeout_time)
+	      ++other.timed_out;
 	    break;
 	  }
       }
@@ -590,18 +588,25 @@ nat44_show_summary_command_fn (vlib_main_t * vm, unformat_input_t * input,
       count = pool_elts (tsm->sessions);
     }
 
-  vlib_cli_output (vm, "total timed out sessions: %u", timed_out);
-  vlib_cli_output (vm, "total sessions: %u", count);
-  vlib_cli_output (vm, "total tcp sessions: %u", tcp_sessions);
-  vlib_cli_output (vm, "total tcp established sessions: %u", established);
-  vlib_cli_output (vm, "total tcp transitory sessions: %u", transitory);
-  vlib_cli_output (vm, "total tcp transitory (WAIT-CLOSED) sessions: %u",
-		   transitory_wait_closed);
-  vlib_cli_output (vm, "total tcp transitory (CLOSED) sessions: %u",
-		   transitory_closed);
-  vlib_cli_output (vm, "total udp sessions: %u", udp_sessions);
-  vlib_cli_output (vm, "total icmp sessions: %u", icmp_sessions);
-  vlib_cli_output (vm, "total other sessions: %u", other_sessions);
+  u32 timed_out =
+    tcp.timed_out + icmp.timed_out + udp.timed_out + other.timed_out;
+  vlib_cli_output (vm, "total sessions: %u (timed out: %u)", count, timed_out);
+  vlib_cli_output (vm, "tcp sessions:");
+  vlib_cli_output (vm, "    total: %u (timed out: %u)", tcp.total,
+		   tcp.timed_out);
+  vlib_cli_output (vm, "        established: %u (timed out: %u)",
+		   tcp_established.total, tcp_established.timed_out);
+  vlib_cli_output (vm, "        transitory: %u (timed out: %u)",
+		   tcp_transitory.total, tcp_transitory.timed_out);
+  vlib_cli_output (vm, "udp sessions:");
+  vlib_cli_output (vm, "    total: %u (timed out: %u)", udp.total,
+		   udp.timed_out);
+  vlib_cli_output (vm, "icmp sessions:");
+  vlib_cli_output (vm, "    total: %u (timed out: %u)", icmp.total,
+		   icmp.timed_out);
+  vlib_cli_output (vm, "other sessions:");
+  vlib_cli_output (vm, "    total: %u (timed out: %u)", other.total,
+		   other.timed_out);
   return 0;
 }
 
@@ -1456,7 +1461,8 @@ print:
 		continue;
 	      showed_sessions++;
 	    }
-	  vlib_cli_output (vm, "  %U\n", format_snat_session, tsm, s);
+	  vlib_cli_output (vm, "  %U\n", format_snat_session, sm, tsm, s,
+			   vlib_time_now (vm));
 	}
       if (filtering)
 	{