Ignore data in RST segments, VPP-723

Change-Id: I01650b3b10b79ec549be0d5eceb0e318c06fcb50
Signed-off-by: Florin Coras <fcoras@cisco.com>

2 files changed, 53 insertions, 59 deletions

diff --git a/src/vnet/tcp/tcp_input.c b/src/vnet/tcp/tcp_input.c
index ceb00fc3..82e676d4 100644
--- a/src/vnet/tcp/tcp_input.c
+++ b/src/vnet/tcp/tcp_input.c
@@ -2106,16 +2106,16 @@ tcp46_listen_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 
 	  /* Create child session. For syn-flood protection use filter */
 
-	  /* 1. first check for an RST */
-	  if (tcp_rst (th0))
-	    goto drop;
+	  /* 1. first check for an RST: handled in dispatch */
+	  /* if (tcp_rst (th0))
+	     goto drop; */
 
-	  /* 2. second check for an ACK */
-	  if (tcp_ack (th0))
-	    {
-	      tcp_send_reset (b0, is_ip4);
-	      goto drop;
-	    }
+	  /* 2. second check for an ACK: handled in dispatch */
+	  /* if (tcp_ack (th0))
+	     {
+	     tcp_send_reset (b0, is_ip4);
+	     goto drop;
+	     } */
 
 	  /* 3. check for a SYN (did that already) */
 
@@ -2401,14 +2401,17 @@ tcp46_input_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 	      next0 = tm->dispatch_table[tc0->state][flags0].next;
 	      error0 = tm->dispatch_table[tc0->state][flags0].error;
 
-	      if (PREDICT_FALSE (error0 == TCP_ERROR_DISPATCH))
+	      if (PREDICT_FALSE (error0 == TCP_ERROR_DISPATCH
+				 || next0 == TCP_INPUT_NEXT_RESET))
 		{
-		  tcp_state_t state0 = tc0->state;
 		  /* Overload tcp flags to store state */
+		  tcp_state_t state0 = tc0->state;
 		  vnet_buffer (b0)->tcp.flags = tc0->state;
-		  clib_warning ("disp error state %U flags %U",
-				format_tcp_state, &state0,
-				format_tcp_flags, (int) flags0);
+
+		  if (error0 == TCP_ERROR_DISPATCH)
+		    clib_warning ("disp error state %U flags %U",
+				  format_tcp_state, &state0, format_tcp_flags,
+				  (int) flags0);
 		}
 	    }
 	  else
@@ -2517,6 +2520,8 @@ do {                                                       	\
 
   /* SYNs for new connections -> tcp-listen. */
   _(LISTEN, TCP_FLAG_SYN, TCP_INPUT_NEXT_LISTEN, TCP_ERROR_NONE);
+  _(LISTEN, TCP_FLAG_ACK, TCP_INPUT_NEXT_RESET, TCP_ERROR_NONE);
+  _(LISTEN, TCP_FLAG_RST, TCP_INPUT_NEXT_DROP, TCP_ERROR_NONE);
   /* ACK for for a SYN-ACK -> tcp-rcv-process. */
   _(SYN_RCVD, TCP_FLAG_ACK, TCP_INPUT_NEXT_RCV_PROCESS, TCP_ERROR_NONE);
   _(SYN_RCVD, TCP_FLAG_RST, TCP_INPUT_NEXT_RCV_PROCESS, TCP_ERROR_NONE);
@@ -2534,6 +2539,8 @@ do {                                                       	\
   _(ESTABLISHED, TCP_FLAG_FIN | TCP_FLAG_ACK, TCP_INPUT_NEXT_ESTABLISHED,
     TCP_ERROR_NONE);
   _(ESTABLISHED, TCP_FLAG_RST, TCP_INPUT_NEXT_ESTABLISHED, TCP_ERROR_NONE);
+  _(ESTABLISHED, TCP_FLAG_RST | TCP_FLAG_ACK, TCP_INPUT_NEXT_ESTABLISHED,
+    TCP_ERROR_NONE);
   /* ACK or FIN-ACK to our FIN */
   _(FIN_WAIT_1, TCP_FLAG_ACK, TCP_INPUT_NEXT_RCV_PROCESS, TCP_ERROR_NONE);
   _(FIN_WAIT_1, TCP_FLAG_ACK | TCP_FLAG_FIN, TCP_INPUT_NEXT_RCV_PROCESS,
@@ -2546,7 +2553,8 @@ do {                                                       	\
   _(FIN_WAIT_2, TCP_FLAG_FIN | TCP_FLAG_ACK, TCP_INPUT_NEXT_RCV_PROCESS,
     TCP_ERROR_NONE);
   _(LAST_ACK, TCP_FLAG_ACK, TCP_INPUT_NEXT_RCV_PROCESS, TCP_ERROR_NONE);
-  _(CLOSED, TCP_FLAG_ACK, TCP_INPUT_NEXT_DROP, TCP_ERROR_CONNECTION_CLOSED);
+  _(CLOSED, TCP_FLAG_ACK, TCP_INPUT_NEXT_RESET, TCP_ERROR_CONNECTION_CLOSED);
+  _(CLOSED, TCP_FLAG_RST, TCP_INPUT_NEXT_DROP, TCP_ERROR_CONNECTION_CLOSED);
 #undef _
 }
 
diff --git a/src/vnet/tcp/tcp_output.c b/src/vnet/tcp/tcp_output.c
index 33e599ec..39891fc3 100644
--- a/src/vnet/tcp/tcp_output.c
+++ b/src/vnet/tcp/tcp_output.c
@@ -597,54 +597,41 @@ tcp_enqueue_to_ip_lookup (vlib_main_t * vm, vlib_buffer_t * b, u32 bi,
 
 int
 tcp_make_reset_in_place (vlib_main_t * vm, vlib_buffer_t * b0,
-			 tcp_state_t state, u32 my_thread_index, u8 is_ip4)
+			 tcp_state_t state, u8 thread_index, u8 is_ip4)
 {
-  u8 tcp_hdr_len = sizeof (tcp_header_t);
   ip4_header_t *ih4;
   ip6_header_t *ih6;
   tcp_header_t *th0;
-  ip4_address_t src_ip40;
-  ip6_address_t src_ip60;
-  u16 src_port0;
+  ip4_address_t src_ip40, dst_ip40;
+  ip6_address_t src_ip60, dst_ip60;
+  u16 src_port, dst_port;
   u32 tmp;
+  u32 seq, ack;
+  u8 flags;
 
   /* Find IP and TCP headers */
-  if (is_ip4)
-    {
-      ih4 = vlib_buffer_get_current (b0);
-      th0 = ip4_next_header (ih4);
-    }
-  else
-    {
-      ih6 = vlib_buffer_get_current (b0);
-      th0 = ip6_next_header (ih6);
-    }
+  th0 = tcp_buffer_hdr (b0);
 
-  /* Swap src and dst ip */
+  /* Save src and dst ip */
   if (is_ip4)
     {
+      ih4 = vlib_buffer_get_current (b0);
       ASSERT ((ih4->ip_version_and_header_length & 0xF0) == 0x40);
       src_ip40.as_u32 = ih4->src_address.as_u32;
-      ih4->src_address.as_u32 = ih4->dst_address.as_u32;
-      ih4->dst_address.as_u32 = src_ip40.as_u32;
-
-      /* Chop the end of the pkt */
-      b0->current_length += ip4_header_bytes (ih4) + tcp_hdr_len;
+      dst_ip40.as_u32 = ih4->dst_address.as_u32;
     }
   else
     {
+      ih6 = vlib_buffer_get_current (b0);
       ASSERT ((ih6->ip_version_traffic_class_and_flow_label & 0xF0) == 0x60);
       clib_memcpy (&src_ip60, &ih6->src_address, sizeof (ip6_address_t));
-      clib_memcpy (&ih6->src_address, &ih6->dst_address,
-		   sizeof (ip6_address_t));
-      clib_memcpy (&ih6->dst_address, &src_ip60, sizeof (ip6_address_t));
-
-      /* Chop the end of the pkt */
-      b0->current_length += sizeof (ip6_header_t) + tcp_hdr_len;
+      clib_memcpy (&dst_ip60, &ih6->dst_address, sizeof (ip6_address_t));
     }
 
-  /* Try to determine what/why we're actually resetting and swap
-   * src and dst ports */
+  src_port = th0->src_port;
+  dst_port = th0->dst_port;
+
+  /* Try to determine what/why we're actually resetting */
   if (state == TCP_STATE_CLOSED)
     {
       if (!tcp_syn (th0))
@@ -653,33 +640,32 @@ tcp_make_reset_in_place (vlib_main_t * vm, vlib_buffer_t * b0,
       tmp = clib_net_to_host_u32 (th0->seq_number);
 
       /* Got a SYN for no listener. */
-      th0->flags = TCP_FLAG_RST | TCP_FLAG_ACK;
-      th0->ack_number = clib_host_to_net_u32 (tmp + 1);
-      th0->seq_number = 0;
-
+      flags = TCP_FLAG_RST | TCP_FLAG_ACK;
+      ack = clib_host_to_net_u32 (tmp + 1);
+      seq = 0;
     }
-  else if (state >= TCP_STATE_SYN_SENT)
+  else
     {
-      th0->flags = TCP_FLAG_RST | TCP_FLAG_ACK;
-      th0->seq_number = th0->ack_number;
-      th0->ack_number = 0;
+      flags = TCP_FLAG_RST;
+      seq = th0->ack_number;
+      ack = 0;
     }
 
-  src_port0 = th0->src_port;
-  th0->src_port = th0->dst_port;
-  th0->dst_port = src_port0;
-  th0->window = 0;
-  th0->data_offset_and_reserved = (tcp_hdr_len >> 2) << 4;
-  th0->urgent_pointer = 0;
+  tcp_reuse_buffer (vm, b0);
+  th0 = vlib_buffer_push_tcp_net_order (b0, dst_port, src_port, seq, ack,
+					sizeof (tcp_header_t), flags, 0);
 
-  /* Compute checksum */
   if (is_ip4)
     {
+      ih4 = vlib_buffer_push_ip4 (vm, b0, &dst_ip40, &src_ip40,
+				  IP_PROTOCOL_TCP);
       th0->checksum = ip4_tcp_udp_compute_checksum (vm, b0, ih4);
     }
   else
     {
       int bogus = ~0;
+      ih6 = vlib_buffer_push_ip6 (vm, b0, &dst_ip60, &src_ip60,
+				  IP_PROTOCOL_TCP);
       th0->checksum = ip6_tcp_udp_icmp_compute_checksum (vm, b0, ih6, &bogus);
       ASSERT (!bogus);
     }