tcp: add option to punt traffic

Until now, if the stack didn't find a connection for a packet, it sent
back a reset. With the punt option enabled, packets are now enqueued to
error-punt where they can be handed off to the host os.

Change-Id: I12dea8694b8bd24c92b0d601412928aa7b8046cb
Signed-off-by: Florin Coras <fcoras@cisco.com>
Signed-off-by: Pierre Pfister <ppfister@cisco.com>

4 files changed, 57 insertions, 6 deletions

diff --git a/src/vnet/tcp/tcp.c b/src/vnet/tcp/tcp.c
index f779428fbaf..f457ef7e536 100644
--- a/src/vnet/tcp/tcp.c
+++ b/src/vnet/tcp/tcp.c
@@ -1398,6 +1398,16 @@ vnet_tcp_enable_disable (vlib_main_t * vm, u8 is_en)
   return 0;
 }
 
+void
+tcp_punt_unknown (vlib_main_t * vm, u8 is_ip4, u8 is_add)
+{
+  tcp_main_t *tm = &tcp_main;
+  if (is_ip4)
+    tm->punt_unknown4 = is_add;
+  else
+    tm->punt_unknown6 = is_add;
+}
+
 clib_error_t *
 tcp_init (vlib_main_t * vm)
 {
@@ -1893,6 +1903,29 @@ VLIB_CLI_COMMAND (tcp_replay_scoreboard_command, static) =
 };
 /* *INDENT-ON* */
 
+static clib_error_t *
+show_tcp_punt_fn (vlib_main_t * vm, unformat_input_t * input,
+		  vlib_cli_command_t * cmd_arg)
+{
+  tcp_main_t *tm = vnet_get_tcp_main ();
+  if (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    return clib_error_return (0, "unknown input `%U'", format_unformat_error,
+			      input);
+  vlib_cli_output (vm, "IPv4 TCP punt: %s",
+		   tm->punt_unknown4 ? "enabled" : "disabled");
+  vlib_cli_output (vm, "IPv6 TCP punt: %s",
+		   tm->punt_unknown6 ? "enabled" : "disabled");
+  return 0;
+}
+/* *INDENT-OFF* */
+VLIB_CLI_COMMAND (show_tcp_punt_command, static) =
+{
+  .path = "show tcp punt",
+  .short_help = "show tcp punt",
+  .function = show_tcp_punt_fn,
+};
+/* *INDENT-ON* */
+
 /*
  * fd.io coding-style-patch-verification: ON
  *
diff --git a/src/vnet/tcp/tcp.h b/src/vnet/tcp/tcp.h
index bb8091af84f..259dbca1519 100644
--- a/src/vnet/tcp/tcp.h
+++ b/src/vnet/tcp/tcp.h
@@ -417,6 +417,9 @@ typedef struct _tcp_main
 
   /** vlib buffer size */
   u32 bytes_per_buffer;
+
+  u8 punt_unknown4;
+  u8 punt_unknown6;
 } tcp_main_t;
 
 extern tcp_main_t tcp_main;
@@ -441,6 +444,8 @@ tcp_buffer_hdr (vlib_buffer_t * b)
 
 clib_error_t *vnet_tcp_enable_disable (vlib_main_t * vm, u8 is_en);
 
+void tcp_punt_unknown (vlib_main_t * vm, u8 is_ip4, u8 is_add);
+
 always_inline tcp_connection_t *
 tcp_connection_get (u32 conn_index, u32 thread_index)
 {
diff --git a/src/vnet/tcp/tcp_error.def b/src/vnet/tcp/tcp_error.def
index 08922315c99..a179717ff13 100644
--- a/src/vnet/tcp/tcp_error.def
+++ b/src/vnet/tcp/tcp_error.def
@@ -39,4 +39,5 @@ tcp_error (RST_SENT, "Resets sent")
 tcp_error (INVALID_CONNECTION, "Invalid connection")
 tcp_error (NO_WND, "No window")
 tcp_error (CONNECTION_CLOSED, "Connection closed")
-tcp_error (CREATE_EXISTS, "Connection already exists")
\ No newline at end of file
+tcp_error (CREATE_EXISTS, "Connection already exists")
+tcp_error (PUNT, "Packets punted")
\ No newline at end of file
diff --git a/src/vnet/tcp/tcp_input.c b/src/vnet/tcp/tcp_input.c
index 64a07070ec2..bd57eca3223 100644
--- a/src/vnet/tcp/tcp_input.c
+++ b/src/vnet/tcp/tcp_input.c
@@ -2869,6 +2869,7 @@ typedef enum _tcp_input_next
   TCP_INPUT_NEXT_SYN_SENT,
   TCP_INPUT_NEXT_ESTABLISHED,
   TCP_INPUT_NEXT_RESET,
+  TCP_INPUT_NEXT_PUNT,
   TCP_INPUT_N_NEXT
 } tcp_input_next_t;
 
@@ -2878,7 +2879,8 @@ typedef enum _tcp_input_next
   _ (RCV_PROCESS, "tcp4-rcv-process")           \
   _ (SYN_SENT, "tcp4-syn-sent")                 \
   _ (ESTABLISHED, "tcp4-established")		\
-  _ (RESET, "tcp4-reset")
+  _ (RESET, "tcp4-reset")			\
+  _ (PUNT, "error-punt")
 
 #define foreach_tcp6_input_next                 \
   _ (DROP, "error-drop")                        \
@@ -2886,7 +2888,8 @@ typedef enum _tcp_input_next
   _ (RCV_PROCESS, "tcp6-rcv-process")           \
   _ (SYN_SENT, "tcp6-syn-sent")                 \
   _ (ESTABLISHED, "tcp6-established")		\
-  _ (RESET, "tcp6-reset")
+  _ (RESET, "tcp6-reset")			\
+  _ (PUNT, "error-punt")
 
 #define filter_flags (TCP_FLAG_SYN|TCP_FLAG_ACK|TCP_FLAG_RST|TCP_FLAG_FIN)
 
@@ -3010,9 +3013,18 @@ tcp46_input_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 	    }
 	  else
 	    {
-	      /* Send reset */
-	      next0 = TCP_INPUT_NEXT_RESET;
-	      error0 = TCP_ERROR_NO_LISTENER;
+	      if ((is_ip4 && tm->punt_unknown4) ||
+		  (!is_ip4 && tm->punt_unknown6))
+		{
+		  next0 = TCP_INPUT_NEXT_PUNT;
+		  error0 = TCP_ERROR_PUNT;
+		}
+	      else
+		{
+		  /* Send reset */
+		  next0 = TCP_INPUT_NEXT_RESET;
+		  error0 = TCP_ERROR_NO_LISTENER;
+		}
 	    }
 
 	done: