BFD: loop back echo packets

Change-Id: I772b63ac25ebfccaff9ab9d8d0b1445e85f21df7
Signed-off-by: Klement Sekera <ksekera@cisco.com>

1 files changed, 218 insertions, 11 deletions

diff --git a/src/vnet/bfd/bfd_udp.c b/src/vnet/bfd/bfd_udp.c
index 75b35974..8519009d 100644
--- a/src/vnet/bfd/bfd_udp.c
+++ b/src/vnet/bfd/bfd_udp.c
@@ -42,6 +42,8 @@ typedef struct
 
 static vlib_node_registration_t bfd_udp4_input_node;
 static vlib_node_registration_t bfd_udp6_input_node;
+static vlib_node_registration_t bfd_udp_echo4_input_node;
+static vlib_node_registration_t bfd_udp_echo6_input_node;
 
 bfd_udp_main_t bfd_udp_main;
 
@@ -594,11 +596,10 @@ typedef enum
   BFD_UDP_INPUT_N_NEXT,
 } bfd_udp_input_next_t;
 
-/* Packet counters */
+/* Packet counters - BFD control frames */
 #define foreach_bfd_udp_error(F)           \
   F (NONE, "good bfd packets (processed)") \
-  F (BAD, "invalid bfd packets")           \
-  F (DISABLED, "bfd packets received on disabled interfaces")
+  F (BAD, "invalid bfd packets")
 
 #define F(sym, string) static char BFD_UDP_ERR_##sym##_STR[] = string;
 foreach_bfd_udp_error (F);
@@ -618,9 +619,32 @@ typedef enum
     BFD_UDP_N_ERROR,
 } bfd_udp_error_t;
 
+/* Packet counters - BFD ECHO packets */
+#define foreach_bfd_udp_echo_error(F)           \
+  F (NONE, "good bfd echo packets (processed)") \
+  F (BAD, "invalid bfd echo packets")
+
+#define F(sym, string) static char BFD_UDP_ECHO_ERR_##sym##_STR[] = string;
+foreach_bfd_udp_echo_error (F);
+#undef F
+
+static char *bfd_udp_echo_error_strings[] = {
+#define F(sym, string) BFD_UDP_ECHO_ERR_##sym##_STR,
+  foreach_bfd_udp_echo_error (F)
+#undef F
+};
+
+typedef enum
+{
+#define F(sym, str) BFD_UDP_ECHO_ERROR_##sym,
+  foreach_bfd_udp_echo_error (F)
+#undef F
+    BFD_UDP_ECHO_N_ERROR,
+} bfd_udp_echo_error_t;
+
 static void
-bfd_udp4_find_headers (vlib_buffer_t * b, const ip4_header_t ** ip4,
-		       const udp_header_t ** udp)
+bfd_udp4_find_headers (vlib_buffer_t * b, ip4_header_t ** ip4,
+		       udp_header_t ** udp)
 {
   /* sanity check first */
   const i32 start = vnet_buffer (b)->ip.start_of_ip_header;
@@ -714,8 +738,8 @@ bfd_udp4_scan (vlib_main_t * vm, vlib_node_runtime_t * rt,
 	 b->current_length, sizeof (*pkt));
       return BFD_UDP_ERROR_BAD;
     }
-  const ip4_header_t *ip4;
-  const udp_header_t *udp;
+  ip4_header_t *ip4;
+  udp_header_t *udp;
   bfd_udp4_find_headers (b, &ip4, &udp);
   if (!ip4 || !udp)
     {
@@ -776,8 +800,8 @@ bfd_udp4_scan (vlib_main_t * vm, vlib_node_runtime_t * rt,
 }
 
 static void
-bfd_udp6_find_headers (vlib_buffer_t * b, const ip6_header_t ** ip6,
-		       const udp_header_t ** udp)
+bfd_udp6_find_headers (vlib_buffer_t * b, ip6_header_t ** ip6,
+		       udp_header_t ** udp)
 {
   /* sanity check first */
   const i32 start = vnet_buffer (b)->ip.start_of_ip_header;
@@ -856,8 +880,8 @@ bfd_udp6_scan (vlib_main_t * vm, vlib_node_runtime_t * rt,
 	 b->current_length, sizeof (*pkt));
       return BFD_UDP_ERROR_BAD;
     }
-  const ip6_header_t *ip6;
-  const udp_header_t *udp;
+  ip6_header_t *ip6;
+  udp_header_t *udp;
   bfd_udp6_find_headers (b, &ip6, &udp);
   if (!ip6 || !udp)
     {
@@ -1057,6 +1081,185 @@ VLIB_REGISTER_NODE (bfd_udp6_input_node, static) = {
 };
 /* *INDENT-ON* */
 
+/**
+ * @brief swap the source and destination IP addresses in the packet
+ */
+static int
+bfd_echo_address_swap (vlib_buffer_t * b, int is_ipv6)
+{
+  udp_header_t *dummy = NULL;
+  if (is_ipv6)
+    {
+      ip6_header_t *ip6 = NULL;
+      bfd_udp6_find_headers (b, &ip6, &dummy);
+      if (!ip6)
+	{
+	  return 0;
+	}
+      ip6_address_t tmp = ip6->dst_address;
+      ip6->dst_address = ip6->src_address;
+      ip6->src_address = tmp;
+      vlib_buffer_advance (b,
+			   (u8 *) ip6 - (u8 *) vlib_buffer_get_current (b));
+    }
+  else
+    {
+      ip4_header_t *ip4 = NULL;
+      bfd_udp4_find_headers (b, &ip4, &dummy);
+      if (!ip4)
+	{
+	  return 0;
+	}
+      ip4_address_t tmp = ip4->dst_address;
+      ip4->dst_address = ip4->src_address;
+      ip4->src_address = tmp;
+      vlib_buffer_advance (b,
+			   (u8 *) ip4 - (u8 *) vlib_buffer_get_current (b));
+    }
+  return 1;
+}
+
+/*
+ * Process a frame of bfd echo packets
+ * Expect 1 packet / frame
+ */
+static uword
+bfd_udp_echo_input (vlib_main_t * vm, vlib_node_runtime_t * rt,
+		    vlib_frame_t * f, int is_ipv6)
+{
+  u32 n_left_from, *from;
+  bfd_input_trace_t *t0;
+
+  from = vlib_frame_vector_args (f);	/* array of buffer indices */
+  n_left_from = f->n_vectors;	/* number of buffer indices */
+
+  while (n_left_from > 0)
+    {
+      u32 bi0;
+      vlib_buffer_t *b0;
+      u32 next0;
+
+      bi0 = from[0];
+      b0 = vlib_get_buffer (vm, bi0);
+
+      /* If this pkt is traced, snapshot the data */
+      if (b0->flags & VLIB_BUFFER_IS_TRACED)
+	{
+	  int len;
+	  t0 = vlib_add_trace (vm, rt, b0, sizeof (*t0));
+	  len = (b0->current_length < sizeof (t0->data)) ? b0->current_length
+	    : sizeof (t0->data);
+	  t0->len = len;
+	  clib_memcpy (t0->data, vlib_buffer_get_current (b0), len);
+	}
+
+      if (bfd_echo_address_swap (b0, is_ipv6))
+	{
+	  /* loop back the packet */
+	  b0->error = rt->errors[BFD_UDP_ERROR_NONE];
+	  if (is_ipv6)
+	    {
+	      vlib_node_increment_counter (vm, bfd_udp_echo6_input_node.index,
+					   b0->error, 1);
+	    }
+	  else
+	    {
+	      vlib_node_increment_counter (vm, bfd_udp_echo4_input_node.index,
+					   b0->error, 1);
+	    }
+	  next0 = BFD_UDP_INPUT_NEXT_REPLY;
+	}
+      else
+	{
+	  b0->error = rt->errors[BFD_UDP_ERROR_BAD];
+	  next0 = BFD_UDP_INPUT_NEXT_NORMAL;
+	}
+
+      vlib_set_next_frame_buffer (vm, rt, next0, bi0);
+
+      from += 1;
+      n_left_from -= 1;
+    }
+
+  return f->n_vectors;
+}
+
+static uword
+bfd_udp_echo4_input (vlib_main_t * vm, vlib_node_runtime_t * rt,
+		     vlib_frame_t * f)
+{
+  return bfd_udp_echo_input (vm, rt, f, 0);
+}
+
+u8 *
+bfd_echo_input_format_trace (u8 * s, va_list * args)
+{
+  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
+  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
+  const bfd_udp_echo_input_trace_t *t =
+    va_arg (*args, bfd_udp_echo_input_trace_t *);
+  if (t->len > STRUCT_SIZE_OF (bfd_pkt_t, head))
+    {
+      s = format (s, "BFD ECHO:\n");
+      s = format (s, "    data: %U", format_hexdump, t->data, t->len);
+    }
+
+  return s;
+}
+
+/*
+ * bfd input graph node declaration
+ */
+/* *INDENT-OFF* */
+VLIB_REGISTER_NODE (bfd_udp_echo4_input_node, static) = {
+  .function = bfd_udp_echo4_input,
+  .name = "bfd-udp-echo4-input",
+  .vector_size = sizeof (u32),
+  .type = VLIB_NODE_TYPE_INTERNAL,
+
+  .n_errors = BFD_UDP_ECHO_N_ERROR,
+  .error_strings = bfd_udp_error_strings,
+
+  .format_trace = bfd_echo_input_format_trace,
+
+  .n_next_nodes = BFD_UDP_INPUT_N_NEXT,
+  .next_nodes =
+      {
+              [BFD_UDP_INPUT_NEXT_NORMAL] = "error-drop",
+              [BFD_UDP_INPUT_NEXT_REPLY] = "ip4-lookup",
+      },
+};
+/* *INDENT-ON* */
+
+static uword
+bfd_udp_echo6_input (vlib_main_t * vm, vlib_node_runtime_t * rt,
+		     vlib_frame_t * f)
+{
+  return bfd_udp_echo_input (vm, rt, f, 1);
+}
+
+/* *INDENT-OFF* */
+VLIB_REGISTER_NODE (bfd_udp_echo6_input_node, static) = {
+  .function = bfd_udp_echo6_input,
+  .name = "bfd-udp-echo6-input",
+  .vector_size = sizeof (u32),
+  .type = VLIB_NODE_TYPE_INTERNAL,
+
+  .n_errors = BFD_UDP_ECHO_N_ERROR,
+  .error_strings = bfd_udp_echo_error_strings,
+
+  .format_trace = bfd_echo_input_format_trace,
+
+  .n_next_nodes = BFD_UDP_INPUT_N_NEXT,
+  .next_nodes =
+      {
+              [BFD_UDP_INPUT_NEXT_NORMAL] = "error-drop",
+              [BFD_UDP_INPUT_NEXT_REPLY] = "ip6-lookup",
+      },
+};
+
+/* *INDENT-ON* */
+
 static clib_error_t *
 bfd_sw_interface_up_down (vnet_main_t * vnm, u32 sw_if_index, u32 flags)
 {
@@ -1093,6 +1296,10 @@ bfd_udp_init (vlib_main_t * vm)
   bfd_udp_main.bfd_main = &bfd_main;
   udp_register_dst_port (vm, UDP_DST_PORT_bfd4, bfd_udp4_input_node.index, 1);
   udp_register_dst_port (vm, UDP_DST_PORT_bfd6, bfd_udp6_input_node.index, 0);
+  udp_register_dst_port (vm, UDP_DST_PORT_bfd_echo4,
+			 bfd_udp_echo4_input_node.index, 1);
+  udp_register_dst_port (vm, UDP_DST_PORT_bfd_echo6,
+			 bfd_udp_echo6_input_node.index, 0);
   return 0;
 }