udp: add udp decapsulation

Possibility to register a port via CLI or API to decap incoming UDP
packets:
 - For CLI, a user needs to specify the inner protocol (only MPLS
   supported for now)
 - For API, the protocol is specified by index
Added unittests

Type: feature
Change-Id: Ifedd86d8db2e355b7618472554fd67d77a13a4aa
Signed-off-by: Arthur de Kerhor <arthurdekerhor@gmail.com>

1 files changed, 106 insertions, 0 deletions

diff --git a/src/vnet/udp/udp_decap.c b/src/vnet/udp/udp_decap.c
new file mode 100644
index 00000000000..7337ac17ee9
--- /dev/null
+++ b/src/vnet/udp/udp_decap.c
@@ -0,0 +1,106 @@
+/*
+ * Copyright (c) 2021 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <vnet/udp/udp.h>
+
+uword
+unformat_next_node (unformat_input_t *input, va_list *args)
+{
+  vlib_main_t *vm = va_arg (*args, vlib_main_t *);
+  u32 *node_index = va_arg (*args, u32 *);
+  if (unformat (input, "mpls"))
+    *node_index = vlib_get_node_by_name (vm, (u8 *) "mpls-input")->index;
+  else if (unformat (input, "ip4"))
+    *node_index = vlib_get_node_by_name (vm, (u8 *) "ip4-input")->index;
+  else if (unformat (input, "ip6"))
+    *node_index = vlib_get_node_by_name (vm, (u8 *) "ip6-input")->index;
+  else
+    return 0;
+  return 1;
+}
+
+static clib_error_t *
+udp_decap_cli (vlib_main_t *vm, unformat_input_t *input,
+	       vlib_cli_command_t *cmd_arg)
+{
+  unformat_input_t _line_input, *line_input = &_line_input;
+  clib_error_t *error = NULL;
+  u8 is_add = 1, is_ip4 = 1;
+  int i = 0;
+  u16 port = 0;
+  u32 node_index = ~0;
+
+  if (!unformat_user (input, unformat_line_input, line_input))
+    return 0;
+
+  while (unformat_check_input (line_input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (line_input, "add"))
+	is_add = 1;
+      else if (unformat (line_input, "del"))
+	is_add = 0;
+      else if (unformat (line_input, "ipv4"))
+	is_ip4 = 1;
+      else if (unformat (line_input, "ipv6"))
+	is_ip4 = 0;
+      else if (unformat (line_input, "%d", &i))
+	port = i;
+      else if (unformat (line_input, "next-proto %U", unformat_next_node, vm,
+			 &node_index))
+	;
+      else
+	{
+	  error = clib_error_return (0, "parse error: '%U'",
+				     format_unformat_error, line_input);
+	  goto done;
+	}
+    }
+  if (port == 0)
+    {
+      error = clib_error_return (0, "missing port");
+      goto done;
+    }
+  if (is_add && node_index == ~0)
+    {
+      error = clib_error_return (0, "missing protocol");
+      goto done;
+    }
+  if (is_add)
+    udp_register_dst_port (vm, port, node_index, is_ip4);
+  else
+    udp_unregister_dst_port (vm, port, is_ip4);
+
+done:
+  unformat_free (line_input);
+  return error;
+}
+
+/*?
+ * Register a port to decapsulate incoming UDP encapsulated packets.
+ *
+ * @cliexpar
+ * @clistart
+ * udp decap add ipv4 1234 next-proto mpls
+ * @cliend
+ * @cliexcmd{udp decap [add|del] [ipv4|ipv6] <dst-port> next-proto
+<inner-protocol>}
+?*/
+
+VLIB_CLI_COMMAND (udp_decap_add_command, static) = {
+  .path = "udp decap",
+  .short_help =
+    "udp decap [add|del] [ipv4|ipv6] <dst-port> next-proto <inner-protocol>",
+  .function = udp_decap_cli,
+};
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