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>

3 files changed, 189 insertions, 9 deletions

diff --git a/src/vnet/udp/udp.api b/src/vnet/udp/udp.api
index 2cd2bd50272..02176be7c2b 100644
--- a/src/vnet/udp/udp.api
+++ b/src/vnet/udp/udp.api
@@ -45,6 +45,26 @@ typedef udp_encap
   u32 id;
 };
 
+enum udp_decap_next_proto
+{
+    UDP_API_DECAP_PROTO_IP4,
+    UDP_API_DECAP_PROTO_IP6,
+    UDP_API_DECAP_PROTO_MPLS,
+};
+
+/**
+ * @brief UDP Decap object
+ * @param is_ip4 - IPv4 if non-zero, else IPv6
+ * @param port - port to listen on for the decap
+ * @param next_proto - the protocol of the inner header
+ */
+typedef udp_decap
+{
+  u8 is_ip4;
+  u16 port;
+  vl_api_udp_decap_next_proto_t next_proto;
+};
+
 /**
  * @brief Add UDP encap
  * @param client_index - opaque cookie to identify the sender
@@ -103,6 +123,21 @@ define udp_encap_details
   vl_api_udp_encap_t udp_encap;
 };
 
+/**
+ * @brief Add/Del UDP decap
+ * @param client_index - opaque cookie to identify the sender
+ * @param context - sender context, to match reply w/ request
+ * @param is_add - add decap if non-zero, else delete
+ * @param udp_decap - UDP decap description
+ */
+autoreply define udp_decap_add_del
+{
+  u32 client_index;
+  u32 context;
+  bool is_add;
+  vl_api_udp_decap_t udp_decap;
+};
+
 /*
  * Local Variables:
  * eval: (c-set-style "gnu")
diff --git a/src/vnet/udp/udp_api.c b/src/vnet/udp/udp_api.c
index 5b9d8945642..6ba92bbf207 100644
--- a/src/vnet/udp/udp_api.c
+++ b/src/vnet/udp/udp_api.c
@@ -16,6 +16,7 @@
 #include <vnet/vnet.h>
 #include <vlibmemory/api.h>
 
+#include <vnet/udp/udp_local.h>
 #include <vnet/udp/udp_encap.h>
 #include <vnet/fib/fib_table.h>
 #include <vnet/ip/ip_types_api.h>
@@ -38,11 +39,11 @@
 
 #include <vlibapi/api_helper_macros.h>
 
-
-#define foreach_udp_api_msg            \
-_(UDP_ENCAP_DEL, udp_encap_del)        \
-_(UDP_ENCAP_ADD, udp_encap_add)        \
-_(UDP_ENCAP_DUMP, udp_encap_dump)
+#define foreach_udp_api_msg                                                   \
+  _ (UDP_ENCAP_DEL, udp_encap_del)                                            \
+  _ (UDP_ENCAP_ADD, udp_encap_add)                                            \
+  _ (UDP_ENCAP_DUMP, udp_encap_dump)                                          \
+  _ (UDP_DECAP_ADD_DEL, udp_decap_add_del)
 
 static void
 send_udp_encap_details (const udp_encap_t * ue, vl_api_registration_t * reg,
@@ -92,8 +93,7 @@ send_udp_encap_details (const udp_encap_t * ue, vl_api_registration_t * reg,
 }
 
 static void
-vl_api_udp_encap_dump_t_handler (vl_api_udp_encap_dump_t * mp,
-				 vlib_main_t * vm)
+vl_api_udp_encap_dump_t_handler (vl_api_udp_encap_dump_t *mp)
 {
   vl_api_registration_t *reg;
   udp_encap_t *ue;
@@ -111,7 +111,7 @@ vl_api_udp_encap_dump_t_handler (vl_api_udp_encap_dump_t * mp,
 }
 
 static void
-vl_api_udp_encap_add_t_handler (vl_api_udp_encap_add_t * mp, vlib_main_t * vm)
+vl_api_udp_encap_add_t_handler (vl_api_udp_encap_add_t *mp)
 {
   vl_api_udp_encap_add_reply_t *rmp;
   ip46_address_t src_ip, dst_ip;
@@ -152,7 +152,7 @@ done:
 }
 
 static void
-vl_api_udp_encap_del_t_handler (vl_api_udp_encap_del_t * mp, vlib_main_t * vm)
+vl_api_udp_encap_del_t_handler (vl_api_udp_encap_del_t *mp)
 {
   vl_api_udp_encap_del_reply_t *rmp;
   int rv = 0;
@@ -162,6 +162,45 @@ vl_api_udp_encap_del_t_handler (vl_api_udp_encap_del_t * mp, vlib_main_t * vm)
   REPLY_MACRO (VL_API_UDP_ENCAP_DEL_REPLY);
 }
 
+u32
+udp_api_decap_proto_to_index (vlib_main_t *vm,
+			      vl_api_udp_decap_next_proto_t iproto)
+{
+  switch (iproto)
+    {
+    case UDP_API_DECAP_PROTO_IP4:
+      return vlib_get_node_by_name (vm, (u8 *) "ip4-input")->index;
+    case UDP_API_DECAP_PROTO_IP6:
+      return vlib_get_node_by_name (vm, (u8 *) "ip6-input")->index;
+    case UDP_API_DECAP_PROTO_MPLS:
+      return vlib_get_node_by_name (vm, (u8 *) "mpls-input")->index;
+    }
+  return ~0;
+}
+
+static void
+vl_api_udp_decap_add_del_t_handler (vl_api_udp_decap_add_del_t *mp)
+{
+  vl_api_udp_decap_add_del_reply_t *rmp;
+  vlib_main_t *vm = vlib_get_main ();
+  int rv = 0;
+
+  if (mp->is_add)
+    {
+      u32 node_index =
+	udp_api_decap_proto_to_index (vm, ntohl (mp->udp_decap.next_proto));
+      if (node_index == ~0)
+	rv = VNET_API_ERROR_INVALID_PROTOCOL;
+      else
+	udp_register_dst_port (vm, ntohs (mp->udp_decap.port), node_index,
+			       mp->udp_decap.is_ip4);
+    }
+  else
+    udp_unregister_dst_port (vm, ntohs (mp->udp_decap.port),
+			     mp->udp_decap.is_ip4);
+  REPLY_MACRO (VL_API_UDP_DECAP_ADD_DEL_REPLY);
+}
+
 #define vl_msg_name_crc_list
 #include <vnet/udp/udp.api.h>
 #undef vl_msg_name_crc_list
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,
+};
\ No newline at end of file