PUNT socket: External control plane processes connected via UNIX domain sockets.

An external (to VPP) process can register (over the VPP binary API) to
receive control plane packets over a UNIX domain socket. The packets are
prepended with a packet descriptor containing meta-data (if_index of
interface, etc).

Currently only UDP is supported.

The socket supports sending of packets/frames as well.
The sent packet is prepended with a descriptor, telling VPP to
route the packet (via ip4-lookup, ip6-lookup) or as an pre-formed
Ethernet frame that is sent directly to interface-output.

The intended use case for this is for an external DHCP client or
a RIP implementation.

New configuration option:

punt { socket <socket path> }

To register use the punt_socket API message.

TODO:
  - Add support for pre-routing. I.e send L3 packet to given
    TX interface, but do ARP/ND (ip[46]-rewrite)
  - Add test scripts
  - Support for abstract names (starting with \0)
  - Add rate limiting (COP)
  - Support for other protocols, e.g. IPv6 ND

Change-Id: I4a0afc8020deebb3d9d74686dde694ee5bcb8d0f
Signed-off-by: Ole Troan <ot@cisco.com>

src/vnet/ip/punt.h

@@ -20,6 +20,7 @@
 #ifndef included_punt_h
 #define included_punt_h
 
+#include <sys/un.h>
 typedef enum
 {
 #define punt_error(n,s) PUNT_ERROR_##n,
@@ -30,9 +31,56 @@ typedef enum
 
 
 clib_error_t *vnet_punt_add_del (vlib_main_t * vm, u8 ipv,
-				 u8 protocol, u16 port, int is_add);
+				 u8 protocol, u16 port, bool is_add);
+clib_error_t *vnet_punt_socket_add (vlib_main_t * vm, u32 header_version,
+				    bool is_ip4, u8 protocol, u16 port,
+				    char *client_pathname);
+clib_error_t *vnet_punt_socket_del (vlib_main_t * vm, bool is_ip4,
+				    u8 l4_protocol, u16 port);
+char *vnet_punt_get_server_pathname (void);
 
-#endif /* included_punt_h */
+enum punt_action_e
+{
+  PUNT_L2 = 0,
+  PUNT_IP4_ROUTED,
+  PUNT_IP6_ROUTED,
+};
+
+/*
+ * Packet descriptor header. Version 1
+ * If this header changes, the version must also change to notify clients.
+ */
+#define PUNT_PACKETDESC_VERSION 1
+typedef struct __attribute__ ((packed))
+{
+  u32 sw_if_index;		/* RX or TX interface */
+  enum punt_action_e action;
+} punt_packetdesc_t;
+
+/*
+ * Client registration
+ */
+typedef struct
+{
+  u16 port;
+  struct sockaddr_un caddr;
+} punt_client_t;
+
+typedef struct
+{
+  int socket_fd;
+  char sun_path[sizeof (struct sockaddr_un)];
+  punt_client_t *clients_by_dst_port4;
+  punt_client_t *clients_by_dst_port6;
+  u32 unix_file_index;
+  bool is_configured;
+  vlib_node_t *interface_output_node;
+  u32 *ready_fds;
+  u32 *rx_buffers;
+} punt_main_t;
+extern punt_main_t punt_main;
+
+#endif
 
 /*
  * fd.io coding-style-patch-verification: ON

src/vnet/ip/punt_error.def

@@ -17,3 +17,11 @@
 
 punt_error (NONE, "no error")
 punt_error (UDP_PORT, "udp port punt")
+punt_error (SOCKET_RX, "Socket RX")
+punt_error (SOCKET_TX, "Socket TX")
+punt_error (SOCKET_RX_ERROR, "Socket RX error")
+punt_error (SOCKET_TX_ERROR, "Socket TX error")
+punt_error (NOBUFFER, "buffer allocation failure")
+punt_error (READV, "socket read failure")
+punt_error (ACTION, "invalid packet descriptor")
+

src/vpp/api/api.c

@@ -144,6 +144,8 @@ _(IP_SOURCE_AND_PORT_RANGE_CHECK_INTERFACE_ADD_DEL,                     \
   ip_source_and_port_range_check_interface_add_del)                     \
 _(DELETE_SUBIF, delete_subif)                                           \
 _(PUNT, punt)                                                           \
+_(PUNT_SOCKET_REGISTER, punt_socket_register)                           \
+_(PUNT_SOCKET_DEREGISTER, punt_socket_deregister)                       \
 _(FEATURE_ENABLE_DISABLE, feature_enable_disable)
 
 #define QUOTE_(x) #x
@@ -1940,6 +1942,68 @@ vl_api_punt_t_handler (vl_api_punt_t * mp)
   REPLY_MACRO (VL_API_PUNT_REPLY);
 }
 
+static void
+vl_api_punt_socket_register_t_handler (vl_api_punt_socket_register_t * mp)
+{
+  vl_api_punt_socket_register_reply_t *rmp;
+  vlib_main_t *vm = vlib_get_main ();
+  int rv = 0;
+  clib_error_t *error;
+  unix_shared_memory_queue_t *q;
+  u32 handle;
+
+  error = vnet_punt_socket_add (vm, ntohl (mp->header_version),
+				mp->is_ip4, mp->l4_protocol,
+				ntohs (mp->l4_port), (char *) mp->pathname);
+  if (error)
+    {
+      rv = -1;
+      clib_error_report (error);
+    }
+
+  q = vl_api_client_index_to_input_queue (mp->client_index);
+  if (!q)
+    return;
+
+  rmp = vl_msg_api_alloc (sizeof (*rmp));
+  rmp->_vl_msg_id = htons (VL_API_PUNT_SOCKET_REGISTER_REPLY);
+  rmp->context = mp->context;
+  rmp->retval = htonl (rv);
+  char *p = vnet_punt_get_server_pathname ();
+  /* Abstract pathnames start with \0 */
+  memcpy ((char *) rmp->pathname, p, sizeof (rmp->pathname));
+  vl_msg_api_send_shmem (q, (u8 *) & rmp);
+}
+
+static void
+vl_api_punt_socket_deregister_t_handler (vl_api_punt_socket_deregister_t * mp)
+{
+  vl_api_punt_socket_deregister_reply_t *rmp;
+  vlib_main_t *vm = vlib_get_main ();
+  int rv = 0;
+  clib_error_t *error;
+  unix_shared_memory_queue_t *q;
+  u32 handle;
+
+  error = vnet_punt_socket_del (vm, mp->is_ip4, mp->l4_protocol,
+				ntohs (mp->l4_port));
+  if (error)
+    {
+      rv = -1;
+      clib_error_report (error);
+    }
+
+  q = vl_api_client_index_to_input_queue (mp->client_index);
+  if (!q)
+    return;
+
+  rmp = vl_msg_api_alloc (sizeof (*rmp));
+  rmp->_vl_msg_id = htons (VL_API_PUNT_SOCKET_DEREGISTER_REPLY);
+  rmp->context = mp->context;
+  rmp->retval = htonl (rv);
+  vl_msg_api_send_shmem (q, (u8 *) & rmp);
+}
+
 static void
 vl_api_feature_enable_disable_t_handler (vl_api_feature_enable_disable_t * mp)
 {

src/vpp/api/vpe.api

@@ -991,6 +991,39 @@ autoreply define punt {
     u16 l4_port;
 };
 
+/** \brief Punt traffic to the host via socket
+    @param client_index - opaque cookie to identify the sender
+    @param context - sender context, to match reply w/ request
+    @param header_version - expected meta data header version (currently 1)
+    @param is_ip4 - L3 protocol 1 - IPv4, 0 - IPv6
+    @param l4_protocol - L4 protocol to be punted, only UDP (0x11) is supported
+    @param l4_port - TCP/UDP port to be punted
+*/
+define punt_socket_register {
+    u32 client_index;
+    u32 context;
+    u32 header_version;
+    u8 is_ip4;
+    u8 l4_protocol;
+    u16 l4_port;
+    u8 pathname[64];
+};
+
+define punt_socket_register_reply
+{
+  u32 context;
+  i32 retval;
+  u8 pathname[64];
+};
+
+autoreply define punt_socket_deregister {
+    u32 client_index;
+    u32 context;
+    u8 is_ip4;
+    u8 l4_protocol;
+    u16 l4_port;
+};
+
 /** \brief Feature path enable/disable request
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request