Shared memory packet interface (memif) library

Change-Id: I5097462ae85acd705f19e92517c01094dba7565f
Signed-off-by: Jakub Grajciar <grajciar.jakub@gmail.com>

1 files changed, 791 insertions, 0 deletions

diff --git a/extras/libmemif/examples/icmp_responder-epoll/main.c b/extras/libmemif/examples/icmp_responder-epoll/main.c
new file mode 100644
index 00000000000..4172785f0ef
--- /dev/null
+++ b/extras/libmemif/examples/icmp_responder-epoll/main.c
@@ -0,0 +1,791 @@
+/*
+ *------------------------------------------------------------------
+ * Copyright (c) 2017 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 <stdlib.h>
+#include <stdint.h>
+#include <net/if.h>
+#include <sys/types.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <sys/uio.h>
+#include <sys/mman.h>
+#include <sys/prctl.h>
+#include <inttypes.h>
+#include <string.h>
+#include <stdio.h>
+#include <netdb.h>
+#include <linux/ip.h>
+#include <linux/icmp.h>
+#include <arpa/inet.h>
+#include <stdlib.h>
+#include <netinet/if_ether.h>
+#include <net/if_arp.h>
+#include <asm/byteorder.h>
+#include <byteswap.h>
+#include <string.h>
+#include <sys/epoll.h>
+#include <errno.h>
+#include <unistd.h>
+#include <signal.h>
+
+#include <libmemif.h>
+#include <icmp_proto.h>
+
+#define APP_NAME "ICMP_Responder"
+#define IF_NAME  "memif_connection"
+
+
+#ifdef ICMP_DBG
+#define DBG(...) do {                                               \
+                    printf (APP_NAME":%s:%d: ", __func__, __LINE__);         \
+                    printf (__VA_ARGS__);                           \
+                    printf ("\n");                                  \
+                } while (0)
+#else
+#define DBG(...)
+#endif
+
+#define INFO(...) do {                                              \
+                    printf ("INFO: "__VA_ARGS__);                   \
+                    printf ("\n");                                  \
+                } while (0)
+
+/* maximum tx/rx memif buffers */
+#define MAX_MEMIF_BUFS  256
+#define MAX_CONNS       50
+
+int epfd;
+
+typedef struct
+{
+  uint16_t index;
+  /* memif conenction handle */
+  memif_conn_handle_t conn;
+  /* tx buffers */
+  memif_buffer_t *tx_bufs;
+  /* allocated tx buffers counter */
+  /* number of tx buffers pointing to shared memory */
+  uint16_t tx_buf_num;
+  /* rx buffers */
+  memif_buffer_t *rx_bufs;
+  /* allcoated rx buffers counter */
+  /* number of rx buffers pointing to shared memory */
+  uint16_t rx_buf_num;
+  /* interface ip address */
+  uint8_t ip_addr[4];
+} memif_connection_t;
+
+memif_connection_t memif_connection[MAX_CONNS];
+long ctx[MAX_CONNS];
+
+/* print details for all memif connections */
+static void
+print_memif_details ()
+{
+  memif_details_t md;
+  ssize_t buflen;
+  char *buf;
+  int err, i, e;
+  buflen = 2048;
+  buf = malloc (buflen);
+  printf ("MEMIF DETAILS\n");
+  printf ("==============================\n");
+  for (i = 0; i < MAX_CONNS; i++)
+    {
+      memif_connection_t *c = &memif_connection[i];
+
+      memset (&md, 0, sizeof (md));
+      memset (buf, 0, buflen);
+
+      err = memif_get_details (c->conn, &md, buf, buflen);
+      if (err != MEMIF_ERR_SUCCESS)
+	{
+	  if (err != MEMIF_ERR_NOCONN)
+	    INFO ("%s", memif_strerror (err));
+	  continue;
+	}
+
+      printf ("interface index: %d\n", i);
+
+      printf ("\tinterface ip: %u.%u.%u.%u\n",
+	      c->ip_addr[0], c->ip_addr[1], c->ip_addr[2], c->ip_addr[3]);
+      printf ("\tinterface name: %s\n", (char *) md.if_name);
+      printf ("\tapp name: %s\n", (char *) md.inst_name);
+      printf ("\tremote interface name: %s\n", (char *) md.remote_if_name);
+      printf ("\tremote app name: %s\n", (char *) md.remote_inst_name);
+      printf ("\tid: %u\n", md.id);
+      printf ("\tsecret: %s\n", (char *) md.secret);
+      printf ("\trole: ");
+      if (md.role)
+	printf ("slave\n");
+      else
+	printf ("master\n");
+      printf ("\tmode: ");
+      switch (md.mode)
+	{
+	case 0:
+	  printf ("ethernet\n");
+	  break;
+	case 1:
+	  printf ("ip\n");
+	  break;
+	case 2:
+	  printf ("punt/inject\n");
+	  break;
+	default:
+	  printf ("unknown\n");
+	  break;
+	}
+      printf ("\tsocket filename: %s\n", (char *) md.socket_filename);
+      printf ("\trx queues:\n");
+      for (e = 0; e < md.rx_queues_num; e++)
+	{
+	  printf ("\t\tqueue id: %u\n", md.rx_queues[e].qid);
+	  printf ("\t\tring size: %u\n", md.rx_queues[e].ring_size);
+	  printf ("\t\tbuffer size: %u\n", md.rx_queues[e].buffer_size);
+	}
+      printf ("\ttx queues:\n");
+      for (e = 0; e < md.tx_queues_num; e++)
+	{
+	  printf ("\t\tqueue id: %u\n", md.tx_queues[e].qid);
+	  printf ("\t\tring size: %u\n", md.tx_queues[e].ring_size);
+	  printf ("\t\tbuffer size: %u\n", md.tx_queues[e].buffer_size);
+	}
+      printf ("\tlink: ");
+      if (md.link_up_down)
+	printf ("up\n");
+      else
+	printf ("down\n");
+    }
+  free (buf);
+}
+
+int
+add_epoll_fd (int fd, uint32_t events)
+{
+  if (fd < 0)
+    {
+      DBG ("invalid fd %d", fd);
+      return -1;
+    }
+  struct epoll_event evt;
+  memset (&evt, 0, sizeof (evt));
+  evt.events = events;
+  evt.data.fd = fd;
+  if (epoll_ctl (epfd, EPOLL_CTL_ADD, fd, &evt) < 0)
+    {
+      DBG ("epoll_ctl: %s fd %d", strerror (errno), fd);
+      return -1;
+    }
+  DBG ("fd %d added to epoll", fd);
+  return 0;
+}
+
+int
+mod_epoll_fd (int fd, uint32_t events)
+{
+  if (fd < 0)
+    {
+      DBG ("invalid fd %d", fd);
+      return -1;
+    }
+  struct epoll_event evt;
+  memset (&evt, 0, sizeof (evt));
+  evt.events = events;
+  evt.data.fd = fd;
+  if (epoll_ctl (epfd, EPOLL_CTL_MOD, fd, &evt) < 0)
+    {
+      DBG ("epoll_ctl: %s fd %d", strerror (errno), fd);
+      return -1;
+    }
+  DBG ("fd %d moddified on epoll", fd);
+  return 0;
+}
+
+int
+del_epoll_fd (int fd)
+{
+  if (fd < 0)
+    {
+      DBG ("invalid fd %d", fd);
+      return -1;
+    }
+  struct epoll_event evt;
+  memset (&evt, 0, sizeof (evt));
+  if (epoll_ctl (epfd, EPOLL_CTL_DEL, fd, &evt) < 0)
+    {
+      DBG ("epoll_ctl: %s fd %d", strerror (errno), fd);
+      return -1;
+    }
+  DBG ("fd %d removed from epoll", fd);
+  return 0;
+}
+
+/* informs user about connected status. private_ctx is used by user to identify connection
+    (multiple connections WIP) */
+int
+on_connect (memif_conn_handle_t conn, void *private_ctx)
+{
+  INFO ("memif connected!");
+  return 0;
+}
+
+/* informs user about disconnected status. private_ctx is used by user to identify connection
+    (multiple connections WIP) */
+int
+on_disconnect (memif_conn_handle_t conn, void *private_ctx)
+{
+  INFO ("memif disconnected!");
+  return 0;
+}
+
+/* user needs to watch new fd or stop watching fd that is about to be closed.
+    control fd will be modified during connection establishment to minimize CPU usage */
+int
+control_fd_update (int fd, uint8_t events)
+{
+  /* convert memif event definitions to epoll events */
+  if (events & MEMIF_FD_EVENT_DEL)
+    return del_epoll_fd (fd);
+
+  uint32_t evt = 0;
+  if (events & MEMIF_FD_EVENT_READ)
+    evt |= EPOLLIN;
+  if (events & MEMIF_FD_EVENT_WRITE)
+    evt |= EPOLLOUT;
+
+  if (events & MEMIF_FD_EVENT_MOD)
+    return mod_epoll_fd (fd, evt);
+
+  return add_epoll_fd (fd, evt);
+}
+
+int
+icmpr_buffer_alloc (long index, long n, uint16_t qid)
+{
+  memif_connection_t *c = &memif_connection[index];
+  int err;
+  uint16_t r;
+  /* set data pointer to shared memory and set buffer_len to shared mmeory buffer len */
+  err = memif_buffer_alloc (c->conn, qid, c->tx_bufs, n, &r);
+  if (err != MEMIF_ERR_SUCCESS)
+    {
+      INFO ("memif_buffer_alloc: %s", memif_strerror (err));
+      c->tx_buf_num += r;
+      return -1;
+    }
+  c->tx_buf_num += r;
+  DBG ("allocated %d/%ld buffers, %u free buffers", r, n,
+       MAX_MEMIF_BUFS - c->tx_buf_num);
+  return 0;
+}
+
+int
+icmpr_tx_burst (long index, uint16_t qid)
+{
+  memif_connection_t *c = &memif_connection[index];
+  int err;
+  uint16_t r;
+  /* inform peer memif interface about data in shared memory buffers */
+  /* mark memif buffers as free */
+  err = memif_tx_burst (c->conn, qid, c->tx_bufs, c->tx_buf_num, &r);
+  if (err != MEMIF_ERR_SUCCESS)
+    INFO ("memif_tx_burst: %s", memif_strerror (err));
+  DBG ("tx: %d/%u", r, c->tx_buf_num);
+  c->tx_buf_num -= r;
+  return 0;
+}
+
+/* called when event is polled on interrupt file descriptor.
+    there are packets in shared memory ready to be received */
+int
+on_interrupt (memif_conn_handle_t conn, void *private_ctx, uint16_t qid)
+{
+  long index = *((long *) private_ctx);
+  memif_connection_t *c = &memif_connection[index];
+  if (c->index != index)
+    {
+      INFO ("invalid context: %ld/%u", index, c->index);
+      return 0;
+    }
+  int err;
+  uint16_t rx;
+  uint16_t fb;
+  /* receive data from shared memory buffers */
+  err = memif_rx_burst (c->conn, qid, c->rx_bufs, MAX_MEMIF_BUFS, &rx);
+  if (err != MEMIF_ERR_SUCCESS)
+    {
+      INFO ("memif_rx_burst: %s", memif_strerror (err));
+      c->rx_buf_num += rx;
+      goto error;
+    }
+  c->rx_buf_num += rx;
+
+  DBG ("received %d buffers. %u/%u alloc/free buffers",
+       rx, c->rx_buf_num, MAX_MEMIF_BUFS - c->rx_buf_num);
+
+  if (icmpr_buffer_alloc (index, rx, qid) < 0)
+    {
+      INFO ("buffer_alloc error");
+      goto error;
+    }
+  int i;
+  for (i = 0; i < rx; i++)
+    {
+      resolve_packet ((void *) (c->rx_bufs + i)->data,
+		      (c->rx_bufs + i)->data_len,
+		      (void *) (c->tx_bufs + i)->data,
+		      &(c->tx_bufs + i)->data_len, c->ip_addr);
+    }
+
+  /* mark memif buffers and shared memory buffers as free */
+  err = memif_buffer_free (c->conn, qid, c->rx_bufs, rx, &fb);
+  if (err != MEMIF_ERR_SUCCESS)
+    INFO ("memif_buffer_free: %s", memif_strerror (err));
+  c->rx_buf_num -= fb;
+
+  DBG ("freed %d buffers. %u/%u alloc/free buffers",
+       fb, c->rx_buf_num, MAX_MEMIF_BUFS - c->rx_buf_num);
+
+  icmpr_tx_burst (index, qid);
+
+  return 0;
+
+error:
+  err = memif_buffer_free (c->conn, qid, c->rx_bufs, rx, &fb);
+  if (err != MEMIF_ERR_SUCCESS)
+    INFO ("memif_buffer_free: %s", memif_strerror (err));
+  c->rx_buf_num -= fb;
+  DBG ("freed %d buffers. %u/%u alloc/free buffers",
+       fb, c->rx_buf_num, MAX_MEMIF_BUFS - c->rx_buf_num);
+  return 0;
+}
+
+int
+icmpr_memif_create (long index, long mode)
+{
+  if (index >= MAX_CONNS)
+    {
+      INFO ("connection array overflow");
+      return 0;
+    }
+  if (index < 0)
+    {
+      INFO ("don't even try...");
+      return 0;
+    }
+  memif_connection_t *c = &memif_connection[index];
+
+  /* setting memif connection arguments */
+  memif_conn_args_t args;
+  int fd = -1;
+  memset (&args, 0, sizeof (args));
+  args.is_master = mode;
+  args.log2_ring_size = 10;
+  args.buffer_size = 2048;
+  args.num_s2m_rings = 2;
+  args.num_m2s_rings = 2;
+  strncpy ((char *) args.interface_name, IF_NAME, strlen (IF_NAME));
+  strncpy ((char *) args.instance_name, APP_NAME, strlen (APP_NAME));
+  args.mode = 0;
+  /* socket filename is not specified, because this app is supposed to
+     connect to VPP over memif. so default socket filename will be used */
+  /* default socketfile = /run/vpp/memif.sock */
+
+  args.interface_id = index;
+  /* last argument for memif_create (void * private_ctx) is used by user
+     to identify connection. this context is returned with callbacks */
+  int err = memif_create (&c->conn,
+			  &args, on_connect, on_disconnect, on_interrupt,
+			  &ctx[index]);
+  if (err != MEMIF_ERR_SUCCESS)
+    {
+      INFO ("memif_create: %s", memif_strerror (err));
+      return 0;
+    }
+
+  c->index = index;
+  /* alloc memif buffers */
+  c->rx_buf_num = 0;
+  c->rx_bufs =
+    (memif_buffer_t *) malloc (sizeof (memif_buffer_t) * MAX_MEMIF_BUFS);
+  c->tx_buf_num = 0;
+  c->tx_bufs =
+    (memif_buffer_t *) malloc (sizeof (memif_buffer_t) * MAX_MEMIF_BUFS);
+
+  c->ip_addr[0] = 192;
+  c->ip_addr[1] = 168;
+  c->ip_addr[2] = c->index + 1;
+  c->ip_addr[3] = 2;
+  return 0;
+}
+
+int
+icmpr_memif_delete (long index)
+{
+  if (index >= MAX_CONNS)
+    {
+      INFO ("connection array overflow");
+      return 0;
+    }
+  if (index < 0)
+    {
+      INFO ("don't even try...");
+      return 0;
+    }
+  memif_connection_t *c = &memif_connection[index];
+
+  if (c->rx_bufs)
+    free (c->rx_bufs);
+  c->rx_bufs = NULL;
+  c->rx_buf_num = 0;
+  if (c->tx_bufs)
+    free (c->tx_bufs);
+  c->tx_bufs = NULL;
+  c->tx_buf_num = 0;
+
+  int err;
+  /* disconenct then delete memif connection */
+  err = memif_delete (&c->conn);
+  if (err != MEMIF_ERR_SUCCESS)
+    INFO ("memif_delete: %s", memif_strerror (err));
+  if (c->conn != NULL)
+    INFO ("memif delete fail");
+  return 0;
+}
+
+void
+print_help ()
+{
+  printf ("LIBMEMIF EXAMPLE APP: %s", APP_NAME);
+#ifdef ICMP_DBG
+  printf (" (debug)");
+#endif
+  printf ("\n");
+  printf ("==============================\n");
+  printf ("libmemif version: %s", LIBMEMIF_VERSION);
+#ifdef MEMIF_DBG
+  printf (" (debug)");
+#endif
+  printf ("\n");
+  printf ("memif version: %d\n", MEMIF_VERSION);
+  printf ("commands:\n");
+  printf ("\thelp - prints this help\n");
+  printf ("\texit - exit app\n");
+  printf
+    ("\tconn <index> <mode> - create memif. index is also used as interface id, mode 0 = slave 1 = master\n");
+  printf ("\tdel  <index> - delete memif\n");
+  printf ("\tshow - show connection details\n");
+  printf ("\tip-set <index> <ip-addr> - set interface ip address\n");
+  printf
+    ("\trx-mode <index> <qid> <polling|interrupt> - set queue rx mode\n");
+}
+
+int
+icmpr_free ()
+{
+  /* application cleanup */
+  int err;
+  long i;
+  for (i = 0; i < MAX_CONNS; i++)
+    {
+      memif_connection_t *c = &memif_connection[i];
+      if (c->conn)
+	icmpr_memif_delete (i);
+    }
+
+  err = memif_cleanup ();
+  if (err != MEMIF_ERR_SUCCESS)
+    INFO ("memif_delete: %s", memif_strerror (err));
+
+  return 0;
+}
+
+int
+icmpr_set_ip (long index, char *ip)
+{
+  if (index >= MAX_CONNS)
+    {
+      INFO ("connection array overflow");
+      return 0;
+    }
+  if (index < 0)
+    {
+      INFO ("don't even try...");
+      return 0;
+    }
+  memif_connection_t *c = &memif_connection[index];
+  if (c->conn == NULL)
+    {
+      INFO ("no connection at index %ld", index);
+      return 0;
+    }
+
+  char *end;
+  char *ui;
+  uint8_t tmp[4];
+  ui = strtok (ip, ".");
+  if (ui == NULL)
+    goto error;
+  tmp[0] = strtol (ui, &end, 10);
+
+  ui = strtok (NULL, ".");
+  if (ui == NULL)
+    goto error;
+  tmp[1] = strtol (ui, &end, 10);
+
+  ui = strtok (NULL, ".");
+  if (ui == NULL)
+    goto error;
+  tmp[2] = strtol (ui, &end, 10);
+
+  ui = strtok (NULL, ".");
+  if (ui == NULL)
+    goto error;
+  tmp[3] = strtol (ui, &end, 10);
+
+  c->ip_addr[0] = tmp[0];
+  c->ip_addr[1] = tmp[1];
+  c->ip_addr[2] = tmp[2];
+  c->ip_addr[3] = tmp[3];
+
+  INFO ("memif %ld ip address set to %u.%u.%u.%u",
+	index, c->ip_addr[0], c->ip_addr[1], c->ip_addr[2], c->ip_addr[3]);
+
+  return 0;
+
+error:
+  INFO ("invalid ip address");
+  return 0;
+}
+
+int
+icmpr_set_rx_mode (long index, long qid, char *mode)
+{
+  if (index >= MAX_CONNS)
+    {
+      INFO ("connection array overflow");
+      return 0;
+    }
+  if (index < 0)
+    {
+      INFO ("don't even try...");
+      return 0;
+    }
+  memif_connection_t *c = &memif_connection[index];
+
+  if (c->conn == NULL)
+    {
+      INFO ("no connection at index %ld", index);
+      return 0;
+    }
+
+  if (strncmp (mode, "interrupt", 9) == 0)
+    {
+      memif_set_rx_mode (c->conn, MEMIF_RX_MODE_INTERRUPT, qid);
+    }
+
+  else if (strncmp (mode, "polling", 7) == 0)
+    {
+      memif_set_rx_mode (c->conn, MEMIF_RX_MODE_POLLING, qid);
+    }
+  else
+    INFO ("expected rx mode <interrupt|polling>");
+  return 0;
+}
+
+int
+user_input_handler ()
+{
+  int i;
+  char *in = (char *) malloc (256);
+  char *ui = fgets (in, 256, stdin);
+  char *end;
+  long a;
+  if (in[0] == '\n')
+    goto done;
+  ui = strtok (in, " ");
+  if (strncmp (ui, "exit", 4) == 0)
+    {
+      free (in);
+      icmpr_free ();
+      exit (EXIT_SUCCESS);
+    }
+  else if (strncmp (ui, "help", 4) == 0)
+    {
+      print_help ();
+      goto done;
+    }
+  else if (strncmp (ui, "conn", 4) == 0)
+    {
+      ui = strtok (NULL, " ");
+      if (ui != NULL)
+	a = strtol (ui, &end, 10);
+      else
+	{
+	  INFO ("expected id");
+	  goto done;
+	}
+      ui = strtok (NULL, " ");
+      if (ui != NULL)
+	icmpr_memif_create (a, strtol (ui, &end, 10));
+      else
+	INFO ("expected mode <0|1>");
+      goto done;
+    }
+  else if (strncmp (ui, "del", 3) == 0)
+    {
+      ui = strtok (NULL, " ");
+      if (ui != NULL)
+	icmpr_memif_delete (strtol (ui, &end, 10));
+      else
+	INFO ("expected id");
+      goto done;
+    }
+  else if (strncmp (ui, "show", 4) == 0)
+    {
+      print_memif_details ();
+      goto done;
+    }
+  else if (strncmp (ui, "ip-set", 6) == 0)
+    {
+      ui = strtok (NULL, " ");
+      if (ui != NULL)
+	icmpr_set_ip (strtol (ui, &end, 10), strtok (NULL, " "));
+      else
+	INFO ("expected id");
+      goto done;
+    }
+  else if (strncmp (ui, "rx-mode", 7) == 0)
+    {
+      ui = strtok (NULL, " ");
+      if (ui != NULL)
+	a = strtol (ui, &end, 10);
+      else
+	{
+	  INFO ("expected id");
+	  goto done;
+	}
+      ui = strtok (NULL, " ");
+      if (ui != NULL)
+	icmpr_set_rx_mode (a, strtol (ui, &end, 10), strtok (NULL, " "));
+      else
+	INFO ("expected qid");
+      goto done;
+    }
+  else
+    {
+      DBG ("unknown command: %s", ui);
+      goto done;
+    }
+
+  return 0;
+done:
+  free (in);
+  return 0;
+}
+
+int
+poll_event (int timeout)
+{
+  struct epoll_event evt, *e;
+  int app_err = 0, memif_err = 0, en = 0;
+  int tmp, nfd;
+  uint32_t events = 0;
+  memset (&evt, 0, sizeof (evt));
+  evt.events = EPOLLIN | EPOLLOUT;
+  sigset_t sigset;
+  sigemptyset (&sigset);
+  en = epoll_pwait (epfd, &evt, 1, timeout, &sigset);
+  if (en < 0)
+    {
+      DBG ("epoll_pwait: %s", strerror (errno));
+      return -1;
+    }
+  if (en > 0)
+    {
+      /* this app does not use any other file descriptors than stds and memif control fds */
+      if (evt.data.fd > 2)
+	{
+	  /* event of memif control fd */
+	  /* convert epolle events to memif events */
+	  if (evt.events & EPOLLIN)
+	    events |= MEMIF_FD_EVENT_READ;
+	  if (evt.events & EPOLLOUT)
+	    events |= MEMIF_FD_EVENT_WRITE;
+	  if (evt.events & EPOLLERR)
+	    events |= MEMIF_FD_EVENT_ERROR;
+	  memif_err = memif_control_fd_handler (evt.data.fd, events);
+	  if (memif_err != MEMIF_ERR_SUCCESS)
+	    INFO ("memif_control_fd_handler: %s", memif_strerror (memif_err));
+	}
+      else if (evt.data.fd == 0)
+	{
+	  app_err = user_input_handler ();
+	}
+      else
+	{
+	  DBG ("unexpected event at memif_epfd. fd %d", evt.data.fd);
+	}
+    }
+
+  if ((app_err < 0) || (memif_err < 0))
+    {
+      if (app_err < 0)
+	DBG ("user input handler error");
+      if (memif_err < 0)
+	DBG ("memif control fd handler error");
+      return -1;
+    }
+
+  return 0;
+}
+
+int
+main ()
+{
+  epfd = epoll_create (1);
+  add_epoll_fd (0, EPOLLIN);
+
+  /* initialize memory interface */
+  int err, i;
+  /* if valid callback is passed as argument, fd event polling will be done by user
+     all file descriptors and events will be passed to user in this callback */
+  /* if callback is set to NULL libmemif will handle fd event polling */
+  err = memif_init (control_fd_update, APP_NAME);
+  if (err != MEMIF_ERR_SUCCESS)
+    INFO ("memif_init: %s", memif_strerror (err));
+
+  for (i = 0; i < MAX_CONNS; i++)
+    {
+      memif_connection[i].conn = NULL;
+      ctx[i] = i;
+    }
+
+  print_help ();
+
+  /* main loop */
+  while (1)
+    {
+      if (poll_event (-1) < 0)
+	{
+	  DBG ("poll_event error!");
+	}
+    }
+}