Shared memory packet interface (memif) library

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

6 files changed, 3674 insertions, 0 deletions

diff --git a/extras/libmemif/src/libmemif.h b/extras/libmemif/src/libmemif.h
new file mode 100644
index 00000000000..3732be688e6
--- /dev/null
+++ b/extras/libmemif/src/libmemif.h
@@ -0,0 +1,442 @@
+/*
+ *------------------------------------------------------------------
+ * 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.
+ *------------------------------------------------------------------
+ */
+
+/** @file */
+
+#ifndef _LIBMEMIF_H_
+#define _LIBMEMIF_H_
+
+/** Libmemif version. */
+#define LIBMEMIF_VERSION "1.0"
+/** Default name of application using libmemif. */
+#define MEMIF_DEFAULT_APP_NAME "libmemif-app"
+
+#include <inttypes.h>
+
+#include <memif.h>
+
+/*! Error codes */
+typedef enum
+{
+  MEMIF_ERR_SUCCESS = 0,	/*!< success */
+/* SYSCALL ERRORS */
+  MEMIF_ERR_SYSCALL,		/*!< other syscall error */
+  MEMIF_ERR_ACCES,		/*!< permission denied */
+  MEMIF_ERR_NO_FILE,		/*!< file does not exist */
+  MEMIF_ERR_FILE_LIMIT,		/*!< system open file limit */
+  MEMIF_ERR_PROC_FILE_LIMIT,	/*!< process open file limit */
+  MEMIF_ERR_ALREADY,		/*!< connection already requested */
+  MEMIF_ERR_AGAIN,		/*!< fd is not socket, or operation would block */
+  MEMIF_ERR_BAD_FD,		/*!< invalid fd */
+  MEMIF_ERR_NOMEM,		/*!< out of memory */
+/* LIBMEMIF ERRORS */
+  MEMIF_ERR_INVAL_ARG,		/*!< invalid argument */
+  MEMIF_ERR_NOCONN,		/*!< handle points to no connection */
+  MEMIF_ERR_CONN,		/*!< handle points to existing connection */
+  MEMIF_ERR_CB_FDUPDATE,	/*!< user defined callback memif_control_fd_update_t error */
+  MEMIF_ERR_FILE_NOT_SOCK,	/*!< file specified by socket filename 
+				   exists, but it's not socket */
+  MEMIF_ERR_NO_SHMFD,		/*!< missing shm fd */
+  MEMIF_ERR_COOKIE,		/*!< wrong cookie on ring */
+  MEMIF_ERR_NOBUF_RING,		/*!< ring buffer full */
+  MEMIF_ERR_NOBUF,		/*!< not enough memif buffers */
+  MEMIF_ERR_NOBUF_DET,		/*!< memif details needs larger buffer */
+  MEMIF_ERR_INT_WRITE,		/*!< send interrupt error */
+  MEMIF_ERR_MFMSG,		/*!< malformed msg received */
+  MEMIF_ERR_QID,		/*!< invalid queue id */
+/* MEMIF PROTO ERRORS */
+  MEMIF_ERR_PROTO,		/*!< incompatible protocol version */
+  MEMIF_ERR_ID,			/*!< unmatched interface id */
+  MEMIF_ERR_ACCSLAVE,		/*!< slave cannot accept connection requests */
+  MEMIF_ERR_ALRCONN,		/*!< memif is already connected */
+  MEMIF_ERR_MODE,		/*!< mode mismatch */
+  MEMIF_ERR_SECRET,		/*!< secret mismatch */
+  MEMIF_ERR_NOSECRET,		/*!< secret required */
+  MEMIF_ERR_MAXREG,		/*!< max region limit reached */
+  MEMIF_ERR_MAXRING,		/*!< max ring limit reached */
+  MEMIF_ERR_NO_INTFD,		/*!< missing interrupt fd */
+  MEMIF_ERR_DISCONNECT,		/*!< disconenct received */
+  MEMIF_ERR_DISCONNECTED,	/*!< peer interface disconnected */
+  MEMIF_ERR_UNKNOWN_MSG,	/*!< unknown message type */
+} memif_err_t;
+
+/**
+ * @defgroup MEMIF_FD_EVENT Types of events that need to be watched for specific fd.
+ *
+ * @{
+ */
+
+/** user needs to set events that occured on fd and pass them to memif_control_fd_handler */
+#define MEMIF_FD_EVENT_READ  (1 << 0)
+#define MEMIF_FD_EVENT_WRITE (1 << 1)
+/** inform libmemif that error occured on fd */
+#define MEMIF_FD_EVENT_ERROR (1 << 2)
+/** if set, informs that fd is going to be closed (user may want to stop watching for events on this fd) */
+#define MEMIF_FD_EVENT_DEL   (1 << 3)
+/** update events */
+#define MEMIF_FD_EVENT_MOD   (1 << 4)
+/** @} */
+
+/** *brief Memif connection handle
+    pointer of type void, pointing to internal structure
+*/
+typedef void *memif_conn_handle_t;
+/**
+ * @defgroup CALLBACKS Callback functions definitions
+ *
+ * @{
+ */
+
+/** \brief Memif control file descriptor update (callback function)
+    @param fd - new file descriptor to watch
+    @param events - event type(s) to watch for
+
+    This callback is called when there is new fd to watch for events on
+    or if fd is about to be closed (user mey want to stop watching for events on this fd).
+*/
+typedef int (memif_control_fd_update_t) (int fd, uint8_t events);
+
+/** \brief Memif connection status update (callback function)
+    @param conn - memif connection handle
+    @param private_ctx - private context
+
+    Informs user about connection status connected/disconnected.
+    On connected -> start watching for events on interrupt fd (optional).
+*/
+typedef int (memif_connection_update_t) (memif_conn_handle_t conn,
+					 void *private_ctx);
+
+/** \brief Memif interrupt occured (callback function)
+    @param conn - memif connection handle
+    @param private_ctx - private context
+    @param qid - queue id on which interrupt occured
+
+    Called when event is received on interrupt fd.
+*/
+typedef int (memif_interrupt_t) (memif_conn_handle_t conn, void *private_ctx,
+				 uint16_t qid);
+/** @} */
+
+/**
+ * @defgroup ARGS_N_BUFS Connection arguments and buffers
+ *
+ * @{
+ */
+
+/** \brief Memif connection arguments
+    @param socket_filename - socket filename
+    @param secret - otional parameter used as interface autenthication
+    @param num_s2m_rings - number of slave to master rings
+    @param num_m2s_rings - number of master to slave rings
+    @param buffer_size - size of buffer in shared memory
+    @param log2_ring_size - logarithm base 2 of ring size
+    @param is_master - 0 == master, 1 == slave
+    @param interface_id - id used to identify peer connection
+    @param interface_name - interface name
+    @param instance_name - application name
+    @param mode - 0 == ethernet, 1 == ip , 2 == punt/inject
+*/
+typedef struct
+{
+  uint8_t *socket_filename;	/*!< default = /run/vpp/memif.sock */
+  uint8_t secret[24];		/*!< optional (interface authentication) */
+
+  uint8_t num_s2m_rings;	/*!< default = 1 */
+  uint8_t num_m2s_rings;	/*!< default = 1 */
+  uint16_t buffer_size;		/*!< default = 2048 */
+  memif_log2_ring_size_t log2_ring_size;	/*!< default = 10 (1024) */
+  uint8_t is_master;
+
+  memif_interface_id_t interface_id;
+  uint8_t interface_name[32];
+  uint8_t instance_name[32];
+  memif_interface_mode_t mode:8;
+} memif_conn_args_t;
+
+/*! memif receive mode */
+typedef enum
+{
+  MEMIF_RX_MODE_INTERRUPT = 0,	/*!< interrupt mode */
+  MEMIF_RX_MODE_POLLING		/*!< polling mode */
+} memif_rx_mode_t;
+
+/** \brief Memif buffer
+    @param desc_index - ring descriptor index
+    @param buffer_len - shared meory buffer length
+    @param data_len - data length
+    @param data - pointer to shared memory data
+*/
+typedef struct
+{
+  uint16_t desc_index;
+  uint32_t buffer_len;
+  uint32_t data_len;
+  void *data;
+} memif_buffer_t;
+/** @} */
+
+/**
+ * @defgroup MEMIF_DETAILS Memif details structs
+ *
+ * @{
+ */
+
+/** \brief Memif queue details
+    @param qid - queue id
+    @param ring_size - size of ring buffer in sharem memory
+    @param buffer_size - buffer size on sharem memory
+*/
+typedef struct
+{
+  uint8_t qid;
+  uint32_t ring_size;
+  uint16_t buffer_size;
+  /* add ring information */
+} memif_queue_details_t;
+
+/** \brief Memif details
+    @param if_name - interface name
+    @param inst_name - application name
+    @param remote_if_name - peer interface name
+    @param remote_inst_name - peer application name
+    @param id - connection id
+    @param secret - secret
+    @param role - 0 = master, 1 = slave
+    @param mode - 0 = ethernet, 1 = ip , 2 = punt/inject
+    @param socket_filename = socket filename
+    @param rx_queues_num - number of receive queues
+    @param tx_queues_num - number of transmit queues
+    @param rx_queues - struct containing receive queue details
+    @param tx_queues - struct containing transmit queue details
+    @param link_up_down - 1 = up (connected), 2 = down (disconnected)
+*/
+typedef struct
+{
+  uint8_t *if_name;
+  uint8_t *inst_name;
+  uint8_t *remote_if_name;
+  uint8_t *remote_inst_name;
+
+  uint32_t id;
+  uint8_t *secret;		/* optional */
+  uint8_t role;			/* 0 = master, 1 = slave */
+  uint8_t mode;			/* 0 = ethernet, 1 = ip, 2 = punt/inject */
+  uint8_t *socket_filename;
+  uint8_t rx_queues_num;
+  uint8_t tx_queues_num;
+  memif_queue_details_t *rx_queues;
+  memif_queue_details_t *tx_queues;
+
+  uint8_t link_up_down;		/* 1 = up, 0 = down */
+} memif_details_t;
+/** @} */
+
+/**
+ * @defgroup API_CALLS Api calls
+ *
+ * @{
+ */
+
+/** \biref Memif get queue event file descriptor
+    @param conn - memif connection handle
+    @param qid - queue id
+    @param[out] fd - returns event file descriptor
+
+    \return memif_err_t
+*/
+
+int memif_get_queue_efd (memif_conn_handle_t conn, uint16_t qid, int *fd);
+
+/** \brief Memif set rx mode
+    @param conn - memif connection handle
+    @param rx_mode - receive mode
+    @param qid - queue id
+
+    \return memif_err_t
+*/
+int memif_set_rx_mode (memif_conn_handle_t conn, memif_rx_mode_t rx_mode,
+		       uint16_t qid);
+
+/** \brief Memif strerror
+    @param err_code - error code
+
+    Converts error code to error message.
+    
+    \return Error string
+*/
+char *memif_strerror (int err_code);
+
+/** \brief Memif get details
+    @param conn - memif conenction handle
+    @param md - pointer to memif details struct
+    @param buf - buffer containing details strings
+    @param buflen - length of buffer
+
+    \return memif_err_t
+*/
+int memif_get_details (memif_conn_handle_t conn, memif_details_t * md,
+		       char *buf, ssize_t buflen);
+
+/** \brief Memif initialization
+    @param on_control_fd_update - if control fd updates inform user to watch new fd
+    @param app_name - application name
+
+    if param on_control_fd_update is set to NULL,
+    libmemif will handle file descriptor event polling
+    if a valid callback is set, file descriptor event polling needs to be done by
+    user application, all file descriptors and event types will be passed in
+    this callback to user application
+
+    Initialize internal libmemif structures. Create timerfd (used to periodically request connection by
+    disconnected memifs in slave mode, with no additional API call). This fd is passed to user with memif_control_fd_update_t
+    timer is inactive at this state. It activates with if there is at least one memif in slave mode.
+
+    \return memif_err_t
+*/
+int memif_init (memif_control_fd_update_t * on_control_fd_update,
+		char *app_name);
+
+/** \brief Memif cleanup
+
+    Free libmemif internal allocations.
+
+    \return 0
+*/
+int memif_cleanup ();
+
+/** \brief Memory interface create function
+    @param conn - connection handle for user app
+    @param args - memory interface connection arguments
+    @param on_connect - inform user about connected status
+    @param on_disconnect - inform user about disconnected status
+    @param on_interrupt - informs user about interrupt, if set to null user will not be notified about interrupt, user can use memif_get_queue_efd call to get interrupt fd to poll for events
+    @param private_ctx - private contex passed back to user with callback
+
+    Creates memory interface.
+     
+    SLAVE-MODE - 
+        Start timer that will send events to timerfd. If this fd is passed to memif_control_fd_handler
+        every disconnected memif in slave mode will send connection request.
+        On success new fd is passed to user with memif_control_fd_update_t.
+
+    MASTER-MODE - 
+        Create listener socket and pass fd to user with memif_cntrol_fd_update_t.
+        If this fd is passed to memif_control_fd_handler accept will be called and
+        new fd will be passed to user with memif_control_fd_update_t.
+
+
+    \return memif_err_t
+*/
+int memif_create (memif_conn_handle_t * conn, memif_conn_args_t * args,
+		  memif_connection_update_t * on_connect,
+		  memif_connection_update_t * on_disconnect,
+		  memif_interrupt_t * on_interrupt, void *private_ctx);
+
+/** \brief Memif control file descriptor handler
+    @param fd - file descriptor on which the event occured
+    @param events - event type(s) that occured
+
+    If event occures on any control fd, call memif_control_fd_handler.
+    Internal - lib will "identify" fd (timerfd, lsitener, control) and handle event accordingly.
+ 
+    FD-TYPE - 
+        TIMERFD - 
+            Every disconnected memif in slave mode will request connection.
+        LISTENER or CONTROL - 
+            Handle socket messaging (internal connection establishment).
+        INTERRUPT - 
+            Call on_interrupt callback (if set).
+        
+    \return memif_err_t
+
+*/
+int memif_control_fd_handler (int fd, uint8_t events);
+
+/** \brief Memif delete
+    @param conn - pointer to memif connection handle
+
+
+    disconnect session (free queues and regions, close file descriptors, unmap shared memory)
+    set connection handle to NULL, to avoid possible double free
+
+    \return memif_err_t
+*/
+int memif_delete (memif_conn_handle_t * conn);
+
+/** \brief Memif buffer alloc
+    @param conn - memif conenction handle
+    @param qid - number indentifying queue
+    @param bufs - memif buffers
+    @param count - number of memif buffers to allocate
+    @param count_out - returns number of allocated buffers
+
+    \return memif_err_t
+*/
+int memif_buffer_alloc (memif_conn_handle_t conn, uint16_t qid,
+			memif_buffer_t * bufs, uint16_t count,
+			uint16_t * count_out);
+
+/** \brief Memif buffer free
+    @param conn - memif conenction handle
+    @param qid - number indentifying queue
+    @param bufs - memif buffers
+    @param count - number of memif buffers to free
+    @param count_out - returns number of freed buffers
+
+    \return memif_err_t
+*/
+int memif_buffer_free (memif_conn_handle_t conn, uint16_t qid,
+		       memif_buffer_t * bufs, uint16_t count,
+		       uint16_t * count_out);
+
+/** \brief Memif transmit buffer burst
+    @param conn - memif conenction handle
+    @param qid - number indentifying queue
+    @param bufs - memif buffers
+    @param count - number of memif buffers to transmit
+    @param tx - returns number of transmitted buffers
+
+    \return memif_err_t
+*/
+int memif_tx_burst (memif_conn_handle_t conn, uint16_t qid,
+		    memif_buffer_t * bufs, uint16_t count, uint16_t * tx);
+
+/** \brief Memif receive buffer burst
+    @param conn - memif conenction handle
+    @param qid - number indentifying queue
+    @param bufs - memif buffers
+    @param count - number of memif buffers to receive
+    @param rx - returns number of received buffers
+
+    \return memif_err_t
+*/
+int memif_rx_burst (memif_conn_handle_t conn, uint16_t qid,
+		    memif_buffer_t * bufs, uint16_t count, uint16_t * rx);
+
+/** \brief Memif poll event
+    @param timeout - timeout in seconds
+
+    Passive event polling - 
+    timeout = 0 - dont wait for event, check event queue if there is an event and return.
+    timeout = -1 - wait until event
+
+    \return memif_err_t
+*/
+int memif_poll_event (int timeout);
+/** @} */
+
+#endif /* _LIBMEMIF_H_ */
diff --git a/extras/libmemif/src/main.c b/extras/libmemif/src/main.c
new file mode 100644
index 00000000000..d1b59eea8fe
--- /dev/null
+++ b/extras/libmemif/src/main.c
@@ -0,0 +1,1810 @@
+/*
+ *------------------------------------------------------------------
+ * 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 <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 <errno.h>
+#include <sys/stat.h>
+#include <sys/eventfd.h>
+#include <sys/timerfd.h>
+#include <sys/epoll.h>
+#include <signal.h>
+
+/* memif protocol msg, ring and descriptor definitions */
+#include <memif.h>
+/* memif api */
+#include <libmemif.h>
+/* socket messaging functions */
+#include <socket.h>
+/* private structs and functions */
+#include <memif_private.h>
+
+#define ERRLIST_LEN 36
+#define MAX_ERRBUF_LEN 256
+
+#if __x86_x64__
+#define MEMIF_MEMORY_BARRIER() __builtin_ia32_sfence ()
+#else
+#define MEMIF_MEORY_BARRIER() __sync_synchronize ()
+#endif /* __x86_x64__ */
+
+libmemif_main_t libmemif_main;
+int memif_epfd;
+
+static char memif_buf[MAX_ERRBUF_LEN];
+
+const char *memif_errlist[ERRLIST_LEN] = {	/* MEMIF_ERR_SUCCESS */
+  "Success.",
+  /* MEMIF_ERR_SYSCALL */
+  "Unspecified syscall error (build with -DMEMIF_DBG or make debug).",
+  /* MEMIF_ERR_ACCES */
+  "Permission to resoure denied.",
+  /* MEMIF_ERR_NO_FILE */
+  "Socket file does not exist",
+  /* MEMIF_ERR_FILE_LIMIT */
+  "System limit on total numer of open files reached.",
+  /* MEMIF_ERR_PROC_FILE_LIMIT */
+  "Per-process limit on total number of open files reached.",
+  /* MEMIF_ERR_ALREADY */
+  "Connection already requested.",
+  /* MEMIF_ERR_AGAIN */
+  "File descriptor refers to file other than socket, or operation would block.",
+  /* MEMIF_ERR_BAD_FD */
+  "Bad file descriptor.",
+  /* MEMIF_ERR_NOMEM */
+  "Out of memory.",
+  /* MEMIF_ERR_INVAL_ARG */
+  "Invalid argument.",
+  /* MEMIF_ERR_NOCONN */
+  "Memif connection handle does not point to existing conenction",
+  /* MEMIF_ERR_CONN */
+  "Memif connection handle points to existing connection",
+  /* MEMIF_ERR_CB_FDUPDATE */
+  "Callback memif_control_fd_update_t returned error",
+  /* MEMIF_ERR_FILE_NOT_SOCK */
+  "File specified by socket filename exists and is not socket.",
+  /* MEMIF_ERR_NO_SHMFD */
+  "Missing shared memory file descriptor. (internal error)",
+  /* MEMIF_ERR_COOKIE */
+  "Invalid cookie on ring. (internal error)",
+  /* MEMIF_ERR_NOBUF_RING */
+  "Ring buffer full.",
+  /* MEMIF_ERR_NOBUF */
+  "Not enough memif buffers. There are unreceived data in shared memory.",
+  /* MEMIF_ERR_NOBUF_DET */
+  "Not enough space for memif details in suplied buffer. String data might be malformed.",
+  /* MEMIF_ERR_INT_WRITE */
+  "Send interrupt error.",
+  /* MEMIF_ERR_MFMSG */
+  "Malformed message received on control channel.",
+  /* MEMIF_ERR_QID */
+  "Invalid queue id",
+  /* MEMIF_ERR_PROTO */
+  "Incompatible memory interface protocol version.",
+  /* MEMIF_ERR_ID */
+  "Unmatched interface id.",
+  /* MEMIF_ERR_ACCSLAVE */
+  "Slave cannot accept connection reqest.",
+  /* MEMIF_ERR_ALRCONN */
+  "Interface is already connected.",
+  /* MEMIF_ERR_MODE */
+  "Mode mismatch.",
+  /* MEMIF_ERR_SECRET */
+  "Secret mismatch.",
+  /* MEMIF_ERR_NOSECRET */
+  "Secret required.",
+  /* MEMIF_ERR_MAXREG */
+  "Limit on total number of regions reached.",
+  /* MEMIF_ERR_MAXRING */
+  "Limit on total number of ring reached.",
+  /* MEMIF_ERR_NO_INTFD */
+  "Missing interrupt file descriptor. (internal error)",
+  /* MEMIF_ERR_DISCONNECT */
+  "Interface received disconnect request.",
+  /* MEMIF_ERR_DISCONNECTED */
+  "Interface is disconnected.",
+  /* MEMIF_ERR_UNKNOWN_MSG */
+  "Unknown message type received on control channel. (internal error)"
+};
+
+#define MEMIF_ERR_UNDEFINED "undefined error"
+
+char *
+memif_strerror (int err_code)
+{
+  if (err_code >= ERRLIST_LEN)
+    {
+      strncpy (memif_buf, MEMIF_ERR_UNDEFINED, strlen (MEMIF_ERR_UNDEFINED));
+      memif_buf[strlen (MEMIF_ERR_UNDEFINED)] = '\0';
+    }
+  else
+    {
+      strncpy (memif_buf, memif_errlist[err_code],
+	       strlen (memif_errlist[err_code]));
+      memif_buf[strlen (memif_errlist[err_code])] = '\0';
+    }
+  return memif_buf;
+}
+
+#define DBG_TX_BUF (0)
+#define DBG_RX_BUF (1)
+
+#ifdef MEMIF_DBG_SHM
+static void
+print_bytes (void *data, uint16_t len, uint8_t q)
+{
+  if (q == DBG_TX_BUF)
+    printf ("\nTX:\n\t");
+  else
+    printf ("\nRX:\n\t");
+  int i;
+  for (i = 0; i < len; i++)
+    {
+      if (i % 8 == 0)
+	printf ("\n%d:\t", i);
+      printf ("%02X ", ((uint8_t *) (data))[i]);
+    }
+  printf ("\n\n");
+}
+#endif /* MEMIF_DBG */
+
+int
+memif_syscall_error_handler (int err_code)
+{
+  DBG_UNIX ("%s", strerror (err_code));
+
+  if (err_code == 0)
+    return MEMIF_ERR_SUCCESS;
+  if (err_code == EACCES)
+    return MEMIF_ERR_ACCES;
+  if (err_code == ENFILE)
+    return MEMIF_ERR_FILE_LIMIT;
+  if (err_code == EMFILE)
+    return MEMIF_ERR_PROC_FILE_LIMIT;
+  if (err_code == ENOMEM)
+    return MEMIF_ERR_NOMEM;
+/* connection refused if master dows not exist
+    this error would spam the user until master was created */
+  if (err_code == ECONNREFUSED)
+    return MEMIF_ERR_SUCCESS;
+  if (err_code == EALREADY)
+    return MEMIF_ERR_ALREADY;
+  if (err_code == EAGAIN)
+    return MEMIF_ERR_AGAIN;
+  if (err_code == EBADF)
+    return MEMIF_ERR_BAD_FD;
+  if (err_code == ENOENT)
+    return MEMIF_ERR_NO_FILE;
+
+  /* other syscall errors */
+  return MEMIF_ERR_SYSCALL;
+}
+
+static int
+memif_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 (memif_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;
+}
+
+static int
+memif_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 (memif_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;
+}
+
+static int
+memif_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 (memif_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;
+}
+
+int
+memif_control_fd_update (int fd, uint8_t events)
+{
+  if (events & MEMIF_FD_EVENT_DEL)
+    return memif_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 memif_mod_epoll_fd (fd, evt);
+
+  return memif_add_epoll_fd (fd, evt);
+}
+
+int
+add_list_elt (memif_list_elt_t * e, memif_list_elt_t ** list, uint16_t * len)
+{
+  libmemif_main_t *lm = &libmemif_main;
+
+  int i;
+  for (i = 0; i < *len; i++)
+    {
+      if ((*list)[i].data_struct == NULL)
+	{
+	  (*list)[i].key = e->key;
+	  (*list)[i].data_struct = e->data_struct;
+	  return i;
+	}
+    }
+  memif_list_elt_t *tmp;
+  tmp = realloc (*list, sizeof (memif_list_elt_t) * *len * 2);
+  if (tmp == NULL)
+    return -1;
+
+  for (i = *len; i < *len * 2; i++)
+    {
+      tmp[i].key = -1;
+      tmp[i].data_struct = NULL;
+    }
+
+  tmp[*len].key = e->key;
+  tmp[*len].data_struct = e->data_struct;
+  i = *len;
+  *len = *len * 2;
+  *list = tmp;
+
+  return i;
+}
+
+int
+get_list_elt (memif_list_elt_t ** e, memif_list_elt_t * list, uint16_t len,
+	      int key)
+{
+  if (key == -1)
+    {
+      *e = NULL;
+      return -1;
+    }
+  int i;
+  for (i = 0; i < len; i++)
+    {
+      if (list[i].key == key)
+	{
+	  *e = &list[i];
+	  return 0;
+	}
+    }
+  *e = NULL;
+  return -1;
+}
+
+/* does not free memory, only marks element as free */
+int
+free_list_elt (memif_list_elt_t * list, uint16_t len, int key)
+{
+  int i;
+  for (i = 0; i < len; i++)
+    {
+      if (list[i].key == key)
+	{
+	  list[i].key = -1;
+	  list[i].data_struct = NULL;
+	  return 0;
+	}
+    }
+
+  return -1;
+}
+
+int
+free_list_elt_ctx (memif_list_elt_t * list, uint16_t len,
+		   memif_connection_t * ctx)
+{
+  int i;
+  for (i = 0; i < len; i++)
+    {
+      if (list[i].key == -1)
+	{
+	  if (list[i].data_struct == ctx)
+	    {
+	      list[i].data_struct = NULL;
+	      return 0;
+	    }
+	}
+    }
+
+  return -1;
+}
+
+static void
+memif_control_fd_update_register (memif_control_fd_update_t * cb)
+{
+  libmemif_main_t *lm = &libmemif_main;
+  lm->control_fd_update = cb;
+}
+
+int
+memif_init (memif_control_fd_update_t * on_control_fd_update, char *app_name)
+{
+  int err = MEMIF_ERR_SUCCESS;	/* 0 */
+  libmemif_main_t *lm = &libmemif_main;
+
+  if (app_name)
+    {
+      lm->app_name = malloc (strlen (app_name) + sizeof (char));
+      memset (lm->app_name, 0, strlen (app_name) + sizeof (char));
+      strncpy ((char *) lm->app_name, app_name, strlen (app_name));
+    }
+  else
+    {
+      lm->app_name = malloc (strlen (MEMIF_DEFAULT_APP_NAME) + sizeof (char));
+      memset (lm->app_name, 0, strlen (app_name) + sizeof (char));
+      strncpy ((char *) lm->app_name, MEMIF_DEFAULT_APP_NAME,
+	       strlen (MEMIF_DEFAULT_APP_NAME));
+    }
+
+  /* register control fd update callback */
+  if (on_control_fd_update != NULL)
+    memif_control_fd_update_register (on_control_fd_update);
+  else
+    {
+      memif_epfd = epoll_create (1);
+      memif_control_fd_update_register (memif_control_fd_update);
+      DBG ("libmemif event polling initialized");
+    }
+
+  memset (&lm->ms, 0, sizeof (memif_socket_t));
+
+  lm->control_list_len = 2;
+  lm->interrupt_list_len = 2;
+  lm->listener_list_len = 1;
+  lm->pending_list_len = 1;
+
+  lm->control_list =
+    malloc (sizeof (memif_list_elt_t) * lm->control_list_len);
+  lm->interrupt_list =
+    malloc (sizeof (memif_list_elt_t) * lm->interrupt_list_len);
+  lm->listener_list =
+    malloc (sizeof (memif_list_elt_t) * lm->listener_list_len);
+  lm->pending_list =
+    malloc (sizeof (memif_list_elt_t) * lm->pending_list_len);
+
+  int i;
+  for (i = 0; i < lm->control_list_len; i++)
+    {
+      lm->control_list[i].key = -1;
+      lm->control_list[i].data_struct = NULL;
+    }
+  for (i = 0; i < lm->interrupt_list_len; i++)
+    {
+      lm->interrupt_list[i].key = -1;
+      lm->interrupt_list[i].data_struct = NULL;
+    }
+  for (i = 0; i < lm->listener_list_len; i++)
+    {
+      lm->listener_list[i].key = -1;
+      lm->listener_list[i].data_struct = NULL;
+    }
+  for (i = 0; i < lm->pending_list_len; i++)
+    {
+      lm->pending_list[i].key = -1;
+      lm->pending_list[i].data_struct = NULL;
+    }
+
+  lm->disconn_slaves = 0;
+
+  lm->timerfd = timerfd_create (CLOCK_REALTIME, TFD_NONBLOCK);
+  if (lm->timerfd < 0)
+    {
+      err = errno;
+      DBG ("timerfd: %s", strerror (err));
+      return memif_syscall_error_handler (err);
+    }
+
+  lm->arm.it_value.tv_sec = 2;
+  lm->arm.it_value.tv_nsec = 0;
+  lm->arm.it_interval.tv_sec = 2;
+  lm->arm.it_interval.tv_nsec = 0;
+  memset (&lm->disarm, 0, sizeof (lm->disarm));
+
+  if (lm->control_fd_update (lm->timerfd, MEMIF_FD_EVENT_READ) < 0)
+    {
+      DBG ("callback type memif_control_fd_update_t error!");
+      return MEMIF_ERR_CB_FDUPDATE;
+    }
+
+  return 0;
+}
+
+static inline memif_ring_t *
+memif_get_ring (memif_connection_t * conn, memif_ring_type_t type,
+		uint16_t ring_num)
+{
+  if (&conn->regions[0] == NULL)
+    return NULL;
+  void *p = conn->regions[0].shm;
+  int ring_size =
+    sizeof (memif_ring_t) +
+    sizeof (memif_desc_t) * (1 << conn->run_args.log2_ring_size);
+  p += (ring_num + type * conn->run_args.num_s2m_rings) * ring_size;
+
+  return (memif_ring_t *) p;
+}
+
+int
+memif_set_rx_mode (memif_conn_handle_t c, memif_rx_mode_t rx_mode,
+		   uint16_t qid)
+{
+  memif_connection_t *conn = (memif_connection_t *) c;
+  if (conn == NULL)
+    return MEMIF_ERR_NOCONN;
+  uint8_t num =
+    (conn->args.is_master) ? conn->run_args.num_s2m_rings : conn->run_args.
+    num_m2s_rings;
+  if (qid >= num)
+    return MEMIF_ERR_QID;
+
+  conn->rx_queues[qid].ring->flags = rx_mode;
+  DBG ("rx_mode flag: %u", conn->rx_queues[qid].ring->flags);
+  return MEMIF_ERR_SUCCESS;
+}
+
+int
+memif_create (memif_conn_handle_t * c, memif_conn_args_t * args,
+	      memif_connection_update_t * on_connect,
+	      memif_connection_update_t * on_disconnect,
+	      memif_interrupt_t * on_interrupt, void *private_ctx)
+{
+  int err, i, index, sockfd = -1;
+  memif_list_elt_t list_elt;
+  memif_connection_t *conn = (memif_connection_t *) * c;
+  if (conn != NULL)
+    {
+      DBG ("This handle already points to existing memif.");
+      return MEMIF_ERR_CONN;
+    }
+  conn = (memif_connection_t *) malloc (sizeof (memif_connection_t));
+  if (conn == NULL)
+    {
+      err = memif_syscall_error_handler (errno);
+      goto error;
+    }
+  memset (conn, 0, sizeof (memif_connection_t));
+
+  libmemif_main_t *lm = &libmemif_main;
+
+  conn->args.interface_id = args->interface_id;
+
+  if (args->log2_ring_size == 0)
+    args->log2_ring_size = MEMIF_DEFAULT_LOG2_RING_SIZE;
+  if (args->buffer_size == 0)
+    args->buffer_size = MEMIF_DEFAULT_BUFFER_SIZE;
+  if (args->num_s2m_rings == 0)
+    args->num_s2m_rings = MEMIF_DEFAULT_TX_QUEUES;
+  if (args->num_m2s_rings == 0)
+    args->num_m2s_rings = MEMIF_DEFAULT_RX_QUEUES;
+
+  conn->args.num_s2m_rings = args->num_s2m_rings;
+  conn->args.num_m2s_rings = args->num_m2s_rings;
+  conn->args.buffer_size = args->buffer_size;
+  conn->args.log2_ring_size = args->log2_ring_size;
+  conn->args.is_master = args->is_master;
+  conn->args.mode = args->mode;
+  conn->msg_queue = NULL;
+  conn->regions = NULL;
+  conn->tx_queues = NULL;
+  conn->rx_queues = NULL;
+  conn->fd = -1;
+  conn->on_connect = on_connect;
+  conn->on_disconnect = on_disconnect;
+  conn->on_interrupt = on_interrupt;
+  conn->private_ctx = private_ctx;
+  memset (&conn->run_args, 0, sizeof (memif_conn_run_args_t));
+
+  uint8_t l = strlen ((char *) args->interface_name);
+  strncpy ((char *) conn->args.interface_name, (char *) args->interface_name,
+	   l);
+
+  l = strlen ((char *) args->instance_name);
+  strncpy ((char *) conn->args.instance_name, (char *) args->instance_name,
+	   l);
+
+  /* allocate and initialize socket_filename so it can be copyed to sun_path
+     without memory leaks */
+  conn->args.socket_filename = malloc (sizeof (char *) * 108);
+  memset (conn->args.socket_filename, 0, 108 * sizeof (char *));
+
+  if (args->socket_filename)
+    {
+      if (conn->args.socket_filename == NULL)
+	{
+	  err = memif_syscall_error_handler (errno);
+	  goto error;
+	}
+      strncpy ((char *) conn->args.socket_filename,
+	       (char *) args->socket_filename,
+	       strlen ((char *) args->socket_filename));
+    }
+  else
+    {
+      uint16_t sdl = strlen (MEMIF_DEFAULT_SOCKET_DIR);
+      uint16_t sfl = strlen (MEMIF_DEFAULT_SOCKET_FILENAME);
+      if (conn->args.socket_filename == NULL)
+	{
+	  err = memif_syscall_error_handler (errno);
+	  goto error;
+	}
+      strncpy ((char *) conn->args.socket_filename,
+	       MEMIF_DEFAULT_SOCKET_DIR, sdl);
+      conn->args.socket_filename[sdl] = '/';
+      strncpy ((char *) (conn->args.socket_filename + 1 + sdl),
+	       MEMIF_DEFAULT_SOCKET_FILENAME, sfl);
+    }
+
+  if (args->secret)
+    {
+      l = strlen ((char *) args->secret);
+      strncpy ((char *) conn->args.secret, (char *) args->secret, l);
+    }
+
+  if (conn->args.is_master)
+    {
+      conn->run_args.buffer_size = conn->args.buffer_size;
+      memif_socket_t *ms;
+      memif_list_elt_t elt;
+      for (i = 0; i < lm->listener_list_len; i++)
+	{
+	  if ((ms =
+	       (memif_socket_t *) lm->listener_list[i].data_struct) != NULL)
+	    {
+	      if (strncmp
+		  ((char *) ms->filename, (char *) conn->args.socket_filename,
+		   strlen ((char *) ms->filename)) == 0)
+		{
+		  /* add interface to listener socket */
+		  elt.key = conn->args.interface_id;
+		  *c = elt.data_struct = conn;
+		  add_list_elt (&elt, &ms->interface_list,
+				&ms->interface_list_len);
+		  ms->use_count++;
+		  conn->listener_fd = ms->fd;
+		  break;
+		}
+	    }
+	  else
+	    {
+	      struct stat file_stat;
+	      if (stat ((char *) conn->args.socket_filename, &file_stat) == 0)
+		{
+		  if (S_ISSOCK (file_stat.st_mode))
+		    unlink ((char *) conn->args.socket_filename);
+		  else
+		    return memif_syscall_error_handler (errno);
+		}
+	      DBG ("creating socket file");
+	      ms = malloc (sizeof (memif_socket_t));
+	      ms->filename = malloc (strlen ((char *) conn->args.
+					     socket_filename) +
+				     sizeof (char));
+	      memset (ms->filename, 0,
+		      strlen ((char *) conn->args.socket_filename) +
+		      sizeof (char));
+	      strncpy ((char *) ms->filename,
+		       (char *) conn->args.socket_filename,
+		       strlen ((char *) conn->args.socket_filename));
+	      ms->interface_list_len = 1;
+	      ms->interface_list =
+		malloc (sizeof (memif_list_elt_t) * ms->interface_list_len);
+	      ms->interface_list[0].key = -1;
+	      ms->interface_list[0].data_struct = NULL;
+	      struct sockaddr_un un = { 0 };
+	      int on = 1;
+
+	      ms->fd = socket (AF_UNIX, SOCK_SEQPACKET, 0);
+	      if (ms->fd < 0)
+		{
+		  err = memif_syscall_error_handler (errno);
+		  goto error;
+		}
+	      DBG ("socket %d created", ms->fd);
+	      un.sun_family = AF_UNIX;
+	      strncpy ((char *) un.sun_path, (char *) ms->filename,
+		       sizeof (un.sun_path) - 1);
+	      DBG ("sockopt");
+	      if (setsockopt
+		  (ms->fd, SOL_SOCKET, SO_PASSCRED, &on, sizeof (on)) < 0)
+		{
+		  err = memif_syscall_error_handler (errno);
+		  goto error;
+		}
+	      DBG ("bind");
+	      if (bind (ms->fd, (struct sockaddr *) &un, sizeof (un)) < 0)
+		{
+		  err = memif_syscall_error_handler (errno);
+		  goto error;
+		}
+	      DBG ("listen");
+	      if (listen (ms->fd, 1) < 0)
+		{
+		  err = memif_syscall_error_handler (errno);
+		  goto error;
+		}
+	      DBG ("stat");
+	      if (stat ((char *) ms->filename, &file_stat) < 0)
+		{
+		  err = memif_syscall_error_handler (errno);
+		  goto error;
+		}
+
+	      /* add interface to listener socket */
+	      elt.key = conn->args.interface_id;
+	      *c = elt.data_struct = conn;
+	      add_list_elt (&elt, &ms->interface_list,
+			    &ms->interface_list_len);
+	      ms->use_count = 1;
+	      conn->listener_fd = ms->fd;
+
+	      /* add listener socket to libmemif main */
+	      elt.key = ms->fd;
+	      elt.data_struct = ms;
+	      add_list_elt (&elt, &lm->listener_list, &lm->listener_list_len);
+	      lm->control_fd_update (ms->fd, MEMIF_FD_EVENT_READ);
+	      break;
+	    }
+	}
+    }
+  else
+    {
+      if (lm->disconn_slaves == 0)
+	{
+	  if (timerfd_settime (lm->timerfd, 0, &lm->arm, NULL) < 0)
+	    {
+	      err = memif_syscall_error_handler (errno);
+	      goto error;
+	    }
+	}
+
+      lm->disconn_slaves++;
+
+      list_elt.key = -1;
+      *c = list_elt.data_struct = conn;
+      if ((index =
+	   add_list_elt (&list_elt, &lm->control_list,
+			 &lm->control_list_len)) < 0)
+	{
+	  err = MEMIF_ERR_NOMEM;
+	  goto error;
+	}
+    }
+
+  conn->index = index;
+
+  return 0;
+
+error:
+  if (sockfd > 0)
+    close (sockfd);
+  sockfd = -1;
+  if (conn->args.socket_filename)
+    free (conn->args.socket_filename);
+  if (conn != NULL)
+    free (conn);
+  *c = conn = NULL;
+  return err;
+}
+
+int
+memif_control_fd_handler (int fd, uint8_t events)
+{
+  int i, rv, sockfd = -1, err = MEMIF_ERR_SUCCESS;	/* 0 */
+  uint16_t num;
+  memif_list_elt_t *e = NULL;
+  memif_connection_t *conn;
+  libmemif_main_t *lm = &libmemif_main;
+  if (fd == lm->timerfd)
+    {
+      uint64_t b;
+      ssize_t size;
+      size = read (fd, &b, sizeof (b));
+      for (i = 0; i < lm->control_list_len; i++)
+	{
+	  if ((lm->control_list[i].key < 0)
+	      && (lm->control_list[i].data_struct != NULL))
+	    {
+	      conn = lm->control_list[i].data_struct;
+	      if (conn->args.is_master)
+		continue;
+
+	      struct sockaddr_un sun;
+	      sockfd = socket (AF_UNIX, SOCK_SEQPACKET, 0);
+	      if (sockfd < 0)
+		{
+		  err = memif_syscall_error_handler (errno);
+		  goto error;
+		}
+
+	      sun.sun_family = AF_UNIX;
+
+	      strncpy (sun.sun_path, conn->args.socket_filename,
+		       sizeof (sun.sun_path) - 1);
+
+	      if (connect (sockfd, (struct sockaddr *) &sun,
+			   sizeof (struct sockaddr_un)) == 0)
+		{
+		  conn->fd = sockfd;
+		  conn->read_fn = memif_conn_fd_read_ready;
+		  conn->write_fn = memif_conn_fd_write_ready;
+		  conn->error_fn = memif_conn_fd_error;
+
+		  lm->control_list[conn->index].key = conn->fd;
+
+		  lm->control_fd_update (sockfd,
+					 MEMIF_FD_EVENT_READ |
+					 MEMIF_FD_EVENT_WRITE);
+
+		  lm->disconn_slaves--;
+		  if (lm->disconn_slaves == 0)
+		    {
+		      if (timerfd_settime (lm->timerfd, 0, &lm->disarm, NULL)
+			  < 0)
+			{
+			  err = memif_syscall_error_handler (errno);
+			  goto error;
+			}
+		    }
+		}
+	      else
+		{
+		  err = memif_syscall_error_handler (errno);
+		  goto error;
+		}
+	    }
+	}
+    }
+  else
+    {
+      get_list_elt (&e, lm->interrupt_list, lm->interrupt_list_len, fd);
+      if (e != NULL)
+	{
+	  if (((memif_connection_t *) e->data_struct)->on_interrupt != NULL)
+	    {
+	      num =
+		(((memif_connection_t *) e->data_struct)->args.
+		 is_master) ? ((memif_connection_t *) e->data_struct)->
+		run_args.num_s2m_rings : ((memif_connection_t *) e->
+					  data_struct)->run_args.
+		num_m2s_rings;
+	      for (i = 0; i < num; i++)
+		{
+		  if (((memif_connection_t *) e->data_struct)->rx_queues[i].
+		      int_fd == fd)
+		    {
+		      ((memif_connection_t *) e->data_struct)->on_interrupt ((void *) e->data_struct, ((memif_connection_t *) e->data_struct)->private_ctx, i);
+		      return MEMIF_ERR_SUCCESS;
+		    }
+		}
+	    }
+	  return MEMIF_ERR_SUCCESS;
+	}
+      get_list_elt (&e, lm->listener_list, lm->listener_list_len, fd);
+      if (e != NULL)
+	{
+	  memif_conn_fd_accept_ready ((memif_socket_t *) e->data_struct);
+	  return MEMIF_ERR_SUCCESS;
+	}
+
+      get_list_elt (&e, lm->pending_list, lm->pending_list_len, fd);
+      if (e != NULL)
+	{
+	  memif_read_ready (fd);
+	  return MEMIF_ERR_SUCCESS;
+	}
+
+      get_list_elt (&e, lm->control_list, lm->control_list_len, fd);
+      if (e != NULL)
+	{
+	  if (events & MEMIF_FD_EVENT_READ)
+	    {
+	      err =
+		((memif_connection_t *) e->data_struct)->read_fn (e->
+								  data_struct);
+	      if (err != MEMIF_ERR_SUCCESS)
+		return err;
+	    }
+	  if (events & MEMIF_FD_EVENT_WRITE)
+	    {
+	      err =
+		((memif_connection_t *) e->data_struct)->write_fn (e->
+								   data_struct);
+	      if (err != MEMIF_ERR_SUCCESS)
+		return err;
+	    }
+	  if (events & MEMIF_FD_EVENT_ERROR)
+	    {
+	      err =
+		((memif_connection_t *) e->data_struct)->error_fn (e->
+								   data_struct);
+	      if (err != MEMIF_ERR_SUCCESS)
+		return err;
+	    }
+	}
+    }
+
+  return MEMIF_ERR_SUCCESS;	/* 0 */
+
+error:
+  if (sockfd > 0)
+    close (sockfd);
+  sockfd = -1;
+  return err;
+}
+
+int
+memif_poll_event (int timeout)
+{
+  libmemif_main_t *lm = &libmemif_main;
+  memif_list_elt_t *elt;
+  struct epoll_event evt, *e;
+  int en = 0, err = MEMIF_ERR_SUCCESS, i = 0;	/* 0 */
+  uint16_t num;
+  uint32_t events = 0;
+  memset (&evt, 0, sizeof (evt));
+  evt.events = EPOLLIN | EPOLLOUT;
+  sigset_t sigset;
+  sigemptyset (&sigset);
+  en = epoll_pwait (memif_epfd, &evt, 1, timeout, &sigset);
+  if (en < 0)
+    {
+      DBG ("epoll_pwait: %s", strerror (errno));
+      return -1;
+    }
+  if (en > 0)
+    {
+      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;
+      err = memif_control_fd_handler (evt.data.fd, events);
+      return err;
+    }
+  return 0;
+}
+
+static void
+memif_msg_queue_free (memif_msg_queue_elt_t ** e)
+{
+  if (*e == NULL)
+    return;
+  memif_msg_queue_free (&(*e)->next);
+  free (*e);
+  *e = NULL;
+  return;
+}
+
+/* send disconnect msg and close interface */
+int
+memif_disconnect_internal (memif_connection_t * c)
+{
+  if (c == NULL)
+    {
+      DBG ("no connection");
+      return MEMIF_ERR_NOCONN;
+    }
+  uint16_t num;
+  int err = MEMIF_ERR_SUCCESS, i;	/* 0 */
+  memif_queue_t *mq;
+  libmemif_main_t *lm = &libmemif_main;
+  memif_list_elt_t *e;
+
+  c->on_disconnect ((void *) c, c->private_ctx);
+
+  if (c->fd > 0)
+    {
+      memif_msg_send_disconnect (c->fd, "interface deleted", 0);
+      lm->control_fd_update (c->fd, MEMIF_FD_EVENT_DEL);
+      close (c->fd);
+    }
+  get_list_elt (&e, lm->control_list, lm->control_list_len, c->fd);
+  if (e != NULL)
+    {
+      if (c->args.is_master)
+	free_list_elt (lm->control_list, lm->control_list_len, c->fd);
+      e->key = c->fd = -1;
+    }
+
+  if (c->tx_queues != NULL)
+    {
+      num =
+	(c->args.is_master) ? c->run_args.num_m2s_rings : c->run_args.
+	num_s2m_rings;
+      for (i = 0; i < num; i++)
+	{
+	  mq = &c->tx_queues[i];
+	  if (mq != NULL)
+	    {
+	      if (mq->int_fd > 0)
+		close (mq->int_fd);
+	      free_list_elt (lm->interrupt_list, lm->interrupt_list_len,
+			     mq->int_fd);
+	      mq->int_fd = -1;
+	    }
+	}
+      free (c->tx_queues);
+      c->tx_queues = NULL;
+    }
+
+  if (c->rx_queues != NULL)
+    {
+      num =
+	(c->args.is_master) ? c->run_args.num_s2m_rings : c->run_args.
+	num_m2s_rings;
+      for (i = 0; i < num; i++)
+	{
+	  mq = &c->rx_queues[i];
+	  if (mq != NULL)
+	    {
+	      if (mq->int_fd > 0)
+		{
+		  if (c->on_interrupt != NULL)
+		    lm->control_fd_update (mq->int_fd, MEMIF_FD_EVENT_DEL);
+		  close (mq->int_fd);
+		}
+	      free_list_elt (lm->interrupt_list, lm->interrupt_list_len,
+			     mq->int_fd);
+	      mq->int_fd = -1;
+	    }
+	}
+      free (c->rx_queues);
+      c->rx_queues = NULL;
+    }
+
+  if (c->regions != NULL)
+    {
+      if (munmap (c->regions[0].shm, c->regions[0].region_size) < 0)
+	return memif_syscall_error_handler (errno);
+      if (c->regions[0].fd > 0)
+	close (c->regions[0].fd);
+      c->regions[0].fd = -1;
+      free (c->regions);
+      c->regions = NULL;
+    }
+
+  memset (&c->run_args, 0, sizeof (memif_conn_run_args_t));
+
+  memif_msg_queue_free (&c->msg_queue);
+
+  if (!(c->args.is_master))
+    {
+      if (lm->disconn_slaves == 0)
+	{
+	  if (timerfd_settime (lm->timerfd, 0, &lm->arm, NULL) < 0)
+	    {
+	      err = memif_syscall_error_handler (errno);
+	      DBG_UNIX ("timerfd_settime: arm");
+	    }
+	}
+      lm->disconn_slaves++;
+    }
+
+  return err;
+}
+
+int
+memif_delete (memif_conn_handle_t * conn)
+{
+  memif_connection_t *c = (memif_connection_t *) * conn;
+  if (c == NULL)
+    {
+      DBG ("no connection");
+      return MEMIF_ERR_NOCONN;
+    }
+  libmemif_main_t *lm = &libmemif_main;
+  memif_list_elt_t *e = NULL;
+  memif_socket_t *ms = NULL;
+
+  int err = MEMIF_ERR_SUCCESS;
+
+  if (c->fd > 0)
+    {
+      DBG ("DISCONNECTING");
+      err = memif_disconnect_internal (c);
+      if (err == MEMIF_ERR_NOCONN)
+	return err;
+    }
+
+  free_list_elt_ctx (lm->control_list, lm->control_list_len, c);
+
+  if (c->args.is_master)
+    {
+      get_list_elt (&e, lm->listener_list, lm->listener_list_len,
+		    c->listener_fd);
+      if (e != NULL)
+	{
+	  ms = (memif_socket_t *) e->data_struct;
+	  ms->use_count--;
+	  free_list_elt (ms->interface_list, ms->interface_list_len,
+			 c->args.interface_id);
+	  if (ms->use_count <= 0)
+	    {
+	      lm->control_fd_update (c->listener_fd, MEMIF_FD_EVENT_DEL);
+	      free_list_elt (lm->listener_list, lm->listener_list_len,
+			     c->listener_fd);
+	      close (c->listener_fd);
+	      c->listener_fd = ms->fd = -1;
+	      free (ms->interface_list);
+	      ms->interface_list = NULL;
+	      free (ms->filename);
+	      ms->filename = NULL;
+	      free (ms);
+	      ms = NULL;
+	    }
+	}
+    }
+  else
+    {
+      lm->disconn_slaves--;
+      if (lm->disconn_slaves <= 0)
+	{
+	  if (timerfd_settime (lm->timerfd, 0, &lm->disarm, NULL) < 0)
+	    {
+	      err = memif_syscall_error_handler (errno);
+	      DBG ("timerfd_settime: disarm");
+	    }
+	}
+    }
+
+  if (c->args.socket_filename)
+    free (c->args.socket_filename);
+  c->args.socket_filename = NULL;
+
+  free (c);
+  c = NULL;
+
+  *conn = c;
+  return err;
+}
+
+int
+memif_connect1 (memif_connection_t * c)
+{
+  libmemif_main_t *lm = &libmemif_main;
+  memif_region_t *mr = c->regions;
+  memif_queue_t *mq;
+  int i;
+  uint16_t num;
+
+  if (mr != NULL)
+    {
+      if (!mr->shm)
+	{
+	  if (mr->fd < 0)
+	    return MEMIF_ERR_NO_SHMFD;
+
+	  if ((mr->shm = mmap (NULL, mr->region_size, PROT_READ | PROT_WRITE,
+			       MAP_SHARED, mr->fd, 0)) == MAP_FAILED)
+	    {
+	      return memif_syscall_error_handler (errno);
+	    }
+	}
+    }
+
+  num =
+    (c->args.is_master) ? c->run_args.num_m2s_rings : c->run_args.
+    num_s2m_rings;
+  for (i = 0; i < num; i++)
+    {
+      mq = &c->tx_queues[i];
+      if (mq != NULL)
+	{
+	  mq->ring = c->regions[mq->region].shm + mq->offset;
+	  if (mq->ring->cookie != MEMIF_COOKIE)
+	    {
+	      DBG ("wrong cookie on tx ring %u", i);
+	      return MEMIF_ERR_COOKIE;
+	    }
+	  mq->ring->head = mq->ring->tail = mq->last_head = mq->alloc_bufs =
+	    0;
+	}
+    }
+  num =
+    (c->args.is_master) ? c->run_args.num_s2m_rings : c->run_args.
+    num_m2s_rings;
+  for (i = 0; i < num; i++)
+    {
+      mq = &c->rx_queues[i];
+      if (mq != NULL)
+	{
+	  mq->ring = c->regions[mq->region].shm + mq->offset;
+	  if (mq->ring->cookie != MEMIF_COOKIE)
+	    {
+	      DBG ("wrong cookie on rx ring %u", i);
+	      return MEMIF_ERR_COOKIE;
+	    }
+	  mq->ring->head = mq->ring->tail = mq->last_head = mq->alloc_bufs =
+	    0;
+	}
+    }
+
+  lm->control_fd_update (c->fd, MEMIF_FD_EVENT_READ | MEMIF_FD_EVENT_MOD);
+
+  return 0;
+}
+
+int
+memif_init_regions_and_queues (memif_connection_t * conn)
+{
+  memif_ring_t *ring = NULL;
+  uint64_t buffer_offset;
+  memif_region_t *r;
+  int i, j;
+  libmemif_main_t *lm = &libmemif_main;
+  memif_list_elt_t e;
+
+  conn->regions = (memif_region_t *) malloc (sizeof (memif_region_t));
+  if (conn->regions == NULL)
+    return memif_syscall_error_handler (errno);
+  r = conn->regions;
+
+  buffer_offset =
+    (conn->run_args.num_s2m_rings +
+     conn->run_args.num_m2s_rings) * (sizeof (memif_ring_t) +
+				      sizeof (memif_desc_t) *
+				      (1 << conn->run_args.log2_ring_size));
+
+  r->region_size = buffer_offset +
+    conn->run_args.buffer_size * (1 << conn->run_args.log2_ring_size) *
+    (conn->run_args.num_s2m_rings + conn->run_args.num_m2s_rings);
+
+  if ((r->fd = memfd_create ("memif region 0", MFD_ALLOW_SEALING)) == -1)
+    return memif_syscall_error_handler (errno);
+/*
+    if ((fcntl (r->fd, F_ADD_SEALS, F_SEAL_SHRINK)) == -1)
+        return memif_syscall_error_handler (errno);
+*/
+  if ((ftruncate (r->fd, r->region_size)) == -1)
+    return memif_syscall_error_handler (errno);
+
+  if ((r->shm = mmap (NULL, r->region_size, PROT_READ | PROT_WRITE,
+		      MAP_SHARED, r->fd, 0)) == MAP_FAILED)
+    return memif_syscall_error_handler (errno);
+
+  for (i = 0; i < conn->run_args.num_s2m_rings; i++)
+    {
+      ring = memif_get_ring (conn, MEMIF_RING_S2M, i);
+      DBG ("RING: %p I: %d", ring, i);
+      ring->head = ring->tail = 0;
+      ring->cookie = MEMIF_COOKIE;
+      ring->flags = 0;
+      for (j = 0; j < (1 << conn->run_args.log2_ring_size); j++)
+	{
+	  uint16_t slot = i * (1 << conn->run_args.log2_ring_size) + j;
+	  ring->desc[j].region = 0;
+	  ring->desc[j].offset = buffer_offset +
+	    (uint32_t) (slot * conn->run_args.buffer_size);
+	  ring->desc[j].buffer_length = conn->run_args.buffer_size;
+	}
+    }
+  for (i = 0; i < conn->run_args.num_m2s_rings; i++)
+    {
+      ring = memif_get_ring (conn, MEMIF_RING_M2S, i);
+      DBG ("RING: %p I: %d", ring, i);
+      ring->head = ring->tail = 0;
+      ring->cookie = MEMIF_COOKIE;
+      ring->flags = 0;
+      for (j = 0; j < (1 << conn->run_args.log2_ring_size); j++)
+	{
+	  uint16_t slot =
+	    (i +
+	     conn->run_args.num_s2m_rings) *
+	    (1 << conn->run_args.log2_ring_size) + j;
+	  ring->desc[j].region = 0;
+	  ring->desc[j].offset = buffer_offset +
+	    (uint32_t) (slot * conn->run_args.buffer_size);
+	  ring->desc[j].buffer_length = conn->run_args.buffer_size;
+	}
+    }
+  memif_queue_t *mq;
+  mq =
+    (memif_queue_t *) malloc (sizeof (memif_queue_t) *
+			      conn->run_args.num_s2m_rings);
+  if (mq == NULL)
+    return memif_syscall_error_handler (errno);
+  int x;
+  for (x = 0; x < conn->run_args.num_s2m_rings; x++)
+    {
+      if ((mq[x].int_fd = eventfd (0, EFD_NONBLOCK)) < 0)
+	return memif_syscall_error_handler (errno);
+      /* add int fd to interrupt fd list */
+      e.key = mq[x].int_fd;
+      e.data_struct = conn;
+      add_list_elt (&e, &lm->interrupt_list, &lm->interrupt_list_len);
+
+      mq[x].ring = memif_get_ring (conn, MEMIF_RING_S2M, x);
+      DBG ("RING: %p I: %d", mq[x].ring, x);
+      mq[x].log2_ring_size = conn->run_args.log2_ring_size;
+      mq[x].region = 0;
+      mq[x].offset =
+	(void *) mq[x].ring - (void *) conn->regions[mq->region].shm;
+      mq[x].last_head = 0;
+      mq[x].alloc_bufs = 0;
+    }
+  conn->tx_queues = mq;
+
+  mq =
+    (memif_queue_t *) malloc (sizeof (memif_queue_t) *
+			      conn->run_args.num_m2s_rings);
+  if (mq == NULL)
+    return memif_syscall_error_handler (errno);
+  for (x = 0; x < conn->run_args.num_m2s_rings; x++)
+    {
+      if ((mq[x].int_fd = eventfd (0, EFD_NONBLOCK)) < 0)
+	return memif_syscall_error_handler (errno);
+      /* add int fd to interrupt fd list */
+      e.key = mq[x].int_fd;
+      e.data_struct = conn;
+      add_list_elt (&e, &lm->interrupt_list, &lm->interrupt_list_len);
+
+      mq[x].ring = memif_get_ring (conn, MEMIF_RING_M2S, x);
+      DBG ("RING: %p I: %d", mq[x].ring, x);
+      mq[x].log2_ring_size = conn->run_args.log2_ring_size;
+      mq[x].region = 0;
+      mq[x].offset =
+	(void *) mq[x].ring - (void *) conn->regions[mq->region].shm;
+      mq[x].last_head = 0;
+      mq[x].alloc_bufs = 0;
+    }
+  conn->rx_queues = mq;
+
+  return 0;
+}
+
+int
+memif_buffer_alloc (memif_conn_handle_t conn, uint16_t qid,
+		    memif_buffer_t * bufs, uint16_t count,
+		    uint16_t * count_out)
+{
+  memif_connection_t *c = (memif_connection_t *) conn;
+  if (c == NULL)
+    return MEMIF_ERR_NOCONN;
+  if (c->fd < 0)
+    return MEMIF_ERR_DISCONNECTED;
+  uint8_t num =
+    (c->args.is_master) ? c->run_args.num_m2s_rings : c->run_args.
+    num_s2m_rings;
+  if (qid >= num)
+    return MEMIF_ERR_QID;
+  memif_queue_t *mq = &c->tx_queues[qid];
+  memif_ring_t *ring = mq->ring;
+  memif_buffer_t *b0, *b1;
+  uint16_t mask = (1 << mq->log2_ring_size) - 1;
+  uint16_t s0, s1, ns;
+  *count_out = 0;
+  int err = MEMIF_ERR_SUCCESS;	/* 0 */
+
+  if (ring->tail != ring->head)
+    {
+      if (ring->head > ring->tail)
+	ns = (1 << mq->log2_ring_size) - ring->head + ring->tail;
+      else
+	ns = ring->tail - ring->head;
+    }
+  else
+    ns = (1 << mq->log2_ring_size);
+
+  /* (head == tail) ? receive function will asume that no packets are available */
+  ns -= 1;
+
+  while (count && ns)
+    {
+      while ((count > 2) && (ns > 2))
+	{
+	  s0 = (ring->head + mq->alloc_bufs + *count_out) & mask;
+	  s1 = (ring->head + mq->alloc_bufs + *count_out + 1) & mask;
+
+	  b0 = (bufs + *count_out);
+	  b1 = (bufs + *count_out + 1);
+
+	  b0->desc_index = s0;
+	  b1->desc_index = s1;
+	  b0->buffer_len = ring->desc[s0].buffer_length;
+	  b1->buffer_len = ring->desc[s1].buffer_length;
+	  /* TODO: support multiple regions -> ring descriptor contains region index */
+	  b0->data = c->regions->shm + ring->desc[s0].offset;
+	  b1->data = c->regions->shm + ring->desc[s1].offset;
+
+	  DBG ("allocated ring slots %u, %u", s0, s1);
+	  count -= 2;
+	  ns -= 2;
+	  *count_out += 2;
+	}
+      s0 = (ring->head + mq->alloc_bufs + *count_out) & mask;
+
+      b0 = (bufs + *count_out);
+
+      b0->desc_index = s0;
+      b0->buffer_len = ring->desc[s0].buffer_length;
+      b0->data = c->regions->shm + ring->desc[s0].offset;
+
+      DBG ("allocated ring slot %u", s0);
+      count--;
+      ns--;
+      *count_out += 1;
+    }
+
+  mq->alloc_bufs += *count_out;
+  DBG ("allocated: %u/%u bufs. Total %u allocated bufs", *count_out, count,
+       mq->alloc_bufs);
+
+  if (count)
+    {
+      DBG ("ring buffer full! qid: %u", qid);
+      err = MEMIF_ERR_NOBUF_RING;
+    }
+
+  return err;
+}
+
+int
+memif_buffer_free (memif_conn_handle_t conn, uint16_t qid,
+		   memif_buffer_t * bufs, uint16_t count,
+		   uint16_t * count_out)
+{
+  memif_connection_t *c = (memif_connection_t *) conn;
+  if (c == NULL)
+    return MEMIF_ERR_NOCONN;
+  if (c->fd < 0)
+    return MEMIF_ERR_DISCONNECTED;
+  uint8_t num =
+    (c->args.is_master) ? c->run_args.num_s2m_rings : c->run_args.
+    num_m2s_rings;
+  if (qid >= num)
+    return MEMIF_ERR_QID;
+  libmemif_main_t *lm = &libmemif_main;
+  memif_queue_t *mq = &c->rx_queues[qid];
+  memif_ring_t *ring = mq->ring;
+  uint16_t tail = ring->tail;
+  uint16_t mask = (1 << mq->log2_ring_size) - 1;
+  memif_buffer_t *b0, *b1;
+  *count_out = 0;
+
+  if (mq->alloc_bufs < count)
+    count = mq->alloc_bufs;
+
+  while (count)
+    {
+      while (count > 2)
+	{
+	  b0 = (bufs + *count_out);
+	  b1 = (bufs + *count_out + 1);
+	  tail = (b0->desc_index + 1) & mask;
+	  tail = (b1->desc_index + 1) & mask;
+	  b0->data = NULL;
+	  b1->data = NULL;
+
+	  count -= 2;
+	  *count_out += 2;
+	  mq->alloc_bufs -= 2;
+	}
+      b0 = (bufs + *count_out);
+      tail = (b0->desc_index + 1) & mask;
+      b0->data = NULL;
+
+      count--;
+      *count_out += 1;
+      mq->alloc_bufs--;
+    }
+  MEMIF_MEORY_BARRIER ();
+  ring->tail = tail;
+
+  return MEMIF_ERR_SUCCESS;	/* 0 */
+}
+
+int
+memif_tx_burst (memif_conn_handle_t conn, uint16_t qid,
+		memif_buffer_t * bufs, uint16_t count, uint16_t * tx)
+{
+  memif_connection_t *c = (memif_connection_t *) conn;
+  if (c == NULL)
+    return MEMIF_ERR_NOCONN;
+  if (c->fd < 0)
+    return MEMIF_ERR_DISCONNECTED;
+  uint8_t num =
+    (c->args.is_master) ? c->run_args.num_m2s_rings : c->run_args.
+    num_s2m_rings;
+  if (qid >= num)
+    return MEMIF_ERR_QID;
+  memif_queue_t *mq = &c->tx_queues[qid];
+  memif_ring_t *ring = mq->ring;
+  uint16_t head = ring->head;
+  uint16_t mask = (1 << mq->log2_ring_size) - 1;
+  *tx = 0;
+  memif_buffer_t *b0, *b1;
+
+  while (count)
+    {
+      while (count > 2)
+	{
+	  b0 = (bufs + *tx);
+	  b1 = (bufs + *tx + 1);
+	  ring->desc[b0->desc_index].length = b0->data_len;
+	  ring->desc[b1->desc_index].length = b1->data_len;
+
+#ifdef MEMIF_DBG_SHM
+	  print_bytes (b0->data, b0->data_len, DBG_TX_BUF);
+	  print_bytes (b1->data, b1->data_len, DBG_TX_BUF);
+#endif
+
+	  head = (b0->desc_index + 1) & mask;
+	  head = (b1->desc_index + 1) & mask;
+
+	  b0->data = NULL;
+	  b0->data_len = 0;
+	  b1->data = NULL;
+	  b1->data_len = 0;
+
+	  count -= 2;
+	  *tx += 2;
+	}
+
+      b0 = (bufs + *tx);
+      ring->desc[b0->desc_index].length = b0->data_len;
+
+#ifdef MEMIF_DBG_SHM
+      print_bytes (b0->data, b0->data_len, DBG_TX_BUF);
+#endif
+
+      head = (b0->desc_index + 1) & mask;
+
+      b0->data = NULL;
+      b0->data_len = 0;
+
+      count--;
+      *tx += 1;
+    }
+  MEMIF_MEORY_BARRIER ();
+  ring->head = head;
+
+  mq->alloc_bufs -= *tx;
+
+  if ((ring->flags & MEMIF_RING_FLAG_MASK_INT) == 0)
+    {
+      uint64_t a = 1;
+      int r = write (mq->int_fd, &a, sizeof (a));
+      if (r < 0)
+	return MEMIF_ERR_INT_WRITE;
+    }
+
+  return MEMIF_ERR_SUCCESS;	/* 0 */
+}
+
+int
+memif_rx_burst (memif_conn_handle_t conn, uint16_t qid,
+		memif_buffer_t * bufs, uint16_t count, uint16_t * rx)
+{
+  memif_connection_t *c = (memif_connection_t *) conn;
+  if (c == NULL)
+    return MEMIF_ERR_NOCONN;
+  if (c->fd < 0)
+    return MEMIF_ERR_DISCONNECTED;
+  uint8_t num =
+    (c->args.is_master) ? c->run_args.num_s2m_rings : c->run_args.
+    num_m2s_rings;
+  if (qid >= num)
+    return MEMIF_ERR_QID;
+  memif_queue_t *mq = &c->rx_queues[qid];
+  memif_ring_t *ring = mq->ring;
+  uint16_t head = ring->head;
+  uint16_t ns;
+  uint16_t mask = (1 << mq->log2_ring_size) - 1;
+  memif_buffer_t *b0, *b1;
+  *rx = 0;
+
+  uint64_t b;
+  ssize_t r = read (mq->int_fd, &b, sizeof (b));
+  if ((r == -1) && (errno != EAGAIN))
+    return memif_syscall_error_handler (errno);
+
+  if (head == mq->last_head)
+    return 0;
+
+  if (head > mq->last_head)
+    ns = head - mq->last_head;
+  else
+    ns = (1 << mq->log2_ring_size) - mq->last_head + head;
+
+  while (ns && count)
+    {
+      while ((ns > 2) && (count > 2))
+	{
+	  b0 = (bufs + *rx);
+	  b1 = (bufs + *rx + 1);
+
+	  b0->desc_index = mq->last_head;
+	  b1->desc_index = mq->last_head + 1;
+	  b0->data = memif_get_buffer (conn, ring, mq->last_head);
+	  b1->data = memif_get_buffer (conn, ring, mq->last_head + 1);
+	  b0->data_len = ring->desc[mq->last_head].length;
+	  b1->data_len = ring->desc[mq->last_head + 1].length;
+	  b0->buffer_len = ring->desc[mq->last_head].buffer_length;
+	  b1->buffer_len = ring->desc[mq->last_head + 1].buffer_length;
+
+#ifdef MEMIF_DBG_SHM
+	  print_bytes (b0->data, b0->data_len, DBG_RX_BUF);
+	  print_bytes (b1->data, b1->data_len, DBG_RX_BUF);
+#endif
+
+	  mq->last_head = (mq->last_head + 2) & mask;
+
+	  ns -= 2;
+	  count -= 2;
+	  *rx += 2;
+	}
+      b0 = (bufs + *rx);
+
+      b0->desc_index = mq->last_head;
+      b0->data = memif_get_buffer (conn, ring, mq->last_head);
+      b0->data_len = ring->desc[mq->last_head].length;
+      b0->buffer_len = ring->desc[mq->last_head].buffer_length;
+
+#ifdef MEMIF_DBG_SHM
+      print_bytes (b0->data, b0->data_len, DBG_RX_BUF);
+#endif
+
+      mq->last_head = (mq->last_head + 1) & mask;
+
+      ns--;
+      count--;
+      *rx += 1;
+    }
+
+  mq->alloc_bufs += *rx;
+
+  if (ns)
+    {
+      DBG ("not enough buffers!");
+      return MEMIF_ERR_NOBUF;
+    }
+
+  return MEMIF_ERR_SUCCESS;	/* 0 */
+}
+
+int
+memif_get_details (memif_conn_handle_t conn, memif_details_t * md,
+		   char *buf, ssize_t buflen)
+{
+  memif_connection_t *c = (memif_connection_t *) conn;
+  if (c == NULL)
+    return MEMIF_ERR_NOCONN;
+
+  int err = MEMIF_ERR_SUCCESS, i;
+  ssize_t l0, l1, total_l;
+  l0 = 0;
+
+  l1 = strlen ((char *) c->args.interface_name);
+  if (l0 + l1 <= buflen)
+    {
+      md->if_name = strncpy (buf + l0, (char *) c->args.interface_name, l1);
+      md->if_name[l0 + l1] = '\0';
+      l0 += l1 + 1;
+    }
+  else
+    err = MEMIF_ERR_NOBUF_DET;
+
+  l1 = strlen ((char *) c->args.instance_name);
+  if (l0 + l1 <= buflen)
+    {
+      md->inst_name = strncpy (buf + l0, (char *) c->args.instance_name, l1);
+      md->inst_name[l0 + l1] = '\0';
+      l0 += l1 + 1;
+    }
+  else
+    err = MEMIF_ERR_NOBUF_DET;
+
+  l1 = strlen ((char *) c->remote_if_name);
+  if (l0 + l1 <= buflen)
+    {
+      md->remote_if_name = strncpy (buf + l0, (char *) c->remote_if_name, l1);
+      md->remote_if_name[l0 + l1] = '\0';
+      l0 += l1 + 1;
+    }
+  else
+    err = MEMIF_ERR_NOBUF_DET;
+
+  l1 = strlen ((char *) c->remote_name);
+  if (l0 + l1 <= buflen)
+    {
+      md->remote_inst_name = strncpy (buf + l0, (char *) c->remote_name, l1);
+      md->remote_inst_name[l0 + l1] = '\0';
+      l0 += l1 + 1;
+    }
+  else
+    err = MEMIF_ERR_NOBUF_DET;
+
+  md->id = c->args.interface_id;
+
+  if (c->args.secret)
+    {
+      l1 = strlen ((char *) c->args.secret);
+      md->secret = strncpy (buf + l0, (char *) c->args.secret, l1);
+      md->secret[l0 + l1] = '\0';
+      l0 += l1 + 1;
+    }
+  else
+    err = MEMIF_ERR_NOBUF_DET;
+
+  md->role = (c->args.is_master) ? 0 : 1;
+  md->mode = c->args.mode;
+
+  l1 = strlen ((char *) c->args.socket_filename);
+  if (l0 + l1 <= buflen)
+    {
+      md->socket_filename =
+	strncpy (buf + l0, (char *) c->args.socket_filename, l1);
+      md->socket_filename[l0 + l1] = '\0';
+      l0 += l1 + 1;
+    }
+  else
+    err = MEMIF_ERR_NOBUF_DET;
+
+  md->rx_queues_num =
+    (c->args.is_master) ? c->run_args.num_s2m_rings : c->run_args.
+    num_m2s_rings;
+
+  l1 = sizeof (memif_queue_details_t) * md->rx_queues_num;
+  if (l0 + l1 <= buflen)
+    {
+      md->rx_queues = (memif_queue_details_t *) buf + l0;
+      l0 = l1 + 1;
+    }
+  else
+    err = MEMIF_ERR_NOBUF_DET;
+
+  for (i = 0; i < md->rx_queues_num; i++)
+    {
+      md->rx_queues[i].qid = i;
+      md->rx_queues[i].ring_size = (1 << c->rx_queues[i].log2_ring_size);
+      md->rx_queues[i].buffer_size = c->run_args.buffer_size;
+    }
+
+  md->tx_queues_num =
+    (c->args.is_master) ? c->run_args.num_m2s_rings : c->run_args.
+    num_s2m_rings;
+
+  l1 = sizeof (memif_queue_details_t) * md->tx_queues_num;
+  if (l0 + l1 <= buflen)
+    {
+      md->tx_queues = (memif_queue_details_t *) buf + l0;
+      l0 = l1 + 1;
+    }
+  else
+    err = MEMIF_ERR_NOBUF_DET;
+
+  for (i = 0; i < md->tx_queues_num; i++)
+    {
+      md->tx_queues[i].qid = i;
+      md->tx_queues[i].ring_size = (1 << c->tx_queues[i].log2_ring_size);
+      md->tx_queues[i].buffer_size = c->run_args.buffer_size;
+    }
+
+  md->link_up_down = (c->fd > 0) ? 1 : 0;
+
+  return err;			/* 0 */
+}
+
+int
+memif_get_queue_efd (memif_conn_handle_t conn, uint16_t qid, int *efd)
+{
+  memif_connection_t *c = (memif_connection_t *) conn;
+  *efd = -1;
+  if (c == NULL)
+    return MEMIF_ERR_NOCONN;
+  if (c->fd < 0)
+    return MEMIF_ERR_DISCONNECTED;
+  uint8_t num =
+    (c->args.is_master) ? c->run_args.num_s2m_rings : c->run_args.
+    num_m2s_rings;
+  if (qid >= num)
+    return MEMIF_ERR_QID;
+
+  *efd = c->rx_queues[qid].int_fd;
+
+  return MEMIF_ERR_SUCCESS;
+}
+
+int
+memif_cleanup ()
+{
+  libmemif_main_t *lm = &libmemif_main;
+  if (lm->app_name)
+    free (lm->app_name);
+  lm->app_name = NULL;
+  if (lm->control_list)
+    free (lm->control_list);
+  lm->control_list = NULL;
+  if (lm->interrupt_list)
+    free (lm->interrupt_list);
+  lm->interrupt_list = NULL;
+  if (lm->listener_list)
+    free (lm->listener_list);
+  lm->listener_list = NULL;
+  if (lm->pending_list)
+    free (lm->pending_list);
+  lm->pending_list = NULL;
+
+  return MEMIF_ERR_SUCCESS;	/* 0 */
+}
diff --git a/extras/libmemif/src/memif.h b/extras/libmemif/src/memif.h
new file mode 100644
index 00000000000..11918eabcde
--- /dev/null
+++ b/extras/libmemif/src/memif.h
@@ -0,0 +1,185 @@
+/*
+ *------------------------------------------------------------------
+ * 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.
+ *------------------------------------------------------------------
+ */
+
+#ifndef _MEMIF_H_
+#define _MEMIF_H_
+
+#ifndef MEMIF_CACHELINE_SIZE
+#define MEMIF_CACHELINE_SIZE 64
+#endif
+
+#define MEMIF_COOKIE		0x3E31F10
+#define MEMIF_VERSION_MAJOR	1
+#define MEMIF_VERSION_MINOR	0
+#define MEMIF_VERSION		((MEMIF_VERSION_MAJOR << 8) | MEMIF_VERSION_MINOR)
+
+/*
+ *  Type definitions
+ */
+
+typedef enum memif_msg_type
+{
+  MEMIF_MSG_TYPE_NONE = 0,
+  MEMIF_MSG_TYPE_ACK = 1,
+  MEMIF_MSG_TYPE_HELLO = 2,
+  MEMIF_MSG_TYPE_INIT = 3,
+  MEMIF_MSG_TYPE_ADD_REGION = 4,
+  MEMIF_MSG_TYPE_ADD_RING = 5,
+  MEMIF_MSG_TYPE_CONNECT = 6,
+  MEMIF_MSG_TYPE_CONNECTED = 7,
+  MEMIF_MSG_TYPE_DISCONNECT = 8,
+} memif_msg_type_t;
+
+typedef enum
+{
+  MEMIF_RING_S2M = 0,
+  MEMIF_RING_M2S = 1
+} memif_ring_type_t;
+
+typedef enum
+{
+  MEMIF_INTERFACE_MODE_ETHERNET = 0,
+  MEMIF_INTERFACE_MODE_IP = 1,
+  MEMIF_INTERFACE_MODE_PUNT_INJECT = 2,
+} memif_interface_mode_t;
+
+typedef uint16_t memif_region_index_t;
+typedef uint64_t memif_region_offset_t;
+typedef uint64_t memif_region_size_t;
+typedef uint16_t memif_ring_index_t;
+typedef uint32_t memif_interface_id_t;
+typedef uint16_t memif_version_t;
+typedef uint8_t memif_log2_ring_size_t;
+
+/*
+ *  Socket messages
+ */
+
+typedef struct __attribute__ ((packed))
+{
+  uint8_t name[32];
+  memif_version_t min_version;
+  memif_version_t max_version;
+  memif_region_index_t max_region;
+  memif_ring_index_t max_m2s_ring;
+  memif_ring_index_t max_s2m_ring;
+  memif_log2_ring_size_t max_log2_ring_size;
+} memif_msg_hello_t;
+
+typedef struct __attribute__ ((packed))
+{
+  memif_version_t version;
+  memif_interface_id_t id;
+  memif_interface_mode_t mode:8;
+  uint8_t secret[24];
+  uint8_t name[32];
+} memif_msg_init_t;
+
+typedef struct __attribute__ ((packed))
+{
+  memif_region_index_t index;
+  memif_region_size_t size;
+} memif_msg_add_region_t;
+
+typedef struct __attribute__ ((packed))
+{
+  uint16_t flags;
+#define MEMIF_MSG_ADD_RING_FLAG_S2M	(1 << 0)
+  memif_ring_index_t index;
+  memif_region_index_t region;
+  memif_region_offset_t offset;
+  memif_log2_ring_size_t log2_ring_size;
+} memif_msg_add_ring_t;
+
+typedef struct __attribute__ ((packed))
+{
+  uint8_t if_name[32];
+} memif_msg_connect_t;
+
+typedef struct __attribute__ ((packed))
+{
+  uint8_t if_name[32];
+} memif_msg_connected_t;
+
+typedef struct __attribute__ ((packed))
+{
+  uint32_t code;
+  uint8_t string[96];
+} memif_msg_disconnect_t;
+
+typedef struct __attribute__ ((packed, aligned (128)))
+{
+  memif_msg_type_t type:16;
+  union
+  {
+    memif_msg_hello_t hello;
+    memif_msg_init_t init;
+    memif_msg_add_region_t add_region;
+    memif_msg_add_ring_t add_ring;
+    memif_msg_connect_t connect;
+    memif_msg_connected_t connected;
+    memif_msg_disconnect_t disconnect;
+  };
+} memif_msg_t;
+
+_Static_assert (sizeof (memif_msg_t) == 128,
+		"Size of memif_msg_t must be 128");
+
+/*
+ *  Ring and Descriptor Layout
+ */
+
+typedef struct __attribute__ ((packed))
+{
+  uint16_t flags;
+#define MEMIF_DESC_FLAG_NEXT (1 << 0)
+  memif_region_index_t region;
+  uint32_t buffer_length;
+  uint32_t length;
+  uint8_t reserved[4];
+  memif_region_offset_t offset;
+  uint64_t metadata;
+} memif_desc_t;
+
+_Static_assert (sizeof (memif_desc_t) == 32,
+		"Size of memif_dsct_t must be 32");
+
+#define MEMIF_CACHELINE_ALIGN_MARK(mark) \
+  uint8_t mark[0] __attribute__((aligned(MEMIF_CACHELINE_SIZE)))
+
+typedef struct
+{
+  MEMIF_CACHELINE_ALIGN_MARK (cacheline0);
+  uint32_t cookie;
+  uint16_t flags;
+#define MEMIF_RING_FLAG_MASK_INT 1
+  volatile uint16_t head;
+    MEMIF_CACHELINE_ALIGN_MARK (cacheline1);
+  volatile uint16_t tail;
+    MEMIF_CACHELINE_ALIGN_MARK (cacheline2);
+  memif_desc_t desc[0];
+} memif_ring_t;
+
+#endif /* _MEMIF_H_ */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/extras/libmemif/src/memif_private.h b/extras/libmemif/src/memif_private.h
new file mode 100644
index 00000000000..51f3be662fb
--- /dev/null
+++ b/extras/libmemif/src/memif_private.h
@@ -0,0 +1,265 @@
+/*
+ *------------------------------------------------------------------
+ * 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.
+ *------------------------------------------------------------------
+ */
+
+
+#ifndef _MEMIF_PRIVATE_H_
+#define _MEMIF_PRIVATE_H_
+
+#define _GNU_SOURCE
+#include <unistd.h>
+#include <sys/syscall.h>
+#include <stdint.h>
+#include <inttypes.h>
+#include <limits.h>
+#include <sys/timerfd.h>
+
+#include <libmemif.h>
+
+#define MEMIF_DEFAULT_SOCKET_DIR "/run/vpp"
+#define MEMIF_DEFAULT_SOCKET_FILENAME  "memif.sock"
+#define MEMIF_DEFAULT_RING_SIZE 1024
+#define MEMIF_DEFAULT_LOG2_RING_SIZE 10
+#define MEMIF_DEFAULT_RX_QUEUES 1
+#define MEMIF_DEFAULT_TX_QUEUES 1
+#define MEMIF_DEFAULT_BUFFER_SIZE 2048
+
+#define MEMIF_MAX_M2S_RING		255
+#define MEMIF_MAX_S2M_RING		255
+#define MEMIF_MAX_REGION		255
+#define MEMIF_MAX_LOG2_RING_SIZE	14
+
+#define MEMIF_MAX_FDS 512
+
+
+#ifdef MEMIF_DBG
+#define DBG(...) do {                                                             \
+                        printf("MEMIF_DEBUG:%s:%s:%d: ", __FILE__, __func__, __LINE__);  \
+                        printf(__VA_ARGS__);                                            \
+                        printf("\n");                                                   \
+                        } while (0)
+
+#define DBG_UNIX(...) do {                                                        \
+                      printf("MEMIF_DEBUG_UNIX:%s:%s:%d: ", __FILE__, __func__, __LINE__);  \
+                      printf(__VA_ARGS__);                                    \
+                      printf("\n");                                           \
+                      } while (0)
+
+#define error_return_unix(...) do {                                             \
+                                DBG_UNIX(__VA_ARGS__);                          \
+                                return -1;                                      \
+                                } while (0)
+#define error_return(...) do {                                                  \
+                            DBG(__VA_ARGS__);                                   \
+                            return -1;                                          \
+                            } while (0)
+#else
+#define DBG(...)
+#define DBG_UNIX(...)
+#define error_return_unix(...) do {                                             \
+                                return -1;                                      \
+                                } while (0)
+#define error_return(...) do {                                                  \
+                            return -1;                                          \
+                            } while (0)
+
+#endif /* MEMIF_DBG */
+
+typedef struct
+{
+  void *shm;
+  uint32_t region_size;
+  int fd;
+} memif_region_t;
+
+typedef struct
+{
+  memif_ring_t *ring;
+  uint8_t log2_ring_size;
+  uint8_t region;
+  uint32_t offset;
+
+  uint16_t last_head;
+  uint16_t last_tail;
+
+  int int_fd;
+
+  uint64_t int_count;
+  uint32_t alloc_bufs;
+} memif_queue_t;
+
+typedef struct memif_msg_queue_elt
+{
+  memif_msg_t msg;
+  int fd;
+  struct memif_msg_queue_elt *next;
+} memif_msg_queue_elt_t;
+
+struct memif_connection;
+
+typedef struct memif_connection memif_connection_t;
+
+/* functions called by memif_control_fd_handler */
+typedef int (memif_fn) (memif_connection_t * conn);
+
+typedef struct
+{
+  uint8_t num_s2m_rings;
+  uint8_t num_m2s_rings;
+  uint16_t buffer_size;
+  memif_log2_ring_size_t log2_ring_size;
+} memif_conn_run_args_t;
+
+typedef struct memif_connection
+{
+  uint16_t index;
+  memif_conn_args_t args;
+  memif_conn_run_args_t run_args;
+
+  int fd;
+  int listener_fd;
+
+  memif_fn *write_fn, *read_fn, *error_fn;
+
+  memif_connection_update_t *on_connect, *on_disconnect;
+  memif_interrupt_t *on_interrupt;
+  void *private_ctx;
+
+  /* connection message queue */
+  memif_msg_queue_elt_t *msg_queue;
+
+  uint8_t remote_if_name[32];
+  uint8_t remote_name[32];
+  uint8_t remote_disconnect_string[96];
+
+  memif_region_t *regions;
+
+  memif_queue_t *rx_queues;
+  memif_queue_t *tx_queues;
+
+  uint16_t flags;
+#define MEMIF_CONNECTION_FLAG_WRITE (1 << 0)
+} memif_connection_t;
+
+/*
+ * WIP
+ */
+typedef struct
+{
+  int key;			/* fd or id */
+  void *data_struct;
+} memif_list_elt_t;
+
+/*
+ * WIP
+ */
+typedef struct
+{
+  int fd;
+  uint16_t use_count;
+  uint8_t *filename;
+  uint16_t interface_list_len;
+  memif_list_elt_t *interface_list;	/* memif master interfaces listening on this socket */
+} memif_socket_t;
+
+/*
+ * WIP
+ */
+/* probably function like memif_cleanup () will need to be called to close timerfd */
+typedef struct
+{
+  memif_control_fd_update_t *control_fd_update;
+  int timerfd;
+  struct itimerspec arm, disarm;
+  uint16_t disconn_slaves;
+  uint8_t *app_name;
+
+  /* master implementation... */
+  memif_socket_t ms;
+
+  uint16_t control_list_len;
+  uint16_t interrupt_list_len;
+  uint16_t listener_list_len;
+  uint16_t pending_list_len;
+  memif_list_elt_t *control_list;
+  memif_list_elt_t *interrupt_list;
+  memif_list_elt_t *listener_list;
+  memif_list_elt_t *pending_list;
+} libmemif_main_t;
+
+extern libmemif_main_t libmemif_main;
+extern int memif_epfd;
+
+/* main.c */
+
+/* if region doesn't contain shared memory, mmap region, check ring cookie */
+int memif_connect1 (memif_connection_t * c);
+
+/* memory map region, initalize rings and queues */
+int memif_init_regions_and_queues (memif_connection_t * c);
+
+int memif_disconnect_internal (memif_connection_t * c);
+
+/* map errno to memif error code */
+int memif_syscall_error_handler (int err_code);
+
+int add_list_elt (memif_list_elt_t * e, memif_list_elt_t ** list,
+		  uint16_t * len);
+
+int get_list_elt (memif_list_elt_t ** e, memif_list_elt_t * list,
+		  uint16_t len, int key);
+
+int free_list_elt (memif_list_elt_t * list, uint16_t len, int key);
+
+#ifndef __NR_memfd_create
+#if defined __x86_64__
+#define __NR_memfd_create 319
+#elif defined __arm__
+#define __NR_memfd_create 385
+#elif defined __aarch64__
+#define __NR_memfd_create 279
+#else
+#error "__NR_memfd_create unknown for this architecture"
+#endif
+#endif
+
+static inline int
+memfd_create (const char *name, unsigned int flags)
+{
+  return syscall (__NR_memfd_create, name, flags);
+}
+
+static inline void *
+memif_get_buffer (memif_connection_t * conn, memif_ring_t * ring,
+		  uint16_t index)
+{
+  return (conn->regions[ring->desc[index].region].shm +
+	  ring->desc[index].offset);
+}
+
+#ifndef F_LINUX_SPECIFIC_BASE
+#define F_LINUX_SPECIFIC_BASE 1024
+#endif
+#define MFD_ALLOW_SEALING       0x0002U
+#define F_ADD_SEALS (F_LINUX_SPECIFIC_BASE + 9)
+#define F_GET_SEALS (F_LINUX_SPECIFIC_BASE + 10)
+
+#define F_SEAL_SEAL     0x0001	/* prevent further seals from being set */
+#define F_SEAL_SHRINK   0x0002	/* prevent file from shrinking */
+#define F_SEAL_GROW     0x0004	/* prevent file from growing */
+#define F_SEAL_WRITE    0x0008	/* prevent writes */
+
+#endif /* _MEMIF_PRIVATE_H_ */
diff --git a/extras/libmemif/src/socket.c b/extras/libmemif/src/socket.c
new file mode 100644
index 00000000000..9c9b3a8dd73
--- /dev/null
+++ b/extras/libmemif/src/socket.c
@@ -0,0 +1,883 @@
+/*
+ *------------------------------------------------------------------
+ * 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.
+ *------------------------------------------------------------------
+ */
+
+#define _GNU_SOURCE
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <sys/un.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <net/if.h>
+#include <sys/ioctl.h>
+#include <sys/uio.h>
+#include <sys/mman.h>
+#include <sys/prctl.h>
+#include <fcntl.h>
+#include <errno.h>
+
+#include <socket.h>
+#include <memif.h>
+
+#define memif_min(a,b) ((a < b) ? (a) : (b))
+
+/* sends msg to socket */
+static_fn int
+memif_msg_send (int fd, memif_msg_t * msg, int afd)
+{
+  struct msghdr mh = { 0 };
+  struct iovec iov[1];
+  char ctl[CMSG_SPACE (sizeof (int))];
+  int rv, err = MEMIF_ERR_SUCCESS;	/* 0 */
+
+  iov[0].iov_base = (void *) msg;
+  iov[0].iov_len = sizeof (memif_msg_t);
+  mh.msg_iov = iov;
+  mh.msg_iovlen = 1;
+
+  if (afd > 0)
+    {
+      struct cmsghdr *cmsg;
+      memset (&ctl, 0, sizeof (ctl));
+      mh.msg_control = ctl;
+      mh.msg_controllen = sizeof (ctl);
+      cmsg = CMSG_FIRSTHDR (&mh);
+      cmsg->cmsg_len = CMSG_LEN (sizeof (int));
+      cmsg->cmsg_level = SOL_SOCKET;
+      cmsg->cmsg_type = SCM_RIGHTS;
+      memcpy (CMSG_DATA (cmsg), &afd, sizeof (int));
+    }
+  rv = sendmsg (fd, &mh, 0);
+  if (rv < 0)
+    err = memif_syscall_error_handler (errno);
+  DBG ("Message type %u sent", msg->type);
+  return err;
+}
+
+/* response from memif master - master is ready to handle next message */
+static_fn int
+memif_msg_enq_ack (memif_connection_t * c)
+{
+  memif_msg_queue_elt_t *e =
+    (memif_msg_queue_elt_t *) malloc (sizeof (memif_msg_queue_elt_t));
+  if (e == NULL)
+    return memif_syscall_error_handler (errno);
+
+  memset (&e->msg, 0, sizeof (e->msg));
+  e->msg.type = MEMIF_MSG_TYPE_ACK;
+  e->fd = -1;
+
+  e->next = NULL;
+  if (c->msg_queue == NULL)
+    {
+      c->msg_queue = e;
+      return MEMIF_ERR_SUCCESS;	/* 0 */
+    }
+
+  memif_msg_queue_elt_t *cur = c->msg_queue;
+  while (cur->next != NULL)
+    {
+      cur = cur->next;
+    }
+  cur->next = e;
+
+  return MEMIF_ERR_SUCCESS;	/* 0 */
+}
+
+static_fn int
+memif_msg_send_hello (int fd)
+{
+  libmemif_main_t *lm = &libmemif_main;
+  memif_msg_t msg = { 0 };
+  memif_msg_hello_t *h = &msg.hello;
+  msg.type = MEMIF_MSG_TYPE_HELLO;
+  h->min_version = MEMIF_VERSION;
+  h->max_version = MEMIF_VERSION;
+  h->max_s2m_ring = MEMIF_MAX_M2S_RING;
+  h->max_m2s_ring = MEMIF_MAX_M2S_RING;
+  h->max_region = MEMIF_MAX_REGION;
+  h->max_log2_ring_size = MEMIF_MAX_LOG2_RING_SIZE;
+
+  strncpy ((char *) h->name, lm->app_name, strlen (lm->app_name));
+
+  /* msg hello is not enqueued but sent directly,
+     because it is the first msg to be sent */
+  return memif_msg_send (fd, &msg, -1);
+}
+
+/* send id and secret (optional) for interface identification */
+static_fn int
+memif_msg_enq_init (memif_connection_t * c)
+{
+  memif_msg_queue_elt_t *e =
+    (memif_msg_queue_elt_t *) malloc (sizeof (memif_msg_queue_elt_t));
+  if (e == NULL)
+    return memif_syscall_error_handler (errno);
+  memset (e, 0, sizeof (memif_msg_queue_elt_t));
+
+  memset (&e->msg, 0, sizeof (e->msg));
+  memif_msg_init_t *i = &e->msg.init;
+
+  e->msg.type = MEMIF_MSG_TYPE_INIT;
+  e->fd = -1;
+  i->version = MEMIF_VERSION;
+  i->id = c->args.interface_id;
+  i->mode = c->args.mode;
+
+  strncpy ((char *) i->name, (char *) c->args.instance_name,
+	   strlen ((char *) c->args.instance_name));
+  if (c->args.secret)
+    strncpy ((char *) i->secret, (char *) c->args.secret, sizeof (i->secret));
+
+  e->next = NULL;
+  if (c->msg_queue == NULL)
+    {
+      c->msg_queue = e;
+      return MEMIF_ERR_SUCCESS;	/* 0 */
+    }
+
+  memif_msg_queue_elt_t *cur = c->msg_queue;
+  while (cur->next != NULL)
+    {
+      cur = cur->next;
+    }
+  cur->next = e;
+
+  return MEMIF_ERR_SUCCESS;	/* 0 */
+}
+
+/* send information about region specified by region_index */
+static_fn int
+memif_msg_enq_add_region (memif_connection_t * c, uint8_t region_index)
+{
+  /* maybe check if region is valid? */
+  memif_region_t *mr = &c->regions[region_index];
+
+  memif_msg_queue_elt_t *e =
+    (memif_msg_queue_elt_t *) malloc (sizeof (memif_msg_queue_elt_t));
+  if (e == NULL)
+    return memif_syscall_error_handler (errno);
+
+  memset (&e->msg, 0, sizeof (e->msg));
+  memif_msg_add_region_t *ar = &e->msg.add_region;
+
+  e->msg.type = MEMIF_MSG_TYPE_ADD_REGION;
+  e->fd = mr->fd;
+  ar->index = region_index;
+  ar->size = mr->region_size;
+
+  e->next = NULL;
+  if (c->msg_queue == NULL)
+    {
+      c->msg_queue = e;
+      return MEMIF_ERR_SUCCESS;	/* 0 */
+    }
+
+  memif_msg_queue_elt_t *cur = c->msg_queue;
+  while (cur->next != NULL)
+    {
+      cur = cur->next;
+    }
+  cur->next = e;
+
+  return MEMIF_ERR_SUCCESS;	/* 0 */
+}
+
+/* send information about ring specified by direction (S2M | M2S) and index */
+static_fn int
+memif_msg_enq_add_ring (memif_connection_t * c, uint8_t index, uint8_t dir)
+{
+  memif_msg_queue_elt_t *e =
+    (memif_msg_queue_elt_t *) malloc (sizeof (memif_msg_queue_elt_t));
+  if (e == NULL)
+    return memif_syscall_error_handler (errno);
+
+  memset (&e->msg, 0, sizeof (e->msg));
+  memif_msg_add_ring_t *ar = &e->msg.add_ring;
+
+  e->msg.type = MEMIF_MSG_TYPE_ADD_RING;
+
+  /* TODO: support multiple rings */
+  memif_queue_t *mq;
+  if (dir == MEMIF_RING_M2S)
+    mq = &c->rx_queues[index];
+  else
+    mq = &c->tx_queues[index];
+
+  e->fd = mq->int_fd;
+  ar->index = index;
+  ar->offset = mq->offset;
+  ar->region = mq->region;
+  ar->log2_ring_size = mq->log2_ring_size;
+  ar->flags = (dir == MEMIF_RING_S2M) ? MEMIF_MSG_ADD_RING_FLAG_S2M : 0;
+
+  e->next = NULL;
+  if (c->msg_queue == NULL)
+    {
+      c->msg_queue = e;
+      return MEMIF_ERR_SUCCESS;	/* 0 */
+    }
+
+  memif_msg_queue_elt_t *cur = c->msg_queue;
+  while (cur->next != NULL)
+    {
+      cur = cur->next;
+    }
+  cur->next = e;
+
+  return MEMIF_ERR_SUCCESS;	/* 0 */
+}
+
+/* used as connection request from slave */
+static_fn int
+memif_msg_enq_connect (memif_connection_t * c)
+{
+  memif_msg_queue_elt_t *e =
+    (memif_msg_queue_elt_t *) malloc (sizeof (memif_msg_queue_elt_t));
+  if (e == NULL)
+    return memif_syscall_error_handler (errno);
+
+  memset (&e->msg, 0, sizeof (e->msg));
+  memif_msg_connect_t *cm = &e->msg.connect;
+
+  e->msg.type = MEMIF_MSG_TYPE_CONNECT;
+  e->fd = -1;
+  strncpy ((char *) cm->if_name, (char *) c->args.interface_name,
+	   strlen ((char *) c->args.interface_name));
+
+  e->next = NULL;
+  if (c->msg_queue == NULL)
+    {
+      c->msg_queue = e;
+      return MEMIF_ERR_SUCCESS;	/* 0 */
+    }
+
+  memif_msg_queue_elt_t *cur = c->msg_queue;
+  while (cur->next != NULL)
+    {
+      cur = cur->next;
+    }
+  cur->next = e;
+
+  return MEMIF_ERR_SUCCESS;	/* 0 */
+}
+
+/* used as confirmation of connection by master */
+static_fn int
+memif_msg_enq_connected (memif_connection_t * c)
+{
+  memif_msg_queue_elt_t *e =
+    (memif_msg_queue_elt_t *) malloc (sizeof (memif_msg_queue_elt_t));
+  if (e == NULL)
+    return memif_syscall_error_handler (errno);
+
+  memset (&e->msg, 0, sizeof (e->msg));
+  memif_msg_connected_t *cm = &e->msg.connected;
+
+  e->msg.type = MEMIF_MSG_TYPE_CONNECTED;
+  e->fd = -1;
+  strncpy ((char *) cm->if_name, (char *) c->args.interface_name,
+	   strlen ((char *) c->args.interface_name));
+
+  e->next = NULL;
+  if (c->msg_queue == NULL)
+    {
+      c->msg_queue = e;
+      return MEMIF_ERR_SUCCESS;	/* 0 */
+    }
+
+  memif_msg_queue_elt_t *cur = c->msg_queue;
+  while (cur->next != NULL)
+    {
+      cur = cur->next;
+    }
+  cur->next = e;
+
+  return MEMIF_ERR_SUCCESS;	/* 0 */
+}
+
+/* immediately send disconnect msg */
+    /* specifie protocol for disconnect msg err_code
+       so that it will be compatible with VPP? (header/doc) */
+int
+memif_msg_send_disconnect (int fd, uint8_t * err_string, uint32_t err_code)
+{
+  memif_msg_t msg = { 0 };
+  memif_msg_disconnect_t *d = &msg.disconnect;
+
+  msg.type = MEMIF_MSG_TYPE_DISCONNECT;
+  d->code = err_code;
+  uint16_t l = strlen ((char *) err_string);
+  if (l > 96)
+    {
+      DBG ("Disconnect string too long. Sending first 96 characters.");
+      l = 96;
+    }
+  strncpy ((char *) d->string, (char *) err_string, l);
+
+  return memif_msg_send (fd, &msg, -1);
+}
+
+static_fn int
+memif_msg_receive_hello (memif_connection_t * c, memif_msg_t * msg)
+{
+  memif_msg_hello_t *h = &msg->hello;
+
+  if (msg->hello.min_version > MEMIF_VERSION ||
+      msg->hello.max_version < MEMIF_VERSION)
+    {
+      DBG ("incompatible protocol version");
+      return MEMIF_ERR_PROTO;
+    }
+
+  c->run_args.num_s2m_rings = memif_min (h->max_s2m_ring + 1,
+					 c->args.num_s2m_rings);
+  c->run_args.num_m2s_rings = memif_min (h->max_m2s_ring + 1,
+					 c->args.num_m2s_rings);
+  c->run_args.log2_ring_size = memif_min (h->max_log2_ring_size,
+					  c->args.log2_ring_size);
+  c->run_args.buffer_size = c->args.buffer_size;
+  strncpy ((char *) c->remote_name, (char *) h->name,
+	   strlen ((char *) h->name));
+
+  return MEMIF_ERR_SUCCESS;	/* 0 */
+}
+
+/* handle interface identification (id, secret (optional)) */
+static_fn int
+memif_msg_receive_init (memif_socket_t * ms, int fd, memif_msg_t * msg)
+{
+  memif_msg_init_t *i = &msg->init;
+  memif_list_elt_t *elt = NULL;
+  memif_list_elt_t elt2;
+  memif_connection_t *c = NULL;
+  libmemif_main_t *lm = &libmemif_main;
+  uint8_t err_string[96];
+  memset (err_string, 0, sizeof (char) * 96);
+  int err = MEMIF_ERR_SUCCESS;	/* 0 */
+  int err_disc;
+  if (i->version != MEMIF_VERSION)
+    {
+      DBG ("MEMIF_VER_ERR");
+      strncpy ((char *) err_string, MEMIF_VER_ERR, strlen (MEMIF_VER_ERR));
+      err = MEMIF_ERR_PROTO;
+      goto error;
+    }
+
+  get_list_elt (&elt, ms->interface_list, ms->interface_list_len, i->id);
+  if (elt == NULL)
+    {
+      DBG ("MEMIF_ID_ERR");
+      strncpy ((char *) err_string, MEMIF_ID_ERR, strlen (MEMIF_ID_ERR));
+      err = MEMIF_ERR_ID;
+      goto error;
+    }
+
+  c = (memif_connection_t *) elt->data_struct;
+
+  if (!(c->args.is_master))
+    {
+      DBG ("MEMIF_SLAVE_ERR");
+      strncpy ((char *) err_string, MEMIF_SLAVE_ERR,
+	       strlen (MEMIF_SLAVE_ERR));
+      err = MEMIF_ERR_ACCSLAVE;
+      goto error;
+    }
+  if (c->fd != -1)
+    {
+      DBG ("MEMIF_CONN_ERR");
+      strncpy ((char *) err_string, MEMIF_CONN_ERR, strlen (MEMIF_CONN_ERR));
+      err = MEMIF_ERR_ALRCONN;
+      goto error;
+    }
+
+  c->fd = fd;
+
+  if (i->mode != c->args.mode)
+    {
+      DBG ("MEMIF_MODE_ERR");
+      strncpy ((char *) err_string, MEMIF_MODE_ERR, strlen (MEMIF_MODE_ERR));
+      err = MEMIF_ERR_MODE;
+      goto error;
+    }
+
+  strncpy ((char *) c->remote_name, (char *) i->name,
+	   strlen ((char *) i->name));
+
+  if (c->args.secret)
+    {
+      int r;
+      if (i->secret)
+	{
+	  if (strlen ((char *) c->args.secret) != strlen ((char *) i->secret))
+	    {
+	      DBG ("MEMIF_SECRET_ERR");
+	      strncpy ((char *) err_string,
+		       MEMIF_SECRET_ERR, strlen (MEMIF_SECRET_ERR));
+	      err = MEMIF_ERR_SECRET;
+	      goto error;
+	    }
+	  r = strncmp ((char *) i->secret, (char *) c->args.secret,
+		       strlen ((char *) c->args.secret));
+	  if (r != 0)
+	    {
+	      DBG ("MEMIF_SECRET_ERR");
+	      strncpy ((char *) err_string,
+		       MEMIF_SECRET_ERR, strlen (MEMIF_SECRET_ERR));
+	      err = MEMIF_ERR_SECRET;
+	      goto error;
+	    }
+	}
+      else
+	{
+	  DBG ("MEMIF_NOSECRET_ERR");
+	  strncpy ((char *) err_string,
+		   MEMIF_NOSECRET_ERR, strlen (MEMIF_NOSECRET_ERR));
+	  err = MEMIF_ERR_NOSECRET;
+	  goto error;
+	}
+    }
+
+  c->read_fn = memif_conn_fd_read_ready;
+  c->write_fn = memif_conn_fd_write_ready;
+  c->error_fn = memif_conn_fd_error;
+
+  elt2.key = c->fd;
+  elt2.data_struct = c;
+
+  add_list_elt (&elt2, &lm->control_list, &lm->control_list_len);
+  free_list_elt (lm->pending_list, lm->pending_list_len, fd);
+
+  return err;
+
+error:
+  memif_msg_send_disconnect (fd, err_string, 0);
+  lm->control_fd_update (fd, MEMIF_FD_EVENT_DEL);
+  free_list_elt (lm->pending_list, lm->pending_list_len, fd);
+  close (fd);
+  fd = -1;
+  return err;
+}
+
+/* receive region information and add new region to connection (if possible) */
+static_fn int
+memif_msg_receive_add_region (memif_connection_t * c, memif_msg_t * msg,
+			      int fd)
+{
+  memif_msg_add_region_t *ar = &msg->add_region;
+  memif_region_t *mr;
+  if (fd < 0)
+    return MEMIF_ERR_NO_SHMFD;
+
+  if (ar->index > MEMIF_MAX_REGION)
+    return MEMIF_ERR_MAXREG;
+
+  mr =
+    (memif_region_t *) realloc (c->regions,
+				sizeof (memif_region_t) * (ar->index + 1));
+  if (mr == NULL)
+    return memif_syscall_error_handler (errno);
+  c->regions = mr;
+  c->regions[ar->index].fd = fd;
+  c->regions[ar->index].region_size = ar->size;
+  c->regions[ar->index].shm = NULL;
+
+  return MEMIF_ERR_SUCCESS;	/* 0 */
+}
+
+/* receive ring information and add new ring to connection queue
+   (based on direction S2M | M2S) */
+static_fn int
+memif_msg_receive_add_ring (memif_connection_t * c, memif_msg_t * msg, int fd)
+{
+  memif_msg_add_ring_t *ar = &msg->add_ring;
+
+  memif_queue_t *mq;
+
+  if (fd < 0)
+    return MEMIF_ERR_NO_INTFD;
+
+  if (ar->flags & MEMIF_MSG_ADD_RING_FLAG_S2M)
+    {
+      if (ar->index > MEMIF_MAX_S2M_RING)
+	return MEMIF_ERR_MAXRING;
+      if (ar->index >= c->args.num_s2m_rings)
+	return MEMIF_ERR_MAXRING;
+
+      mq =
+	(memif_queue_t *) realloc (c->rx_queues,
+				   sizeof (memif_queue_t) * (ar->index + 1));
+      if (mq == NULL)
+	return memif_syscall_error_handler (errno);
+      c->rx_queues = mq;
+      c->rx_queues[ar->index].int_fd = fd;
+      c->rx_queues[ar->index].log2_ring_size = ar->log2_ring_size;
+      c->rx_queues[ar->index].region = ar->region;
+      c->rx_queues[ar->index].offset = ar->offset;
+      c->run_args.num_s2m_rings++;
+    }
+  else
+    {
+      if (ar->index > MEMIF_MAX_M2S_RING)
+	return MEMIF_ERR_MAXRING;
+      if (ar->index >= c->args.num_m2s_rings)
+	return MEMIF_ERR_MAXRING;
+
+      mq =
+	(memif_queue_t *) realloc (c->tx_queues,
+				   sizeof (memif_queue_t) * (ar->index + 1));
+      if (mq == NULL)
+	return memif_syscall_error_handler (errno);
+      c->tx_queues = mq;
+      c->tx_queues[ar->index].int_fd = fd;
+      c->tx_queues[ar->index].log2_ring_size = ar->log2_ring_size;
+      c->tx_queues[ar->index].region = ar->region;
+      c->tx_queues[ar->index].offset = ar->offset;
+      c->run_args.num_m2s_rings++;
+    }
+
+  return MEMIF_ERR_SUCCESS;	/* 0 */
+}
+
+/* slave -> master */
+static_fn int
+memif_msg_receive_connect (memif_connection_t * c, memif_msg_t * msg)
+{
+  memif_msg_connect_t *cm = &msg->connect;
+  libmemif_main_t *lm = &libmemif_main;
+  memif_list_elt_t elt;
+
+  int err;
+  err = memif_connect1 (c);
+  if (err != MEMIF_ERR_SUCCESS)
+    return err;
+
+  strncpy ((char *) c->remote_if_name, (char *) cm->if_name,
+	   strlen ((char *) cm->if_name));
+
+  int i;
+  if (c->on_interrupt != NULL)
+    {
+      for (i = 0; i < c->run_args.num_m2s_rings; i++)
+	{
+	  elt.key = c->rx_queues[i].int_fd;
+	  elt.data_struct = c;
+	  add_list_elt (&elt, &lm->interrupt_list, &lm->interrupt_list_len);
+
+	  lm->control_fd_update (c->rx_queues[i].int_fd, MEMIF_FD_EVENT_READ);
+	}
+
+    }
+
+  c->on_connect ((void *) c, c->private_ctx);
+
+  return err;
+}
+
+/* master -> slave */
+static_fn int
+memif_msg_receive_connected (memif_connection_t * c, memif_msg_t * msg)
+{
+  memif_msg_connect_t *cm = &msg->connect;
+  libmemif_main_t *lm = &libmemif_main;
+
+  int err;
+  err = memif_connect1 (c);
+  if (err != MEMIF_ERR_SUCCESS)
+    return err;
+
+  strncpy ((char *) c->remote_if_name, (char *) cm->if_name,
+	   strlen ((char *) cm->if_name));
+
+  int i;
+  if (c->on_interrupt != NULL)
+    {
+      for (i = 0; i < c->run_args.num_s2m_rings; i++)
+	lm->control_fd_update (c->rx_queues[i].int_fd, MEMIF_FD_EVENT_READ);
+    }
+
+  c->on_connect ((void *) c, c->private_ctx);
+
+  return err;
+}
+
+static_fn int
+memif_msg_receive_disconnect (memif_connection_t * c, memif_msg_t * msg)
+{
+  memif_msg_disconnect_t *d = &msg->disconnect;
+
+  memset (c->remote_disconnect_string, 0,
+	  sizeof (c->remote_disconnect_string));
+  strncpy ((char *) c->remote_disconnect_string, (char *) d->string,
+	   strlen ((char *) d->string));
+
+  /* on returning error, handle function will call memif_disconnect () */
+  DBG ("disconnect received: %s, mode: %d",
+       c->remote_disconnect_string, c->args.mode);
+  return MEMIF_ERR_DISCONNECT;
+}
+
+static_fn int
+memif_msg_receive (int ifd)
+{
+  char ctl[CMSG_SPACE (sizeof (int)) +
+	   CMSG_SPACE (sizeof (struct ucred))] = { 0 };
+  struct msghdr mh = { 0 };
+  struct iovec iov[1];
+  memif_msg_t msg = { 0 };
+  ssize_t size;
+  int err = MEMIF_ERR_SUCCESS;	/* 0 */
+  int fd = -1;
+  int i;
+  libmemif_main_t *lm = &libmemif_main;
+  memif_connection_t *c = NULL;
+  memif_socket_t *ms = NULL;
+  memif_list_elt_t *elt = NULL;
+
+  iov[0].iov_base = (void *) &msg;
+  iov[0].iov_len = sizeof (memif_msg_t);
+  mh.msg_iov = iov;
+  mh.msg_iovlen = 1;
+  mh.msg_control = ctl;
+  mh.msg_controllen = sizeof (ctl);
+
+  DBG ("recvmsg fd %d", ifd);
+  size = recvmsg (ifd, &mh, 0);
+  DBG ("done");
+  if (size != sizeof (memif_msg_t))
+    {
+      if (size == 0)
+	return MEMIF_ERR_DISCONNECTED;
+      else
+	return MEMIF_ERR_MFMSG;
+    }
+
+  struct ucred *cr = 0;
+  struct cmsghdr *cmsg;
+
+  cmsg = CMSG_FIRSTHDR (&mh);
+  while (cmsg)
+    {
+      if (cmsg->cmsg_level == SOL_SOCKET)
+	{
+	  if (cmsg->cmsg_type == SCM_CREDENTIALS)
+	    {
+	      cr = (struct ucred *) CMSG_DATA (cmsg);
+	    }
+	  else if (cmsg->cmsg_type == SCM_RIGHTS)
+	    {
+	      int *fdp = (int *) CMSG_DATA (cmsg);
+	      fd = *fdp;
+	    }
+	}
+      cmsg = CMSG_NXTHDR (&mh, cmsg);
+    }
+
+  DBG ("Message type %u received", msg.type);
+
+  get_list_elt (&elt, lm->control_list, lm->control_list_len, ifd);
+  if (elt != NULL)
+    c = (memif_connection_t *) elt->data_struct;
+
+  switch (msg.type)
+    {
+    case MEMIF_MSG_TYPE_ACK:
+      break;
+
+    case MEMIF_MSG_TYPE_HELLO:
+      if ((err = memif_msg_receive_hello (c, &msg)) != MEMIF_ERR_SUCCESS)
+	return err;
+      if ((err = memif_init_regions_and_queues (c)) != MEMIF_ERR_SUCCESS)
+	return err;
+      if ((err = memif_msg_enq_init (c)) != MEMIF_ERR_SUCCESS)
+	return err;
+      if ((err = memif_msg_enq_add_region (c, 0)) != MEMIF_ERR_SUCCESS)
+	return err;
+      for (i = 0; i < c->run_args.num_s2m_rings; i++)
+	{
+	  if ((err =
+	       memif_msg_enq_add_ring (c, i,
+				       MEMIF_RING_S2M)) != MEMIF_ERR_SUCCESS)
+	    return err;
+	}
+      for (i = 0; i < c->run_args.num_m2s_rings; i++)
+	{
+	  if ((err =
+	       memif_msg_enq_add_ring (c, i,
+				       MEMIF_RING_M2S)) != MEMIF_ERR_SUCCESS)
+	    return err;
+	}
+      if ((err = memif_msg_enq_connect (c)) != MEMIF_ERR_SUCCESS)
+	return err;
+      break;
+
+    case MEMIF_MSG_TYPE_INIT:
+      get_list_elt (&elt, lm->pending_list, lm->pending_list_len, ifd);
+      if (elt == NULL)
+	return -1;
+      ms = (memif_socket_t *) elt->data_struct;
+      if ((err = memif_msg_receive_init (ms, ifd, &msg)) != MEMIF_ERR_SUCCESS)
+	return err;
+      /* c->remote_pid = cr->pid */
+      /* c->remote_uid = cr->uid */
+      /* c->remote_gid = cr->gid */
+      get_list_elt (&elt, lm->control_list, lm->control_list_len, ifd);
+      if (elt == NULL)
+	return -1;
+      c = (memif_connection_t *) elt->data_struct;
+      if ((err = memif_msg_enq_ack (c)) != MEMIF_ERR_SUCCESS)
+	return err;
+      break;
+
+    case MEMIF_MSG_TYPE_ADD_REGION:
+      if ((err =
+	   memif_msg_receive_add_region (c, &msg, fd)) != MEMIF_ERR_SUCCESS)
+	return err;
+      if ((err = memif_msg_enq_ack (c)) != MEMIF_ERR_SUCCESS)
+	return err;
+      break;
+
+    case MEMIF_MSG_TYPE_ADD_RING:
+      if ((err =
+	   memif_msg_receive_add_ring (c, &msg, fd)) != MEMIF_ERR_SUCCESS)
+	return err;
+      if ((err = memif_msg_enq_ack (c)) != MEMIF_ERR_SUCCESS)
+	return err;
+      break;
+
+    case MEMIF_MSG_TYPE_CONNECT:
+      if ((err = memif_msg_receive_connect (c, &msg)) != MEMIF_ERR_SUCCESS)
+	return err;
+      if ((err = memif_msg_enq_connected (c)) != MEMIF_ERR_SUCCESS)
+	return err;
+      break;
+
+    case MEMIF_MSG_TYPE_CONNECTED:
+      if ((err = memif_msg_receive_connected (c, &msg)) != MEMIF_ERR_SUCCESS)
+	return err;
+      break;
+
+    case MEMIF_MSG_TYPE_DISCONNECT:
+      if ((err = memif_msg_receive_disconnect (c, &msg)) != MEMIF_ERR_SUCCESS)
+	return err;
+      break;
+
+    default:
+      return MEMIF_ERR_UNKNOWN_MSG;;
+      break;
+    }
+
+  if (c != NULL)
+    c->flags |= MEMIF_CONNECTION_FLAG_WRITE;
+/*    libmemif_main_t *lm = &libmemif_main;
+    lm->control_fd_update (c->fd, MEMIF_FD_EVENT_READ | MEMIF_FD_EVENT_MOD); */
+  return MEMIF_ERR_SUCCESS;	/* 0 */
+}
+
+int
+memif_conn_fd_error (memif_connection_t * c)
+{
+  DBG ("connection fd error");
+  strncpy ((char *) c->remote_disconnect_string, "connection fd error", 19);
+  int err = memif_disconnect_internal (c);
+  return err;
+}
+
+/* calls memif_msg_receive to handle pending messages on socket */
+int
+memif_conn_fd_read_ready (memif_connection_t * c)
+{
+  int err;
+  err = memif_msg_receive (c->fd);
+  if (err != 0)
+    {
+      err = memif_disconnect_internal (c);
+    }
+  return err;
+}
+
+/* get msg from msg queue buffer and send it to socket */
+int
+memif_conn_fd_write_ready (memif_connection_t * c)
+{
+  int err = MEMIF_ERR_SUCCESS;	/* 0 */
+
+
+  if ((c->flags & MEMIF_CONNECTION_FLAG_WRITE) == 0)
+    goto done;
+
+  memif_msg_queue_elt_t *e = c->msg_queue;
+  if (e == NULL)
+    goto done;
+
+  c->msg_queue = c->msg_queue->next;
+
+  c->flags &= ~MEMIF_CONNECTION_FLAG_WRITE;
+/*
+    libmemif_main_t *lm = &libmemif_main;
+
+    lm->control_fd_update (c->fd,
+        MEMIF_FD_EVENT_READ | MEMIF_FD_EVENT_WRITE | MEMIF_FD_EVENT_MOD);
+*/
+  err = memif_msg_send (c->fd, &e->msg, e->fd);
+  free (e);
+  goto done;
+
+done:
+  return err;
+}
+
+int
+memif_conn_fd_accept_ready (memif_socket_t * ms)
+{
+  int addr_len;
+  struct sockaddr_un client;
+  int conn_fd;
+  libmemif_main_t *lm = &libmemif_main;
+
+  DBG ("accept called");
+
+  addr_len = sizeof (client);
+  conn_fd =
+    accept (ms->fd, (struct sockaddr *) &client, (socklen_t *) & addr_len);
+
+  if (conn_fd < 0)
+    {
+      return memif_syscall_error_handler (errno);
+    }
+  DBG ("accept fd %d", ms->fd);
+  DBG ("conn fd %d", conn_fd);
+
+  memif_list_elt_t elt;
+  elt.key = conn_fd;
+  elt.data_struct = ms;
+
+  add_list_elt (&elt, &lm->pending_list, &lm->pending_list_len);
+  lm->control_fd_update (conn_fd, MEMIF_FD_EVENT_READ | MEMIF_FD_EVENT_WRITE);
+
+  return memif_msg_send_hello (conn_fd);
+}
+
+int
+memif_read_ready (int fd)
+{
+  int err;
+  DBG ("call recv");
+  err = memif_msg_receive (fd);
+  DBG ("recv finished");
+  return err;
+}
diff --git a/extras/libmemif/src/socket.h b/extras/libmemif/src/socket.h
new file mode 100644
index 00000000000..a8e9fbce9f6
--- /dev/null
+++ b/extras/libmemif/src/socket.h
@@ -0,0 +1,89 @@
+/*
+ *------------------------------------------------------------------
+ * 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.
+ *------------------------------------------------------------------
+ */
+
+#ifndef _SOCKET_H_
+#define _SOCKET_H
+
+#include <memif_private.h>
+
+/* interface identification errors (disconnect messages)*/
+#define MEMIF_VER_ERR       "incompatible version"
+#define MEMIF_ID_ERR        "unmatched interface id"
+#define MEMIF_SLAVE_ERR     "cannot connect to salve"
+#define MEMIF_CONN_ERR      "already connected"
+#define MEMIF_MODE_ERR      "mode mismatch"
+#define MEMIF_SECRET_ERR    "incorrect secret"
+#define MEMIF_NOSECRET_ERR  "secret required"
+
+/* socket.c */
+
+int memif_conn_fd_read_ready (memif_connection_t * c);
+
+int memif_conn_fd_write_ready (memif_connection_t * c);
+
+int memif_conn_fd_error (memif_connection_t * c);
+
+int memif_conn_fd_accept_ready (memif_socket_t * ms);
+
+int memif_read_ready (int fd);
+
+int memif_msg_send_disconnect (int fd, uint8_t * err_string,
+			       uint32_t err_code);
+
+/* when compiling unit tests, compile functions without static keyword
+   and declare functions in header file */
+#ifdef MEMIF_UNIT_TEST
+#define static_fn
+
+int memif_msg_send (int fd, memif_msg_t * msg, int afd);
+
+int memif_msg_enq_ack (memif_connection_t * c);
+
+int memif_msg_send_hello (int fd);
+
+int memif_msg_enq_init (memif_connection_t * c);
+
+int memif_msg_enq_add_region (memif_connection_t * c, uint8_t region);
+
+int memif_msg_enq_add_ring (memif_connection_t * c, uint8_t index,
+			    uint8_t dir);
+
+int memif_msg_receive_hello (memif_connection_t * c, memif_msg_t * msg);
+
+int memif_msg_receive_init (memif_socket_t * ms, int fd, memif_msg_t * msg);
+
+int memif_msg_receive_add_region (memif_connection_t * c, memif_msg_t * msg,
+				  int fd);
+
+int memif_msg_receive_add_ring (memif_connection_t * c, memif_msg_t * msg,
+				int fd);
+
+int memif_msg_enq_connect (memif_connection_t * c);
+
+int memif_msg_enq_connected (memif_connection_t * c);
+
+int memif_msg_receive_connect (memif_connection_t * c, memif_msg_t * msg);
+
+int memif_msg_receive_connected (memif_connection_t * c, memif_msg_t * msg);
+
+int memif_msg_receive_disconnect (memif_connection_t * c, memif_msg_t * msg);
+
+#else
+#define static_fn static
+#endif /* MEMIF_UNIT_TEST */
+
+#endif /* _SOCKET_H_ */