VCL-LDPRELOAD: statically link vppcom into libvcl-ldpreload.so

- Move VCL & VCL-LDPRELOAD source into src/vcl
- Statically link vppcom into libvcl-ldpreload.so

Change-Id: I778300b37e8b06640d9dbc01caf297edf7a6edb7
Signed-off-by: Dave Wallace <dwallacelf@gmail.com>

1 files changed, 3443 insertions, 0 deletions

diff --git a/src/vcl/vcom_socket.c b/src/vcl/vcom_socket.c
new file mode 100644
index 00000000000..8806ebd011a
--- /dev/null
+++ b/src/vcl/vcom_socket.c
@@ -0,0 +1,3443 @@
+/*
+ * Copyright (c) 2016 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 <unistd.h>
+#include <stdio.h>
+#include <sys/uio.h>
+#include <limits.h>
+#define __need_IOV_MAX
+#include <bits/stdio_lim.h>
+#include <netinet/tcp.h>
+
+#include <vppinfra/types.h>
+#include <vppinfra/hash.h>
+#include <vppinfra/pool.h>
+
+#include <vcl/vcom_socket.h>
+#include <vcl/vcom_socket_wrapper.h>
+#include <vcl/vcom.h>
+
+#include <vcl/vppcom.h>
+
+
+/*
+ * VCOM_SOCKET Private definitions and functions.
+ */
+
+typedef struct vcom_socket_main_t_
+{
+  u8 init;
+
+  /* vcom_socket pool */
+  vcom_socket_t *vsockets;
+
+  /* Hash table for socketidx to fd mapping */
+  uword *sockidx_by_fd;
+
+  /* vcom_epoll pool */
+  vcom_epoll_t *vepolls;
+
+  /* Hash table for epollidx to epfd mapping */
+  uword *epollidx_by_epfd;
+
+
+  /* common epitem poll for all epfd */
+  /* TBD: epitem poll per epfd */
+  /* vcom_epitem pool */
+  vcom_epitem_t *vepitems;
+
+  /* Hash table for epitemidx to epfdfd mapping */
+  uword *epitemidx_by_epfdfd;
+
+  /* Hash table - key:epfd, value:vec of epitemidx */
+  uword *epitemidxs_by_epfd;
+  /* Hash table - key:fd, value:vec of epitemidx */
+  uword *epitemidxs_by_fd;
+
+} vcom_socket_main_t;
+
+vcom_socket_main_t vcom_socket_main;
+
+
+static int
+vcom_socket_open_socket (int domain, int type, int protocol)
+{
+  int rv = -1;
+
+  /* handle domains implemented by vpp */
+  switch (domain)
+    {
+    case AF_INET:
+    case AF_INET6:
+      /* get socket type and
+       * handle the socket types supported by vpp */
+      switch (type & ~(SOCK_CLOEXEC | SOCK_NONBLOCK))
+	{
+	case SOCK_STREAM:
+	case SOCK_DGRAM:
+	  /* the type argument serves a second purpose,
+	   * in addition to specifying a socket type,
+	   * it may include the bitwise OR of any of
+	   * SOCK_NONBLOCK and SOCK_CLOEXEC, to modify
+	   * the behavior of socket. */
+	  rv = libc_socket (domain, type, protocol);
+	  if (rv == -1)
+	    rv = -errno;
+	  break;
+
+	default:
+	  break;
+	}
+
+      break;
+
+    default:
+      break;
+    }
+
+  return rv;
+}
+
+static int
+vcom_socket_open_epoll (int flags)
+{
+  int rv = -1;
+
+  if (flags < 0)
+    {
+      return -EINVAL;
+    }
+  if (flags && (flags & ~EPOLL_CLOEXEC))
+    {
+      return -EINVAL;
+    }
+
+  /* flags can be either zero or EPOLL_CLOEXEC */
+  rv = libc_epoll_create1 (flags);
+  if (rv == -1)
+    rv = -errno;
+
+  return rv;
+}
+
+static int
+vcom_socket_close_socket (int fd)
+{
+  int rv;
+
+  rv = libc_close (fd);
+  if (rv == -1)
+    rv = -errno;
+
+  return rv;
+}
+
+static int
+vcom_socket_close_epoll (int epfd)
+{
+  int rv;
+
+  rv = libc_close (epfd);
+  if (rv == -1)
+    rv = -errno;
+
+  return rv;
+}
+
+/*
+ * Public API functions
+ */
+
+
+int
+vcom_socket_is_vcom_fd (int fd)
+{
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  uword *p;
+  vcom_socket_t *vsock;
+
+  p = hash_get (vsm->sockidx_by_fd, fd);
+
+  if (p)
+    {
+      vsock = pool_elt_at_index (vsm->vsockets, p[0]);
+      if (vsock && vsock->type == SOCKET_TYPE_VPPCOM_BOUND)
+	return 1;
+    }
+  return 0;
+}
+
+int
+vcom_socket_is_vcom_epfd (int epfd)
+{
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  uword *p;
+  vcom_epoll_t *vepoll;
+
+  p = hash_get (vsm->epollidx_by_epfd, epfd);
+
+  if (p)
+    {
+      vepoll = pool_elt_at_index (vsm->vepolls, p[0]);
+      if (vepoll && vepoll->type == EPOLL_TYPE_VPPCOM_BOUND)
+	return 1;
+    }
+  return 0;
+}
+
+static inline int
+vcom_socket_get_sid (int fd)
+{
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  uword *p;
+  vcom_socket_t *vsock;
+
+  p = hash_get (vsm->sockidx_by_fd, fd);
+
+  if (p)
+    {
+      vsock = pool_elt_at_index (vsm->vsockets, p[0]);
+      if (vsock && vsock->type == SOCKET_TYPE_VPPCOM_BOUND)
+	return vsock->sid;
+    }
+  return INVALID_SESSION_ID;
+}
+
+static inline int
+vcom_socket_get_vep_idx (int epfd)
+{
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  uword *p;
+  vcom_epoll_t *vepoll;
+
+  p = hash_get (vsm->epollidx_by_epfd, epfd);
+
+  if (p)
+    {
+      vepoll = pool_elt_at_index (vsm->vepolls, p[0]);
+      if (vepoll && vepoll->type == EPOLL_TYPE_VPPCOM_BOUND)
+	return vepoll->vep_idx;
+    }
+  return INVALID_VEP_IDX;
+}
+
+static inline int
+vcom_socket_get_sid_and_vsock (int fd, vcom_socket_t ** vsockp)
+{
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  uword *p;
+  vcom_socket_t *vsock;
+
+  p = hash_get (vsm->sockidx_by_fd, fd);
+
+  if (p)
+    {
+      vsock = pool_elt_at_index (vsm->vsockets, p[0]);
+      if (vsock && vsock->type == SOCKET_TYPE_VPPCOM_BOUND)
+	{
+	  *vsockp = vsock;
+	  return vsock->sid;
+	}
+    }
+  return INVALID_SESSION_ID;
+}
+
+static inline int
+vcom_socket_get_vep_idx_and_vepoll (int epfd, vcom_epoll_t ** vepollp)
+{
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  uword *p;
+  vcom_epoll_t *vepoll;
+
+  p = hash_get (vsm->epollidx_by_epfd, epfd);
+
+  if (p)
+    {
+      vepoll = pool_elt_at_index (vsm->vepolls, p[0]);
+      if (vepoll && vepoll->type == EPOLL_TYPE_VPPCOM_BOUND)
+	{
+	  *vepollp = vepoll;
+	  return vepoll->vep_idx;
+	}
+    }
+  return INVALID_VEP_IDX;
+}
+
+
+static int
+vcom_socket_close_vepoll (int epfd)
+{
+  int rv = -1;
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  uword *p;
+  vcom_epoll_t *vepoll;
+
+  p = hash_get (vsm->epollidx_by_epfd, epfd);
+  if (!p)
+    return -EBADF;
+
+  vepoll = pool_elt_at_index (vsm->vepolls, p[0]);
+  if (!vepoll)
+    return -EBADF;
+
+  if (vepoll->type != EPOLL_TYPE_VPPCOM_BOUND)
+    return -EINVAL;
+
+  if (vepoll->count)
+    {
+      if (!vepoll->close)
+	{
+	  vepoll->close = 1;
+	  return 0;
+	}
+      else
+	{
+	  return -EBADF;
+	}
+    }
+
+  /* count is zero */
+  rv = vppcom_session_close (vepoll->vep_idx);
+  rv = vcom_socket_close_epoll (vepoll->epfd);
+
+  vepoll_init (vepoll);
+  hash_unset (vsm->epollidx_by_epfd, epfd);
+  pool_put (vsm->vepolls, vepoll);
+
+  return rv;
+}
+
+static int
+vcom_socket_close_vsock (int fd)
+{
+  int rv = -1;
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  uword *p;
+  vcom_socket_t *vsock;
+
+  vcom_epitem_t *vepitem;
+
+  i32 *vepitemidxs = 0;
+  i32 *vepitemidxs_var = 0;
+
+  p = hash_get (vsm->sockidx_by_fd, fd);
+  if (!p)
+    return -EBADF;
+
+  vsock = pool_elt_at_index (vsm->vsockets, p[0]);
+  if (!vsock)
+    return -ENOTSOCK;
+
+  if (vsock->type != SOCKET_TYPE_VPPCOM_BOUND)
+    return -EINVAL;
+
+  rv = vppcom_session_close (vsock->sid);
+  rv = vcom_socket_close_socket (vsock->fd);
+
+  vsocket_init (vsock);
+  hash_unset (vsm->sockidx_by_fd, fd);
+  pool_put (vsm->vsockets, vsock);
+
+  /*
+   * NOTE:
+   * Before calling close(), user should remove
+   * this fd from the epoll-set of all epoll instances,
+   * otherwise resource(epitems) leaks ensues.
+   */
+
+  /*
+   * 00. close all epoll instances that are marked as "close"
+   *     of which this fd is the "last" remaining member.
+   * 01. epitems associated with this fd are intentionally
+   *     not removed, see NOTE: above.
+   * */
+
+  /* does this fd participate in epoll */
+  p = hash_get (vsm->epitemidxs_by_fd, fd);
+  if (p)
+    {
+      vepitemidxs = *(i32 **) p;
+      vec_foreach (vepitemidxs_var, vepitemidxs)
+      {
+	vepitem = pool_elt_at_index (vsm->vepitems, vepitemidxs_var[0]);
+	if (vepitem && vepitem->fd == fd &&
+	    vepitem->type == FD_TYPE_VCOM_SOCKET)
+	  {
+	    i32 vep_idx;
+	    vcom_epoll_t *vepoll;
+	    if ((vep_idx =
+		 vcom_socket_get_vep_idx_and_vepoll (vepitem->epfd,
+						     &vepoll)) !=
+		INVALID_VEP_IDX)
+	      {
+		if (vepoll->close)
+		  {
+		    if (vepoll->count == 1)
+		      {
+			/*
+			 * force count to zero and
+			 * close this epoll instance
+			 * */
+			vepoll->count = 0;
+			vcom_socket_close_vepoll (vepoll->epfd);
+		      }
+		    else
+		      {
+			vepoll->count -= 1;
+		      }
+		  }
+	      }
+	  }
+
+      }
+    }
+
+  return rv;
+}
+
+int
+vcom_socket_close (int __fd)
+{
+  int rv;
+
+  if (vcom_socket_is_vcom_fd (__fd))
+    {
+      rv = vcom_socket_close_vsock (__fd);
+    }
+  else if (vcom_socket_is_vcom_epfd (__fd))
+    {
+      rv = vcom_socket_close_vepoll (__fd);
+    }
+  else
+    {
+      rv = -EBADF;
+    }
+
+  return rv;
+}
+
+ssize_t
+vcom_socket_read (int __fd, void *__buf, size_t __nbytes)
+{
+  int rv = -1;
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  uword *p;
+  vcom_socket_t *vsock;
+
+  p = hash_get (vsm->sockidx_by_fd, __fd);
+  if (!p)
+    return -EBADF;
+
+  vsock = pool_elt_at_index (vsm->vsockets, p[0]);
+  if (!vsock)
+    return -ENOTSOCK;
+
+  if (vsock->type != SOCKET_TYPE_VPPCOM_BOUND)
+    return -EINVAL;
+
+  if (!__buf)
+    {
+      return -EINVAL;
+    }
+
+  rv = vcom_fcntl (__fd, F_GETFL, 0);
+  if (rv < 0)
+    {
+      return rv;
+
+    }
+
+  /* is blocking */
+  if (!(rv & O_NONBLOCK))
+    {
+      do
+	{
+	  rv = vppcom_session_read (vsock->sid, __buf, __nbytes);
+	}
+      while (rv == -EAGAIN || rv == -EWOULDBLOCK);
+      return rv;
+    }
+  /* The file descriptor refers to a socket and has been
+   * marked nonblocking(O_NONBLOCK) and the read would
+   * block.
+   * */
+  /* is non blocking */
+  rv = vppcom_session_read (vsock->sid, __buf, __nbytes);
+  return rv;
+}
+
+ssize_t
+vcom_socket_readv (int __fd, const struct iovec * __iov, int __iovcnt)
+{
+  int rv;
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  uword *p;
+  vcom_socket_t *vsock;
+  ssize_t total = 0, len = 0;
+  int i;
+
+  p = hash_get (vsm->sockidx_by_fd, __fd);
+  if (!p)
+    return -EBADF;
+
+  vsock = pool_elt_at_index (vsm->vsockets, p[0]);
+  if (!vsock)
+    return -ENOTSOCK;
+
+  if (vsock->type != SOCKET_TYPE_VPPCOM_BOUND)
+    return -EINVAL;
+
+  if (__iov == 0 || __iovcnt == 0 || __iovcnt > IOV_MAX)
+    return -EINVAL;
+
+  /* Sanity check */
+  for (i = 0; i < __iovcnt; ++i)
+    {
+      if (SSIZE_MAX - len < __iov[i].iov_len)
+	return -EINVAL;
+      len += __iov[i].iov_len;
+    }
+
+  rv = vcom_fcntl (__fd, F_GETFL, 0);
+  if (rv < 0)
+    {
+      return rv;
+    }
+
+  /* is blocking */
+  if (!(rv & O_NONBLOCK))
+    {
+      do
+	{
+	  for (i = 0; i < __iovcnt; ++i)
+	    {
+	      rv = vppcom_session_read (vsock->sid, __iov[i].iov_base,
+					__iov[i].iov_len);
+	      if (rv < 0)
+		break;
+	      else
+		{
+		  total += rv;
+		  if (rv < __iov[i].iov_len)
+		    /* Read less than buffer provided, no point to continue */
+		    break;
+		}
+	    }
+	}
+      while ((rv == -EAGAIN || rv == -EWOULDBLOCK) && total == 0);
+      return total;
+    }
+
+  /* is non blocking */
+  for (i = 0; i < __iovcnt; ++i)
+    {
+      rv = vppcom_session_read (vsock->sid, __iov[i].iov_base,
+				__iov[i].iov_len);
+      if (rv < 0)
+	{
+	  if (total > 0)
+	    break;
+	  else
+	    {
+	      errno = rv;
+	      return rv;
+	    }
+	}
+      else
+	{
+	  total += rv;
+	  if (rv < __iov[i].iov_len)
+	    /* Read less than buffer provided, no point to continue */
+	    break;
+	}
+    }
+  return total;
+}
+
+ssize_t
+vcom_socket_write (int __fd, const void *__buf, size_t __n)
+{
+  int rv = -1;
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  uword *p;
+  vcom_socket_t *vsock;
+
+  if (!__buf)
+    {
+      return -EINVAL;
+    }
+
+  p = hash_get (vsm->sockidx_by_fd, __fd);
+  if (!p)
+    return -EBADF;
+
+  vsock = pool_elt_at_index (vsm->vsockets, p[0]);
+  if (!vsock)
+    return -ENOTSOCK;
+
+  if (vsock->type != SOCKET_TYPE_VPPCOM_BOUND)
+    return -EINVAL;
+
+  rv = vppcom_session_write (vsock->sid, (void *) __buf, __n);
+  return rv;
+}
+
+ssize_t
+vcom_socket_writev (int __fd, const struct iovec * __iov, int __iovcnt)
+{
+  int rv = -1;
+  ssize_t total = 0;
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  uword *p;
+  vcom_socket_t *vsock;
+  int i;
+
+  p = hash_get (vsm->sockidx_by_fd, __fd);
+  if (!p)
+    return -EBADF;
+
+  vsock = pool_elt_at_index (vsm->vsockets, p[0]);
+  if (!vsock)
+    return -ENOTSOCK;
+
+  if (vsock->type != SOCKET_TYPE_VPPCOM_BOUND)
+    return -EINVAL;
+
+  if (__iov == 0 || __iovcnt == 0 || __iovcnt > IOV_MAX)
+    return -EINVAL;
+
+  for (i = 0; i < __iovcnt; ++i)
+    {
+      rv = vppcom_session_write (vsock->sid, __iov[i].iov_base,
+				 __iov[i].iov_len);
+      if (rv < 0)
+	{
+	  if (total > 0)
+	    break;
+	  else
+	    return rv;
+	}
+      else
+	total += rv;
+    }
+  return total;
+}
+
+/*
+ * RETURN:  0 - invalid cmd
+ *          1 - cmd not handled by vcom and vppcom
+ *          2 - cmd handled by vcom socket resource
+ *          3 - cmd handled by vppcom
+ * */
+/* TBD: incomplete list of cmd */
+static int
+vcom_socket_check_fcntl_cmd (int __cmd)
+{
+  switch (__cmd)
+    {
+      /*cmd not handled by vcom and vppcom */
+      /* Fallthrough */
+    case F_DUPFD:
+    case F_DUPFD_CLOEXEC:
+      return 1;
+
+      /* cmd handled by vcom socket resource */
+      /* Fallthrough */
+    case F_GETFD:
+    case F_SETFD:
+    case F_GETLK:
+    case F_SETLK:
+    case F_SETLKW:
+    case F_GETOWN:
+    case F_SETOWN:
+      return 2;
+
+      /* cmd handled by vcom and vppcom */
+    case F_SETFL:
+    case F_GETFL:
+      return 3;
+
+      /* cmd not handled by vcom and vppcom */
+    default:
+      return 1;
+    }
+  return 0;
+}
+
+static inline int
+vcom_session_fcntl_va (int __sid, int __cmd, va_list __ap)
+{
+  int flags = va_arg (__ap, int);
+  int rv = -EOPNOTSUPP;
+  uint32_t size;
+
+  size = sizeof (flags);
+  if (__cmd == F_SETFL)
+    {
+      rv = vppcom_session_attr (__sid, VPPCOM_ATTR_SET_FLAGS, &flags, &size);
+    }
+  else if (__cmd == F_GETFL)
+    {
+      rv = vppcom_session_attr (__sid, VPPCOM_ATTR_GET_FLAGS, &flags, &size);
+      if (rv == VPPCOM_OK)
+	rv = flags;
+    }
+
+  return rv;
+}
+
+int
+vcom_socket_fcntl_va (int __fd, int __cmd, va_list __ap)
+{
+  int rv = -EBADF;
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  uword *p;
+  vcom_socket_t *vsock;
+
+  p = hash_get (vsm->sockidx_by_fd, __fd);
+  if (!p)
+    return -EBADF;
+
+  vsock = pool_elt_at_index (vsm->vsockets, p[0]);
+  if (!vsock)
+    return -ENOTSOCK;
+
+  if (vsock->type != SOCKET_TYPE_VPPCOM_BOUND)
+    return -EINVAL;
+
+  switch (vcom_socket_check_fcntl_cmd (__cmd))
+    {
+      /* invalid cmd */
+    case 0:
+      rv = -EBADF;
+      break;
+      /*cmd not handled by vcom and vppcom */
+    case 1:
+      rv = libc_vfcntl (vsock->fd, __cmd, __ap);
+      break;
+      /* cmd handled by vcom socket resource */
+    case 2:
+      rv = libc_vfcntl (vsock->fd, __cmd, __ap);
+      break;
+      /* cmd handled by vppcom */
+    case 3:
+      rv = vcom_session_fcntl_va (vsock->sid, __cmd, __ap);
+      break;
+
+    default:
+      rv = -EINVAL;
+      break;
+    }
+
+  return rv;
+}
+
+/*
+ * RETURN:  0 - invalid cmd
+ *          1 - cmd not handled by vcom and vppcom
+ *          2 - cmd handled by vcom socket resource
+ *          3 - cmd handled by vppcom
+ */
+static int
+vcom_socket_check_ioctl_cmd (unsigned long int __cmd)
+{
+  int rc;
+
+  switch (__cmd)
+    {
+      /* cmd handled by vppcom */
+    case FIONREAD:
+      rc = 3;
+      break;
+
+      /* cmd not handled by vcom and vppcom */
+    default:
+      rc = 1;
+      break;
+    }
+  return rc;
+}
+
+static inline int
+vcom_session_ioctl_va (int __sid, int __cmd, va_list __ap)
+{
+  int rv;
+
+  if (__cmd == FIONREAD)
+    rv = vppcom_session_attr (__sid, VPPCOM_ATTR_GET_NREAD, 0, 0);
+  else
+    rv = -EOPNOTSUPP;
+  return rv;
+}
+
+int
+vcom_socket_ioctl_va (int __fd, unsigned long int __cmd, va_list __ap)
+{
+  int rv = -EBADF;
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  uword *p;
+  vcom_socket_t *vsock;
+
+  p = hash_get (vsm->sockidx_by_fd, __fd);
+  if (!p)
+    return -EBADF;
+
+  vsock = pool_elt_at_index (vsm->vsockets, p[0]);
+  if (!vsock)
+    return -ENOTSOCK;
+
+  if (vsock->type != SOCKET_TYPE_VPPCOM_BOUND)
+    return -EINVAL;
+
+  switch (vcom_socket_check_ioctl_cmd (__cmd))
+    {
+      /* Not supported cmd */
+    case 0:
+      rv = -EOPNOTSUPP;
+      break;
+
+      /* cmd not handled by vcom and vppcom */
+    case 1:
+      rv = libc_vioctl (vsock->fd, __cmd, __ap);
+      break;
+
+      /* cmd handled by vcom socket resource */
+    case 2:
+      rv = libc_vioctl (vsock->fd, __cmd, __ap);
+      break;
+
+      /* cmd handled by vppcom */
+    case 3:
+      rv = vcom_session_ioctl_va (vsock->sid, __cmd, __ap);
+      break;
+
+    default:
+      rv = -EINVAL;
+      break;
+    }
+
+  return rv;
+}
+
+static inline int
+vcom_socket_fds_2_sid_fds (
+			    /* dest */
+			    int *vcom_nsid_fds,
+			    fd_set * __restrict vcom_rd_sid_fds,
+			    fd_set * __restrict vcom_wr_sid_fds,
+			    fd_set * __restrict vcom_ex_sid_fds,
+			    /* src */
+			    int vcom_nfds,
+			    fd_set * __restrict vcom_readfds,
+			    fd_set * __restrict vcom_writefds,
+			    fd_set * __restrict vcom_exceptfds)
+{
+  int rv = 0;
+  int fd;
+  int sid;
+  /* invalid max_sid is -1 */
+  int max_sid = -1;
+  int nsid = 0;
+
+  /*
+   *  set sid in sid sets corresponding to fd's in fd sets
+   *  compute nsid and vcom_nsid_fds from sid sets
+   */
+
+  for (fd = 0; fd < vcom_nfds; fd++)
+    {
+      /*
+       * F fd set, src
+       * S sid set, dest
+       */
+#define _(S,F)                              \
+      if ((F) && (S) && FD_ISSET (fd, (F))) \
+        {                                   \
+          sid = vcom_socket_get_sid (fd);   \
+          if (sid != INVALID_SESSION_ID)    \
+            {                               \
+              FD_SET (sid, (S));            \
+              if (sid > max_sid)            \
+                {                           \
+                  max_sid = sid;            \
+                }                           \
+              ++nsid;                       \
+            }                               \
+          else                              \
+            {                               \
+              rv = -EBADFD;                 \
+              goto done;                    \
+            }                               \
+        }
+
+
+      _(vcom_rd_sid_fds, vcom_readfds);
+      _(vcom_wr_sid_fds, vcom_writefds);
+      _(vcom_ex_sid_fds, vcom_exceptfds);
+#undef _
+    }
+
+  *vcom_nsid_fds = max_sid != -1 ? max_sid + 1 : 0;
+  rv = nsid;
+
+done:
+  return rv;
+}
+
+/*
+ * PRE: 00. sid sets were derived from fd sets
+ *      01. sid sets were updated with sids that actually changed
+ *          status
+ *      02. fd sets still has watched fds
+ *
+ * This function will modify in place fd sets to indicate which fd's
+ * actually changed status(inferred from sid sets)
+ */
+static inline int
+vcom_socket_sid_fds_2_fds (
+			    /* dest */
+			    int *new_vcom_nfds,
+			    int vcom_nfds,
+			    fd_set * __restrict vcom_readfds,
+			    fd_set * __restrict vcom_writefds,
+			    fd_set * __restrict vcom_exceptfds,
+			    /* src */
+			    int vcom_nsid_fds,
+			    fd_set * __restrict vcom_rd_sid_fds,
+			    fd_set * __restrict vcom_wr_sid_fds,
+			    fd_set * __restrict vcom_ex_sid_fds)
+{
+  int rv = 0;
+  int fd;
+  int sid;
+  /* invalid max_fd is -1 */
+  int max_fd = -1;
+  int nfd = 0;
+
+
+  /*
+   *  modify in place fd sets to indicate which fd's
+   * actually changed status(inferred from sid sets)
+   */
+  for (fd = 0; fd < vcom_nfds; fd++)
+    {
+      /*
+       * F fd set, dest
+       * S sid set, src
+       */
+#define _(S,F)                              \
+      if ((F) && (S) && FD_ISSET (fd, (F))) \
+        {                                   \
+          sid = vcom_socket_get_sid (fd);   \
+          if (sid != INVALID_SESSION_ID)    \
+            {                               \
+              if (!FD_ISSET (sid, (S)))     \
+                {                           \
+                   FD_CLR(fd, (F));         \
+                }                           \
+            }                               \
+          else                              \
+            {                               \
+              rv = -EBADFD;                 \
+              goto done;                    \
+            }                               \
+        }
+
+
+      _(vcom_rd_sid_fds, vcom_readfds);
+      _(vcom_wr_sid_fds, vcom_writefds);
+      _(vcom_ex_sid_fds, vcom_exceptfds);
+#undef _
+    }
+
+  /*
+   *  compute nfd and new_vcom_nfds from fd sets
+   */
+  for (fd = 0; fd < vcom_nfds; fd++)
+    {
+
+#define _(F)                                \
+      if ((F) && FD_ISSET (fd, (F)))        \
+        {                                   \
+          if (fd > max_fd)                  \
+            {                               \
+              max_fd = fd;                  \
+            }                               \
+          ++nfd;                            \
+        }
+
+
+      _(vcom_readfds);
+      _(vcom_writefds);
+      _(vcom_exceptfds);
+#undef _
+
+    }
+
+  *new_vcom_nfds = max_fd != -1 ? max_fd + 1 : 0;
+  rv = nfd;
+
+done:
+  return rv;
+}
+
+/*
+ * PRE:
+ * vom_socket_select is always called with
+ * timeout->tv_sec and timeout->tv_usec set to zero.
+ * hence vppcom_select return immediately.
+ */
+/*
+ * TBD: do{body;} while(timeout conditional); timeout loop
+ */
+int
+vcom_socket_select (int vcom_nfds, fd_set * __restrict vcom_readfds,
+		    fd_set * __restrict vcom_writefds,
+		    fd_set * __restrict vcom_exceptfds,
+		    struct timeval *__restrict timeout)
+{
+  static unsigned long vcom_nsid_fds = 0;
+  int vcom_nsid = 0;
+  int rv = -EBADF;
+  pid_t pid = getpid ();
+
+  int new_vcom_nfds = 0;
+  int new_vcom_nfd = 0;
+
+  /* vcom sid fds */
+  fd_set vcom_rd_sid_fds;
+  fd_set vcom_wr_sid_fds;
+  fd_set vcom_ex_sid_fds;
+
+  /* in seconds eg. 3.123456789 seconds */
+  double time_to_wait = (double) 0;
+
+  /* validate inputs */
+  if (vcom_nfds < 0)
+    {
+      return -EINVAL;
+    }
+
+  /* convert timeval timeout to double time_to_wait */
+  if (timeout)
+    {
+      if (timeout->tv_sec == 0 && timeout->tv_usec == 0)
+	{
+	  /* polling: vppcom_select returns immediately */
+	  time_to_wait = (double) 0;
+	}
+      else
+	{
+	  /*TBD:  use timeval api */
+	  time_to_wait = (double) timeout->tv_sec +
+	    (double) timeout->tv_usec / (double) 1000000 +
+	    (double) (timeout->tv_usec % 1000000) / (double) 1000000;
+	}
+    }
+  else
+    {
+      /*
+       * no timeout: vppcom_select can block indefinitely
+       * waiting for a file descriptor to become ready
+       * */
+      /* set to a phantom value */
+      time_to_wait = ~0;
+    }
+
+  /* zero the sid_sets */
+  /*
+   * F fd set
+   * S sid set
+   */
+#define _(S,F)                          \
+  if ((F))                              \
+    {                                   \
+      FD_ZERO ((S));                    \
+    }
+
+
+  _(&vcom_rd_sid_fds, vcom_readfds);
+  _(&vcom_wr_sid_fds, vcom_writefds);
+  _(&vcom_ex_sid_fds, vcom_exceptfds);
+#undef _
+
+  if (vcom_nfds == 0)
+    {
+      if (time_to_wait > 0)
+	{
+	  if (VCOM_DEBUG > 0)
+	    fprintf (stderr,
+		     "[%d] vcom_socket_select called to "
+		     "emulate delay_ns()!\n", pid);
+	  rv = vppcom_select (0, NULL, NULL, NULL, time_to_wait);
+	}
+      else
+	{
+	  fprintf (stderr, "[%d] vcom_socket_select called vcom_nfds = 0 "
+		   "and invalid time_to_wait (%f)!\n", pid, time_to_wait);
+	}
+      return 0;
+    }
+
+  /* populate read, write and except sid_sets */
+  vcom_nsid = vcom_socket_fds_2_sid_fds (
+					  /* dest */
+					  vcom_readfds || vcom_writefds
+					  || vcom_exceptfds ? (int *)
+					  &vcom_nsid_fds : NULL,
+					  vcom_readfds ? &vcom_rd_sid_fds :
+					  NULL,
+					  vcom_writefds ? &vcom_wr_sid_fds :
+					  NULL,
+					  vcom_exceptfds ? &vcom_ex_sid_fds :
+					  NULL,
+					  /* src */
+					  vcom_nfds,
+					  vcom_readfds,
+					  vcom_writefds, vcom_exceptfds);
+  if (vcom_nsid < 0)
+    {
+      return vcom_nsid;
+    }
+
+  rv = vppcom_select (vcom_nsid_fds,
+		      vcom_readfds ? (unsigned long *) &vcom_rd_sid_fds :
+		      NULL,
+		      vcom_writefds ? (unsigned long *) &vcom_wr_sid_fds :
+		      NULL,
+		      vcom_exceptfds ? (unsigned long *) &vcom_ex_sid_fds :
+		      NULL, time_to_wait);
+  if (VCOM_DEBUG > 2)
+    fprintf (stderr, "[%d] called vppcom_select(): "
+	     "'%04d'='%04d'\n", pid, rv, (int) vcom_nsid_fds);
+
+  /* check if any file descriptors changed status */
+  if (rv > 0)
+    {
+      /*
+       * on exit, sets are modified in place to indicate which
+       * file descriptors actually changed status
+       * */
+
+      /*
+       * comply with pre-condition
+       * do not clear vcom fd sets befor calling
+       * vcom_socket_sid_fds_2_fds
+       */
+      new_vcom_nfd = vcom_socket_sid_fds_2_fds (
+						 /* dest */
+						 &new_vcom_nfds,
+						 vcom_nfds,
+						 vcom_readfds,
+						 vcom_writefds,
+						 vcom_exceptfds,
+						 /* src */
+						 vcom_nsid_fds,
+						 vcom_readfds ?
+						 &vcom_rd_sid_fds : NULL,
+						 vcom_writefds ?
+						 &vcom_wr_sid_fds : NULL,
+						 vcom_exceptfds ?
+						 &vcom_ex_sid_fds : NULL);
+      if (new_vcom_nfd < 0)
+	{
+	  return new_vcom_nfd;
+	}
+      if (new_vcom_nfds < 0)
+	{
+	  return -EINVAL;
+	}
+      rv = new_vcom_nfd;
+    }
+  return rv;
+}
+
+
+int
+vcom_socket_socket (int __domain, int __type, int __protocol)
+{
+  int rv = -1;
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  vcom_socket_t *vsock;
+
+  i32 fd;
+  i32 sid;
+  i32 sockidx;
+  u8 is_nonblocking = __type & SOCK_NONBLOCK ? 1 : 0;
+  int type = __type & ~(SOCK_NONBLOCK | SOCK_CLOEXEC);
+
+  fd = vcom_socket_open_socket (__domain, __type, __protocol);
+  if (fd < 0)
+    {
+      rv = fd;
+      goto out;
+    }
+
+  sid = vppcom_session_create (VPPCOM_VRF_DEFAULT,
+			       (type == SOCK_DGRAM) ?
+			       VPPCOM_PROTO_UDP : VPPCOM_PROTO_TCP,
+			       is_nonblocking);
+  if (sid < 0)
+    {
+      rv = sid;
+      goto out_close_socket;
+    }
+
+  pool_get (vsm->vsockets, vsock);
+  vsocket_init (vsock);
+
+  sockidx = vsock - vsm->vsockets;
+  hash_set (vsm->sockidx_by_fd, fd, sockidx);
+
+  vsocket_set (vsock, fd, sid, SOCKET_TYPE_VPPCOM_BOUND);
+  return fd;
+
+out_close_socket:
+  vcom_socket_close_socket (fd);
+out:
+  return rv;
+}
+
+int
+vcom_socket_socketpair (int __domain, int __type, int __protocol,
+			int __fds[2])
+{
+/* TBD: */
+  return 0;
+}
+
+int
+vcom_socket_bind (int __fd, __CONST_SOCKADDR_ARG __addr, socklen_t __len)
+{
+  int rv = -1;
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  uword *p;
+  vcom_socket_t *vsock;
+
+  vppcom_endpt_t ep;
+
+  p = hash_get (vsm->sockidx_by_fd, __fd);
+  if (!p)
+    return -EBADF;
+
+  vsock = pool_elt_at_index (vsm->vsockets, p[0]);
+  if (!vsock)
+    return -ENOTSOCK;
+
+  if (vsock->type != SOCKET_TYPE_VPPCOM_BOUND)
+    return -EINVAL;
+
+  if (!__addr)
+    {
+      return -EINVAL;
+    }
+
+  ep.vrf = VPPCOM_VRF_DEFAULT;
+  switch (__addr->sa_family)
+    {
+    case AF_INET:
+      if (__len != sizeof (struct sockaddr_in))
+	{
+	  return -EINVAL;
+	}
+      ep.is_ip4 = VPPCOM_IS_IP4;
+      ep.ip = (u8 *) & ((const struct sockaddr_in *) __addr)->sin_addr;
+      ep.port = (u16) ((const struct sockaddr_in *) __addr)->sin_port;
+      break;
+
+    case AF_INET6:
+      if (__len != sizeof (struct sockaddr_in6))
+	{
+	  return -EINVAL;
+	}
+      ep.is_ip4 = VPPCOM_IS_IP6;
+      ep.ip = (u8 *) & ((const struct sockaddr_in6 *) __addr)->sin6_addr;
+      ep.port = (u16) ((const struct sockaddr_in6 *) __addr)->sin6_port;
+      break;
+
+    default:
+      return -1;
+      break;
+    }
+
+  rv = vppcom_session_bind (vsock->sid, &ep);
+  return rv;
+}
+
+static inline int
+vcom_session_getsockname (int sid, vppcom_endpt_t * ep)
+{
+  int rv;
+  uint32_t size = sizeof (*ep);
+
+  rv = vppcom_session_attr (sid, VPPCOM_ATTR_GET_LCL_ADDR, ep, &size);
+  return rv;
+}
+
+int
+vcom_socket_getsockname (int __fd, __SOCKADDR_ARG __addr,
+			 socklen_t * __restrict __len)
+{
+  int rv = -1;
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  uword *p;
+  vcom_socket_t *vsock;
+
+
+  p = hash_get (vsm->sockidx_by_fd, __fd);
+  if (!p)
+    return -EBADF;
+
+  vsock = pool_elt_at_index (vsm->vsockets, p[0]);
+  if (!vsock)
+    return -ENOTSOCK;
+
+  if (vsock->type != SOCKET_TYPE_VPPCOM_BOUND)
+    return -EINVAL;
+
+  if (!__addr || !__len)
+    return -EFAULT;
+
+  vppcom_endpt_t ep;
+  ep.ip = (u8 *) & ((const struct sockaddr_in *) __addr)->sin_addr;
+  rv = vcom_session_getsockname (vsock->sid, &ep);
+  if (rv == 0)
+    {
+      if (ep.vrf == VPPCOM_VRF_DEFAULT)
+	{
+	  __addr->sa_family = ep.is_ip4 == VPPCOM_IS_IP4 ? AF_INET : AF_INET6;
+	  switch (__addr->sa_family)
+	    {
+	    case AF_INET:
+	      ((struct sockaddr_in *) __addr)->sin_port = ep.port;
+	      *__len = sizeof (struct sockaddr_in);
+	      break;
+
+	    case AF_INET6:
+	      ((struct sockaddr_in6 *) __addr)->sin6_port = ep.port;
+	      *__len = sizeof (struct sockaddr_in6);
+	      break;
+
+	    default:
+	      break;
+	    }
+	}
+    }
+
+  return rv;
+}
+
+int
+vcom_socket_connect (int __fd, __CONST_SOCKADDR_ARG __addr, socklen_t __len)
+{
+  int rv = -1;
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  uword *p;
+  vcom_socket_t *vsock;
+
+  vppcom_endpt_t ep;
+
+  p = hash_get (vsm->sockidx_by_fd, __fd);
+  if (p)
+    {
+      vsock = pool_elt_at_index (vsm->vsockets, p[0]);
+
+      ep.vrf = VPPCOM_VRF_DEFAULT;
+      switch (__addr->sa_family)
+	{
+	case AF_INET:
+	  ep.is_ip4 = VPPCOM_IS_IP4;
+	  ep.ip =
+	    (uint8_t *) & ((const struct sockaddr_in *) __addr)->sin_addr;
+	  ep.port =
+	    (uint16_t) ((const struct sockaddr_in *) __addr)->sin_port;
+	  break;
+
+	case AF_INET6:
+	  ep.is_ip4 = VPPCOM_IS_IP6;
+	  ep.ip =
+	    (uint8_t *) & ((const struct sockaddr_in6 *) __addr)->sin6_addr;
+	  ep.port =
+	    (uint16_t) ((const struct sockaddr_in6 *) __addr)->sin6_port;
+	  break;
+
+	default:
+	  return -1;
+	  break;
+	}
+
+      rv = vppcom_session_connect (vsock->sid, &ep);
+    }
+  return rv;
+}
+
+static inline int
+vcom_session_getpeername (int sid, vppcom_endpt_t * ep)
+{
+  int rv;
+  uint32_t size = sizeof (*ep);
+
+  rv = vppcom_session_attr (sid, VPPCOM_ATTR_GET_PEER_ADDR, ep, &size);
+  return rv;
+}
+
+int
+vcom_socket_getpeername (int __fd, __SOCKADDR_ARG __addr,
+			 socklen_t * __restrict __len)
+{
+  int rv = -1;
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  uword *p;
+  vcom_socket_t *vsock;
+
+
+  p = hash_get (vsm->sockidx_by_fd, __fd);
+  if (!p)
+    return -EBADF;
+
+  vsock = pool_elt_at_index (vsm->vsockets, p[0]);
+  if (!vsock)
+    return -ENOTSOCK;
+
+  if (vsock->type != SOCKET_TYPE_VPPCOM_BOUND)
+    return -EINVAL;
+
+  if (!__addr || !__len)
+    return -EFAULT;
+
+  vppcom_endpt_t ep;
+  ep.ip = (u8 *) & ((const struct sockaddr_in *) __addr)->sin_addr;
+  rv = vcom_session_getpeername (vsock->sid, &ep);
+  if (rv == 0)
+    {
+      if (ep.vrf == VPPCOM_VRF_DEFAULT)
+	{
+	  __addr->sa_family = ep.is_ip4 == VPPCOM_IS_IP4 ? AF_INET : AF_INET6;
+	  switch (__addr->sa_family)
+	    {
+	    case AF_INET:
+	      ((struct sockaddr_in *) __addr)->sin_port = ep.port;
+	      *__len = sizeof (struct sockaddr_in);
+	      break;
+
+	    case AF_INET6:
+	      ((struct sockaddr_in6 *) __addr)->sin6_port = ep.port;
+	      *__len = sizeof (struct sockaddr_in6);
+	      break;
+
+	    default:
+	      break;
+	    }
+	}
+    }
+
+  return rv;
+}
+
+ssize_t
+vcom_socket_send (int __fd, const void *__buf, size_t __n, int __flags)
+{
+  return vcom_socket_sendto (__fd, __buf, __n, __flags, NULL, 0);
+}
+
+ssize_t
+vcom_socket_recv (int __fd, void *__buf, size_t __n, int __flags)
+{
+  int rv = -1;
+  rv = vcom_socket_recvfrom (__fd, __buf, __n, __flags, NULL, 0);
+  return rv;
+}
+
+/*
+ * RETURN   1 if __fd is (SOCK_STREAM, SOCK_SEQPACKET),
+ * 0 otherwise
+ * */
+int
+vcom_socket_is_connection_mode_socket (int __fd)
+{
+  int rv = -1;
+  /* TBD define new vppcom api */
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  uword *p;
+  vcom_socket_t *vsock;
+
+  int type;
+  socklen_t optlen;
+
+  p = hash_get (vsm->sockidx_by_fd, __fd);
+
+  if (p)
+    {
+      vsock = pool_elt_at_index (vsm->vsockets, p[0]);
+      if (vsock && vsock->type == SOCKET_TYPE_VPPCOM_BOUND)
+	{
+	  optlen = sizeof (type);
+	  rv = libc_getsockopt (__fd, SOL_SOCKET, SO_TYPE, &type, &optlen);
+	  if (rv != 0)
+	    {
+	      return 0;
+	    }
+	  /* get socket type */
+	  switch (type & ~(SOCK_CLOEXEC | SOCK_NONBLOCK))
+	    {
+	    case SOCK_STREAM:
+	    case SOCK_SEQPACKET:
+	      return 1;
+	      break;
+
+	    default:
+	      return 0;
+	      break;
+	    }
+	}
+    }
+  return 0;
+}
+
+static inline ssize_t
+vcom_session_sendto (int __sid, void *__buf, size_t __n,
+		     int __flags, __CONST_SOCKADDR_ARG __addr,
+		     socklen_t __addr_len)
+{
+  int rv = -1;
+  /* TBD add new vpp api  */
+  /* TBD add flags parameter */
+  rv = vppcom_session_write (__sid, (void *) __buf, (int) __n);
+  return rv;
+}
+
+ssize_t
+vcom_socket_sendto (int __fd, const void *__buf, size_t __n,
+		    int __flags, __CONST_SOCKADDR_ARG __addr,
+		    socklen_t __addr_len)
+{
+  int rv = -1;
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  uword *p;
+  vcom_socket_t *vsock;
+
+  if (!__buf)
+    {
+      return -EINVAL;
+    }
+
+  p = hash_get (vsm->sockidx_by_fd, __fd);
+  if (!p)
+    return -EBADF;
+
+  vsock = pool_elt_at_index (vsm->vsockets, p[0]);
+  if (!vsock)
+    return -ENOTSOCK;
+
+  if (vsock->type != SOCKET_TYPE_VPPCOM_BOUND)
+    {
+      return -EINVAL;
+    }
+
+  if (vcom_socket_is_connection_mode_socket (__fd))
+    {
+      /* ignore __addr and _addr_len */
+      /* and EISCONN may be returned when they are not NULL and 0 */
+      if ((__addr != NULL) || (__addr_len != 0))
+	{
+	  return -EISCONN;
+	}
+    }
+  else
+    {
+      if (!__addr)
+	{
+	  return -EDESTADDRREQ;
+	}
+      /* not a vppcom supported address family */
+      if ((__addr->sa_family != AF_INET) || (__addr->sa_family != AF_INET6))
+	{
+	  return -EINVAL;
+	}
+    }
+
+  rv = vcom_session_sendto (vsock->sid, (void *) __buf, (int) __n,
+			    __flags, __addr, __addr_len);
+  return rv;
+}
+
+static inline ssize_t
+vcom_session_recvfrom (int __sid, void *__restrict __buf, size_t __n,
+		       int __flags, __SOCKADDR_ARG __addr,
+		       socklen_t * __restrict __addr_len)
+{
+  int rv = -1;
+
+  /* TBD add flags parameter */
+  rv = vppcom_session_read (__sid, __buf, __n);
+  return rv;
+}
+
+ssize_t
+vcom_socket_recvfrom (int __fd, void *__restrict __buf, size_t __n,
+		      int __flags, __SOCKADDR_ARG __addr,
+		      socklen_t * __restrict __addr_len)
+{
+  int rv = -1;
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  uword *p;
+  vcom_socket_t *vsock;
+
+  if (!__buf || !__addr || !__addr_len)
+    {
+      return -EINVAL;
+    }
+
+  p = hash_get (vsm->sockidx_by_fd, __fd);
+  if (!p)
+    return -EBADF;
+
+  vsock = pool_elt_at_index (vsm->vsockets, p[0]);
+  if (!vsock)
+    return -ENOTSOCK;
+
+  if (vsock->type != SOCKET_TYPE_VPPCOM_BOUND)
+    {
+      return -EINVAL;
+    }
+
+  rv = vcom_session_recvfrom (vsock->sid, __buf, __n,
+			      __flags, __addr, __addr_len);
+  return rv;
+}
+
+/* TBD: move it to vppcom */
+static inline ssize_t
+vcom_session_sendmsg (int __sid, const struct msghdr *__message, int __flags)
+{
+  int rv = -1;
+  /* rv = vppcom_session_write (__sid, (void *) __message->__buf,
+     (int)__n); */
+  return rv;
+}
+
+ssize_t
+vcom_socket_sendmsg (int __fd, const struct msghdr * __message, int __flags)
+{
+  int rv = -1;
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  uword *p;
+  vcom_socket_t *vsock;
+
+  p = hash_get (vsm->sockidx_by_fd, __fd);
+  if (!p)
+    return -EBADF;
+
+  vsock = pool_elt_at_index (vsm->vsockets, p[0]);
+  if (!vsock)
+    return -ENOTSOCK;
+
+  if (vcom_socket_is_connection_mode_socket (__fd))
+    {
+      /* ignore __addr and _addr_len */
+      /* and EISCONN may be returned when they are not NULL and 0 */
+      if ((__message->msg_name != NULL) || (__message->msg_namelen != 0))
+	{
+	  return -EISCONN;
+	}
+    }
+  else
+    {
+      /* TBD: validate __message->msg_name and __message->msg_namelen
+       * and return -EINVAL on validation error
+       * */
+      ;
+    }
+
+  rv = vcom_session_sendmsg (vsock->sid, __message, __flags);
+
+  return rv;
+}
+
+#ifdef __USE_GNU
+int
+vcom_socket_sendmmsg (int __fd, struct mmsghdr *__vmessages,
+		      unsigned int __vlen, int __flags)
+{
+
+  /* TBD: define a new vppcom api */
+  return 0;
+}
+#endif
+
+/* TBD: move it to vppcom */
+static inline ssize_t
+vcom_session_recvmsg (int __sid, struct msghdr *__message, int __flags)
+{
+  int rv = -1;
+  /* rv = vppcom_session_read (__sid, (void *) __message->__buf,
+     (int)__n); */
+  rv = -EOPNOTSUPP;
+  return rv;
+}
+
+ssize_t
+vcom_socket_recvmsg (int __fd, struct msghdr * __message, int __flags)
+{
+  int rv = -1;
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  uword *p;
+  vcom_socket_t *vsock;
+
+  p = hash_get (vsm->sockidx_by_fd, __fd);
+  if (!p)
+    return -EBADF;
+
+  vsock = pool_elt_at_index (vsm->vsockets, p[0]);
+  if (!vsock)
+    return -ENOTSOCK;
+
+  if (vsock->type != SOCKET_TYPE_VPPCOM_BOUND)
+    return -EINVAL;
+
+  if (!__message)
+    {
+      return -EINVAL;
+    }
+
+  /* validate __flags */
+
+  rv = vcom_session_recvmsg (vsock->sid, __message, __flags);
+  return rv;
+}
+
+#ifdef __USE_GNU
+int
+vcom_socket_recvmmsg (int __fd, struct mmsghdr *__vmessages,
+		      unsigned int __vlen, int __flags,
+		      struct timespec *__tmo)
+{
+  /* TBD: define a new vppcom api */
+  return 0;
+}
+#endif
+
+/* TBD: move it to vppcom */
+static inline int
+vcom_session_get_sockopt (int __sid, int __level, int __optname,
+			  void *__restrict __optval,
+			  socklen_t * __restrict __optlen)
+{
+  /* 1. for socket level options that are NOT socket attributes
+   *    and that has corresponding vpp options get from vppcom */
+  return 0;
+}
+
+int
+vcom_socket_getsockopt (int __fd, int __level, int __optname,
+			void *__restrict __optval,
+			socklen_t * __restrict __optlen)
+{
+  int rv = -1;
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  uword *p;
+  vcom_socket_t *vsock;
+
+  p = hash_get (vsm->sockidx_by_fd, __fd);
+  if (!p)
+    return -EBADF;
+
+  vsock = pool_elt_at_index (vsm->vsockets, p[0]);
+  if (!vsock)
+    return -ENOTSOCK;
+
+  if (vsock->type != SOCKET_TYPE_VPPCOM_BOUND)
+    return -EINVAL;
+
+  if (!__optval && !__optlen)
+    return -EFAULT;
+
+  switch (__level)
+    {
+      /* handle options at socket level */
+    case SOL_SOCKET:
+      switch (__optname)
+	{
+/*
+ *  1. for socket level options that are socket attributes,
+ *     get from libc_getsockopt.
+ *  2. for socket level options that are NOT socket
+ *     attributes and that has corresponding vpp options
+ *     get from vppcom.
+ *  3. for socket level options unimplemented
+ *     return -ENOPROTOOPT */
+	case SO_DEBUG:
+	case SO_DONTROUTE:
+	case SO_BROADCAST:
+	case SO_SNDBUF:
+	case SO_RCVBUF:
+	case SO_REUSEADDR:
+	case SO_REUSEPORT:
+	case SO_KEEPALIVE:
+	case SO_TYPE:
+	case SO_PROTOCOL:
+	case SO_DOMAIN:
+	case SO_ERROR:
+	case SO_OOBINLINE:
+	case SO_NO_CHECK:
+	case SO_PRIORITY:
+	case SO_LINGER:
+	case SO_BSDCOMPAT:
+	case SO_TIMESTAMP:
+	case SO_TIMESTAMPNS:
+	case SO_TIMESTAMPING:
+	case SO_RCVTIMEO:
+	case SO_SNDTIMEO:
+	case SO_RCVLOWAT:
+	case SO_SNDLOWAT:
+	case SO_PASSCRED:
+	case SO_PEERCRED:
+	case SO_PEERNAME:
+	case SO_ACCEPTCONN:
+	case SO_PASSSEC:
+	case SO_PEERSEC:
+	case SO_MARK:
+	case SO_RXQ_OVFL:
+	case SO_WIFI_STATUS:
+	case SO_PEEK_OFF:
+	case SO_NOFCS:
+	case SO_BINDTODEVICE:
+	case SO_GET_FILTER:
+	case SO_LOCK_FILTER:
+	case SO_BPF_EXTENSIONS:
+	case SO_SELECT_ERR_QUEUE:
+#ifdef CONFIG_NET_RX_BUSY_POLL
+	case SO_BUSY_POLL:
+#endif
+	case SO_MAX_PACING_RATE:
+#ifdef SO_INCOMING_CPU
+	case SO_INCOMING_CPU:
+#endif
+	  rv = libc_getsockopt (__fd, __level, __optname, __optval, __optlen);
+	  if (rv != 0)
+	    {
+	      rv = -errno;
+	      return rv;
+	    }
+	  break;
+
+	default:
+	  /* We implement the SO_SNDLOWAT etc to not be settable
+	   * (1003.1g 7).
+	   */
+	  return -ENOPROTOOPT;
+	}
+
+      break;
+
+    default:
+      /* 1. handle options that are NOT socket level options,
+       *    but have corresponding vpp otions. */
+      rv = vcom_session_get_sockopt (vsock->sid, __level, __optname,
+				     __optval, __optlen);
+      break;
+    }
+
+  return rv;
+}
+
+/* TBD: move it to vppcom */
+static inline int
+vcom_session_setsockopt (int __sid, int __level, int __optname,
+			 const void *__optval, socklen_t __optlen)
+{
+  int rv = -EOPNOTSUPP;
+
+  switch (__level)
+    {
+    case SOL_TCP:
+      switch (__optname)
+	{
+	case TCP_KEEPIDLE:
+	  rv =
+	    vppcom_session_attr (__sid, VPPCOM_ATTR_SET_TCP_KEEPIDLE, 0, 0);
+	  break;
+	case TCP_KEEPINTVL:
+	  rv =
+	    vppcom_session_attr (__sid, VPPCOM_ATTR_SET_TCP_KEEPINTVL, 0, 0);
+	  break;
+	default:
+	  break;
+	}
+      break;
+    case SOL_IPV6:
+      switch (__optname)
+	{
+	case IPV6_V6ONLY:
+	  rv = vppcom_session_attr (__sid, VPPCOM_ATTR_SET_V6ONLY, 0, 0);
+	  break;
+	default:
+	  break;
+	}
+      break;
+    case SOL_SOCKET:
+      switch (__optname)
+	{
+	case SO_KEEPALIVE:
+	  rv = vppcom_session_attr (__sid, VPPCOM_ATTR_SET_KEEPALIVE, 0, 0);
+	  break;
+	case SO_REUSEADDR:
+	  rv = vppcom_session_attr (__sid, VPPCOM_ATTR_SET_REUSEADDR, 0, 0);
+	  break;
+	case SO_BROADCAST:
+	  rv = vppcom_session_attr (__sid, VPPCOM_ATTR_SET_BROADCAST, 0, 0);
+	  break;
+	default:
+	  break;
+	}
+      break;
+    default:
+      break;
+    }
+
+  return rv;
+}
+
+int
+vcom_socket_setsockopt (int __fd, int __level, int __optname,
+			const void *__optval, socklen_t __optlen)
+{
+  int rv = -1;
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  uword *p;
+  vcom_socket_t *vsock;
+
+  p = hash_get (vsm->sockidx_by_fd, __fd);
+  if (!p)
+    return -EBADF;
+
+  vsock = pool_elt_at_index (vsm->vsockets, p[0]);
+  if (!vsock)
+    return -ENOTSOCK;
+
+  if (vsock->type != SOCKET_TYPE_VPPCOM_BOUND)
+    return -EINVAL;
+
+  /*
+   *      Options without arguments
+   */
+
+  if (__optname == SO_BINDTODEVICE)
+    {
+      rv = libc_setsockopt (__fd, __level, __optname, __optval, __optlen);
+      if (rv != 0)
+	{
+	  rv = -errno;
+	}
+      return rv;
+    }
+
+  if (!__optval)
+    return -EFAULT;
+
+  if (__optlen < sizeof (int))
+    return -EINVAL;
+
+  switch (__level)
+    {
+    case SOL_IPV6:
+      switch (__optname)
+	{
+	case IPV6_V6ONLY:
+	  rv = vcom_session_setsockopt (vsock->sid, __level, __optname,
+					__optval, __optlen);
+	  break;
+	default:
+	  return -EOPNOTSUPP;
+	}
+      break;
+    case SOL_TCP:
+      switch (__optname)
+	{
+	case TCP_NODELAY:
+	  return 0;
+	case TCP_KEEPIDLE:
+	case TCP_KEEPINTVL:
+	  rv = vcom_session_setsockopt (vsock->sid, __level, __optname,
+					__optval, __optlen);
+	  break;
+	default:
+	  return -EOPNOTSUPP;
+	}
+      break;
+      /* handle options at socket level */
+    case SOL_SOCKET:
+      switch (__optname)
+	{
+	case SO_REUSEADDR:
+	case SO_BROADCAST:
+	case SO_KEEPALIVE:
+	  rv = vcom_session_setsockopt (vsock->sid, __level, __optname,
+					__optval, __optlen);
+	  break;
+
+	  /*
+	   * 1. for socket level options that are socket attributes,
+	   *    set it from libc_getsockopt
+	   * 2. for socket level options that are NOT socket
+	   *    attributes and that has corresponding vpp options
+	   *    set it from vppcom
+	   * 3. for socket level options unimplemented
+	   *    return -ENOPROTOOPT */
+	case SO_DEBUG:
+	case SO_DONTROUTE:
+	case SO_SNDBUF:
+	case SO_RCVBUF:
+	case SO_REUSEPORT:
+	case SO_TYPE:
+	case SO_PROTOCOL:
+	case SO_DOMAIN:
+	case SO_ERROR:
+	case SO_OOBINLINE:
+	case SO_NO_CHECK:
+	case SO_PRIORITY:
+	case SO_LINGER:
+	case SO_BSDCOMPAT:
+	case SO_TIMESTAMP:
+	case SO_TIMESTAMPNS:
+	case SO_TIMESTAMPING:
+	case SO_RCVTIMEO:
+	case SO_SNDTIMEO:
+	case SO_RCVLOWAT:
+	case SO_SNDLOWAT:
+	case SO_PASSCRED:
+	case SO_PEERCRED:
+	case SO_PEERNAME:
+	case SO_ACCEPTCONN:
+	case SO_PASSSEC:
+	case SO_PEERSEC:
+	case SO_MARK:
+	case SO_RXQ_OVFL:
+	case SO_WIFI_STATUS:
+	case SO_PEEK_OFF:
+	case SO_NOFCS:
+	  /*
+	   * SO_BINDTODEVICE already handled as
+	   * "Options without arguments" */
+	  /* case SO_BINDTODEVICE: */
+	case SO_GET_FILTER:
+	case SO_LOCK_FILTER:
+	case SO_BPF_EXTENSIONS:
+	case SO_SELECT_ERR_QUEUE:
+#ifdef CONFIG_NET_RX_BUSY_POLL
+	case SO_BUSY_POLL:
+#endif
+	case SO_MAX_PACING_RATE:
+#ifdef SO_INCOMING_CPU
+	case SO_INCOMING_CPU:
+#endif
+	  rv = libc_setsockopt (__fd, __level, __optname, __optval, __optlen);
+	  if (rv != 0)
+	    {
+	      rv = -errno;
+	      return rv;
+	    }
+	  break;
+
+	default:
+	  /* We implement the SO_SNDLOWAT etc to not be settable
+	   * (1003.1g 7).
+	   */
+	  return -ENOPROTOOPT;
+	}
+
+      break;
+
+    default:
+      return -ENOPROTOOPT;
+    }
+
+  return rv;
+}
+
+int
+vcom_socket_listen (int __fd, int __n)
+{
+  int rv = -1;
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  uword *p;
+  vcom_socket_t *vsock;
+
+  p = hash_get (vsm->sockidx_by_fd, __fd);
+  if (p)
+    {
+      vsock = pool_elt_at_index (vsm->vsockets, p[0]);
+
+      /* TBD vppcom to accept __n parameter */
+      rv = vppcom_session_listen (vsock->sid, __n);
+    }
+
+  return rv;
+}
+
+static int
+vcom_socket_connected_socket (int __fd, int __sid,
+			      int *__domain,
+			      int *__type, int *__protocol, int flags)
+{
+  int rv = -1;
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  vcom_socket_t *vsock;
+
+  i32 fd;
+  i32 sockidx;
+
+  socklen_t optlen;
+
+  optlen = sizeof (*__domain);
+  rv = libc_getsockopt (__fd, SOL_SOCKET, SO_DOMAIN, __domain, &optlen);
+  if (rv != 0)
+    {
+      rv = -errno;
+      goto out;
+    }
+
+  optlen = sizeof (*__type);
+  rv = libc_getsockopt (__fd, SOL_SOCKET, SO_TYPE, __type, &optlen);
+  if (rv != 0)
+    {
+      rv = -errno;
+      goto out;
+    }
+
+  optlen = sizeof (*__protocol);
+  rv = libc_getsockopt (__fd, SOL_SOCKET, SO_PROTOCOL, __protocol, &optlen);
+  if (rv != 0)
+    {
+      rv = -errno;
+      goto out;
+    }
+
+  fd = vcom_socket_open_socket (*__domain, *__type | flags, *__protocol);
+  if (fd < 0)
+    {
+      rv = fd;
+      goto out;
+    }
+
+  pool_get (vsm->vsockets, vsock);
+  vsocket_init (vsock);
+
+  sockidx = vsock - vsm->vsockets;
+  hash_set (vsm->sockidx_by_fd, fd, sockidx);
+
+  vsocket_set (vsock, fd, __sid, SOCKET_TYPE_VPPCOM_BOUND);
+  return fd;
+
+out:
+  return rv;
+}
+
+/* If flag is 0, then accept4() is the same as accept().
+ * SOCK_NONBLOCK and SOCK_CLOEXEC can be bitwise ORed in flags
+ */
+static int
+vcom_socket_accept_flags (int __fd, __SOCKADDR_ARG __addr,
+			  socklen_t * __restrict __addr_len, int flags)
+{
+  int rv = -1;
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  uword *p;
+  vcom_socket_t *vsock;
+
+  int fd;
+  int sid;
+  int domain;
+  int type;
+  int protocol;
+
+  uint8_t addr8[sizeof (struct in6_addr)];
+  vppcom_endpt_t ep;
+
+  ep.ip = addr8;
+
+  /* validate flags */
+
+  /*
+   * for documentation
+   *  switch (flags)
+   *   {
+   *   case 0:
+   *   case SOCK_NONBLOCK:
+   *   case SOCK_CLOEXEC:
+   *   case SOCK_NONBLOCK | SOCK_CLOEXEC:
+   *     break;
+   *
+   *   default:
+   *     return -1;
+   *   }
+   */
+  /* flags can be 0 or can be bitwise OR
+   * of any of SOCK_NONBLOCK and SOCK_CLOEXEC */
+
+  if (!(!flags || (flags & (SOCK_NONBLOCK | SOCK_CLOEXEC))))
+    {
+      /* TBD: return proper error code */
+      return -1;
+    }
+
+  /* TBD: return proper error code */
+
+  if (!vcom_socket_is_connection_mode_socket (__fd))
+    {
+      return -EOPNOTSUPP;
+    }
+
+  p = hash_get (vsm->sockidx_by_fd, __fd);
+  if (p)
+    {
+      vsock = pool_elt_at_index (vsm->vsockets, p[0]);
+
+
+      rv = vcom_fcntl (vsock->fd, F_GETFL, 0);
+      if (rv < 0)
+	{
+	  return rv;
+	}
+
+      /* is blocking */
+      if (!(rv & O_NONBLOCK))
+	{
+	  /* socket is not marked as nonblocking
+	   * and no pending connections are present
+	   * on the queue, accept () blocks the caller
+	   * until a connection is present.
+	   */
+	  rv = vppcom_session_accept (vsock->sid, &ep,
+				      -1.0 /* wait forever */ );
+	}
+      else
+	{
+	  /* The file descriptor refers to a socket and has been
+	   * marked nonblocking(O_NONBLOCK) and the accept would
+	   * block.
+	   * */
+	  /* is non blocking */
+	  rv = vppcom_session_accept (vsock->sid, &ep, 0);
+	  /* If the socket is marked nonblocking and
+	   * no pending connections are present on the
+	   * queue, accept fails with the error
+	   * EAGAIN or EWOULDBLOCK
+	   */
+	  if (rv == VPPCOM_ETIMEDOUT)
+	    {
+	      rv = VPPCOM_EAGAIN;
+	    }
+	}
+      if (rv < 0)
+	{
+	  return rv;
+	}
+
+      sid = rv;
+
+      /* create a new connected socket resource and set flags
+       * on the new file descriptor.
+       * update vsockets and sockidx_by_fd table
+       * */
+      fd = vcom_socket_connected_socket (__fd, sid,
+					 &domain, &type, &protocol, flags);
+      if (fd < 0)
+	{
+	  return fd;
+	}
+
+      rv = fd;
+
+      /* TBD populate __addr and __addr_len */
+      /* TBD: The returned address is truncated if the buffer
+       * provided is too small, in this case, __addr_len will
+       * return a value greater than was supplied to the call.*/
+      if (__addr)
+	{
+	  if (ep.is_cut_thru)
+	    {
+	      /* TBD populate __addr and __addr_len */
+	      switch (domain)
+		{
+		case AF_INET:
+		  ((struct sockaddr_in *) __addr)->sin_family = AF_INET;
+		  ((struct sockaddr_in *) __addr)->sin_port = ep.port;
+		  memcpy (&((struct sockaddr_in *) __addr)->sin_addr,
+			  addr8, sizeof (struct in_addr));
+		  /* TBD: populate __addr_len */
+		  if (__addr_len)
+		    {
+		      *__addr_len = sizeof (struct sockaddr_in);
+		    }
+		  break;
+
+		case AF_INET6:
+		  ((struct sockaddr_in6 *) __addr)->sin6_family = AF_INET6;
+		  ((struct sockaddr_in6 *) __addr)->sin6_port = ep.port;
+		  memcpy (((struct sockaddr_in6 *) __addr)->sin6_addr.
+			  __in6_u.__u6_addr8, addr8,
+			  sizeof (struct in6_addr));
+		  /* TBD: populate __addr_len */
+		  if (__addr_len)
+		    {
+		      *__addr_len = sizeof (struct sockaddr_in6);
+		    }
+		  break;
+
+		default:
+		  return -EAFNOSUPPORT;
+		}
+	    }
+	  else
+	    {
+	      switch (ep.is_ip4)
+		{
+		case VPPCOM_IS_IP4:
+		  ((struct sockaddr_in *) __addr)->sin_family = AF_INET;
+		  ((struct sockaddr_in *) __addr)->sin_port = ep.port;
+		  memcpy (&((struct sockaddr_in *) __addr)->sin_addr,
+			  addr8, sizeof (struct in_addr));
+		  /* TBD: populate __addr_len */
+		  if (__addr_len)
+		    {
+		      *__addr_len = sizeof (struct sockaddr_in);
+		    }
+		  break;
+
+		case VPPCOM_IS_IP6:
+		  ((struct sockaddr_in6 *) __addr)->sin6_family = AF_INET6;
+		  ((struct sockaddr_in6 *) __addr)->sin6_port = ep.port;
+		  memcpy (((struct sockaddr_in6 *) __addr)->sin6_addr.
+			  __in6_u.__u6_addr8, addr8,
+			  sizeof (struct in6_addr));
+		  /* TBD: populate __addr_len */
+		  if (__addr_len)
+		    {
+		      *__addr_len = sizeof (struct sockaddr_in6);
+		    }
+		  break;
+
+		default:
+		  return -EAFNOSUPPORT;
+		}
+	    }
+	}
+      else
+	{
+	  /* when __addr is NULL, nothing is filled in,
+	   * in this case, __addr_len is not used,
+	   * and should also be null
+	   * */
+	  if (__addr_len)
+	    {
+	      /* TBD: return proper error code */
+	      return -1;
+	    }
+	}
+    }
+
+  return rv;
+}
+
+int
+vcom_socket_accept (int __fd, __SOCKADDR_ARG __addr,
+		    socklen_t * __restrict __addr_len)
+{
+  /* set flags to 0 for accept() */
+  return vcom_socket_accept_flags (__fd, __addr, __addr_len, 0);
+}
+
+#ifdef __USE_GNU
+int
+vcom_socket_accept4 (int __fd, __SOCKADDR_ARG __addr,
+		     socklen_t * __restrict __addr_len, int __flags)
+{
+  /*  SOCK_NONBLOCK and SOCK_CLOEXEC can be bitwise ORed in flags */
+  return vcom_socket_accept_flags (__fd, __addr, __addr_len, __flags);
+}
+#endif
+
+/* TBD: move it to vppcom */
+static inline int
+vcom_session_shutdown (int __fd, int __how)
+{
+  return 0;
+}
+
+int
+vcom_socket_shutdown (int __fd, int __how)
+{
+  int rv = -1;
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  uword *p;
+  vcom_socket_t *vsock;
+
+  p = hash_get (vsm->sockidx_by_fd, __fd);
+  if (p)
+    {
+      vsock = pool_elt_at_index (vsm->vsockets, p[0]);
+      switch (__how)
+	{
+	case SHUT_RD:
+	case SHUT_WR:
+	case SHUT_RDWR:
+	  rv = vcom_session_shutdown (vsock->sid, __how);
+	  return rv;
+	  break;
+
+	default:
+	  return -EINVAL;
+	  break;
+	}
+    }
+
+  return rv;
+}
+
+int
+vcom_socket_epoll_create1 (int __flags)
+{
+  int rv = -1;
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  vcom_epoll_t *vepoll;
+
+  i32 epfd;
+  i32 vep_idx;
+  i32 epollidx;
+
+  epfd = vcom_socket_open_epoll (__flags);
+  if (epfd < 0)
+    {
+      rv = epfd;
+      goto out;
+    }
+
+  vep_idx = vppcom_epoll_create ();
+  if (vep_idx < 0)
+    {
+      rv = vep_idx;
+      goto out_close_epoll;
+    }
+
+  pool_get (vsm->vepolls, vepoll);
+  vepoll_init (vepoll);
+
+  epollidx = vepoll - vsm->vepolls;
+  hash_set (vsm->epollidx_by_epfd, epfd, epollidx);
+
+  vepoll_set (vepoll, epfd, vep_idx, EPOLL_TYPE_VPPCOM_BOUND, __flags, 0, 0);
+
+  return epfd;
+
+out_close_epoll:
+  vcom_socket_close_epoll (epfd);
+out:
+  return rv;
+}
+
+/*
+ * PRE: vppcom_epoll_ctl() is successful
+ * free_vepitem_on_del : 0 - no_pool_put, 1 - pool_put
+ */
+int
+vcom_socket_ctl_vepitem (int __epfd, int __op, int __fd,
+			 struct epoll_event *__event,
+			 i32 vep_idx, vcom_epoll_t * vepoll,
+			 i32 vfd_id, void *vfd, vcom_fd_type_t type,
+			 int free_vepitem_on_del)
+{
+  int rv = -1;
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  vcom_epitem_t *vepitem;
+
+  vcom_epitem_key_t epfdfd = {.epfd = __epfd,.fd = __fd };
+  uword *p;
+  i32 vepitemidx;
+
+  i32 *vepitemidxs = 0;
+
+  struct epoll_event revent = {.events = 0,.data.fd = INVALID_FD };
+
+  i32 vec_idx;
+
+  /* perform control operations on the epoll instance */
+  switch (__op)
+    {
+    case EPOLL_CTL_ADD:
+      /*
+       * supplied file descriptor is already
+       * registered with this epoll instance
+       * */
+      /* vepitem exists */
+      p = hash_get (vsm->epitemidx_by_epfdfd, epfdfd.key);
+      if (p)
+	{
+	  rv = -EEXIST;
+	  goto out;
+	}
+
+      /* add a new vepitem */
+      pool_get (vsm->vepitems, vepitem);
+      vepitem_init (vepitem);
+
+      vepitemidx = vepitem - vsm->vepitems;
+      hash_set (vsm->epitemidx_by_epfdfd, epfdfd.key, vepitemidx);
+      vepitem_set (vepitem, __epfd, __fd, __fd, __fd, type, *__event, revent);
+
+      /* update epitemidxs */
+      /* by_epfd */
+      p = hash_get (vsm->epitemidxs_by_epfd, __epfd);
+      if (!p)			/*  not exist */
+	{
+	  vepitemidxs = 0;
+	  vec_add1 (vepitemidxs, vepitemidx);
+	  hash_set (vsm->epitemidxs_by_epfd, __epfd, vepitemidxs);
+	}
+      else			/*  exists */
+	{
+	  vepitemidxs = *(i32 **) p;
+	  vec_add1 (vepitemidxs, vepitemidx);
+	  hash_set3 (vsm->epitemidxs_by_epfd, __epfd, vepitemidxs, 0);
+	}
+      /* update epitemidxs */
+      /* by_fd */
+      p = hash_get (vsm->epitemidxs_by_fd, __fd);
+      if (!p)			/*  not exist */
+	{
+	  vepitemidxs = 0;
+	  vec_add1 (vepitemidxs, vepitemidx);
+	  hash_set (vsm->epitemidxs_by_fd, __fd, vepitemidxs);
+	}
+      else			/*  exists */
+	{
+	  vepitemidxs = *(i32 **) p;
+	  vec_add1 (vepitemidxs, vepitemidx);
+	  hash_set3 (vsm->epitemidxs_by_fd, __fd, vepitemidxs, 0);
+	}
+
+      /* increment vepoll fd count by 1 */
+      vepoll->count += 1;
+
+      rv = 0;
+      goto out;
+      break;
+
+    case EPOLL_CTL_MOD:
+      /*
+       * supplied file descriptor is not
+       * registered with this epoll instance
+       * */
+      /* vepitem not exist */
+      p = hash_get (vsm->epitemidx_by_epfdfd, epfdfd.key);
+      if (!p)
+	{
+	  rv = -ENOENT;
+	  goto out;
+	}
+      vepitem = pool_elt_at_index (vsm->vepitems, p[0]);
+      if (vepitem)
+	{
+	  vepitem->event = *__event;
+	  vepitem->revent = revent;
+	}
+
+      rv = 0;
+      goto out;
+      break;
+
+    case EPOLL_CTL_DEL:
+      /*
+       * supplied file descriptor is not
+       * registered with this epoll instance
+       * */
+      /* vepitem not exist */
+      p = hash_get (vsm->epitemidx_by_epfdfd, epfdfd.key);
+      if (!p)
+	{
+	  rv = -ENOENT;
+	  goto out;
+	}
+      vepitemidx = *(i32 *) p;
+      hash_unset (vsm->epitemidx_by_epfdfd, epfdfd.key);
+
+      /* update epitemidxs */
+      /* by_epfd */
+      p = hash_get (vsm->epitemidxs_by_epfd, __epfd);
+      if (!p)			/*  not exist */
+	{
+	  rv = -ENOENT;
+	  goto out;
+	}
+      else			/*  exists */
+	{
+	  vepitemidxs = *(i32 **) p;
+	  vec_idx = vec_search (vepitemidxs, vepitemidx);
+	  if (vec_idx != ~0)
+	    {
+	      vec_del1 (vepitemidxs, vec_idx);
+	      if (!vec_len (vepitemidxs))
+		{
+		  vec_free (vepitemidxs);
+		  hash_unset (vsm->epitemidxs_by_epfd, __epfd);
+		}
+	    }
+	}
+
+      /* update epitemidxs */
+      /* by_fd */
+      p = hash_get (vsm->epitemidxs_by_fd, __fd);
+      if (!p)			/*  not exist */
+	{
+	  rv = -ENOENT;
+	  goto out;
+	}
+      else			/*  exists */
+	{
+	  vepitemidxs = *(i32 **) p;
+	  vec_idx = vec_search (vepitemidxs, vepitemidx);
+	  if (vec_idx != ~0)
+	    {
+	      vec_del1 (vepitemidxs, vec_idx);
+	      if (!vec_len (vepitemidxs))
+		{
+		  vec_free (vepitemidxs);
+		  hash_unset (vsm->epitemidxs_by_fd, __fd);
+		}
+	    }
+	}
+
+      /* pool put vepitem */
+      vepitem = pool_elt_at_index (vsm->vepitems, vepitemidx);
+      if (free_vepitem_on_del)
+	{
+	  if (!vepitem)
+	    {
+	      rv = -ENOENT;
+	      goto out;
+	    }
+	  vepitem_init (vepitem);
+	  pool_put (vsm->vepitems, vepitem);
+	}
+      else
+	{
+	  if (!vepitem)
+	    {
+	      vepitem_init (vepitem);
+	    }
+	}
+
+      /* decrement vepoll fd count by 1 */
+      vepoll->count -= 1;
+
+      rv = 0;
+      goto out;
+      break;
+
+    default:
+      rv = -EINVAL;
+      goto out;
+      break;
+    }
+
+out:
+  return rv;
+}
+
+/*
+ * PRE: 00. null pointer check on __event
+ *      01. all other parameters are validated
+ */
+
+static int
+vcom_socket_epoll_ctl_internal (int __epfd, int __op, int __fd,
+				struct epoll_event *__event,
+				int free_vepitem_on_del)
+{
+  int rv = -1;
+
+  /* vcom_socket_main_t *vsm = &vcom_socket_main; */
+  vcom_epoll_t *vepoll;
+
+  /*__fd could could be vcom socket or vcom epoll or kernel fd */
+  void *vfd;
+  vcom_epoll_t *vfd_vepoll;
+  vcom_socket_t *vfd_vsock;
+
+  i32 vep_idx;
+  i32 vfd_id;
+
+  vcom_fd_type_t type = FD_TYPE_INVALID;
+
+  /* validate __event */
+
+  /* get vep_idx and vepoll */
+  vep_idx = vcom_socket_get_vep_idx_and_vepoll (__epfd, &vepoll);
+  if (vep_idx == INVALID_VEP_IDX)
+    {
+      return -EBADF;
+    }
+
+  /* get vcom fd type, vfd_id and vfd */
+  vfd_id = vcom_socket_get_sid_and_vsock (__fd, &vfd_vsock);
+  if (vfd_id != INVALID_SESSION_ID)
+    {
+      type = FD_TYPE_VCOM_SOCKET;
+      vfd = vfd_vsock;
+    }
+  else if ((vfd_id = vcom_socket_get_vep_idx_and_vepoll (__fd, &vfd_vepoll))
+	   != INVALID_VEP_IDX)
+    {
+      type = FD_TYPE_EPOLL;
+      vfd = vfd_vepoll;
+    }
+  else
+    {
+      /* FD_TYPE_KERNEL not supported by epoll instance */
+      type = FD_TYPE_INVALID;
+      return -EBADF;
+    }
+
+
+  /* vepoll and vsock are now valid */
+  rv = vppcom_epoll_ctl (vep_idx, __op, vfd_id, __event);
+  if (rv < 0)
+    {
+      return rv;
+    }
+
+  rv = vcom_socket_ctl_vepitem (__epfd, __op, __fd,
+				__event,
+				vep_idx, vepoll,
+				vfd_id, vfd, type, free_vepitem_on_del);
+  return rv;
+}
+
+int
+vcom_socket_epoll_ctl (int __epfd, int __op, int __fd,
+		       struct epoll_event *__event)
+{
+  int rv = -1;
+
+  rv = vcom_socket_epoll_ctl_internal (__epfd, __op, __fd, __event, 1);
+  return rv;
+}
+
+static int
+vcom_socket_epoll_ctl1 (int __epfd, int __op, int __fd,
+			struct epoll_event *__event)
+{
+  int rv = -1;
+
+  rv = vcom_socket_epoll_ctl_internal (__epfd, __op, __fd, __event, 0);
+  return rv;
+}
+
+int
+vcom_socket_epoll_pwait (int __epfd, struct epoll_event *__events,
+			 int __maxevents, int __timeout,
+			 const __sigset_t * __ss)
+{
+  int rv = -EBADF;
+
+  /* in seconds eg. 3.123456789 seconds */
+  double time_to_wait = (double) 0;
+
+  i32 vep_idx;
+
+  /* validate __event */
+  if (!__events)
+    {
+      rv = -EFAULT;
+      goto out;
+    }
+
+  /* validate __timeout */
+  if (__timeout > 0)
+    {
+      time_to_wait = (double) __timeout / (double) 1000;
+    }
+  else if (__timeout == 0)
+    {
+      time_to_wait = (double) 0;
+    }
+  else if (__timeout == -1)
+    {
+      time_to_wait = ~0;
+    }
+  else
+    {
+      rv = -EBADF;
+      goto out;
+    }
+
+  /* get vep_idx */
+  vep_idx = vcom_socket_get_vep_idx (__epfd);
+  if (vep_idx != INVALID_VEP_IDX)
+    {
+      rv = vppcom_epoll_wait (vep_idx, __events, __maxevents, time_to_wait);
+    }
+out:
+  return rv;
+}
+
+static inline void
+vcom_pollfds_2_selectfds (
+			   /* src */
+			   struct pollfd *__fds, nfds_t __nfds,
+			   /* dest */
+			   int vcom_nfds,
+			   fd_set * __restrict vcom_readfds,
+			   fd_set * __restrict vcom_writefds,
+			   fd_set * __restrict vcom_exceptfds)
+{
+  nfds_t fds_idx = 0;
+
+  for (fds_idx = 0; fds_idx < __nfds; fds_idx++)
+    {
+      /* ignore negative fds */
+      if (__fds[fds_idx].fd < 0)
+	{
+	  continue;
+	}
+
+      /* for POLLRDHUP, POLLERR, POLLHUP and  POLLNVAL */
+      FD_SET (__fds[fds_idx].fd, vcom_exceptfds);
+
+      /* requested events */
+      if (__fds[fds_idx].events)
+	{
+	  if (__fds[fds_idx].events & POLLIN)
+	    {
+	      FD_SET (__fds[fds_idx].fd, vcom_readfds);
+	    }
+	  if (__fds[fds_idx].events & POLLPRI)
+	    {
+	      FD_SET (__fds[fds_idx].fd, vcom_readfds);
+	    }
+	  if (__fds[fds_idx].events & POLLOUT)
+	    {
+	      FD_SET (__fds[fds_idx].fd, vcom_writefds);
+	    }
+#if defined __USE_XOPEN || defined __USE_XOPEN2K8
+	  if (__fds[fds_idx].events & POLLRDNORM)
+	    {
+	      FD_SET (__fds[fds_idx].fd, vcom_readfds);
+	    }
+	  if (__fds[fds_idx].events & POLLRDBAND)
+	    {
+	      FD_SET (__fds[fds_idx].fd, vcom_readfds);
+	    }
+	  if (__fds[fds_idx].events & POLLWRNORM)
+	    {
+	      FD_SET (__fds[fds_idx].fd, vcom_writefds);
+	    }
+	  if (__fds[fds_idx].events & POLLWRBAND)
+	    {
+	      FD_SET (__fds[fds_idx].fd, vcom_writefds);
+	    }
+#endif
+	}
+    }				/* for (fds_idx = 0; fds_idx < __nfds; fds_idx++) */
+}
+
+static inline void
+vcom_selectfds_2_pollfds (
+			   /* dest */
+			   struct pollfd *__fds, nfds_t __nfds, int *nfd,
+			   /* src */
+			   int vcom_nfds,
+			   fd_set * __restrict vcom_readfds,
+			   fd_set * __restrict vcom_writefds,
+			   fd_set * __restrict vcom_exceptfds)
+{
+  nfds_t fds_idx = 0;
+
+
+  for (fds_idx = 0; fds_idx < __nfds; fds_idx++)
+    {
+      /* ignore negative fds */
+      if (__fds[fds_idx].fd < 0)
+	{
+	  __fds[fds_idx].revents = 0;
+	}
+
+      /* for POLLRDHUP, POLLERR, POLLHUP and  POLLNVAL */
+      if (FD_ISSET (__fds[fds_idx].fd, vcom_exceptfds))
+	{
+	  /*
+	   * TBD: for now any select exception
+	   *      is flagged as POLLERR
+	   * */
+	  __fds[fds_idx].revents |= POLLERR;
+	}
+
+      /* requested events */
+      if (__fds[fds_idx].events & POLLIN)
+	{
+	  if (FD_ISSET (__fds[fds_idx].fd, vcom_readfds))
+	    {
+	      __fds[fds_idx].revents |= POLLIN;
+	    }
+	}
+      if (__fds[fds_idx].events & POLLPRI)
+	{
+	  if (FD_ISSET (__fds[fds_idx].fd, vcom_readfds))
+	    {
+	      __fds[fds_idx].revents |= POLLIN;
+	    }
+	}
+      if (__fds[fds_idx].events & POLLOUT)
+	{
+	  if (FD_ISSET (__fds[fds_idx].fd, vcom_writefds))
+	    {
+	      __fds[fds_idx].revents |= POLLOUT;
+	    }
+	}
+#if defined __USE_XOPEN || defined __USE_XOPEN2K8
+      if (__fds[fds_idx].events & POLLRDNORM)
+	{
+	  if (FD_ISSET (__fds[fds_idx].fd, vcom_readfds))
+	    {
+	      __fds[fds_idx].revents |= POLLRDNORM;
+	    }
+	}
+      if (__fds[fds_idx].events & POLLRDBAND)
+	{
+	  if (FD_ISSET (__fds[fds_idx].fd, vcom_readfds))
+	    {
+	      __fds[fds_idx].revents |= POLLRDBAND;
+	    }
+	}
+      if (__fds[fds_idx].events & POLLWRNORM)
+	{
+	  if (FD_ISSET (__fds[fds_idx].fd, vcom_writefds))
+	    {
+	      __fds[fds_idx].revents |= POLLWRNORM;
+	    }
+	}
+      if (__fds[fds_idx].events & POLLWRBAND)
+	{
+	  if (FD_ISSET (__fds[fds_idx].fd, vcom_writefds))
+	    {
+	      __fds[fds_idx].revents |= POLLWRBAND;
+	    }
+	}
+#endif
+    }				/* for (fds_idx = 0; fds_idx < __nfds; fds_idx++) */
+
+  /*
+   * nfd:
+   * the number of structures which have nonzero revents  fields
+   * (in  other  words,  those  descriptors  with events or
+   * errors reported)
+   * */
+  *nfd = 0;
+  for (fds_idx = 0; fds_idx < __nfds; fds_idx++)
+    {
+      /* ignore negative fds */
+      if (__fds[fds_idx].fd < 0)
+	{
+	  continue;
+	}
+
+      if (__fds[fds_idx].revents)
+	{
+	  (*nfd)++;
+	}
+    }
+}
+
+/*
+ * PRE: parameters are validated,
+ *      vcom_socket_poll is always called with __timeout set to zero
+ *      hence returns immediately
+ *
+ * ACTION: handle non negative validated vcom fds and ignore rest
+ */
+
+/*
+ * implements vcom_socket_poll () interface
+ *
+ * internally uses vcom_socket_select ()
+ * to realize the behavior
+ * */
+int
+vcom_socket_poll_select_impl (struct pollfd *__fds, nfds_t __nfds,
+			      int __timeout)
+{
+  int rv;
+  pid_t pid = getpid ();
+
+  nfds_t fds_idx = 0;
+  int nfd = 0;
+
+  /* vcom */
+  int vcom_nfds = 0;
+  fd_set vcom_readfds;
+  fd_set vcom_writefds;
+  fd_set vcom_exceptfds;
+  int vcom_nfd = -1;
+  /* invalid max_vcom_fd is -1 */
+  int max_vcom_fd = -1;
+
+  /* __timeout is zero to get ready events and return immediately */
+  struct timeval tv = {.tv_sec = 0,.tv_usec = 0 };
+
+  /* validate __nfds from select perspective */
+  if (__nfds > FD_SETSIZE)
+    {
+      rv = -EINVAL;
+      goto poll_done;
+    }
+
+  /* zero vcom fd sets */
+  /*
+   * V vcom fd set
+   */
+#define _(V)      \
+    FD_ZERO ((V))
+
+  _(&vcom_readfds);
+  _(&vcom_writefds);
+  _(&vcom_exceptfds);
+#undef _
+
+  vcom_nfds = 0;
+  vcom_nfd = -1;
+
+
+  for (fds_idx = 0; fds_idx < __nfds; fds_idx++)
+    {
+      /* ignore negative fds */
+      if (__fds[fds_idx].fd < 0)
+	{
+	  continue;
+	}
+
+      /* non negative validated vcom fds */
+      if (__fds[fds_idx].fd > FD_SETSIZE)
+	{
+	  rv = -EINVAL;
+	  goto poll_done;
+	}
+
+      /* max_vcom_fd and vcom_nfd */
+      if (__fds[fds_idx].fd > max_vcom_fd)
+	{
+	  /* requested events */
+	  if (__fds[fds_idx].events)
+	    {
+	      max_vcom_fd = __fds[fds_idx].fd;
+	    }
+	}
+      ++vcom_nfd;
+    }
+
+  vcom_nfds = max_vcom_fd != -1 ? max_vcom_fd + 1 : 0;
+
+  if (!vcom_nfds)
+    {
+      rv = vcom_nfds;
+      goto poll_done;
+    }
+
+  vcom_pollfds_2_selectfds (
+			     /* src */
+			     __fds, __nfds,
+			     /* dest */
+			     vcom_nfds,
+			     &vcom_readfds, &vcom_writefds, &vcom_exceptfds);
+
+  /* select on vcom fds */
+  vcom_nfd = vcom_socket_select (vcom_nfds,
+				 &vcom_readfds,
+				 &vcom_writefds, &vcom_exceptfds, &tv);
+  if (VCOM_DEBUG > 2)
+    fprintf (stderr,
+	     "[%d] vcom_socket_select: "
+	     "'%04d'='%04d'\n", pid, vcom_nfd, vcom_nfds);
+
+  if (vcom_nfd < 0)
+    {
+      rv = vcom_nfd;
+      goto poll_done;
+    }
+
+  vcom_selectfds_2_pollfds (
+			     /* dest */
+			     __fds, __nfds, &nfd,
+			     /* src */
+			     vcom_nfds,
+			     &vcom_readfds, &vcom_writefds, &vcom_exceptfds);
+
+  rv = nfd;
+
+poll_done:
+  return rv;
+}
+
+/*
+ * TBD: remove this static function once vppcom
+ *      has an implementation in place
+ *
+ * ACTION:
+ */
+static int
+vppcom_poll (struct pollfd *__fds, nfds_t __nfds, double time_to_wait)
+{
+  return -EOPNOTSUPP;
+}
+
+int
+vcom_socket_poll_vppcom_impl (struct pollfd *__fds, nfds_t __nfds,
+			      int __timeout)
+{
+  nfds_t fds_idx = 0;
+
+  /* in seconds eg. 3.123456789 seconds */
+  double time_to_wait = (double) 0;
+
+  i32 sid;
+  i32 vep_idx;
+
+  /* replace vcom fd with session idx */
+  for (fds_idx = 0; fds_idx < __nfds; fds_idx++)
+    {
+      /* ignore negative fds */
+      if (__fds[fds_idx].fd < 0)
+	{
+	  continue;
+	}
+
+      /* non negative validated vcom fds */
+      sid = vcom_socket_get_sid (__fds[fds_idx].fd);
+      if (sid != INVALID_SESSION_ID)
+	{
+	  __fds[fds_idx].fd = sid;
+	}
+      else
+	{
+	  /* get vep_idx */
+	  vep_idx = vcom_socket_get_vep_idx (__fds[fds_idx].fd);
+	  if (vep_idx != INVALID_VEP_IDX)
+	    {
+	      __fds[fds_idx].fd = vep_idx;
+	    }
+	  else
+	    {
+	      return -EBADF;
+	    }
+	}
+    }
+
+  /* validate __timeout */
+  if (__timeout > 0)
+    {
+      time_to_wait = (double) __timeout / (double) 1000;
+    }
+  else if (__timeout == 0)
+    {
+      time_to_wait = (double) 0;
+    }
+  else if (__timeout < 0)
+    {
+      time_to_wait = ~0;
+    }
+  else
+    {
+      return -EBADF;
+    }
+
+  return vppcom_poll (__fds, __nfds, time_to_wait);
+}
+
+int
+vcom_socket_poll (struct pollfd *__fds, nfds_t __nfds, int __timeout)
+{
+  /* select an implementation */
+
+  /* return vcom_socket_poll_vppcom_impl (__fds, __nfds, __timeout); */
+  return vcom_socket_poll_select_impl (__fds, __nfds, __timeout);
+}
+
+#ifdef __USE_GNU
+int
+vcom_socket_ppoll (struct pollfd *__fds, nfds_t __nfds,
+		   const struct timespec *__timeout, const __sigset_t * __ss)
+{
+  return -EOPNOTSUPP;
+}
+#endif
+
+int
+vcom_socket_main_init (void)
+{
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+
+  if (VCOM_DEBUG > 0)
+    printf ("vcom_socket_main_init\n");
+
+  if (!vsm->init)
+    {
+      /* TBD: define FD_MAXSIZE and use it here */
+      pool_alloc (vsm->vsockets, FD_SETSIZE);
+      vsm->sockidx_by_fd = hash_create (0, sizeof (i32));
+
+      pool_alloc (vsm->vepolls, FD_SETSIZE);
+      vsm->epollidx_by_epfd = hash_create (0, sizeof (i32));
+
+      pool_alloc (vsm->vepitems, FD_SETSIZE);
+      vsm->epitemidx_by_epfdfd = hash_create (0, sizeof (i32));
+
+      vsm->epitemidxs_by_epfd = hash_create (0, sizeof (i32 *));
+      vsm->epitemidxs_by_fd = hash_create (0, sizeof (i32 *));
+
+      vsm->init = 1;
+    }
+
+  return 0;
+}
+
+
+void
+vcom_socket_main_show (void)
+{
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  vcom_socket_t *vsock;
+
+  vcom_epoll_t *vepoll;
+
+  vcom_epitem_t *vepitem;
+
+  i32 epfd;
+  i32 fd;
+  i32 *vepitemidxs, *vepitemidxs_var;
+
+  if (vsm->init)
+    {
+      /* from active list of vsockets show vsock */
+
+      /* *INDENT-OFF* */
+      pool_foreach (vsock, vsm->vsockets,
+        ({
+          printf(
+                 "fd='%04d', sid='%08x',type='%-30s'\n",
+                 vsock->fd, vsock->sid,
+                 vcom_socket_type_str (vsock->type));
+        }));
+      /* *INDENT-ON* */
+
+      /* from active list of vepolls, show vepoll */
+
+      /* *INDENT-OFF* */
+      pool_foreach (vepoll, vsm->vepolls,
+        ({
+          printf(
+                 "epfd='%04d', vep_idx='%08x', "
+                 "type='%-30s', "
+                 "flags='%d', count='%d', close='%d'\n",
+                 vepoll->epfd, vepoll->vep_idx,
+                 vcom_socket_epoll_type_str (vepoll->type),
+                 vepoll->flags, vepoll->count, vepoll->close);
+        }));
+      /* *INDENT-ON* */
+
+      /* from active list of vepitems, show vepitem */
+
+      /* *INDENT-OFF* */
+      pool_foreach (vepitem, vsm->vepitems,
+        ({
+          printf(
+                 "epfd='%04d', fd='%04d', "
+                 "next_fd='%04d', prev_fd='%04d', "
+                 "type='%-30s', "
+                 "events='%04x', revents='%04x'\n",
+                 vepitem->epfd, vepitem->fd,
+                 vepitem->next_fd, vepitem->prev_fd,
+                 vcom_socket_vcom_fd_type_str (vepitem->type),
+                 vepitem->event.events, vepitem->revent.events);
+        }));
+
+      /* *INDENT-ON* */
+
+      /* show epitemidxs for epfd */
+      /* *INDENT-OFF* */
+      hash_foreach (epfd, vepitemidxs,
+                    vsm->epitemidxs_by_epfd,
+      ({
+        printf("\n[ '%04d': ", epfd);
+        vec_foreach (vepitemidxs_var,vepitemidxs)
+        {
+          printf("'%04d' ", (int)vepitemidxs_var[0]);
+        }
+        printf("]\n");
+      }));
+      /* *INDENT-ON* */
+
+      /* show epitemidxs for fd */
+      /* *INDENT-OFF* */
+      hash_foreach (fd, vepitemidxs,
+                    vsm->epitemidxs_by_fd,
+      ({
+        printf("\n{ '%04d': ", fd);
+        vec_foreach (vepitemidxs_var,vepitemidxs)
+        {
+          printf("'%04d' ", (int)vepitemidxs_var[0]);
+        }
+        printf("}\n");
+      }));
+      /* *INDENT-ON* */
+
+    }
+}
+
+void
+vcom_socket_main_destroy (void)
+{
+  vcom_socket_main_t *vsm = &vcom_socket_main;
+  vcom_socket_t *vsock;
+
+  vcom_epoll_t *vepoll;
+
+  vcom_epitem_t *vepitem;
+
+  i32 epfd;
+  i32 fd;
+  i32 *vepitemidxs;
+
+
+  if (VCOM_DEBUG > 0)
+    printf ("vcom_socket_main_destroy\n");
+
+  if (vsm->init)
+    {
+
+      /*
+       * from active list of vepitems,
+       * remove all "vepitem" elements from the pool in a safe way
+       * */
+
+      /* *INDENT-OFF* */
+      pool_flush (vepitem, vsm->vepitems,
+        ({
+          if (vepitem->type == FD_TYPE_EPOLL || FD_TYPE_VCOM_SOCKET)
+          {
+              vcom_socket_epoll_ctl1 (vepitem->epfd, EPOLL_CTL_DEL,
+                                     vepitem->fd, NULL);
+             vepitem_init (vepitem);
+          }
+        }));
+      /* *INDENT-ON* */
+
+      pool_free (vsm->vepitems);
+      hash_free (vsm->epitemidx_by_epfdfd);
+
+      /* free vepitemidxs for each epfd */
+      /* *INDENT-OFF* */
+      hash_foreach (epfd, vepitemidxs,
+                    vsm->epitemidxs_by_epfd,
+      ({
+        vec_free (vepitemidxs);
+      }));
+      /* *INDENT-ON* */
+      hash_free (vsm->epitemidxs_by_epfd);
+
+      /* free vepitemidxs for each fd */
+      /* *INDENT-OFF* */
+      hash_foreach (fd, vepitemidxs,
+                    vsm->epitemidxs_by_fd,
+      ({
+        vec_free (vepitemidxs);
+      }));
+      /* *INDENT-ON* */
+      hash_free (vsm->epitemidxs_by_fd);
+
+
+      /*
+       * from active list of vsockets,
+       * close socket and vppcom session
+       * */
+
+      /* *INDENT-OFF* */
+      pool_foreach (vsock, vsm->vsockets,
+        ({
+          if (vsock->type == SOCKET_TYPE_VPPCOM_BOUND)
+            {
+              vppcom_session_close (vsock->sid);
+              vcom_socket_close_socket (vsock->fd);
+              vsocket_init (vsock);
+            }
+        }));
+      /* *INDENT-ON* */
+
+      /*
+       * return vsocket element to the pool
+       * */
+
+      /* *INDENT-OFF* */
+      pool_flush (vsock, vsm->vsockets,
+        ({
+          // vsocket_init(vsock);
+          ;
+        }));
+      /* *INDENT-ON* */
+
+      pool_free (vsm->vsockets);
+      hash_free (vsm->sockidx_by_fd);
+
+      /*
+       * from active list of vepolls,
+       * close epoll and vppcom_epoll
+       * */
+
+      /* *INDENT-OFF* */
+      pool_foreach (vepoll, vsm->vepolls,
+        ({
+          if (vepoll->type == EPOLL_TYPE_VPPCOM_BOUND)
+            {
+              vppcom_session_close (vepoll->vep_idx);
+              vcom_socket_close_epoll (vepoll->epfd); /* TBD: */
+              vepoll_init (vepoll);
+            }
+        }));
+      /* *INDENT-ON* */
+
+      /*
+       * return vepoll element to the pool
+       * */
+
+      /* *INDENT-OFF* */
+      pool_flush (vepoll, vsm->vepolls,
+        ({
+          // vepoll_init(vepoll);
+          ;
+        }));
+      /* *INDENT-ON* */
+
+      pool_free (vsm->vepolls);
+      hash_free (vsm->epollidx_by_epfd);
+
+      vsm->init = 0;
+    }
+}
+
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */