memif: complete refactor of socket handling code

Change-Id: I4d41def83a23f13701f1ddcea722d481e4c85cbc
Signed-off-by: Damjan Marion <damarion@cisco.com>

1 files changed, 736 insertions, 0 deletions

diff --git a/src/plugins/memif/socket.c b/src/plugins/memif/socket.c
new file mode 100644
index 00000000000..d1a96db361e
--- /dev/null
+++ b/src/plugins/memif/socket.c
@@ -0,0 +1,736 @@
+/*
+ *------------------------------------------------------------------
+ * 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.
+ *------------------------------------------------------------------
+ */
+
+#define _GNU_SOURCE
+#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 <sys/eventfd.h>
+#include <inttypes.h>
+#include <limits.h>
+
+#include <vlib/vlib.h>
+#include <vlib/unix/unix.h>
+#include <vnet/plugin/plugin.h>
+#include <vnet/ethernet/ethernet.h>
+#include <vpp/app/version.h>
+
+#include <memif/memif.h>
+#include <memif/private.h>
+
+static u8 *
+memif_str2vec (uint8_t * str, int len)
+{
+  u8 *s = 0;
+  int i;
+
+  if (str[0] == 0)
+    return s;
+
+  for (i = 0; i < len; i++)
+    {
+      vec_add1 (s, str[i]);
+      if (str[i] == 0)
+	return s;
+    }
+  vec_add1 (s, 0);
+
+  return s;
+}
+
+static clib_error_t *
+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;
+
+  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)
+    return clib_error_return_unix (0, "sendmsg");
+  DBG ("Message type %u sent (fd %d)", msg->type, afd);
+  return 0;
+}
+
+static void
+memif_msg_enq_ack (memif_if_t * mif)
+{
+  memif_msg_fifo_elt_t *e;
+  clib_fifo_add2 (mif->msg_queue, e);
+
+  e->msg.type = MEMIF_MSG_TYPE_ACK;
+  e->fd = -1;
+}
+
+static clib_error_t *
+memif_msg_enq_hello (int fd)
+{
+  u8 *s;
+  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_m2s_ring = MEMIF_MAX_M2S_RING;
+  h->max_s2m_ring = MEMIF_MAX_M2S_RING;
+  h->max_region = MEMIF_MAX_REGION;
+  h->max_log2_ring_size = MEMIF_MAX_LOG2_RING_SIZE;
+  s = format (0, "VPP %s%c", VPP_BUILD_VER, 0);
+  strncpy ((char *) h->name, (char *) s, sizeof (h->name));
+  vec_free (s);
+  return memif_msg_send (fd, &msg, -1);
+}
+
+static void
+memif_msg_enq_init (memif_if_t * mif)
+{
+  u8 *s;
+  memif_msg_fifo_elt_t *e;
+  clib_fifo_add2 (mif->msg_queue, e);
+  memif_msg_init_t *i = &e->msg.init;
+
+  e->msg.type = MEMIF_MSG_TYPE_INIT;
+  e->fd = -1;
+  i->version = MEMIF_VERSION;
+  i->id = mif->id;
+  s = format (0, "VPP %s%c", VPP_BUILD_VER, 0);
+  strncpy ((char *) i->name, (char *) s, sizeof (i->name));
+  if (mif->secret)
+    strncpy ((char *) i->secret, (char *) mif->secret, sizeof (i->secret));
+  vec_free (s);
+}
+
+static void
+memif_msg_enq_add_region (memif_if_t * mif, u8 region)
+{
+  memif_msg_fifo_elt_t *e;
+  clib_fifo_add2 (mif->msg_queue, e);
+  memif_msg_add_region_t *ar = &e->msg.add_region;
+
+  e->msg.type = MEMIF_MSG_TYPE_ADD_REGION;
+  e->fd = mif->regions[region].fd;
+  ar->index = region;
+  ar->size = mif->regions[region].region_size;
+}
+
+static void
+memif_msg_enq_add_ring (memif_if_t * mif, u8 index, u8 direction)
+{
+  memif_msg_fifo_elt_t *e;
+  clib_fifo_add2 (mif->msg_queue, e);
+  memif_msg_add_ring_t *ar = &e->msg.add_ring;
+  memif_queue_t *mq;
+
+  ASSERT ((mif->flags & MEMIF_IF_FLAG_IS_SLAVE) != 0);
+
+  e->msg.type = MEMIF_MSG_TYPE_ADD_RING;
+
+  if (direction == MEMIF_RING_M2S)
+    mq = vec_elt_at_index (mif->rx_queues, index);
+  else
+    mq = vec_elt_at_index (mif->tx_queues, index);
+
+  e->fd = mq->int_fd;
+  ar->index = index;
+  ar->region = mq->region;
+  ar->offset = mq->offset;
+  ar->log2_ring_size = mq->log2_ring_size;
+  ar->flags = (direction == MEMIF_RING_S2M) ? MEMIF_MSG_ADD_RING_FLAG_S2M : 0;
+}
+
+static void
+memif_msg_enq_connect (memif_if_t * mif)
+{
+  memif_msg_fifo_elt_t *e;
+  clib_fifo_add2 (mif->msg_queue, e);
+  memif_msg_connect_t *c = &e->msg.connect;
+  u8 *s;
+
+  e->msg.type = MEMIF_MSG_TYPE_CONNECT;
+  e->fd = -1;
+  s = format (0, "%U%c", format_memif_device_name, mif->dev_instance, 0);
+  strncpy ((char *) c->if_name, (char *) s, sizeof (c->if_name));
+  vec_free (s);
+}
+
+static void
+memif_msg_enq_connected (memif_if_t * mif)
+{
+  memif_msg_fifo_elt_t *e;
+  clib_fifo_add2 (mif->msg_queue, e);
+  memif_msg_connected_t *c = &e->msg.connected;
+  u8 *s;
+
+  e->msg.type = MEMIF_MSG_TYPE_CONNECTED;
+  e->fd = -1;
+  s = format (0, "%U%c", format_memif_device_name, mif->dev_instance, 0);
+  strncpy ((char *) c->if_name, (char *) s, sizeof (c->if_name));
+  vec_free (s);
+}
+
+clib_error_t *
+memif_msg_send_disconnect (memif_if_t * mif, clib_error_t * err)
+{
+  memif_msg_t msg = { 0 };
+  msg.type = MEMIF_MSG_TYPE_DISCONNECT;
+  memif_msg_disconnect_t *d = &msg.disconnect;
+
+  d->code = err->code;
+  strncpy ((char *) d->string, (char *) err->what, sizeof (d->string));
+
+  return memif_msg_send (mif->conn_fd, &msg, -1);
+}
+
+static clib_error_t *
+memif_msg_receive_hello (memif_if_t * mif, memif_msg_t * msg)
+{
+  memif_msg_hello_t *h = &msg->hello;
+
+  if (msg->hello.min_version > MEMIF_VERSION ||
+      msg->hello.max_version < MEMIF_VERSION)
+    return clib_error_return (0, "incompatible protocol version");
+
+  mif->run.num_s2m_rings = clib_min (h->max_s2m_ring + 1,
+				     mif->cfg.num_s2m_rings);
+  mif->run.num_m2s_rings = clib_min (h->max_m2s_ring + 1,
+				     mif->cfg.num_m2s_rings);
+  mif->run.log2_ring_size = clib_min (h->max_log2_ring_size,
+				      mif->cfg.log2_ring_size);
+  mif->run.buffer_size = mif->cfg.buffer_size;
+
+  mif->remote_name = memif_str2vec (h->name, sizeof (h->name));
+
+  return 0;
+}
+
+static clib_error_t *
+memif_msg_receive_init (memif_if_t ** mifp, memif_msg_t * msg,
+			unix_file_t * uf)
+{
+  memif_main_t *mm = &memif_main;
+  memif_socket_file_t *msf =
+    vec_elt_at_index (mm->socket_files, uf->private_data);
+  memif_msg_init_t *i = &msg->init;
+  memif_if_t *mif, tmp;
+  clib_error_t *err;
+  uword *p;
+
+  if (i->version != MEMIF_VERSION)
+    {
+      memif_file_del_by_index (uf - unix_main.file_pool);
+      return clib_error_return (0, "unsupported version");
+    }
+
+  p = mhash_get (&msf->dev_instance_by_id, &i->id);
+
+  if (!p)
+    {
+      err = clib_error_return (0, "unmatched interface id");
+      goto error;
+    }
+
+  mif = vec_elt_at_index (mm->interfaces, p[0]);
+
+  if (mif->flags & MEMIF_IF_FLAG_IS_SLAVE)
+    {
+      err = clib_error_return (0, "cannot connect to slave");
+      goto error;
+    }
+
+  if (mif->conn_fd != -1)
+    {
+      err = clib_error_return (0, "already connected");
+      goto error;
+    }
+
+  if (i->mode != mif->mode)
+    {
+      err = clib_error_return (0, "mode mismatch");
+      goto error;
+    }
+
+  mif->conn_fd = uf->file_descriptor;
+  mif->conn_unix_file_index = uf - unix_main.file_pool;
+  hash_set (msf->dev_instance_by_fd, mif->conn_fd, mif->dev_instance);
+  mif->remote_name = memif_str2vec (i->name, sizeof (i->name));
+  *mifp = mif;
+
+  if (mif->secret)
+    {
+      u8 *s;
+      int r;
+      s = memif_str2vec (i->secret, sizeof (i->secret));
+      if (s == 0)
+	return clib_error_return (0, "secret required");
+
+      r = vec_cmp (s, mif->secret);
+      vec_free (s);
+
+      if (r)
+	return clib_error_return (0, "incorrect secret");
+    }
+
+  return 0;
+
+error:
+  tmp.conn_fd = uf->file_descriptor;
+  memif_msg_send_disconnect (&tmp, err);
+  memif_file_del_by_index (uf - unix_main.file_pool);
+  return err;
+}
+
+static clib_error_t *
+memif_msg_receive_add_region (memif_if_t * mif, memif_msg_t * msg, int fd)
+{
+  memif_msg_add_region_t *ar = &msg->add_region;
+  memif_region_t *mr;
+  if (fd < 0)
+    return clib_error_return (0, "missing memory region fd");
+
+  if (ar->index != vec_len (mif->regions))
+    return clib_error_return (0, "unexpected region index");
+
+  if (ar->index > MEMIF_MAX_REGION)
+    return clib_error_return (0, "too many regions");
+
+  vec_validate_aligned (mif->regions, ar->index, CLIB_CACHE_LINE_BYTES);
+  mr = vec_elt_at_index (mif->regions, ar->index);
+  mr->fd = fd;
+  mr->region_size = ar->size;
+
+  return 0;
+}
+
+static clib_error_t *
+memif_msg_receive_add_ring (memif_if_t * mif, memif_msg_t * msg, int fd)
+{
+  memif_msg_add_ring_t *ar = &msg->add_ring;
+  memif_queue_t *mq;
+
+  if (fd < 0)
+    return clib_error_return (0, "missing ring interrupt fd");
+
+  if (ar->flags & MEMIF_MSG_ADD_RING_FLAG_S2M)
+    {
+      if (ar->index != vec_len (mif->rx_queues))
+	return clib_error_return (0, "unexpected ring index");
+
+      if (ar->index > MEMIF_MAX_S2M_RING)
+	return clib_error_return (0, "too many rings");
+
+      vec_validate_aligned (mif->rx_queues, ar->index, CLIB_CACHE_LINE_BYTES);
+      mq = vec_elt_at_index (mif->rx_queues, ar->index);
+      mif->run.num_s2m_rings = vec_len (mif->rx_queues);
+    }
+  else
+    {
+      if (ar->index != vec_len (mif->tx_queues))
+	return clib_error_return (0, "unexpected ring index");
+
+      if (ar->index > MEMIF_MAX_M2S_RING)
+	return clib_error_return (0, "too many rings");
+
+      vec_validate_aligned (mif->tx_queues, ar->index, CLIB_CACHE_LINE_BYTES);
+      mq = vec_elt_at_index (mif->tx_queues, ar->index);
+      mif->run.num_m2s_rings = vec_len (mif->tx_queues);
+    }
+
+  mq->int_fd = fd;
+  mq->int_unix_file_index = ~0;
+  mq->log2_ring_size = ar->log2_ring_size;
+  mq->region = ar->region;
+  mq->offset = ar->offset;
+
+  return 0;
+}
+
+static clib_error_t *
+memif_msg_receive_connect (memif_if_t * mif, memif_msg_t * msg)
+{
+  clib_error_t *err;
+  memif_msg_connect_t *c = &msg->connect;
+
+  if ((err = memif_connect (mif)))
+    return err;
+
+  mif->remote_if_name = memif_str2vec (c->if_name, sizeof (c->if_name));
+
+  return 0;
+}
+
+static clib_error_t *
+memif_msg_receive_connected (memif_if_t * mif, memif_msg_t * msg)
+{
+  clib_error_t *err;
+  memif_msg_connected_t *c = &msg->connected;
+
+  if ((err = memif_connect (mif)))
+    return err;
+
+  mif->remote_if_name = memif_str2vec (c->if_name, sizeof (c->if_name));
+  return 0;
+}
+
+static clib_error_t *
+memif_msg_receive_disconnect (memif_if_t * mif, memif_msg_t * msg)
+{
+  memif_msg_disconnect_t *d = &msg->disconnect;
+
+  mif->remote_disc_string = memif_str2vec (d->string, sizeof (d->string));
+  return clib_error_return (0, "disconnect received");
+}
+
+static clib_error_t *
+memif_msg_receive (memif_if_t ** mifp, unix_file_t * uf)
+{
+  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;
+  clib_error_t *err = 0;
+  int fd = -1;
+  int i;
+  memif_if_t *mif = *mifp;
+
+  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);
+
+  /* receive the incoming message */
+  size = recvmsg (uf->file_descriptor, &mh, 0);
+  if (size != sizeof (memif_msg_t))
+    {
+      return (size == 0) ? clib_error_return (0, "disconnected") :
+	clib_error_return_unix (0,
+				"recvmsg: malformed message received on fd %d",
+				uf->file_descriptor);
+    }
+
+  if (mif == 0 && msg.type != MEMIF_MSG_TYPE_INIT)
+    {
+      memif_file_del (uf);
+      return clib_error_return (0, "unexpected message received");
+    }
+
+  /* process anciliary data */
+  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);
+  /* process the message based on its type */
+  switch (msg.type)
+    {
+    case MEMIF_MSG_TYPE_ACK:
+      break;
+
+    case MEMIF_MSG_TYPE_HELLO:
+      if ((err = memif_msg_receive_hello (mif, &msg)))
+	return err;
+      if ((err = memif_init_regions_and_queues (mif)))
+	return err;
+      memif_msg_enq_init (mif);
+      memif_msg_enq_add_region (mif, 0);
+      vec_foreach_index (i, mif->tx_queues)
+	memif_msg_enq_add_ring (mif, i, MEMIF_RING_S2M);
+      vec_foreach_index (i, mif->rx_queues)
+	memif_msg_enq_add_ring (mif, i, MEMIF_RING_M2S);
+      memif_msg_enq_connect (mif);
+      break;
+
+    case MEMIF_MSG_TYPE_INIT:
+      if ((err = memif_msg_receive_init (mifp, &msg, uf)))
+	return err;
+      mif = *mifp;
+      mif->remote_pid = cr->pid;
+      mif->remote_uid = cr->uid;
+      mif->remote_gid = cr->gid;
+      memif_msg_enq_ack (mif);
+      break;
+
+    case MEMIF_MSG_TYPE_ADD_REGION:
+      if ((err = memif_msg_receive_add_region (mif, &msg, fd)))
+	return err;
+      memif_msg_enq_ack (mif);
+      break;
+
+    case MEMIF_MSG_TYPE_ADD_RING:
+      if ((err = memif_msg_receive_add_ring (mif, &msg, fd)))
+	return err;
+      memif_msg_enq_ack (mif);
+      break;
+
+    case MEMIF_MSG_TYPE_CONNECT:
+      if ((err = memif_msg_receive_connect (mif, &msg)))
+	return err;
+      memif_msg_enq_connected (mif);
+      break;
+
+    case MEMIF_MSG_TYPE_CONNECTED:
+      if ((err = memif_msg_receive_connected (mif, &msg)))
+	return err;
+      break;
+
+    case MEMIF_MSG_TYPE_DISCONNECT:
+      if ((err = memif_msg_receive_disconnect (mif, &msg)))
+	return err;
+      break;
+
+    default:
+      err = clib_error_return (0, "unknown message type (0x%x)", msg.type);
+      return err;
+    }
+
+  if (clib_fifo_elts (mif->msg_queue) && mif->conn_unix_file_index != ~0)
+    unix_file_set_data_available_to_write (mif->conn_unix_file_index, 1);
+  return 0;
+}
+
+clib_error_t *
+memif_master_conn_fd_read_ready (unix_file_t * uf)
+{
+  memif_main_t *mm = &memif_main;
+  memif_socket_file_t *msf =
+    pool_elt_at_index (mm->socket_files, uf->private_data);
+  uword *p;
+  memif_if_t *mif = 0;
+  uword conn_unix_file_index = ~0;
+  clib_error_t *err = 0;
+
+  p = hash_get (msf->dev_instance_by_fd, uf->file_descriptor);
+  if (p)
+    {
+      mif = vec_elt_at_index (mm->interfaces, p[0]);
+    }
+  else
+    {
+      /* This is new connection, remove index from pending vector */
+      int i;
+      vec_foreach_index (i, msf->pending_file_indices)
+	if (msf->pending_file_indices[i] == uf - unix_main.file_pool)
+	{
+	  conn_unix_file_index = msf->pending_file_indices[i];
+	  vec_del1 (msf->pending_file_indices, i);
+	  break;
+	}
+      ASSERT (conn_unix_file_index != ~0);
+    }
+  err = memif_msg_receive (&mif, uf);
+  if (err)
+    {
+      memif_disconnect (mif, err);
+      clib_error_free (err);
+    }
+  return 0;
+}
+
+clib_error_t *
+memif_slave_conn_fd_read_ready (unix_file_t * uf)
+{
+  memif_main_t *mm = &memif_main;
+  clib_error_t *err;
+  memif_if_t *mif = vec_elt_at_index (mm->interfaces, uf->private_data);
+  err = memif_msg_receive (&mif, uf);
+  if (err)
+    {
+      memif_disconnect (mif, err);
+      clib_error_free (err);
+    }
+  return 0;
+}
+
+static clib_error_t *
+memif_conn_fd_write_ready (unix_file_t * uf, memif_if_t * mif)
+{
+  memif_msg_fifo_elt_t *e;
+  clib_fifo_sub2 (mif->msg_queue, e);
+  unix_file_set_data_available_to_write (mif->conn_unix_file_index, 0);
+  memif_msg_send (mif->conn_fd, &e->msg, e->fd);
+  return 0;
+}
+
+clib_error_t *
+memif_master_conn_fd_write_ready (unix_file_t * uf)
+{
+  memif_main_t *mm = &memif_main;
+  memif_socket_file_t *msf =
+    pool_elt_at_index (mm->socket_files, uf->private_data);
+  uword *p;
+  memif_if_t *mif;
+
+  p = hash_get (msf->dev_instance_by_fd, uf->file_descriptor);
+  if (!p)
+    return 0;
+
+  mif = vec_elt_at_index (mm->interfaces, p[0]);
+  return memif_conn_fd_write_ready (uf, mif);
+}
+
+clib_error_t *
+memif_slave_conn_fd_write_ready (unix_file_t * uf)
+{
+  memif_main_t *mm = &memif_main;
+  memif_if_t *mif = vec_elt_at_index (mm->interfaces, uf->private_data);
+  return memif_conn_fd_write_ready (uf, mif);
+}
+
+clib_error_t *
+memif_slave_conn_fd_error (unix_file_t * uf)
+{
+  memif_main_t *mm = &memif_main;
+  memif_if_t *mif = vec_elt_at_index (mm->interfaces, uf->private_data);
+  clib_error_t *err;
+
+  err = clib_error_return (0, "connection fd error");
+  memif_disconnect (mif, err);
+  clib_error_free (err);
+
+  return 0;
+}
+
+clib_error_t *
+memif_master_conn_fd_error (unix_file_t * uf)
+{
+  memif_main_t *mm = &memif_main;
+  memif_socket_file_t *msf =
+    pool_elt_at_index (mm->socket_files, uf->private_data);
+  uword *p;
+
+
+  p = hash_get (msf->dev_instance_by_fd, uf->file_descriptor);
+  if (p)
+    {
+      memif_if_t *mif;
+      clib_error_t *err;
+      mif = vec_elt_at_index (mm->interfaces, p[0]);
+      err = clib_error_return (0, "connection fd error");
+      memif_disconnect (mif, err);
+      clib_error_free (err);
+    }
+  else
+    {
+      int i;
+      vec_foreach_index (i, msf->pending_file_indices)
+	if (msf->pending_file_indices[i] == uf - unix_main.file_pool)
+	{
+	  vec_del1 (msf->pending_file_indices, i);
+	  memif_file_del (uf);
+	  return 0;
+	}
+    }
+
+  clib_warning ("Error on unknown file descriptor %d", uf->file_descriptor);
+  memif_file_del (uf);
+  return 0;
+}
+
+
+clib_error_t *
+memif_conn_fd_accept_ready (unix_file_t * uf)
+{
+  memif_main_t *mm = &memif_main;
+  memif_socket_file_t *msf =
+    pool_elt_at_index (mm->socket_files, uf->private_data);
+  int addr_len;
+  struct sockaddr_un client;
+  int conn_fd;
+  unix_file_t template = { 0 };
+  uword unix_file_index = ~0;
+  clib_error_t *err;
+
+
+  addr_len = sizeof (client);
+  conn_fd = accept (uf->file_descriptor,
+		    (struct sockaddr *) &client, (socklen_t *) & addr_len);
+
+  if (conn_fd < 0)
+    return clib_error_return_unix (0, "accept fd %d", uf->file_descriptor);
+
+  template.read_function = memif_master_conn_fd_read_ready;
+  template.write_function = memif_master_conn_fd_write_ready;
+  template.error_function = memif_master_conn_fd_error;
+  template.file_descriptor = conn_fd;
+  template.private_data = uf->private_data;
+
+  memif_file_add (&unix_file_index, &template);
+
+  err = memif_msg_enq_hello (conn_fd);
+  if (err)
+    {
+      clib_error_report (err);
+      memif_file_del_by_index (unix_file_index);
+    }
+  else
+    vec_add1 (msf->pending_file_indices, unix_file_index);
+
+  return 0;
+}
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */