Shared memory packet interface (memif) library

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

1 files changed, 883 insertions, 0 deletions

diff --git a/extras/libmemif/src/socket.c b/extras/libmemif/src/socket.c
new file mode 100644
index 00000000000..9c9b3a8dd73
--- /dev/null
+++ b/extras/libmemif/src/socket.c
@@ -0,0 +1,883 @@
+/*
+ *------------------------------------------------------------------
+ * Copyright (c) 2017 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *------------------------------------------------------------------
+ */
+
+#define _GNU_SOURCE
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <sys/un.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <net/if.h>
+#include <sys/ioctl.h>
+#include <sys/uio.h>
+#include <sys/mman.h>
+#include <sys/prctl.h>
+#include <fcntl.h>
+#include <errno.h>
+
+#include <socket.h>
+#include <memif.h>
+
+#define memif_min(a,b) ((a < b) ? (a) : (b))
+
+/* sends msg to socket */
+static_fn int
+memif_msg_send (int fd, memif_msg_t * msg, int afd)
+{
+  struct msghdr mh = { 0 };
+  struct iovec iov[1];
+  char ctl[CMSG_SPACE (sizeof (int))];
+  int rv, err = MEMIF_ERR_SUCCESS;	/* 0 */
+
+  iov[0].iov_base = (void *) msg;
+  iov[0].iov_len = sizeof (memif_msg_t);
+  mh.msg_iov = iov;
+  mh.msg_iovlen = 1;
+
+  if (afd > 0)
+    {
+      struct cmsghdr *cmsg;
+      memset (&ctl, 0, sizeof (ctl));
+      mh.msg_control = ctl;
+      mh.msg_controllen = sizeof (ctl);
+      cmsg = CMSG_FIRSTHDR (&mh);
+      cmsg->cmsg_len = CMSG_LEN (sizeof (int));
+      cmsg->cmsg_level = SOL_SOCKET;
+      cmsg->cmsg_type = SCM_RIGHTS;
+      memcpy (CMSG_DATA (cmsg), &afd, sizeof (int));
+    }
+  rv = sendmsg (fd, &mh, 0);
+  if (rv < 0)
+    err = memif_syscall_error_handler (errno);
+  DBG ("Message type %u sent", msg->type);
+  return err;
+}
+
+/* response from memif master - master is ready to handle next message */
+static_fn int
+memif_msg_enq_ack (memif_connection_t * c)
+{
+  memif_msg_queue_elt_t *e =
+    (memif_msg_queue_elt_t *) malloc (sizeof (memif_msg_queue_elt_t));
+  if (e == NULL)
+    return memif_syscall_error_handler (errno);
+
+  memset (&e->msg, 0, sizeof (e->msg));
+  e->msg.type = MEMIF_MSG_TYPE_ACK;
+  e->fd = -1;
+
+  e->next = NULL;
+  if (c->msg_queue == NULL)
+    {
+      c->msg_queue = e;
+      return MEMIF_ERR_SUCCESS;	/* 0 */
+    }
+
+  memif_msg_queue_elt_t *cur = c->msg_queue;
+  while (cur->next != NULL)
+    {
+      cur = cur->next;
+    }
+  cur->next = e;
+
+  return MEMIF_ERR_SUCCESS;	/* 0 */
+}
+
+static_fn int
+memif_msg_send_hello (int fd)
+{
+  libmemif_main_t *lm = &libmemif_main;
+  memif_msg_t msg = { 0 };
+  memif_msg_hello_t *h = &msg.hello;
+  msg.type = MEMIF_MSG_TYPE_HELLO;
+  h->min_version = MEMIF_VERSION;
+  h->max_version = MEMIF_VERSION;
+  h->max_s2m_ring = MEMIF_MAX_M2S_RING;
+  h->max_m2s_ring = MEMIF_MAX_M2S_RING;
+  h->max_region = MEMIF_MAX_REGION;
+  h->max_log2_ring_size = MEMIF_MAX_LOG2_RING_SIZE;
+
+  strncpy ((char *) h->name, lm->app_name, strlen (lm->app_name));
+
+  /* msg hello is not enqueued but sent directly,
+     because it is the first msg to be sent */
+  return memif_msg_send (fd, &msg, -1);
+}
+
+/* send id and secret (optional) for interface identification */
+static_fn int
+memif_msg_enq_init (memif_connection_t * c)
+{
+  memif_msg_queue_elt_t *e =
+    (memif_msg_queue_elt_t *) malloc (sizeof (memif_msg_queue_elt_t));
+  if (e == NULL)
+    return memif_syscall_error_handler (errno);
+  memset (e, 0, sizeof (memif_msg_queue_elt_t));
+
+  memset (&e->msg, 0, sizeof (e->msg));
+  memif_msg_init_t *i = &e->msg.init;
+
+  e->msg.type = MEMIF_MSG_TYPE_INIT;
+  e->fd = -1;
+  i->version = MEMIF_VERSION;
+  i->id = c->args.interface_id;
+  i->mode = c->args.mode;
+
+  strncpy ((char *) i->name, (char *) c->args.instance_name,
+	   strlen ((char *) c->args.instance_name));
+  if (c->args.secret)
+    strncpy ((char *) i->secret, (char *) c->args.secret, sizeof (i->secret));
+
+  e->next = NULL;
+  if (c->msg_queue == NULL)
+    {
+      c->msg_queue = e;
+      return MEMIF_ERR_SUCCESS;	/* 0 */
+    }
+
+  memif_msg_queue_elt_t *cur = c->msg_queue;
+  while (cur->next != NULL)
+    {
+      cur = cur->next;
+    }
+  cur->next = e;
+
+  return MEMIF_ERR_SUCCESS;	/* 0 */
+}
+
+/* send information about region specified by region_index */
+static_fn int
+memif_msg_enq_add_region (memif_connection_t * c, uint8_t region_index)
+{
+  /* maybe check if region is valid? */
+  memif_region_t *mr = &c->regions[region_index];
+
+  memif_msg_queue_elt_t *e =
+    (memif_msg_queue_elt_t *) malloc (sizeof (memif_msg_queue_elt_t));
+  if (e == NULL)
+    return memif_syscall_error_handler (errno);
+
+  memset (&e->msg, 0, sizeof (e->msg));
+  memif_msg_add_region_t *ar = &e->msg.add_region;
+
+  e->msg.type = MEMIF_MSG_TYPE_ADD_REGION;
+  e->fd = mr->fd;
+  ar->index = region_index;
+  ar->size = mr->region_size;
+
+  e->next = NULL;
+  if (c->msg_queue == NULL)
+    {
+      c->msg_queue = e;
+      return MEMIF_ERR_SUCCESS;	/* 0 */
+    }
+
+  memif_msg_queue_elt_t *cur = c->msg_queue;
+  while (cur->next != NULL)
+    {
+      cur = cur->next;
+    }
+  cur->next = e;
+
+  return MEMIF_ERR_SUCCESS;	/* 0 */
+}
+
+/* send information about ring specified by direction (S2M | M2S) and index */
+static_fn int
+memif_msg_enq_add_ring (memif_connection_t * c, uint8_t index, uint8_t dir)
+{
+  memif_msg_queue_elt_t *e =
+    (memif_msg_queue_elt_t *) malloc (sizeof (memif_msg_queue_elt_t));
+  if (e == NULL)
+    return memif_syscall_error_handler (errno);
+
+  memset (&e->msg, 0, sizeof (e->msg));
+  memif_msg_add_ring_t *ar = &e->msg.add_ring;
+
+  e->msg.type = MEMIF_MSG_TYPE_ADD_RING;
+
+  /* TODO: support multiple rings */
+  memif_queue_t *mq;
+  if (dir == MEMIF_RING_M2S)
+    mq = &c->rx_queues[index];
+  else
+    mq = &c->tx_queues[index];
+
+  e->fd = mq->int_fd;
+  ar->index = index;
+  ar->offset = mq->offset;
+  ar->region = mq->region;
+  ar->log2_ring_size = mq->log2_ring_size;
+  ar->flags = (dir == MEMIF_RING_S2M) ? MEMIF_MSG_ADD_RING_FLAG_S2M : 0;
+
+  e->next = NULL;
+  if (c->msg_queue == NULL)
+    {
+      c->msg_queue = e;
+      return MEMIF_ERR_SUCCESS;	/* 0 */
+    }
+
+  memif_msg_queue_elt_t *cur = c->msg_queue;
+  while (cur->next != NULL)
+    {
+      cur = cur->next;
+    }
+  cur->next = e;
+
+  return MEMIF_ERR_SUCCESS;	/* 0 */
+}
+
+/* used as connection request from slave */
+static_fn int
+memif_msg_enq_connect (memif_connection_t * c)
+{
+  memif_msg_queue_elt_t *e =
+    (memif_msg_queue_elt_t *) malloc (sizeof (memif_msg_queue_elt_t));
+  if (e == NULL)
+    return memif_syscall_error_handler (errno);
+
+  memset (&e->msg, 0, sizeof (e->msg));
+  memif_msg_connect_t *cm = &e->msg.connect;
+
+  e->msg.type = MEMIF_MSG_TYPE_CONNECT;
+  e->fd = -1;
+  strncpy ((char *) cm->if_name, (char *) c->args.interface_name,
+	   strlen ((char *) c->args.interface_name));
+
+  e->next = NULL;
+  if (c->msg_queue == NULL)
+    {
+      c->msg_queue = e;
+      return MEMIF_ERR_SUCCESS;	/* 0 */
+    }
+
+  memif_msg_queue_elt_t *cur = c->msg_queue;
+  while (cur->next != NULL)
+    {
+      cur = cur->next;
+    }
+  cur->next = e;
+
+  return MEMIF_ERR_SUCCESS;	/* 0 */
+}
+
+/* used as confirmation of connection by master */
+static_fn int
+memif_msg_enq_connected (memif_connection_t * c)
+{
+  memif_msg_queue_elt_t *e =
+    (memif_msg_queue_elt_t *) malloc (sizeof (memif_msg_queue_elt_t));
+  if (e == NULL)
+    return memif_syscall_error_handler (errno);
+
+  memset (&e->msg, 0, sizeof (e->msg));
+  memif_msg_connected_t *cm = &e->msg.connected;
+
+  e->msg.type = MEMIF_MSG_TYPE_CONNECTED;
+  e->fd = -1;
+  strncpy ((char *) cm->if_name, (char *) c->args.interface_name,
+	   strlen ((char *) c->args.interface_name));
+
+  e->next = NULL;
+  if (c->msg_queue == NULL)
+    {
+      c->msg_queue = e;
+      return MEMIF_ERR_SUCCESS;	/* 0 */
+    }
+
+  memif_msg_queue_elt_t *cur = c->msg_queue;
+  while (cur->next != NULL)
+    {
+      cur = cur->next;
+    }
+  cur->next = e;
+
+  return MEMIF_ERR_SUCCESS;	/* 0 */
+}
+
+/* immediately send disconnect msg */
+    /* specifie protocol for disconnect msg err_code
+       so that it will be compatible with VPP? (header/doc) */
+int
+memif_msg_send_disconnect (int fd, uint8_t * err_string, uint32_t err_code)
+{
+  memif_msg_t msg = { 0 };
+  memif_msg_disconnect_t *d = &msg.disconnect;
+
+  msg.type = MEMIF_MSG_TYPE_DISCONNECT;
+  d->code = err_code;
+  uint16_t l = strlen ((char *) err_string);
+  if (l > 96)
+    {
+      DBG ("Disconnect string too long. Sending first 96 characters.");
+      l = 96;
+    }
+  strncpy ((char *) d->string, (char *) err_string, l);
+
+  return memif_msg_send (fd, &msg, -1);
+}
+
+static_fn int
+memif_msg_receive_hello (memif_connection_t * c, memif_msg_t * msg)
+{
+  memif_msg_hello_t *h = &msg->hello;
+
+  if (msg->hello.min_version > MEMIF_VERSION ||
+      msg->hello.max_version < MEMIF_VERSION)
+    {
+      DBG ("incompatible protocol version");
+      return MEMIF_ERR_PROTO;
+    }
+
+  c->run_args.num_s2m_rings = memif_min (h->max_s2m_ring + 1,
+					 c->args.num_s2m_rings);
+  c->run_args.num_m2s_rings = memif_min (h->max_m2s_ring + 1,
+					 c->args.num_m2s_rings);
+  c->run_args.log2_ring_size = memif_min (h->max_log2_ring_size,
+					  c->args.log2_ring_size);
+  c->run_args.buffer_size = c->args.buffer_size;
+  strncpy ((char *) c->remote_name, (char *) h->name,
+	   strlen ((char *) h->name));
+
+  return MEMIF_ERR_SUCCESS;	/* 0 */
+}
+
+/* handle interface identification (id, secret (optional)) */
+static_fn int
+memif_msg_receive_init (memif_socket_t * ms, int fd, memif_msg_t * msg)
+{
+  memif_msg_init_t *i = &msg->init;
+  memif_list_elt_t *elt = NULL;
+  memif_list_elt_t elt2;
+  memif_connection_t *c = NULL;
+  libmemif_main_t *lm = &libmemif_main;
+  uint8_t err_string[96];
+  memset (err_string, 0, sizeof (char) * 96);
+  int err = MEMIF_ERR_SUCCESS;	/* 0 */
+  int err_disc;
+  if (i->version != MEMIF_VERSION)
+    {
+      DBG ("MEMIF_VER_ERR");
+      strncpy ((char *) err_string, MEMIF_VER_ERR, strlen (MEMIF_VER_ERR));
+      err = MEMIF_ERR_PROTO;
+      goto error;
+    }
+
+  get_list_elt (&elt, ms->interface_list, ms->interface_list_len, i->id);
+  if (elt == NULL)
+    {
+      DBG ("MEMIF_ID_ERR");
+      strncpy ((char *) err_string, MEMIF_ID_ERR, strlen (MEMIF_ID_ERR));
+      err = MEMIF_ERR_ID;
+      goto error;
+    }
+
+  c = (memif_connection_t *) elt->data_struct;
+
+  if (!(c->args.is_master))
+    {
+      DBG ("MEMIF_SLAVE_ERR");
+      strncpy ((char *) err_string, MEMIF_SLAVE_ERR,
+	       strlen (MEMIF_SLAVE_ERR));
+      err = MEMIF_ERR_ACCSLAVE;
+      goto error;
+    }
+  if (c->fd != -1)
+    {
+      DBG ("MEMIF_CONN_ERR");
+      strncpy ((char *) err_string, MEMIF_CONN_ERR, strlen (MEMIF_CONN_ERR));
+      err = MEMIF_ERR_ALRCONN;
+      goto error;
+    }
+
+  c->fd = fd;
+
+  if (i->mode != c->args.mode)
+    {
+      DBG ("MEMIF_MODE_ERR");
+      strncpy ((char *) err_string, MEMIF_MODE_ERR, strlen (MEMIF_MODE_ERR));
+      err = MEMIF_ERR_MODE;
+      goto error;
+    }
+
+  strncpy ((char *) c->remote_name, (char *) i->name,
+	   strlen ((char *) i->name));
+
+  if (c->args.secret)
+    {
+      int r;
+      if (i->secret)
+	{
+	  if (strlen ((char *) c->args.secret) != strlen ((char *) i->secret))
+	    {
+	      DBG ("MEMIF_SECRET_ERR");
+	      strncpy ((char *) err_string,
+		       MEMIF_SECRET_ERR, strlen (MEMIF_SECRET_ERR));
+	      err = MEMIF_ERR_SECRET;
+	      goto error;
+	    }
+	  r = strncmp ((char *) i->secret, (char *) c->args.secret,
+		       strlen ((char *) c->args.secret));
+	  if (r != 0)
+	    {
+	      DBG ("MEMIF_SECRET_ERR");
+	      strncpy ((char *) err_string,
+		       MEMIF_SECRET_ERR, strlen (MEMIF_SECRET_ERR));
+	      err = MEMIF_ERR_SECRET;
+	      goto error;
+	    }
+	}
+      else
+	{
+	  DBG ("MEMIF_NOSECRET_ERR");
+	  strncpy ((char *) err_string,
+		   MEMIF_NOSECRET_ERR, strlen (MEMIF_NOSECRET_ERR));
+	  err = MEMIF_ERR_NOSECRET;
+	  goto error;
+	}
+    }
+
+  c->read_fn = memif_conn_fd_read_ready;
+  c->write_fn = memif_conn_fd_write_ready;
+  c->error_fn = memif_conn_fd_error;
+
+  elt2.key = c->fd;
+  elt2.data_struct = c;
+
+  add_list_elt (&elt2, &lm->control_list, &lm->control_list_len);
+  free_list_elt (lm->pending_list, lm->pending_list_len, fd);
+
+  return err;
+
+error:
+  memif_msg_send_disconnect (fd, err_string, 0);
+  lm->control_fd_update (fd, MEMIF_FD_EVENT_DEL);
+  free_list_elt (lm->pending_list, lm->pending_list_len, fd);
+  close (fd);
+  fd = -1;
+  return err;
+}
+
+/* receive region information and add new region to connection (if possible) */
+static_fn int
+memif_msg_receive_add_region (memif_connection_t * c, memif_msg_t * msg,
+			      int fd)
+{
+  memif_msg_add_region_t *ar = &msg->add_region;
+  memif_region_t *mr;
+  if (fd < 0)
+    return MEMIF_ERR_NO_SHMFD;
+
+  if (ar->index > MEMIF_MAX_REGION)
+    return MEMIF_ERR_MAXREG;
+
+  mr =
+    (memif_region_t *) realloc (c->regions,
+				sizeof (memif_region_t) * (ar->index + 1));
+  if (mr == NULL)
+    return memif_syscall_error_handler (errno);
+  c->regions = mr;
+  c->regions[ar->index].fd = fd;
+  c->regions[ar->index].region_size = ar->size;
+  c->regions[ar->index].shm = NULL;
+
+  return MEMIF_ERR_SUCCESS;	/* 0 */
+}
+
+/* receive ring information and add new ring to connection queue
+   (based on direction S2M | M2S) */
+static_fn int
+memif_msg_receive_add_ring (memif_connection_t * c, memif_msg_t * msg, int fd)
+{
+  memif_msg_add_ring_t *ar = &msg->add_ring;
+
+  memif_queue_t *mq;
+
+  if (fd < 0)
+    return MEMIF_ERR_NO_INTFD;
+
+  if (ar->flags & MEMIF_MSG_ADD_RING_FLAG_S2M)
+    {
+      if (ar->index > MEMIF_MAX_S2M_RING)
+	return MEMIF_ERR_MAXRING;
+      if (ar->index >= c->args.num_s2m_rings)
+	return MEMIF_ERR_MAXRING;
+
+      mq =
+	(memif_queue_t *) realloc (c->rx_queues,
+				   sizeof (memif_queue_t) * (ar->index + 1));
+      if (mq == NULL)
+	return memif_syscall_error_handler (errno);
+      c->rx_queues = mq;
+      c->rx_queues[ar->index].int_fd = fd;
+      c->rx_queues[ar->index].log2_ring_size = ar->log2_ring_size;
+      c->rx_queues[ar->index].region = ar->region;
+      c->rx_queues[ar->index].offset = ar->offset;
+      c->run_args.num_s2m_rings++;
+    }
+  else
+    {
+      if (ar->index > MEMIF_MAX_M2S_RING)
+	return MEMIF_ERR_MAXRING;
+      if (ar->index >= c->args.num_m2s_rings)
+	return MEMIF_ERR_MAXRING;
+
+      mq =
+	(memif_queue_t *) realloc (c->tx_queues,
+				   sizeof (memif_queue_t) * (ar->index + 1));
+      if (mq == NULL)
+	return memif_syscall_error_handler (errno);
+      c->tx_queues = mq;
+      c->tx_queues[ar->index].int_fd = fd;
+      c->tx_queues[ar->index].log2_ring_size = ar->log2_ring_size;
+      c->tx_queues[ar->index].region = ar->region;
+      c->tx_queues[ar->index].offset = ar->offset;
+      c->run_args.num_m2s_rings++;
+    }
+
+  return MEMIF_ERR_SUCCESS;	/* 0 */
+}
+
+/* slave -> master */
+static_fn int
+memif_msg_receive_connect (memif_connection_t * c, memif_msg_t * msg)
+{
+  memif_msg_connect_t *cm = &msg->connect;
+  libmemif_main_t *lm = &libmemif_main;
+  memif_list_elt_t elt;
+
+  int err;
+  err = memif_connect1 (c);
+  if (err != MEMIF_ERR_SUCCESS)
+    return err;
+
+  strncpy ((char *) c->remote_if_name, (char *) cm->if_name,
+	   strlen ((char *) cm->if_name));
+
+  int i;
+  if (c->on_interrupt != NULL)
+    {
+      for (i = 0; i < c->run_args.num_m2s_rings; i++)
+	{
+	  elt.key = c->rx_queues[i].int_fd;
+	  elt.data_struct = c;
+	  add_list_elt (&elt, &lm->interrupt_list, &lm->interrupt_list_len);
+
+	  lm->control_fd_update (c->rx_queues[i].int_fd, MEMIF_FD_EVENT_READ);
+	}
+
+    }
+
+  c->on_connect ((void *) c, c->private_ctx);
+
+  return err;
+}
+
+/* master -> slave */
+static_fn int
+memif_msg_receive_connected (memif_connection_t * c, memif_msg_t * msg)
+{
+  memif_msg_connect_t *cm = &msg->connect;
+  libmemif_main_t *lm = &libmemif_main;
+
+  int err;
+  err = memif_connect1 (c);
+  if (err != MEMIF_ERR_SUCCESS)
+    return err;
+
+  strncpy ((char *) c->remote_if_name, (char *) cm->if_name,
+	   strlen ((char *) cm->if_name));
+
+  int i;
+  if (c->on_interrupt != NULL)
+    {
+      for (i = 0; i < c->run_args.num_s2m_rings; i++)
+	lm->control_fd_update (c->rx_queues[i].int_fd, MEMIF_FD_EVENT_READ);
+    }
+
+  c->on_connect ((void *) c, c->private_ctx);
+
+  return err;
+}
+
+static_fn int
+memif_msg_receive_disconnect (memif_connection_t * c, memif_msg_t * msg)
+{
+  memif_msg_disconnect_t *d = &msg->disconnect;
+
+  memset (c->remote_disconnect_string, 0,
+	  sizeof (c->remote_disconnect_string));
+  strncpy ((char *) c->remote_disconnect_string, (char *) d->string,
+	   strlen ((char *) d->string));
+
+  /* on returning error, handle function will call memif_disconnect () */
+  DBG ("disconnect received: %s, mode: %d",
+       c->remote_disconnect_string, c->args.mode);
+  return MEMIF_ERR_DISCONNECT;
+}
+
+static_fn int
+memif_msg_receive (int ifd)
+{
+  char ctl[CMSG_SPACE (sizeof (int)) +
+	   CMSG_SPACE (sizeof (struct ucred))] = { 0 };
+  struct msghdr mh = { 0 };
+  struct iovec iov[1];
+  memif_msg_t msg = { 0 };
+  ssize_t size;
+  int err = MEMIF_ERR_SUCCESS;	/* 0 */
+  int fd = -1;
+  int i;
+  libmemif_main_t *lm = &libmemif_main;
+  memif_connection_t *c = NULL;
+  memif_socket_t *ms = NULL;
+  memif_list_elt_t *elt = NULL;
+
+  iov[0].iov_base = (void *) &msg;
+  iov[0].iov_len = sizeof (memif_msg_t);
+  mh.msg_iov = iov;
+  mh.msg_iovlen = 1;
+  mh.msg_control = ctl;
+  mh.msg_controllen = sizeof (ctl);
+
+  DBG ("recvmsg fd %d", ifd);
+  size = recvmsg (ifd, &mh, 0);
+  DBG ("done");
+  if (size != sizeof (memif_msg_t))
+    {
+      if (size == 0)
+	return MEMIF_ERR_DISCONNECTED;
+      else
+	return MEMIF_ERR_MFMSG;
+    }
+
+  struct ucred *cr = 0;
+  struct cmsghdr *cmsg;
+
+  cmsg = CMSG_FIRSTHDR (&mh);
+  while (cmsg)
+    {
+      if (cmsg->cmsg_level == SOL_SOCKET)
+	{
+	  if (cmsg->cmsg_type == SCM_CREDENTIALS)
+	    {
+	      cr = (struct ucred *) CMSG_DATA (cmsg);
+	    }
+	  else if (cmsg->cmsg_type == SCM_RIGHTS)
+	    {
+	      int *fdp = (int *) CMSG_DATA (cmsg);
+	      fd = *fdp;
+	    }
+	}
+      cmsg = CMSG_NXTHDR (&mh, cmsg);
+    }
+
+  DBG ("Message type %u received", msg.type);
+
+  get_list_elt (&elt, lm->control_list, lm->control_list_len, ifd);
+  if (elt != NULL)
+    c = (memif_connection_t *) elt->data_struct;
+
+  switch (msg.type)
+    {
+    case MEMIF_MSG_TYPE_ACK:
+      break;
+
+    case MEMIF_MSG_TYPE_HELLO:
+      if ((err = memif_msg_receive_hello (c, &msg)) != MEMIF_ERR_SUCCESS)
+	return err;
+      if ((err = memif_init_regions_and_queues (c)) != MEMIF_ERR_SUCCESS)
+	return err;
+      if ((err = memif_msg_enq_init (c)) != MEMIF_ERR_SUCCESS)
+	return err;
+      if ((err = memif_msg_enq_add_region (c, 0)) != MEMIF_ERR_SUCCESS)
+	return err;
+      for (i = 0; i < c->run_args.num_s2m_rings; i++)
+	{
+	  if ((err =
+	       memif_msg_enq_add_ring (c, i,
+				       MEMIF_RING_S2M)) != MEMIF_ERR_SUCCESS)
+	    return err;
+	}
+      for (i = 0; i < c->run_args.num_m2s_rings; i++)
+	{
+	  if ((err =
+	       memif_msg_enq_add_ring (c, i,
+				       MEMIF_RING_M2S)) != MEMIF_ERR_SUCCESS)
+	    return err;
+	}
+      if ((err = memif_msg_enq_connect (c)) != MEMIF_ERR_SUCCESS)
+	return err;
+      break;
+
+    case MEMIF_MSG_TYPE_INIT:
+      get_list_elt (&elt, lm->pending_list, lm->pending_list_len, ifd);
+      if (elt == NULL)
+	return -1;
+      ms = (memif_socket_t *) elt->data_struct;
+      if ((err = memif_msg_receive_init (ms, ifd, &msg)) != MEMIF_ERR_SUCCESS)
+	return err;
+      /* c->remote_pid = cr->pid */
+      /* c->remote_uid = cr->uid */
+      /* c->remote_gid = cr->gid */
+      get_list_elt (&elt, lm->control_list, lm->control_list_len, ifd);
+      if (elt == NULL)
+	return -1;
+      c = (memif_connection_t *) elt->data_struct;
+      if ((err = memif_msg_enq_ack (c)) != MEMIF_ERR_SUCCESS)
+	return err;
+      break;
+
+    case MEMIF_MSG_TYPE_ADD_REGION:
+      if ((err =
+	   memif_msg_receive_add_region (c, &msg, fd)) != MEMIF_ERR_SUCCESS)
+	return err;
+      if ((err = memif_msg_enq_ack (c)) != MEMIF_ERR_SUCCESS)
+	return err;
+      break;
+
+    case MEMIF_MSG_TYPE_ADD_RING:
+      if ((err =
+	   memif_msg_receive_add_ring (c, &msg, fd)) != MEMIF_ERR_SUCCESS)
+	return err;
+      if ((err = memif_msg_enq_ack (c)) != MEMIF_ERR_SUCCESS)
+	return err;
+      break;
+
+    case MEMIF_MSG_TYPE_CONNECT:
+      if ((err = memif_msg_receive_connect (c, &msg)) != MEMIF_ERR_SUCCESS)
+	return err;
+      if ((err = memif_msg_enq_connected (c)) != MEMIF_ERR_SUCCESS)
+	return err;
+      break;
+
+    case MEMIF_MSG_TYPE_CONNECTED:
+      if ((err = memif_msg_receive_connected (c, &msg)) != MEMIF_ERR_SUCCESS)
+	return err;
+      break;
+
+    case MEMIF_MSG_TYPE_DISCONNECT:
+      if ((err = memif_msg_receive_disconnect (c, &msg)) != MEMIF_ERR_SUCCESS)
+	return err;
+      break;
+
+    default:
+      return MEMIF_ERR_UNKNOWN_MSG;;
+      break;
+    }
+
+  if (c != NULL)
+    c->flags |= MEMIF_CONNECTION_FLAG_WRITE;
+/*    libmemif_main_t *lm = &libmemif_main;
+    lm->control_fd_update (c->fd, MEMIF_FD_EVENT_READ | MEMIF_FD_EVENT_MOD); */
+  return MEMIF_ERR_SUCCESS;	/* 0 */
+}
+
+int
+memif_conn_fd_error (memif_connection_t * c)
+{
+  DBG ("connection fd error");
+  strncpy ((char *) c->remote_disconnect_string, "connection fd error", 19);
+  int err = memif_disconnect_internal (c);
+  return err;
+}
+
+/* calls memif_msg_receive to handle pending messages on socket */
+int
+memif_conn_fd_read_ready (memif_connection_t * c)
+{
+  int err;
+  err = memif_msg_receive (c->fd);
+  if (err != 0)
+    {
+      err = memif_disconnect_internal (c);
+    }
+  return err;
+}
+
+/* get msg from msg queue buffer and send it to socket */
+int
+memif_conn_fd_write_ready (memif_connection_t * c)
+{
+  int err = MEMIF_ERR_SUCCESS;	/* 0 */
+
+
+  if ((c->flags & MEMIF_CONNECTION_FLAG_WRITE) == 0)
+    goto done;
+
+  memif_msg_queue_elt_t *e = c->msg_queue;
+  if (e == NULL)
+    goto done;
+
+  c->msg_queue = c->msg_queue->next;
+
+  c->flags &= ~MEMIF_CONNECTION_FLAG_WRITE;
+/*
+    libmemif_main_t *lm = &libmemif_main;
+
+    lm->control_fd_update (c->fd,
+        MEMIF_FD_EVENT_READ | MEMIF_FD_EVENT_WRITE | MEMIF_FD_EVENT_MOD);
+*/
+  err = memif_msg_send (c->fd, &e->msg, e->fd);
+  free (e);
+  goto done;
+
+done:
+  return err;
+}
+
+int
+memif_conn_fd_accept_ready (memif_socket_t * ms)
+{
+  int addr_len;
+  struct sockaddr_un client;
+  int conn_fd;
+  libmemif_main_t *lm = &libmemif_main;
+
+  DBG ("accept called");
+
+  addr_len = sizeof (client);
+  conn_fd =
+    accept (ms->fd, (struct sockaddr *) &client, (socklen_t *) & addr_len);
+
+  if (conn_fd < 0)
+    {
+      return memif_syscall_error_handler (errno);
+    }
+  DBG ("accept fd %d", ms->fd);
+  DBG ("conn fd %d", conn_fd);
+
+  memif_list_elt_t elt;
+  elt.key = conn_fd;
+  elt.data_struct = ms;
+
+  add_list_elt (&elt, &lm->pending_list, &lm->pending_list_len);
+  lm->control_fd_update (conn_fd, MEMIF_FD_EVENT_READ | MEMIF_FD_EVENT_WRITE);
+
+  return memif_msg_send_hello (conn_fd);
+}
+
+int
+memif_read_ready (int fd)
+{
+  int err;
+  DBG ("call recv");
+  err = memif_msg_receive (fd);
+  DBG ("recv finished");
+  return err;
+}