/****************************************************************************
 * net/usrsock/usrsock_accept.c
 *
 *   Copyright (C) 2018 Pinecone Inc. All rights reserved.
 *   Author: Xiang Xiao <xiaoxiang@pinecone.net>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name NuttX nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <nuttx/config.h>
#if defined(CONFIG_NET) && defined(CONFIG_NET_USRSOCK)

#include <assert.h>
#include <errno.h>
#include <debug.h>

#include <nuttx/semaphore.h>
#include <nuttx/net/net.h>
#include <nuttx/net/usrsock.h>

#include "usrsock/usrsock.h"

/****************************************************************************
 * Private Functions
 ****************************************************************************/

static uint16_t accept_event(FAR struct net_driver_s *dev, FAR void *pvconn,
                             FAR void *pvpriv, uint16_t flags)
{
  FAR struct usrsock_data_reqstate_s *pstate = pvpriv;
  FAR struct usrsock_conn_s *conn = pvconn;

  if (flags & USRSOCK_EVENT_ABORT)
    {
      ninfo("socket aborted.\n");

      pstate->reqstate.result = -ECONNABORTED;
      pstate->valuelen = 0;
      pstate->valuelen_nontrunc = 0;

      /* Stop further callbacks */

      pstate->reqstate.cb->flags   = 0;
      pstate->reqstate.cb->priv    = NULL;
      pstate->reqstate.cb->event   = NULL;

      /* Wake up the waiting thread */

      nxsem_post(&pstate->reqstate.recvsem);
    }
  else if (flags & USRSOCK_EVENT_REQ_COMPLETE)
    {
      ninfo("request completed.\n");

      pstate->reqstate.result = conn->resp.result;
      if (pstate->reqstate.result < 0)
        {
          pstate->valuelen = 0;
          pstate->valuelen_nontrunc = 0;
        }
      else
        {
          pstate->valuelen = conn->resp.valuelen;
          pstate->valuelen_nontrunc = conn->resp.valuelen_nontrunc;
        }

      if (pstate->reqstate.result >= 0 ||
          pstate->reqstate.result == -EAGAIN)
        {
          /* After reception of connection, mark input not ready. Daemon will
           * send event to restore this flag. */

          conn->flags &= ~USRSOCK_EVENT_RECVFROM_AVAIL;
        }

      /* Stop further callbacks */

      pstate->reqstate.cb->flags   = 0;
      pstate->reqstate.cb->priv    = NULL;
      pstate->reqstate.cb->event   = NULL;

      /* Wake up the waiting thread */

      nxsem_post(&pstate->reqstate.recvsem);
    }
  else if (flags & USRSOCK_EVENT_REMOTE_CLOSED)
    {
      ninfo("remote closed.\n");

      pstate->reqstate.result = -EPIPE;

      /* Stop further callbacks */

      pstate->reqstate.cb->flags   = 0;
      pstate->reqstate.cb->priv    = NULL;
      pstate->reqstate.cb->event   = NULL;

      /* Wake up the waiting thread */

      nxsem_post(&pstate->reqstate.recvsem);
    }
  else if (flags & USRSOCK_EVENT_RECVFROM_AVAIL)
    {
      ninfo("accept avail.\n");

      flags &= ~USRSOCK_EVENT_RECVFROM_AVAIL;

      /* Stop further callbacks */

      pstate->reqstate.cb->flags   = 0;
      pstate->reqstate.cb->priv    = NULL;
      pstate->reqstate.cb->event   = NULL;

      /* Wake up the waiting thread */

      nxsem_post(&pstate->reqstate.recvsem);
    }

  return flags;
}

/****************************************************************************
 * Name: do_accept_request
 ****************************************************************************/

static int do_accept_request(FAR struct usrsock_conn_s *conn, socklen_t addrlen)
{
  struct usrsock_request_accept_s req = {};
  struct iovec bufs[1];

  if (addrlen > UINT16_MAX)
    {
      addrlen = UINT16_MAX;
    }

  /* Prepare request for daemon to read. */

  req.head.reqid = USRSOCK_REQUEST_ACCEPT;
  req.usockid = conn->usockid;
  req.max_addrlen = addrlen;

  bufs[0].iov_base = &req;
  bufs[0].iov_len = sizeof(req);

  return usrsockdev_do_request(conn, bufs, ARRAY_SIZE(bufs));
}

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: usrsock_accept
 *
 * Description:
 *   The usrsock_sockif_accept function is used with connection-based socket
 *   types (SOCK_STREAM, SOCK_SEQPACKET and SOCK_RDM). It extracts the first
 *   connection request on the queue of pending connections, creates a new
 *   connected socket with mostly the same properties as 'sockfd', and
 *   allocates a new socket descriptor for the socket, which is returned. The
 *   newly created socket is no longer in the listening state. The original
 *   socket 'sockfd' is unaffected by this call.  Per file descriptor flags
 *   are not inherited across an inet_accept.
 *
 *   The 'sockfd' argument is a socket descriptor that has been created with
 *   socket(), bound to a local address with bind(), and is listening for
 *   connections after a call to listen().
 *
 *   On return, the 'addr' structure is filled in with the address of the
 *   connecting entity. The 'addrlen' argument initially contains the size
 *   of the structure pointed to by 'addr'; on return it will contain the
 *   actual length of the address returned.
 *
 *   If no pending connections are present on the queue, and the socket is
 *   not marked as non-blocking, inet_accept blocks the caller until a
 *   connection is present. If the socket is marked non-blocking and no
 *   pending connections are present on the queue, inet_accept returns
 *   EAGAIN.
 *
 * Parameters:
 *   psock    Reference to the listening socket structure
 *   addr     Receives the address of the connecting client
 *   addrlen  Input: allocated size of 'addr', Return: returned size of 'addr'
 *   newsock  Location to return the accepted socket information.
 *
 * Returned Value:
 *   Returns 0 (OK) on success.  On failure, it returns a negated errno
 *   value.  See accept() for a description of the appropriate error value.
 *
 * Assumptions:
 *   The network is locked.
 *
 ****************************************************************************/

int usrsock_accept(FAR struct socket *psock, FAR struct sockaddr *addr,
                   FAR socklen_t *addrlen, FAR struct socket *newsock)
{
  FAR struct usrsock_conn_s *conn = psock->s_conn;
  struct usrsock_data_reqstate_s state = {};
  FAR struct usrsock_conn_s *newconn;
  struct iovec inbufs[2];
  socklen_t inaddrlen = 0;
  socklen_t outaddrlen = 0;
  int ret;
#ifdef CONFIG_NET_SOCKOPTS
  struct timespec abstime;
#endif
  struct timespec *ptimeo = NULL;

  DEBUGASSERT(conn);

  if (addrlen)
    {
      if (*addrlen > 0 && addr == NULL)
        {
          return -EINVAL;
        }

      inaddrlen = *addrlen;
    }

  net_lock();

  if (conn->state == USRSOCK_CONN_STATE_UNINITIALIZED ||
      conn->state == USRSOCK_CONN_STATE_ABORTED)
    {
      /* Invalid state or closed by daemon. */

      ninfo("usockid=%d; accept() with uninitialized usrsock.\n",
            conn->usockid);

      ret = (conn->state == USRSOCK_CONN_STATE_ABORTED) ? -EPIPE : -ECONNRESET;
      goto errout_unlock;
    }

  if (conn->state == USRSOCK_CONN_STATE_CONNECTING)
    {
      /* Connecting. */

      ninfo("usockid=%d; socket still connecting.\n",
            conn->usockid);

      ret = -EAGAIN;
      goto errout_unlock;
    }

  if (!conn->connected)
    {
      /* Not connected. */

      ninfo("usockid=%d; socket not connected.\n",
            conn->usockid);

      ret = -ENOTCONN;
      goto errout_unlock;
    }

  /* Allocate the usrsock socket connection structure and save in the new
   * socket instance.
   */

  newconn = usrsock_alloc();
  if (!newconn)
    {
      /* Failed to reserve a connection structure */

      ret = -ENOMEM;
      goto errout_unlock;
    }

#ifdef CONFIG_NET_SOCKOPTS
  if (psock->s_rcvtimeo != 0)
    {
      DEBUGVERIFY(clock_gettime(CLOCK_REALTIME, &abstime));

      /* Prepare timeout value for accept. */

      abstime.tv_sec += psock->s_rcvtimeo / DSEC_PER_SEC;
      abstime.tv_nsec += (psock->s_rcvtimeo % DSEC_PER_SEC) * NSEC_PER_DSEC;
      if (abstime.tv_nsec >= NSEC_PER_SEC)
        {
          abstime.tv_sec++;
          abstime.tv_nsec -= NSEC_PER_SEC;
        }

      ptimeo = &abstime;
    }
#endif

  do
    {
      /* Check if remote end has closed connection. */

      if (conn->flags & USRSOCK_EVENT_REMOTE_CLOSED)
        {
          ninfo("usockid=%d; remote closed (EOF).\n", conn->usockid);

          ret = -EPIPE;
          goto errout_free_conn;
        }

      /* Check if need to wait for connection to become available. */

      if (!(conn->flags & USRSOCK_EVENT_RECVFROM_AVAIL))
        {
          if (_SS_ISNONBLOCK(psock->s_flags))
            {
              /* Nothing to receive from daemon side. */

              ret = -EAGAIN;
              goto errout_free_conn;
            }

          /* Wait accept to become avail. */

          ret = usrsock_setup_data_request_callback(
              conn, &state, accept_event,
              USRSOCK_EVENT_ABORT | USRSOCK_EVENT_RECVFROM_AVAIL |
              USRSOCK_EVENT_REMOTE_CLOSED);
          if (ret < 0)
            {
              nwarn("usrsock_setup_request_callback failed: %d\n", ret);
              goto errout_free_conn;
            }

          /* Wait for receive-avail (or abort, or timeout, or signal). */

          ret = net_timedwait(&state.reqstate.recvsem, ptimeo);
          if (ret < 0)
            {
              if (ret == -ETIMEDOUT)
                {
                  ninfo("accept timedout\n");

                  ret = -EAGAIN;
                }
              else if (ret == -EINTR)
                {
                  ninfo("accept interrupted\n");
                }
              else
                {
                  nerr("net_timedwait errno: %d\n", ret);
                  DEBUGASSERT(false);
                }
            }

          usrsock_teardown_data_request_callback(&state);

          /* Did wait timeout or got signal? */

          if (ret != 0)
            {
              goto errout_free_conn;
            }

          /* Was socket aborted? */

          if (conn->state == USRSOCK_CONN_STATE_ABORTED)
            {
              ret = -EPIPE;
              goto errout_free_conn;
            }

          /* Did remote disconnect? */

          if (conn->flags & USRSOCK_EVENT_REMOTE_CLOSED)
            {
              ret = -EPIPE;
              goto errout_free_conn;
            }

          DEBUGASSERT(conn->flags & USRSOCK_EVENT_RECVFROM_AVAIL);
        }

      /* Set up event callback for usrsock. */

      ret = usrsock_setup_data_request_callback(
          conn, &state, accept_event,
          USRSOCK_EVENT_ABORT | USRSOCK_EVENT_REQ_COMPLETE);
      if (ret < 0)
        {
          nwarn("usrsock_setup_request_callback failed: %d\n", ret);
          goto errout_free_conn;
        }

      inbufs[0].iov_base = addr;
      inbufs[0].iov_len = inaddrlen;
      inbufs[1].iov_base = &newconn->usockid;
      inbufs[1].iov_len = sizeof(newconn->usockid);

      usrsock_setup_datain(conn, inbufs, ARRAY_SIZE(inbufs));

      /* We might start getting events for this socket right after
       * returning to daemon, so setup 'newconn' already here. */

      newconn->state = USRSOCK_CONN_STATE_READY;

      /* Request user-space daemon to accept socket. */

      ret = do_accept_request(conn, inaddrlen);
      if (ret >= 0)
        {
          /* Wait for completion of request. */

          while ((ret = net_lockedwait(&state.reqstate.recvsem)) < 0)
            {
              DEBUGASSERT(ret == -EINTR);
            }

          ret = state.reqstate.result;

          DEBUGASSERT(state.valuelen <= inaddrlen);
          DEBUGASSERT(state.valuelen <= state.valuelen_nontrunc);

          if (ret >= 0)
            {
              newconn->connected = true;
              newconn->type      = conn->type;
              newconn->crefs     = 1;

              newsock->s_type    = psock->s_type;
              newsock->s_domain  = psock->s_domain;
              newsock->s_conn    = newconn;
              newsock->s_sockif  = psock->s_sockif;

              /* Store length of 'from' address that was available at
               * daemon-side. */

              outaddrlen = state.valuelen_nontrunc;

              ret = OK;
            }
        }

      usrsock_teardown_datain(conn);
      usrsock_teardown_data_request_callback(&state);
    }
  while (ret == -EAGAIN);

  if (ret >= 0)
    {
      goto errout_unlock;
    }

errout_free_conn:
  usrsock_free(newconn);

errout_unlock:
  net_unlock();

  if (addrlen)
    {
      *addrlen = outaddrlen;
    }

  return ret;
}

#endif /* CONFIG_NET && CONFIG_NET_USRSOCK */