/****************************************************************************
 * net/usrsock/usrsock_sendmsg.c
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.  The
 * ASF licenses this file to you 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.
 *
 ****************************************************************************/

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

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

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

#include <arch/irq.h>

#include <sys/socket.h>
#include <nuttx/net/net.h>
#include <nuttx/net/usrsock.h>

#include "usrsock/usrsock.h"

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

static uint16_t sendto_event(FAR struct net_driver_s *dev,
                             FAR void *pvpriv, uint16_t flags)
{
  FAR struct usrsock_reqstate_s *pstate = pvpriv;
  FAR struct usrsock_conn_s *conn = pstate->conn;

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

      pstate->result = -ECONNABORTED;

      /* Stop further callbacks */

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

      /* Wake up the waiting thread */

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

      pstate->result = conn->resp.result;

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

          conn->flags &= ~USRSOCK_EVENT_SENDTO_READY;
        }

      /* Stop further callbacks */

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

      /* Wake up the waiting thread */

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

      pstate->result = -EPIPE;

      /* Stop further callbacks */

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

      /* Wake up the waiting thread */

      nxsem_post(&pstate->recvsem);
    }
  else if (flags & USRSOCK_EVENT_SENDTO_READY)
    {
      ninfo("sendto ready.\n");

      /* Do not let other waiters to claim new data. */

      flags &= ~USRSOCK_EVENT_SENDTO_READY;

      /* Stop further callbacks */

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

      /* Wake up the waiting thread */

      nxsem_post(&pstate->recvsem);
    }

  return flags;
}

/****************************************************************************
 * Name: do_sendto_request
 ****************************************************************************/

static int do_sendto_request(FAR struct usrsock_conn_s *conn,
                             FAR struct msghdr *msg, int flags)
{
  struct usrsock_request_sendto_s req =
  {
  };

  struct iovec bufs[2 + msg->msg_iovlen];
  int i;

  if (msg->msg_namelen > UINT16_MAX)
    {
      msg->msg_namelen = UINT16_MAX;
    }

  /* Prepare request for daemon to read. */

  req.head.reqid = USRSOCK_REQUEST_SENDTO;
  req.usockid = conn->usockid;
  req.flags = flags;
  req.addrlen = msg->msg_namelen;

  for (i = 0; i < msg->msg_iovlen; i++)
    {
      req.buflen += msg->msg_iov[i].iov_len;
    }

  if (req.buflen > UINT32_MAX)
    {
      req.buflen = UINT32_MAX;
    }

  bufs[0].iov_base = (FAR void *)&req;
  bufs[0].iov_len  = sizeof(req);
  bufs[1].iov_base = msg->msg_name;
  bufs[1].iov_len  = msg->msg_namelen;

  memcpy(&bufs[2], msg->msg_iov, sizeof(struct iovec) * msg->msg_iovlen);

  return usrsock_do_request(conn, bufs, nitems(bufs));
}

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

/****************************************************************************
 * Name: usrsock_sendmsg
 *
 * Description:
 *   If sendmsg() is used on a connection-mode (SOCK_STREAM, SOCK_SEQPACKET)
 *   socket, the parameters 'msg_name' and 'msg_namelen' are ignored (and the
 *   error EISCONN may be returned when they are not NULL and 0), and the
 *   error ENOTCONN is returned when the socket was not actually connected.
 *
 * Input Parameters:
 *   psock    A reference to the socket structure of the socket
 *   msg      Message to send
 *   flags    Send flags (ignored)
 *
 * Returned Value:
 *   On success, returns the number of characters sent.  On any failure, a
 *   negated errno value is returned.
 *
 ****************************************************************************/

ssize_t usrsock_sendmsg(FAR struct socket *psock,
                        FAR struct msghdr *msg, int flags)
{
  FAR struct usrsock_conn_s *conn = psock->s_conn;
  struct usrsock_reqstate_s state =
  {
  };

  ssize_t ret;

  net_lock();

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

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

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

  if (psock->s_type == SOCK_STREAM || psock->s_type == SOCK_SEQPACKET)
    {
      if (!conn->connected)
        {
          if (conn->state == USRSOCK_CONN_STATE_CONNECTING)
            {
              /* Connecting. */

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

              ret = -EAGAIN;
              goto errout_unlock;
            }
          else
            {
              /* Not connected. */

              ret = -ENOTCONN;
              goto errout_unlock;
            }
        }

      if (msg->msg_name || msg->msg_namelen)
        {
          /* Address provided for connection-mode socket */

          ret = -EISCONN;
          goto errout_unlock;
        }
    }

  if (conn->state == USRSOCK_CONN_STATE_CONNECTING)
    {
      /* Non-blocking connecting. */

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

      ret = -EAGAIN;
      goto errout_unlock;
    }

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

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

          ret = -EPIPE;
          goto errout_unlock;
        }

      /* Check if need to wait for send to become ready. */

      if (!(conn->flags & USRSOCK_EVENT_SENDTO_READY))
        {
          if (_SS_ISNONBLOCK(conn->sconn.s_flags) ||
              (flags & MSG_DONTWAIT) != 0)
            {
              /* Send busy at daemon side. */

              ret = -EAGAIN;
              goto errout_unlock;
            }

          /* Wait send to become ready. */

          ret = usrsock_setup_request_callback(conn, &state, sendto_event,
                                               USRSOCK_EVENT_ABORT |
                                               USRSOCK_EVENT_SENDTO_READY |
                                               USRSOCK_EVENT_REMOTE_CLOSED);
          if (ret < 0)
            {
              nwarn("usrsock_setup_request_callback failed: %zd\n", ret);
              goto errout_unlock;
            }

          /* Wait for send-ready (or abort, or timeout, or signal). */

          ret = net_sem_timedwait(&state.recvsem,
                              _SO_TIMEOUT(conn->sconn.s_sndtimeo));
          usrsock_teardown_request_callback(&state);
          if (ret < 0)
            {
              if (ret == -ETIMEDOUT)
                {
                  ninfo("sendto timedout\n");

                  ret = -EAGAIN;
                }
              else if (ret == -EINTR)
                {
                  ninfo("sendto interrupted\n");
                }
              else
                {
                  nerr("net_sem_timedwait errno: %zd\n", ret);
                  DEBUGPANIC();
                }

              goto errout_unlock;
            }

          /* Was socket aborted? */

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

          /* Did remote disconnect? */

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

          DEBUGASSERT(conn->flags & USRSOCK_EVENT_SENDTO_READY);
        }

      /* Set up event callback for usrsock. */

      ret = usrsock_setup_request_callback(conn, &state, sendto_event,
                                           USRSOCK_EVENT_ABORT |
                                           USRSOCK_EVENT_REQ_COMPLETE);
      if (ret < 0)
        {
          nwarn("usrsock_setup_request_callback failed: %zd\n", ret);
          goto errout_unlock;
        }

      /* MSG_DONTWAIT is only use in usrsock. */

       flags &= ~MSG_DONTWAIT;

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

      ret = do_sendto_request(conn, msg, flags);
      if (ret >= 0)
        {
          /* Wait for completion of request. */

          net_sem_wait_uninterruptible(&state.recvsem);
          ret = state.result;
        }

      usrsock_teardown_request_callback(&state);
    }
  while (ret == -EAGAIN);

errout_unlock:
  net_unlock();
  return ret;
}

#endif /* CONFIG_NET && CONFIG_NET_USRSOCK */