/****************************************************************************
 * net/socket/send.c
 *
 * 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>

#include <sys/types.h>
#include <sys/socket.h>
#include <errno.h>
#include <assert.h>
#include <debug.h>

#include <nuttx/cancelpt.h>
#include <nuttx/net/net.h>

#include "socket/socket.h"

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

/****************************************************************************
 * Name: psock_send
 *
 * Description:
 *   The psock_send() call may be used only when the socket is in a
 *   connected state (so that the intended recipient is known).  This is an
 *   internal OS interface.  It is functionally equivalent to send() except
 *   that:
 *
 *   - It is not a cancellation point,
 *   - It does not modify the errno variable, and
 *   - I accepts the internal socket structure as an input rather than an
 *     task-specific socket descriptor.
 *
 *   See comments with send() for more a more complete description of the
 *   functionality.
 *
 * Input Parameters:
 *   psock    An instance of the internal socket structure.
 *   buf      Data to send
 *   len      Length of data to send
 *   flags    Send flags
 *
 * Returned Value:
 *   On success, returns the number of characters sent.  On any failure, a
 *   negated errno value is returned (See comments with send() for a list
 *   of the appropriate errno value).
 *
 ****************************************************************************/

ssize_t psock_send(FAR struct socket *psock, FAR const void *buf, size_t len,
                   int flags)
{
  struct msghdr msg;
  struct iovec iov;

  iov.iov_base = (FAR void *)buf;
  iov.iov_len = len;
  msg.msg_name = NULL;
  msg.msg_namelen = 0;
  msg.msg_iov = &iov;
  msg.msg_iovlen = 1;
  msg.msg_control = NULL;
  msg.msg_controllen = 0;
  msg.msg_flags = 0;

  /* And let psock_sendmsg do all of the work */

  return psock_sendmsg(psock, &msg, flags);
}

/****************************************************************************
 * Name: send
 *
 * Description:
 *   The send() call may be used only when the socket is in a connected state
 *   (so that the intended recipient is known). The only difference between
 *   send() and write() is the presence of flags. With zero flags parameter,
 *   send() is equivalent to write(). Also, send(sockfd,buf,len,flags) is
 *   equivalent to sendto(sockfd,buf,len,flags,NULL,0).
 *
 * Input Parameters:
 *   sockfd   Socket descriptor of the socket
 *   buf      Data to send
 *   len      Length of data to send
 *   flags    Send flags
 *
 * Returned Value:
 *   On success, returns the number of characters sent.  On  error,
 *   -1 is returned, and errno is set appropriately:
 *
 *   EAGAIN or EWOULDBLOCK
 *     The socket is marked non-blocking and the requested operation
 *     would block.
 *   EBADF
 *     An invalid descriptor was specified.
 *   ECONNRESET
 *     Connection reset by peer.
 *   EDESTADDRREQ
 *     The socket is not connection-mode, and no peer address is set.
 *   EFAULT
 *      An invalid user space address was specified for a parameter.
 *   EINTR
 *      A signal occurred before any data was transmitted.
 *   EINVAL
 *      Invalid argument passed.
 *   EISCONN
 *     The connection-mode socket was connected already but a recipient
 *     was specified. (Now either this error is returned, or the recipient
 *     specification is ignored.)
 *   EMSGSIZE
 *     The socket type requires that message be sent atomically, and the
 *     size of the message to be sent made this impossible.
 *   ENOBUFS
 *     The output queue for a network interface was full. This generally
 *     indicates that the interface has stopped sending, but may be
 *     caused by transient congestion.
 *   ENOMEM
 *     No memory available.
 *   ENOTCONN
 *     The socket is not connected, and no target has been given.
 *   ENOTSOCK
 *     The argument s is not a socket.
 *   EOPNOTSUPP
 *     Some bit in the flags argument is inappropriate for the socket
 *     type.
 *   EPIPE
 *     The local end has been shut down on a connection oriented socket.
 *     In this case the process will also receive a SIGPIPE unless
 *     MSG_NOSIGNAL is set.
 *
 * Assumptions:
 *
 ****************************************************************************/

ssize_t send(int sockfd, FAR const void *buf, size_t len, int flags)
{
  FAR struct socket *psock;
  ssize_t ret;

  /* send() is a cancellation point */

  enter_cancellation_point();

  /* Get the underlying socket structure */

  ret = sockfd_socket(sockfd, &psock);

  /* And let psock_send do all of the work */

  if (ret == OK)
    {
      ret = psock_send(psock, buf, len, flags);
    }

  if (ret < 0)
    {
      _SO_SETERRNO(psock, -ret);
      ret = ERROR;
    }

  leave_cancellation_point();
  return ret;
}