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incubator-nuttx/net/tcp/tcp_netpoll.c

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/****************************************************************************
* net/tcp/tcp_netpoll.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 <stdint.h>
#include <assert.h>
#include <poll.h>
#include <debug.h>
#include <nuttx/net/net.h>
#include <nuttx/net/tcp.h>
#include <nuttx/semaphore.h>
#include "devif/devif.h"
#include "netdev/netdev.h"
#include "socket/socket.h"
#include "inet/inet.h"
#include "tcp/tcp.h"
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: tcp_poll_eventhandler
*
* Description:
* This function is called to perform the actual TCP receive operation via
* the device interface layer.
*
* Input Parameters:
* dev The structure of the network driver that caused the event
* conn The connection structure associated with the socket
* flags Set of events describing why the callback was invoked
*
* Returned Value:
* None
*
* Assumptions:
* The network is locked
*
****************************************************************************/
static uint16_t tcp_poll_eventhandler(FAR struct net_driver_s *dev,
FAR void *conn,
FAR void *pvpriv, uint16_t flags)
{
FAR struct tcp_poll_s *info = (FAR struct tcp_poll_s *)pvpriv;
int reason;
ninfo("flags: %04x\n", flags);
DEBUGASSERT(info == NULL || (info->conn != NULL && info->fds != NULL));
/* 'priv' might be null in some race conditions (?) */
if (info != NULL)
{
pollevent_t eventset = 0;
/* Check for data or connection availability events. */
if ((flags & (TCP_NEWDATA | TCP_BACKLOG)) != 0)
{
eventset |= POLLIN & info->fds->events;
}
/* Non-blocking connection */
if ((flags & TCP_CONNECTED) != 0)
{
eventset |= POLLOUT & info->fds->events;
}
/* Check for a loss of connection events. */
if ((flags & TCP_DISCONN_EVENTS) != 0)
{
/* TCP_TIMEDOUT: Connection aborted due to too many
* retransmissions.
*/
if ((flags & TCP_TIMEDOUT) != 0)
{
/* Indicate that the connection timedout?) */
reason = ETIMEDOUT;
}
else if ((flags & NETDEV_DOWN) != 0)
{
/* The network device went down. Indicate that the remote host
* is unreachable.
*/
reason = ENETUNREACH;
}
/* TCP_CLOSE: The remote host has closed the connection
* TCP_ABORT: The remote host has aborted the connection
*/
else
{
/* Indicate that remote host refused the connection */
reason = ECONNREFUSED;
}
#ifdef CONFIG_NET_SOCKOPTS
info->conn->sconn.s_error = reason;
#endif
set_errno(reason);
/* Mark that the connection has been lost */
tcp_lost_connection(info->conn, info->cb, flags);
eventset |= (POLLERR | POLLHUP);
}
/* A poll is a sign that we are free to send data. */
/* Wake up poll() speculatively on TCP_ACKDATA.
* Note: our event handler is usually executed before
* psock_send_eventhandler, which might free IOBs/WRBs on TCP_ACKDATA.
* Revisit: consider some kind of priority for devif callback to allow
* this callback to be inserted after psock_send_eventhandler.
*/
else if (psock_tcp_cansend(info->conn) >= 0
#if defined(CONFIG_NET_TCP_WRITE_BUFFERS)
|| (flags & TCP_ACKDATA) != 0
#endif
)
{
eventset |= (POLLOUT & info->fds->events);
}
/* Awaken the caller of poll() if requested event occurred. */
if (eventset != 0)
{
/* Stop further callbacks */
info->cb->flags = 0;
info->cb->priv = NULL;
info->cb->event = NULL;
info->fds->revents |= eventset;
nxsem_post(info->fds->sem);
}
}
return flags;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: tcp_pollsetup
*
* Description:
* Setup to monitor events on one TCP/IP socket
*
* Input Parameters:
* psock - The TCP/IP socket of interest
* fds - The structure describing the events to be monitored, OR NULL if
* this is a request to stop monitoring events.
*
* Returned Value:
* 0: Success; Negated errno on failure
*
****************************************************************************/
int tcp_pollsetup(FAR struct socket *psock, FAR struct pollfd *fds)
{
FAR struct tcp_conn_s *conn;
FAR struct tcp_poll_s *info;
FAR struct devif_callback_s *cb;
bool nonblock_conn;
int ret = OK;
/* Some of the following must be atomic */
net_lock();
conn = psock->s_conn;
/* Sanity check */
if (!conn || !fds)
{
ret = -EINVAL;
goto errout_with_lock;
}
/* Non-blocking connection ? */
nonblock_conn = (conn->tcpstateflags == TCP_SYN_SENT &&
_SS_ISNONBLOCK(conn->sconn.s_flags));
/* Find a container to hold the poll information */
info = conn->pollinfo;
while (info->conn != NULL)
{
if (++info >= &conn->pollinfo[CONFIG_NET_TCP_NPOLLWAITERS])
{
ret = -ENOMEM;
goto errout_with_lock;
}
}
/* Allocate a TCP/IP callback structure */
cb = tcp_callback_alloc(conn);
if (!cb)
{
ret = -EBUSY;
goto errout_with_lock;
}
/* Initialize the poll info container */
info->conn = conn;
info->fds = fds;
info->cb = cb;
/* Initialize the callback structure. Save the reference to the info
* structure as callback private data so that it will be available during
* callback processing.
*/
cb->flags = TCP_DISCONN_EVENTS;
cb->priv = (FAR void *)info;
cb->event = tcp_poll_eventhandler;
if ((fds->events & POLLOUT) != 0)
{
cb->flags |= TCP_POLL
#if defined(CONFIG_NET_TCP_WRITE_BUFFERS)
| TCP_ACKDATA
#endif
;
/* Monitor the connected event */
if (nonblock_conn)
{
cb->flags |= TCP_CONNECTED;
}
}
if ((fds->events & POLLIN) != 0)
{
cb->flags |= TCP_NEWDATA | TCP_BACKLOG;
}
/* Save the reference in the poll info structure as fds private as well
* for use during poll teardown as well.
*/
fds->priv = (FAR void *)info;
/* Check for read data or backlogged connection availability now */
if (conn->readahead != NULL || tcp_backlogavailable(conn))
{
/* Normal data may be read without blocking. */
fds->revents |= (POLLRDNORM & fds->events);
}
/* Check for a loss of connection events. We need to be careful here.
* There are four possibilities:
*
* 1) The socket is connected and we are waiting for data availability
* events.
*
* __SS_ISCONNECTED(f) == true
* __SS_ISLISTENING(f) == false
* __SS_ISCLOSED(f) == false
*
* Action: Wait for data availability events
*
* 2) This is a listener socket that was never connected and we are
* waiting for connection events.
*
* __SS_ISCONNECTED(f) == false
* __SS_ISLISTENING(f) == true
* __SS_ISCLOSED(f) == false
*
* Action: Wait for connection events
*
* 3) This socket was previously connected, but the peer has gracefully
* closed the connection.
*
* __SS_ISCONNECTED(f) == false
* __SS_ISLISTENING(f) == false
* __SS_ISCLOSED(f) == true
*
* Action: Return with POLLHUP|POLLERR events
*
* 4) This socket was previously connected, but we lost the connection
* due to some exceptional event.
*
* __SS_ISCONNECTED(f) == false
* __SS_ISLISTENING(f) == false
* __SS_ISCLOSED(f) == false
*
* Action: Return with POLLHUP|POLLERR events
*/
if (!nonblock_conn && !_SS_ISCONNECTED(conn->sconn.s_flags) &&
!_SS_ISLISTENING(conn->sconn.s_flags))
{
/* We were previously connected but lost the connection either due
* to a graceful shutdown by the remote peer or because of some
* exceptional event.
*/
fds->revents |= (POLLERR | POLLHUP);
}
else if (_SS_ISCONNECTED(conn->sconn.s_flags) &&
psock_tcp_cansend(conn) >= 0)
{
fds->revents |= (POLLWRNORM & fds->events);
}
/* Check if any requested events are already in effect */
if (fds->revents != 0)
{
/* Yes.. then signal the poll logic */
nxsem_post(fds->sem);
}
errout_with_lock:
net_unlock();
return ret;
}
/****************************************************************************
* Name: tcp_pollteardown
*
* Description:
* Teardown monitoring of events on an TCP/IP socket
*
* Input Parameters:
* psock - The TCP/IP socket of interest
* fds - The structure describing the events to be monitored, OR NULL if
* this is a request to stop monitoring events.
*
* Returned Value:
* 0: Success; Negated errno on failure
*
****************************************************************************/
int tcp_pollteardown(FAR struct socket *psock, FAR struct pollfd *fds)
{
FAR struct tcp_conn_s *conn;
FAR struct tcp_poll_s *info;
/* Some of the following must be atomic */
net_lock();
conn = psock->s_conn;
/* Sanity check */
if (!conn || !fds->priv)
{
net_unlock();
return -EINVAL;
}
/* Recover the socket descriptor poll state info from the poll structure */
info = (FAR struct tcp_poll_s *)fds->priv;
DEBUGASSERT(info->fds != NULL && info->cb != NULL);
if (info != NULL)
{
/* Release the callback */
tcp_callback_free(conn, info->cb);
/* Release the poll/select data slot */
info->fds->priv = NULL;
/* Then free the poll info container */
info->conn = NULL;
}
net_unlock();
return OK;
}
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