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incubator-nuttx/net/tcp/tcp_send_unbuffered.c

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/****************************************************************************
* net/tcp/tcp_send_unbuffered.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_TCP) && \
!defined(CONFIG_NET_TCP_WRITE_BUFFERS)
#include <sys/types.h>
#include <sys/socket.h>
#include <inttypes.h>
#include <stdint.h>
#include <stdbool.h>
#include <string.h>
#include <errno.h>
#include <assert.h>
#include <debug.h>
#include <arch/irq.h>
#include <nuttx/semaphore.h>
#include <nuttx/net/net.h>
#include <nuttx/net/netdev.h>
#include <nuttx/net/tcp.h>
#include "netdev/netdev.h"
#include "devif/devif.h"
#include "socket/socket.h"
#include "inet/inet.h"
#include "arp/arp.h"
#include "icmpv6/icmpv6.h"
#include "neighbor/neighbor.h"
#include "route/route.h"
#include "tcp/tcp.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* If both IPv4 and IPv6 support are both enabled, then we will need to build
* in some additional domain selection support.
*/
#if defined(CONFIG_NET_IPv4) && defined(CONFIG_NET_IPv6)
# define NEED_IPDOMAIN_SUPPORT 1
#endif
/****************************************************************************
* Private Types
****************************************************************************/
/* This structure holds the state of the send operation until it can be
* operated upon when the TX poll event occurs.
*/
struct send_s
{
FAR struct tcp_conn_s *snd_conn; /* The TCP connection of interest */
FAR struct devif_callback_s *snd_cb; /* Reference to callback instance */
sem_t snd_sem; /* Used to wake up the waiting thread */
FAR const uint8_t *snd_buffer; /* Points to the buffer of data to send */
size_t snd_buflen; /* Number of bytes in the buffer to send */
ssize_t snd_sent; /* The number of bytes sent */
uint32_t snd_isn; /* Initial sequence number */
uint32_t snd_acked; /* The number of bytes acked */
#ifdef CONFIG_NET_TCP_FAST_RETRANSMIT
uint32_t snd_prev_ack; /* The previous ACKed seq number */
#ifdef CONFIG_NET_TCP_WINDOW_SCALE
uint32_t snd_prev_wnd; /* The advertised window in the last
* incoming acknowledgment
*/
#else
uint16_t snd_prev_wnd;
#endif
int snd_dup_acks; /* Duplicate ACK counter */
#endif
};
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: tcpsend_eventhandler
*
* Description:
* This function is called to perform the actual send operation when
* polled by the lower, device interfacing layer.
*
* Input Parameters:
* dev The structure of the network driver that caused the event
* pvpriv An instance of struct send_s cast to void*
* flags Set of events describing why the callback was invoked
*
* Returned Value:
* None
*
* Assumptions:
* The network is locked.
*
****************************************************************************/
static uint16_t tcpsend_eventhandler(FAR struct net_driver_s *dev,
FAR void *pvpriv, uint16_t flags)
{
FAR struct send_s *pstate = pvpriv;
FAR struct tcp_conn_s *conn;
int ret;
DEBUGASSERT(pstate != NULL);
/* Get the TCP connection pointer reliably from
* the corresponding TCP socket.
*/
conn = pstate->snd_conn;
DEBUGASSERT(conn != NULL);
/* The TCP socket is connected and, hence, should be bound to a device.
* Make sure that the polling device is the one that we are bound to.
*/
DEBUGASSERT(conn->dev != NULL);
if (dev != conn->dev)
{
return flags;
}
ninfo("flags: %04x acked: %" PRId32 " sent: %zd\n",
flags, pstate->snd_acked, pstate->snd_sent);
/* The TCP_ACKDATA, TCP_REXMIT and TCP_DISCONN_EVENTS flags are expected to
* appear here strictly one at a time, except for the FIN + ACK case.
*/
DEBUGASSERT((flags & TCP_ACKDATA) == 0 ||
(flags & TCP_REXMIT) == 0);
DEBUGASSERT((flags & TCP_DISCONN_EVENTS) == 0 ||
(flags & TCP_REXMIT) == 0);
/* If this packet contains an acknowledgement, then update the count of
* acknowledged bytes.
* This condition is located here for performance reasons
* (TCP_ACKDATA is the most frequent event).
*/
if ((flags & TCP_ACKDATA) != 0)
{
uint32_t ackno;
FAR struct tcp_hdr_s *tcp;
/* Get the offset address of the TCP header */
#ifdef CONFIG_NET_IPv4
#ifdef CONFIG_NET_IPv6
if (conn->domain == PF_INET)
#endif
{
tcp = TCPIPv4BUF;
}
#endif /* CONFIG_NET_IPv4 */
#ifdef CONFIG_NET_IPv6
#ifdef CONFIG_NET_IPv4
else
#endif
{
tcp = TCPIPv6BUF;
}
#endif /* CONFIG_NET_IPv6 */
/* The current acknowledgement number is the (relative) offset of the
* next byte needed by the receiver. The snd_isn is the offset of the
* first byte to send to the receiver. The difference is the number
* of bytes to be acknowledged.
*/
ackno = tcp_getsequence(tcp->ackno);
pstate->snd_acked = TCP_SEQ_SUB(ackno,
pstate->snd_isn);
ninfo("ACK: acked=%" PRId32 " sent=%zd buflen=%zu\n",
pstate->snd_acked, pstate->snd_sent, pstate->snd_buflen);
/* Have all of the bytes in the buffer been sent and acknowledged? */
if (pstate->snd_acked >= pstate->snd_buflen)
{
/* Yes. Then pstate->snd_buflen should hold the number of bytes
* actually sent.
*/
goto end_wait;
}
#ifdef CONFIG_NET_TCP_FAST_RETRANSMIT
/* Fast Retransmit (RFC 5681): an acknowledgment is considered a
* "duplicate" when (a) the receiver of the ACK has outstanding data,
* (b) the incoming acknowledgment carries no data, (c) the SYN and
* FIN bits are both off, (d) the acknowledgment number is equal to
* the greatest acknowledgment received on the given connection
* and (e) the advertised window in the incoming acknowledgment equals
* the advertised window in the last incoming acknowledgment.
*/
if (pstate->snd_acked < pstate->snd_sent &&
(flags & TCP_NEWDATA) == 0 &&
(tcp->flags & (TCP_SYN | TCP_FIN)) == 0 &&
ackno == pstate->snd_prev_ack &&
conn->snd_wnd == pstate->snd_prev_wnd)
{
if (++pstate->snd_dup_acks >= TCP_FAST_RETRANSMISSION_THRESH)
{
flags |= TCP_REXMIT;
pstate->snd_dup_acks = 0;
}
}
else
{
pstate->snd_dup_acks = 0;
}
pstate->snd_prev_ack = ackno;
pstate->snd_prev_wnd = conn->snd_wnd;
#endif
}
/* Check if we are being asked to retransmit data.
* This condition is located here after TCP_ACKDATA for performance reasons
* (TCP_REXMIT is less frequent than TCP_ACKDATA).
*/
if ((flags & TCP_REXMIT) != 0)
{
uint32_t sndlen;
nwarn("WARNING: TCP_REXMIT\n");
/* According to RFC 6298 (5.4), retransmit the earliest segment
* that has not been acknowledged by the TCP receiver.
*/
/* Reconstruct the length of the earliest segment to be retransmitted */
sndlen = pstate->snd_buflen - pstate->snd_acked;
if (sndlen > conn->mss)
{
sndlen = conn->mss;
}
conn->rexmit_seq = pstate->snd_isn + pstate->snd_acked;
#ifdef NEED_IPDOMAIN_SUPPORT
/* If both IPv4 and IPv6 support are enabled, then we will need to
* select which one to use when generating the outgoing packet.
* If only one domain is selected, then the setup is already in
* place and we need do nothing.
*/
tcp_ip_select(conn);
#endif
/* Then set-up to send that amount of data. (this won't actually
* happen until the polling cycle completes).
*/
ret = devif_send(dev, &pstate->snd_buffer[pstate->snd_acked],
sndlen, tcpip_hdrsize(conn));
if (ret <= 0)
{
pstate->snd_sent = ret;
goto end_wait;
}
/* Continue waiting */
return flags;
}
/* Check for a loss of connection.
* This condition is located here after both the TCP_ACKDATA and TCP_REXMIT
* because TCP_DISCONN_EVENTS is the least frequent event.
*/
else if ((flags & TCP_DISCONN_EVENTS) != 0)
{
ninfo("Lost connection\n");
/* We could get here recursively through the callback actions of
* tcp_lost_connection(). So don't repeat that action if we have
* already been disconnected.
*/
if (_SS_ISCONNECTED(conn->sconn.s_flags))
{
/* Report not connected */
tcp_lost_connection(conn, pstate->snd_cb, flags);
}
pstate->snd_sent = -ENOTCONN;
goto end_wait;
}
/* Check if the outgoing packet is available (it may have been claimed
* by a sendto event serving a different thread).
*/
#if 0 /* We can't really support multiple senders on the same TCP socket */
else if (dev->d_sndlen > 0)
{
/* Another thread has beat us sending data, wait for the next poll */
return flags;
}
#endif
/* We get here if (1) not all of the data has been ACKed, (2) we have been
* asked to retransmit data, (3) the connection is still healthy, and (4)
* the outgoing packet is available for our use. In this case, we are
* now free to send more data to receiver -- UNLESS the buffer contains
* unprocessed incoming data. In that event, we will have to wait for the
* next polling cycle.
*/
if ((flags & TCP_NEWDATA) == 0 && pstate->snd_sent < pstate->snd_buflen)
{
/* Get the amount of data that we can send in the next packet */
uint32_t sndlen = pstate->snd_buflen - pstate->snd_sent;
if (sndlen > conn->mss)
{
sndlen = conn->mss;
}
/* Check if we have "space" in the window */
if ((pstate->snd_sent - pstate->snd_acked + sndlen) < conn->snd_wnd)
{
#ifdef NEED_IPDOMAIN_SUPPORT
/* If both IPv4 and IPv6 support are enabled, then we will need to
* select which one to use when generating the outgoing packet.
* If only one domain is selected, then the setup is already in
* place and we need do nothing.
*/
tcp_ip_select(conn);
#endif
/* Then set-up to send that amount of data. (this won't actually
* happen until the polling cycle completes).
*/
ret = devif_send(dev, &pstate->snd_buffer[pstate->snd_sent],
sndlen, tcpip_hdrsize(conn));
if (ret <= 0)
{
pstate->snd_sent = ret;
goto end_wait;
}
/* Update the amount of data sent (but not necessarily ACKed) */
pstate->snd_sent += sndlen;
ninfo("SEND: acked=%" PRId32 " sent=%zd buflen=%zu\n",
pstate->snd_acked, pstate->snd_sent, pstate->snd_buflen);
}
else
{
nwarn("WARNING: Window full, wait for ack\n");
}
}
/* Continue waiting */
return flags;
end_wait:
/* Do not allow any further callbacks */
DEBUGASSERT(pstate->snd_cb != NULL);
pstate->snd_cb->flags = 0;
pstate->snd_cb->priv = NULL;
pstate->snd_cb->event = NULL;
/* There are no outstanding, unacknowledged bytes */
conn->tx_unacked = 0;
/* Wake up the waiting thread */
nxsem_post(&pstate->snd_sem);
return flags;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: psock_tcp_send
*
* Description:
* psock_tcp_send() call may be used only when the TCP socket is in a
* connected state (so that the intended recipient is known).
*
* 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 error,
* a negated errno value is returned.
*
* 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.
* 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.
*
****************************************************************************/
ssize_t psock_tcp_send(FAR struct socket *psock,
FAR const void *buf, size_t len, int flags)
{
FAR struct tcp_conn_s *conn;
struct send_s state;
int ret = OK;
/* Verify that the sockfd corresponds to valid, allocated socket */
if (psock == NULL || psock->s_type != SOCK_STREAM ||
psock->s_conn == NULL)
{
nerr("ERROR: Invalid socket\n");
ret = -EBADF;
goto errout;
}
conn = psock->s_conn;
/* Check early if this is an un-connected socket, if so, then
* return -ENOTCONN. Note, we will have to check this again, as we can't
* guarantee the state won't change until we have the network locked.
*/
if (!_SS_ISCONNECTED(conn->sconn.s_flags))
{
nerr("ERROR: Not connected\n");
ret = -ENOTCONN;
goto errout;
}
/* Make sure that we have the IP address mapping */
#if defined(CONFIG_NET_ARP_SEND) || defined(CONFIG_NET_ICMPv6_NEIGHBOR)
#ifdef CONFIG_NET_ARP_SEND
if (psock->s_domain == PF_INET)
{
/* Make sure that the IP address mapping is in the ARP table */
ret = arp_send(conn->u.ipv4.raddr);
}
#endif /* CONFIG_NET_ARP_SEND */
#ifdef CONFIG_NET_ICMPv6_NEIGHBOR
if (psock->s_domain == PF_INET6)
{
/* Make sure that the IP address mapping is in the Neighbor Table */
ret = icmpv6_neighbor(NULL, conn->u.ipv6.raddr);
}
#endif /* CONFIG_NET_ICMPv6_NEIGHBOR */
/* Did we successfully get the address mapping? */
if (ret < 0)
{
nerr("ERROR: Not reachable\n");
ret = -ENETUNREACH;
goto errout;
}
#endif /* CONFIG_NET_ARP_SEND || CONFIG_NET_ICMPv6_NEIGHBOR */
/* Perform the TCP send operation */
/* Initialize the state structure. This is done with the network
* locked because we don't want anything to happen until we are
* ready.
*/
net_lock();
/* Now that we have the network locked, we need to check the connection
* state again to ensure the connection is still valid.
*/
if (!_SS_ISCONNECTED(conn->sconn.s_flags))
{
nerr("ERROR: No longer connected\n");
net_unlock();
ret = -ENOTCONN;
goto errout;
}
memset(&state, 0, sizeof(struct send_s));
nxsem_init(&state.snd_sem, 0, 0); /* Doesn't really fail */
state.snd_conn = conn; /* Socket descriptor to use */
state.snd_buflen = len; /* Number of bytes to send */
state.snd_buffer = buf; /* Buffer to send from */
if (len > 0)
{
/* Allocate resources to receive a callback */
ret = -ENOMEM; /* Assume allocation failure */
state.snd_cb = tcp_callback_alloc(conn);
if (state.snd_cb)
{
/* Get the initial sequence number that will be used */
state.snd_isn = tcp_getsequence(conn->sndseq);
/* There is no outstanding, unacknowledged data after this
* initial sequence number.
*/
conn->tx_unacked = 0;
/* Set up the callback in the connection */
state.snd_cb->flags = (TCP_ACKDATA | TCP_REXMIT | TCP_POLL |
TCP_DISCONN_EVENTS);
state.snd_cb->priv = (FAR void *)&state;
state.snd_cb->event = tcpsend_eventhandler;
/* Notify the device driver of the availability of TX data */
tcp_send_txnotify(psock, conn);
/* Wait for the send to complete or an error to occur: NOTES:
* net_sem_wait will also terminate if a signal is received.
*/
for (; ; )
{
uint32_t acked = state.snd_acked;
ret = net_sem_timedwait(&state.snd_sem,
_SO_TIMEOUT(conn->sconn.s_sndtimeo));
if (ret != -ETIMEDOUT || acked == state.snd_acked)
{
if (ret == -ETIMEDOUT)
{
ret = -EAGAIN;
}
break; /* Timeout without any progress */
}
}
/* Make sure that no further events are processed */
tcp_callback_free(conn, state.snd_cb);
}
}
nxsem_destroy(&state.snd_sem);
net_unlock();
/* Check for a errors. Errors are signalled by negative errno values
* for the send length
*/
if (state.snd_sent < 0)
{
ret = state.snd_sent;
goto errout;
}
/* If net_sem_timedwait failed, then we were probably reawakened by a
* signal. In this case, net_sem_timedwait will have returned negated
* errno appropriately.
*/
if (ret < 0)
{
goto errout;
}
/* Return the number of bytes actually sent */
ret = state.snd_sent;
errout:
return ret;
}
/****************************************************************************
* Name: psock_tcp_cansend
*
* Description:
* psock_tcp_cansend() returns a value indicating if a write to the socket
* would block. It is still possible that the write may block if another
* write occurs first.
*
* Input Parameters:
* conn The TCP connection of interest
*
* Returned Value:
* OK (Always can send).
*
* Assumptions:
* None
*
****************************************************************************/
int psock_tcp_cansend(FAR struct tcp_conn_s *conn)
{
return OK;
}
#endif /* CONFIG_NET && CONFIG_NET_TCP && !CONFIG_NET_TCP_WRITE_BUFFERS */
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