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nuttx/net/udp/udp_psock_sendto_buffered.c

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/****************************************************************************
* net/udp/udp_send_buffered.c
*
* Copyright (C) 2018 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* 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_UDP) && \
defined(CONFIG_NET_UDP_WRITE_BUFFERS)
#if defined(CONFIG_DEBUG_FEATURES) && defined(CONFIG_NET_UDP_WRBUFFER_DEBUG)
/* Force debug output (from this file only) */
# undef CONFIG_DEBUG_NET
# define CONFIG_DEBUG_NET 1
#endif
#include <sys/types.h>
#include <sys/socket.h>
#include <stdint.h>
#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <debug.h>
#include <debug.h>
#include <arch/irq.h>
#include <nuttx/clock.h>
#include <nuttx/net/net.h>
#include <nuttx/mm/iob.h>
#include <nuttx/net/netdev.h>
#include <nuttx/net/arp.h>
#include <nuttx/net/udp.h>
#include "netdev/netdev.h"
#include "socket/socket.h"
#include "inet/inet.h"
#include "arp/arp.h"
#include "icmpv6/icmpv6.h"
#include "neighbor/neighbor.h"
#include "udp/udp.h"
#include "devif/devif.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
#define UDPIPv4BUF ((struct udp_hdr_s *)&dev->d_buf[NET_LL_HDRLEN(dev) + IPv4_HDRLEN])
#define UDPIPv6BUF ((struct udp_hdr_s *)&dev->d_buf[NET_LL_HDRLEN(dev) + IPv6_HDRLEN])
/* Debug */
#ifdef CONFIG_NET_UDP_WRBUFFER_DUMP
# define BUF_DUMP(msg,buf,len) lib_dumpbuffer(msg,buf,len)
#else
# define BUF_DUMP(msg,buf,len)
# undef UDP_WBDUMP
# define UDP_WBDUMP(msg,wrb,len,offset)
#endif
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
#ifdef NEED_IPDOMAIN_SUPPORT
static inline void sendto_ipselect(FAR struct net_driver_s *dev,
FAR struct udp_conn_s *conn);
#endif
#ifdef CONFIG_NET_ETHERNET
static inline bool sendto_addrcheck(FAR struct udp_conn_s *conn,
FAR struct net_driver_s *dev);
#else
# define sendto_addrcheck(c,d) (true)
#endif
#ifdef CONFIG_NET_SOCKOPTS
static inline int sendto_timeout(FAR struct socket *psock,
FAR struct udp_conn_s *conn);
#endif
static int sendto_next_transfer(FAR struct socket *psock,
FAR struct udp_conn_s *conn);
static uint16_t sendto_eventhandler(FAR struct net_driver_s *dev,
FAR void *pvconn, FAR void *pvpriv,
uint16_t flags);
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: sendto_writebuffer_release
*
* Description:
* Release the write buffer at the head of the write buffer queue.
*
* Input Parameters:
* dev - The structure of the network driver that caused the event
* psock - Socket state structure
*
* Returned Value:
* None
*
* Assumptions:
* The network is locked
*
****************************************************************************/
static void sendto_writebuffer_release(FAR struct socket *psock,
FAR struct udp_conn_s *conn)
{
FAR struct udp_wrbuffer_s *wrb;
int ret = OK;
do
{
/* Check if the write queue became empty */
if (sq_empty(&conn->write_q))
{
/* Yes.. stifle any further callbacks until more write data is
* enqueued.
*/
psock->s_sndcb->flags = 0;
psock->s_sndcb->priv = NULL;
psock->s_sndcb->event = NULL;
wrb = NULL;
#ifdef CONFIG_TCP_NOTIFIER
/* Notify any waiters that the write buffers have been drained. */
udp_writebuffer_signal(conn);
#endif
}
else
{
/* Remove the write buffer from the head of the write buffer queue
* and release it.
*/
wrb = (FAR struct udp_wrbuffer_s *)sq_remfirst(&conn->write_q);
DEBUGASSERT(wrb != NULL);
udp_wrbuffer_release(wrb);
/* Set up for the next packet transfer by setting the connection
* address to the address of the next packet now at the header of
* the write buffer queue.
*/
ret = sendto_next_transfer(psock, conn);
}
}
while (wrb != NULL && ret < 0);
}
/****************************************************************************
* Name: sendto_ipselect
*
* Description:
* 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.
*
* Input Parameters:
* dev - The structure of the network driver that caused the event
* psock - Socket state structure
*
* Returned Value:
* None
*
* Assumptions:
* The network is locked
*
****************************************************************************/
#ifdef NEED_IPDOMAIN_SUPPORT
static inline void sendto_ipselect(FAR struct net_driver_s *dev,
FAR struct udp_conn_s *conn)
{
/* Which domain the socket support */
if (conn->domain == PF_INET)
{
/* Select the IPv4 domain */
udp_ipv4_select(dev);
}
else /* if (conn->domain == PF_INET6) */
{
/* Select the IPv6 domain */
DEBUGASSERT(conn->domain == PF_INET6);
udp_ipv6_select(dev);
}
}
#endif
/****************************************************************************
* Name: sendto_addrcheck
*
* Description:
* Check if the destination IP address is in the IPv4 ARP or IPv6 Neighbor
* tables. If not, then the send won't actually make it out... it will be
* replaced with an ARP request (IPv4) or a Neighbor Solicitation (IPv6).
*
* NOTE 1: This could be an expensive check if there are a lot of
* entries in the ARP or Neighbor tables.
*
* NOTE 2: If we are actually harvesting IP addresses on incoming IP
* packets, then this check should not be necessary; the MAC mapping
* should already be in the ARP table in many cases (IPv4 only).
*
* NOTE 3: If CONFIG_NET_ARP_SEND then we can be assured that the IP
* address mapping is already in the ARP table.
*
* Input Parameters:
* conn - The UDP connection structure
* dev - Polling network device
*
* Returned Value:
* true - The Ethernet MAC address is in the ARP or Neighbor table (OR
* the network device is not Ethernet).
*
* Assumptions:
* The network is locked
*
****************************************************************************/
#ifdef CONFIG_NET_ETHERNET
static inline bool sendto_addrcheck(FAR struct udp_conn_s *conn,
FAR struct net_driver_s *dev)
{
/* REVISIT: Could the MAC address not also be in a routing table? */
if (dev->d_lltype != NET_LL_ETHERNET)
{
return true;
}
#ifdef CONFIG_NET_IPv4
#ifdef CONFIG_NET_IPv6
if (conn->domain == PF_INET)
#endif
{
#if !defined(CONFIG_NET_ARP_IPIN) && !defined(CONFIG_NET_ARP_SEND)
return (arp_find(conn->u.ipv4.raddr, NULL) >= 0);
#else
return true;
#endif
}
#endif /* CONFIG_NET_IPv4 */
#ifdef CONFIG_NET_IPv6
#ifdef CONFIG_NET_IPv4
else
#endif
{
#if !defined(CONFIG_NET_ICMPv6_NEIGHBOR)
return (neighbor_lookup(conn->u.ipv6.raddr, NULL) >= 0);
#else
return true;
#endif
}
#endif /* CONFIG_NET_IPv6 */
}
#endif /* CONFIG_NET_ETHERNET */
/****************************************************************************
* Name: sendto_timeout
*
* Description:
* Check for send timeout.
*
* Input Parameters:
* pstate - sendto state structure
*
* Returned Value:
* TRUE:timeout FALSE:no timeout
*
* Assumptions:
* The network is locked
*
****************************************************************************/
#ifdef CONFIG_NET_SOCKOPTS
static inline int sendto_timeout(FAR struct socket *psock,
FAR struct udp_conn_s *conn)
{
FAR struct udp_wrbuffer_s *wrb;
/* Peek at the head of the write queue (without altering the write queue). */
wrb = (FAR struct udp_wrbuffer_s *)sq_peek(&conn->write_q);
if (wrb != NULL)
{
/* Check for a timeout configured via setsockopts(SO_SNDTIMEO).
* If none... we well let the send wait forever.
*/
if (psock->s_sndtimeo != 0)
{
/* Check if the configured timeout has elapsed */
return net_timeo(wrb->wb_start, psock->s_sndtimeo);
}
}
/* No timeout */
return FALSE;
}
#endif /* CONFIG_NET_SOCKOPTS */
/****************************************************************************
* Name: sendto_next_transfer
*
* Description:
* Setup for the next packet transfer
*
* Input Parameters:
* psock - Socket state structure
* conn - The UDP connection structure
*
* Returned Value:
* None
*
****************************************************************************/
static int sendto_next_transfer(FAR struct socket *psock,
FAR struct udp_conn_s *conn)
{
FAR struct udp_wrbuffer_s *wrb;
FAR struct net_driver_s *dev;
int ret;
/* Set the UDP "connection" to the destination address of the write buffer
* at the head of the queue.
*/
wrb = (FAR struct udp_wrbuffer_s *)sq_peek(&conn->write_q);
if (wrb == NULL)
{
ninfo("Write buffer queue is empty\n");
return -ENOENT;
}
ret = udp_connect(conn, (FAR const struct sockaddr *)&wrb->wb_dest);
if (ret < 0)
{
nerr("ERROR: udp_connect failed: %d\n", ret);
return ret;
}
/* Get the device that will handle the remote packet transfers. This
* should never be NULL.
*/
dev = udp_find_raddr_device(conn);
if (dev == NULL)
{
nerr("ERROR: udp_find_raddr_device failed\n");
return -ENETUNREACH;
}
/* Make sure that the device is in the UP state */
if ((dev->d_flags & IFF_UP) == 0)
{
nwarn("WARNING: device is DOWN\n");
return -EHOSTUNREACH;
}
/* If this is not the same device that we used in the last call to
* udp_callback_alloc(), then we need to release and reallocate the old
* callback instance.
*/
if (psock->s_sndcb != NULL && conn->dev != dev)
{
udp_callback_free(conn->dev, conn, psock->s_sndcb);
psock->s_sndcb = NULL;
}
/* Allocate resources to receive a callback from this device if the
* callback is not already in place.
*/
if (psock->s_sndcb == NULL)
{
psock->s_sndcb = udp_callback_alloc(dev, conn);
}
/* Test if the callback has been allocated */
if (psock->s_sndcb == NULL)
{
/* A buffer allocation error occurred */
nerr("ERROR: Failed to allocate callback\n");
return -ENOMEM;
}
conn->dev = dev;
/* Set up the callback in the connection */
psock->s_sndcb->flags = (UDP_POLL | NETDEV_DOWN);
psock->s_sndcb->priv = (FAR void *)psock;
psock->s_sndcb->event = sendto_eventhandler;
/* Notify the device driver of the availability of TX data */
netdev_txnotify_dev(dev);
return OK;
}
/****************************************************************************
* Name: sendto_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
* 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 sendto_eventhandler(FAR struct net_driver_s *dev,
FAR void *pvconn, FAR void *pvpriv,
uint16_t flags)
{
FAR struct udp_conn_s *conn = (FAR struct udp_conn_s *)pvconn;
FAR struct socket *psock = (FAR struct socket *)pvpriv;
ninfo("flags: %04x\n", flags);
/* Check if the network device has gone down */
if ((flags & NETDEV_DOWN) != 0)
{
ninfo("Device down: %04x\n", flags);
/* Free the write buffer at the head of the queue and attempt to setup
* the next transfer.
*/
sendto_writebuffer_release(psock, conn);
return flags;
}
/* Check for a normal polling cycle and if the outgoing packet is
* available. It would not be available if it has been claimed by a send
* event serving a different thread -OR- if the output buffer currently
* contains unprocessed incoming data. In these cases we will just have
* to wait for the next polling cycle.
*
* And, of course, we can do nothing if we have no data in the write
* buffers to send.
*/
if (dev->d_sndlen <= 0 && (flags & UDP_NEWDATA) == 0 &&
(flags & UDP_POLL) != 0 && !sq_empty(&conn->write_q))
{
/* Check if the destination IP address is in the ARP, Neighbor
* table, or routing table. If not, then the send won't actually
* make it out... it will be replaced with an ARP request or
* Neighbor Solicitation.
*/
if (sendto_addrcheck(conn, dev))
{
FAR struct udp_wrbuffer_s *wrb;
size_t sndlen;
/* Peek at the head of the write queue (but don't remove anything
* from the write queue yet). We know from the above test that
* the write_q is not empty.
*/
wrb = (FAR struct udp_wrbuffer_s *)sq_peek(&conn->write_q);
DEBUGASSERT(wrb != NULL);
/* Get the amount of data that we can send in the next packet.
* We will send either the remaining data in the buffer I/O
* buffer chain, or as much as will fit given the MSS and current
* window size.
*/
sndlen = wrb->wb_iob->io_pktlen;
ninfo("wrb=%p sndlen=%u\n", wrb, sndlen);
#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.
*/
sendto_ipselect(dev, conn);
#endif
/* Then set-up to send that amount of data with the offset
* corresponding to the size of the IP-dependent address structure.
*/
devif_iob_send(dev, wrb->wb_iob, sndlen, 0);
/* Free the write buffer at the head of the queue and attempt to
* setup the next transfer.
*/
sendto_writebuffer_release(psock, conn);
/* Only one data can be sent by low level driver at once,
* tell the caller stop polling the other connections.
*/
flags &= ~UDP_POLL;
}
}
#ifdef CONFIG_NET_SOCKOPTS
/* We cannot send the data now. Check for a timeout. */
else if (sendto_timeout(psock, conn))
{
/* Free the write buffer at the head of the queue and attempt to setup
* the next transfer.
*/
sendto_writebuffer_release(psock, conn);
}
#endif /* CONFIG_NET_SOCKOPTS */
/* Continue waiting */
return flags;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: psock_udp_sendto
*
* Description:
* This function implements the UDP-specific logic of the standard
* sendto() socket operation.
*
* Input Parameters:
* psock A pointer to a NuttX-specific, internal socket structure
* buf Data to send
* len Length of data to send
* flags Send flags
* to Address of recipient
* tolen The length of the address structure
*
* NOTE: All input parameters were verified by sendto() before this
* function was called.
*
* Returned Value:
* On success, returns the number of characters sent. On error,
* a negated errno value is returned. See the description in
* net/socket/sendto.c for the list of appropriate return value.
*
****************************************************************************/
ssize_t psock_udp_sendto(FAR struct socket *psock, FAR const void *buf,
size_t len, int flags, FAR const struct sockaddr *to,
socklen_t tolen)
{
FAR struct udp_conn_s *conn;
FAR struct udp_wrbuffer_s *wrb;
int ret = OK;
/* If the UDP socket was previously assigned a remote peer address via
* connect(), then as with connection-mode socket, sendto() may not be
* used with a non-NULL destination address. Normally send() would be
* used with such connected UDP sockets.
*/
if (to != NULL && _SS_ISCONNECTED(psock->s_flags))
{
/* EISCONN - A destination address was specified and the socket is
* already connected.
*/
return -EISCONN;
}
/* Otherwise, if the socket is not connected, then a destination address
* must be provided.
*/
else if (to == NULL && !_SS_ISCONNECTED(psock->s_flags))
{
/* EDESTADDRREQ - The socket is not connection-mode and no peer
* address is set.
*/
return -EDESTADDRREQ;
}
/* Get the underlying the UDP connection structure. */
conn = (FAR struct udp_conn_s *)psock->s_conn;
DEBUGASSERT(conn);
#if defined(CONFIG_NET_ARP_SEND) || defined(CONFIG_NET_ICMPv6_NEIGHBOR)
#ifdef CONFIG_NET_ARP_SEND
/* Assure the the IPv4 destination address maps to a valid MAC address in
* the ARP table.
*/
#ifdef CONFIG_NET_ICMPv6_NEIGHBOR
if (psock->s_domain == PF_INET)
#endif
{
in_addr_t destipaddr;
/* Check if the socket is connection mode */
if (_SS_ISCONNECTED(psock->s_flags))
{
/* Yes.. use the connected remote address (the 'to' address is
* null).
*/
destipaddr = conn->u.ipv4.raddr;
}
else
{
FAR const struct sockaddr_in *into;
/* No.. use the destination address provided by the non-NULL 'to'
* argument.
*/
into = (FAR const struct sockaddr_in *)to;
destipaddr = into->sin_addr.s_addr;
}
/* Make sure that the IP address mapping is in the ARP table */
ret = arp_send(destipaddr);
}
#endif /* CONFIG_NET_ARP_SEND */
#ifdef CONFIG_NET_ICMPv6_NEIGHBOR
/* Assure the the IPv6 destination address maps to a valid MAC address in
* the neighbor table.
*/
#ifdef CONFIG_NET_ARP_SEND
else
#endif
{
FAR const uint16_t *destipaddr;
/* Check if the socket is connection mode */
if (_SS_ISCONNECTED(psock->s_flags))
{
/* Yes.. use the connected remote address (the 'to' address is
* null).
*/
destipaddr = conn->u.ipv6.raddr;
}
else
{
FAR const struct sockaddr_in6 *into;
/* No.. use the destination address provided by the non-NULL 'to'
* argument.
*/
into = (FAR const struct sockaddr_in6 *)to;
destipaddr = into->sin6_addr.s6_addr16;
}
/* Make sure that the IP address mapping is in the Neighbor Table */
ret = icmpv6_neighbor(destipaddr);
}
#endif /* CONFIG_NET_ICMPv6_NEIGHBOR */
/* Did we successfully get the address mapping? */
if (ret < 0)
{
nerr("ERROR: Not reachable\n");
return -ENETUNREACH;
}
#endif /* CONFIG_NET_ARP_SEND || CONFIG_NET_ICMPv6_NEIGHBOR */
/* Dump the incoming buffer */
BUF_DUMP("psock_udp_send", buf, len);
/* Set the socket state to sending */
psock->s_flags = _SS_SETSTATE(psock->s_flags, _SF_SEND);
if (len > 0)
{
/* Allocate a write buffer. Careful, the network will be momentarily
* unlocked here.
*/
net_lock();
wrb = udp_wrbuffer_alloc();
if (wrb == NULL)
{
/* A buffer allocation error occurred */
nerr("ERROR: Failed to allocate write buffer\n");
ret = -ENOMEM;
goto errout_with_lock;
}
/* Initialize the write buffer
*
* Check if the socket is connected
*/
if (_SS_ISCONNECTED(psock->s_flags))
{
/* Yes.. get the connection address from the connection structure */
#ifdef CONFIG_NET_IPv4
#ifdef CONFIG_NET_IPv6
if (conn->domain == PF_INET)
#endif
{
FAR struct sockaddr_in *addr4 =
(FAR struct sockaddr_in *)&wrb->wb_dest;
addr4->sin_family = AF_INET;
addr4->sin_port = conn->rport;
net_ipv4addr_copy(addr4->sin_addr.s_addr, conn->u.ipv4.raddr);
}
#endif /* CONFIG_NET_IPv4 */
#ifdef CONFIG_NET_IPv6
#ifdef CONFIG_NET_IPv4
else
#endif
{
FAR struct sockaddr_in6 *addr6 =
(FAR struct sockaddr_in6 *)&wrb->wb_dest;
addr6->sin6_family = AF_INET6;
addr6->sin6_port = conn->rport;
net_ipv6addr_copy(addr6->sin6_addr.s6_addr, conn->u.ipv6.raddr);
}
#endif /* CONFIG_NET_IPv6 */
}
/* Not connected. Use the provided destination address */
else
{
memcpy(&wrb->wb_dest, to, tolen);
}
#ifdef CONFIG_NET_SOCKOPTS
wrb->wb_start = clock_systimer();
#endif
/* Copy the user data into the write buffer. We cannot wait for
* buffer space if the socket was opened non-blocking.
*/
if (_SS_ISNONBLOCK(psock->s_flags))
{
ret = iob_trycopyin(wrb->wb_iob, (FAR uint8_t *)buf, len, 0, false);
}
else
{
ret = iob_copyin(wrb->wb_iob, (FAR uint8_t *)buf, len, 0, false);
}
if (ret < 0)
{
goto errout_with_wrb;
}
/* Dump I/O buffer chain */
UDP_WBDUMP("I/O buffer chain", wrb, wrb->wb_iob->io_pktlen, 0);
/* sendto_eventhandler() will send data in FIFO order from the
* conn->write_q.
*
* REVISIT: Why FIFO order? Because it is easy. In a real world
* environment where there are multiple network devices this might
* be inefficient because we could be sending data to different
* device out-of-queued-order to optimize performance. Sending
* data to different networks from a single UDP socket is probably
* not a very common use case, however.
*/
sq_addlast(&wrb->wb_node, &conn->write_q);
ninfo("Queued WRB=%p pktlen=%u write_q(%p,%p)\n",
wrb, wrb->wb_iob->io_pktlen,
conn->write_q.head, conn->write_q.tail);
/* Set up for the next packet transfer by setting the connection
* address to the address of the next packet now at the header of the
* write buffer queue.
*/
ret = sendto_next_transfer(psock, conn);
if (ret < 0)
{
(void)sq_remlast(&conn->write_q);
goto errout_with_wrb;
}
net_unlock();
}
/* Set the socket state to idle */
psock->s_flags = _SS_SETSTATE(psock->s_flags, _SF_IDLE);
/* Return the number of bytes that will be sent */
return len;
errout_with_wrb:
udp_wrbuffer_release(wrb);
errout_with_lock:
net_unlock();
return ret;
}
/****************************************************************************
* Name: psock_udp_cansend
*
* Description:
* psock_udp_cansend() returns a value indicating if a write to the socket
* would block. No space in the buffer is actually reserved, so it is
* possible that the write may still block if the buffer is filled by
* another means.
*
* Input Parameters:
* psock An instance of the internal socket structure.
*
* Returned Value:
* OK
* At least one byte of data could be successfully written.
* -EWOULDBLOCK
* There is no room in the output buffer.
* -EBADF
* An invalid descriptor was specified.
*
****************************************************************************/
int psock_udp_cansend(FAR struct socket *psock)
{
/* Verify that we received a valid socket */
if (!psock || psock->s_crefs <= 0)
{
nerr("ERROR: Invalid socket\n");
return -EBADF;
}
/* In order to setup the send, we need to have at least one free write
* buffer head and at least one free IOB to initialize the write buffer
* head.
*
* REVISIT: The send will still block if we are unable to buffer the
* entire user-provided buffer which may be quite large. We will almost
* certainly need to have more than one free IOB, but we don't know how
* many more.
*/
if (udp_wrbuffer_test() < 0 || iob_navail(false) <= 0)
{
return -EWOULDBLOCK;
}
return OK;
}
#endif /* CONFIG_NET && CONFIG_NET_UDP && CONFIG_NET_UDP_WRITE_BUFFERS */
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