nuttx/net/devif/devif_forward.c

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/****************************************************************************
* net/devif/devif_forward.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 <string.h>
#include <assert.h>
#include <debug.h>
#include <nuttx/mm/iob.h>
#include <nuttx/net/netdev.h>
#include "ipforward/ipforward.h"
#include "devif/devif.h"
#ifdef CONFIG_NET_IPFORWARD
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: devif_forward
*
* Description:
* Called from protocol-specific IP forwarding logic to re-send a packet.
*
* Input Parameters:
* fwd - An initialized instance of the common forwarding structure that
* includes everything needed to perform the forwarding operation.
*
* Returned Value:
* None
*
* Assumptions:
* The network is locked.
*
****************************************************************************/
void devif_forward(FAR struct forward_s *fwd)
{
unsigned int offset;
int ret;
DEBUGASSERT(fwd != NULL && fwd->f_iob != NULL && fwd->f_dev != NULL);
offset = NET_LL_HDRLEN(fwd->f_dev);
/* Copy the IOB chain that contains the L3L3 headers and any data payload */
This commit attempts remove some long standard confusion in naming and some actual problems that result from the naming confusion. The basic problem is the standard MTU does not include the size of the Ethernet header. For clarity, I changed the naming of most things called MTU to PKTSIZE. For example, CONFIG_NET_ETH_MTU is now CONFIG_NET_ETH_PKTSIZE. This makes the user interface a little hostile. People thing of an MTU of 1500 bytes, but the corresponding packet is really 1514 bytes (including the 14 byte Ethernet header). A more friendly solution would configure the MTU (as before), but then derive the packet buffer size by adding the MAC header length. Instead, we define the packet buffer size then derive the MTU. The MTU is not common currency in networking. On the wire, the only real issue is the MSS which is derived from MTU by subtracting the IP header and TCP header sizes (for the case of TCP). Now it is derived for the PKTSIZE by subtracting the IP header, the TCP header, and the MAC header sizes. So we should be all good and without the recurring 14 byte error in MTU's and MSS's. Squashed commit of the following: Trivial update to fix some spacing issues. net/: Rename several macros containing _MTU to _PKTSIZE. net/: Rename CONFIG_NET_SLIP_MTU to CONFIG_NET_SLIP_PKTSIZE and similarly for CONFIG_NET_TUN_MTU. These are not the MTU which does not include the size of the link layer header. These are the full size of the packet buffer memory (minus any GUARD bytes). net/: Rename CONFIG_NET_6LOWPAN_MTU to CONFIG_NET_6LOWPAN_PKTSIZE and similarly for CONFIG_NET_TUN_MTU. These are not the MTU which does not include the size of the link layer header. These are the full size of the packet buffer memory (minus any GUARD bytes). net/: Rename CONFIG_NET_ETH_MTU to CONFIG_NET_ETH_PKTSIZE. This is not the MTU which does not include the size of the link layer header. This is the full size of the packet buffer memory (minus any GUARD bytes). net/: Rename the file d_mtu in the network driver structure to d_pktsize. That value saved there is not the MTU. The packetsize is the memory large enough to hold the maximum packet PLUS the size of the link layer header. The MTU does not include the link layer header.
2018-07-04 22:10:40 +02:00
DEBUGASSERT(offset + fwd->f_iob->io_pktlen <= NETDEV_PKTSIZE(fwd->f_dev));
ret = iob_copyout(&fwd->f_dev->d_buf[offset], fwd->f_iob,
fwd->f_iob->io_pktlen, 0);
DEBUGASSERT(ret == fwd->f_iob->io_pktlen);
fwd->f_dev->d_sndlen = 0;
fwd->f_dev->d_len = fwd->f_iob->io_pktlen;
UNUSED(ret);
}
#endif /* CONFIG_NET_IPFORWARD */