Basic TCP/IP appears to be working for small transfers but when
lwip_write is used to send 512 bytes it all goes horribly wrong.
IP_FRAG is set to 0, IP_FRAG_MAX_MTU is set to 1500, TCP_MSS is set to
1460. There is no shortage of RAM in the system so I have set
MEMP_NUM_TCP_SEG, TCP_SND_BUF and TCP_SND_QUEUELEN to 32768.
Attached is a Wireshark capture showing what look like the data being
placed on the link without any transport headers (frame 14).
The link output functions look like this:
/*****************************************************************************
Function Name: ipOutputStatus
Description: Task to monitor the status of outgoing packets
and to get the
status of the transfer and inform lwIP that they have completed
Parameters: IN pEtherC - Pointer to the data
structure
Return value: none
*****************************************************************************/
static
void
ipOutputStatus(PRTEIP pEtherC)
{
int
iEtherC =
pEtherC->iEtherC;
while
(true
)
{
/* Wait for a
transmision to be completed */
uint32_t
uiIndex = eventWait(pEtherC->ppWriteEventList,
ETHERNET_SIMULTANEOUS_WRITES,
true
);
if
(uiIndex >= 0)
{
/* Get a
pointer to the overlapped data structure */
POLD pOlWrite =
&pEtherC->pOlWrite[uiIndex];
/* Free the
buffer */
pbuf_free(pEtherC->ppWriteBufferList[uiIndex]);
/* Mark as
being ready for re-use */
pEtherC->ppWriteBufferList[uiIndex] = NULL;
/* Get the
result of the transfer lwIP does not care about the result */
ioctl(iEtherC, CTL_GET_OVERLAPPED_WRITE_RESULT, pOlWrite);
}
else
{
TRACE((
"ipOutputStatus:
Error\r\n"));
}
}
}
/*****************************************************************************
End of function ipOutputStatus
******************************************************************************/
/*****************************************************************************
Function Name: ipOutput
Description: This function is called by the ARP module when
it wants
to send a packet on the interface. This function outputs
the pbuf as-is on the link medium.
Parameters: IN pIpNetIf - Pointer to the network
interface
IN pPacket - Pointer to the lwIP pbuf structure
Return value: ERR_OK
*****************************************************************************/
static
err_t
ipOutput(
struct netif *pIpNetIf,
struct
pbuf *pPacket)
{
PRTEIP pEtherC =
(PRTEIP)pIpNetIf->state;
int
iEtherC =
pEtherC->iEtherC;
while
(pPacket)
{
int
iIndex =
ipGetOlWrite(pEtherC);
uint8_t *pbyPacket =
pPacket->payload;
uint32_t uiLength =
(uint32_t)pPacket->len;
POLD
pOlWrite = &pEtherC->pOlWrite[iIndex];
/* Keep a
pointer to this buffer so the output status task can free
it when the
transfer has completed */
pEtherC->ppWriteBufferList[iIndex] = pPacket;
/* Add a
reference to this packet so it is kept until it is
freed when
the completion event is set by the driver. This
wakes the
ipOutputStatus task which frees it */
pbuf_ref(pPacket);
/* Set the
overlapped event */
ioctl(iEtherC,
CTL_SET_OVERLAPPED_WRITE_EVENT, pOlWrite);
/* Write the
packet of data */
write(iEtherC, pbyPacket,
uiLength);
/* Advance to
the next packet */
pPacket =
pPacket->next;
/* With
IP_FRAG set to 0 this should be NULL? */
if
(pPacket)
{
TRACE((
"IpFrag\r\n"));
}
}
return
ERR_OK;
}
/*****************************************************************************
End of function ipOutput
******************************************************************************/
It is like it won't send a TCP packet bigger than 566 bytes, but I
can send UDP packets up to the MTU (1460 bytes of data). I am not
expecting to see the IpFrag debug print statement but I do. Does any one
know what configuration parameter I have got wrong?
TcpProblem2.pcap