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Networking: When upd_input() cannot process a packet, it returns ERROR so that network drivers may try calling ipv4_input() later. In this case, it must also set d_len to zero. Otherwise, all network drivers will assume tht there is also an outgoing packet. This results in a gratuitous ARP.

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This commit is contained in:
Gregory Nutt 2017-07-17 06:50:39 -06:00
parent 1db918d947
commit d9a2a3c3f1
1 changed files with 19 additions and 6 deletions
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25
net/udp/udp_input.c
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@ -72,9 +72,11 @@
* iplen - Length of the IP and UDP headers
*
* Return:
* OK The packet has been processed and can be deleted
* ERROR Hold the packet and try again later. There is a listening socket
* but no receive in place to catch the packet yet.
* OK The packet has been processed and can be deleted
* ERROR Hold the packet and try again later. There is a listening socket
* but no receive in place to catch the packet yet. The device's
* d_len will be set to zero in this case as there is no outgoing
* data.
*
* Assumptions:
* Called from the interrupt level or with interrupts disabled.
@ -185,16 +187,27 @@ static int udp_input(FAR struct net_driver_s *dev, unsigned int iplen)
flags = udp_callback(dev, conn, UDP_NEWDATA);
/* If the operation was successful, the UDP_NEWDATA flag is removed
* and thus the packet can be deleted (OK will be returned).
/* If the operation was successful and the UDP data was "consumed,"
* then the UDP_NEWDATA flag will be cleared by logic in
* udp_callback(). The packet memory can then be freed by the
* network driver. OK will be returned to the network driver to
* indicate this case.
*
* "Consumed" here means that either the received data was (1)
* accepted by a socket waiting for data on the port or was (2)
* buffered in the UDP socket's read-ahead buffer.
*/
if ((flags & UDP_NEWDATA) != 0)
{
/* No.. the packet was not processed now. Return ERROR so
* that the driver may retry again later.
* that the driver may retry again later. We still need to
* set d_len to zero so that the driver is aware that there
* is nothing to be sent.
*/
nwarn("WARNING: Packet not processed\n");
dev->d_len = 0;
ret = ERROR;
}