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[netdevice] Provide a test mechanism for discarding packets at random 

Setting NETDEV_DISCARD_RATE to a non-zero value will cause one in
every NETDEV_DISCARD_RATE packets to be discarded at random on both
the transmit and receive datapaths, allowing the robustness of
upper-layer network protocols to be tested even in simulation
environments that provide wholly reliable packet transmission.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
pull/1/head
Michael Brown 2010-07-20 20:52:08 +01:00
parent e4419ff97c
commit 9f2e76ea61
2 changed files with 20 additions and 1 deletions
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1
src/config/general.h
View File

@ -134,6 +134,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
* *
*/ */
#define NETDEV_DISCARD_RATE 0 /* Drop every N packets (0=>no drop) */
#undef BUILD_SERIAL /* Include an automatic build serial #undef BUILD_SERIAL /* Include an automatic build serial
* number. Add "bs" to the list of * number. Add "bs" to the list of
* make targets. For example: * make targets. For example:

20
src/net/netdevice.c
View File

@ -24,6 +24,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
#include <byteswap.h> #include <byteswap.h>
#include <string.h> #include <string.h>
#include <errno.h> #include <errno.h>
#include <config/general.h>
#include <ipxe/if_ether.h> #include <ipxe/if_ether.h>
#include <ipxe/iobuf.h> #include <ipxe/iobuf.h>
#include <ipxe/tables.h> #include <ipxe/tables.h>
@ -126,13 +127,23 @@ int netdev_tx ( struct net_device *netdev, struct io_buffer *iobuf ) {
DBGC ( netdev, "NETDEV %p transmitting %p (%p+%zx)\n", DBGC ( netdev, "NETDEV %p transmitting %p (%p+%zx)\n",
netdev, iobuf, iobuf->data, iob_len ( iobuf ) ); netdev, iobuf, iobuf->data, iob_len ( iobuf ) );
/* Enqueue packet */
list_add_tail ( &iobuf->list, &netdev->tx_queue ); list_add_tail ( &iobuf->list, &netdev->tx_queue );
/* Avoid calling transmit() on unopened network devices */
if ( ! netdev_is_open ( netdev ) ) { if ( ! netdev_is_open ( netdev ) ) {
rc = -ENETUNREACH; rc = -ENETUNREACH;
goto err; goto err;
} }
/* Discard packet (for test purposes) if applicable */
if ( ( NETDEV_DISCARD_RATE > 0 ) &&
( ( random() % NETDEV_DISCARD_RATE ) == 0 ) ) {
rc = -EAGAIN;
goto err;
}
/* Transmit packet */
if ( ( rc = netdev->op->transmit ( netdev, iobuf ) ) != 0 ) if ( ( rc = netdev->op->transmit ( netdev, iobuf ) ) != 0 )
goto err; goto err;
@ -218,6 +229,13 @@ void netdev_rx ( struct net_device *netdev, struct io_buffer *iobuf ) {
DBGC ( netdev, "NETDEV %p received %p (%p+%zx)\n", DBGC ( netdev, "NETDEV %p received %p (%p+%zx)\n",
netdev, iobuf, iobuf->data, iob_len ( iobuf ) ); netdev, iobuf, iobuf->data, iob_len ( iobuf ) );
/* Discard packet (for test purposes) if applicable */
if ( ( NETDEV_DISCARD_RATE > 0 ) &&
( ( random() % NETDEV_DISCARD_RATE ) == 0 ) ) {
netdev_rx_err ( netdev, iobuf, -EAGAIN );
return;
}
/* Enqueue packet */ /* Enqueue packet */
list_add_tail ( &iobuf->list, &netdev->rx_queue ); list_add_tail ( &iobuf->list, &netdev->rx_queue );