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[ncm] Reserve headroom in received packets 

Some protocols (such as ARP) may modify the received packet and re-use
the same I/O buffer for transmission of a reply.  To allow this,
reserve sufficient headroom at the start of each received packet
buffer for our transmit datapath headers.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown 2015-02-06 15:46:43 +00:00
parent 95bc563f0c
commit 2e72d100af
1 changed files with 11 additions and 1 deletions
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12
src/drivers/net/ncm.c
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@ -390,6 +390,7 @@ static void ncm_in_complete ( struct usb_endpoint *ep, struct io_buffer *iobuf,
size_t ndp_len;
size_t pkt_offset;
size_t pkt_len;
size_t headroom;
size_t len;
/* Profile overall bulk IN completion */
@ -460,13 +461,22 @@ static void ncm_in_complete ( struct usb_endpoint *ep, struct io_buffer *iobuf,
* while the device is running. We therefore copy the
* data to a new I/O buffer even if this is the only
* (or last) packet within the buffer.
*
* We reserve enough space at the start of each buffer
* to allow for our own transmission header, to
* support protocols such as ARP which may modify the
* received packet and reuse the same I/O buffer for
* transmission.
*/
pkt = alloc_iob ( pkt_len );
headroom = ( sizeof ( struct ncm_ntb_header ) +
ncm->out.padding );
pkt = alloc_iob ( headroom + pkt_len );
if ( ! pkt ) {
/* Record error and continue */
netdev_rx_err ( netdev, NULL, -ENOMEM );
continue;
}
iob_reserve ( pkt, headroom );
memcpy ( iob_put ( pkt, pkt_len ),
( iobuf->data + pkt_offset ), pkt_len );