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-rw-r--r--qemu/roms/ipxe/src/net/ethernet.c50
1 files changed, 47 insertions, 3 deletions
diff --git a/qemu/roms/ipxe/src/net/ethernet.c b/qemu/roms/ipxe/src/net/ethernet.c
index 03978c2a8..6ddf05344 100644
--- a/qemu/roms/ipxe/src/net/ethernet.c
+++ b/qemu/roms/ipxe/src/net/ethernet.c
@@ -15,9 +15,13 @@
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
+ *
+ * You can also choose to distribute this program under the terms of
+ * the Unmodified Binary Distribution Licence (as given in the file
+ * COPYING.UBDL), provided that you have satisfied its requirements.
*/
-FILE_LICENCE ( GPL2_OR_LATER );
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
#include <stdint.h>
#include <stdlib.h>
@@ -43,6 +47,24 @@ FILE_LICENCE ( GPL2_OR_LATER );
uint8_t eth_broadcast[ETH_ALEN] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
/**
+ * Check if Ethernet packet has an 802.3 LLC header
+ *
+ * @v ethhdr Ethernet header
+ * @ret is_llc Packet has 802.3 LLC header
+ */
+static inline int eth_is_llc_packet ( struct ethhdr *ethhdr ) {
+ uint8_t len_msb;
+
+ /* Check if the protocol field contains a value short enough
+ * to be a frame length. The slightly convoluted form of the
+ * comparison is designed to reduce to a single x86
+ * instruction.
+ */
+ len_msb = *( ( uint8_t * ) &ethhdr->h_protocol );
+ return ( len_msb < 0x06 );
+}
+
+/**
* Add Ethernet link-layer header
*
* @v netdev Network device
@@ -80,9 +102,14 @@ int eth_pull ( struct net_device *netdev __unused, struct io_buffer *iobuf,
const void **ll_dest, const void **ll_source,
uint16_t *net_proto, unsigned int *flags ) {
struct ethhdr *ethhdr = iobuf->data;
+ uint16_t *llc_proto;
- /* Sanity check */
- if ( iob_len ( iobuf ) < sizeof ( *ethhdr ) ) {
+ /* Sanity check. While in theory we could receive a one-byte
+ * packet, this will never happen in practice and performing
+ * the combined length check here avoids the need for an
+ * additional comparison if we detect an LLC frame.
+ */
+ if ( iob_len ( iobuf ) < ( sizeof ( *ethhdr ) + sizeof ( *llc_proto ))){
DBG ( "Ethernet packet too short (%zd bytes)\n",
iob_len ( iobuf ) );
return -EINVAL;
@@ -100,6 +127,17 @@ int eth_pull ( struct net_device *netdev __unused, struct io_buffer *iobuf,
( is_broadcast_ether_addr ( ethhdr->h_dest ) ?
LL_BROADCAST : 0 ) );
+ /* If this is an LLC frame (with a length in place of the
+ * protocol field), then use the next two bytes (which happen
+ * to be the LLC DSAP and SSAP) as the protocol. This allows
+ * for minimal-overhead support for receiving (rare) LLC
+ * frames, without requiring a full LLC protocol layer.
+ */
+ if ( eth_is_llc_packet ( ethhdr ) ) {
+ llc_proto = ( &ethhdr->h_protocol + 1 );
+ *net_proto = *llc_proto;
+ }
+
return 0;
}
@@ -235,5 +273,11 @@ struct net_device * alloc_etherdev ( size_t priv_size ) {
return netdev;
}
+/* Drag in objects via ethernet_protocol */
+REQUIRING_SYMBOL ( ethernet_protocol );
+
+/* Drag in Ethernet configuration */
+REQUIRE_OBJECT ( config_ethernet );
+
/* Drag in Ethernet slow protocols */
REQUIRE_OBJECT ( eth_slow );