[Qemu-devel] [4971] Add IP checksumming functions to qemu (Gerd Hoffmann)

[Anthony Liguori]

Revision: 4971
          http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=4971
Author:   aliguori
Date:     2008-07-29 19:40:04 +0000 (Tue, 29 Jul 2008)

Log Message:
-----------
Add IP checksumming functions to qemu (Gerd Hoffmann)

This can be shared between the e1000, virtio-net, and xennet.

Signed-off-by: Gerd Hoffmann <address@hidden>
Signed-off-by: Anthony Liguori <address@hidden>

Modified Paths:
--------------
    trunk/Makefile.target
    trunk/net.h

Added Paths:
-----------
    trunk/net-checksum.c

Modified: trunk/Makefile.target
===================================================================
--- trunk/Makefile.target       2008-07-29 18:11:20 UTC (rev 4970)
+++ trunk/Makefile.target       2008-07-29 19:40:04 UTC (rev 4971)
@@ -472,7 +472,7 @@
 # System emulator target
 ifndef CONFIG_USER_ONLY
 
-OBJS=vl.o osdep.o monitor.o pci.o loader.o isa_mmio.o machine.o
+OBJS=vl.o osdep.o monitor.o pci.o loader.o isa_mmio.o machine.o net-checksum.o
 ifdef CONFIG_WIN32
 OBJS+=block-raw-win32.o
 else

Added: trunk/net-checksum.c
===================================================================
--- trunk/net-checksum.c                                (rev 0)
+++ trunk/net-checksum.c        2008-07-29 19:40:04 UTC (rev 4971)
@@ -0,0 +1,87 @@
+/*
+ *  IP checksumming functions.
+ *  (c) 2008 Gerd Hoffmann <address@hidden>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; under version 2 of the License.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include "hw/hw.h"
+#include "net.h"
+
+#define PROTO_TCP  6
+#define PROTO_UDP 17
+
+uint32_t net_checksum_add(int len, uint8_t *buf)
+{
+    uint32_t sum = 0;
+    int i;
+
+    for (i = 0; i < len; i++) {
+       if (i & 1)
+           sum += (uint32_t)buf[i];
+       else
+           sum += (uint32_t)buf[i] << 8;
+    }
+    return sum;
+}
+
+uint16_t net_checksum_finish(uint32_t sum)
+{
+    while (sum>>16)
+       sum = (sum & 0xFFFF)+(sum >> 16);
+    return ~sum;
+}
+
+uint16_t net_checksum_tcpudp(uint16_t length, uint16_t proto,
+                             uint8_t *addrs, uint8_t *buf)
+{
+    uint32_t sum = 0;
+
+    sum += net_checksum_add(length, buf);         // payload
+    sum += net_checksum_add(8, addrs);            // src + dst address
+    sum += proto + length;                        // protocol & length
+    return net_checksum_finish(sum);
+}
+
+void net_checksum_calculate(uint8_t *data, int length)
+{
+    int hlen, plen, proto, csum_offset;
+    uint16_t csum;
+
+    if ((data[14] & 0xf0) != 0x40)
+       return; /* not IPv4 */
+    hlen  = (data[14] & 0x0f) * 4;
+    plen  = (data[16] << 8 | data[17]) - hlen;
+    proto = data[23];
+
+    switch (proto) {
+    case PROTO_TCP:
+       csum_offset = 16;
+       break;
+    case PROTO_UDP:
+       csum_offset = 6;
+       break;
+    default:
+       return;
+    }
+
+    if (plen < csum_offset+2)
+       return;
+
+    data[14+hlen+csum_offset]   = 0;
+    data[14+hlen+csum_offset+1] = 0;
+    csum = net_checksum_tcpudp(plen, proto, data+14+12, data+14+hlen);
+    data[14+hlen+csum_offset]   = csum >> 8;
+    data[14+hlen+csum_offset+1] = csum & 0xff;
+}

Modified: trunk/net.h
===================================================================
--- trunk/net.h 2008-07-29 18:11:20 UTC (rev 4970)
+++ trunk/net.h 2008-07-29 19:40:04 UTC (rev 4971)
@@ -48,4 +48,11 @@
 extern int nb_nics;
 extern NICInfo nd_table[MAX_NICS];
 
+/* checksumming functions (net-checksum.c) */
+uint32_t net_checksum_add(int len, uint8_t *buf);
+uint16_t net_checksum_finish(uint32_t sum);
+uint16_t net_checksum_tcpudp(uint16_t length, uint16_t proto,
+                             uint8_t *addrs, uint8_t *buf);
+void net_checksum_calculate(uint8_t *data, int length);
+
 #endif