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authorJean-Christophe Dubois <jcd@tribudubois.net>2016-05-30 19:25:46 +0200
committerJason Wang <jasowang@redhat.com>2016-06-02 10:42:30 +0800
commit50dbce6538d10c8ec9c346fdc0ff76906ae48ebe (patch)
treec7d08400bf9e400a2790dc4287396c77a8bd2dbc /net/checksum.c
parent7c375e229456cc06ceb7daf55353d3ad636bdc2f (diff)
net: improve UDP/TCP checksum computation.
* based on Eth, UDP, TCP struct present in eth.h instead of hardcoded indexes and sizes. * based on various macros present in eth.h. Signed-off-by: Jean-Christophe Dubois <jcd@tribudubois.net> Signed-off-by: Jason Wang <jasowang@redhat.com>
Diffstat (limited to 'net/checksum.c')
-rw-r--r--net/checksum.c94
1 files changed, 67 insertions, 27 deletions
diff --git a/net/checksum.c b/net/checksum.c
index 196aaa3459..39ad73f4b4 100644
--- a/net/checksum.c
+++ b/net/checksum.c
@@ -18,9 +18,7 @@
#include "qemu/osdep.h"
#include "qemu-common.h"
#include "net/checksum.h"
-
-#define PROTO_TCP 6
-#define PROTO_UDP 17
+#include "net/eth.h"
uint32_t net_checksum_add_cont(int len, uint8_t *buf, int seq)
{
@@ -57,40 +55,82 @@ uint16_t net_checksum_tcpudp(uint16_t length, uint16_t proto,
void net_checksum_calculate(uint8_t *data, int length)
{
- int hlen, plen, proto, csum_offset;
- uint16_t csum;
+ int ip_len;
+ struct ip_header *ip;
+
+ /*
+ * Note: We cannot assume "data" is aligned, so the all code uses
+ * some macros that take care of possible unaligned access for
+ * struct members (just in case).
+ */
/* Ensure data has complete L2 & L3 headers. */
- if (length < 14 + 20) {
+ if (length < (sizeof(struct eth_header) + sizeof(struct ip_header))) {
return;
}
- 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;
+ ip = (struct ip_header *)(data + sizeof(struct eth_header));
+
+ if (IP_HEADER_VERSION(ip) != IP_HEADER_VERSION_4) {
+ return; /* not IPv4 */
}
- if (plen < csum_offset + 2 || 14 + hlen + plen > length) {
+ ip_len = lduw_be_p(&ip->ip_len);
+
+ /* Last, check that we have enough data for the all IP frame */
+ if (length < ip_len) {
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;
+ ip_len -= IP_HDR_GET_LEN(ip);
+
+ switch (ip->ip_p) {
+ case IP_PROTO_TCP:
+ {
+ uint16_t csum;
+ tcp_header *tcp = (tcp_header *)(ip + 1);
+
+ if (ip_len < sizeof(tcp_header)) {
+ return;
+ }
+
+ /* Set csum to 0 */
+ stw_he_p(&tcp->th_sum, 0);
+
+ csum = net_checksum_tcpudp(ip_len, ip->ip_p,
+ (uint8_t *)&ip->ip_src,
+ (uint8_t *)tcp);
+
+ /* Store computed csum */
+ stw_be_p(&tcp->th_sum, csum);
+
+ break;
+ }
+ case IP_PROTO_UDP:
+ {
+ uint16_t csum;
+ udp_header *udp = (udp_header *)(ip + 1);
+
+ if (ip_len < sizeof(udp_header)) {
+ return;
+ }
+
+ /* Set csum to 0 */
+ stw_he_p(&udp->uh_sum, 0);
+
+ csum = net_checksum_tcpudp(ip_len, ip->ip_p,
+ (uint8_t *)&ip->ip_src,
+ (uint8_t *)udp);
+
+ /* Store computed csum */
+ stw_be_p(&udp->uh_sum, csum);
+
+ break;
+ }
+ default:
+ /* Can't handle any other protocol */
+ break;
+ }
}
uint32_t