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-rw-r--r--qemu/net/checksum.c115
1 files changed, 115 insertions, 0 deletions
diff --git a/qemu/net/checksum.c b/qemu/net/checksum.c
new file mode 100644
index 000000000..14c08550e
--- /dev/null
+++ b/qemu/net/checksum.c
@@ -0,0 +1,115 @@
+/*
+ * IP checksumming functions.
+ * (c) 2008 Gerd Hoffmann <kraxel@redhat.com>
+ *
+ * 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 or later 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "qemu-common.h"
+#include "net/checksum.h"
+
+#define PROTO_TCP 6
+#define PROTO_UDP 17
+
+uint32_t net_checksum_add_cont(int len, uint8_t *buf, int seq)
+{
+ uint32_t sum = 0;
+ int i;
+
+ for (i = seq; i < seq + len; i++) {
+ if (i & 1) {
+ sum += (uint32_t)buf[i - seq];
+ } else {
+ sum += (uint32_t)buf[i - seq] << 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;
+}
+
+uint32_t
+net_checksum_add_iov(const struct iovec *iov, const unsigned int iov_cnt,
+ uint32_t iov_off, uint32_t size)
+{
+ size_t iovec_off, buf_off;
+ unsigned int i;
+ uint32_t res = 0;
+ uint32_t seq = 0;
+
+ iovec_off = 0;
+ buf_off = 0;
+ for (i = 0; i < iov_cnt && size; i++) {
+ if (iov_off < (iovec_off + iov[i].iov_len)) {
+ size_t len = MIN((iovec_off + iov[i].iov_len) - iov_off , size);
+ void *chunk_buf = iov[i].iov_base + (iov_off - iovec_off);
+
+ res += net_checksum_add_cont(len, chunk_buf, seq);
+ seq += len;
+
+ buf_off += len;
+ iov_off += len;
+ size -= len;
+ }
+ iovec_off += iov[i].iov_len;
+ }
+ return res;
+}