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![Michael Tokarev](/assets/img/avatar_default.png)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru> Reviewed-by: Eric Blake <eblake@redhat.com>
209 lines
5.4 KiB
C
209 lines
5.4 KiB
C
/*
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* IP checksumming functions.
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* (c) 2008 Gerd Hoffmann <kraxel@redhat.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; under version 2 or later of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <http://www.gnu.org/licenses/>.
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*/
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#include "qemu/osdep.h"
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#include "net/checksum.h"
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#include "net/eth.h"
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uint32_t net_checksum_add_cont(int len, uint8_t *buf, int seq)
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{
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uint32_t sum1 = 0, sum2 = 0;
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int i;
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for (i = 0; i < len - 1; i += 2) {
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sum1 += (uint32_t)buf[i];
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sum2 += (uint32_t)buf[i + 1];
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}
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if (i < len) {
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sum1 += (uint32_t)buf[i];
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}
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if (seq & 1) {
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return sum1 + (sum2 << 8);
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} else {
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return sum2 + (sum1 << 8);
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}
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}
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uint16_t net_checksum_finish(uint32_t sum)
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{
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while (sum>>16)
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sum = (sum & 0xFFFF)+(sum >> 16);
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return ~sum;
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}
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uint16_t net_checksum_tcpudp(uint16_t length, uint16_t proto,
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uint8_t *addrs, uint8_t *buf)
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{
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uint32_t sum = 0;
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sum += net_checksum_add(length, buf); // payload
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sum += net_checksum_add(8, addrs); // src + dst address
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sum += proto + length; // protocol & length
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return net_checksum_finish(sum);
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}
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void net_checksum_calculate(uint8_t *data, int length, int csum_flag)
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{
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int mac_hdr_len, ip_len;
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struct ip_header *ip;
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uint16_t csum;
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/*
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* Note: We cannot assume "data" is aligned, so the all code uses
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* some macros that take care of possible unaligned access for
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* struct members (just in case).
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*/
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/* Ensure we have at least an Eth header */
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if (length < sizeof(struct eth_header)) {
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return;
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}
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/* Handle the optional VLAN headers */
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switch (lduw_be_p(&PKT_GET_ETH_HDR(data)->h_proto)) {
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case ETH_P_VLAN:
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mac_hdr_len = sizeof(struct eth_header) +
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sizeof(struct vlan_header);
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break;
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case ETH_P_DVLAN:
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if (lduw_be_p(&PKT_GET_VLAN_HDR(data)->h_proto) == ETH_P_VLAN) {
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mac_hdr_len = sizeof(struct eth_header) +
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2 * sizeof(struct vlan_header);
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} else {
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mac_hdr_len = sizeof(struct eth_header) +
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sizeof(struct vlan_header);
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}
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break;
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default:
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mac_hdr_len = sizeof(struct eth_header);
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break;
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}
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length -= mac_hdr_len;
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/* Now check we have an IP header (with an optional VLAN header) */
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if (length < sizeof(struct ip_header)) {
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return;
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}
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ip = (struct ip_header *)(data + mac_hdr_len);
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if (IP_HEADER_VERSION(ip) != IP_HEADER_VERSION_4) {
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return; /* not IPv4 */
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}
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/* Calculate IP checksum */
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if (csum_flag & CSUM_IP) {
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stw_he_p(&ip->ip_sum, 0);
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csum = net_raw_checksum((uint8_t *)ip, IP_HDR_GET_LEN(ip));
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stw_be_p(&ip->ip_sum, csum);
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}
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if (IP4_IS_FRAGMENT(ip)) {
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return; /* a fragmented IP packet */
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}
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ip_len = lduw_be_p(&ip->ip_len);
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/* Last, check that we have enough data for the all IP frame */
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if (length < ip_len) {
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return;
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}
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ip_len -= IP_HDR_GET_LEN(ip);
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switch (ip->ip_p) {
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case IP_PROTO_TCP:
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{
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if (!(csum_flag & CSUM_TCP)) {
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return;
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}
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tcp_header *tcp = (tcp_header *)(ip + 1);
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if (ip_len < sizeof(tcp_header)) {
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return;
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}
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/* Set csum to 0 */
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stw_he_p(&tcp->th_sum, 0);
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csum = net_checksum_tcpudp(ip_len, ip->ip_p,
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(uint8_t *)&ip->ip_src,
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(uint8_t *)tcp);
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/* Store computed csum */
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stw_be_p(&tcp->th_sum, csum);
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break;
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}
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case IP_PROTO_UDP:
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{
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if (!(csum_flag & CSUM_UDP)) {
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return;
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}
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udp_header *udp = (udp_header *)(ip + 1);
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if (ip_len < sizeof(udp_header)) {
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return;
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}
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/* Set csum to 0 */
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stw_he_p(&udp->uh_sum, 0);
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csum = net_checksum_tcpudp(ip_len, ip->ip_p,
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(uint8_t *)&ip->ip_src,
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(uint8_t *)udp);
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/* Store computed csum */
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stw_be_p(&udp->uh_sum, csum);
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break;
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}
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default:
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/* Can't handle any other protocol */
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break;
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}
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}
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uint32_t
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net_checksum_add_iov(const struct iovec *iov, const unsigned int iov_cnt,
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uint32_t iov_off, uint32_t size, uint32_t csum_offset)
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{
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size_t iovec_off;
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unsigned int i;
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uint32_t res = 0;
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iovec_off = 0;
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for (i = 0; i < iov_cnt && size; i++) {
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if (iov_off < (iovec_off + iov[i].iov_len)) {
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size_t len = MIN((iovec_off + iov[i].iov_len) - iov_off , size);
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void *chunk_buf = iov[i].iov_base + (iov_off - iovec_off);
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res += net_checksum_add_cont(len, chunk_buf, csum_offset);
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csum_offset += len;
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iov_off += len;
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size -= len;
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}
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iovec_off += iov[i].iov_len;
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}
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return res;
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}
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