| /* |
| * 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/osdep.h" |
| #include "net/checksum.h" |
| #include "net/eth.h" |
| |
| uint32_t net_checksum_add_cont(int len, uint8_t *buf, int seq) |
| { |
| uint32_t sum1 = 0, sum2 = 0; |
| int i; |
| |
| for (i = 0; i < len - 1; i += 2) { |
| sum1 += (uint32_t)buf[i]; |
| sum2 += (uint32_t)buf[i + 1]; |
| } |
| if (i < len) { |
| sum1 += (uint32_t)buf[i]; |
| } |
| |
| if (seq & 1) { |
| return sum1 + (sum2 << 8); |
| } else { |
| return sum2 + (sum1 << 8); |
| } |
| } |
| |
| 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 mac_hdr_len, 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 we have at least an Eth header */ |
| if (length < sizeof(struct eth_header)) { |
| return; |
| } |
| |
| /* Handle the optionnal VLAN headers */ |
| switch (lduw_be_p(&PKT_GET_ETH_HDR(data)->h_proto)) { |
| case ETH_P_VLAN: |
| mac_hdr_len = sizeof(struct eth_header) + |
| sizeof(struct vlan_header); |
| break; |
| case ETH_P_DVLAN: |
| if (lduw_be_p(&PKT_GET_VLAN_HDR(data)->h_proto) == ETH_P_VLAN) { |
| mac_hdr_len = sizeof(struct eth_header) + |
| 2 * sizeof(struct vlan_header); |
| } else { |
| mac_hdr_len = sizeof(struct eth_header) + |
| sizeof(struct vlan_header); |
| } |
| break; |
| default: |
| mac_hdr_len = sizeof(struct eth_header); |
| break; |
| } |
| |
| length -= mac_hdr_len; |
| |
| /* Now check we have an IP header (with an optionnal VLAN header) */ |
| if (length < sizeof(struct ip_header)) { |
| return; |
| } |
| |
| ip = (struct ip_header *)(data + mac_hdr_len); |
| |
| if (IP_HEADER_VERSION(ip) != IP_HEADER_VERSION_4) { |
| return; /* not IPv4 */ |
| } |
| |
| 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; |
| } |
| |
| 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 |
| net_checksum_add_iov(const struct iovec *iov, const unsigned int iov_cnt, |
| uint32_t iov_off, uint32_t size, uint32_t csum_offset) |
| { |
| size_t iovec_off, buf_off; |
| unsigned int i; |
| uint32_t res = 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, csum_offset); |
| csum_offset += len; |
| |
| buf_off += len; |
| iov_off += len; |
| size -= len; |
| } |
| iovec_off += iov[i].iov_len; |
| } |
| return res; |
| } |