| 1 | /* |
| 2 | * IP checksumming functions. |
| 3 | * (c) 2008 Gerd Hoffmann <kraxel@redhat.com> |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or modify |
| 6 | * it under the terms of the GNU General Public License as published by |
| 7 | * the Free Software Foundation; under version 2 or later of the License. |
| 8 | * |
| 9 | * This program is distributed in the hope that it will be useful, |
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | * GNU General Public License for more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU General Public License |
| 15 | * along with this program; if not, see <http://www.gnu.org/licenses/>. |
| 16 | */ |
| 17 | |
| 18 | #include "qemu/osdep.h" |
| 19 | #include "net/checksum.h" |
| 20 | #include "net/eth.h" |
| 21 | |
| 22 | uint32_t net_checksum_add_cont(int len, uint8_t *buf, int seq) |
| 23 | { |
| 24 | uint32_t sum1 = 0, sum2 = 0; |
| 25 | int i; |
| 26 | |
| 27 | for (i = 0; i < len - 1; i += 2) { |
| 28 | sum1 += (uint32_t)buf[i]; |
| 29 | sum2 += (uint32_t)buf[i + 1]; |
| 30 | } |
| 31 | if (i < len) { |
| 32 | sum1 += (uint32_t)buf[i]; |
| 33 | } |
| 34 | |
| 35 | if (seq & 1) { |
| 36 | return sum1 + (sum2 << 8); |
| 37 | } else { |
| 38 | return sum2 + (sum1 << 8); |
| 39 | } |
| 40 | } |
| 41 | |
| 42 | uint16_t net_checksum_finish(uint32_t sum) |
| 43 | { |
| 44 | while (sum>>16) |
| 45 | sum = (sum & 0xFFFF)+(sum >> 16); |
| 46 | return ~sum; |
| 47 | } |
| 48 | |
| 49 | uint16_t net_checksum_tcpudp(uint16_t length, uint16_t proto, |
| 50 | uint8_t *addrs, uint8_t *buf) |
| 51 | { |
| 52 | uint32_t sum = 0; |
| 53 | |
| 54 | sum += net_checksum_add(length, buf); // payload |
| 55 | sum += net_checksum_add(8, addrs); // src + dst address |
| 56 | sum += proto + length; // protocol & length |
| 57 | return net_checksum_finish(sum); |
| 58 | } |
| 59 | |
| 60 | void net_checksum_calculate(void *data, int length, int csum_flag) |
| 61 | { |
| 62 | int mac_hdr_len, ip_len; |
| 63 | struct ip_header *ip; |
| 64 | uint16_t csum; |
| 65 | |
| 66 | /* |
| 67 | * Note: We cannot assume "data" is aligned, so the all code uses |
| 68 | * some macros that take care of possible unaligned access for |
| 69 | * struct members (just in case). |
| 70 | */ |
| 71 | |
| 72 | /* Ensure we have at least an Eth header */ |
| 73 | if (length < sizeof(struct eth_header)) { |
| 74 | return; |
| 75 | } |
| 76 | |
| 77 | /* Handle the optional VLAN headers */ |
| 78 | switch (lduw_be_p(&PKT_GET_ETH_HDR(data)->h_proto)) { |
| 79 | case ETH_P_VLAN: |
| 80 | mac_hdr_len = sizeof(struct eth_header) + |
| 81 | sizeof(struct vlan_header); |
| 82 | break; |
| 83 | case ETH_P_DVLAN: |
| 84 | if (lduw_be_p(&PKT_GET_VLAN_HDR(data)->h_proto) == ETH_P_VLAN) { |
| 85 | mac_hdr_len = sizeof(struct eth_header) + |
| 86 | 2 * sizeof(struct vlan_header); |
| 87 | } else { |
| 88 | mac_hdr_len = sizeof(struct eth_header) + |
| 89 | sizeof(struct vlan_header); |
| 90 | } |
| 91 | break; |
| 92 | default: |
| 93 | mac_hdr_len = sizeof(struct eth_header); |
| 94 | break; |
| 95 | } |
| 96 | |
| 97 | length -= mac_hdr_len; |
| 98 | |
| 99 | /* Now check we have an IP header (with an optional VLAN header) */ |
| 100 | if (length < sizeof(struct ip_header)) { |
| 101 | return; |
| 102 | } |
| 103 | |
| 104 | ip = (struct ip_header *)((uint8_t *)data + mac_hdr_len); |
| 105 | |
| 106 | if (IP_HEADER_VERSION(ip) != IP_HEADER_VERSION_4) { |
| 107 | return; /* not IPv4 */ |
| 108 | } |
| 109 | |
| 110 | /* Calculate IP checksum */ |
| 111 | if (csum_flag & CSUM_IP) { |
| 112 | stw_he_p(&ip->ip_sum, 0); |
| 113 | csum = net_raw_checksum((uint8_t *)ip, IP_HDR_GET_LEN(ip)); |
| 114 | stw_be_p(&ip->ip_sum, csum); |
| 115 | } |
| 116 | |
| 117 | if (IP4_IS_FRAGMENT(ip)) { |
| 118 | return; /* a fragmented IP packet */ |
| 119 | } |
| 120 | |
| 121 | ip_len = lduw_be_p(&ip->ip_len); |
| 122 | |
| 123 | /* Last, check that we have enough data for the all IP frame */ |
| 124 | if (length < ip_len) { |
| 125 | return; |
| 126 | } |
| 127 | |
| 128 | ip_len -= IP_HDR_GET_LEN(ip); |
| 129 | |
| 130 | switch (ip->ip_p) { |
| 131 | case IP_PROTO_TCP: |
| 132 | { |
| 133 | if (!(csum_flag & CSUM_TCP)) { |
| 134 | return; |
| 135 | } |
| 136 | |
| 137 | tcp_header *tcp = (tcp_header *)(ip + 1); |
| 138 | |
| 139 | if (ip_len < sizeof(tcp_header)) { |
| 140 | return; |
| 141 | } |
| 142 | |
| 143 | /* Set csum to 0 */ |
| 144 | stw_he_p(&tcp->th_sum, 0); |
| 145 | |
| 146 | csum = net_checksum_tcpudp(ip_len, ip->ip_p, |
| 147 | (uint8_t *)&ip->ip_src, |
| 148 | (uint8_t *)tcp); |
| 149 | |
| 150 | /* Store computed csum */ |
| 151 | stw_be_p(&tcp->th_sum, csum); |
| 152 | |
| 153 | break; |
| 154 | } |
| 155 | case IP_PROTO_UDP: |
| 156 | { |
| 157 | if (!(csum_flag & CSUM_UDP)) { |
| 158 | return; |
| 159 | } |
| 160 | |
| 161 | udp_header *udp = (udp_header *)(ip + 1); |
| 162 | |
| 163 | if (ip_len < sizeof(udp_header)) { |
| 164 | return; |
| 165 | } |
| 166 | |
| 167 | /* Set csum to 0 */ |
| 168 | stw_he_p(&udp->uh_sum, 0); |
| 169 | |
| 170 | csum = net_checksum_tcpudp(ip_len, ip->ip_p, |
| 171 | (uint8_t *)&ip->ip_src, |
| 172 | (uint8_t *)udp); |
| 173 | |
| 174 | /* Store computed csum */ |
| 175 | stw_be_p(&udp->uh_sum, csum); |
| 176 | |
| 177 | break; |
| 178 | } |
| 179 | default: |
| 180 | /* Can't handle any other protocol */ |
| 181 | break; |
| 182 | } |
| 183 | } |
| 184 | |
| 185 | uint32_t |
| 186 | net_checksum_add_iov(const struct iovec *iov, const unsigned int iov_cnt, |
| 187 | uint32_t iov_off, uint32_t size, uint32_t csum_offset) |
| 188 | { |
| 189 | size_t iovec_off; |
| 190 | unsigned int i; |
| 191 | uint32_t res = 0; |
| 192 | |
| 193 | iovec_off = 0; |
| 194 | for (i = 0; i < iov_cnt && size; i++) { |
| 195 | if (iov_off < (iovec_off + iov[i].iov_len)) { |
| 196 | size_t len = MIN((iovec_off + iov[i].iov_len) - iov_off , size); |
| 197 | void *chunk_buf = iov[i].iov_base + (iov_off - iovec_off); |
| 198 | |
| 199 | res += net_checksum_add_cont(len, chunk_buf, csum_offset); |
| 200 | csum_offset += len; |
| 201 | |
| 202 | iov_off += len; |
| 203 | size -= len; |
| 204 | } |
| 205 | iovec_off += iov[i].iov_len; |
| 206 | } |
| 207 | return res; |
| 208 | } |