projects / qemu.git / blame
| Commit | Line | Data |
|---|---|---|
| 48c64363 AL |
1 | /* |
| 2 | * IP checksumming functions. | |
| 3 | * (c) 2008 Gerd Hoffmann <[email protected]> | |
| 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 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, write to the Free Software | |
| 16 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
| 17 | */ | |
| 18 | ||
| 19 | #include "hw/hw.h" | |
| 20 | #include "net.h" | |
| 21 | ||
| 22 | #define PROTO_TCP 6 | |
| 23 | #define PROTO_UDP 17 | |
| 24 | ||
| 25 | uint32_t net_checksum_add(int len, uint8_t *buf) | |
| 26 | { | |
| 27 | uint32_t sum = 0; | |
| 28 | int i; | |
| 29 | ||
| 30 | for (i = 0; i < len; i++) { | |
| 31 | if (i & 1) | |
| 32 | sum += (uint32_t)buf[i]; | |
| 33 | else | |
| 34 | sum += (uint32_t)buf[i] << 8; | |
| 35 | } | |
| 36 | return sum; | |
| 37 | } | |
| 38 | ||
| 39 | uint16_t net_checksum_finish(uint32_t sum) | |
| 40 | { | |
| 41 | while (sum>>16) | |
| 42 | sum = (sum & 0xFFFF)+(sum >> 16); | |
| 43 | return ~sum; | |
| 44 | } | |
| 45 | ||
| 46 | uint16_t net_checksum_tcpudp(uint16_t length, uint16_t proto, | |
| 47 | uint8_t *addrs, uint8_t *buf) | |
| 48 | { | |
| 49 | uint32_t sum = 0; | |
| 50 | ||
| 51 | sum += net_checksum_add(length, buf); // payload | |
| 52 | sum += net_checksum_add(8, addrs); // src + dst address | |
| 53 | sum += proto + length; // protocol & length | |
| 54 | return net_checksum_finish(sum); | |
| 55 | } | |
| 56 | ||
| 57 | void net_checksum_calculate(uint8_t *data, int length) | |
| 58 | { | |
| 59 | int hlen, plen, proto, csum_offset; | |
| 60 | uint16_t csum; | |
| 61 | ||
| 62 | if ((data[14] & 0xf0) != 0x40) | |
| 63 | return; /* not IPv4 */ | |
| 64 | hlen = (data[14] & 0x0f) * 4; | |
| 65 | plen = (data[16] << 8 | data[17]) - hlen; | |
| 66 | proto = data[23]; | |
| 67 | ||
| 68 | switch (proto) { | |
| 69 | case PROTO_TCP: | |
| 70 | csum_offset = 16; | |
| 71 | break; | |
| 72 | case PROTO_UDP: | |
| 73 | csum_offset = 6; | |
| 74 | break; | |
| 75 | default: | |
| 76 | return; | |
| 77 | } | |
| 78 | ||
| 79 | if (plen < csum_offset+2) | |
| 80 | return; | |
| 81 | ||
| 82 | data[14+hlen+csum_offset] = 0; | |
| 83 | data[14+hlen+csum_offset+1] = 0; | |
| 84 | csum = net_checksum_tcpudp(plen, proto, data+14+12, data+14+hlen); | |
| 85 | data[14+hlen+csum_offset] = csum >> 8; | |
| 86 | data[14+hlen+csum_offset+1] = csum & 0xff; | |
| 87 | } |