diff options
Diffstat (limited to 'net/checksum.c')
| -rw-r--r-- | net/checksum.c | 208 |
1 files changed, 208 insertions, 0 deletions
diff --git a/net/checksum.c b/net/checksum.c new file mode 100644 index 000000000..68245fd74 --- /dev/null +++ b/net/checksum.c @@ -0,0 +1,208 @@ +/* + * 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 csum_flag) +{ + int mac_hdr_len, ip_len; + struct ip_header *ip; + uint16_t csum; + + /* + * 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 */ + } + + /* Calculate IP checksum */ + if (csum_flag & CSUM_IP) { + stw_he_p(&ip->ip_sum, 0); + csum = net_raw_checksum((uint8_t *)ip, IP_HDR_GET_LEN(ip)); + stw_be_p(&ip->ip_sum, csum); + } + + if (IP4_IS_FRAGMENT(ip)) { + return; /* a fragmented IP packet */ + } + + 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: + { + if (!(csum_flag & CSUM_TCP)) { + return; + } + + 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: + { + if (!(csum_flag & CSUM_UDP)) { + return; + } + + 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; + unsigned int i; + uint32_t res = 0; + + iovec_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; + + iov_off += len; + size -= len; + } + iovec_off += iov[i].iov_len; + } + return res; +} |