diff options
| -rw-r--r-- | net/checksum.c | 94 |
1 files changed, 67 insertions, 27 deletions
diff --git a/net/checksum.c b/net/checksum.c index 196aaa3459..39ad73f4b4 100644 --- a/net/checksum.c +++ b/net/checksum.c @@ -18,9 +18,7 @@ #include "qemu/osdep.h" #include "qemu-common.h" #include "net/checksum.h" - -#define PROTO_TCP 6 -#define PROTO_UDP 17 +#include "net/eth.h" uint32_t net_checksum_add_cont(int len, uint8_t *buf, int seq) { @@ -57,40 +55,82 @@ uint16_t net_checksum_tcpudp(uint16_t length, uint16_t proto, void net_checksum_calculate(uint8_t *data, int length) { - int hlen, plen, proto, csum_offset; - uint16_t csum; + int 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 data has complete L2 & L3 headers. */ - if (length < 14 + 20) { + if (length < (sizeof(struct eth_header) + sizeof(struct ip_header))) { return; } - if ((data[14] & 0xf0) != 0x40) - return; /* not IPv4 */ - hlen = (data[14] & 0x0f) * 4; - plen = (data[16] << 8 | data[17]) - hlen; - proto = data[23]; - - switch (proto) { - case PROTO_TCP: - csum_offset = 16; - break; - case PROTO_UDP: - csum_offset = 6; - break; - default: - return; + ip = (struct ip_header *)(data + sizeof(struct eth_header)); + + if (IP_HEADER_VERSION(ip) != IP_HEADER_VERSION_4) { + return; /* not IPv4 */ } - if (plen < csum_offset + 2 || 14 + hlen + plen > length) { + 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; } - data[14+hlen+csum_offset] = 0; - data[14+hlen+csum_offset+1] = 0; - csum = net_checksum_tcpudp(plen, proto, data+14+12, data+14+hlen); - data[14+hlen+csum_offset] = csum >> 8; - data[14+hlen+csum_offset+1] = csum & 0xff; + 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 |