diff options
| -rw-r--r-- | ldra.c | 26 |
1 files changed, 17 insertions, 9 deletions
@@ -155,7 +155,7 @@ u_int16_t csum_ipv6udp(struct ip6_hdr *ip6, const u_int16_t *data, size_t datal */ -int newalgo = 0; // does not work... +int newalgo = 1; u_int32_t wrapsum(u_int32_t sum) { sum = ~sum & 0xFFFF; @@ -200,17 +200,17 @@ u_int32_t checksum(unsigned char *buf, unsigned nbytes, u_int32_t sum) { /* calulate a possibly partial checksum */ u_int32_t chksum(u_int8_t *buf, size_t n) { - u_int32_t sum; + u_int32_t sum = 0; int i; - for (i = 0; i < n/2; i += 2) - sum += (u_int16_t)ntohs(*(u_int16_t *)(buf + i)); + for (i = 0; i <(n & ~1U); i += 2) + sum += (u_int16_t)ntohs(*((u_int16_t *)(buf + i))); /* odd number of bytes? */ if (i < n) sum += buf[i] << 8; - return sum; + return (sum); } @@ -621,14 +621,22 @@ Steven McCanne and Van Jacobson of Lawrence Berkeley Laboratory. udp->check = 0; /* reset before calculating new checksum */ if (!newalgo) { /* FIMXE: testing */ - udp->check = wrapsum(checksum((unsigned char *)udp, sizeof(struct udphdr) + datalen, /* udp header + packet data */ + u_int16_t oldchksum, newchksum; + + oldchksum = wrapsum(checksum((unsigned char *)udp, sizeof(struct udphdr) + datalen, /* udp header + packet data */ checksum((unsigned char *)&ip6->ip6_src, 2 * sizeof(ip6->ip6_src), /* src + dst address */ IPPROTO_UDP + (u_int32_t)ntohs(udp->len)))); /* final part of pseudo header */ - - } else { - udp->check = complement(chksum((u_int8_t *)udp, sizeof(struct udphdr) + datalen) + /* udp header + packet data */ + newchksum = complement(chksum((u_int8_t *)udp, sizeof(struct udphdr) + datalen) + /* udp header + packet data */ chksum((u_int8_t *)&ip6->ip6_src, 2 * sizeof(ip6->ip6_src)) + /* src + dst address */ IPPROTO_UDP + (u_int32_t)ntohs(udp->len)); /* final part of pseudo header */ + + fprintf(stderr, "old chksum code: %#06hx, new checksum code: %#06hx\n",oldchksum,newchksum); + udp->check = oldchksum; + + } else { + udp->check = complement(chksum((u_int8_t *)udp, sizeof(struct udphdr) + datalen) + /* udp header + packet data */ + chksum((u_int8_t *)&ip6->ip6_src, 2 * sizeof(ip6->ip6_src)) + /* src + dst address */ + IPPROTO_UDP + (u_int32_t)ntohs(udp->len)); /* final part of pseudo header */ } packetlen = sizeof(struct ethhdr) + VLANTAGZ + sizeof(struct ip6_hdr) + ntohs(udp->len); |