diff options
Diffstat (limited to 'contrib/tcpdump/print-ip.c')
-rw-r--r-- | contrib/tcpdump/print-ip.c | 160 |
1 files changed, 62 insertions, 98 deletions
diff --git a/contrib/tcpdump/print-ip.c b/contrib/tcpdump/print-ip.c index dc9d266..9896233 100644 --- a/contrib/tcpdump/print-ip.c +++ b/contrib/tcpdump/print-ip.c @@ -89,7 +89,7 @@ ip_printroute(register const u_char *cp, u_int length) * This is used for UDP and TCP pseudo-header in the checksum * calculation. */ -u_int32_t +static u_int32_t ip_finddst(const struct ip *ip) { int length; @@ -131,6 +131,39 @@ trunc: return retval; } +/* + * Compute a V4-style checksum by building a pseudoheader. + */ +int +nextproto4_cksum(const struct ip *ip, const u_int8_t *data, + u_int len, u_int next_proto) +{ + struct phdr { + u_int32_t src; + u_int32_t dst; + u_char mbz; + u_char proto; + u_int16_t len; + } ph; + struct cksum_vec vec[2]; + + /* pseudo-header.. */ + ph.len = htons((u_int16_t)len); + ph.mbz = 0; + ph.proto = next_proto; + memcpy(&ph.src, &ip->ip_src.s_addr, sizeof(u_int32_t)); + if (IP_HL(ip) == 5) + memcpy(&ph.dst, &ip->ip_dst.s_addr, sizeof(u_int32_t)); + else + ph.dst = ip_finddst(ip); + + vec[0].ptr = (const u_int8_t *)(void *)&ph; + vec[0].len = sizeof(ph); + vec[1].ptr = data; + vec[1].len = len; + return (in_cksum(vec, 2)); +} + static void ip_printts(register const u_char *cp, u_int length) { @@ -270,92 +303,6 @@ trunc: printf("[|ip]"); } -/* - * compute an IP header checksum. - * don't modifiy the packet. - */ -u_short -in_cksum(const u_short *addr, register u_int len, int csum) -{ - int nleft = len; - const u_short *w = addr; - u_short answer; - int sum = csum; - - /* - * Our algorithm is simple, using a 32 bit accumulator (sum), - * we add sequential 16 bit words to it, and at the end, fold - * back all the carry bits from the top 16 bits into the lower - * 16 bits. - */ - while (nleft > 1) { - sum += *w++; - nleft -= 2; - } - if (nleft == 1) - sum += htons(*(u_char *)w<<8); - - /* - * add back carry outs from top 16 bits to low 16 bits - */ - sum = (sum >> 16) + (sum & 0xffff); /* add hi 16 to low 16 */ - sum += (sum >> 16); /* add carry */ - answer = ~sum; /* truncate to 16 bits */ - return (answer); -} - -/* - * Given the host-byte-order value of the checksum field in a packet - * header, and the network-byte-order computed checksum of the data - * that the checksum covers (including the checksum itself), compute - * what the checksum field *should* have been. - */ -u_int16_t -in_cksum_shouldbe(u_int16_t sum, u_int16_t computed_sum) -{ - u_int32_t shouldbe; - - /* - * The value that should have gone into the checksum field - * is the negative of the value gotten by summing up everything - * *but* the checksum field. - * - * We can compute that by subtracting the value of the checksum - * field from the sum of all the data in the packet, and then - * computing the negative of that value. - * - * "sum" is the value of the checksum field, and "computed_sum" - * is the negative of the sum of all the data in the packets, - * so that's -(-computed_sum - sum), or (sum + computed_sum). - * - * All the arithmetic in question is one's complement, so the - * addition must include an end-around carry; we do this by - * doing the arithmetic in 32 bits (with no sign-extension), - * and then adding the upper 16 bits of the sum, which contain - * the carry, to the lower 16 bits of the sum, and then do it - * again in case *that* sum produced a carry. - * - * As RFC 1071 notes, the checksum can be computed without - * byte-swapping the 16-bit words; summing 16-bit words - * on a big-endian machine gives a big-endian checksum, which - * can be directly stuffed into the big-endian checksum fields - * in protocol headers, and summing words on a little-endian - * machine gives a little-endian checksum, which must be - * byte-swapped before being stuffed into a big-endian checksum - * field. - * - * "computed_sum" is a network-byte-order value, so we must put - * it in host byte order before subtracting it from the - * host-byte-order value from the header; the adjusted checksum - * will be in host byte order, which is what we'll return. - */ - shouldbe = sum; - shouldbe += ntohs(computed_sum); - shouldbe = (shouldbe & 0xFFFF) + (shouldbe >> 16); - shouldbe = (shouldbe & 0xFFFF) + (shouldbe >> 16); - return shouldbe; -} - #define IP_RES 0x8000 static struct tok ip_frag_values[] = { @@ -378,6 +325,7 @@ ip_print_demux(netdissect_options *ndo, struct ip_print_demux_state *ipds) { struct protoent *proto; + struct cksum_vec vec[1]; again: switch (ipds->nh) { @@ -482,7 +430,7 @@ again: case IPPROTO_IPV4: /* DVMRP multicast tunnel (ip-in-ip encapsulation) */ - ip_print(gndo, ipds->cp, ipds->len); + ip_print(ndo, ipds->cp, ipds->len); if (! vflag) { ND_PRINT((ndo, " (ipip-proto-4)")); return; @@ -492,7 +440,7 @@ again: #ifdef INET6 case IPPROTO_IPV6: /* ip6-in-ip encapsulation */ - ip6_print(ipds->cp, ipds->len); + ip6_print(ndo, ipds->cp, ipds->len); break; #endif /*INET6*/ @@ -510,12 +458,25 @@ again: break; case IPPROTO_PIM: - pim_print(ipds->cp, ipds->len, - in_cksum((const u_short*)ipds->cp, ipds->len, 0)); + vec[0].ptr = ipds->cp; + vec[0].len = ipds->len; + pim_print(ipds->cp, ipds->len, in_cksum(vec, 1)); break; case IPPROTO_VRRP: - vrrp_print(ipds->cp, ipds->len, ipds->ip->ip_ttl); + if (packettype == PT_CARP) { + if (vflag) + (void)printf("carp %s > %s: ", + ipaddr_string(&ipds->ip->ip_src), + ipaddr_string(&ipds->ip->ip_dst)); + carp_print(ipds->cp, ipds->len, ipds->ip->ip_ttl); + } else { + if (vflag) + (void)printf("vrrp %s > %s: ", + ipaddr_string(&ipds->ip->ip_src), + ipaddr_string(&ipds->ip->ip_dst)); + vrrp_print(ipds->cp, ipds->len, ipds->ip->ip_ttl); + } break; case IPPROTO_PGM: @@ -563,6 +524,7 @@ ip_print(netdissect_options *ndo, struct ip_print_demux_state *ipds=&ipd; const u_char *ipend; u_int hlen; + struct cksum_vec vec[1]; u_int16_t sum, ip_sum; struct protoent *proto; @@ -575,7 +537,7 @@ ip_print(netdissect_options *ndo, else if (!eflag) printf("IP "); - if ((u_char *)(ipds->ip + 1) > snapend) { + if ((u_char *)(ipds->ip + 1) > ndo->ndo_snapend) { printf("[|ip]"); return; } @@ -613,8 +575,8 @@ ip_print(netdissect_options *ndo, * Cut off the snapshot length to the end of the IP payload. */ ipend = bp + ipds->len; - if (ipend < snapend) - snapend = ipend; + if (ipend < ndo->ndo_snapend) + ndo->ndo_snapend = ipend; ipds->len -= hlen; @@ -660,8 +622,10 @@ ip_print(netdissect_options *ndo, printf(")"); } - if (!Kflag && (u_char *)ipds->ip + hlen <= snapend) { - sum = in_cksum((const u_short *)ipds->ip, hlen, 0); + if (!Kflag && (u_char *)ipds->ip + hlen <= ndo->ndo_snapend) { + vec[0].ptr = (const u_int8_t *)(void *)ipds->ip; + vec[0].len = hlen; + sum = in_cksum(vec, 1); if (sum != 0) { ip_sum = EXTRACT_16BITS(&ipds->ip->ip_sum); (void)printf(", bad cksum %x (->%x)!", ip_sum, @@ -724,7 +688,7 @@ ipN_print(register const u_char *bp, register u_int length) return; #ifdef INET6 case 6: - ip6_print (bp, length); + ip6_print (gndo, bp, length); return; #endif default: |