X-Git-Url: https://git.tcpdump.org/tcpdump/blobdiff_plain/a91d20cc8491f2afcc04e51474244710481244b9..4c2790a43252b9cac1fe7f6b50b51c3c55d2370a:/print-ip.c diff --git a/print-ip.c b/print-ip.c index f42276dc..494eb295 100644 --- a/print-ip.c +++ b/print-ip.c @@ -87,7 +87,7 @@ 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; @@ -129,6 +129,39 @@ 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) { @@ -268,92 +301,6 @@ 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[] = { @@ -376,6 +323,7 @@ ip_print_demux(netdissect_options *ndo, struct ip_print_demux_state *ipds) { struct protoent *proto; + struct cksum_vec vec[1]; again: switch (ipds->nh) { @@ -402,7 +350,7 @@ again: ipds->nh = enh & 0xff; goto again; } - + case IPPROTO_IPCOMP: { int enh; @@ -422,25 +370,25 @@ again: case IPPROTO_DCCP: dccp_print(ipds->cp, (const u_char *)ipds->ip, ipds->len); break; - + case IPPROTO_TCP: /* pass on the MF bit plus the offset to detect fragments */ tcp_print(ipds->cp, ipds->len, (const u_char *)ipds->ip, ipds->off & (IP_MF|IP_OFFMASK)); break; - + case IPPROTO_UDP: /* pass on the MF bit plus the offset to detect fragments */ udp_print(ipds->cp, ipds->len, (const u_char *)ipds->ip, ipds->off & (IP_MF|IP_OFFMASK)); break; - + case IPPROTO_ICMP: /* pass on the MF bit plus the offset to detect fragments */ icmp_print(ipds->cp, ipds->len, (const u_char *)ipds->ip, ipds->off & (IP_MF|IP_OFFMASK)); break; - + case IPPROTO_PIGP: /* * XXX - the current IANA protocol number assignments @@ -457,11 +405,11 @@ again: */ igrp_print(ipds->cp, ipds->len, (const u_char *)ipds->ip); break; - + case IPPROTO_EIGRP: eigrp_print(ipds->cp, ipds->len); break; - + case IPPROTO_ND: ND_PRINT((ndo, " nd %d", ipds->len)); break; @@ -486,7 +434,7 @@ again: return; } break; - + #ifdef INET6 case IPPROTO_IPV6: /* ip6-in-ip encapsulation */ @@ -508,12 +456,25 @@ 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: @@ -521,7 +482,7 @@ again: break; default: - if ((proto = getprotobynumber(ipds->nh)) != NULL) + if (ndo->ndo_nflag==0 && (proto = getprotobynumber(ipds->nh)) != NULL) ND_PRINT((ndo, " %s", proto->p_name)); else ND_PRINT((ndo, " ip-proto-%d", ipds->nh)); @@ -529,7 +490,7 @@ again: break; } } - + void ip_print_inner(netdissect_options *ndo, const u_char *bp, @@ -561,6 +522,7 @@ 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; @@ -635,7 +597,7 @@ ip_print(netdissect_options *ndo, } if (ipds->ip->ip_ttl >= 1) - (void)printf(", ttl %u", ipds->ip->ip_ttl); + (void)printf(", ttl %u", ipds->ip->ip_ttl); /* * for the firewall guys, print id, offset. @@ -659,7 +621,9 @@ ip_print(netdissect_options *ndo, } if (!Kflag && (u_char *)ipds->ip + hlen <= ndo->ndo_snapend) { - sum = in_cksum((const u_short *)ipds->ip, hlen, 0); + 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, @@ -697,11 +661,11 @@ ip_print(netdissect_options *ndo, if (ipds->off & 0x1fff) { (void)printf("%s > %s:", ipaddr_string(&ipds->ip->ip_src), ipaddr_string(&ipds->ip->ip_dst)); - if ((proto = getprotobynumber(ipds->ip->ip_p)) != NULL) + if (!ndo->ndo_nflag && (proto = getprotobynumber(ipds->ip->ip_p)) != NULL) (void)printf(" %s", proto->p_name); else (void)printf(" ip-proto-%d", ipds->ip->ip_p); - } + } } }