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49d423e23f
tcpdump/print-ip.c
guy 45aea439a6 Add some bounds checking to the IP options code, and clean up the 
options output a bit.
2006-02-19 05:00:19 +00:00

740 lines
18 KiB
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/*
* Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that: (1) source code distributions
* retain the above copyright notice and this paragraph in its entirety, (2)
* distributions including binary code include the above copyright notice and
* this paragraph in its entirety in the documentation or other materials
* provided with the distribution, and (3) all advertising materials mentioning
* features or use of this software display the following acknowledgement:
* ``This product includes software developed by the University of California,
* Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
* the University nor the names of its contributors may be used to endorse
* or promote products derived from this software without specific prior
* written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
#ifndef lint
static const char rcsid[] _U_ =
"@(#) $Header: /tcpdump/master/tcpdump/print-ip.c,v 1.155 2006-02-19 05:00:19 guy Exp $ (LBL)";
#endif
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <tcpdump-stdinc.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "addrtoname.h"
#include "interface.h"
#include "extract.h" /* must come after interface.h */
#include "ip.h"
#include "ipproto.h"
struct tok ip_option_values[] = {
{ IPOPT_EOL, "EOL" },
{ IPOPT_NOP, "NOP" },
{ IPOPT_TS, "timestamp" },
{ IPOPT_SECURITY, "security" },
{ IPOPT_RR, "RR" },
{ IPOPT_SSRR, "SSRR" },
{ IPOPT_LSRR, "LSRR" },
{ IPOPT_RA, "RA" },
{ 0, NULL }
};
/*
* print the recorded route in an IP RR, LSRR or SSRR option.
*/
static void
ip_printroute(register const u_char *cp, u_int length)
{
register u_int ptr;
register u_int len;
if (length < 3) {
printf(" [bad length %u]", length);
return;
}
if ((length + 1) & 3)
printf(" [bad length %u]", length);
ptr = cp[2] - 1;
if (ptr < 3 || ((ptr + 1) & 3) || ptr > length + 1)
printf(" [bad ptr %u]", cp[2]);
for (len = 3; len < length; len += 4) {
printf(" %s", ipaddr_string(&cp[len]));
if (ptr > len)
printf(",");
}
}
/*
* If source-routing is present and valid, return the final destination.
* Otherwise, return IP destination.
*
* This is used for UDP and TCP pseudo-header in the checksum
* calculation.
*/
u_int32_t
ip_finddst(const struct ip *ip)
{
int length;
int len;
const u_char *cp;
u_int32_t retval;
cp = (const u_char *)(ip + 1);
length = (IP_HL(ip) << 2) - sizeof(struct ip);
for (; length > 0; cp += len, length -= len) {
int tt;
TCHECK(*cp);
tt = *cp;
if (tt == IPOPT_EOL)
break;
else if (tt == IPOPT_NOP)
len = 1;
else {
TCHECK(cp[1]);
len = cp[1];
if (len < 2)
break;
}
TCHECK2(*cp, len);
switch (tt) {
case IPOPT_SSRR:
case IPOPT_LSRR:
if (len < 7)
break;
memcpy(&retval, cp + len - 4, 4);
return retval;
}
}
trunc:
memcpy(&retval, &ip->ip_dst.s_addr, sizeof(u_int32_t));
return retval;
}
static void
ip_printts(register const u_char *cp, u_int length)
{
register u_int ptr;
register u_int len;
int hoplen;
const char *type;
if (length < 4) {
printf("[bad length %u]", length);
return;
}
printf(" TS{");
hoplen = ((cp[3]&0xF) != IPOPT_TS_TSONLY) ? 8 : 4;
if ((length - 4) & (hoplen-1))
printf("[bad length %u]", length);
ptr = cp[2] - 1;
len = 0;
if (ptr < 4 || ((ptr - 4) & (hoplen-1)) || ptr > length + 1)
printf("[bad ptr %u]", cp[2]);
switch (cp[3]&0xF) {
case IPOPT_TS_TSONLY:
printf("TSONLY");
break;
case IPOPT_TS_TSANDADDR:
printf("TS+ADDR");
break;
/*
* prespecified should really be 3, but some ones might send 2
* instead, and the IPOPT_TS_PRESPEC constant can apparently
* have both values, so we have to hard-code it here.
*/
case 2:
printf("PRESPEC2.0");
break;
case 3: /* IPOPT_TS_PRESPEC */
printf("PRESPEC");
break;
default:
printf("[bad ts type %d]", cp[3]&0xF);
goto done;
}
type = " ";
for (len = 4; len < length; len += hoplen) {
if (ptr == len)
type = " ^ ";
printf("%s%d@%s", type, EXTRACT_32BITS(&cp[len+hoplen-4]),
hoplen!=8 ? "" : ipaddr_string(&cp[len]));
type = " ";
}
done:
printf("%s", ptr == len ? " ^ " : "");
if (cp[3]>>4)
printf(" [%d hops not recorded]} ", cp[3]>>4);
else
printf("}");
}
/*
* print IP options.
*/
static void
ip_optprint(register const u_char *cp, u_int length)
{
register u_int option_len;
const char *sep = "";
for (; length > 0; cp += option_len, length -= option_len) {
u_int option_code;
printf("%s", sep);
sep = ",";
TCHECK(*cp);
option_code = *cp;
printf("%s",
tok2str(ip_option_values,"unknown %u",option_code));
if (option_code == IPOPT_NOP ||
option_code == IPOPT_EOL)
option_len = 1;
else {
TCHECK(cp[1]);
option_len = cp[1];
if (option_len < 2) {
printf(" [bad length %u]", option_len);
return;
}
}
if (option_len > length) {
printf(" [bad length %u]", option_len);
return;
}
TCHECK2(*cp, option_len);
switch (option_code) {
case IPOPT_EOL:
return;
case IPOPT_TS:
ip_printts(cp, option_len);
break;
case IPOPT_RR: /* fall through */
case IPOPT_SSRR:
case IPOPT_LSRR:
ip_printroute(cp, option_len);
break;
case IPOPT_RA:
if (option_len < 4) {
printf(" [bad length %u]", option_len);
break;
}
TCHECK(cp[3]);
if (EXTRACT_16BITS(&cp[2]) != 0)
printf(" value %u", EXTRACT_16BITS(&cp[2]));
break;
case IPOPT_NOP: /* nothing to print - fall through */
case IPOPT_SECURITY:
default:
break;
}
}
return;
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[] = {
{ IP_MF, "+" },
{ IP_DF, "DF" },
{ IP_RES, "rsvd" }, /* The RFC3514 evil ;-) bit */
{ 0, NULL }
};
struct ip_print_demux_state {
const struct ip *ip;
const u_char *cp;
u_int len, off;
u_char nh;
int advance;
};
static void
ip_print_demux(netdissect_options *ndo,
struct ip_print_demux_state *ipds)
{
struct protoent *proto;
again:
switch (ipds->nh) {
case IPPROTO_AH:
ipds->nh = *ipds->cp;
ipds->advance = ah_print(ipds->cp);
if (ipds->advance <= 0)
break;
ipds->cp += ipds->advance;
ipds->len -= ipds->advance;
goto again;
case IPPROTO_ESP:
{
int enh, padlen;
ipds->advance = esp_print(ndo, ipds->cp, ipds->len,
(const u_char *)ipds->ip,
&enh, &padlen);
if (ipds->advance <= 0)
break;
ipds->cp += ipds->advance;
ipds->len -= ipds->advance + padlen;
ipds->nh = enh & 0xff;
goto again;
}
case IPPROTO_IPCOMP:
{
int enh;
ipds->advance = ipcomp_print(ipds->cp, &enh);
if (ipds->advance <= 0)
break;
ipds->cp += ipds->advance;
ipds->len -= ipds->advance;
ipds->nh = enh & 0xff;
goto again;
}
case IPPROTO_SCTP:
sctp_print(ipds->cp, (const u_char *)ipds->ip, ipds->len);
break;
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
* page lists 9 as "any private interior gateway
* (used by Cisco for their IGRP)" and 88 as
* "EIGRP" from Cisco.
*
* Recent BSD <netinet/in.h> headers define
* IP_PROTO_PIGP as 9 and IP_PROTO_IGRP as 88.
* We define IP_PROTO_PIGP as 9 and
* IP_PROTO_EIGRP as 88; those names better
* match was the current protocol number
* assignments say.
*/
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;
case IPPROTO_EGP:
egp_print(ipds->cp, ipds->len);
break;
case IPPROTO_OSPF:
ospf_print(ipds->cp, ipds->len, (const u_char *)ipds->ip);
break;
case IPPROTO_IGMP:
igmp_print(ipds->cp, ipds->len);
break;
case IPPROTO_IPV4:
/* DVMRP multicast tunnel (ip-in-ip encapsulation) */
ip_print(gndo, ipds->cp, ipds->len);
if (! vflag) {
ND_PRINT((ndo, " (ipip-proto-4)"));
return;
}
break;
#ifdef INET6
case IPPROTO_IPV6:
/* ip6-in-ip encapsulation */
ip6_print(ipds->cp, ipds->len);
break;
#endif /*INET6*/
case IPPROTO_RSVP:
rsvp_print(ipds->cp, ipds->len);
break;
case IPPROTO_GRE:
/* do it */
gre_print(ipds->cp, ipds->len);
break;
case IPPROTO_MOBILE:
mobile_print(ipds->cp, ipds->len);
break;
case IPPROTO_PIM:
pim_print(ipds->cp, ipds->len);
break;
case IPPROTO_VRRP:
vrrp_print(ipds->cp, ipds->len, ipds->ip->ip_ttl);
break;
case IPPROTO_PGM:
pgm_print(ipds->cp, ipds->len, (const u_char *)ipds->ip);
break;
default:
if ((proto = getprotobynumber(ipds->nh)) != NULL)
ND_PRINT((ndo, " %s", proto->p_name));
else
ND_PRINT((ndo, " ip-proto-%d", ipds->nh));
ND_PRINT((ndo, " %d", ipds->len));
break;
}
}
void
ip_print_inner(netdissect_options *ndo,
const u_char *bp,
u_int length, u_int nh,
const u_char *bp2)
{
struct ip_print_demux_state ipd;
ipd.ip = (const struct ip *)bp2;
ipd.cp = bp;
ipd.len = length;
ipd.off = 0;
ipd.nh = nh;
ipd.advance = 0;
ip_print_demux(ndo, &ipd);
}
/*
* print an IP datagram.
*/
void
ip_print(netdissect_options *ndo,
const u_char *bp,
u_int length)
{
struct ip_print_demux_state ipd;
struct ip_print_demux_state *ipds=&ipd;
const u_char *ipend;
u_int hlen;
u_int16_t sum, ip_sum;
struct protoent *proto;
ipds->ip = (const struct ip *)bp;
if (IP_V(ipds->ip) != 4) { /* print version if != 4 */
printf("IP%u ", IP_V(ipds->ip));
if (IP_V(ipds->ip) == 6)
printf(", wrong link-layer encapsulation");
}
else if (!eflag)
printf("IP ");
if ((u_char *)(ipds->ip + 1) > snapend) {
printf("[|ip]");
return;
}
if (length < sizeof (struct ip)) {
(void)printf("truncated-ip %u", length);
return;
}
hlen = IP_HL(ipds->ip) * 4;
if (hlen < sizeof (struct ip)) {
(void)printf("bad-hlen %u", hlen);
return;
}
ipds->len = EXTRACT_16BITS(&ipds->ip->ip_len);
if (length < ipds->len)
(void)printf("truncated-ip - %u bytes missing! ",
ipds->len - length);
if (ipds->len < hlen) {
#ifdef GUESS_TSO
if (ipds->len) {
(void)printf("bad-len %u", ipds->len);
return;
}
else {
/* we guess that it is a TSO send */
ipds->len = length;
}
#else
(void)printf("bad-len %u", ipds->len);
return;
#endif /* GUESS_TSO */
}
/*
* Cut off the snapshot length to the end of the IP payload.
*/
ipend = bp + ipds->len;
if (ipend < snapend)
snapend = ipend;
ipds->len -= hlen;
ipds->off = EXTRACT_16BITS(&ipds->ip->ip_off);
if (vflag) {
(void)printf("(tos 0x%x", (int)ipds->ip->ip_tos);
/* ECN bits */
if (ipds->ip->ip_tos & 0x03) {
switch (ipds->ip->ip_tos & 0x03) {
case 1:
(void)printf(",ECT(1)");
break;
case 2:
(void)printf(",ECT(0)");
break;
case 3:
(void)printf(",CE");
}
}
if (ipds->ip->ip_ttl >= 1)
(void)printf(", ttl %3u", ipds->ip->ip_ttl);
/*
* for the firewall guys, print id, offset.
* On all but the last stick a "+" in the flags portion.
* For unfragmented datagrams, note the don't fragment flag.
*/
(void)printf(", id %u, offset %u, flags [%s], proto: %s (%u)",
EXTRACT_16BITS(&ipds->ip->ip_id),
(ipds->off & 0x1fff) * 8,
bittok2str(ip_frag_values, "none", ipds->off&0xe000 ),
tok2str(ipproto_values,"unknown",ipds->ip->ip_p),
ipds->ip->ip_p);
(void)printf(", length: %u", EXTRACT_16BITS(&ipds->ip->ip_len));
if ((hlen - sizeof(struct ip)) > 0) {
printf(", options (");
ip_optprint((u_char *)(ipds->ip + 1), hlen - sizeof(struct ip));
printf(")");
}
if ((u_char *)ipds->ip + hlen <= snapend) {
sum = in_cksum((const u_short *)ipds->ip, hlen, 0);
if (sum != 0) {
ip_sum = EXTRACT_16BITS(&ipds->ip->ip_sum);
(void)printf(", bad cksum %x (->%x)!", ip_sum,
in_cksum_shouldbe(ip_sum, sum));
}
}
printf(") ");
}
/*
* If this is fragment zero, hand it to the next higher
* level protocol.
*/
if ((ipds->off & 0x1fff) == 0) {
ipds->cp = (const u_char *)ipds->ip + hlen;
ipds->nh = ipds->ip->ip_p;
if (ipds->nh != IPPROTO_TCP && ipds->nh != IPPROTO_UDP &&
ipds->nh != IPPROTO_SCTP && ipds->nh != IPPROTO_DCCP) {
(void)printf("%s > %s: ",
ipaddr_string(&ipds->ip->ip_src),
ipaddr_string(&ipds->ip->ip_dst));
}
ip_print_demux(ndo, ipds);
} else {
/* Ultra quiet now means that all this stuff should be suppressed */
if (qflag > 1) return;
/*
* if this isn't the first frag, we're missing the
* next level protocol header. print the ip addr
* and the protocol.
*/
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)
(void)printf(" %s", proto->p_name);
else
(void)printf(" ip-proto-%d", ipds->ip->ip_p);
}
}
}
void
ipN_print(register const u_char *bp, register u_int length)
{
struct ip *ip, hdr;
ip = (struct ip *)bp;
if (length < 4) {
(void)printf("truncated-ip %d", length);
return;
}
memcpy (&hdr, (char *)ip, 4);
switch (IP_V(&hdr)) {
case 4:
ip_print (gndo, bp, length);
return;
#ifdef INET6
case 6:
ip6_print (bp, length);
return;
#endif
default:
(void)printf("unknown ip %d", IP_V(&hdr));
return;
}
}
/*
* Local Variables:
* c-style: whitesmith
* c-basic-offset: 8
* End:
*/
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