/* $NetBSD: print-tcp.c,v 1.9 2007/07/26 18:15:12 plunky Exp $ */
/*
* Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
* The Regents of the University of California. All rights reserved.
*
* Copyright (c) 1999-2004 The tcpdump.org project
*
* 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-tcp.c,v 1.135 2008-11-09 23:35:03 mcr Exp $ (LBL)";
#else
__RCSID("$NetBSD: print-tcp.c,v 1.8 2007/07/24 11:53:48 drochner Exp $");
#endif
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <tcpdump-stdinc.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "interface.h"
#include "addrtoname.h"
#include "extract.h"
#include "tcp.h"
#include "ip.h"
#ifdef INET6
#include "ip6.h"
#endif
#include "ipproto.h"
#include "rpc_auth.h"
#include "rpc_msg.h"
#include "nameser.h"
#ifdef HAVE_LIBCRYPTO
#include <openssl/md5.h>
#include <signature.h>
static int tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp,
const u_char *data, int length, const u_char *rcvsig);
#endif
static void print_tcp_rst_data(register const u_char *sp, u_int length);
#define MAX_RST_DATA_LEN 30
struct tha {
struct in_addr src;
struct in_addr dst;
u_int port;
};
struct tcp_seq_hash {
struct tcp_seq_hash *nxt;
struct tha addr;
tcp_seq seq;
tcp_seq ack;
};
#ifdef INET6
struct tha6 {
struct in6_addr src;
struct in6_addr dst;
u_int port;
};
struct tcp_seq_hash6 {
struct tcp_seq_hash6 *nxt;
struct tha6 addr;
tcp_seq seq;
tcp_seq ack;
};
#endif
#define TSEQ_HASHSIZE 919
/* These tcp optinos do not have the size octet */
#define ZEROLENOPT(o) ((o) == TCPOPT_EOL || (o) == TCPOPT_NOP)
static struct tcp_seq_hash tcp_seq_hash4[TSEQ_HASHSIZE];
#ifdef INET6
static struct tcp_seq_hash6 tcp_seq_hash6[TSEQ_HASHSIZE];
#endif
static const struct tok tcp_flag_values[] = {
{ TH_FIN, "F" },
{ TH_SYN, "S" },
{ TH_RST, "R" },
{ TH_PUSH, "P" },
{ TH_ACK, "." },
{ TH_URG, "U" },
{ TH_ECNECHO, "E" },
{ TH_CWR, "W" },
{ 0, NULL }
};
static const struct tok tcp_option_values[] = {
{ TCPOPT_EOL, "eol" },
{ TCPOPT_NOP, "nop" },
{ TCPOPT_MAXSEG, "mss" },
{ TCPOPT_WSCALE, "wscale" },
{ TCPOPT_SACKOK, "sackOK" },
{ TCPOPT_SACK, "sack" },
{ TCPOPT_ECHO, "echo" },
{ TCPOPT_ECHOREPLY, "echoreply" },
{ TCPOPT_TIMESTAMP, "TS" },
{ TCPOPT_CC, "cc" },
{ TCPOPT_CCNEW, "ccnew" },
{ TCPOPT_CCECHO, "" },
{ TCPOPT_SIGNATURE, "md5" },
{ TCPOPT_AUTH, "enhanced auth" },
{ TCPOPT_UTO, "uto" },
{ TCPOPT_MPTCP, "mptcp" },
{ TCPOPT_EXPERIMENT2, "exp" },
{ 0, NULL }
};
static int tcp_cksum(register const struct ip *ip,
register const struct tcphdr *tp,
register u_int len)
{
return (nextproto4_cksum(ip, (const u_int8_t *)tp, len,
IPPROTO_TCP));
}
void
tcp_print(register const u_char *bp, register u_int length,
register const u_char *bp2, int fragmented)
{
register const struct tcphdr *tp;
register const struct ip *ip;
register u_char flags;
register u_int hlen;
register char ch;
u_int16_t sport, dport, win, urp;
u_int32_t seq, ack, thseq, thack;
u_int utoval;
u_int16_t magic;
register int rev;
#ifdef INET6
register const struct ip6_hdr *ip6;
#endif
tp = (struct tcphdr *)bp;
ip = (struct ip *)bp2;
#ifdef INET6
if (IP_V(ip) == 6)
ip6 = (struct ip6_hdr *)bp2;
else
ip6 = NULL;
#endif /*INET6*/
ch = '\0';
if (!TTEST(tp->th_dport)) {
(void)printf("%s > %s: [|tcp]",
ipaddr_string(&ip->ip_src),
ipaddr_string(&ip->ip_dst));
return;
}
sport = EXTRACT_16BITS(&tp->th_sport);
dport = EXTRACT_16BITS(&tp->th_dport);
hlen = TH_OFF(tp) * 4;
#ifdef INET6
if (ip6) {
if (ip6->ip6_nxt == IPPROTO_TCP) {
(void)printf("%s.%s > %s.%s: ",
ip6addr_string(&ip6->ip6_src),
tcpport_string(sport),
ip6addr_string(&ip6->ip6_dst),
tcpport_string(dport));
} else {
(void)printf("%s > %s: ",
tcpport_string(sport), tcpport_string(dport));
}
} else
#endif /*INET6*/
{
if (ip->ip_p == IPPROTO_TCP) {
(void)printf("%s.%s > %s.%s: ",
ipaddr_string(&ip->ip_src),
tcpport_string(sport),
ipaddr_string(&ip->ip_dst),
tcpport_string(dport));
} else {
(void)printf("%s > %s: ",
tcpport_string(sport), tcpport_string(dport));
}
}
if (hlen < sizeof(*tp)) {
(void)printf(" tcp %d [bad hdr length %u - too short, < %lu]",
length - hlen, hlen, (unsigned long)sizeof(*tp));
return;
}
TCHECK(*tp);
seq = EXTRACT_32BITS(&tp->th_seq);
ack = EXTRACT_32BITS(&tp->th_ack);
win = EXTRACT_16BITS(&tp->th_win);
urp = EXTRACT_16BITS(&tp->th_urp);
if (qflag) {
(void)printf("tcp %d", length - hlen);
if (hlen > length) {
(void)printf(" [bad hdr length %u - too long, > %u]",
hlen, length);
}
return;
}
flags = tp->th_flags;
printf("Flags [%s]", bittok2str_nosep(tcp_flag_values, "none", flags));
if (!Sflag && (flags & TH_ACK)) {
/*
* Find (or record) the initial sequence numbers for
* this conversation. (we pick an arbitrary
* collating order so there's only one entry for
* both directions).
*/
rev = 0;
#ifdef INET6
if (ip6) {
register struct tcp_seq_hash6 *th;
struct tcp_seq_hash6 *tcp_seq_hash;
const struct in6_addr *src, *dst;
struct tha6 tha;
tcp_seq_hash = tcp_seq_hash6;
src = &ip6->ip6_src;
dst = &ip6->ip6_dst;
if (sport > dport)
rev = 1;
else if (sport == dport) {
if (UNALIGNED_MEMCMP(src, dst, sizeof ip6->ip6_dst) > 0)
rev = 1;
}
if (rev) {
UNALIGNED_MEMCPY(&tha.src, dst, sizeof ip6->ip6_dst);
UNALIGNED_MEMCPY(&tha.dst, src, sizeof ip6->ip6_src);
tha.port = dport << 16 | sport;
} else {
UNALIGNED_MEMCPY(&tha.dst, dst, sizeof ip6->ip6_dst);
UNALIGNED_MEMCPY(&tha.src, src, sizeof ip6->ip6_src);
tha.port = sport << 16 | dport;
}
for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE];
th->nxt; th = th->nxt)
if (memcmp((char *)&tha, (char *)&th->addr,
sizeof(th->addr)) == 0)
break;
if (!th->nxt || (flags & TH_SYN)) {
/* didn't find it or new conversation */
if (th->nxt == NULL) {
th->nxt = (struct tcp_seq_hash6 *)
calloc(1, sizeof(*th));
if (th->nxt == NULL)
error("tcp_print: calloc");
}
th->addr = tha;
if (rev)
th->ack = seq, th->seq = ack - 1;
else
th->seq = seq, th->ack = ack - 1;
} else {
if (rev)
seq -= th->ack, ack -= th->seq;
else
seq -= th->seq, ack -= th->ack;
}
thseq = th->seq;
thack = th->ack;
} else {
#else /*INET6*/
{
#endif /*INET6*/
register struct tcp_seq_hash *th;
struct tcp_seq_hash *tcp_seq_hash;
const struct in_addr *src, *dst;
struct tha tha;
tcp_seq_hash = tcp_seq_hash4;
src = &ip->ip_src;
dst = &ip->ip_dst;
if (sport > dport)
rev = 1;
else if (sport == dport) {
if (UNALIGNED_MEMCMP(src, dst, sizeof ip->ip_dst) > 0)
rev = 1;
}
if (rev) {
UNALIGNED_MEMCPY(&tha.src, dst, sizeof ip->ip_dst);
UNALIGNED_MEMCPY(&tha.dst, src, sizeof ip->ip_src);
tha.port = dport << 16 | sport;
} else {
UNALIGNED_MEMCPY(&tha.dst, dst, sizeof ip->ip_dst);
UNALIGNED_MEMCPY(&tha.src, src, sizeof ip->ip_src);
tha.port = sport << 16 | dport;
}
for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE];
th->nxt; th = th->nxt)
if (memcmp((char *)&tha, (char *)&th->addr,
sizeof(th->addr)) == 0)
break;
if (!th->nxt || (flags & TH_SYN)) {
/* didn't find it or new conversation */
if (th->nxt == NULL) {
th->nxt = (struct tcp_seq_hash *)
calloc(1, sizeof(*th));
if (th->nxt == NULL)
error("tcp_print: calloc");
}
th->addr = tha;
if (rev)
th->ack = seq, th->seq = ack - 1;
else
th->seq = seq, th->ack = ack - 1;
} else {
if (rev)
seq -= th->ack, ack -= th->seq;
else
seq -= th->seq, ack -= th->ack;
}
thseq = th->seq;
thack = th->ack;
}
} else {
/*fool gcc*/
thseq = thack = rev = 0;
}
if (hlen > length) {
(void)printf(" [bad hdr length %u - too long, > %u]",
hlen, length);
return;
}
if (vflag && !Kflag && !fragmented) {
/* Check the checksum, if possible. */
u_int16_t sum, tcp_sum;
if (IP_V(ip) == 4) {
if (TTEST2(tp->th_sport, length)) {
sum = tcp_cksum(ip, tp, length);
tcp_sum = EXTRACT_16BITS(&tp->th_sum);
(void)printf(", cksum 0x%04x", tcp_sum);
if (sum != 0)
(void)printf(" (incorrect -> 0x%04x)",
in_cksum_shouldbe(tcp_sum, sum));
else
(void)printf(" (correct)");
}
}
#ifdef INET6
else if (IP_V(ip) == 6 && ip6->ip6_plen) {
if (TTEST2(tp->th_sport, length)) {
sum = nextproto6_cksum(ip6, (const u_int8_t *)tp, length, IPPROTO_TCP);
tcp_sum = EXTRACT_16BITS(&tp->th_sum);
(void)printf(", cksum 0x%04x", tcp_sum);
if (sum != 0)
(void)printf(" (incorrect -> 0x%04x)",
in_cksum_shouldbe(tcp_sum, sum));
else
(void)printf(" (correct)");
}
}
#endif
}
length -= hlen;
if (vflag > 1 || length > 0 || flags & (TH_SYN | TH_FIN | TH_RST)) {
(void)printf(", seq %u", seq);
if (length > 0) {
(void)printf(":%u", seq + length);
}
}
if (flags & TH_ACK) {
(void)printf(", ack %u", ack);
}
(void)printf(", win %d", win);
if (flags & TH_URG)
(void)printf(", urg %d", urp);
/*
* Handle any options.
*/
if (hlen > sizeof(*tp)) {
register const u_char *cp;
register u_int i, opt, datalen;
register u_int len;
hlen -= sizeof(*tp);
cp = (const u_char *)tp + sizeof(*tp);
printf(", options [");
while (hlen > 0) {
if (ch != '\0')
putchar(ch);
TCHECK(*cp);
opt = *cp++;
if (ZEROLENOPT(opt))
len = 1;
else {
TCHECK(*cp);
len = *cp++; /* total including type, len */
if (len < 2 || len > hlen)
goto bad;
--hlen; /* account for length byte */
}
--hlen; /* account for type byte */
datalen = 0;
/* Bail if "l" bytes of data are not left or were not captured */
#define LENCHECK(l) { if ((l) > hlen) goto bad; TCHECK2(*cp, l); }
printf("%s", tok2str(tcp_option_values, "unknown-%u", opt));
switch (opt) {
case TCPOPT_MAXSEG:
datalen = 2;
LENCHECK(datalen);
(void)printf(" %u", EXTRACT_16BITS(cp));
break;
case TCPOPT_WSCALE:
datalen = 1;
LENCHECK(datalen);
(void)printf(" %u", *cp);
break;
case TCPOPT_SACK:
datalen = len - 2;
if (datalen % 8 != 0) {
(void)printf("malformed sack");
} else {
u_int32_t s, e;
(void)printf(" %d ", datalen / 8);
for (i = 0; i < datalen; i += 8) {
LENCHECK(i + 4);
s = EXTRACT_32BITS(cp + i);
LENCHECK(i + 8);
e = EXTRACT_32BITS(cp + i + 4);
if (rev) {
s -= thseq;
e -= thseq;
} else {
s -= thack;
e -= thack;
}
(void)printf("{%u:%u}", s, e);
}
}
break;
case TCPOPT_CC:
case TCPOPT_CCNEW:
case TCPOPT_CCECHO:
case TCPOPT_ECHO:
case TCPOPT_ECHOREPLY:
/*
* those options share their semantics.
* fall through
*/
datalen = 4;
LENCHECK(datalen);
(void)printf(" %u", EXTRACT_32BITS(cp));
break;
case TCPOPT_TIMESTAMP:
datalen = 8;
LENCHECK(datalen);
(void)printf(" val %u ecr %u",
EXTRACT_32BITS(cp),
EXTRACT_32BITS(cp + 4));
break;
case TCPOPT_SIGNATURE:
datalen = TCP_SIGLEN;
LENCHECK(datalen);
#ifdef HAVE_LIBCRYPTO
switch (tcp_verify_signature(ip, tp,
bp + TH_OFF(tp) * 4, length, cp)) {
case SIGNATURE_VALID:
(void)printf("valid");
break;
case SIGNATURE_INVALID:
(void)printf("invalid");
break;
case CANT_CHECK_SIGNATURE:
(void)printf("can't check - ");
for (i = 0; i < TCP_SIGLEN; ++i)
(void)printf("%02x", cp[i]);
break;
}
#else
for (i = 0; i < TCP_SIGLEN; ++i)
(void)printf("%02x", cp[i]);
#endif
break;
case TCPOPT_AUTH:
(void)printf("keyid %d", *cp++);
datalen = len - 3;
for (i = 0; i < datalen; ++i) {
LENCHECK(i);
(void)printf("%02x", cp[i]);
}
break;
case TCPOPT_EOL:
case TCPOPT_NOP:
case TCPOPT_SACKOK:
/*
* Nothing interesting.
* fall through
*/
break;
case TCPOPT_UTO:
datalen = 2;
LENCHECK(datalen);
utoval = EXTRACT_16BITS(cp);
(void)printf("0x%x", utoval);
if (utoval & 0x0001)
utoval = (utoval >> 1) * 60;
else
utoval >>= 1;
(void)printf(" %u", utoval);
break;
case TCPOPT_MPTCP:
datalen = len - 2;
LENCHECK(datalen);
if (!mptcp_print(cp-2, len, flags))
goto bad;
break;
case TCPOPT_EXPERIMENT2:
datalen = len - 2;
LENCHECK(datalen);
if (datalen < 2)
goto bad;
/* RFC6994 */
magic = EXTRACT_16BITS(cp);
(void)printf("-");
switch(magic) {
case 0xf989:
/* TCP Fast Open: draft-ietf-tcpm-fastopen-04 */
if (datalen == 2) {
/* Fast Open Cookie Request */
(void)printf("tfo cookiereq");
} else {
/* Fast Open Cookie */
if (datalen % 2 != 0 || datalen < 6 || datalen > 18) {
(void)printf("tfo malformed");
} else {
(void)printf("tfo cookie ");
for (i = 2; i < datalen; ++i)
(void)printf("%02x", cp[i]);
}
}
break;
default:
/* Unknown magic number */
(void)printf("%04x", magic);
break;
}
break;
default:
datalen = len - 2;
if (datalen)
printf(" 0x");
for (i = 0; i < datalen; ++i) {
LENCHECK(i);
(void)printf("%02x", cp[i]);
}
break;
}
/* Account for data printed */
cp += datalen;
hlen -= datalen;
/* Check specification against observed length */
++datalen; /* option octet */
if (!ZEROLENOPT(opt))
++datalen; /* size octet */
if (datalen != len)
(void)printf("[len %d]", len);
ch = ',';
if (opt == TCPOPT_EOL)
break;
}
putchar(']');
}
/*
* Print length field before crawling down the stack.
*/
printf(", length %u", length);
if (length <= 0)
return;
/*
* Decode payload if necessary.
*/
bp += TH_OFF(tp) * 4;
if ((flags & TH_RST) && vflag) {
print_tcp_rst_data(bp, length);
return;
}
if (packettype) {
switch (packettype) {
case PT_ZMTP1:
zmtp1_print(bp, length);
break;
}
return;
}
if (sport == TELNET_PORT || dport == TELNET_PORT) {
if (!qflag && vflag)
telnet_print(bp, length);
} else if (sport == BGP_PORT || dport == BGP_PORT)
bgp_print(bp, length);
else if (sport == PPTP_PORT || dport == PPTP_PORT)
pptp_print(bp);
#ifdef TCPDUMP_DO_SMB
else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT)
nbt_tcp_print(bp, length);
else if (sport == SMB_PORT || dport == SMB_PORT)
smb_tcp_print(bp, length);
#endif
else if (sport == BEEP_PORT || dport == BEEP_PORT)
beep_print(bp, length);
else if (sport == OPENFLOW_PORT || dport == OPENFLOW_PORT)
openflow_print(bp, length);
else if (length > 2 &&
(sport == NAMESERVER_PORT || dport == NAMESERVER_PORT ||
sport == MULTICASTDNS_PORT || dport == MULTICASTDNS_PORT)) {
/*
* TCP DNS query has 2byte length at the head.
* XXX packet could be unaligned, it can go strange
*/
ns_print(bp + 2, length - 2, 0);
} else if (sport == MSDP_PORT || dport == MSDP_PORT) {
msdp_print(bp, length);
} else if (sport == RPKI_RTR_PORT || dport == RPKI_RTR_PORT) {
rpki_rtr_print(bp, length);
}
else if (length > 0 && (sport == LDP_PORT || dport == LDP_PORT)) {
ldp_print(bp, length);
}
else if ((sport == NFS_PORT || dport == NFS_PORT) &&
length >= 4 && TTEST2(*bp, 4)) {
/*
* If data present, header length valid, and NFS port used,
* assume NFS.
* Pass offset of data plus 4 bytes for RPC TCP msg length
* to NFS print routines.
*/
u_int32_t fraglen;
register struct sunrpc_msg *rp;
enum sunrpc_msg_type direction;
fraglen = EXTRACT_32BITS(bp) & 0x7FFFFFFF;
if (fraglen > (length) - 4)
fraglen = (length) - 4;
rp = (struct sunrpc_msg *)(bp + 4);
if (TTEST(rp->rm_direction)) {
direction = (enum sunrpc_msg_type)EXTRACT_32BITS(&rp->rm_direction);
if (dport == NFS_PORT && direction == SUNRPC_CALL) {
(void)printf(": NFS request xid %u ", EXTRACT_32BITS(&rp->rm_xid));
nfsreq_print_noaddr((u_char *)rp, fraglen, (u_char *)ip);
return;
}
if (sport == NFS_PORT && direction == SUNRPC_REPLY) {
(void)printf(": NFS reply xid %u ", EXTRACT_32BITS(&rp->rm_xid));
nfsreply_print_noaddr((u_char *)rp, fraglen, (u_char *)ip);
return;
}
}
}
return;
bad:
fputs("[bad opt]", stdout);
if (ch != '\0')
putchar('>');
return;
trunc:
fputs("[|tcp]", stdout);
if (ch != '\0')
putchar('>');
}
/*
* RFC1122 says the following on data in RST segments:
*
* 4.2.2.12 RST Segment: RFC-793 Section 3.4
*
* A TCP SHOULD allow a received RST segment to include data.
*
* DISCUSSION
* It has been suggested that a RST segment could contain
* ASCII text that encoded and explained the cause of the
* RST. No standard has yet been established for such
* data.
*
*/
static void
print_tcp_rst_data(register const u_char *sp, u_int length)
{
int c;
if (TTEST2(*sp, length))
printf(" [RST");
else
printf(" [!RST");
if (length > MAX_RST_DATA_LEN) {
length = MAX_RST_DATA_LEN; /* can use -X for longer */
putchar('+'); /* indicate we truncate */
}
putchar(' ');
while (length-- && sp <= snapend) {
c = *sp++;
safeputchar(c);
}
putchar(']');
}
#ifdef HAVE_LIBCRYPTO
USES_APPLE_DEPRECATED_API
static int
tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp,
const u_char *data, int length, const u_char *rcvsig)
{
struct tcphdr tp1;
u_char sig[TCP_SIGLEN];
char zero_proto = 0;
MD5_CTX ctx;
u_int16_t savecsum, tlen;
#ifdef INET6
struct ip6_hdr *ip6;
u_int32_t len32;
u_int8_t nxt;
#endif
if (data + length > snapend) {
printf("snaplen too short, ");
return (CANT_CHECK_SIGNATURE);
}
tp1 = *tp;
if (sigsecret == NULL) {
printf("shared secret not supplied with -M, ");
return (CANT_CHECK_SIGNATURE);
}
MD5_Init(&ctx);
/*
* Step 1: Update MD5 hash with IP pseudo-header.
*/
if (IP_V(ip) == 4) {
MD5_Update(&ctx, (char *)&ip->ip_src, sizeof(ip->ip_src));
MD5_Update(&ctx, (char *)&ip->ip_dst, sizeof(ip->ip_dst));
MD5_Update(&ctx, (char *)&zero_proto, sizeof(zero_proto));
MD5_Update(&ctx, (char *)&ip->ip_p, sizeof(ip->ip_p));
tlen = EXTRACT_16BITS(&ip->ip_len) - IP_HL(ip) * 4;
tlen = htons(tlen);
MD5_Update(&ctx, (char *)&tlen, sizeof(tlen));
#ifdef INET6
} else if (IP_V(ip) == 6) {
ip6 = (struct ip6_hdr *)ip;
MD5_Update(&ctx, (char *)&ip6->ip6_src, sizeof(ip6->ip6_src));
MD5_Update(&ctx, (char *)&ip6->ip6_dst, sizeof(ip6->ip6_dst));
len32 = htonl(EXTRACT_16BITS(&ip6->ip6_plen));
MD5_Update(&ctx, (char *)&len32, sizeof(len32));
nxt = 0;
MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
nxt = IPPROTO_TCP;
MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
#endif
} else {
#ifdef INET6
printf("IP version not 4 or 6, ");
#else
printf("IP version not 4, ");
#endif
return (CANT_CHECK_SIGNATURE);
}
/*
* Step 2: Update MD5 hash with TCP header, excluding options.
* The TCP checksum must be set to zero.
*/
savecsum = tp1.th_sum;
tp1.th_sum = 0;
MD5_Update(&ctx, (char *)&tp1, sizeof(struct tcphdr));
tp1.th_sum = savecsum;
/*
* Step 3: Update MD5 hash with TCP segment data, if present.
*/
if (length > 0)
MD5_Update(&ctx, data, length);
/*
* Step 4: Update MD5 hash with shared secret.
*/
MD5_Update(&ctx, sigsecret, strlen(sigsecret));
MD5_Final(sig, &ctx);
if (memcmp(rcvsig, sig, TCP_SIGLEN) == 0)
return (SIGNATURE_VALID);
else
return (SIGNATURE_INVALID);
}
USES_APPLE_RST
#endif /* HAVE_LIBCRYPTO */
/*
* Local Variables:
* c-style: whitesmith
* c-basic-offset: 8
* End:
*/