freebsd-dev/contrib/tcpdump/print-tcp.c
Dimitry Andric 05ea86b0c0 In tcpdump's print-tcp.c, avoid increasing alignment when taking the
addresses of members of struct ip, which is packed.  Since the pointers
are only used for memcmp'ing, they can be pointing to void instead.

Note that upstream has removed the src and dst variables, in the mean
time.

MFC after:	3 days
2017-01-07 00:17:01 +00:00

898 lines
34 KiB
C

/* $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
#else
__RCSID("$NetBSD: print-tcp.c,v 1.8 2007/07/24 11:53:48 drochner Exp $");
#endif
#define NETDISSECT_REWORKED
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <tcpdump-stdinc.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(netdissect_options *ndo,
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(netdissect_options *, 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(netdissect_options *ndo,
register const struct ip *ip,
register const struct tcphdr *tp,
register u_int len)
{
return nextproto4_cksum(ndo, ip, (const uint8_t *)tp, len, len,
IPPROTO_TCP);
}
void
tcp_print(netdissect_options *ndo,
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;
uint16_t sport, dport, win, urp;
uint32_t seq, ack, thseq, thack;
u_int utoval;
uint16_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 (!ND_TTEST(tp->th_dport)) {
ND_PRINT((ndo, "%s > %s: [|tcp]",
ipaddr_string(ndo, &ip->ip_src),
ipaddr_string(ndo, &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) {
ND_PRINT((ndo, "%s.%s > %s.%s: ",
ip6addr_string(ndo, &ip6->ip6_src),
tcpport_string(sport),
ip6addr_string(ndo, &ip6->ip6_dst),
tcpport_string(dport)));
} else {
ND_PRINT((ndo, "%s > %s: ",
tcpport_string(sport), tcpport_string(dport)));
}
} else
#endif /*INET6*/
{
if (ip->ip_p == IPPROTO_TCP) {
ND_PRINT((ndo, "%s.%s > %s.%s: ",
ipaddr_string(ndo, &ip->ip_src),
tcpport_string(sport),
ipaddr_string(ndo, &ip->ip_dst),
tcpport_string(dport)));
} else {
ND_PRINT((ndo, "%s > %s: ",
tcpport_string(sport), tcpport_string(dport)));
}
}
if (hlen < sizeof(*tp)) {
ND_PRINT((ndo, " tcp %d [bad hdr length %u - too short, < %lu]",
length - hlen, hlen, (unsigned long)sizeof(*tp)));
return;
}
ND_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 (ndo->ndo_qflag) {
ND_PRINT((ndo, "tcp %d", length - hlen));
if (hlen > length) {
ND_PRINT((ndo, " [bad hdr length %u - too long, > %u]",
hlen, length));
}
return;
}
flags = tp->th_flags;
ND_PRINT((ndo, "Flags [%s]", bittok2str_nosep(tcp_flag_values, "none", flags)));
if (!ndo->ndo_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 void *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 void *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) {
ND_PRINT((ndo, " [bad hdr length %u - too long, > %u]",
hlen, length));
return;
}
if (ndo->ndo_vflag && !ndo->ndo_Kflag && !fragmented) {
/* Check the checksum, if possible. */
uint16_t sum, tcp_sum;
if (IP_V(ip) == 4) {
if (ND_TTEST2(tp->th_sport, length)) {
sum = tcp_cksum(ndo, ip, tp, length);
tcp_sum = EXTRACT_16BITS(&tp->th_sum);
ND_PRINT((ndo, ", cksum 0x%04x", tcp_sum));
if (sum != 0)
ND_PRINT((ndo, " (incorrect -> 0x%04x)",
in_cksum_shouldbe(tcp_sum, sum)));
else
ND_PRINT((ndo, " (correct)"));
}
}
#ifdef INET6
else if (IP_V(ip) == 6 && ip6->ip6_plen) {
if (ND_TTEST2(tp->th_sport, length)) {
sum = nextproto6_cksum(ip6, (const uint8_t *)tp,
length, length, IPPROTO_TCP);
tcp_sum = EXTRACT_16BITS(&tp->th_sum);
ND_PRINT((ndo, ", cksum 0x%04x", tcp_sum));
if (sum != 0)
ND_PRINT((ndo, " (incorrect -> 0x%04x)",
in_cksum_shouldbe(tcp_sum, sum)));
else
ND_PRINT((ndo, " (correct)"));
}
}
#endif
}
length -= hlen;
if (ndo->ndo_vflag > 1 || length > 0 || flags & (TH_SYN | TH_FIN | TH_RST)) {
ND_PRINT((ndo, ", seq %u", seq));
if (length > 0) {
ND_PRINT((ndo, ":%u", seq + length));
}
}
if (flags & TH_ACK) {
ND_PRINT((ndo, ", ack %u", ack));
}
ND_PRINT((ndo, ", win %d", win));
if (flags & TH_URG)
ND_PRINT((ndo, ", 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);
ND_PRINT((ndo, ", options ["));
while (hlen > 0) {
if (ch != '\0')
ND_PRINT((ndo, "%c", ch));
ND_TCHECK(*cp);
opt = *cp++;
if (ZEROLENOPT(opt))
len = 1;
else {
ND_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; ND_TCHECK2(*cp, l); }
ND_PRINT((ndo, "%s", tok2str(tcp_option_values, "unknown-%u", opt)));
switch (opt) {
case TCPOPT_MAXSEG:
datalen = 2;
LENCHECK(datalen);
ND_PRINT((ndo, " %u", EXTRACT_16BITS(cp)));
break;
case TCPOPT_WSCALE:
datalen = 1;
LENCHECK(datalen);
ND_PRINT((ndo, " %u", *cp));
break;
case TCPOPT_SACK:
datalen = len - 2;
if (datalen % 8 != 0) {
ND_PRINT((ndo, "malformed sack"));
} else {
uint32_t s, e;
ND_PRINT((ndo, " %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;
}
ND_PRINT((ndo, "{%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);
ND_PRINT((ndo, " %u", EXTRACT_32BITS(cp)));
break;
case TCPOPT_TIMESTAMP:
datalen = 8;
LENCHECK(datalen);
ND_PRINT((ndo, " 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(ndo, ip, tp,
bp + TH_OFF(tp) * 4, length, cp)) {
case SIGNATURE_VALID:
ND_PRINT((ndo, "valid"));
break;
case SIGNATURE_INVALID:
ND_PRINT((ndo, "invalid"));
break;
case CANT_CHECK_SIGNATURE:
ND_PRINT((ndo, "can't check - "));
for (i = 0; i < TCP_SIGLEN; ++i)
ND_PRINT((ndo, "%02x", cp[i]));
break;
}
#else
for (i = 0; i < TCP_SIGLEN; ++i)
ND_PRINT((ndo, "%02x", cp[i]));
#endif
break;
case TCPOPT_AUTH:
ND_PRINT((ndo, "keyid %d", *cp++));
datalen = len - 3;
for (i = 0; i < datalen; ++i) {
LENCHECK(i);
ND_PRINT((ndo, "%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);
ND_PRINT((ndo, "0x%x", utoval));
if (utoval & 0x0001)
utoval = (utoval >> 1) * 60;
else
utoval >>= 1;
ND_PRINT((ndo, " %u", utoval));
break;
case TCPOPT_MPTCP:
datalen = len - 2;
LENCHECK(datalen);
if (!mptcp_print(ndo, 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);
ND_PRINT((ndo, "-"));
switch(magic) {
case 0xf989:
/* TCP Fast Open: RFC 7413 */
if (datalen == 2) {
/* Fast Open Cookie Request */
ND_PRINT((ndo, "tfo cookiereq"));
} else {
/* Fast Open Cookie */
if (datalen % 2 != 0 || datalen < 6 || datalen > 18) {
ND_PRINT((ndo, "tfo malformed"));
} else {
ND_PRINT((ndo, "tfo cookie "));
for (i = 2; i < datalen; ++i)
ND_PRINT((ndo, "%02x", cp[i]));
}
}
break;
default:
/* Unknown magic number */
ND_PRINT((ndo, "%04x", magic));
break;
}
break;
default:
datalen = len - 2;
if (datalen)
ND_PRINT((ndo, " 0x"));
for (i = 0; i < datalen; ++i) {
LENCHECK(i);
ND_PRINT((ndo, "%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)
ND_PRINT((ndo, "[len %d]", len));
ch = ',';
if (opt == TCPOPT_EOL)
break;
}
ND_PRINT((ndo, "]"));
}
/*
* Print length field before crawling down the stack.
*/
ND_PRINT((ndo, ", length %u", length));
if (length <= 0)
return;
/*
* Decode payload if necessary.
*/
bp += TH_OFF(tp) * 4;
if ((flags & TH_RST) && ndo->ndo_vflag) {
print_tcp_rst_data(ndo, bp, length);
return;
}
if (ndo->ndo_packettype) {
switch (ndo->ndo_packettype) {
case PT_ZMTP1:
zmtp1_print(ndo, bp, length);
break;
}
return;
}
if (sport == TELNET_PORT || dport == TELNET_PORT) {
telnet_print(ndo, bp, length);
} else if (sport == SMTP_PORT || dport == SMTP_PORT) {
ND_PRINT((ndo, ": "));
smtp_print(ndo, bp, length);
} else if (sport == BGP_PORT || dport == BGP_PORT)
bgp_print(ndo, bp, length);
else if (sport == PPTP_PORT || dport == PPTP_PORT)
pptp_print(ndo, bp);
#ifdef TCPDUMP_DO_SMB
else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT)
nbt_tcp_print(ndo, bp, length);
else if (sport == SMB_PORT || dport == SMB_PORT)
smb_tcp_print(ndo, bp, length);
#endif
else if (sport == BEEP_PORT || dport == BEEP_PORT)
beep_print(ndo, bp, length);
else if (sport == OPENFLOW_PORT_OLD || dport == OPENFLOW_PORT_OLD ||
sport == OPENFLOW_PORT_IANA || dport == OPENFLOW_PORT_IANA)
openflow_print(ndo, bp, length);
else if (sport == FTP_PORT || dport == FTP_PORT) {
ND_PRINT((ndo, ": "));
ftp_print(ndo, bp, length);
} else if (sport == HTTP_PORT || dport == HTTP_PORT ||
sport == HTTP_PORT_ALT || dport == HTTP_PORT_ALT) {
ND_PRINT((ndo, ": "));
http_print(ndo, bp, length);
} else if (sport == RTSP_PORT || dport == RTSP_PORT ||
sport == RTSP_PORT_ALT || dport == RTSP_PORT_ALT) {
ND_PRINT((ndo, ": "));
rtsp_print(ndo, 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(ndo, bp + 2, length - 2, 0);
} else if (sport == MSDP_PORT || dport == MSDP_PORT) {
msdp_print(ndo, bp, length);
} else if (sport == RPKI_RTR_PORT || dport == RPKI_RTR_PORT) {
rpki_rtr_print(ndo, bp, length);
}
else if (length > 0 && (sport == LDP_PORT || dport == LDP_PORT)) {
ldp_print(ndo, bp, length);
}
else if ((sport == NFS_PORT || dport == NFS_PORT) &&
length >= 4 && ND_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.
*/
uint32_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 (ND_TTEST(rp->rm_direction)) {
direction = (enum sunrpc_msg_type)EXTRACT_32BITS(&rp->rm_direction);
if (dport == NFS_PORT && direction == SUNRPC_CALL) {
ND_PRINT((ndo, ": NFS request xid %u ", EXTRACT_32BITS(&rp->rm_xid)));
nfsreq_print_noaddr(ndo, (u_char *)rp, fraglen, (u_char *)ip);
return;
}
if (sport == NFS_PORT && direction == SUNRPC_REPLY) {
ND_PRINT((ndo, ": NFS reply xid %u ", EXTRACT_32BITS(&rp->rm_xid)));
nfsreply_print_noaddr(ndo, (u_char *)rp, fraglen, (u_char *)ip);
return;
}
}
}
return;
bad:
ND_PRINT((ndo, "[bad opt]"));
if (ch != '\0')
ND_PRINT((ndo, ">"));
return;
trunc:
ND_PRINT((ndo, "[|tcp]"));
if (ch != '\0')
ND_PRINT((ndo, ">"));
}
/*
* 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(netdissect_options *ndo,
register const u_char *sp, u_int length)
{
int c;
ND_PRINT((ndo, ND_TTEST2(*sp, length) ? " [RST" : " [!RST"));
if (length > MAX_RST_DATA_LEN) {
length = MAX_RST_DATA_LEN; /* can use -X for longer */
ND_PRINT((ndo, "+")); /* indicate we truncate */
}
ND_PRINT((ndo, " "));
while (length-- && sp <= ndo->ndo_snapend) {
c = *sp++;
safeputchar(ndo, c);
}
ND_PRINT((ndo, "]"));
}
#ifdef HAVE_LIBCRYPTO
USES_APPLE_DEPRECATED_API
static int
tcp_verify_signature(netdissect_options *ndo,
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;
uint16_t savecsum, tlen;
#ifdef INET6
struct ip6_hdr *ip6;
uint32_t len32;
uint8_t nxt;
#endif
if (data + length > ndo->ndo_snapend) {
ND_PRINT((ndo, "snaplen too short, "));
return (CANT_CHECK_SIGNATURE);
}
tp1 = *tp;
if (ndo->ndo_sigsecret == NULL) {
ND_PRINT((ndo, "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
ND_PRINT((ndo, "IP version not 4 or 6, "));
#else
ND_PRINT((ndo, "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, ndo->ndo_sigsecret, strlen(ndo->ndo_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:
*/