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/* $OpenBSD: print-gre.c,v 1.6 2002/10/30 03:04:04 fgsch Exp $ */

/*
* Copyright (c) 2002 Jason L. Wright (jason@thought.net)
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by Jason L. Wright
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/

/*
* tcpdump filter for GRE - Generic Routing Encapsulation
* RFC1701 (GRE), RFC1702 (GRE IPv4), and RFC2637 (Enhanced GRE)
*/

#ifndef lint
static const char rcsid[] _U_ =
    "@(#) $Header: /tcpdump/master/tcpdump/print-gre.c,v 1.28 2005-04-06 21:32:39 mcr Exp $ (LBL)";
#endif

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <tcpdump-stdinc.h>

#include <stdio.h>
#include <string.h>

#include "interface.h"
#include "addrtoname.h"
#include "extract.h"

#include "ip.h"
#include "ethertype.h"

#define GRE_CP 0x8000 /* checksum present */
#define GRE_RP 0x4000 /* routing present */
#define GRE_KP 0x2000 /* key present */
#define GRE_SP 0x1000 /* sequence# present */
#define GRE_sP 0x0800 /* source routing */
#define GRE_RECRS 0x0700 /* recursion count */
#define GRE_AP 0x0080 /* acknowledgment# present */

struct tok gre_flag_values[] = {
    { GRE_CP, "checksum present"},
    { GRE_RP, "routing present"},
    { GRE_KP, "key present"},
    { GRE_SP, "sequence# present"},
    { GRE_sP, "source routing present"},
    { GRE_RECRS, "recursion count"},
    { GRE_AP, "ack present"},
    { 0, NULL }
};

#define GRE_VERS_MASK 0x0007 /* protocol version */

/* source route entry types */
#define GRESRE_IP 0x0800 /* IP */
#define GRESRE_ASN 0xfffe /* ASN */

void gre_print_0(const u_char *, u_int);
void gre_print_1(const u_char *, u_int);
void gre_sre_print(u_int16_t, u_int8_t, u_int8_t, const u_char *, u_int);
void gre_sre_ip_print(u_int8_t, u_int8_t, const u_char *, u_int);
void gre_sre_asn_print(u_int8_t, u_int8_t, const u_char *, u_int);

void
gre_print(const u_char *bp, u_int length)
{
u_int len = length, vers;

if (len < 2) {
printf("[|gre]");
return;
}
vers = EXTRACT_16BITS(bp) & GRE_VERS_MASK;
        printf("GREv%u",vers);

        switch(vers) {
        case 0:
            gre_print_0(bp, len);
            break;
        case 1:
            gre_print_1(bp, len);
            break;
default:
            printf(" ERROR: unknown-version");
            break;
        }
return;

}

void
gre_print_0(const u_char *bp, u_int length)
{
u_int len = length;
u_int16_t flags, prot;

flags = EXTRACT_16BITS(bp);
        if (vflag)
            printf(", Flags [%s]",
                   bittok2str(gre_flag_values,"none",flags));

len -= 2;
bp += 2;

if (len < 2)
goto trunc;
prot = EXTRACT_16BITS(bp);
len -= 2;
bp += 2;

if ((flags & GRE_CP) | (flags & GRE_RP)) {
if (len < 2)
goto trunc;
if (vflag)
printf(", sum 0x%x", EXTRACT_16BITS(bp));
bp += 2;
len -= 2;

if (len < 2)
goto trunc;
printf(", off 0x%x", EXTRACT_16BITS(bp));
bp += 2;
len -= 2;
}

if (flags & GRE_KP) {
if (len < 4)
goto trunc;
printf(", key=0x%x", EXTRACT_32BITS(bp));
bp += 4;
len -= 4;
}

if (flags & GRE_SP) {
if (len < 4)
goto trunc;
printf(", seq %u", EXTRACT_32BITS(bp));
bp += 4;
len -= 4;
}

if (flags & GRE_RP) {
for (;;) {
u_int16_t af;
u_int8_t sreoff;
u_int8_t srelen;

if (len < 4)
goto trunc;
af = EXTRACT_16BITS(bp);
sreoff = *(bp + 2);
srelen = *(bp + 3);
bp += 4;
len -= 4;

if (af == 0 && srelen == 0)
break;

gre_sre_print(af, sreoff, srelen, bp, len);

if (len < srelen)
goto trunc;
bp += srelen;
len -= srelen;
}
}

        if (eflag)
            printf(", proto %s (0x%04x)",
                   tok2str(ethertype_values,"unknown",prot),
                   prot);

        printf(", length %u",length);

        if (vflag < 1)
            printf(": "); /* put in a colon as protocol demarc */
        else
            printf("\n\t"); /* if verbose go multiline */

switch (prot) {
case ETHERTYPE_IP:
ip_print(gndo, bp, len);
break;
#ifdef INET6
case ETHERTYPE_IPV6:
ip6_print(gndo, bp, len);
break;
#endif
case ETHERTYPE_MPLS:
mpls_print(bp, len);
break;
case ETHERTYPE_IPX:
ipx_print(bp, len);
break;
case ETHERTYPE_ATALK:
atalk_print(bp, len);
break;
case ETHERTYPE_GRE_ISO:
isoclns_print(bp, len, len);
break;
case ETHERTYPE_TEB:
ether_print(gndo, bp, len, len, NULL, NULL);
break;
default:
printf("gre-proto-0x%x", prot);
}
return;

trunc:
printf("[|gre]");
}

void
gre_print_1(const u_char *bp, u_int length)
{
u_int len = length;
u_int16_t flags, prot;

flags = EXTRACT_16BITS(bp);
len -= 2;
bp += 2;

if (vflag)
            printf(", Flags [%s]",
                   bittok2str(gre_flag_values,"none",flags));

if (len < 2)
goto trunc;
prot = EXTRACT_16BITS(bp);
len -= 2;
bp += 2;


if (flags & GRE_KP) {
u_int32_t k;

if (len < 4)
goto trunc;
k = EXTRACT_32BITS(bp);
printf(", call %d", k & 0xffff);
len -= 4;
bp += 4;
}

if (flags & GRE_SP) {
if (len < 4)
goto trunc;
printf(", seq %u", EXTRACT_32BITS(bp));
bp += 4;
len -= 4;
}

if (flags & GRE_AP) {
if (len < 4)
goto trunc;
printf(", ack %u", EXTRACT_32BITS(bp));
bp += 4;
len -= 4;
}

if ((flags & GRE_SP) == 0)
printf(", no-payload");

        if (eflag)
            printf(", proto %s (0x%04x)",
                   tok2str(ethertype_values,"unknown",prot),
                   prot);

        printf(", length %u",length);

        if ((flags & GRE_SP) == 0)
            return;

        if (vflag < 1)
            printf(": "); /* put in a colon as protocol demarc */
        else
            printf("\n\t"); /* if verbose go multiline */

switch (prot) {
case ETHERTYPE_PPP:
                ppp_print(bp, len);
break;
default:
printf("gre-proto-0x%x", prot);
break;
}
return;

trunc:
printf("[|gre]");
}

void
gre_sre_print(u_int16_t af, u_int8_t sreoff, u_int8_t srelen,
    const u_char *bp, u_int len)
{
switch (af) {
case GRESRE_IP:
printf(", (rtaf=ip");
gre_sre_ip_print(sreoff, srelen, bp, len);
printf(") ");
break;
case GRESRE_ASN:
printf(", (rtaf=asn");
gre_sre_asn_print(sreoff, srelen, bp, len);
printf(") ");
break;
default:
printf(", (rtaf=0x%x) ", af);
}
}
void
gre_sre_ip_print(u_int8_t sreoff, u_int8_t srelen, const u_char *bp, u_int len)
{
struct in_addr a;
const u_char *up = bp;

if (sreoff & 3) {
printf(", badoffset=%u", sreoff);
return;
}
if (srelen & 3) {
printf(", badlength=%u", srelen);
return;
}
if (sreoff >= srelen) {
printf(", badoff/len=%u/%u", sreoff, srelen);
return;
}

for (;;) {
if (len < 4 || srelen == 0)
return;

memcpy(&a, bp, sizeof(a));
printf(" %s%s",
((bp - up) == sreoff) ? "*" : "",
inet_ntoa(a));

bp += 4;
len -= 4;
srelen -= 4;
}
}

void
gre_sre_asn_print(u_int8_t sreoff, u_int8_t srelen, const u_char *bp, u_int len)
{
const u_char *up = bp;

if (sreoff & 1) {
printf(", badoffset=%u", sreoff);
return;
}
if (srelen & 1) {
printf(", badlength=%u", srelen);
return;
}
if (sreoff >= srelen) {
printf(", badoff/len=%u/%u", sreoff, srelen);
return;
}

for (;;) {
if (len < 2 || srelen == 0)
return;

printf(" %s%x",
((bp - up) == sreoff) ? "*" : "",
EXTRACT_16BITS(bp));

bp += 2;
len -= 2;
srelen -= 2;
}
}
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