/*	$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 lintstatic 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);voidgre_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;}voidgre_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(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;	default:		printf("gre-proto-0x%x", prot);	}	return;trunc:	printf("[|gre]");}voidgre_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]");}voidgre_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);	}}voidgre_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;	}}voidgre_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;	}}