399 lines
9.2 KiB
C
399 lines
9.2 KiB
C
/* $OpenBSD: print-gre.c,v 1.6 2002/10/30 03:04:04 fgsch Exp $ */
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/*
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* Copyright (c) 2002 Jason L. Wright (jason@thought.net)
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by Jason L. Wright
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* 4. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
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* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* tcpdump filter for GRE - Generic Routing Encapsulation
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* RFC1701 (GRE), RFC1702 (GRE IPv4), and RFC2637 (Enhanced GRE)
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*/
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#define NETDISSECT_REWORKED
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <tcpdump-stdinc.h>
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#include <string.h>
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#include "interface.h"
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#include "extract.h"
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#include "ethertype.h"
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static const char tstr[] = "[|gre]";
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#define GRE_CP 0x8000 /* checksum present */
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#define GRE_RP 0x4000 /* routing present */
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#define GRE_KP 0x2000 /* key present */
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#define GRE_SP 0x1000 /* sequence# present */
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#define GRE_sP 0x0800 /* source routing */
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#define GRE_RECRS 0x0700 /* recursion count */
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#define GRE_AP 0x0080 /* acknowledgment# present */
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static const struct tok gre_flag_values[] = {
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{ GRE_CP, "checksum present"},
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{ GRE_RP, "routing present"},
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{ GRE_KP, "key present"},
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{ GRE_SP, "sequence# present"},
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{ GRE_sP, "source routing present"},
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{ GRE_RECRS, "recursion count"},
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{ GRE_AP, "ack present"},
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{ 0, NULL }
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};
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#define GRE_VERS_MASK 0x0007 /* protocol version */
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/* source route entry types */
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#define GRESRE_IP 0x0800 /* IP */
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#define GRESRE_ASN 0xfffe /* ASN */
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static void gre_print_0(netdissect_options *, const u_char *, u_int);
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static void gre_print_1(netdissect_options *, const u_char *, u_int);
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static void gre_sre_print(netdissect_options *, uint16_t, uint8_t, uint8_t, const u_char *, u_int);
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static void gre_sre_ip_print(netdissect_options *, uint8_t, uint8_t, const u_char *, u_int);
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static void gre_sre_asn_print(netdissect_options *, uint8_t, uint8_t, const u_char *, u_int);
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void
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gre_print(netdissect_options *ndo, const u_char *bp, u_int length)
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{
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u_int len = length, vers;
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if (len < 2) {
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ND_PRINT((ndo, "%s", tstr));
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return;
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}
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vers = EXTRACT_16BITS(bp) & GRE_VERS_MASK;
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ND_PRINT((ndo, "GREv%u",vers));
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switch(vers) {
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case 0:
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gre_print_0(ndo, bp, len);
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break;
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case 1:
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gre_print_1(ndo, bp, len);
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break;
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default:
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ND_PRINT((ndo, " ERROR: unknown-version"));
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break;
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}
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}
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static void
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gre_print_0(netdissect_options *ndo, const u_char *bp, u_int length)
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{
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u_int len = length;
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uint16_t flags, prot;
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flags = EXTRACT_16BITS(bp);
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if (ndo->ndo_vflag)
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ND_PRINT((ndo, ", Flags [%s]",
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bittok2str(gre_flag_values,"none",flags)));
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len -= 2;
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bp += 2;
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if (len < 2)
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goto trunc;
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prot = EXTRACT_16BITS(bp);
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len -= 2;
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bp += 2;
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if ((flags & GRE_CP) | (flags & GRE_RP)) {
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if (len < 2)
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goto trunc;
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if (ndo->ndo_vflag)
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ND_PRINT((ndo, ", sum 0x%x", EXTRACT_16BITS(bp)));
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bp += 2;
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len -= 2;
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if (len < 2)
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goto trunc;
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ND_PRINT((ndo, ", off 0x%x", EXTRACT_16BITS(bp)));
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bp += 2;
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len -= 2;
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}
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if (flags & GRE_KP) {
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if (len < 4)
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goto trunc;
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ND_PRINT((ndo, ", key=0x%x", EXTRACT_32BITS(bp)));
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bp += 4;
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len -= 4;
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}
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if (flags & GRE_SP) {
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if (len < 4)
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goto trunc;
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ND_PRINT((ndo, ", seq %u", EXTRACT_32BITS(bp)));
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bp += 4;
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len -= 4;
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}
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if (flags & GRE_RP) {
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for (;;) {
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uint16_t af;
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uint8_t sreoff;
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uint8_t srelen;
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if (len < 4)
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goto trunc;
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af = EXTRACT_16BITS(bp);
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sreoff = *(bp + 2);
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srelen = *(bp + 3);
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bp += 4;
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len -= 4;
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if (af == 0 && srelen == 0)
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break;
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gre_sre_print(ndo, af, sreoff, srelen, bp, len);
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if (len < srelen)
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goto trunc;
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bp += srelen;
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len -= srelen;
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}
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}
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if (ndo->ndo_eflag)
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ND_PRINT((ndo, ", proto %s (0x%04x)",
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tok2str(ethertype_values,"unknown",prot),
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prot));
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ND_PRINT((ndo, ", length %u",length));
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if (ndo->ndo_vflag < 1)
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ND_PRINT((ndo, ": ")); /* put in a colon as protocol demarc */
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else
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ND_PRINT((ndo, "\n\t")); /* if verbose go multiline */
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switch (prot) {
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case ETHERTYPE_IP:
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ip_print(ndo, bp, len);
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break;
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#ifdef INET6
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case ETHERTYPE_IPV6:
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ip6_print(ndo, bp, len);
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break;
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#endif
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case ETHERTYPE_MPLS:
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mpls_print(ndo, bp, len);
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break;
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case ETHERTYPE_IPX:
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ipx_print(ndo, bp, len);
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break;
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case ETHERTYPE_ATALK:
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atalk_print(ndo, bp, len);
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break;
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case ETHERTYPE_GRE_ISO:
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isoclns_print(ndo, bp, len, len);
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break;
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case ETHERTYPE_TEB:
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ether_print(ndo, bp, len, len, NULL, NULL);
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break;
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default:
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ND_PRINT((ndo, "gre-proto-0x%x", prot));
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}
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return;
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trunc:
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ND_PRINT((ndo, "%s", tstr));
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}
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static void
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gre_print_1(netdissect_options *ndo, const u_char *bp, u_int length)
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{
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u_int len = length;
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uint16_t flags, prot;
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flags = EXTRACT_16BITS(bp);
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len -= 2;
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bp += 2;
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if (ndo->ndo_vflag)
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ND_PRINT((ndo, ", Flags [%s]",
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bittok2str(gre_flag_values,"none",flags)));
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if (len < 2)
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goto trunc;
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prot = EXTRACT_16BITS(bp);
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len -= 2;
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bp += 2;
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if (flags & GRE_KP) {
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uint32_t k;
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if (len < 4)
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goto trunc;
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k = EXTRACT_32BITS(bp);
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ND_PRINT((ndo, ", call %d", k & 0xffff));
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len -= 4;
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bp += 4;
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}
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if (flags & GRE_SP) {
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if (len < 4)
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goto trunc;
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ND_PRINT((ndo, ", seq %u", EXTRACT_32BITS(bp)));
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bp += 4;
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len -= 4;
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}
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if (flags & GRE_AP) {
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if (len < 4)
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goto trunc;
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ND_PRINT((ndo, ", ack %u", EXTRACT_32BITS(bp)));
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bp += 4;
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len -= 4;
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}
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if ((flags & GRE_SP) == 0)
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ND_PRINT((ndo, ", no-payload"));
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if (ndo->ndo_eflag)
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ND_PRINT((ndo, ", proto %s (0x%04x)",
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tok2str(ethertype_values,"unknown",prot),
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prot));
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ND_PRINT((ndo, ", length %u",length));
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if ((flags & GRE_SP) == 0)
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return;
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if (ndo->ndo_vflag < 1)
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ND_PRINT((ndo, ": ")); /* put in a colon as protocol demarc */
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else
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ND_PRINT((ndo, "\n\t")); /* if verbose go multiline */
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switch (prot) {
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case ETHERTYPE_PPP:
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ppp_print(ndo, bp, len);
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break;
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default:
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ND_PRINT((ndo, "gre-proto-0x%x", prot));
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break;
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}
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return;
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trunc:
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ND_PRINT((ndo, "%s", tstr));
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}
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static void
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gre_sre_print(netdissect_options *ndo, uint16_t af, uint8_t sreoff,
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uint8_t srelen, const u_char *bp, u_int len)
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{
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switch (af) {
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case GRESRE_IP:
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ND_PRINT((ndo, ", (rtaf=ip"));
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gre_sre_ip_print(ndo, sreoff, srelen, bp, len);
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ND_PRINT((ndo, ") "));
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break;
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case GRESRE_ASN:
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ND_PRINT((ndo, ", (rtaf=asn"));
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gre_sre_asn_print(ndo, sreoff, srelen, bp, len);
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ND_PRINT((ndo, ") "));
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break;
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default:
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ND_PRINT((ndo, ", (rtaf=0x%x) ", af));
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}
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}
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static void
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gre_sre_ip_print(netdissect_options *ndo, uint8_t sreoff, uint8_t srelen,
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const u_char *bp, u_int len)
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{
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struct in_addr a;
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const u_char *up = bp;
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if (sreoff & 3) {
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ND_PRINT((ndo, ", badoffset=%u", sreoff));
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return;
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}
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if (srelen & 3) {
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ND_PRINT((ndo, ", badlength=%u", srelen));
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return;
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}
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if (sreoff >= srelen) {
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ND_PRINT((ndo, ", badoff/len=%u/%u", sreoff, srelen));
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return;
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}
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for (;;) {
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if (len < 4 || srelen == 0)
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return;
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memcpy(&a, bp, sizeof(a));
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ND_PRINT((ndo, " %s%s",
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((bp - up) == sreoff) ? "*" : "",
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inet_ntoa(a)));
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bp += 4;
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len -= 4;
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srelen -= 4;
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}
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}
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static void
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gre_sre_asn_print(netdissect_options *ndo, uint8_t sreoff, uint8_t srelen,
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const u_char *bp, u_int len)
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{
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const u_char *up = bp;
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if (sreoff & 1) {
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ND_PRINT((ndo, ", badoffset=%u", sreoff));
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return;
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}
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if (srelen & 1) {
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ND_PRINT((ndo, ", badlength=%u", srelen));
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return;
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}
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if (sreoff >= srelen) {
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ND_PRINT((ndo, ", badoff/len=%u/%u", sreoff, srelen));
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return;
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}
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for (;;) {
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if (len < 2 || srelen == 0)
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return;
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ND_PRINT((ndo, " %s%x",
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((bp - up) == sreoff) ? "*" : "",
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EXTRACT_16BITS(bp)));
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bp += 2;
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len -= 2;
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srelen -= 2;
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}
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}
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