tcpdump/print-vxlan-gpe.c
Denis Ovsienko e37e1b0c82 VXLAN-GPE: Modernize packet parsing style.
Enable ND_LONGJMP_FROM_TCHECK. Add and use a standard invalid packet
label. Advance one field at a time and decrement the length.
2020-10-17 17:52:29 +01:00

125 lines
3.6 KiB
C

/* Copyright (c) 2015, bugyo
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT OWNER OR CONTRIBUTORS 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.
*/
/* \summary: Generic Protocol Extension for VXLAN (VXLAN GPE) printer */
/* specification: draft-ietf-nvo3-vxlan-gpe-10 */
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include "netdissect-stdinc.h"
#define ND_LONGJMP_FROM_TCHECK
#include "netdissect.h"
#include "extract.h"
static const struct tok vxlan_gpe_flags [] = {
{ 0x08, "I" },
{ 0x04, "P" },
{ 0x02, "B" },
{ 0x01, "O" },
{ 0, NULL }
};
#define VXLAN_GPE_HDR_LEN 8
/*
* VXLAN GPE header, draft-ietf-nvo3-vxlan-gpe-01
* Generic Protocol Extension for VXLAN
*
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* |R|R|Ver|I|P|R|O| Reserved |Next Protocol |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | VXLAN Network Identifier (VNI) | Reserved |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
void
vxlan_gpe_print(netdissect_options *ndo, const u_char *bp, u_int len)
{
uint8_t flags;
uint8_t next_protocol;
uint32_t vni;
ndo->ndo_protocol = "vxlan_gpe";
ND_PRINT("VXLAN-GPE, ");
if (len < VXLAN_GPE_HDR_LEN) {
ND_PRINT(" (len %u < %u)", len, VXLAN_GPE_HDR_LEN);
goto invalid;
}
flags = GET_U_1(bp);
bp += 1;
len -= 1;
ND_PRINT("flags [%s], ",
bittok2str_nosep(vxlan_gpe_flags, "none", flags));
/* Reserved */
bp += 2;
len -= 2;
next_protocol = GET_U_1(bp);
bp += 1;
len -= 1;
vni = GET_BE_U_3(bp);
bp += 3;
len -= 3;
/* Reserved */
ND_TCHECK_1(bp);
bp += 1;
len -= 1;
ND_PRINT("vni %u", vni);
ND_PRINT(ndo->ndo_vflag ? "\n " : ": ");
switch (next_protocol) {
case 0x1:
ip_print(ndo, bp, len);
break;
case 0x2:
ip6_print(ndo, bp, len);
break;
case 0x3:
ether_print(ndo, bp, len, ND_BYTES_AVAILABLE_AFTER(bp), NULL, NULL);
break;
case 0x4:
nsh_print(ndo, bp, len);
break;
default:
ND_PRINT("ERROR: unknown-next-protocol");
goto invalid;
}
return;
invalid:
nd_print_invalid(ndo);
}