nexmon – Rev 1
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/*
* This module implements decoding of AHCP (Ad Hoc Configuration Protocol) based
* on draft-chroboczek-ahcp-00 and source code of ahcpd-0.53.
*
*
* Copyright (c) 2013 The TCPDUMP project
* 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 HOLDER 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.
*/
#define NETDISSECT_REWORKED
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <tcpdump-stdinc.h>
#include "interface.h"
#include "extract.h"
#include "addrtoname.h"
static const char tstr[] = " [|ahcp]";
static const char cstr[] = "(corrupt)";
#define AHCP_MAGIC_NUMBER 43
#define AHCP_VERSION_1 1
#define AHCP1_HEADER_FIX_LEN 24
#define AHCP1_BODY_MIN_LEN 4
#define AHCP1_MSG_DISCOVER 0
#define AHCP1_MSG_OFFER 1
#define AHCP1_MSG_REQUEST 2
#define AHCP1_MSG_ACK 3
#define AHCP1_MSG_NACK 4
#define AHCP1_MSG_RELEASE 5
static const struct tok ahcp1_msg_str[] = {
{ AHCP1_MSG_DISCOVER, "Discover" },
{ AHCP1_MSG_OFFER, "Offer" },
{ AHCP1_MSG_REQUEST, "Request" },
{ AHCP1_MSG_ACK, "Ack" },
{ AHCP1_MSG_NACK, "Nack" },
{ AHCP1_MSG_RELEASE, "Release" },
{ 0, NULL }
};
#define AHCP1_OPT_PAD 0
#define AHCP1_OPT_MANDATORY 1
#define AHCP1_OPT_ORIGIN_TIME 2
#define AHCP1_OPT_EXPIRES 3
#define AHCP1_OPT_MY_IPV6_ADDRESS 4
#define AHCP1_OPT_MY_IPV4_ADDRESS 5
#define AHCP1_OPT_IPV6_PREFIX 6
#define AHCP1_OPT_IPV4_PREFIX 7
#define AHCP1_OPT_IPV6_ADDRESS 8
#define AHCP1_OPT_IPV4_ADDRESS 9
#define AHCP1_OPT_IPV6_PREFIX_DELEGATION 10
#define AHCP1_OPT_IPV4_PREFIX_DELEGATION 11
#define AHCP1_OPT_NAME_SERVER 12
#define AHCP1_OPT_NTP_SERVER 13
#define AHCP1_OPT_MAX 13
static const struct tok ahcp1_opt_str[] = {
{ AHCP1_OPT_PAD, "Pad" },
{ AHCP1_OPT_MANDATORY, "Mandatory" },
{ AHCP1_OPT_ORIGIN_TIME, "Origin Time" },
{ AHCP1_OPT_EXPIRES, "Expires" },
{ AHCP1_OPT_MY_IPV6_ADDRESS, "My-IPv6-Address" },
{ AHCP1_OPT_MY_IPV4_ADDRESS, "My-IPv4-Address" },
{ AHCP1_OPT_IPV6_PREFIX, "IPv6 Prefix" },
{ AHCP1_OPT_IPV4_PREFIX, "IPv4 Prefix" },
{ AHCP1_OPT_IPV6_ADDRESS, "IPv6 Address" },
{ AHCP1_OPT_IPV4_ADDRESS, "IPv4 Address" },
{ AHCP1_OPT_IPV6_PREFIX_DELEGATION, "IPv6 Prefix Delegation" },
{ AHCP1_OPT_IPV4_PREFIX_DELEGATION, "IPv4 Prefix Delegation" },
{ AHCP1_OPT_NAME_SERVER, "Name Server" },
{ AHCP1_OPT_NTP_SERVER, "NTP Server" },
{ 0, NULL }
};
static int
ahcp_time_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
{
time_t t;
struct tm *tm;
char buf[BUFSIZE];
if (cp + 4 != ep)
goto corrupt;
ND_TCHECK2(*cp, 4);
t = EXTRACT_32BITS(cp);
if (NULL == (tm = gmtime(&t)))
ND_PRINT((ndo, ": gmtime() error"));
else if (0 == strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", tm))
ND_PRINT((ndo, ": strftime() error"));
else
ND_PRINT((ndo, ": %s UTC", buf));
return 0;
corrupt:
ND_PRINT((ndo, ": %s", cstr));
ND_TCHECK2(*cp, ep - cp);
return 0;
trunc:
ND_PRINT((ndo, "%s", tstr));
return -1;
}
static int
ahcp_seconds_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
{
if (cp + 4 != ep)
goto corrupt;
ND_TCHECK2(*cp, 4);
ND_PRINT((ndo, ": %us", EXTRACT_32BITS(cp)));
return 0;
corrupt:
ND_PRINT((ndo, ": %s", cstr));
ND_TCHECK2(*cp, ep - cp);
return 0;
trunc:
ND_PRINT((ndo, "%s", tstr));
return -1;
}
static int
ahcp_ipv6_addresses_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
{
const char *sep = ": ";
while (cp < ep) {
if (cp + 16 > ep)
goto corrupt;
ND_TCHECK2(*cp, 16);
#ifdef INET6
ND_PRINT((ndo, "%s%s", sep, ip6addr_string(ndo, cp)));
#else
ND_PRINT((ndo, "%s(compiled w/o IPv6)", sep));
#endif /* INET6 */
cp += 16;
sep = ", ";
}
return 0;
corrupt:
ND_PRINT((ndo, ": %s", cstr));
ND_TCHECK2(*cp, ep - cp);
return 0;
trunc:
ND_PRINT((ndo, "%s", tstr));
return -1;
}
static int
ahcp_ipv4_addresses_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
{
const char *sep = ": ";
while (cp < ep) {
if (cp + 4 > ep)
goto corrupt;
ND_TCHECK2(*cp, 4);
ND_PRINT((ndo, "%s%s", sep, ipaddr_string(ndo, cp)));
cp += 4;
sep = ", ";
}
return 0;
corrupt:
ND_PRINT((ndo, ": %s", cstr));
ND_TCHECK2(*cp, ep - cp);
return 0;
trunc:
ND_PRINT((ndo, "%s", tstr));
return -1;
}
static int
ahcp_ipv6_prefixes_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
{
const char *sep = ": ";
while (cp < ep) {
if (cp + 17 > ep)
goto corrupt;
ND_TCHECK2(*cp, 17);
#ifdef INET6
ND_PRINT((ndo, "%s%s/%u", sep, ip6addr_string(ndo, cp), *(cp + 16)));
#else
ND_PRINT((ndo, "%s(compiled w/o IPv6)/%u", sep, *(cp + 16)));
#endif /* INET6 */
cp += 17;
sep = ", ";
}
return 0;
corrupt:
ND_PRINT((ndo, ": %s", cstr));
ND_TCHECK2(*cp, ep - cp);
return 0;
trunc:
ND_PRINT((ndo, "%s", tstr));
return -1;
}
static int
ahcp_ipv4_prefixes_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
{
const char *sep = ": ";
while (cp < ep) {
if (cp + 5 > ep)
goto corrupt;
ND_TCHECK2(*cp, 5);
ND_PRINT((ndo, "%s%s/%u", sep, ipaddr_string(ndo, cp), *(cp + 4)));
cp += 5;
sep = ", ";
}
return 0;
corrupt:
ND_PRINT((ndo, ": %s", cstr));
ND_TCHECK2(*cp, ep - cp);
return 0;
trunc:
ND_PRINT((ndo, "%s", tstr));
return -1;
}
/* Data decoders signal truncated data with -1. */
static int
(* const data_decoders[AHCP1_OPT_MAX + 1])(netdissect_options *, const u_char *, const u_char *) = {
/* [AHCP1_OPT_PAD] = */ NULL,
/* [AHCP1_OPT_MANDATORY] = */ NULL,
/* [AHCP1_OPT_ORIGIN_TIME] = */ ahcp_time_print,
/* [AHCP1_OPT_EXPIRES] = */ ahcp_seconds_print,
/* [AHCP1_OPT_MY_IPV6_ADDRESS] = */ ahcp_ipv6_addresses_print,
/* [AHCP1_OPT_MY_IPV4_ADDRESS] = */ ahcp_ipv4_addresses_print,
/* [AHCP1_OPT_IPV6_PREFIX] = */ ahcp_ipv6_prefixes_print,
/* [AHCP1_OPT_IPV4_PREFIX] = */ NULL,
/* [AHCP1_OPT_IPV6_ADDRESS] = */ ahcp_ipv6_addresses_print,
/* [AHCP1_OPT_IPV4_ADDRESS] = */ ahcp_ipv4_addresses_print,
/* [AHCP1_OPT_IPV6_PREFIX_DELEGATION] = */ ahcp_ipv6_prefixes_print,
/* [AHCP1_OPT_IPV4_PREFIX_DELEGATION] = */ ahcp_ipv4_prefixes_print,
/* [AHCP1_OPT_NAME_SERVER] = */ ahcp_ipv6_addresses_print,
/* [AHCP1_OPT_NTP_SERVER] = */ ahcp_ipv6_addresses_print,
};
static void
ahcp1_options_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
{
uint8_t option_no, option_len;
while (cp < ep) {
/* Option no */
ND_TCHECK2(*cp, 1);
option_no = *cp;
cp += 1;
ND_PRINT((ndo, "\n\t %s", tok2str(ahcp1_opt_str, "Unknown-%u", option_no)));
if (option_no == AHCP1_OPT_PAD || option_no == AHCP1_OPT_MANDATORY)
continue;
/* Length */
if (cp + 1 > ep)
goto corrupt;
ND_TCHECK2(*cp, 1);
option_len = *cp;
cp += 1;
if (cp + option_len > ep)
goto corrupt;
/* Value */
if (option_no <= AHCP1_OPT_MAX && data_decoders[option_no] != NULL) {
if (data_decoders[option_no](ndo, cp, cp + option_len) < 0)
break; /* truncated and already marked up */
} else {
ND_PRINT((ndo, " (Length %u)", option_len));
ND_TCHECK2(*cp, option_len);
}
cp += option_len;
}
return;
corrupt:
ND_PRINT((ndo, " %s", cstr));
ND_TCHECK2(*cp, ep - cp);
return;
trunc:
ND_PRINT((ndo, "%s", tstr));
}
static void
ahcp1_body_print(netdissect_options *ndo, const u_char *cp, const u_char *ep)
{
uint8_t type, mbz;
uint16_t body_len;
if (cp + AHCP1_BODY_MIN_LEN > ep)
goto corrupt;
/* Type */
ND_TCHECK2(*cp, 1);
type = *cp;
cp += 1;
/* MBZ */
ND_TCHECK2(*cp, 1);
mbz = *cp;
cp += 1;
/* Length */
ND_TCHECK2(*cp, 2);
body_len = EXTRACT_16BITS(cp);
cp += 2;
if (ndo->ndo_vflag) {
ND_PRINT((ndo, "\n\t%s", tok2str(ahcp1_msg_str, "Unknown-%u", type)));
if (mbz != 0)
ND_PRINT((ndo, ", MBZ %u", mbz));
ND_PRINT((ndo, ", Length %u", body_len));
}
if (cp + body_len > ep)
goto corrupt;
/* Options */
if (ndo->ndo_vflag >= 2)
ahcp1_options_print(ndo, cp, cp + body_len); /* not ep (ignore extra data) */
else
ND_TCHECK2(*cp, body_len);
return;
corrupt:
ND_PRINT((ndo, " %s", cstr));
ND_TCHECK2(*cp, ep - cp);
return;
trunc:
ND_PRINT((ndo, "%s", tstr));
}
void
ahcp_print(netdissect_options *ndo, const u_char *cp, const u_int len)
{
const u_char *ep = cp + len;
uint8_t version;
ND_PRINT((ndo, "AHCP"));
if (len < 2)
goto corrupt;
/* Magic */
ND_TCHECK2(*cp, 1);
if (*cp != AHCP_MAGIC_NUMBER)
goto corrupt;
cp += 1;
/* Version */
ND_TCHECK2(*cp, 1);
version = *cp;
cp += 1;
switch (version) {
case AHCP_VERSION_1: {
ND_PRINT((ndo, " Version 1"));
if (len < AHCP1_HEADER_FIX_LEN)
goto corrupt;
if (!ndo->ndo_vflag) {
ND_TCHECK2(*cp, AHCP1_HEADER_FIX_LEN - 2);
cp += AHCP1_HEADER_FIX_LEN - 2;
} else {
/* Hopcount */
ND_TCHECK2(*cp, 1);
ND_PRINT((ndo, "\n\tHopcount %u", *cp));
cp += 1;
/* Original Hopcount */
ND_TCHECK2(*cp, 1);
ND_PRINT((ndo, ", Original Hopcount %u", *cp));
cp += 1;
/* Nonce */
ND_TCHECK2(*cp, 4);
ND_PRINT((ndo, ", Nonce 0x%08x", EXTRACT_32BITS(cp)));
cp += 4;
/* Source Id */
ND_TCHECK2(*cp, 8);
ND_PRINT((ndo, ", Source Id %s", linkaddr_string(ndo, cp, 0, 8)));
cp += 8;
/* Destination Id */
ND_TCHECK2(*cp, 8);
ND_PRINT((ndo, ", Destination Id %s", linkaddr_string(ndo, cp, 0, 8)));
cp += 8;
}
/* Body */
ahcp1_body_print(ndo, cp, ep);
break;
}
default:
ND_PRINT((ndo, " Version %u (unknown)", version));
break;
}
return;
corrupt:
ND_PRINT((ndo, " %s", cstr));
ND_TCHECK2(*cp, ep - cp);
return;
trunc:
ND_PRINT((ndo, "%s", tstr));
}