414 lines
11 KiB
C
414 lines
11 KiB
C
/*
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* This module implements decoding of AHCP (Ad Hoc Configuration Protocol) based
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* on draft-chroboczek-ahcp-00 and source code of ahcpd-0.53.
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*
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*
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* Copyright (c) 2013 The TCPDUMP project
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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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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* 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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#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 "interface.h"
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#include "extract.h"
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#include "addrtoname.h"
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static const char tstr[] = " [|ahcp]";
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static const char cstr[] = "(corrupt)";
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#define AHCP_MAGIC_NUMBER 43
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#define AHCP_VERSION_1 1
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#define AHCP1_HEADER_FIX_LEN 24
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#define AHCP1_BODY_MIN_LEN 4
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#define AHCP1_MSG_DISCOVER 0
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#define AHCP1_MSG_OFFER 1
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#define AHCP1_MSG_REQUEST 2
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#define AHCP1_MSG_ACK 3
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#define AHCP1_MSG_NACK 4
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#define AHCP1_MSG_RELEASE 5
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static const struct tok ahcp1_msg_str[] = {
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{ AHCP1_MSG_DISCOVER, "Discover" },
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{ AHCP1_MSG_OFFER, "Offer" },
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{ AHCP1_MSG_REQUEST, "Request" },
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{ AHCP1_MSG_ACK, "Ack" },
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{ AHCP1_MSG_NACK, "Nack" },
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{ AHCP1_MSG_RELEASE, "Release" },
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{ 0, NULL }
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};
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#define AHCP1_OPT_PAD 0
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#define AHCP1_OPT_MANDATORY 1
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#define AHCP1_OPT_ORIGIN_TIME 2
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#define AHCP1_OPT_EXPIRES 3
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#define AHCP1_OPT_MY_IPV6_ADDRESS 4
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#define AHCP1_OPT_MY_IPV4_ADDRESS 5
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#define AHCP1_OPT_IPV6_PREFIX 6
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#define AHCP1_OPT_IPV4_PREFIX 7
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#define AHCP1_OPT_IPV6_ADDRESS 8
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#define AHCP1_OPT_IPV4_ADDRESS 9
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#define AHCP1_OPT_IPV6_PREFIX_DELEGATION 10
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#define AHCP1_OPT_IPV4_PREFIX_DELEGATION 11
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#define AHCP1_OPT_NAME_SERVER 12
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#define AHCP1_OPT_NTP_SERVER 13
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#define AHCP1_OPT_MAX 13
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static const struct tok ahcp1_opt_str[] = {
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{ AHCP1_OPT_PAD, "Pad" },
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{ AHCP1_OPT_MANDATORY, "Mandatory" },
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{ AHCP1_OPT_ORIGIN_TIME, "Origin Time" },
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{ AHCP1_OPT_EXPIRES, "Expires" },
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{ AHCP1_OPT_MY_IPV6_ADDRESS, "My-IPv6-Address" },
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{ AHCP1_OPT_MY_IPV4_ADDRESS, "My-IPv4-Address" },
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{ AHCP1_OPT_IPV6_PREFIX, "IPv6 Prefix" },
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{ AHCP1_OPT_IPV4_PREFIX, "IPv4 Prefix" },
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{ AHCP1_OPT_IPV6_ADDRESS, "IPv6 Address" },
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{ AHCP1_OPT_IPV4_ADDRESS, "IPv4 Address" },
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{ AHCP1_OPT_IPV6_PREFIX_DELEGATION, "IPv6 Prefix Delegation" },
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{ AHCP1_OPT_IPV4_PREFIX_DELEGATION, "IPv4 Prefix Delegation" },
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{ AHCP1_OPT_NAME_SERVER, "Name Server" },
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{ AHCP1_OPT_NTP_SERVER, "NTP Server" },
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{ 0, NULL }
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};
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static int
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ahcp_time_print(netdissect_options *ndo, const u_char *cp, const u_char *ep) {
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time_t t;
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struct tm *tm;
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char buf[BUFSIZE];
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if (cp + 4 != ep)
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goto corrupt;
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ND_TCHECK2(*cp, 4);
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t = EXTRACT_32BITS(cp);
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if (NULL == (tm = gmtime(&t)))
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ND_PRINT((ndo, ": gmtime() error"));
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else if (0 == strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", tm))
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ND_PRINT((ndo, ": strftime() error"));
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else
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ND_PRINT((ndo, ": %s UTC", buf));
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return 0;
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corrupt:
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ND_PRINT((ndo, ": %s", cstr));
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ND_TCHECK2(*cp, ep - cp);
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return 0;
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trunc:
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ND_PRINT((ndo, "%s", tstr));
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return -1;
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}
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static int
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ahcp_seconds_print(netdissect_options *ndo, const u_char *cp, const u_char *ep) {
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if (cp + 4 != ep)
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goto corrupt;
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ND_TCHECK2(*cp, 4);
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ND_PRINT((ndo, ": %us", EXTRACT_32BITS(cp)));
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return 0;
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corrupt:
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ND_PRINT((ndo, ": %s", cstr));
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ND_TCHECK2(*cp, ep - cp);
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return 0;
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trunc:
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ND_PRINT((ndo, "%s", tstr));
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return -1;
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}
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static int
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ahcp_ipv6_addresses_print(netdissect_options *ndo, const u_char *cp, const u_char *ep) {
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const char *sep = ": ";
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while (cp < ep) {
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if (cp + 16 > ep)
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goto corrupt;
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ND_TCHECK2(*cp, 16);
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#ifdef INET6
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ND_PRINT((ndo, "%s%s", sep, ip6addr_string(ndo, cp)));
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#else
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ND_PRINT((ndo, "%s(compiled w/o IPv6)", sep));
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#endif /* INET6 */
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cp += 16;
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sep = ", ";
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}
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return 0;
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corrupt:
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ND_PRINT((ndo, ": %s", cstr));
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ND_TCHECK2(*cp, ep - cp);
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return 0;
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trunc:
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ND_PRINT((ndo, "%s", tstr));
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return -1;
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}
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static int
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ahcp_ipv4_addresses_print(netdissect_options *ndo, const u_char *cp, const u_char *ep) {
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const char *sep = ": ";
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while (cp < ep) {
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if (cp + 4 > ep)
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goto corrupt;
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ND_TCHECK2(*cp, 4);
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ND_PRINT((ndo, "%s%s", sep, ipaddr_string(ndo, cp)));
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cp += 4;
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sep = ", ";
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}
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return 0;
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corrupt:
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ND_PRINT((ndo, ": %s", cstr));
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ND_TCHECK2(*cp, ep - cp);
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return 0;
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trunc:
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ND_PRINT((ndo, "%s", tstr));
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return -1;
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}
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static int
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ahcp_ipv6_prefixes_print(netdissect_options *ndo, const u_char *cp, const u_char *ep) {
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const char *sep = ": ";
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while (cp < ep) {
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if (cp + 17 > ep)
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goto corrupt;
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ND_TCHECK2(*cp, 17);
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#ifdef INET6
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ND_PRINT((ndo, "%s%s/%u", sep, ip6addr_string(ndo, cp), *(cp + 16)));
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#else
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ND_PRINT((ndo, "%s(compiled w/o IPv6)/%u", sep, *(cp + 16)));
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#endif /* INET6 */
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cp += 17;
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sep = ", ";
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}
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return 0;
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corrupt:
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ND_PRINT((ndo, ": %s", cstr));
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ND_TCHECK2(*cp, ep - cp);
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return 0;
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trunc:
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ND_PRINT((ndo, "%s", tstr));
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return -1;
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}
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static int
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ahcp_ipv4_prefixes_print(netdissect_options *ndo, const u_char *cp, const u_char *ep) {
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const char *sep = ": ";
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while (cp < ep) {
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if (cp + 5 > ep)
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goto corrupt;
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ND_TCHECK2(*cp, 5);
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ND_PRINT((ndo, "%s%s/%u", sep, ipaddr_string(ndo, cp), *(cp + 4)));
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cp += 5;
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sep = ", ";
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}
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return 0;
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corrupt:
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ND_PRINT((ndo, ": %s", cstr));
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ND_TCHECK2(*cp, ep - cp);
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return 0;
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trunc:
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ND_PRINT((ndo, "%s", tstr));
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return -1;
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}
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/* Data decoders signal truncated data with -1. */
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static int
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(* const data_decoders[AHCP1_OPT_MAX + 1])(netdissect_options *, const u_char *, const u_char *) = {
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/* [AHCP1_OPT_PAD] = */ NULL,
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/* [AHCP1_OPT_MANDATORY] = */ NULL,
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/* [AHCP1_OPT_ORIGIN_TIME] = */ ahcp_time_print,
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/* [AHCP1_OPT_EXPIRES] = */ ahcp_seconds_print,
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/* [AHCP1_OPT_MY_IPV6_ADDRESS] = */ ahcp_ipv6_addresses_print,
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/* [AHCP1_OPT_MY_IPV4_ADDRESS] = */ ahcp_ipv4_addresses_print,
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/* [AHCP1_OPT_IPV6_PREFIX] = */ ahcp_ipv6_prefixes_print,
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/* [AHCP1_OPT_IPV4_PREFIX] = */ NULL,
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/* [AHCP1_OPT_IPV6_ADDRESS] = */ ahcp_ipv6_addresses_print,
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/* [AHCP1_OPT_IPV4_ADDRESS] = */ ahcp_ipv4_addresses_print,
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/* [AHCP1_OPT_IPV6_PREFIX_DELEGATION] = */ ahcp_ipv6_prefixes_print,
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/* [AHCP1_OPT_IPV4_PREFIX_DELEGATION] = */ ahcp_ipv4_prefixes_print,
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/* [AHCP1_OPT_NAME_SERVER] = */ ahcp_ipv6_addresses_print,
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/* [AHCP1_OPT_NTP_SERVER] = */ ahcp_ipv6_addresses_print,
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};
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static void
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ahcp1_options_print(netdissect_options *ndo, const u_char *cp, const u_char *ep) {
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uint8_t option_no, option_len;
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while (cp < ep) {
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/* Option no */
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ND_TCHECK2(*cp, 1);
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option_no = *cp;
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cp += 1;
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ND_PRINT((ndo, "\n\t %s", tok2str(ahcp1_opt_str, "Unknown-%u", option_no)));
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if (option_no == AHCP1_OPT_PAD || option_no == AHCP1_OPT_MANDATORY)
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continue;
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/* Length */
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if (cp + 1 > ep)
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goto corrupt;
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ND_TCHECK2(*cp, 1);
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option_len = *cp;
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cp += 1;
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if (cp + option_len > ep)
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goto corrupt;
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/* Value */
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if (option_no <= AHCP1_OPT_MAX && data_decoders[option_no] != NULL) {
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if (data_decoders[option_no](ndo, cp, cp + option_len) < 0)
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break; /* truncated and already marked up */
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} else {
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ND_PRINT((ndo, " (Length %u)", option_len));
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ND_TCHECK2(*cp, option_len);
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}
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cp += option_len;
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}
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return;
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corrupt:
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ND_PRINT((ndo, " %s", cstr));
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ND_TCHECK2(*cp, ep - cp);
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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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ahcp1_body_print(netdissect_options *ndo, const u_char *cp, const u_char *ep) {
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uint8_t type, mbz;
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uint16_t body_len;
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if (cp + AHCP1_BODY_MIN_LEN > ep)
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goto corrupt;
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/* Type */
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ND_TCHECK2(*cp, 1);
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type = *cp;
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cp += 1;
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/* MBZ */
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ND_TCHECK2(*cp, 1);
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mbz = *cp;
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cp += 1;
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/* Length */
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ND_TCHECK2(*cp, 2);
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body_len = EXTRACT_16BITS(cp);
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cp += 2;
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if (ndo->ndo_vflag) {
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ND_PRINT((ndo, "\n\t%s", tok2str(ahcp1_msg_str, "Unknown-%u", type)));
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if (mbz != 0)
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ND_PRINT((ndo, ", MBZ %u", mbz));
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ND_PRINT((ndo, ", Length %u", body_len));
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}
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if (cp + body_len > ep)
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goto corrupt;
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/* Options */
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if (ndo->ndo_vflag >= 2)
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ahcp1_options_print(ndo, cp, cp + body_len); /* not ep (ignore extra data) */
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else
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ND_TCHECK2(*cp, body_len);
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return;
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corrupt:
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ND_PRINT((ndo, " %s", cstr));
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ND_TCHECK2(*cp, ep - cp);
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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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void
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ahcp_print(netdissect_options *ndo, const u_char *cp, const u_int len) {
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const u_char *ep = cp + len;
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uint8_t version;
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ND_PRINT((ndo, "AHCP"));
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if (len < 2)
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goto corrupt;
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/* Magic */
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ND_TCHECK2(*cp, 1);
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if (*cp != AHCP_MAGIC_NUMBER)
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goto corrupt;
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cp += 1;
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/* Version */
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ND_TCHECK2(*cp, 1);
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version = *cp;
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cp += 1;
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switch (version) {
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case AHCP_VERSION_1: {
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ND_PRINT((ndo, " Version 1"));
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if (len < AHCP1_HEADER_FIX_LEN)
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goto corrupt;
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if (!ndo->ndo_vflag) {
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ND_TCHECK2(*cp, AHCP1_HEADER_FIX_LEN - 2);
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cp += AHCP1_HEADER_FIX_LEN - 2;
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} else {
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/* Hopcount */
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ND_TCHECK2(*cp, 1);
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ND_PRINT((ndo, "\n\tHopcount %u", *cp));
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cp += 1;
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/* Original Hopcount */
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ND_TCHECK2(*cp, 1);
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ND_PRINT((ndo, ", Original Hopcount %u", *cp));
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cp += 1;
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/* Nonce */
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ND_TCHECK2(*cp, 4);
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ND_PRINT((ndo, ", Nonce 0x%08x", EXTRACT_32BITS(cp)));
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cp += 4;
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/* Source Id */
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ND_TCHECK2(*cp, 8);
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ND_PRINT((ndo, ", Source Id %s", linkaddr_string(ndo, cp, 0, 8)));
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cp += 8;
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/* Destination Id */
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ND_TCHECK2(*cp, 8);
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ND_PRINT((ndo, ", Destination Id %s", linkaddr_string(ndo, cp, 0, 8)));
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cp += 8;
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}
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/* Body */
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ahcp1_body_print(ndo, cp, ep);
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break;
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}
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default:
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ND_PRINT((ndo, " Version %u (unknown)", version));
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break;
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}
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return;
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corrupt:
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ND_PRINT((ndo, " %s", cstr));
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ND_TCHECK2(*cp, ep - cp);
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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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