nexmon – Rev 1

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/*
 * Copyright (c) 1990, 1991, 1993, 1994, 1995, 1996, 1997
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that: (1) source code distributions
 * retain the above copyright notice and this paragraph in its entirety, (2)
 * distributions including binary code include the above copyright notice and
 * this paragraph in its entirety in the documentation or other materials
 * provided with the distribution, and (3) all advertising materials mentioning
 * features or use of this software display the following acknowledgement:
 * ``This product includes software developed by the University of California,
 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
 * the University nor the names of its contributors may be used to endorse
 * or promote products derived from this software without specific prior
 * written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Extensively modified by Motonori Shindo (mshindo@mshindo.net) for more
 * complete PPP support.
 */

/*
 * TODO:
 * o resolve XXX as much as possible
 * o MP support
 * o BAP support
 */

#define NETDISSECT_REWORKED
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <tcpdump-stdinc.h>

#ifdef __bsdi__
#include <net/slcompress.h>
#include <net/if_ppp.h>
#endif

#include <stdlib.h>

#include "interface.h"
#include "extract.h"
#include "addrtoname.h"
#include "ppp.h"
#include "chdlc.h"
#include "ethertype.h"
#include "oui.h"

/*
 * The following constatns are defined by IANA. Please refer to
 *    http://www.isi.edu/in-notes/iana/assignments/ppp-numbers
 * for the up-to-date information.
 */

/* Protocol Codes defined in ppp.h */

static const struct tok ppptype2str[] = {
        { PPP_IP,         "IP" },
        { PPP_OSI,        "OSI" },
        { PPP_NS,         "NS" },
        { PPP_DECNET,     "DECNET" },
        { PPP_APPLE,      "APPLE" },
        { PPP_IPX,        "IPX" },
        { PPP_VJC,        "VJC IP" },
        { PPP_VJNC,       "VJNC IP" },
        { PPP_BRPDU,      "BRPDU" },
        { PPP_STII,       "STII" },
        { PPP_VINES,      "VINES" },
        { PPP_MPLS_UCAST, "MPLS" },
        { PPP_MPLS_MCAST, "MPLS" },
        { PPP_COMP,       "Compressed"},
        { PPP_ML,         "MLPPP"},
        { PPP_IPV6,       "IP6"},

        { PPP_HELLO,      "HELLO" },
        { PPP_LUXCOM,     "LUXCOM" },
        { PPP_SNS,        "SNS" },
        { PPP_IPCP,       "IPCP" },
        { PPP_OSICP,      "OSICP" },
        { PPP_NSCP,       "NSCP" },
        { PPP_DECNETCP,   "DECNETCP" },
        { PPP_APPLECP,    "APPLECP" },
        { PPP_IPXCP,      "IPXCP" },
        { PPP_STIICP,     "STIICP" },
        { PPP_VINESCP,    "VINESCP" },
        { PPP_IPV6CP,     "IP6CP" },
        { PPP_MPLSCP,     "MPLSCP" },

        { PPP_LCP,        "LCP" },
        { PPP_PAP,        "PAP" },
        { PPP_LQM,        "LQM" },
        { PPP_CHAP,       "CHAP" },
        { PPP_EAP,        "EAP" },
        { PPP_SPAP,       "SPAP" },
        { PPP_SPAP_OLD,   "Old-SPAP" },
        { PPP_BACP,       "BACP" },
        { PPP_BAP,        "BAP" },
        { PPP_MPCP,       "MLPPP-CP" },
        { PPP_CCP,        "CCP" },
        { 0,              NULL }
};

/* Control Protocols (LCP/IPCP/CCP etc.) Codes defined in RFC 1661 */

#define CPCODES_VEXT            0        /* Vendor-Specific (RFC2153) */
#define CPCODES_CONF_REQ        1       /* Configure-Request */
#define CPCODES_CONF_ACK        2       /* Configure-Ack */
#define CPCODES_CONF_NAK        3       /* Configure-Nak */
#define CPCODES_CONF_REJ        4       /* Configure-Reject */
#define CPCODES_TERM_REQ        5       /* Terminate-Request */
#define CPCODES_TERM_ACK        6       /* Terminate-Ack */
#define CPCODES_CODE_REJ        7       /* Code-Reject */
#define CPCODES_PROT_REJ        8       /* Protocol-Reject (LCP only) */
#define CPCODES_ECHO_REQ        9       /* Echo-Request (LCP only) */
#define CPCODES_ECHO_RPL        10      /* Echo-Reply (LCP only) */
#define CPCODES_DISC_REQ        11      /* Discard-Request (LCP only) */
#define CPCODES_ID              12      /* Identification (LCP only) RFC1570 */
#define CPCODES_TIME_REM        13      /* Time-Remaining (LCP only) RFC1570 */
#define CPCODES_RESET_REQ       14      /* Reset-Request (CCP only) RFC1962 */
#define CPCODES_RESET_REP       15      /* Reset-Reply (CCP only) */

static const struct tok cpcodes[] = {
        {CPCODES_VEXT,      "Vendor-Extension"}, /* RFC2153 */
        {CPCODES_CONF_REQ,  "Conf-Request"},
        {CPCODES_CONF_ACK,  "Conf-Ack"},
        {CPCODES_CONF_NAK,  "Conf-Nack"},
        {CPCODES_CONF_REJ,  "Conf-Reject"},
        {CPCODES_TERM_REQ,  "Term-Request"},
        {CPCODES_TERM_ACK,  "Term-Ack"},
        {CPCODES_CODE_REJ,  "Code-Reject"},
        {CPCODES_PROT_REJ,  "Prot-Reject"},
        {CPCODES_ECHO_REQ,  "Echo-Request"},
        {CPCODES_ECHO_RPL,  "Echo-Reply"},
        {CPCODES_DISC_REQ,  "Disc-Req"},
        {CPCODES_ID,        "Ident"},            /* RFC1570 */
        {CPCODES_TIME_REM,  "Time-Rem"},         /* RFC1570 */
        {CPCODES_RESET_REQ, "Reset-Req"},        /* RFC1962 */
        {CPCODES_RESET_REP, "Reset-Ack"},        /* RFC1962 */
        {0,                 NULL}
};

/* LCP Config Options */

#define LCPOPT_VEXT     0
#define LCPOPT_MRU      1
#define LCPOPT_ACCM     2
#define LCPOPT_AP       3
#define LCPOPT_QP       4
#define LCPOPT_MN       5
#define LCPOPT_DEP6     6
#define LCPOPT_PFC      7
#define LCPOPT_ACFC     8
#define LCPOPT_FCSALT   9
#define LCPOPT_SDP      10
#define LCPOPT_NUMMODE  11
#define LCPOPT_DEP12    12
#define LCPOPT_CBACK    13
#define LCPOPT_DEP14    14
#define LCPOPT_DEP15    15
#define LCPOPT_DEP16    16
#define LCPOPT_MLMRRU   17
#define LCPOPT_MLSSNHF  18
#define LCPOPT_MLED     19
#define LCPOPT_PROP     20
#define LCPOPT_DCEID    21
#define LCPOPT_MPP      22
#define LCPOPT_LD       23
#define LCPOPT_LCPAOPT  24
#define LCPOPT_COBS     25
#define LCPOPT_PE       26
#define LCPOPT_MLHF     27
#define LCPOPT_I18N     28
#define LCPOPT_SDLOS    29
#define LCPOPT_PPPMUX   30

#define LCPOPT_MIN LCPOPT_VEXT
#define LCPOPT_MAX LCPOPT_PPPMUX

static const char *lcpconfopts[] = {
        "Vend-Ext",             /* (0) */
        "MRU",                  /* (1) */
        "ACCM",                 /* (2) */
        "Auth-Prot",            /* (3) */
        "Qual-Prot",            /* (4) */
        "Magic-Num",            /* (5) */
        "deprecated(6)",        /* used to be a Quality Protocol */
        "PFC",                  /* (7) */
        "ACFC",                 /* (8) */
        "FCS-Alt",              /* (9) */
        "SDP",                  /* (10) */
        "Num-Mode",             /* (11) */
        "deprecated(12)",       /* used to be a Multi-Link-Procedure*/
        "Call-Back",            /* (13) */
        "deprecated(14)",       /* used to be a Connect-Time */
        "deprecated(15)",       /* used to be a Compund-Frames */
        "deprecated(16)",       /* used to be a Nominal-Data-Encap */
        "MRRU",                 /* (17) */
        "12-Bit seq #",         /* (18) */
        "End-Disc",             /* (19) */
        "Proprietary",          /* (20) */
        "DCE-Id",               /* (21) */
        "MP+",                  /* (22) */
        "Link-Disc",            /* (23) */
        "LCP-Auth-Opt",         /* (24) */
        "COBS",                 /* (25) */
        "Prefix-elision",       /* (26) */
        "Multilink-header-Form",/* (27) */
        "I18N",                 /* (28) */
        "SDL-over-SONET/SDH",   /* (29) */
        "PPP-Muxing",           /* (30) */
};

/* ECP - to be supported */

/* CCP Config Options */

#define CCPOPT_OUI      0        /* RFC1962 */
#define CCPOPT_PRED1    1       /* RFC1962 */
#define CCPOPT_PRED2    2       /* RFC1962 */
#define CCPOPT_PJUMP    3       /* RFC1962 */
/* 4-15 unassigned */
#define CCPOPT_HPPPC    16      /* RFC1962 */
#define CCPOPT_STACLZS  17      /* RFC1974 */
#define CCPOPT_MPPC     18      /* RFC2118 */
#define CCPOPT_GFZA     19      /* RFC1962 */
#define CCPOPT_V42BIS   20      /* RFC1962 */
#define CCPOPT_BSDCOMP  21      /* RFC1977 */
/* 22 unassigned */
#define CCPOPT_LZSDCP   23      /* RFC1967 */
#define CCPOPT_MVRCA    24      /* RFC1975 */
#define CCPOPT_DEC      25      /* RFC1976 */
#define CCPOPT_DEFLATE  26      /* RFC1979 */
/* 27-254 unassigned */
#define CCPOPT_RESV     255     /* RFC1962 */

static const struct tok ccpconfopts_values[] = {
        { CCPOPT_OUI, "OUI" },
        { CCPOPT_PRED1, "Pred-1" },
        { CCPOPT_PRED2, "Pred-2" },
        { CCPOPT_PJUMP, "Puddle" },
        { CCPOPT_HPPPC, "HP-PPC" },
        { CCPOPT_STACLZS, "Stac-LZS" },
        { CCPOPT_MPPC, "MPPC" },
        { CCPOPT_GFZA, "Gand-FZA" },
        { CCPOPT_V42BIS, "V.42bis" },
        { CCPOPT_BSDCOMP, "BSD-Comp" },
        { CCPOPT_LZSDCP, "LZS-DCP" },
        { CCPOPT_MVRCA, "MVRCA" },
        { CCPOPT_DEC, "DEC" },
        { CCPOPT_DEFLATE, "Deflate" },
        { CCPOPT_RESV, "Reserved"},
        {0,                 NULL}
};

/* BACP Config Options */

#define BACPOPT_FPEER   1       /* RFC2125 */

static const struct tok bacconfopts_values[] = {
        { BACPOPT_FPEER, "Favored-Peer" },
        {0,                 NULL}
};


/* SDCP - to be supported */

/* IPCP Config Options */
#define IPCPOPT_2ADDR   1       /* RFC1172, RFC1332 (deprecated) */
#define IPCPOPT_IPCOMP  2       /* RFC1332 */
#define IPCPOPT_ADDR    3       /* RFC1332 */
#define IPCPOPT_MOBILE4 4       /* RFC2290 */
#define IPCPOPT_PRIDNS  129     /* RFC1877 */
#define IPCPOPT_PRINBNS 130     /* RFC1877 */
#define IPCPOPT_SECDNS  131     /* RFC1877 */
#define IPCPOPT_SECNBNS 132     /* RFC1877 */

static const struct tok ipcpopt_values[] = {
        { IPCPOPT_2ADDR, "IP-Addrs" },
        { IPCPOPT_IPCOMP, "IP-Comp" },
        { IPCPOPT_ADDR, "IP-Addr" },
        { IPCPOPT_MOBILE4, "Home-Addr" },
        { IPCPOPT_PRIDNS, "Pri-DNS" },
        { IPCPOPT_PRINBNS, "Pri-NBNS" },
        { IPCPOPT_SECDNS, "Sec-DNS" },
        { IPCPOPT_SECNBNS, "Sec-NBNS" },
        { 0,              NULL }
};

#define IPCPOPT_IPCOMP_HDRCOMP 0x61  /* rfc3544 */
#define IPCPOPT_IPCOMP_MINLEN    14

static const struct tok ipcpopt_compproto_values[] = {
        { PPP_VJC, "VJ-Comp" },
        { IPCPOPT_IPCOMP_HDRCOMP, "IP Header Compression" },
        { 0,              NULL }
};

static const struct tok ipcpopt_compproto_subopt_values[] = {
        { 1, "RTP-Compression" },
        { 2, "Enhanced RTP-Compression" },
        { 0,              NULL }
};

/* IP6CP Config Options */
#define IP6CP_IFID      1

static const struct tok ip6cpopt_values[] = {
        { IP6CP_IFID, "Interface-ID" },
        { 0,              NULL }
};

/* ATCP - to be supported */
/* OSINLCP - to be supported */
/* BVCP - to be supported */
/* BCP - to be supported */
/* IPXCP - to be supported */
/* MPLSCP - to be supported */

/* Auth Algorithms */

/* 0-4 Reserved (RFC1994) */
#define AUTHALG_CHAPMD5 5       /* RFC1994 */
#define AUTHALG_MSCHAP1 128     /* RFC2433 */
#define AUTHALG_MSCHAP2 129     /* RFC2795 */

static const struct tok authalg_values[] = {
        { AUTHALG_CHAPMD5, "MD5" },
        { AUTHALG_MSCHAP1, "MS-CHAPv1" },
        { AUTHALG_MSCHAP2, "MS-CHAPv2" },
        { 0,              NULL }
};

/* FCS Alternatives - to be supported */

/* Multilink Endpoint Discriminator (RFC1717) */
#define MEDCLASS_NULL   0        /* Null Class */
#define MEDCLASS_LOCAL  1       /* Locally Assigned */
#define MEDCLASS_IPV4   2       /* Internet Protocol (IPv4) */
#define MEDCLASS_MAC    3       /* IEEE 802.1 global MAC address */
#define MEDCLASS_MNB    4       /* PPP Magic Number Block */
#define MEDCLASS_PSNDN  5       /* Public Switched Network Director Number */

/* PPP LCP Callback */
#define CALLBACK_AUTH   0        /* Location determined by user auth */
#define CALLBACK_DSTR   1       /* Dialing string */
#define CALLBACK_LID    2       /* Location identifier */
#define CALLBACK_E164   3       /* E.164 number */
#define CALLBACK_X500   4       /* X.500 distinguished name */
#define CALLBACK_CBCP   6       /* Location is determined during CBCP nego */

static const struct tok ppp_callback_values[] = {
        { CALLBACK_AUTH, "UserAuth" },
        { CALLBACK_DSTR, "DialString" },
        { CALLBACK_LID, "LocalID" },
        { CALLBACK_E164, "E.164" },
        { CALLBACK_X500, "X.500" },
        { CALLBACK_CBCP, "CBCP" },
        { 0,              NULL }
};

/* CHAP */

#define CHAP_CHAL       1
#define CHAP_RESP       2
#define CHAP_SUCC       3
#define CHAP_FAIL       4

static const struct tok chapcode_values[] = {
        { CHAP_CHAL, "Challenge" },
        { CHAP_RESP, "Response" },
        { CHAP_SUCC, "Success" },
        { CHAP_FAIL, "Fail" },
        { 0, NULL}
};

/* PAP */

#define PAP_AREQ        1
#define PAP_AACK        2
#define PAP_ANAK        3

static const struct tok papcode_values[] = {
        { PAP_AREQ, "Auth-Req" },
        { PAP_AACK, "Auth-ACK" },
        { PAP_ANAK, "Auth-NACK" },
        { 0, NULL }
};

/* BAP */
#define BAP_CALLREQ     1
#define BAP_CALLRES     2
#define BAP_CBREQ       3
#define BAP_CBRES       4
#define BAP_LDQREQ      5
#define BAP_LDQRES      6
#define BAP_CSIND       7
#define BAP_CSRES       8

static int print_lcp_config_options(netdissect_options *, const u_char *p, int);
static int print_ipcp_config_options(netdissect_options *, const u_char *p, int);
static int print_ip6cp_config_options(netdissect_options *, const u_char *p, int);
static int print_ccp_config_options(netdissect_options *, const u_char *p, int);
static int print_bacp_config_options(netdissect_options *, const u_char *p, int);
static void handle_ppp(netdissect_options *, u_int proto, const u_char *p, int length);

/* generic Control Protocol (e.g. LCP, IPCP, CCP, etc.) handler */
static void
handle_ctrl_proto(netdissect_options *ndo,
                  u_int proto, const u_char *pptr, int length)
{
        const char *typestr;
        u_int code, len;
        int (*pfunc)(netdissect_options *, const u_char *, int);
        int x, j;
        const u_char *tptr;

        tptr=pptr;

        typestr = tok2str(ppptype2str, "unknown ctrl-proto (0x%04x)", proto);
        ND_PRINT((ndo, "%s, ", typestr));

        if (length < 4) /* FIXME weak boundary checking */
                goto trunc;
        ND_TCHECK2(*tptr, 2);

        code = *tptr++;

        ND_PRINT((ndo, "%s (0x%02x), id %u, length %u",
                  tok2str(cpcodes, "Unknown Opcode",code),
                  code,
                  *tptr++, /* ID */
                  length + 2));

        if (!ndo->ndo_vflag)
                return;

        if (length <= 4)
                return;    /* there may be a NULL confreq etc. */

        ND_TCHECK2(*tptr, 2);
        len = EXTRACT_16BITS(tptr);
        tptr += 2;

        ND_PRINT((ndo, "\n\tencoded length %u (=Option(s) length %u)", len, len - 4));

        if (ndo->ndo_vflag > 1)
                print_unknown_data(ndo, pptr - 2, "\n\t", 6);


        switch (code) {
        case CPCODES_VEXT:
                if (length < 11)
                        break;
                ND_TCHECK2(*tptr, 4);
                ND_PRINT((ndo, "\n\t  Magic-Num 0x%08x", EXTRACT_32BITS(tptr)));
                tptr += 4;
                ND_TCHECK2(*tptr, 3);
                ND_PRINT((ndo, " Vendor: %s (%u)",
                       tok2str(oui_values,"Unknown",EXTRACT_24BITS(tptr)),
                       EXTRACT_24BITS(tptr)));
                /* XXX: need to decode Kind and Value(s)? */
                break;
        case CPCODES_CONF_REQ:
        case CPCODES_CONF_ACK:
        case CPCODES_CONF_NAK:
        case CPCODES_CONF_REJ:
                x = len - 4;    /* Code(1), Identifier(1) and Length(2) */
                do {
                        switch (proto) {
                        case PPP_LCP:
                                pfunc = print_lcp_config_options;
                                break;
                        case PPP_IPCP:
                                pfunc = print_ipcp_config_options;
                                break;
                        case PPP_IPV6CP:
                                pfunc = print_ip6cp_config_options;
                                break;
                        case PPP_CCP:
                                pfunc = print_ccp_config_options;
                                break;
                        case PPP_BACP:
                                pfunc = print_bacp_config_options;
                                break;
                        default:
                                /*
                                 * No print routine for the options for
                                 * this protocol.
                                 */
                                pfunc = NULL;
                                break;
                        }

                        if (pfunc == NULL) /* catch the above null pointer if unknown CP */
                                break;

                        if ((j = (*pfunc)(ndo, tptr, len)) == 0)
                                break;
                        x -= j;
                        tptr += j;
                } while (x > 0);
                break;

        case CPCODES_TERM_REQ:
        case CPCODES_TERM_ACK:
                /* XXX: need to decode Data? */
                break;
        case CPCODES_CODE_REJ:
                /* XXX: need to decode Rejected-Packet? */
                break;
        case CPCODES_PROT_REJ:
                if (length < 6)
                        break;
                ND_TCHECK2(*tptr, 2);
                ND_PRINT((ndo, "\n\t  Rejected %s Protocol (0x%04x)",
                       tok2str(ppptype2str,"unknown", EXTRACT_16BITS(tptr)),
                       EXTRACT_16BITS(tptr)));
                /* XXX: need to decode Rejected-Information? - hexdump for now */
                if (len > 6) {
                        ND_PRINT((ndo, "\n\t  Rejected Packet"));
                        print_unknown_data(ndo, tptr + 2, "\n\t    ", len - 2);
                }
                break;
        case CPCODES_ECHO_REQ:
        case CPCODES_ECHO_RPL:
        case CPCODES_DISC_REQ:
                if (length < 8)
                        break;
                ND_TCHECK2(*tptr, 4);
                ND_PRINT((ndo, "\n\t  Magic-Num 0x%08x", EXTRACT_32BITS(tptr)));
                /* XXX: need to decode Data? - hexdump for now */
                if (len > 8) {
                        ND_PRINT((ndo, "\n\t  -----trailing data-----"));
                        ND_TCHECK2(tptr[4], len - 8);
                        print_unknown_data(ndo, tptr + 4, "\n\t  ", len - 8);
                }
                break;
        case CPCODES_ID:
                if (length < 8)
                        break;
                ND_TCHECK2(*tptr, 4);
                ND_PRINT((ndo, "\n\t  Magic-Num 0x%08x", EXTRACT_32BITS(tptr)));
                /* RFC 1661 says this is intended to be human readable */
                if (len > 8) {
                        ND_PRINT((ndo, "\n\t  Message\n\t    "));
                        if (fn_printn(ndo, tptr + 4, len - 4, ndo->ndo_snapend))
                                goto trunc;
                }
                break;
        case CPCODES_TIME_REM:
                if (length < 12)
                        break;
                ND_TCHECK2(*tptr, 4);
                ND_PRINT((ndo, "\n\t  Magic-Num 0x%08x", EXTRACT_32BITS(tptr)));
                ND_TCHECK2(*(tptr + 4), 4);
                ND_PRINT((ndo, ", Seconds-Remaining %us", EXTRACT_32BITS(tptr + 4)));
                /* XXX: need to decode Message? */
                break;
        default:
                /* XXX this is dirty but we do not get the
                 * original pointer passed to the begin
                 * the PPP packet */
                if (ndo->ndo_vflag <= 1)
                        print_unknown_data(ndo, pptr - 2, "\n\t  ", length + 2);
                break;
        }
        return;

trunc:
        ND_PRINT((ndo, "[|%s]", typestr));
}

/* LCP config options */
static int
print_lcp_config_options(netdissect_options *ndo,
                         const u_char *p, int length)
{
        int len, opt;

        if (length < 2)
                return 0;
        ND_TCHECK2(*p, 2);
        len = p[1];
        opt = p[0];
        if (length < len)
                return 0;
        if (len < 2) {
                if ((opt >= LCPOPT_MIN) && (opt <= LCPOPT_MAX))
                        ND_PRINT((ndo, "\n\t  %s Option (0x%02x), length %u (length bogus, should be >= 2)",
                                  lcpconfopts[opt], opt, len));
                else
                        ND_PRINT((ndo, "\n\tunknown LCP option 0x%02x", opt));
                return 0;
        }
        if ((opt >= LCPOPT_MIN) && (opt <= LCPOPT_MAX))
                ND_PRINT((ndo, "\n\t  %s Option (0x%02x), length %u", lcpconfopts[opt], opt, len));
        else {
                ND_PRINT((ndo, "\n\tunknown LCP option 0x%02x", opt));
                return len;
        }

        switch (opt) {
        case LCPOPT_VEXT:
                if (len < 6) {
                        ND_PRINT((ndo, " (length bogus, should be >= 6)"));
                        return len;
                }
                ND_TCHECK2(*(p + 2), 3);
                ND_PRINT((ndo, ": Vendor: %s (%u)",
                        tok2str(oui_values,"Unknown",EXTRACT_24BITS(p+2)),
                        EXTRACT_24BITS(p + 2)));
#if 0
                ND_TCHECK(p[5]);
                ND_PRINT((ndo, ", kind: 0x%02x", p[5]));
                ND_PRINT((ndo, ", Value: 0x"));
                for (i = 0; i < len - 6; i++) {
                        ND_TCHECK(p[6 + i]);
                        ND_PRINT((ndo, "%02x", p[6 + i]));
                }
#endif
                break;
        case LCPOPT_MRU:
                if (len != 4) {
                        ND_PRINT((ndo, " (length bogus, should be = 4)"));
                        return len;
                }
                ND_TCHECK2(*(p + 2), 2);
                ND_PRINT((ndo, ": %u", EXTRACT_16BITS(p + 2)));
                break;
        case LCPOPT_ACCM:
                if (len != 6) {
                        ND_PRINT((ndo, " (length bogus, should be = 6)"));
                        return len;
                }
                ND_TCHECK2(*(p + 2), 4);
                ND_PRINT((ndo, ": 0x%08x", EXTRACT_32BITS(p + 2)));
                break;
        case LCPOPT_AP:
                if (len < 4) {
                        ND_PRINT((ndo, " (length bogus, should be >= 4)"));
                        return len;
                }
                ND_TCHECK2(*(p + 2), 2);
                ND_PRINT((ndo, ": %s", tok2str(ppptype2str, "Unknown Auth Proto (0x04x)", EXTRACT_16BITS(p + 2))));

                switch (EXTRACT_16BITS(p+2)) {
                case PPP_CHAP:
                        ND_TCHECK(p[4]);
                        ND_PRINT((ndo, ", %s", tok2str(authalg_values, "Unknown Auth Alg %u", p[4])));
                        break;
                case PPP_PAP: /* fall through */
                case PPP_EAP:
                case PPP_SPAP:
                case PPP_SPAP_OLD:
                        break;
                default:
                        print_unknown_data(ndo, p, "\n\t", len);
                }
                break;
        case LCPOPT_QP:
                if (len < 4) {
                        ND_PRINT((ndo, " (length bogus, should be >= 4)"));
                        return 0;
                }
                ND_TCHECK2(*(p + 2), 2);
                if (EXTRACT_16BITS(p+2) == PPP_LQM)
                        ND_PRINT((ndo, ": LQR"));
                else
                        ND_PRINT((ndo, ": unknown"));
                break;
        case LCPOPT_MN:
                if (len != 6) {
                        ND_PRINT((ndo, " (length bogus, should be = 6)"));
                        return 0;
                }
                ND_TCHECK2(*(p + 2), 4);
                ND_PRINT((ndo, ": 0x%08x", EXTRACT_32BITS(p + 2)));
                break;
        case LCPOPT_PFC:
                break;
        case LCPOPT_ACFC:
                break;
        case LCPOPT_LD:
                if (len != 4) {
                        ND_PRINT((ndo, " (length bogus, should be = 4)"));
                        return 0;
                }
                ND_TCHECK2(*(p + 2), 2);
                ND_PRINT((ndo, ": 0x%04x", EXTRACT_16BITS(p + 2)));
                break;
        case LCPOPT_CBACK:
                if (len < 3) {
                        ND_PRINT((ndo, " (length bogus, should be >= 3)"));
                        return 0;
                }
                ND_PRINT((ndo, ": "));
                ND_TCHECK(p[2]);
                ND_PRINT((ndo, ": Callback Operation %s (%u)",
                       tok2str(ppp_callback_values, "Unknown", p[2]),
                       p[2]));
                break;
        case LCPOPT_MLMRRU:
                if (len != 4) {
                        ND_PRINT((ndo, " (length bogus, should be = 4)"));
                        return 0;
                }
                ND_TCHECK2(*(p + 2), 2);
                ND_PRINT((ndo, ": %u", EXTRACT_16BITS(p + 2)));
                break;
        case LCPOPT_MLED:
                if (len < 3) {
                        ND_PRINT((ndo, " (length bogus, should be >= 3)"));
                        return 0;
                }
                ND_TCHECK(p[2]);
                switch (p[2]) {         /* class */
                case MEDCLASS_NULL:
                        ND_PRINT((ndo, ": Null"));
                        break;
                case MEDCLASS_LOCAL:
                        ND_PRINT((ndo, ": Local")); /* XXX */
                        break;
                case MEDCLASS_IPV4:
                        if (len != 7) {
                                ND_PRINT((ndo, " (length bogus, should be = 7)"));
                                return 0;
                        }
                        ND_TCHECK2(*(p + 3), 4);
                        ND_PRINT((ndo, ": IPv4 %s", ipaddr_string(ndo, p + 3)));
                        break;
                case MEDCLASS_MAC:
                        if (len != 9) {
                                ND_PRINT((ndo, " (length bogus, should be = 9)"));
                                return 0;
                        }
                        ND_TCHECK2(*(p + 3), 6);
                        ND_PRINT((ndo, ": MAC %s", etheraddr_string(ndo, p + 3)));
                        break;
                case MEDCLASS_MNB:
                        ND_PRINT((ndo, ": Magic-Num-Block")); /* XXX */
                        break;
                case MEDCLASS_PSNDN:
                        ND_PRINT((ndo, ": PSNDN")); /* XXX */
                        break;
                default:
                        ND_PRINT((ndo, ": Unknown class %u", p[2]));
                        break;
                }
                break;

/* XXX: to be supported */
#if 0
        case LCPOPT_DEP6:
        case LCPOPT_FCSALT:
        case LCPOPT_SDP:
        case LCPOPT_NUMMODE:
        case LCPOPT_DEP12:
        case LCPOPT_DEP14:
        case LCPOPT_DEP15:
        case LCPOPT_DEP16:
        case LCPOPT_MLSSNHF:
        case LCPOPT_PROP:
        case LCPOPT_DCEID:
        case LCPOPT_MPP:
        case LCPOPT_LCPAOPT:
        case LCPOPT_COBS:
        case LCPOPT_PE:
        case LCPOPT_MLHF:
        case LCPOPT_I18N:
        case LCPOPT_SDLOS:
        case LCPOPT_PPPMUX:
                break;
#endif
        default:
                /*
                 * Unknown option; dump it as raw bytes now if we're
                 * not going to do so below.
                 */
                if (ndo->ndo_vflag < 2)
                        print_unknown_data(ndo, &p[2], "\n\t    ", len - 2);
                break;
        }

        if (ndo->ndo_vflag > 1)
                print_unknown_data(ndo, &p[2], "\n\t    ", len - 2); /* exclude TLV header */

        return len;

trunc:
        ND_PRINT((ndo, "[|lcp]"));
        return 0;
}

/* ML-PPP*/
static const struct tok ppp_ml_flag_values[] = {
    { 0x80, "begin" },
    { 0x40, "end" },
    { 0, NULL }
};

static void
handle_mlppp(netdissect_options *ndo,
             const u_char *p, int length)
{
    if (!ndo->ndo_eflag)
        ND_PRINT((ndo, "MLPPP, "));

    ND_PRINT((ndo, "seq 0x%03x, Flags [%s], length %u",
           (EXTRACT_16BITS(p))&0x0fff, /* only support 12-Bit sequence space for now */
           bittok2str(ppp_ml_flag_values, "none", *p & 0xc0),
           length));
}

/* CHAP */
static void
handle_chap(netdissect_options *ndo,
            const u_char *p, int length)
{
        u_int code, len;
        int val_size, name_size, msg_size;
        const u_char *p0;
        int i;

        p0 = p;
        if (length < 1) {
                ND_PRINT((ndo, "[|chap]"));
                return;
        } else if (length < 4) {
                ND_TCHECK(*p);
                ND_PRINT((ndo, "[|chap 0x%02x]", *p));
                return;
        }

        ND_TCHECK(*p);
        code = *p;
        ND_PRINT((ndo, "CHAP, %s (0x%02x)",
               tok2str(chapcode_values,"unknown",code),
               code));
        p++;

        ND_TCHECK(*p);
        ND_PRINT((ndo, ", id %u", *p));         /* ID */
        p++;

        ND_TCHECK2(*p, 2);
        len = EXTRACT_16BITS(p);
        p += 2;

        /*
         * Note that this is a generic CHAP decoding routine. Since we
         * don't know which flavor of CHAP (i.e. CHAP-MD5, MS-CHAPv1,
         * MS-CHAPv2) is used at this point, we can't decode packet
         * specifically to each algorithms. Instead, we simply decode
         * the GCD (Gratest Common Denominator) for all algorithms.
         */
        switch (code) {
        case CHAP_CHAL:
        case CHAP_RESP:
                if (length - (p - p0) < 1)
                        return;
                ND_TCHECK(*p);
                val_size = *p;          /* value size */
                p++;
                if (length - (p - p0) < val_size)
                        return;
                ND_PRINT((ndo, ", Value "));
                for (i = 0; i < val_size; i++) {
                        ND_TCHECK(*p);
                        ND_PRINT((ndo, "%02x", *p++));
                }
                name_size = len - (p - p0);
                ND_PRINT((ndo, ", Name "));
                for (i = 0; i < name_size; i++) {
                        ND_TCHECK(*p);
                        safeputchar(ndo, *p++);
                }
                break;
        case CHAP_SUCC:
        case CHAP_FAIL:
                msg_size = len - (p - p0);
                ND_PRINT((ndo, ", Msg "));
                for (i = 0; i< msg_size; i++) {
                        ND_TCHECK(*p);
                        safeputchar(ndo, *p++);
                }
                break;
        }
        return;

trunc:
        ND_PRINT((ndo, "[|chap]"));
}

/* PAP (see RFC 1334) */
static void
handle_pap(netdissect_options *ndo,
           const u_char *p, int length)
{
        u_int code, len;
        int peerid_len, passwd_len, msg_len;
        const u_char *p0;
        int i;

        p0 = p;
        if (length < 1) {
                ND_PRINT((ndo, "[|pap]"));
                return;
        } else if (length < 4) {
                ND_TCHECK(*p);
                ND_PRINT((ndo, "[|pap 0x%02x]", *p));
                return;
        }

        ND_TCHECK(*p);
        code = *p;
        ND_PRINT((ndo, "PAP, %s (0x%02x)",
                  tok2str(papcode_values, "unknown", code),
                  code));
        p++;

        ND_TCHECK(*p);
        ND_PRINT((ndo, ", id %u", *p));         /* ID */
        p++;

        ND_TCHECK2(*p, 2);
        len = EXTRACT_16BITS(p);
        p += 2;

        if ((int)len > length) {
                ND_PRINT((ndo, ", length %u > packet size", len));
                return;
        }
        length = len;
        if (length < (p - p0)) {
                ND_PRINT((ndo, ", length %u < PAP header length", length));
                return;
        }

        switch (code) {
        case PAP_AREQ:
                if (length - (p - p0) < 1)
                        return;
                ND_TCHECK(*p);
                peerid_len = *p;        /* Peer-ID Length */
                p++;
                if (length - (p - p0) < peerid_len)
                        return;
                ND_PRINT((ndo, ", Peer "));
                for (i = 0; i < peerid_len; i++) {
                        ND_TCHECK(*p);
                        safeputchar(ndo, *p++);
                }

                if (length - (p - p0) < 1)
                        return;
                ND_TCHECK(*p);
                passwd_len = *p;        /* Password Length */
                p++;
                if (length - (p - p0) < passwd_len)
                        return;
                ND_PRINT((ndo, ", Name "));
                for (i = 0; i < passwd_len; i++) {
                        ND_TCHECK(*p);
                        safeputchar(ndo, *p++);
                }
                break;
        case PAP_AACK:
        case PAP_ANAK:
                if (length - (p - p0) < 1)
                        return;
                ND_TCHECK(*p);
                msg_len = *p;           /* Msg-Length */
                p++;
                if (length - (p - p0) < msg_len)
                        return;
                ND_PRINT((ndo, ", Msg "));
                for (i = 0; i< msg_len; i++) {
                        ND_TCHECK(*p);
                        safeputchar(ndo, *p++);
                }
                break;
        }
        return;

trunc:
        ND_PRINT((ndo, "[|pap]"));
}

/* BAP */
static void
handle_bap(netdissect_options *ndo _U_,
           const u_char *p _U_, int length _U_)
{
        /* XXX: to be supported!! */
}


/* IPCP config options */
static int
print_ipcp_config_options(netdissect_options *ndo,
                          const u_char *p, int length)
{
        int len, opt;
        u_int compproto, ipcomp_subopttotallen, ipcomp_subopt, ipcomp_suboptlen;

        if (length < 2)
                return 0;
        ND_TCHECK2(*p, 2);
        len = p[1];
        opt = p[0];
        if (length < len)
                return 0;
        if (len < 2) {
                ND_PRINT((ndo, "\n\t  %s Option (0x%02x), length %u (length bogus, should be >= 2)",
                       tok2str(ipcpopt_values,"unknown",opt),
                       opt,
                       len));
                return 0;
        }

        ND_PRINT((ndo, "\n\t  %s Option (0x%02x), length %u",
               tok2str(ipcpopt_values,"unknown",opt),
               opt,
               len));

        switch (opt) {
        case IPCPOPT_2ADDR:             /* deprecated */
                if (len != 10) {
                        ND_PRINT((ndo, " (length bogus, should be = 10)"));
                        return len;
                }
                ND_TCHECK2(*(p + 6), 4);
                ND_PRINT((ndo, ": src %s, dst %s",
                       ipaddr_string(ndo, p + 2),
                       ipaddr_string(ndo, p + 6)));
                break;
        case IPCPOPT_IPCOMP:
                if (len < 4) {
                        ND_PRINT((ndo, " (length bogus, should be >= 4)"));
                        return 0;
                }
                ND_TCHECK2(*(p + 2), 2);
                compproto = EXTRACT_16BITS(p+2);

                ND_PRINT((ndo, ": %s (0x%02x):",
                          tok2str(ipcpopt_compproto_values, "Unknown", compproto),
                          compproto));

                switch (compproto) {
                case PPP_VJC:
                        /* XXX: VJ-Comp parameters should be decoded */
                        break;
                case IPCPOPT_IPCOMP_HDRCOMP:
                        if (len < IPCPOPT_IPCOMP_MINLEN) {
                                ND_PRINT((ndo, " (length bogus, should be >= %u)",
                                        IPCPOPT_IPCOMP_MINLEN));
                                return 0;
                        }

                        ND_TCHECK2(*(p + 2), IPCPOPT_IPCOMP_MINLEN);
                        ND_PRINT((ndo, "\n\t    TCP Space %u, non-TCP Space %u" \
                               ", maxPeriod %u, maxTime %u, maxHdr %u",
                               EXTRACT_16BITS(p+4),
                               EXTRACT_16BITS(p+6),
                               EXTRACT_16BITS(p+8),
                               EXTRACT_16BITS(p+10),
                               EXTRACT_16BITS(p+12)));

                        /* suboptions present ? */
                        if (len > IPCPOPT_IPCOMP_MINLEN) {
                                ipcomp_subopttotallen = len - IPCPOPT_IPCOMP_MINLEN;
                                p += IPCPOPT_IPCOMP_MINLEN;

                                ND_PRINT((ndo, "\n\t      Suboptions, length %u", ipcomp_subopttotallen));

                                while (ipcomp_subopttotallen >= 2) {
                                        ND_TCHECK2(*p, 2);
                                        ipcomp_subopt = *p;
                                        ipcomp_suboptlen = *(p+1);

                                        /* sanity check */
                                        if (ipcomp_subopt == 0 ||
                                            ipcomp_suboptlen == 0 )
                                                break;

                                        /* XXX: just display the suboptions for now */
                                        ND_PRINT((ndo, "\n\t\t%s Suboption #%u, length %u",
                                               tok2str(ipcpopt_compproto_subopt_values,
                                                       "Unknown",
                                                       ipcomp_subopt),
                                               ipcomp_subopt,
                                               ipcomp_suboptlen));

                                        ipcomp_subopttotallen -= ipcomp_suboptlen;
                                        p += ipcomp_suboptlen;
                                }
                        }
                        break;
                default:
                        break;
                }
                break;

        case IPCPOPT_ADDR:     /* those options share the same format - fall through */
        case IPCPOPT_MOBILE4:
        case IPCPOPT_PRIDNS:
        case IPCPOPT_PRINBNS:
        case IPCPOPT_SECDNS:
        case IPCPOPT_SECNBNS:
                if (len != 6) {
                        ND_PRINT((ndo, " (length bogus, should be = 6)"));
                        return 0;
                }
                ND_TCHECK2(*(p + 2), 4);
                ND_PRINT((ndo, ": %s", ipaddr_string(ndo, p + 2)));
                break;
        default:
                /*
                 * Unknown option; dump it as raw bytes now if we're
                 * not going to do so below.
                 */
                if (ndo->ndo_vflag < 2)
                        print_unknown_data(ndo, &p[2], "\n\t    ", len - 2);
                break;
        }
        if (ndo->ndo_vflag > 1)
                print_unknown_data(ndo, &p[2], "\n\t    ", len - 2); /* exclude TLV header */
        return len;

trunc:
        ND_PRINT((ndo, "[|ipcp]"));
        return 0;
}

/* IP6CP config options */
static int
print_ip6cp_config_options(netdissect_options *ndo,
                           const u_char *p, int length)
{
        int len, opt;

        if (length < 2)
                return 0;
        ND_TCHECK2(*p, 2);
        len = p[1];
        opt = p[0];
        if (length < len)
                return 0;
        if (len < 2) {
                ND_PRINT((ndo, "\n\t  %s Option (0x%02x), length %u (length bogus, should be >= 2)",
                       tok2str(ip6cpopt_values,"unknown",opt),
                       opt,
                       len));
                return 0;
        }

        ND_PRINT((ndo, "\n\t  %s Option (0x%02x), length %u",
               tok2str(ip6cpopt_values,"unknown",opt),
               opt,
               len));

        switch (opt) {
        case IP6CP_IFID:
                if (len != 10) {
                        ND_PRINT((ndo, " (length bogus, should be = 10)"));
                        return len;
                }
                ND_TCHECK2(*(p + 2), 8);
                ND_PRINT((ndo, ": %04x:%04x:%04x:%04x",
                       EXTRACT_16BITS(p + 2),
                       EXTRACT_16BITS(p + 4),
                       EXTRACT_16BITS(p + 6),
                       EXTRACT_16BITS(p + 8)));
                break;
        default:
                /*
                 * Unknown option; dump it as raw bytes now if we're
                 * not going to do so below.
                 */
                if (ndo->ndo_vflag < 2)
                        print_unknown_data(ndo, &p[2], "\n\t    ", len - 2);
                break;
        }
        if (ndo->ndo_vflag > 1)
                print_unknown_data(ndo, &p[2], "\n\t    ", len - 2); /* exclude TLV header */

        return len;

trunc:
        ND_PRINT((ndo, "[|ip6cp]"));
        return 0;
}


/* CCP config options */
static int
print_ccp_config_options(netdissect_options *ndo,
                         const u_char *p, int length)
{
        int len, opt;

        if (length < 2)
                return 0;
        ND_TCHECK2(*p, 2);
        len = p[1];
        opt = p[0];
        if (length < len)
                return 0;
        if (len < 2) {
                ND_PRINT((ndo, "\n\t  %s Option (0x%02x), length %u (length bogus, should be >= 2)",
                          tok2str(ccpconfopts_values, "Unknown", opt),
                          opt,
                          len));
                return 0;
        }

        ND_PRINT((ndo, "\n\t  %s Option (0x%02x), length %u",
                  tok2str(ccpconfopts_values, "Unknown", opt),
                  opt,
                  len));

        switch (opt) {
        case CCPOPT_BSDCOMP:
                if (len < 3) {
                        ND_PRINT((ndo, " (length bogus, should be >= 3)"));
                        return len;
                }
                ND_TCHECK2(*(p + 2), 1);
                ND_PRINT((ndo, ": Version: %u, Dictionary Bits: %u",
                        p[2] >> 5, p[2] & 0x1f));
                break;
        case CCPOPT_MVRCA:
                if (len < 4) {
                        ND_PRINT((ndo, " (length bogus, should be >= 4)"));
                        return len;
                }
                ND_TCHECK2(*(p + 2), 1);
                ND_PRINT((ndo, ": Features: %u, PxP: %s, History: %u, #CTX-ID: %u",
                                (p[2] & 0xc0) >> 6,
                                (p[2] & 0x20) ? "Enabled" : "Disabled",
                                p[2] & 0x1f, p[3]));
                break;
        case CCPOPT_DEFLATE:
                if (len < 4) {
                        ND_PRINT((ndo, " (length bogus, should be >= 4)"));
                        return len;
                }
                ND_TCHECK2(*(p + 2), 1);
                ND_PRINT((ndo, ": Window: %uK, Method: %s (0x%x), MBZ: %u, CHK: %u",
                        (p[2] & 0xf0) >> 4,
                        ((p[2] & 0x0f) == 8) ? "zlib" : "unkown",
                        p[2] & 0x0f, (p[3] & 0xfc) >> 2, p[3] & 0x03));
                break;

/* XXX: to be supported */
#if 0
        case CCPOPT_OUI:
        case CCPOPT_PRED1:
        case CCPOPT_PRED2:
        case CCPOPT_PJUMP:
        case CCPOPT_HPPPC:
        case CCPOPT_STACLZS:
        case CCPOPT_MPPC:
        case CCPOPT_GFZA:
        case CCPOPT_V42BIS:
        case CCPOPT_LZSDCP:
        case CCPOPT_DEC:
        case CCPOPT_RESV:
                break;
#endif
        default:
                /*
                 * Unknown option; dump it as raw bytes now if we're
                 * not going to do so below.
                 */
                if (ndo->ndo_vflag < 2)
                        print_unknown_data(ndo, &p[2], "\n\t    ", len - 2);
                break;
        }
        if (ndo->ndo_vflag > 1)
                print_unknown_data(ndo, &p[2], "\n\t    ", len - 2); /* exclude TLV header */

        return len;

trunc:
        ND_PRINT((ndo, "[|ccp]"));
        return 0;
}

/* BACP config options */
static int
print_bacp_config_options(netdissect_options *ndo,
                          const u_char *p, int length)
{
        int len, opt;

        if (length < 2)
                return 0;
        ND_TCHECK2(*p, 2);
        len = p[1];
        opt = p[0];
        if (length < len)
                return 0;
        if (len < 2) {
                ND_PRINT((ndo, "\n\t  %s Option (0x%02x), length %u (length bogus, should be >= 2)",
                          tok2str(bacconfopts_values, "Unknown", opt),
                          opt,
                          len));
                return 0;
        }

        ND_PRINT((ndo, "\n\t  %s Option (0x%02x), length %u",
                  tok2str(bacconfopts_values, "Unknown", opt),
                  opt,
                  len));

        switch (opt) {
        case BACPOPT_FPEER:
                if (len != 6) {
                        ND_PRINT((ndo, " (length bogus, should be = 6)"));
                        return len;
                }
                ND_TCHECK2(*(p + 2), 4);
                ND_PRINT((ndo, ": Magic-Num 0x%08x", EXTRACT_32BITS(p + 2)));
                break;
        default:
                /*
                 * Unknown option; dump it as raw bytes now if we're
                 * not going to do so below.
                 */
                if (ndo->ndo_vflag < 2)
                        print_unknown_data(ndo, &p[2], "\n\t    ", len - 2);
                break;
        }
        if (ndo->ndo_vflag > 1)
                print_unknown_data(ndo, &p[2], "\n\t    ", len - 2); /* exclude TLV header */

        return len;

trunc:
        ND_PRINT((ndo, "[|bacp]"));
        return 0;
}

static void
ppp_hdlc(netdissect_options *ndo,
         const u_char *p, int length)
{
        u_char *b, *t, c;
        const u_char *s;
        int i, proto;
        const void *se;

        if (length <= 0)
                return;

        b = (u_char *)malloc(length);
        if (b == NULL)
                return;

        /*
         * Unescape all the data into a temporary, private, buffer.
         * Do this so that we dont overwrite the original packet
         * contents.
         */
        for (s = p, t = b, i = length; i > 0 && ND_TTEST(*s); i--) {
                c = *s++;
                if (c == 0x7d) {
                        if (i <= 1 || !ND_TTEST(*s))
                                break;
                        i--;
                        c = *s++ ^ 0x20;
                }
                *t++ = c;
        }

        se = ndo->ndo_snapend;
        ndo->ndo_snapend = t;
        length = t - b;

        /* now lets guess about the payload codepoint format */
        if (length < 1)
                goto trunc;
        proto = *b; /* start with a one-octet codepoint guess */

        switch (proto) {
        case PPP_IP:
                ip_print(ndo, b + 1, length - 1);
                goto cleanup;
        case PPP_IPV6:
                ip6_print(ndo, b + 1, length - 1);
                goto cleanup;
        default: /* no luck - try next guess */
                break;
        }

        if (length < 2)
                goto trunc;
        proto = EXTRACT_16BITS(b); /* next guess - load two octets */

        switch (proto) {
        case (PPP_ADDRESS << 8 | PPP_CONTROL): /* looks like a PPP frame */
            if (length < 4)
                goto trunc;
            proto = EXTRACT_16BITS(b+2); /* load the PPP proto-id */
            handle_ppp(ndo, proto, b + 4, length - 4);
            break;
        default: /* last guess - proto must be a PPP proto-id */
            handle_ppp(ndo, proto, b + 2, length - 2);
            break;
        }

cleanup:
        ndo->ndo_snapend = se;
        free(b);
        return;

trunc:
        ndo->ndo_snapend = se;
        free(b);
        ND_PRINT((ndo, "[|ppp]"));
}


/* PPP */
static void
handle_ppp(netdissect_options *ndo,
           u_int proto, const u_char *p, int length)
{
        if ((proto & 0xff00) == 0x7e00) { /* is this an escape code ? */
                ppp_hdlc(ndo, p - 1, length);
                return;
        }

        switch (proto) {
        case PPP_LCP: /* fall through */
        case PPP_IPCP:
        case PPP_OSICP:
        case PPP_MPLSCP:
        case PPP_IPV6CP:
        case PPP_CCP:
        case PPP_BACP:
                handle_ctrl_proto(ndo, proto, p, length);
                break;
        case PPP_ML:
                handle_mlppp(ndo, p, length);
                break;
        case PPP_CHAP:
                handle_chap(ndo, p, length);
                break;
        case PPP_PAP:
                handle_pap(ndo, p, length);
                break;
        case PPP_BAP:           /* XXX: not yet completed */
                handle_bap(ndo, p, length);
                break;
        case ETHERTYPE_IP:      /*XXX*/
        case PPP_VJNC:
        case PPP_IP:
                ip_print(ndo, p, length);
                break;
        case ETHERTYPE_IPV6:    /*XXX*/
        case PPP_IPV6:
                ip6_print(ndo, p, length);
                break;
        case ETHERTYPE_IPX:     /*XXX*/
        case PPP_IPX:
                ipx_print(ndo, p, length);
                break;
        case PPP_OSI:
                isoclns_print(ndo, p, length, length);
                break;
        case PPP_MPLS_UCAST:
        case PPP_MPLS_MCAST:
                mpls_print(ndo, p, length);
                break;
        case PPP_COMP:
                ND_PRINT((ndo, "compressed PPP data"));
                break;
        default:
                ND_PRINT((ndo, "%s ", tok2str(ppptype2str, "unknown PPP protocol (0x%04x)", proto)));
                print_unknown_data(ndo, p, "\n\t", length);
                break;
        }
}

/* Standard PPP printer */
u_int
ppp_print(netdissect_options *ndo,
          register const u_char *p, u_int length)
{
        u_int proto,ppp_header;
        u_int olen = length; /* _o_riginal length */
        u_int hdr_len = 0;

        /*
         * Here, we assume that p points to the Address and Control
         * field (if they present).
         */
        if (length < 2)
                goto trunc;
        ND_TCHECK2(*p, 2);
        ppp_header = EXTRACT_16BITS(p);

        switch(ppp_header) {
        case (PPP_WITHDIRECTION_IN  << 8 | PPP_CONTROL):
            if (ndo->ndo_eflag) ND_PRINT((ndo, "In  "));
            p += 2;
            length -= 2;
            hdr_len += 2;
            break;
        case (PPP_WITHDIRECTION_OUT << 8 | PPP_CONTROL):
            if (ndo->ndo_eflag) ND_PRINT((ndo, "Out "));
            p += 2;
            length -= 2;
            hdr_len += 2;
            break;
        case (PPP_ADDRESS << 8 | PPP_CONTROL):
            p += 2;                     /* ACFC not used */
            length -= 2;
            hdr_len += 2;
            break;

        default:
            break;
        }

        if (length < 2)
                goto trunc;
        ND_TCHECK(*p);
        if (*p % 2) {
                proto = *p;             /* PFC is used */
                p++;
                length--;
                hdr_len++;
        } else {
                ND_TCHECK2(*p, 2);
                proto = EXTRACT_16BITS(p);
                p += 2;
                length -= 2;
                hdr_len += 2;
        }

        if (ndo->ndo_eflag)
                ND_PRINT((ndo, "%s (0x%04x), length %u: ",
                          tok2str(ppptype2str, "unknown", proto),
                          proto,
                          olen));

        handle_ppp(ndo, proto, p, length);
        return (hdr_len);
trunc:
        ND_PRINT((ndo, "[|ppp]"));
        return (0);
}


/* PPP I/F printer */
u_int
ppp_if_print(netdissect_options *ndo,
             const struct pcap_pkthdr *h, register const u_char *p)
{
        register u_int length = h->len;
        register u_int caplen = h->caplen;

        if (caplen < PPP_HDRLEN) {
                ND_PRINT((ndo, "[|ppp]"));
                return (caplen);
        }

#if 0
        /*
         * XXX: seems to assume that there are 2 octets prepended to an
         * actual PPP frame. The 1st octet looks like Input/Output flag
         * while 2nd octet is unknown, at least to me
         * (mshindo@mshindo.net).
         *
         * That was what the original tcpdump code did.
         *
         * FreeBSD's "if_ppp.c" *does* set the first octet to 1 for outbound
         * packets and 0 for inbound packets - but only if the
         * protocol field has the 0x8000 bit set (i.e., it's a network
         * control protocol); it does so before running the packet through
         * "bpf_filter" to see if it should be discarded, and to see
         * if we should update the time we sent the most recent packet...
         *
         * ...but it puts the original address field back after doing
         * so.
         *
         * NetBSD's "if_ppp.c" doesn't set the first octet in that fashion.
         *
         * I don't know if any PPP implementation handed up to a BPF
         * device packets with the first octet being 1 for outbound and
         * 0 for inbound packets, so I (guy@alum.mit.edu) don't know
         * whether that ever needs to be checked or not.
         *
         * Note that NetBSD has a DLT_PPP_SERIAL, which it uses for PPP,
         * and its tcpdump appears to assume that the frame always
         * begins with an address field and a control field, and that
         * the address field might be 0x0f or 0x8f, for Cisco
         * point-to-point with HDLC framing as per section 4.3.1 of RFC
         * 1547, as well as 0xff, for PPP in HDLC-like framing as per
         * RFC 1662.
         *
         * (Is the Cisco framing in question what DLT_C_HDLC, in
         * BSD/OS, is?)
         */
        if (ndo->ndo_eflag)
                ND_PRINT((ndo, "%c %4d %02x ", p[0] ? 'O' : 'I', length, p[1]));
#endif

        ppp_print(ndo, p, length);

        return (0);
}

/*
 * PPP I/F printer to use if we know that RFC 1662-style PPP in HDLC-like
 * framing, or Cisco PPP with HDLC framing as per section 4.3.1 of RFC 1547,
 * is being used (i.e., we don't check for PPP_ADDRESS and PPP_CONTROL,
 * discard them *if* those are the first two octets, and parse the remaining
 * packet as a PPP packet, as "ppp_print()" does).
 *
 * This handles, for example, DLT_PPP_SERIAL in NetBSD.
 */
u_int
ppp_hdlc_if_print(netdissect_options *ndo,
                  const struct pcap_pkthdr *h, register const u_char *p)
{
        register u_int length = h->len;
        register u_int caplen = h->caplen;
        u_int proto;
        u_int hdrlen = 0;

        if (caplen < 2) {
                ND_PRINT((ndo, "[|ppp]"));
                return (caplen);
        }

        switch (p[0]) {

        case PPP_ADDRESS:
                if (caplen < 4) {
                        ND_PRINT((ndo, "[|ppp]"));
                        return (caplen);
                }

                if (ndo->ndo_eflag)
                        ND_PRINT((ndo, "%02x %02x %d ", p[0], p[1], length));
                p += 2;
                length -= 2;
                hdrlen += 2;

                proto = EXTRACT_16BITS(p);
                p += 2;
                length -= 2;
                hdrlen += 2;
                ND_PRINT((ndo, "%s: ", tok2str(ppptype2str, "unknown PPP protocol (0x%04x)", proto)));

                handle_ppp(ndo, proto, p, length);
                break;

        case CHDLC_UNICAST:
        case CHDLC_BCAST:
                return (chdlc_if_print(ndo, h, p));

        default:
                if (ndo->ndo_eflag)
                        ND_PRINT((ndo, "%02x %02x %d ", p[0], p[1], length));
                p += 2;
                hdrlen += 2;

                /*
                 * XXX - NetBSD's "ppp_netbsd_serial_if_print()" treats
                 * the next two octets as an Ethernet type; does that
                 * ever happen?
                 */
                ND_PRINT((ndo, "unknown addr %02x; ctrl %02x", p[0], p[1]));
                break;
        }

        return (hdrlen);
}

#define PPP_BSDI_HDRLEN 24

/* BSD/OS specific PPP printer */
u_int
ppp_bsdos_if_print(netdissect_options *ndo _U_,
                   const struct pcap_pkthdr *h _U_, register const u_char *p _U_)
{
        register int hdrlength;
#ifdef __bsdi__
        register u_int length = h->len;
        register u_int caplen = h->caplen;
        uint16_t ptype;
        const u_char *q;
        int i;

        if (caplen < PPP_BSDI_HDRLEN) {
                ND_PRINT((ndo, "[|ppp]"));
                return (caplen)
        }

        hdrlength = 0;

#if 0
        if (p[0] == PPP_ADDRESS && p[1] == PPP_CONTROL) {
                if (ndo->ndo_eflag)
                        ND_PRINT((ndo, "%02x %02x ", p[0], p[1]));
                p += 2;
                hdrlength = 2;
        }

        if (ndo->ndo_eflag)
                ND_PRINT((ndo, "%d ", length));
        /* Retrieve the protocol type */
        if (*p & 01) {
                /* Compressed protocol field */
                ptype = *p;
                if (ndo->ndo_eflag)
                        ND_PRINT((ndo, "%02x ", ptype));
                p++;
                hdrlength += 1;
        } else {
                /* Un-compressed protocol field */
                ptype = EXTRACT_16BITS(p);
                if (ndo->ndo_eflag)
                        ND_PRINT((ndo, "%04x ", ptype));
                p += 2;
                hdrlength += 2;
        }
#else
        ptype = 0;      /*XXX*/
        if (ndo->ndo_eflag)
                ND_PRINT((ndo, "%c ", p[SLC_DIR] ? 'O' : 'I'));
        if (p[SLC_LLHL]) {
                /* link level header */
                struct ppp_header *ph;

                q = p + SLC_BPFHDRLEN;
                ph = (struct ppp_header *)q;
                if (ph->phdr_addr == PPP_ADDRESS
                 && ph->phdr_ctl == PPP_CONTROL) {
                        if (ndo->ndo_eflag)
                                ND_PRINT((ndo, "%02x %02x ", q[0], q[1]));
                        ptype = EXTRACT_16BITS(&ph->phdr_type);
                        if (ndo->ndo_eflag && (ptype == PPP_VJC || ptype == PPP_VJNC)) {
                                ND_PRINT((ndo, "%s ", tok2str(ppptype2str,
                                                "proto-#%d", ptype)));
                        }
                } else {
                        if (ndo->ndo_eflag) {
                                ND_PRINT((ndo, "LLH=["));
                                for (i = 0; i < p[SLC_LLHL]; i++)
                                        ND_PRINT((ndo, "%02x", q[i]));
                                ND_PRINT((ndo, "] "));
                        }
                }
        }
        if (ndo->ndo_eflag)
                ND_PRINT((ndo, "%d ", length));
        if (p[SLC_CHL]) {
                q = p + SLC_BPFHDRLEN + p[SLC_LLHL];

                switch (ptype) {
                case PPP_VJC:
                        ptype = vjc_print(ndo, q, ptype);
                        hdrlength = PPP_BSDI_HDRLEN;
                        p += hdrlength;
                        switch (ptype) {
                        case PPP_IP:
                                ip_print(ndo, p, length);
                                break;
                        case PPP_IPV6:
                                ip6_print(ndo, p, length);
                                break;
                        case PPP_MPLS_UCAST:
                        case PPP_MPLS_MCAST:
                                mpls_print(ndo, p, length);
                                break;
                        }
                        goto printx;
                case PPP_VJNC:
                        ptype = vjc_print(ndo, q, ptype);
                        hdrlength = PPP_BSDI_HDRLEN;
                        p += hdrlength;
                        switch (ptype) {
                        case PPP_IP:
                                ip_print(ndo, p, length);
                                break;
                        case PPP_IPV6:
                                ip6_print(ndo, p, length);
                                break;
                        case PPP_MPLS_UCAST:
                        case PPP_MPLS_MCAST:
                                mpls_print(ndo, p, length);
                                break;
                        }
                        goto printx;
                default:
                        if (ndo->ndo_eflag) {
                                ND_PRINT((ndo, "CH=["));
                                for (i = 0; i < p[SLC_LLHL]; i++)
                                        ND_PRINT((ndo, "%02x", q[i]));
                                ND_PRINT((ndo, "] "));
                        }
                        break;
                }
        }

        hdrlength = PPP_BSDI_HDRLEN;
#endif

        length -= hdrlength;
        p += hdrlength;

        switch (ptype) {
        case PPP_IP:
                ip_print(p, length);
                break;
        case PPP_IPV6:
                ip6_print(ndo, p, length);
                break;
        case PPP_MPLS_UCAST:
        case PPP_MPLS_MCAST:
                mpls_print(ndo, p, length);
                break;
        default:
                ND_PRINT((ndo, "%s ", tok2str(ppptype2str, "unknown PPP protocol (0x%04x)", ptype)));
        }

printx:
#else /* __bsdi */
        hdrlength = 0;
#endif /* __bsdi__ */
        return (hdrlength);
}


/*
 * Local Variables:
 * c-style: whitesmith
 * c-basic-offset: 8
 * End:
 */