xref: /aosp_15_r20/external/tcpdump/print-fr.c (revision 05b00f6010a2396e3db2409989fc67270046269f)

/*
 * Copyright (c) 1990, 1991, 1993, 1994, 1995, 1996
 *	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.
 */

/* \summary: Frame Relay printer */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include "netdissect-stdinc.h"

#include <stdio.h>
#include <string.h>

#include "netdissect.h"
#include "addrtoname.h"
#include "ethertype.h"
#include "llc.h"
#include "nlpid.h"
#include "extract.h"

static void frf15_print(netdissect_options *ndo, const u_char *, u_int);

/*
 * the frame relay header has a variable length
 *
 * the EA bit determines if there is another byte
 * in the header
 *
 * minimum header length is 2 bytes
 * maximum header length is 4 bytes
 *
 *      7    6    5    4    3    2    1    0
 *    +----+----+----+----+----+----+----+----+
 *    |        DLCI (6 bits)        | CR | EA |
 *    +----+----+----+----+----+----+----+----+
 *    |   DLCI (4 bits)   |FECN|BECN| DE | EA |
 *    +----+----+----+----+----+----+----+----+
 *    |           DLCI (7 bits)          | EA |
 *    +----+----+----+----+----+----+----+----+
 *    |        DLCI (6 bits)        |SDLC| EA |
 *    +----+----+----+----+----+----+----+----+
 */

#define FR_EA_BIT	0x01

#define FR_CR_BIT       0x02000000
#define FR_DE_BIT	0x00020000
#define FR_BECN_BIT	0x00040000
#define FR_FECN_BIT	0x00080000
#define FR_SDLC_BIT	0x00000002


static const struct tok fr_header_flag_values[] = {
    { FR_CR_BIT, "C!" },
    { FR_DE_BIT, "DE" },
    { FR_BECN_BIT, "BECN" },
    { FR_FECN_BIT, "FECN" },
    { FR_SDLC_BIT, "sdlcore" },
    { 0, NULL }
};

/* FRF.15 / FRF.16 */
#define MFR_B_BIT 0x80
#define MFR_E_BIT 0x40
#define MFR_C_BIT 0x20
#define MFR_BEC_MASK    (MFR_B_BIT | MFR_E_BIT | MFR_C_BIT)
#define MFR_CTRL_FRAME  (MFR_B_BIT | MFR_E_BIT | MFR_C_BIT)
#define MFR_FRAG_FRAME  (MFR_B_BIT | MFR_E_BIT )

static const struct tok frf_flag_values[] = {
    { MFR_B_BIT, "Begin" },
    { MFR_E_BIT, "End" },
    { MFR_C_BIT, "Control" },
    { 0, NULL }
};

/* Finds out Q.922 address length, DLCI and flags. Returns 1 on success,
 * 0 on invalid address, -1 on truncated packet
 * save the flags dep. on address length
 */
static int parse_q922_header(netdissect_options *ndo,
                           const u_char *p, u_int *dlci,
                           u_int *addr_len, uint32_t *flags, u_int length)
{
	if (!ND_TTEST_1(p) || length < 1)
		return -1;
	if ((GET_U_1(p) & FR_EA_BIT))
		return 0;

	if (!ND_TTEST_1(p + 1) || length < 2)
		return -1;
	*addr_len = 2;
	*dlci = ((GET_U_1(p) & 0xFC) << 2) | ((GET_U_1(p + 1) & 0xF0) >> 4);

	*flags = ((GET_U_1(p) & 0x02) << 24) |	/* CR flag */
		 ((GET_U_1(p + 1) & 0x0e) << 16);	/* FECN,BECN,DE flags */

	if (GET_U_1(p + 1) & FR_EA_BIT)
		return 1;	/* 2-byte Q.922 address */

	p += 2;
	length -= 2;
	if (!ND_TTEST_1(p) || length < 1)
		return -1;
	(*addr_len)++;		/* 3- or 4-byte Q.922 address */
	if ((GET_U_1(p) & FR_EA_BIT) == 0) {
		*dlci = (*dlci << 7) | (GET_U_1(p) >> 1);
		(*addr_len)++;	/* 4-byte Q.922 address */
		p++;
		length--;
	}

	if (!ND_TTEST_1(p) || length < 1)
		return -1;
	if ((GET_U_1(p) & FR_EA_BIT) == 0)
		return 0; /* more than 4 bytes of Q.922 address? */

	*flags = *flags | (GET_U_1(p) & 0x02);	/* SDLC flag */

        *dlci = (*dlci << 6) | (GET_U_1(p) >> 2);

	return 1;
}

const char *
q922_string(netdissect_options *ndo, const u_char *p, u_int length)
{

    static u_int dlci, addr_len;
    static uint32_t flags;
    static char buffer[sizeof("parse_q922_header() returned XXXXXXXXXXX")];
    int ret;
    memset(buffer, 0, sizeof(buffer));

    ret = parse_q922_header(ndo, p, &dlci, &addr_len, &flags, length);
    if (ret == 1) {
        snprintf(buffer, sizeof(buffer), "DLCI %u", dlci);
        return buffer;
    } else if (ret == 0) {
        return "<Invalid DLCI>";
    } else if (ret == -1) {
        return "<Truncated>";
    } else {
        snprintf(buffer, sizeof(buffer), "parse_q922_header() returned %d", ret);
        return buffer;
    }
}


/* Frame Relay packet structure, with flags and CRC removed

                  +---------------------------+
                  |       Q.922 Address*      |
                  +--                       --+
                  |                           |
                  +---------------------------+
                  | Control (UI = 0x03)       |
                  +---------------------------+
                  | Optional Pad      (0x00)  |
                  +---------------------------+
                  | NLPID                     |
                  +---------------------------+
                  |             .             |
                  |             .             |
                  |             .             |
                  |           Data            |
                  |             .             |
                  |             .             |
                  +---------------------------+

           * Q.922 addresses, as presently defined, are two octets and
             contain a 10-bit DLCI.  In some networks Q.922 addresses
             may optionally be increased to three or four octets.
*/

static void
fr_hdr_print(netdissect_options *ndo, int length, u_int addr_len,
	     u_int dlci, uint32_t flags, uint16_t nlpid)
{
    if (ndo->ndo_qflag) {
        ND_PRINT("Q.922, DLCI %u, length %u: ",
                     dlci,
                     length);
    } else {
        if (nlpid <= 0xff) /* if its smaller than 256 then its a NLPID */
            ND_PRINT("Q.922, hdr-len %u, DLCI %u, Flags [%s], NLPID %s (0x%02x), length %u: ",
                         addr_len,
                         dlci,
                         bittok2str(fr_header_flag_values, "none", flags),
                         tok2str(nlpid_values,"unknown", nlpid),
                         nlpid,
                         length);
        else /* must be an ethertype */
            ND_PRINT("Q.922, hdr-len %u, DLCI %u, Flags [%s], cisco-ethertype %s (0x%04x), length %u: ",
                         addr_len,
                         dlci,
                         bittok2str(fr_header_flag_values, "none", flags),
                         tok2str(ethertype_values, "unknown", nlpid),
                         nlpid,
                         length);
    }
}

/* Frame Relay */
void
fr_if_print(netdissect_options *ndo,
            const struct pcap_pkthdr *h, const u_char *p)
{
	u_int length = h->len;
	u_int caplen = h->caplen;

	ndo->ndo_protocol = "fr";
	if (caplen < 4) {	/* minimum frame header length */
		nd_print_trunc(ndo);
		ndo->ndo_ll_hdr_len += caplen;
		return;
	}

	ndo->ndo_ll_hdr_len += fr_print(ndo, p, length);
}

u_int
fr_print(netdissect_options *ndo,
         const u_char *p, u_int length)
{
	int ret;
	uint16_t extracted_ethertype;
	u_int dlci;
	u_int addr_len;
	uint16_t nlpid;
	u_int hdr_len;
	uint32_t flags;

	ndo->ndo_protocol = "fr";
	ret = parse_q922_header(ndo, p, &dlci, &addr_len, &flags, length);
	if (ret == -1)
		goto trunc;
	if (ret == 0) {
		ND_PRINT("Q.922, invalid address");
		return 0;
	}

	ND_TCHECK_1(p + addr_len);
	if (length < addr_len + 1)
		goto trunc;

	if (GET_U_1(p + addr_len) != LLC_UI && dlci != 0) {
                /*
                 * Let's figure out if we have Cisco-style encapsulation,
                 * with an Ethernet type (Cisco HDLC type?) following the
                 * address.
                 */
		if (!ND_TTEST_2(p + addr_len) || length < addr_len + 2) {
                        /* no Ethertype */
                        ND_PRINT("UI %02x! ", GET_U_1(p + addr_len));
                } else {
                        extracted_ethertype = GET_BE_U_2(p + addr_len);

                        if (ndo->ndo_eflag)
                                fr_hdr_print(ndo, length, addr_len, dlci,
                                    flags, extracted_ethertype);

                        if (ethertype_print(ndo, extracted_ethertype,
                                            p+addr_len+ETHERTYPE_LEN,
                                            length-addr_len-ETHERTYPE_LEN,
                                            ND_BYTES_AVAILABLE_AFTER(p)-addr_len-ETHERTYPE_LEN,
                                            NULL, NULL) == 0)
                                /* ether_type not known, probably it wasn't one */
                                ND_PRINT("UI %02x! ", GET_U_1(p + addr_len));
                        else
                                return addr_len + 2;
                }
        }

	ND_TCHECK_1(p + addr_len + 1);
	if (length < addr_len + 2)
		goto trunc;

	if (GET_U_1(p + addr_len + 1) == 0) {
		/*
		 * Assume a pad byte after the control (UI) byte.
		 * A pad byte should only be used with 3-byte Q.922.
		 */
		if (addr_len != 3)
			ND_PRINT("Pad! ");
		hdr_len = addr_len + 1 /* UI */ + 1 /* pad */ + 1 /* NLPID */;
	} else {
		/*
		 * Not a pad byte.
		 * A pad byte should be used with 3-byte Q.922.
		 */
		if (addr_len == 3)
			ND_PRINT("No pad! ");
		hdr_len = addr_len + 1 /* UI */ + 1 /* NLPID */;
	}

        ND_TCHECK_1(p + hdr_len - 1);
	if (length < hdr_len)
		goto trunc;
	nlpid = GET_U_1(p + hdr_len - 1);

	if (ndo->ndo_eflag)
		fr_hdr_print(ndo, length, addr_len, dlci, flags, nlpid);
	p += hdr_len;
	length -= hdr_len;

	switch (nlpid) {
	case NLPID_IP:
	        ip_print(ndo, p, length);
		break;

	case NLPID_IP6:
		ip6_print(ndo, p, length);
		break;

	case NLPID_CLNP:
	case NLPID_ESIS:
	case NLPID_ISIS:
		isoclns_print(ndo, p - 1, length + 1); /* OSI printers need the NLPID field */
		break;

	case NLPID_SNAP:
		if (snap_print(ndo, p, length, ND_BYTES_AVAILABLE_AFTER(p), NULL, NULL, 0) == 0) {
			/* ether_type not known, print raw packet */
                        if (!ndo->ndo_eflag)
                            fr_hdr_print(ndo, length + hdr_len, hdr_len,
                                         dlci, flags, nlpid);
			if (!ndo->ndo_suppress_default_print)
				ND_DEFAULTPRINT(p - hdr_len, length + hdr_len);
		}
		break;

        case NLPID_Q933:
		q933_print(ndo, p, length);
		break;

        case NLPID_MFR:
                frf15_print(ndo, p, length);
                break;

        case NLPID_PPP:
                ppp_print(ndo, p, length);
                break;

	default:
		if (!ndo->ndo_eflag)
                    fr_hdr_print(ndo, length + hdr_len, addr_len,
				     dlci, flags, nlpid);
		if (!ndo->ndo_xflag)
			ND_DEFAULTPRINT(p, length);
	}

	return hdr_len;

trunc:
        nd_print_trunc(ndo);
        return 0;

}

/* Multi Link Frame Relay (FRF.16) */
void
mfr_if_print(netdissect_options *ndo,
             const struct pcap_pkthdr *h, const u_char *p)
{
	u_int length = h->len;
	u_int caplen = h->caplen;

	ndo->ndo_protocol = "mfr";
	if (caplen < 2) {	/* minimum frame header length */
		nd_print_trunc(ndo);
		ndo->ndo_ll_hdr_len += caplen;
		return;
	}

	ndo->ndo_ll_hdr_len += mfr_print(ndo, p, length);
}


#define MFR_CTRL_MSG_ADD_LINK        1
#define MFR_CTRL_MSG_ADD_LINK_ACK    2
#define MFR_CTRL_MSG_ADD_LINK_REJ    3
#define MFR_CTRL_MSG_HELLO           4
#define MFR_CTRL_MSG_HELLO_ACK       5
#define MFR_CTRL_MSG_REMOVE_LINK     6
#define MFR_CTRL_MSG_REMOVE_LINK_ACK 7

static const struct tok mfr_ctrl_msg_values[] = {
    { MFR_CTRL_MSG_ADD_LINK, "Add Link" },
    { MFR_CTRL_MSG_ADD_LINK_ACK, "Add Link ACK" },
    { MFR_CTRL_MSG_ADD_LINK_REJ, "Add Link Reject" },
    { MFR_CTRL_MSG_HELLO, "Hello" },
    { MFR_CTRL_MSG_HELLO_ACK, "Hello ACK" },
    { MFR_CTRL_MSG_REMOVE_LINK, "Remove Link" },
    { MFR_CTRL_MSG_REMOVE_LINK_ACK, "Remove Link ACK" },
    { 0, NULL }
};

#define MFR_CTRL_IE_BUNDLE_ID  1
#define MFR_CTRL_IE_LINK_ID    2
#define MFR_CTRL_IE_MAGIC_NUM  3
#define MFR_CTRL_IE_TIMESTAMP  5
#define MFR_CTRL_IE_VENDOR_EXT 6
#define MFR_CTRL_IE_CAUSE      7

static const struct tok mfr_ctrl_ie_values[] = {
    { MFR_CTRL_IE_BUNDLE_ID, "Bundle ID"},
    { MFR_CTRL_IE_LINK_ID, "Link ID"},
    { MFR_CTRL_IE_MAGIC_NUM, "Magic Number"},
    { MFR_CTRL_IE_TIMESTAMP, "Timestamp"},
    { MFR_CTRL_IE_VENDOR_EXT, "Vendor Extension"},
    { MFR_CTRL_IE_CAUSE, "Cause"},
    { 0, NULL }
};

#define MFR_ID_STRING_MAXLEN 50

struct ie_tlv_header_t {
    uint8_t ie_type;
    uint8_t ie_len;
};

u_int
mfr_print(netdissect_options *ndo,
          const u_char *p, u_int length)
{
    u_int tlen,idx,hdr_len = 0;
    uint16_t sequence_num;
    uint8_t ie_type,ie_len;
    const uint8_t *tptr;


/*
 * FRF.16 Link Integrity Control Frame
 *
 *      7    6    5    4    3    2    1    0
 *    +----+----+----+----+----+----+----+----+
 *    | B  | E  | C=1| 0    0    0    0  | EA |
 *    +----+----+----+----+----+----+----+----+
 *    | 0    0    0    0    0    0    0    0  |
 *    +----+----+----+----+----+----+----+----+
 *    |              message type             |
 *    +----+----+----+----+----+----+----+----+
 */

    ndo->ndo_protocol = "mfr";

    if (length < 4) {	/* minimum frame header length */
        ND_PRINT("[length %u < 4]", length);
        nd_print_invalid(ndo);
        return length;
    }
    ND_TCHECK_4(p);

    if ((GET_U_1(p) & MFR_BEC_MASK) == MFR_CTRL_FRAME && GET_U_1(p + 1) == 0) {
        ND_PRINT("FRF.16 Control, Flags [%s], %s, length %u",
               bittok2str(frf_flag_values,"none",(GET_U_1(p) & MFR_BEC_MASK)),
               tok2str(mfr_ctrl_msg_values,"Unknown Message (0x%02x)",GET_U_1(p + 2)),
               length);
        tptr = p + 3;
        tlen = length -3;
        hdr_len = 3;

        if (!ndo->ndo_vflag)
            return hdr_len;

        while (tlen>sizeof(struct ie_tlv_header_t)) {
            ND_TCHECK_LEN(tptr, sizeof(struct ie_tlv_header_t));
            ie_type=GET_U_1(tptr);
            ie_len=GET_U_1(tptr + 1);

            ND_PRINT("\n\tIE %s (%u), length %u: ",
                   tok2str(mfr_ctrl_ie_values,"Unknown",ie_type),
                   ie_type,
                   ie_len);

            /* infinite loop check */
            if (ie_type == 0 || ie_len <= sizeof(struct ie_tlv_header_t))
                return hdr_len;

            ND_TCHECK_LEN(tptr, ie_len);
            tptr+=sizeof(struct ie_tlv_header_t);
            /* tlv len includes header */
            ie_len-=sizeof(struct ie_tlv_header_t);
            tlen-=sizeof(struct ie_tlv_header_t);

            switch (ie_type) {

            case MFR_CTRL_IE_MAGIC_NUM:
                /* FRF.16.1 Section 3.4.3 Magic Number Information Element */
                if (ie_len != 4) {
                    ND_PRINT("[IE data length %d != 4]", ie_len);
                    nd_print_invalid(ndo);
                    break;
                }
                ND_PRINT("0x%08x", GET_BE_U_4(tptr));
                break;

            case MFR_CTRL_IE_BUNDLE_ID: /* same message format */
            case MFR_CTRL_IE_LINK_ID:
                for (idx = 0; idx < ie_len && idx < MFR_ID_STRING_MAXLEN; idx++) {
                    if (GET_U_1(tptr + idx) != 0) /* don't print null termination */
                        fn_print_char(ndo, GET_U_1(tptr + idx));
                    else
                        break;
                }
                break;

            case MFR_CTRL_IE_TIMESTAMP:
                if (ie_len == sizeof(struct timeval)) {
                    ts_print(ndo, (const struct timeval *)tptr);
                    break;
                }
                /* fall through and hexdump if no unix timestamp */
                ND_FALL_THROUGH;

                /*
                 * FIXME those are the defined IEs that lack a decoder
                 * you are welcome to contribute code ;-)
                 */

            case MFR_CTRL_IE_VENDOR_EXT:
            case MFR_CTRL_IE_CAUSE:

            default:
                if (ndo->ndo_vflag <= 1)
                    print_unknown_data(ndo, tptr, "\n\t  ", ie_len);
                break;
            }

            /* do we want to see a hexdump of the IE ? */
            if (ndo->ndo_vflag > 1 )
                print_unknown_data(ndo, tptr, "\n\t  ", ie_len);

            tlen-=ie_len;
            tptr+=ie_len;
        }
        return hdr_len;
    }
/*
 * FRF.16 Fragmentation Frame
 *
 *      7    6    5    4    3    2    1    0
 *    +----+----+----+----+----+----+----+----+
 *    | B  | E  | C=0|seq. (high 4 bits) | EA |
 *    +----+----+----+----+----+----+----+----+
 *    |        sequence  (low 8 bits)         |
 *    +----+----+----+----+----+----+----+----+
 *    |        DLCI (6 bits)        | CR | EA |
 *    +----+----+----+----+----+----+----+----+
 *    |   DLCI (4 bits)   |FECN|BECN| DE | EA |
 *    +----+----+----+----+----+----+----+----+
 */

    sequence_num = (GET_U_1(p)&0x1e)<<7 | GET_U_1(p + 1);
    /* whole packet or first fragment ? */
    if ((GET_U_1(p) & MFR_BEC_MASK) == MFR_FRAG_FRAME ||
        (GET_U_1(p) & MFR_BEC_MASK) == MFR_B_BIT) {
        ND_PRINT("FRF.16 Frag, seq %u, Flags [%s], ",
               sequence_num,
               bittok2str(frf_flag_values,"none",(GET_U_1(p) & MFR_BEC_MASK)));
        hdr_len = 2;
        fr_print(ndo, p+hdr_len,length-hdr_len);
        return hdr_len;
    }

    /* must be a middle or the last fragment */
    ND_PRINT("FRF.16 Frag, seq %u, Flags [%s]",
           sequence_num,
           bittok2str(frf_flag_values,"none",(GET_U_1(p) & MFR_BEC_MASK)));
    print_unknown_data(ndo, p, "\n\t", length);

    return hdr_len;

trunc:
    nd_print_trunc(ndo);
    return length;
}

/* an NLPID of 0xb1 indicates a 2-byte
 * FRF.15 header
 *
 *      7    6    5    4    3    2    1    0
 *    +----+----+----+----+----+----+----+----+
 *    ~              Q.922 header             ~
 *    +----+----+----+----+----+----+----+----+
 *    |             NLPID (8 bits)            | NLPID=0xb1
 *    +----+----+----+----+----+----+----+----+
 *    | B  | E  | C  |seq. (high 4 bits) | R  |
 *    +----+----+----+----+----+----+----+----+
 *    |        sequence  (low 8 bits)         |
 *    +----+----+----+----+----+----+----+----+
 */

#define FR_FRF15_FRAGTYPE 0x01

static void
frf15_print(netdissect_options *ndo,
            const u_char *p, u_int length)
{
    uint16_t sequence_num, flags;

    if (length < 2)
        goto trunc;

    flags = GET_U_1(p)&MFR_BEC_MASK;
    sequence_num = (GET_U_1(p)&0x1e)<<7 | GET_U_1(p + 1);

    ND_PRINT("FRF.15, seq 0x%03x, Flags [%s],%s Fragmentation, length %u",
           sequence_num,
           bittok2str(frf_flag_values,"none",flags),
           GET_U_1(p)&FR_FRF15_FRAGTYPE ? "Interface" : "End-to-End",
           length);

/* TODO:
 * depending on all permutations of the B, E and C bit
 * dig as deep as we can - e.g. on the first (B) fragment
 * there is enough payload to print the IP header
 * on non (B) fragments it depends if the fragmentation
 * model is end-to-end or interface based whether we want to print
 * another Q.922 header
 */
    return;

trunc:
    nd_print_trunc(ndo);
}

/*
 * Q.933 decoding portion for framerelay specific.
 */

/* Q.933 packet format
                      Format of Other Protocols
                          using Q.933 NLPID
                  +-------------------------------+
                  |        Q.922 Address          |
                  +---------------+---------------+
                  |Control  0x03  | NLPID   0x08  |
                  +---------------+---------------+
                  |          L2 Protocol ID       |
                  | octet 1       |  octet 2      |
                  +-------------------------------+
                  |          L3 Protocol ID       |
                  | octet 2       |  octet 2      |
                  +-------------------------------+
                  |         Protocol Data         |
                  +-------------------------------+
                  | FCS                           |
                  +-------------------------------+
 */

/* L2 (Octet 1)- Call Reference Usually is 0x0 */

/*
 * L2 (Octet 2)- Message Types definition 1 byte long.
 */
/* Call Establish */
#define MSG_TYPE_ESC_TO_NATIONAL  0x00
#define MSG_TYPE_ALERT            0x01
#define MSG_TYPE_CALL_PROCEEDING  0x02
#define MSG_TYPE_CONNECT          0x07
#define MSG_TYPE_CONNECT_ACK      0x0F
#define MSG_TYPE_PROGRESS         0x03
#define MSG_TYPE_SETUP            0x05
/* Call Clear */
#define MSG_TYPE_DISCONNECT       0x45
#define MSG_TYPE_RELEASE          0x4D
#define MSG_TYPE_RELEASE_COMPLETE 0x5A
#define MSG_TYPE_RESTART          0x46
#define MSG_TYPE_RESTART_ACK      0x4E
/* Status */
#define MSG_TYPE_STATUS           0x7D
#define MSG_TYPE_STATUS_ENQ       0x75

static const struct tok fr_q933_msg_values[] = {
    { MSG_TYPE_ESC_TO_NATIONAL, "ESC to National" },
    { MSG_TYPE_ALERT, "Alert" },
    { MSG_TYPE_CALL_PROCEEDING, "Call proceeding" },
    { MSG_TYPE_CONNECT, "Connect" },
    { MSG_TYPE_CONNECT_ACK, "Connect ACK" },
    { MSG_TYPE_PROGRESS, "Progress" },
    { MSG_TYPE_SETUP, "Setup" },
    { MSG_TYPE_DISCONNECT, "Disconnect" },
    { MSG_TYPE_RELEASE, "Release" },
    { MSG_TYPE_RELEASE_COMPLETE, "Release Complete" },
    { MSG_TYPE_RESTART, "Restart" },
    { MSG_TYPE_RESTART_ACK, "Restart ACK" },
    { MSG_TYPE_STATUS, "Status Reply" },
    { MSG_TYPE_STATUS_ENQ, "Status Enquiry" },
    { 0, NULL }
};

#define IE_IS_SINGLE_OCTET(iecode)	((iecode) & 0x80)
#define IE_IS_SHIFT(iecode)		(((iecode) & 0xF0) == 0x90)
#define IE_SHIFT_IS_NON_LOCKING(iecode)	((iecode) & 0x08)
#define IE_SHIFT_IS_LOCKING(iecode)	(!(IE_SHIFT_IS_NON_LOCKING(iecode)))
#define IE_SHIFT_CODESET(iecode)	((iecode) & 0x07)

#define FR_LMI_ANSI_REPORT_TYPE_IE	0x01
#define FR_LMI_ANSI_LINK_VERIFY_IE_91	0x19 /* details? */
#define FR_LMI_ANSI_LINK_VERIFY_IE	0x03
#define FR_LMI_ANSI_PVC_STATUS_IE	0x07

#define FR_LMI_CCITT_REPORT_TYPE_IE	0x51
#define FR_LMI_CCITT_LINK_VERIFY_IE	0x53
#define FR_LMI_CCITT_PVC_STATUS_IE	0x57

static const struct tok fr_q933_ie_values_codeset_0_5[] = {
    { FR_LMI_ANSI_REPORT_TYPE_IE, "ANSI Report Type" },
    { FR_LMI_ANSI_LINK_VERIFY_IE_91, "ANSI Link Verify" },
    { FR_LMI_ANSI_LINK_VERIFY_IE, "ANSI Link Verify" },
    { FR_LMI_ANSI_PVC_STATUS_IE, "ANSI PVC Status" },
    { FR_LMI_CCITT_REPORT_TYPE_IE, "CCITT Report Type" },
    { FR_LMI_CCITT_LINK_VERIFY_IE, "CCITT Link Verify" },
    { FR_LMI_CCITT_PVC_STATUS_IE, "CCITT PVC Status" },
    { 0, NULL }
};

#define FR_LMI_REPORT_TYPE_IE_FULL_STATUS 0
#define FR_LMI_REPORT_TYPE_IE_LINK_VERIFY 1
#define FR_LMI_REPORT_TYPE_IE_ASYNC_PVC   2

static const struct tok fr_lmi_report_type_ie_values[] = {
    { FR_LMI_REPORT_TYPE_IE_FULL_STATUS, "Full Status" },
    { FR_LMI_REPORT_TYPE_IE_LINK_VERIFY, "Link verify" },
    { FR_LMI_REPORT_TYPE_IE_ASYNC_PVC, "Async PVC Status" },
    { 0, NULL }
};

/* array of 16 codesets - currently we only support codepage 0 and 5 */
static const struct tok *fr_q933_ie_codesets[] = {
    fr_q933_ie_values_codeset_0_5,
    NULL,
    NULL,
    NULL,
    NULL,
    fr_q933_ie_values_codeset_0_5,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL
};

static int fr_q933_print_ie_codeset_0_5(netdissect_options *ndo, u_int iecode,
    u_int ielength, const u_char *p);

typedef int (*codeset_pr_func_t)(netdissect_options *, u_int iecode,
    u_int ielength, const u_char *p);

/* array of 16 codesets - currently we only support codepage 0 and 5 */
static const codeset_pr_func_t fr_q933_print_ie_codeset[] = {
    fr_q933_print_ie_codeset_0_5,
    NULL,
    NULL,
    NULL,
    NULL,
    fr_q933_print_ie_codeset_0_5,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL
};

/*
 * ITU-T Q.933.
 *
 * p points to octet 2, the octet containing the length of the
 * call reference value, so p[n] is octet n+2 ("octet X" is as
 * used in Q.931/Q.933).
 *
 * XXX - actually used both for Q.931 and Q.933.
 */
void
q933_print(netdissect_options *ndo,
           const u_char *p, u_int length)
{
	u_int olen;
	u_int call_ref_length, i;
	uint8_t call_ref[15];	/* maximum length - length field is 4 bits */
	u_int msgtype;
	u_int iecode;
	u_int ielength;
	u_int codeset = 0;
	u_int is_ansi = 0;
	u_int ie_is_known;
	u_int non_locking_shift;
	u_int unshift_codeset;

	ndo->ndo_protocol = "q.933";
	ND_PRINT("%s", ndo->ndo_eflag ? "" : "Q.933");

	if (length == 0 || !ND_TTEST_1(p)) {
		if (!ndo->ndo_eflag)
			ND_PRINT(", ");
		ND_PRINT("length %u", length);
		goto trunc;
	}

	/*
	 * Get the length of the call reference value.
	 */
	olen = length; /* preserve the original length for display */
	call_ref_length = GET_U_1(p) & 0x0f;
	p++;
	length--;

	/*
	 * Get the call reference value.
	 */
	for (i = 0; i < call_ref_length; i++) {
		if (length == 0 || !ND_TTEST_1(p)) {
			if (!ndo->ndo_eflag)
				ND_PRINT(", ");
			ND_PRINT("length %u", olen);
			goto trunc;
		}
		call_ref[i] = GET_U_1(p);
		p++;
		length--;
	}

	/*
	 * Get the message type.
	 */
	if (length == 0 || !ND_TTEST_1(p)) {
		if (!ndo->ndo_eflag)
			ND_PRINT(", ");
		ND_PRINT("length %u", olen);
		goto trunc;
	}
	msgtype = GET_U_1(p);
	p++;
	length--;

	/*
	 * Peek ahead to see if we start with a shift.
	 */
	non_locking_shift = 0;
	unshift_codeset = codeset;
	if (length != 0) {
		if (!ND_TTEST_1(p)) {
			if (!ndo->ndo_eflag)
				ND_PRINT(", ");
			ND_PRINT("length %u", olen);
			goto trunc;
		}
		iecode = GET_U_1(p);
		if (IE_IS_SHIFT(iecode)) {
			/*
			 * It's a shift.  Skip over it.
			 */
			p++;
			length--;

			/*
			 * Get the codeset.
			 */
			codeset = IE_SHIFT_CODESET(iecode);

			/*
			 * If it's a locking shift to codeset 5,
			 * mark this as ANSI.  (XXX - 5 is actually
			 * for national variants in general, not
			 * the US variant in particular, but maybe
			 * this is more American exceptionalism. :-))
			 */
			if (IE_SHIFT_IS_LOCKING(iecode)) {
				/*
				 * It's a locking shift.
				 */
				if (codeset == 5) {
					/*
					 * It's a locking shift to
					 * codeset 5, so this is
					 * T1.617 Annex D.
					 */
					is_ansi = 1;
				}
			} else {
				/*
				 * It's a non-locking shift.
				 * Remember the current codeset, so we
				 * can revert to it after the next IE.
				 */
				non_locking_shift = 1;
				unshift_codeset = 0;
			}
		}
	}

	/* printing out header part */
	if (!ndo->ndo_eflag)
		ND_PRINT(", ");
	ND_PRINT("%s, codeset %u", is_ansi ? "ANSI" : "CCITT", codeset);

	if (call_ref_length != 0) {
		if (call_ref_length > 1 || GET_U_1(p) != 0) {
			/*
			 * Not a dummy call reference.
			 */
			ND_PRINT(", Call Ref: 0x");
			for (i = 0; i < call_ref_length; i++)
				ND_PRINT("%02x", call_ref[i]);
		}
	}
	if (ndo->ndo_vflag) {
		ND_PRINT(", %s (0x%02x), length %u",
		   tok2str(fr_q933_msg_values,
			"unknown message", msgtype),
		   msgtype,
		   olen);
	} else {
		ND_PRINT(", %s",
		       tok2str(fr_q933_msg_values,
			       "unknown message 0x%02x", msgtype));
	}

	/* Loop through the rest of the IEs */
	while (length != 0) {
		/*
		 * What's the state of any non-locking shifts?
		 */
		if (non_locking_shift == 1) {
			/*
			 * There's a non-locking shift in effect for
			 * this IE.  Count it, so we reset the codeset
			 * before the next IE.
			 */
			non_locking_shift = 2;
		} else if (non_locking_shift == 2) {
			/*
			 * Unshift.
			 */
			codeset = unshift_codeset;
			non_locking_shift = 0;
		}

		/*
		 * Get the first octet of the IE.
		 */
		if (!ND_TTEST_1(p)) {
			if (!ndo->ndo_vflag) {
				ND_PRINT(", length %u", olen);
			}
			goto trunc;
		}
		iecode = GET_U_1(p);
		p++;
		length--;

		/* Single-octet IE? */
		if (IE_IS_SINGLE_OCTET(iecode)) {
			/*
			 * Yes.  Is it a shift?
			 */
			if (IE_IS_SHIFT(iecode)) {
				/*
				 * Yes.  Is it locking?
				 */
				if (IE_SHIFT_IS_LOCKING(iecode)) {
					/*
					 * Yes.
					 */
					non_locking_shift = 0;
				} else {
					/*
					 * No.  Remember the current
					 * codeset, so we can revert
					 * to it after the next IE.
					 */
					non_locking_shift = 1;
					unshift_codeset = codeset;
				}

				/*
				 * Get the codeset.
				 */
				codeset = IE_SHIFT_CODESET(iecode);
			}
		} else {
			/*
			 * No.  Get the IE length.
			 */
			if (length == 0 || !ND_TTEST_1(p)) {
				if (!ndo->ndo_vflag) {
					ND_PRINT(", length %u", olen);
				}
				goto trunc;
			}
			ielength = GET_U_1(p);
			p++;
			length--;

			/* lets do the full IE parsing only in verbose mode
			 * however some IEs (DLCI Status, Link Verify)
			 * are also interesting in non-verbose mode */
			if (ndo->ndo_vflag) {
				ND_PRINT("\n\t%s IE (0x%02x), length %u: ",
				    tok2str(fr_q933_ie_codesets[codeset],
					"unknown", iecode),
				    iecode,
				    ielength);
			}

			/* sanity checks */
			if (iecode == 0 || ielength == 0) {
				return;
			}
			if (length < ielength || !ND_TTEST_LEN(p, ielength)) {
				if (!ndo->ndo_vflag) {
					ND_PRINT(", length %u", olen);
				}
				goto trunc;
			}

			ie_is_known = 0;
			if (fr_q933_print_ie_codeset[codeset] != NULL) {
				ie_is_known = fr_q933_print_ie_codeset[codeset](ndo, iecode, ielength, p);
			}

			if (ie_is_known) {
				/*
				 * Known IE; do we want to see a hexdump
				 * of it?
				 */
				if (ndo->ndo_vflag > 1) {
					/* Yes. */
					print_unknown_data(ndo, p, "\n\t  ", ielength);
				}
			} else {
				/*
				 * Unknown IE; if we're printing verbosely,
				 * print its content in hex.
				 */
				if (ndo->ndo_vflag >= 1) {
					print_unknown_data(ndo, p, "\n\t", ielength);
				}
			}

			length -= ielength;
			p += ielength;
		}
	}
	if (!ndo->ndo_vflag) {
	    ND_PRINT(", length %u", olen);
	}
	return;

trunc:
	nd_print_trunc(ndo);
}

static int
fr_q933_print_ie_codeset_0_5(netdissect_options *ndo, u_int iecode,
                          u_int ielength, const u_char *p)
{
        u_int dlci;

        switch (iecode) {

        case FR_LMI_ANSI_REPORT_TYPE_IE: /* fall through */
        case FR_LMI_CCITT_REPORT_TYPE_IE:
            if (ielength < 1) {
                if (!ndo->ndo_vflag) {
                    ND_PRINT(", ");
	        }
                ND_PRINT("Invalid REPORT TYPE IE");
                return 1;
            }
            if (ndo->ndo_vflag) {
                ND_PRINT("%s (%u)",
                       tok2str(fr_lmi_report_type_ie_values,"unknown",GET_U_1(p)),
                       GET_U_1(p));
	    }
            return 1;

        case FR_LMI_ANSI_LINK_VERIFY_IE: /* fall through */
        case FR_LMI_CCITT_LINK_VERIFY_IE:
        case FR_LMI_ANSI_LINK_VERIFY_IE_91:
            if (!ndo->ndo_vflag) {
                ND_PRINT(", ");
	    }
            if (ielength < 2) {
                ND_PRINT("Invalid LINK VERIFY IE");
                return 1;
            }
            ND_PRINT("TX Seq: %3d, RX Seq: %3d", GET_U_1(p), GET_U_1(p + 1));
            return 1;

        case FR_LMI_ANSI_PVC_STATUS_IE: /* fall through */
        case FR_LMI_CCITT_PVC_STATUS_IE:
            if (!ndo->ndo_vflag) {
                ND_PRINT(", ");
	    }
            /* now parse the DLCI information element. */
            if ((ielength < 3) ||
                (GET_U_1(p) & 0x80) ||
                ((ielength == 3) && !(GET_U_1(p + 1) & 0x80)) ||
                ((ielength == 4) &&
                  ((GET_U_1(p + 1) & 0x80) || !(GET_U_1(p + 2) & 0x80))) ||
                ((ielength == 5) &&
                  ((GET_U_1(p + 1) & 0x80) || (GET_U_1(p + 2) & 0x80) ||
                   !(GET_U_1(p + 3) & 0x80))) ||
                (ielength > 5) ||
                !(GET_U_1(p + ielength - 1) & 0x80)) {
                ND_PRINT("Invalid DLCI in PVC STATUS IE");
                return 1;
	    }

            dlci = ((GET_U_1(p) & 0x3F) << 4) | ((GET_U_1(p + 1) & 0x78) >> 3);
            if (ielength == 4) {
                dlci = (dlci << 6) | ((GET_U_1(p + 2) & 0x7E) >> 1);
	    }
            else if (ielength == 5) {
                dlci = (dlci << 13) | (GET_U_1(p + 2) & 0x7F) | ((GET_U_1(p + 3) & 0x7E) >> 1);
	    }

            ND_PRINT("DLCI %u: status %s%s", dlci,
                    GET_U_1(p + ielength - 1) & 0x8 ? "New, " : "",
                    GET_U_1(p + ielength - 1) & 0x2 ? "Active" : "Inactive");
            return 1;
	}

        return 0;
}