* Copyright (c) 1991, 1993, 1994, 1995, 1996, 1997

/*
* Copyright (c) 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.
*
* L2TP support contributed by Motonori Shindo ([email protected])
*/

#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: print-l2tp.c,v 1.11 2024/09/02 16:15:31 christos Exp $");
#endif

/* \summary: Layer Two Tunneling Protocol (L2TP) printer */

/* specification: RFC 2661 */

#include <config.h>

#include "netdissect-stdinc.h"

#include "netdissect.h"
#include "extract.h"

#define L2TP_FLAG_TYPE 0x8000 /* Type (0=Data, 1=Control) */
#define L2TP_FLAG_LENGTH 0x4000 /* Length */
#define L2TP_FLAG_SEQUENCE 0x0800 /* Sequence */
#define L2TP_FLAG_OFFSET 0x0200 /* Offset */
#define L2TP_FLAG_PRIORITY 0x0100 /* Priority */

#define L2TP_VERSION_MASK 0x000f /* Version Mask */
#define L2TP_VERSION_L2F 0x0001 /* L2F */
#define L2TP_VERSION_L2TP 0x0002 /* L2TP */

#define L2TP_AVP_HDR_FLAG_MANDATORY 0x8000 /* Mandatory Flag */
#define L2TP_AVP_HDR_FLAG_HIDDEN 0x4000 /* Hidden Flag */
#define L2TP_AVP_HDR_LEN_MASK 0x03ff /* Length Mask */

#define L2TP_FRAMING_CAP_SYNC_MASK 0x00000001 /* Synchronous */
#define L2TP_FRAMING_CAP_ASYNC_MASK 0x00000002 /* Asynchronous */

#define L2TP_FRAMING_TYPE_SYNC_MASK 0x00000001 /* Synchronous */
#define L2TP_FRAMING_TYPE_ASYNC_MASK 0x00000002 /* Asynchronous */

#define L2TP_BEARER_CAP_DIGITAL_MASK 0x00000001 /* Digital */
#define L2TP_BEARER_CAP_ANALOG_MASK 0x00000002 /* Analog */

#define L2TP_BEARER_TYPE_DIGITAL_MASK 0x00000001 /* Digital */
#define L2TP_BEARER_TYPE_ANALOG_MASK 0x00000002 /* Analog */

/* Authen Type */
#define L2TP_AUTHEN_TYPE_RESERVED 0x0000 /* Reserved */
#define L2TP_AUTHEN_TYPE_TEXTUAL 0x0001 /* Textual username/password exchange */
#define L2TP_AUTHEN_TYPE_CHAP 0x0002 /* PPP CHAP */
#define L2TP_AUTHEN_TYPE_PAP 0x0003 /* PPP PAP */
#define L2TP_AUTHEN_TYPE_NO_AUTH 0x0004 /* No Authentication */
#define L2TP_AUTHEN_TYPE_MSCHAPv1 0x0005 /* MSCHAPv1 */

#define L2TP_PROXY_AUTH_ID_MASK 0x00ff

#define L2TP_MSGTYPE_SCCRQ 1 /* Start-Control-Connection-Request */
#define L2TP_MSGTYPE_SCCRP 2 /* Start-Control-Connection-Reply */
#define L2TP_MSGTYPE_SCCCN 3 /* Start-Control-Connection-Connected */
#define L2TP_MSGTYPE_STOPCCN 4 /* Stop-Control-Connection-Notification */
#define L2TP_MSGTYPE_HELLO 6 /* Hello */
#define L2TP_MSGTYPE_OCRQ 7 /* Outgoing-Call-Request */
#define L2TP_MSGTYPE_OCRP 8 /* Outgoing-Call-Reply */
#define L2TP_MSGTYPE_OCCN 9 /* Outgoing-Call-Connected */
#define L2TP_MSGTYPE_ICRQ 10 /* Incoming-Call-Request */
#define L2TP_MSGTYPE_ICRP 11 /* Incoming-Call-Reply */
#define L2TP_MSGTYPE_ICCN 12 /* Incoming-Call-Connected */
#define L2TP_MSGTYPE_CDN 14 /* Call-Disconnect-Notify */
#define L2TP_MSGTYPE_WEN 15 /* WAN-Error-Notify */
#define L2TP_MSGTYPE_SLI 16 /* Set-Link-Info */

static const struct tok l2tp_msgtype2str[] = {
{ L2TP_MSGTYPE_SCCRQ, "SCCRQ" },
{ L2TP_MSGTYPE_SCCRP, "SCCRP" },
{ L2TP_MSGTYPE_SCCCN, "SCCCN" },
{ L2TP_MSGTYPE_STOPCCN, "StopCCN" },
{ L2TP_MSGTYPE_HELLO, "HELLO" },
{ L2TP_MSGTYPE_OCRQ, "OCRQ" },
{ L2TP_MSGTYPE_OCRP, "OCRP" },
{ L2TP_MSGTYPE_OCCN, "OCCN" },
{ L2TP_MSGTYPE_ICRQ, "ICRQ" },
{ L2TP_MSGTYPE_ICRP, "ICRP" },
{ L2TP_MSGTYPE_ICCN, "ICCN" },
{ L2TP_MSGTYPE_CDN, "CDN" },
{ L2TP_MSGTYPE_WEN, "WEN" },
{ L2TP_MSGTYPE_SLI, "SLI" },
{ 0, NULL }
};

#define L2TP_AVP_MSGTYPE 0 /* Message Type */
#define L2TP_AVP_RESULT_CODE 1 /* Result Code */
#define L2TP_AVP_PROTO_VER 2 /* Protocol Version */
#define L2TP_AVP_FRAMING_CAP 3 /* Framing Capabilities */
#define L2TP_AVP_BEARER_CAP 4 /* Bearer Capabilities */
#define L2TP_AVP_TIE_BREAKER 5 /* Tie Breaker */
#define L2TP_AVP_FIRM_VER 6 /* Firmware Revision */
#define L2TP_AVP_HOST_NAME 7 /* Host Name */
#define L2TP_AVP_VENDOR_NAME 8 /* Vendor Name */
#define L2TP_AVP_ASSND_TUN_ID 9 /* Assigned Tunnel ID */
#define L2TP_AVP_RECV_WIN_SIZE 10 /* Receive Window Size */
#define L2TP_AVP_CHALLENGE 11 /* Challenge */
#define L2TP_AVP_Q931_CC 12 /* Q.931 Cause Code */
#define L2TP_AVP_CHALLENGE_RESP 13 /* Challenge Response */
#define L2TP_AVP_ASSND_SESS_ID 14 /* Assigned Session ID */
#define L2TP_AVP_CALL_SER_NUM 15 /* Call Serial Number */
#define L2TP_AVP_MINIMUM_BPS 16 /* Minimum BPS */
#define L2TP_AVP_MAXIMUM_BPS 17 /* Maximum BPS */
#define L2TP_AVP_BEARER_TYPE 18 /* Bearer Type */
#define L2TP_AVP_FRAMING_TYPE 19 /* Framing Type */
#define L2TP_AVP_PACKET_PROC_DELAY 20 /* Packet Processing Delay (OBSOLETE) */
#define L2TP_AVP_CALLED_NUMBER 21 /* Called Number */
#define L2TP_AVP_CALLING_NUMBER 22 /* Calling Number */
#define L2TP_AVP_SUB_ADDRESS 23 /* Sub-Address */
#define L2TP_AVP_TX_CONN_SPEED 24 /* (Tx) Connect Speed */
#define L2TP_AVP_PHY_CHANNEL_ID 25 /* Physical Channel ID */
#define L2TP_AVP_INI_RECV_LCP 26 /* Initial Received LCP CONFREQ */
#define L2TP_AVP_LAST_SENT_LCP 27 /* Last Sent LCP CONFREQ */
#define L2TP_AVP_LAST_RECV_LCP 28 /* Last Received LCP CONFREQ */
#define L2TP_AVP_PROXY_AUTH_TYPE 29 /* Proxy Authen Type */
#define L2TP_AVP_PROXY_AUTH_NAME 30 /* Proxy Authen Name */
#define L2TP_AVP_PROXY_AUTH_CHAL 31 /* Proxy Authen Challenge */
#define L2TP_AVP_PROXY_AUTH_ID 32 /* Proxy Authen ID */
#define L2TP_AVP_PROXY_AUTH_RESP 33 /* Proxy Authen Response */
#define L2TP_AVP_CALL_ERRORS 34 /* Call Errors */
#define L2TP_AVP_ACCM 35 /* ACCM */
#define L2TP_AVP_RANDOM_VECTOR 36 /* Random Vector */
#define L2TP_AVP_PRIVATE_GRP_ID 37 /* Private Group ID */
#define L2TP_AVP_RX_CONN_SPEED 38 /* (Rx) Connect Speed */
#define L2TP_AVP_SEQ_REQUIRED 39 /* Sequencing Required */
#define L2TP_AVP_PPP_DISCON_CC 46 /* PPP Disconnect Cause Code - RFC 3145 */

static const struct tok l2tp_avp2str[] = {
{ L2TP_AVP_MSGTYPE, "MSGTYPE" },
{ L2TP_AVP_RESULT_CODE, "RESULT_CODE" },
{ L2TP_AVP_PROTO_VER, "PROTO_VER" },
{ L2TP_AVP_FRAMING_CAP, "FRAMING_CAP" },
{ L2TP_AVP_BEARER_CAP, "BEARER_CAP" },
{ L2TP_AVP_TIE_BREAKER, "TIE_BREAKER" },
{ L2TP_AVP_FIRM_VER, "FIRM_VER" },
{ L2TP_AVP_HOST_NAME, "HOST_NAME" },
{ L2TP_AVP_VENDOR_NAME, "VENDOR_NAME" },
{ L2TP_AVP_ASSND_TUN_ID, "ASSND_TUN_ID" },
{ L2TP_AVP_RECV_WIN_SIZE, "RECV_WIN_SIZE" },
{ L2TP_AVP_CHALLENGE, "CHALLENGE" },
{ L2TP_AVP_Q931_CC, "Q931_CC", },
{ L2TP_AVP_CHALLENGE_RESP, "CHALLENGE_RESP" },
{ L2TP_AVP_ASSND_SESS_ID, "ASSND_SESS_ID" },
{ L2TP_AVP_CALL_SER_NUM, "CALL_SER_NUM" },
{ L2TP_AVP_MINIMUM_BPS, "MINIMUM_BPS" },
{ L2TP_AVP_MAXIMUM_BPS, "MAXIMUM_BPS" },
{ L2TP_AVP_BEARER_TYPE, "BEARER_TYPE" },
{ L2TP_AVP_FRAMING_TYPE, "FRAMING_TYPE" },
{ L2TP_AVP_PACKET_PROC_DELAY, "PACKET_PROC_DELAY" },
{ L2TP_AVP_CALLED_NUMBER, "CALLED_NUMBER" },
{ L2TP_AVP_CALLING_NUMBER, "CALLING_NUMBER" },
{ L2TP_AVP_SUB_ADDRESS, "SUB_ADDRESS" },
{ L2TP_AVP_TX_CONN_SPEED, "TX_CONN_SPEED" },
{ L2TP_AVP_PHY_CHANNEL_ID, "PHY_CHANNEL_ID" },
{ L2TP_AVP_INI_RECV_LCP, "INI_RECV_LCP" },
{ L2TP_AVP_LAST_SENT_LCP, "LAST_SENT_LCP" },
{ L2TP_AVP_LAST_RECV_LCP, "LAST_RECV_LCP" },
{ L2TP_AVP_PROXY_AUTH_TYPE, "PROXY_AUTH_TYPE" },
{ L2TP_AVP_PROXY_AUTH_NAME, "PROXY_AUTH_NAME" },
{ L2TP_AVP_PROXY_AUTH_CHAL, "PROXY_AUTH_CHAL" },
{ L2TP_AVP_PROXY_AUTH_ID, "PROXY_AUTH_ID" },
{ L2TP_AVP_PROXY_AUTH_RESP, "PROXY_AUTH_RESP" },
{ L2TP_AVP_CALL_ERRORS, "CALL_ERRORS" },
{ L2TP_AVP_ACCM, "ACCM" },
{ L2TP_AVP_RANDOM_VECTOR, "RANDOM_VECTOR" },
{ L2TP_AVP_PRIVATE_GRP_ID, "PRIVATE_GRP_ID" },
{ L2TP_AVP_RX_CONN_SPEED, "RX_CONN_SPEED" },
{ L2TP_AVP_SEQ_REQUIRED, "SEQ_REQUIRED" },
{ L2TP_AVP_PPP_DISCON_CC, "PPP_DISCON_CC" },
{ 0, NULL }
};

static const struct tok l2tp_authentype2str[] = {
{ L2TP_AUTHEN_TYPE_RESERVED, "Reserved" },
{ L2TP_AUTHEN_TYPE_TEXTUAL, "Textual" },
{ L2TP_AUTHEN_TYPE_CHAP, "CHAP" },
{ L2TP_AUTHEN_TYPE_PAP, "PAP" },
{ L2TP_AUTHEN_TYPE_NO_AUTH, "No Auth" },
{ L2TP_AUTHEN_TYPE_MSCHAPv1, "MS-CHAPv1" },
{ 0, NULL }
};

#define L2TP_PPP_DISCON_CC_DIRECTION_GLOBAL 0
#define L2TP_PPP_DISCON_CC_DIRECTION_AT_PEER 1
#define L2TP_PPP_DISCON_CC_DIRECTION_AT_LOCAL 2

static const struct tok l2tp_cc_direction2str[] = {
{ L2TP_PPP_DISCON_CC_DIRECTION_GLOBAL, "global error" },
{ L2TP_PPP_DISCON_CC_DIRECTION_AT_PEER, "at peer" },
{ L2TP_PPP_DISCON_CC_DIRECTION_AT_LOCAL,"at local" },
{ 0, NULL }
};

#if 0
static char *l2tp_result_code_StopCCN[] = {
"Reserved",
"General request to clear control connection",
"General error--Error Code indicates the problem",
"Control channel already exists",
"Requester is not authorized to establish a control channel",
"The protocol version of the requester is not supported",
"Requester is being shut down",
"Finite State Machine error"
#define L2TP_MAX_RESULT_CODE_STOPCC_INDEX 8
};
#endif

#if 0
static char *l2tp_result_code_CDN[] = {
"Reserved",
"Call disconnected due to loss of carrier",
"Call disconnected for the reason indicated in error code",
"Call disconnected for administrative reasons",
"Call failed due to lack of appropriate facilities being "
"available (temporary condition)",
"Call failed due to lack of appropriate facilities being "
"available (permanent condition)",
"Invalid destination",
"Call failed due to no carrier detected",
"Call failed due to detection of a busy signal",
"Call failed due to lack of a dial tone",
"Call was not established within time allotted by LAC",
"Call was connected but no appropriate framing was detected"
#define L2TP_MAX_RESULT_CODE_CDN_INDEX 12
};
#endif

#if 0
static char *l2tp_error_code_general[] = {
"No general error",
"No control connection exists yet for this LAC-LNS pair",
"Length is wrong",
"One of the field values was out of range or "
"reserved field was non-zero"
"Insufficient resources to handle this operation now",
"The Session ID is invalid in this context",
"A generic vendor-specific error occurred in the LAC",
"Try another"
#define L2TP_MAX_ERROR_CODE_GENERAL_INDEX 8
};
#endif

/******************************/
/* generic print out routines */
/******************************/
static void
print_string(netdissect_options *ndo, const u_char *dat, u_int length)
{
u_int i;
for (i=0; i<length; i++) {
fn_print_char(ndo, GET_U_1(dat));
dat++;
}
}

static void
print_octets(netdissect_options *ndo, const u_char *dat, u_int length)
{
u_int i;
for (i=0; i<length; i++) {
ND_PRINT("%02x", GET_U_1(dat));
dat++;
}
}

static void
print_16bits_val(netdissect_options *ndo, const uint8_t *dat)
{
ND_PRINT("%u", GET_BE_U_2(dat));
}

static void
print_32bits_val(netdissect_options *ndo, const uint8_t *dat)
{
ND_PRINT("%u", GET_BE_U_4(dat));
}

/***********************************/
/* AVP-specific print out routines */
/***********************************/
static void
l2tp_msgtype_print(netdissect_options *ndo, const u_char *dat, u_int length)
{
if (length < 2) {
ND_PRINT("AVP too short");
return;
}
ND_PRINT("%s", tok2str(l2tp_msgtype2str, "MSGTYPE-#%u",
GET_BE_U_2(dat)));
}

static void
l2tp_result_code_print(netdissect_options *ndo, const u_char *dat, u_int length)
{
/* Result Code */
if (length < 2) {
ND_PRINT("AVP too short");
return;
}
ND_PRINT("%u", GET_BE_U_2(dat));
dat += 2;
length -= 2;

/* Error Code (opt) */
if (length == 0)
return;
if (length < 2) {
ND_PRINT(" AVP too short");
return;
}
ND_PRINT("/%u", GET_BE_U_2(dat));
dat += 2;
length -= 2;

/* Error Message (opt) */
if (length == 0)
return;
ND_PRINT(" ");
print_string(ndo, dat, length);
}

static void
l2tp_proto_ver_print(netdissect_options *ndo, const u_char *dat, u_int length)
{
if (length < 2) {
ND_PRINT("AVP too short");
return;
}
ND_PRINT("%u.%u", (GET_BE_U_2(dat) >> 8),
(GET_BE_U_2(dat) & 0xff));
}

static void
l2tp_framing_cap_print(netdissect_options *ndo, const u_char *dat, u_int length)
{
if (length < 4) {
ND_PRINT("AVP too short");
return;
}
if (GET_BE_U_4(dat) & L2TP_FRAMING_CAP_ASYNC_MASK) {
ND_PRINT("A");
}
if (GET_BE_U_4(dat) & L2TP_FRAMING_CAP_SYNC_MASK) {
ND_PRINT("S");
}
}

static void
l2tp_bearer_cap_print(netdissect_options *ndo, const u_char *dat, u_int length)
{
if (length < 4) {
ND_PRINT("AVP too short");
return;
}
if (GET_BE_U_4(dat) & L2TP_BEARER_CAP_ANALOG_MASK) {
ND_PRINT("A");
}
if (GET_BE_U_4(dat) & L2TP_BEARER_CAP_DIGITAL_MASK) {
ND_PRINT("D");
}
}

static void
l2tp_q931_cc_print(netdissect_options *ndo, const u_char *dat, u_int length)
{
if (length < 3) {
ND_PRINT("AVP too short");
return;
}
print_16bits_val(ndo, dat);
ND_PRINT(", %02x", GET_U_1(dat + 2));
dat += 3;
length -= 3;
if (length != 0) {
ND_PRINT(" ");
print_string(ndo, dat, length);
}
}

static void
l2tp_bearer_type_print(netdissect_options *ndo, const u_char *dat, u_int length)
{
if (length < 4) {
ND_PRINT("AVP too short");
return;
}
if (GET_BE_U_4(dat) & L2TP_BEARER_TYPE_ANALOG_MASK) {
ND_PRINT("A");
}
if (GET_BE_U_4(dat) & L2TP_BEARER_TYPE_DIGITAL_MASK) {
ND_PRINT("D");
}
}

static void
l2tp_framing_type_print(netdissect_options *ndo, const u_char *dat, u_int length)
{
if (length < 4) {
ND_PRINT("AVP too short");
return;
}
if (GET_BE_U_4(dat) & L2TP_FRAMING_TYPE_ASYNC_MASK) {
ND_PRINT("A");
}
if (GET_BE_U_4(dat) & L2TP_FRAMING_TYPE_SYNC_MASK) {
ND_PRINT("S");
}
}

static void
l2tp_packet_proc_delay_print(netdissect_options *ndo)
{
ND_PRINT("obsolete");
}

static void
l2tp_proxy_auth_type_print(netdissect_options *ndo, const u_char *dat, u_int length)
{
if (length < 2) {
ND_PRINT("AVP too short");
return;
}
ND_PRINT("%s", tok2str(l2tp_authentype2str,
"AuthType-#%u", GET_BE_U_2(dat)));
}

static void
l2tp_proxy_auth_id_print(netdissect_options *ndo, const u_char *dat, u_int length)
{
if (length < 2) {
ND_PRINT("AVP too short");
return;
}
ND_PRINT("%u", GET_BE_U_2(dat) & L2TP_PROXY_AUTH_ID_MASK);
}

static void
l2tp_call_errors_print(netdissect_options *ndo, const u_char *dat, u_int length)
{
uint32_t val;

if (length < 2) {
ND_PRINT("AVP too short");
return;
}
dat += 2; /* skip "Reserved" */
length -= 2;

if (length < 4) {
ND_PRINT("AVP too short");
return;
}
val = GET_BE_U_4(dat); dat += 4; length -= 4;
ND_PRINT("CRCErr=%u ", val);

if (length < 4) {
ND_PRINT("AVP too short");
return;
}
val = GET_BE_U_4(dat); dat += 4; length -= 4;
ND_PRINT("FrameErr=%u ", val);

if (length < 4) {
ND_PRINT("AVP too short");
return;
}
val = GET_BE_U_4(dat); dat += 4; length -= 4;
ND_PRINT("HardOver=%u ", val);

if (length < 4) {
ND_PRINT("AVP too short");
return;
}
val = GET_BE_U_4(dat); dat += 4; length -= 4;
ND_PRINT("BufOver=%u ", val);

if (length < 4) {
ND_PRINT("AVP too short");
return;
}
val = GET_BE_U_4(dat); dat += 4; length -= 4;
ND_PRINT("Timeout=%u ", val);

if (length < 4) {
ND_PRINT("AVP too short");
return;
}
val = GET_BE_U_4(dat); dat += 4; length -= 4;
ND_PRINT("AlignErr=%u ", val);
}

static void
l2tp_accm_print(netdissect_options *ndo, const u_char *dat, u_int length)
{
uint32_t val;

if (length < 2) {
ND_PRINT("AVP too short");
return;
}
dat += 2; /* skip "Reserved" */
length -= 2;

if (length < 4) {
ND_PRINT("AVP too short");
return;
}
val = GET_BE_U_4(dat); dat += 4; length -= 4;
ND_PRINT("send=%08x ", val);

if (length < 4) {
ND_PRINT("AVP too short");
return;
}
val = GET_BE_U_4(dat); dat += 4; length -= 4;
ND_PRINT("recv=%08x ", val);
}

static void
l2tp_ppp_discon_cc_print(netdissect_options *ndo, const u_char *dat, u_int length)
{
if (length < 5) {
ND_PRINT("AVP too short");
return;
}
/* Disconnect Code */
ND_PRINT("%04x, ", GET_BE_U_2(dat));
dat += 2;
length -= 2;
/* Control Protocol Number */
ND_PRINT("%04x ", GET_BE_U_2(dat));
dat += 2;
length -= 2;
/* Direction */
ND_PRINT("%s", tok2str(l2tp_cc_direction2str,
"Direction-#%u", GET_U_1(dat)));
dat++;
length--;

if (length != 0) {
ND_PRINT(" ");
print_string(ndo, (const u_char *)dat, length);
}
}

static u_int
l2tp_avp_print(netdissect_options *ndo, const u_char *dat, u_int length)
{
u_int len;
uint16_t attr_type;
int hidden = FALSE;

ND_PRINT(" ");
/* Flags & Length */
len = GET_BE_U_2(dat) & L2TP_AVP_HDR_LEN_MASK;

/* If it is not long enough to contain the header, we'll give up. */
if (len < 6)
goto trunc;

/* If it goes past the end of the remaining length of the packet,
we'll give up. */
if (len > (u_int)length)
goto trunc;

/* If it goes past the end of the remaining length of the captured
data, we'll give up. */
ND_TCHECK_LEN(dat, len);

/*
* After this point, we don't need to check whether we go past
* the length of the captured data; however, we *do* need to
* check whether we go past the end of the AVP.
*/

if (GET_BE_U_2(dat) & L2TP_AVP_HDR_FLAG_MANDATORY) {
ND_PRINT("*");
}
if (GET_BE_U_2(dat) & L2TP_AVP_HDR_FLAG_HIDDEN) {
hidden = TRUE;
ND_PRINT("?");
}
dat += 2;

if (GET_BE_U_2(dat)) {
/* Vendor Specific Attribute */
ND_PRINT("VENDOR%04x:", GET_BE_U_2(dat)); dat += 2;
ND_PRINT("ATTR%04x", GET_BE_U_2(dat)); dat += 2;
ND_PRINT("(");
print_octets(ndo, dat, len-6);
ND_PRINT(")");
} else {
/* IETF-defined Attributes */
dat += 2;
attr_type = GET_BE_U_2(dat); dat += 2;
ND_PRINT("%s", tok2str(l2tp_avp2str, "AVP-#%u", attr_type));
ND_PRINT("(");
if (hidden) {
ND_PRINT("???");
} else {
switch (attr_type) {
case L2TP_AVP_MSGTYPE:
l2tp_msgtype_print(ndo, dat, len-6);
break;
case L2TP_AVP_RESULT_CODE:
l2tp_result_code_print(ndo, dat, len-6);
break;
case L2TP_AVP_PROTO_VER:
l2tp_proto_ver_print(ndo, dat, len-6);
break;
case L2TP_AVP_FRAMING_CAP:
l2tp_framing_cap_print(ndo, dat, len-6);
break;
case L2TP_AVP_BEARER_CAP:
l2tp_bearer_cap_print(ndo, dat, len-6);
break;
case L2TP_AVP_TIE_BREAKER:
if (len-6 < 8) {
ND_PRINT("AVP too short");
break;
}
print_octets(ndo, dat, 8);
break;
case L2TP_AVP_FIRM_VER:
case L2TP_AVP_ASSND_TUN_ID:
case L2TP_AVP_RECV_WIN_SIZE:
case L2TP_AVP_ASSND_SESS_ID:
if (len-6 < 2) {
ND_PRINT("AVP too short");
break;
}
print_16bits_val(ndo, dat);
break;
case L2TP_AVP_HOST_NAME:
case L2TP_AVP_VENDOR_NAME:
case L2TP_AVP_CALLING_NUMBER:
case L2TP_AVP_CALLED_NUMBER:
case L2TP_AVP_SUB_ADDRESS:
case L2TP_AVP_PROXY_AUTH_NAME:
case L2TP_AVP_PRIVATE_GRP_ID:
print_string(ndo, dat, len-6);
break;
case L2TP_AVP_CHALLENGE:
case L2TP_AVP_INI_RECV_LCP:
case L2TP_AVP_LAST_SENT_LCP:
case L2TP_AVP_LAST_RECV_LCP:
case L2TP_AVP_PROXY_AUTH_CHAL:
case L2TP_AVP_PROXY_AUTH_RESP:
case L2TP_AVP_RANDOM_VECTOR:
print_octets(ndo, dat, len-6);
break;
case L2TP_AVP_Q931_CC:
l2tp_q931_cc_print(ndo, dat, len-6);
break;
case L2TP_AVP_CHALLENGE_RESP:
if (len-6 < 16) {
ND_PRINT("AVP too short");
break;
}
print_octets(ndo, dat, 16);
break;
case L2TP_AVP_CALL_SER_NUM:
case L2TP_AVP_MINIMUM_BPS:
case L2TP_AVP_MAXIMUM_BPS:
case L2TP_AVP_TX_CONN_SPEED:
case L2TP_AVP_PHY_CHANNEL_ID:
case L2TP_AVP_RX_CONN_SPEED:
if (len-6 < 4) {
ND_PRINT("AVP too short");
break;
}
print_32bits_val(ndo, dat);
break;
case L2TP_AVP_BEARER_TYPE:
l2tp_bearer_type_print(ndo, dat, len-6);
break;
case L2TP_AVP_FRAMING_TYPE:
l2tp_framing_type_print(ndo, dat, len-6);
break;
case L2TP_AVP_PACKET_PROC_DELAY:
l2tp_packet_proc_delay_print(ndo);
break;
case L2TP_AVP_PROXY_AUTH_TYPE:
l2tp_proxy_auth_type_print(ndo, dat, len-6);
break;
case L2TP_AVP_PROXY_AUTH_ID:
l2tp_proxy_auth_id_print(ndo, dat, len-6);
break;
case L2TP_AVP_CALL_ERRORS:
l2tp_call_errors_print(ndo, dat, len-6);
break;
case L2TP_AVP_ACCM:
l2tp_accm_print(ndo, dat, len-6);
break;
case L2TP_AVP_SEQ_REQUIRED:
break; /* No Attribute Value */
case L2TP_AVP_PPP_DISCON_CC:
l2tp_ppp_discon_cc_print(ndo, dat, len-6);
break;
default:
break;
}
}
ND_PRINT(")");
}

return (len);

trunc:
nd_print_trunc(ndo);
return (0);
}

void
l2tp_print(netdissect_options *ndo, const u_char *dat, u_int length)
{
const u_char *ptr = dat;
u_int cnt = 0; /* total octets consumed */
uint16_t pad;
int flag_t, flag_l, flag_s, flag_o;
uint16_t l2tp_len;

ndo->ndo_protocol = "l2tp";
flag_t = flag_l = flag_s = flag_o = FALSE;

if ((GET_BE_U_2(ptr) & L2TP_VERSION_MASK) == L2TP_VERSION_L2TP) {
ND_PRINT(" l2tp:");
} else if ((GET_BE_U_2(ptr) & L2TP_VERSION_MASK) == L2TP_VERSION_L2F) {
ND_PRINT(" l2f:");
return; /* nothing to do */
} else {
ND_PRINT(" Unknown Version, neither L2F(1) nor L2TP(2)");
return; /* nothing we can do */
}

ND_PRINT("[");
if (GET_BE_U_2(ptr) & L2TP_FLAG_TYPE) {
flag_t = TRUE;
ND_PRINT("T");
}
if (GET_BE_U_2(ptr) & L2TP_FLAG_LENGTH) {
flag_l = TRUE;
ND_PRINT("L");
}
if (GET_BE_U_2(ptr) & L2TP_FLAG_SEQUENCE) {
flag_s = TRUE;
ND_PRINT("S");
}
if (GET_BE_U_2(ptr) & L2TP_FLAG_OFFSET) {
flag_o = TRUE;
ND_PRINT("O");
}
if (GET_BE_U_2(ptr) & L2TP_FLAG_PRIORITY)
ND_PRINT("P");
ND_PRINT("]");

ptr += 2;
cnt += 2;

if (flag_l) {
l2tp_len = GET_BE_U_2(ptr);
ptr += 2;
cnt += 2;
} else {
l2tp_len = 0;
}
/* Tunnel ID */
ND_PRINT("(%u/", GET_BE_U_2(ptr));
ptr += 2;
cnt += 2;
/* Session ID */
ND_PRINT("%u)", GET_BE_U_2(ptr));
ptr += 2;
cnt += 2;

if (flag_s) {
ND_PRINT("Ns=%u,", GET_BE_U_2(ptr));
ptr += 2;
cnt += 2;
ND_PRINT("Nr=%u", GET_BE_U_2(ptr));
ptr += 2;
cnt += 2;
}

if (flag_o) { /* Offset Size */
pad = GET_BE_U_2(ptr);
/* Offset padding octets in packet buffer? */
ND_TCHECK_LEN(ptr + 2, pad);
ptr += (2 + pad);
cnt += (2 + pad);
}

if (flag_l) {
if (length < l2tp_len) {
ND_PRINT(" Length %u larger than packet", l2tp_len);
return;
}
length = l2tp_len;
}
if (length < cnt) {
ND_PRINT(" Length %u smaller than header length", length);
return;
}
if (flag_t) {
if (!flag_l) {
ND_PRINT(" No length");
return;
}
if (length - cnt == 0) {
ND_PRINT(" ZLB");
} else {
/*
* Print AVPs.
*/
while (length - cnt != 0) {
u_int avp_length;

avp_length = l2tp_avp_print(ndo, ptr, length - cnt);
if (avp_length == 0) {
/*
* Truncated.
*/
break;
}
cnt += avp_length;
ptr += avp_length;
}
}
} else {
ND_PRINT(" {");
ppp_print(ndo, ptr, length - cnt);
ND_PRINT("}");
}
return;
trunc:
nd_print_trunc(ndo);
}