/*
* Copyright (c) 2001 Protocol Engineering Lab, University of Delaware
*
* Jerry Heinz <[email protected]>
* John Fiore <[email protected]>
* Armando L. Caro Jr. <[email protected]>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
*
* 3. Neither the name of the University nor of the Laboratory may be used
*    to endorse or promote products derived from this software without
*    specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/

#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: print-sctp.c,v 1.11 2024/09/02 16:15:33 christos Exp $");
#endif

/* \summary: Stream Control Transmission Protocol (SCTP) printer */

#include <config.h>

#include "netdissect-stdinc.h"

#include "netdissect.h"
#include "addrtoname.h"
#include "extract.h"
#include "ip.h"
#include "ip6.h"

/* Definitions from:
*
* SCTP reference Implementation Copyright (C) 1999 Cisco And Motorola
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
*
* 3. Neither the name of Cisco nor of Motorola may be used
*    to endorse or promote products derived from this software without
*    specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* This file is part of the SCTP reference Implementation
*
*
* Please send any bug reports or fixes you make to one of the following email
* addresses:
*
* [email protected]
* [email protected]
* [email protected]
*
* Any bugs reported given to us we will try to fix... any fixes shared will
* be incorporated into the next SCTP release.
*/

/* The valid defines for all message
* types know to SCTP. 0 is reserved
*/
#define SCTP_DATA               0x00
#define SCTP_INITIATION         0x01
#define SCTP_INITIATION_ACK     0x02
#define SCTP_SELECTIVE_ACK      0x03
#define SCTP_HEARTBEAT_REQUEST  0x04
#define SCTP_HEARTBEAT_ACK      0x05
#define SCTP_ABORT_ASSOCIATION  0x06
#define SCTP_SHUTDOWN           0x07
#define SCTP_SHUTDOWN_ACK       0x08
#define SCTP_OPERATION_ERR      0x09
#define SCTP_COOKIE_ECHO        0x0a
#define SCTP_COOKIE_ACK         0x0b
#define SCTP_ECN_ECHO           0x0c
#define SCTP_ECN_CWR            0x0d
#define SCTP_SHUTDOWN_COMPLETE  0x0e
#define SCTP_FORWARD_CUM_TSN    0xc0
#define SCTP_RELIABLE_CNTL      0xc1
#define SCTP_RELIABLE_CNTL_ACK  0xc2

static const struct tok sctp_chunkid_str[] = {
       { SCTP_DATA,              "DATA"              },
       { SCTP_INITIATION,        "INIT"              },
       { SCTP_INITIATION_ACK,    "INIT ACK"          },
       { SCTP_SELECTIVE_ACK,     "SACK"              },
       { SCTP_HEARTBEAT_REQUEST, "HB REQ"            },
       { SCTP_HEARTBEAT_ACK,     "HB ACK"            },
       { SCTP_ABORT_ASSOCIATION, "ABORT"             },
       { SCTP_SHUTDOWN,          "SHUTDOWN"          },
       { SCTP_SHUTDOWN_ACK,      "SHUTDOWN ACK"      },
       { SCTP_OPERATION_ERR,     "OP ERR"            },
       { SCTP_COOKIE_ECHO,       "COOKIE ECHO"       },
       { SCTP_COOKIE_ACK,        "COOKIE ACK"        },
       { SCTP_ECN_ECHO,          "ECN ECHO"          },
       { SCTP_ECN_CWR,           "ECN CWR"           },
       { SCTP_SHUTDOWN_COMPLETE, "SHUTDOWN COMPLETE" },
       { SCTP_FORWARD_CUM_TSN,   "FOR CUM TSN"       },
       { SCTP_RELIABLE_CNTL,     "REL CTRL"          },
       { SCTP_RELIABLE_CNTL_ACK, "REL CTRL ACK"      },
       { 0, NULL }
};

/* Data Chuck Specific Flags */
#define SCTP_DATA_FRAG_MASK     0x03
#define SCTP_DATA_MIDDLE_FRAG   0x00
#define SCTP_DATA_LAST_FRAG     0x01
#define SCTP_DATA_FIRST_FRAG    0x02
#define SCTP_DATA_NOT_FRAG      0x03
#define SCTP_DATA_UNORDERED     0x04

#define SCTP_ADDRMAX 60

#define CHAN_HP 6704
#define CHAN_MP 6705
#define CHAN_LP 6706

/* the sctp common header */

struct sctpHeader{
 nd_uint16_t source;
 nd_uint16_t destination;
 nd_uint32_t verificationTag;
 nd_uint32_t adler32;
};

/* various descriptor parsers */

struct sctpChunkDesc{
 nd_uint8_t  chunkID;
 nd_uint8_t  chunkFlg;
 nd_uint16_t chunkLength;
};

struct sctpParamDesc{
 nd_uint16_t paramType;
 nd_uint16_t paramLength;
};


struct sctpRelChunkDesc{
 struct sctpChunkDesc chk;
 nd_uint32_t serialNumber;
};

struct sctpVendorSpecificParam {
 struct sctpParamDesc p;  /* type must be 0xfffe */
 nd_uint32_t vendorId;    /* vendor ID from RFC 1700 */
 nd_uint16_t vendorSpecificType;
 nd_uint16_t vendorSpecificLen;
};


/* Structures for the control parts */



/* Sctp association init request/ack */

/* this is used for init ack, too */
struct sctpInitiation{
 nd_uint32_t initTag;                  /* tag of mine */
 nd_uint32_t rcvWindowCredit;          /* rwnd */
 nd_uint16_t NumPreopenStreams;        /* OS */
 nd_uint16_t MaxInboundStreams;        /* MIS */
 nd_uint32_t initialTSN;
 /* optional param's follow in sctpParamDesc form */
};

struct sctpV4IpAddress{
 struct sctpParamDesc p;       /* type is set to SCTP_IPV4_PARAM_TYPE, len=10 */
 nd_ipv4  ipAddress;
};


struct sctpV6IpAddress{
 struct sctpParamDesc p;       /* type is set to SCTP_IPV6_PARAM_TYPE, len=22 */
 nd_ipv6  ipAddress;
};

struct sctpDNSName{
 struct sctpParamDesc param;
 nd_byte name[1];
};


struct sctpCookiePreserve{
 struct sctpParamDesc p;       /* type is set to SCTP_COOKIE_PRESERVE, len=8 */
 nd_uint32_t extraTime;
};


struct sctpTimeStamp{
 nd_uint32_t ts_sec;
 nd_uint32_t ts_usec;
};


/* this guy is for use when
* I have a initiate message gloming the
* things together.

*/
struct sctpUnifiedInit{
 struct sctpChunkDesc uh;
 struct sctpInitiation initm;
};

struct sctpSendableInit{
 struct sctpHeader mh;
 struct sctpUnifiedInit msg;
};


/* Selective Acknowledgement
* has the following structure with
* a optional amount of trailing int's
* on the last part (based on the numberOfDesc
* field).
*/

struct sctpSelectiveAck{
 nd_uint32_t highestConseqTSN;
 nd_uint32_t updatedRwnd;
 nd_uint16_t numberOfdesc;
 nd_uint16_t numDupTsns;
};

struct sctpSelectiveFrag{
 nd_uint16_t fragmentStart;
 nd_uint16_t fragmentEnd;
};


struct sctpUnifiedSack{
 struct sctpChunkDesc uh;
 struct sctpSelectiveAck sack;
};

/* for the abort and shutdown ACK
* we must carry the init tag in the common header. Just the
* common header is all that is needed with a chunk descriptor.
*/
struct sctpUnifiedAbort{
 struct sctpChunkDesc uh;
};

struct sctpUnifiedAbortLight{
 struct sctpHeader mh;
 struct sctpChunkDesc uh;
};

struct sctpUnifiedAbortHeavy{
 struct sctpHeader mh;
 struct sctpChunkDesc uh;
 nd_uint16_t causeCode;
 nd_uint16_t causeLen;
};

/* For the graceful shutdown we must carry
* the tag (in common header)  and the highest consecutive acking value
*/
struct sctpShutdown {
 nd_uint32_t TSN_Seen;
};

struct sctpUnifiedShutdown{
 struct sctpChunkDesc uh;
 struct sctpShutdown shut;
};

/* in the unified message we add the trailing
* stream id since it is the only message
* that is defined as a operation error.
*/
struct sctpOpErrorCause{
 nd_uint16_t cause;
 nd_uint16_t causeLen;
};

struct sctpUnifiedOpError{
 struct sctpChunkDesc uh;
 struct sctpOpErrorCause c;
};

struct sctpUnifiedStreamError{
 struct sctpHeader mh;
 struct sctpChunkDesc uh;
 struct sctpOpErrorCause c;
 nd_uint16_t strmNum;
 nd_uint16_t reserved;
};

struct staleCookieMsg{
 struct sctpHeader mh;
 struct sctpChunkDesc uh;
 struct sctpOpErrorCause c;
 nd_uint32_t moretime;
};

/* the following is used in all sends
* where nothing is needed except the
* chunk/type i.e. shutdownAck Abort */

struct sctpUnifiedSingleMsg{
 struct sctpHeader mh;
 struct sctpChunkDesc uh;
};

struct sctpDataPart{
 nd_uint32_t TSN;
 nd_uint16_t streamId;
 nd_uint16_t sequence;
 nd_uint32_t payloadtype;
};

struct sctpUnifiedDatagram{
 struct sctpChunkDesc uh;
 struct sctpDataPart dp;
};

struct sctpECN_echo{
 struct sctpChunkDesc uh;
 nd_uint32_t Lowest_TSN;
};


struct sctpCWR{
 struct sctpChunkDesc uh;
 nd_uint32_t TSN_reduced_at;
};

static const struct tok ForCES_channels[] = {
       { CHAN_HP, "ForCES HP" },
       { CHAN_MP, "ForCES MP" },
       { CHAN_LP, "ForCES LP" },
       { 0, NULL }
};

/* data chunk's payload protocol identifiers */

#define SCTP_PPID_IUA 1
#define SCTP_PPID_M2UA 2
#define SCTP_PPID_M3UA 3
#define SCTP_PPID_SUA 4
#define SCTP_PPID_M2PA 5
#define SCTP_PPID_V5UA 6
#define SCTP_PPID_H248 7
#define SCTP_PPID_BICC 8
#define SCTP_PPID_TALI 9
#define SCTP_PPID_DUA 10
#define SCTP_PPID_ASAP 11
#define SCTP_PPID_ENRP 12
#define SCTP_PPID_H323 13
#define SCTP_PPID_QIPC 14
#define SCTP_PPID_SIMCO 15
#define SCTP_PPID_DDPSC 16
#define SCTP_PPID_DDPSSC 17
#define SCTP_PPID_S1AP 18
#define SCTP_PPID_RUA 19
#define SCTP_PPID_HNBAP 20
#define SCTP_PPID_FORCES_HP 21
#define SCTP_PPID_FORCES_MP 22
#define SCTP_PPID_FORCES_LP 23
#define SCTP_PPID_SBC_AP 24
#define SCTP_PPID_NBAP 25
/* 26 */
#define SCTP_PPID_X2AP 27

static const struct tok PayloadProto_idents[] = {
       { SCTP_PPID_IUA,    "ISDN Q.921" },
       { SCTP_PPID_M2UA,   "M2UA"   },
       { SCTP_PPID_M3UA,   "M3UA"   },
       { SCTP_PPID_SUA,    "SUA"    },
       { SCTP_PPID_M2PA,   "M2PA"   },
       { SCTP_PPID_V5UA,   "V5.2"   },
       { SCTP_PPID_H248,   "H.248"  },
       { SCTP_PPID_BICC,   "BICC"   },
       { SCTP_PPID_TALI,   "TALI"   },
       { SCTP_PPID_DUA,    "DUA"    },
       { SCTP_PPID_ASAP,   "ASAP"   },
       { SCTP_PPID_ENRP,   "ENRP"   },
       { SCTP_PPID_H323,   "H.323"  },
       { SCTP_PPID_QIPC,   "Q.IPC"  },
       { SCTP_PPID_SIMCO,  "SIMCO"  },
       { SCTP_PPID_DDPSC,  "DDPSC"  },
       { SCTP_PPID_DDPSSC, "DDPSSC" },
       { SCTP_PPID_S1AP,   "S1AP"   },
       { SCTP_PPID_RUA,    "RUA"    },
       { SCTP_PPID_HNBAP,  "HNBAP"  },
       { SCTP_PPID_FORCES_HP, "ForCES HP" },
       { SCTP_PPID_FORCES_MP, "ForCES MP" },
       { SCTP_PPID_FORCES_LP, "ForCES LP" },
       { SCTP_PPID_SBC_AP, "SBc-AP" },
       { SCTP_PPID_NBAP,   "NBAP"   },
       /* 26 */
       { SCTP_PPID_X2AP,   "X2AP"   },
       { 0, NULL }
};


static int
isForCES_port(u_short Port)
{
       if (Port == CHAN_HP)
               return 1;
       if (Port == CHAN_MP)
               return 1;
       if (Port == CHAN_LP)
               return 1;

       return 0;
}

void
sctp_print(netdissect_options *ndo,
          const u_char *bp,        /* beginning of sctp packet */
          const u_char *bp2,       /* beginning of enclosing */
          u_int sctpPacketLength)  /* ip packet */
{
 u_int sctpPacketLengthRemaining;
 const struct sctpHeader *sctpPktHdr;
 const struct ip *ip;
 const struct ip6_hdr *ip6;
 uint8_t chunkID;
 u_short sourcePort, destPort;
 u_int chunkCount;
 const struct sctpChunkDesc *chunkDescPtr;
 const char *sep;
 int isforces = 0;

 ndo->ndo_protocol = "sctp";
 if (sctpPacketLength < sizeof(struct sctpHeader))
   {
     ND_PRINT("truncated-sctp - %zu bytes missing!",
              sizeof(struct sctpHeader) - sctpPacketLength);
     return;
   }
 sctpPktHdr = (const struct sctpHeader*) bp;
 ND_TCHECK_SIZE(sctpPktHdr);
 sctpPacketLengthRemaining = sctpPacketLength;

 sourcePort = GET_BE_U_2(sctpPktHdr->source);
 destPort = GET_BE_U_2(sctpPktHdr->destination);

 ip = (const struct ip *)bp2;
 if (IP_V(ip) == 6)
   ip6 = (const struct ip6_hdr *)bp2;
 else
   ip6 = NULL;

 if (ip6) {
   ND_PRINT("%s.%u > %s.%u: sctp",
     GET_IP6ADDR_STRING(ip6->ip6_src),
     sourcePort,
     GET_IP6ADDR_STRING(ip6->ip6_dst),
     destPort);
 } else {
   ND_PRINT("%s.%u > %s.%u: sctp",
     GET_IPADDR_STRING(ip->ip_src),
     sourcePort,
     GET_IPADDR_STRING(ip->ip_dst),
     destPort);
 }

 if (isForCES_port(sourcePort)) {
        ND_PRINT("[%s]", tok2str(ForCES_channels, NULL, sourcePort));
        isforces = 1;
 }
 if (isForCES_port(destPort)) {
        ND_PRINT("[%s]", tok2str(ForCES_channels, NULL, destPort));
        isforces = 1;
 }

 bp += sizeof(struct sctpHeader);
 sctpPacketLengthRemaining -= sizeof(struct sctpHeader);

 if (ndo->ndo_vflag >= 2)
   sep = "\n\t";
 else
   sep = " (";
 /* cycle through all chunks, printing information on each one */
 for (chunkCount = 0, chunkDescPtr = (const struct sctpChunkDesc *)bp;
     sctpPacketLengthRemaining != 0;
     chunkCount++)
   {
     uint16_t chunkLength, chunkLengthRemaining;
     uint16_t align;

     chunkDescPtr = (const struct sctpChunkDesc *)bp;
     if (sctpPacketLengthRemaining < sizeof(*chunkDescPtr)) {
       ND_PRINT("%s%u) [chunk descriptor cut off at end of packet]", sep, chunkCount+1);
       break;
     }
     ND_TCHECK_SIZE(chunkDescPtr);
     chunkLength = GET_BE_U_2(chunkDescPtr->chunkLength);
     if (chunkLength < sizeof(*chunkDescPtr)) {
       ND_PRINT("%s%u) [Bad chunk length %u, < size of chunk descriptor]", sep, chunkCount+1, chunkLength);
       break;
     }
     chunkLengthRemaining = chunkLength;

     align = chunkLength % 4;
     if (align != 0)
       align = 4 - align;

     if (sctpPacketLengthRemaining < align) {
       ND_PRINT("%s%u) [Bad chunk length %u, > remaining data in packet]", sep, chunkCount+1, chunkLength);
       break;
     }

     ND_TCHECK_LEN(bp, chunkLength);

     bp += sizeof(*chunkDescPtr);
     sctpPacketLengthRemaining -= sizeof(*chunkDescPtr);
     chunkLengthRemaining -= sizeof(*chunkDescPtr);

     ND_PRINT("%s%u) ", sep, chunkCount+1);
     chunkID = GET_U_1(chunkDescPtr->chunkID);
     ND_PRINT("[%s] ", tok2str(sctp_chunkid_str, "Unknown chunk type: 0x%x",
              chunkID));
     switch (chunkID) {
       case SCTP_DATA :
         {
           const struct sctpDataPart *dataHdrPtr;
           uint8_t chunkFlg;
           uint32_t ppid;
           uint16_t payload_size;

           chunkFlg = GET_U_1(chunkDescPtr->chunkFlg);
           if ((chunkFlg & SCTP_DATA_UNORDERED) == SCTP_DATA_UNORDERED)
             ND_PRINT("(U)");

           if ((chunkFlg & SCTP_DATA_FIRST_FRAG) == SCTP_DATA_FIRST_FRAG)
             ND_PRINT("(B)");

           if ((chunkFlg & SCTP_DATA_LAST_FRAG) == SCTP_DATA_LAST_FRAG)
             ND_PRINT("(E)");

           if( ((chunkFlg & SCTP_DATA_UNORDERED) == SCTP_DATA_UNORDERED) ||
               ((chunkFlg & SCTP_DATA_FIRST_FRAG) == SCTP_DATA_FIRST_FRAG) ||
               ((chunkFlg & SCTP_DATA_LAST_FRAG) == SCTP_DATA_LAST_FRAG) )
             ND_PRINT(" ");

           if (chunkLengthRemaining < sizeof(*dataHdrPtr)) {
               ND_PRINT("bogus chunk length %u]", chunkLength);
               return;
           }
           dataHdrPtr=(const struct sctpDataPart*)bp;

           ppid = GET_BE_U_4(dataHdrPtr->payloadtype);
           ND_PRINT("[TSN: %u] ", GET_BE_U_4(dataHdrPtr->TSN));
           ND_PRINT("[SID: %u] ", GET_BE_U_2(dataHdrPtr->streamId));
           ND_PRINT("[SSEQ %u] ", GET_BE_U_2(dataHdrPtr->sequence));
           ND_PRINT("[PPID %s] ",
                   tok2str(PayloadProto_idents, "0x%x", ppid));

           if (!isforces) {
               isforces = (ppid == SCTP_PPID_FORCES_HP) ||
                   (ppid == SCTP_PPID_FORCES_MP) ||
                   (ppid == SCTP_PPID_FORCES_LP);
           }

           bp += sizeof(*dataHdrPtr);
           sctpPacketLengthRemaining -= sizeof(*dataHdrPtr);
           chunkLengthRemaining -= sizeof(*dataHdrPtr);
           payload_size = chunkLengthRemaining;
           if (payload_size == 0) {
               ND_PRINT("bogus chunk length %u]", chunkLength);
               return;
           }

           if (isforces) {
               forces_print(ndo, bp, payload_size);
               /* ndo_protocol reassignment after forces_print() call */
               ndo->ndo_protocol = "sctp";
           } else if (ndo->ndo_vflag >= 2) {   /* if verbose output is specified */
                                       /* at the command line */
               switch (ppid) {
               case SCTP_PPID_M3UA :
                       m3ua_print(ndo, bp, payload_size);
                       /* ndo_protocol reassignment after m3ua_print() call */
                       ndo->ndo_protocol = "sctp";
                       break;
               default:
                       ND_PRINT("[Payload");
                       if (!ndo->ndo_suppress_default_print) {
                               ND_PRINT(":");
                               ND_DEFAULTPRINT(bp, payload_size);
                       }
                       ND_PRINT("]");
                       break;
               }
           }
           bp += payload_size;
           sctpPacketLengthRemaining -= payload_size;
           chunkLengthRemaining -= payload_size;
           break;
         }
       case SCTP_INITIATION :
         {
           const struct sctpInitiation *init;

           if (chunkLengthRemaining < sizeof(*init)) {
               ND_PRINT("bogus chunk length %u]", chunkLength);
               return;
           }
           init=(const struct sctpInitiation*)bp;
           ND_PRINT("[init tag: %u] ", GET_BE_U_4(init->initTag));
           ND_PRINT("[rwnd: %u] ", GET_BE_U_4(init->rcvWindowCredit));
           ND_PRINT("[OS: %u] ", GET_BE_U_2(init->NumPreopenStreams));
           ND_PRINT("[MIS: %u] ", GET_BE_U_2(init->MaxInboundStreams));
           ND_PRINT("[init TSN: %u] ", GET_BE_U_4(init->initialTSN));
           bp += sizeof(*init);
           sctpPacketLengthRemaining -= sizeof(*init);
           chunkLengthRemaining -= sizeof(*init);

#if 0 /* ALC you can add code for optional params here */
           if( chunkLengthRemaining != 0 )
             ND_PRINT(" @@@@@ UNFINISHED @@@@@@%s\n",
                    "Optional params present, but not printed.");
#endif
           bp += chunkLengthRemaining;
           sctpPacketLengthRemaining -= chunkLengthRemaining;
           chunkLengthRemaining = 0;
           break;
         }
       case SCTP_INITIATION_ACK :
         {
           const struct sctpInitiation *init;

           if (chunkLengthRemaining < sizeof(*init)) {
               ND_PRINT("bogus chunk length %u]", chunkLength);
               return;
           }
           init=(const struct sctpInitiation*)bp;
           ND_PRINT("[init tag: %u] ", GET_BE_U_4(init->initTag));
           ND_PRINT("[rwnd: %u] ", GET_BE_U_4(init->rcvWindowCredit));
           ND_PRINT("[OS: %u] ", GET_BE_U_2(init->NumPreopenStreams));
           ND_PRINT("[MIS: %u] ", GET_BE_U_2(init->MaxInboundStreams));
           ND_PRINT("[init TSN: %u] ", GET_BE_U_4(init->initialTSN));
           bp += sizeof(*init);
           sctpPacketLengthRemaining -= sizeof(*init);
           chunkLengthRemaining -= sizeof(*init);

#if 0 /* ALC you can add code for optional params here */
           if( chunkLengthRemaining != 0 )
             ND_PRINT(" @@@@@ UNFINISHED @@@@@@%s\n",
                    "Optional params present, but not printed.");
#endif
           bp += chunkLengthRemaining;
           sctpPacketLengthRemaining -= chunkLengthRemaining;
           chunkLengthRemaining = 0;
           break;
         }
       case SCTP_SELECTIVE_ACK:
         {
           const struct sctpSelectiveAck *sack;
           const struct sctpSelectiveFrag *frag;
           u_int fragNo, tsnNo;
           const u_char *dupTSN;

           if (chunkLengthRemaining < sizeof(*sack)) {
             ND_PRINT("bogus chunk length %u]", chunkLength);
             return;
           }
           sack=(const struct sctpSelectiveAck*)bp;
           ND_PRINT("[cum ack %u] ", GET_BE_U_4(sack->highestConseqTSN));
           ND_PRINT("[a_rwnd %u] ", GET_BE_U_4(sack->updatedRwnd));
           ND_PRINT("[#gap acks %u] ", GET_BE_U_2(sack->numberOfdesc));
           ND_PRINT("[#dup tsns %u] ", GET_BE_U_2(sack->numDupTsns));
           bp += sizeof(*sack);
           sctpPacketLengthRemaining -= sizeof(*sack);
           chunkLengthRemaining -= sizeof(*sack);


           /* print gaps */
           for (fragNo=0;
                chunkLengthRemaining != 0 && fragNo < GET_BE_U_2(sack->numberOfdesc);
                bp += sizeof(*frag), sctpPacketLengthRemaining -= sizeof(*frag), chunkLengthRemaining -= sizeof(*frag), fragNo++) {
             if (chunkLengthRemaining < sizeof(*frag)) {
               ND_PRINT("bogus chunk length %u]", chunkLength);
               return;
             }
             frag = (const struct sctpSelectiveFrag *)bp;
             ND_PRINT("\n\t\t[gap ack block #%u: start = %u, end = %u] ",
                    fragNo+1,
                    GET_BE_U_4(sack->highestConseqTSN) + GET_BE_U_2(frag->fragmentStart),
                    GET_BE_U_4(sack->highestConseqTSN) + GET_BE_U_2(frag->fragmentEnd));
           }

           /* print duplicate TSNs */
           for (tsnNo=0;
                chunkLengthRemaining != 0 && tsnNo<GET_BE_U_2(sack->numDupTsns);
                bp += 4, sctpPacketLengthRemaining -= 4, chunkLengthRemaining -= 4, tsnNo++) {
             if (chunkLengthRemaining < 4) {
               ND_PRINT("bogus chunk length %u]", chunkLength);
               return;
             }
             dupTSN = (const u_char *)bp;
             ND_PRINT("\n\t\t[dup TSN #%u: %u] ", tsnNo+1,
                      GET_BE_U_4(dupTSN));
           }
           break;
         }
       default :
         {
           bp += chunkLengthRemaining;
           sctpPacketLengthRemaining -= chunkLengthRemaining;
           chunkLengthRemaining = 0;
           break;
         }
       }

     /*
      * Any extra stuff at the end of the chunk?
      * XXX - report this?
      */
     bp += chunkLengthRemaining;
     sctpPacketLengthRemaining -= chunkLengthRemaining;

     if (ndo->ndo_vflag < 2)
       sep = ", (";

     if (align != 0) {
       /*
        * Fail if the alignment padding isn't in the captured data.
        * Otherwise, skip it.
        */
       ND_TCHECK_LEN(bp, align);
       bp += align;
       sctpPacketLengthRemaining -= align;
     }
   }
   return;

trunc:
   nd_print_trunc(ndo);
}