xref: /netbsd-src/external/bsd/tcpdump/dist/print-sctp.c (revision 6cfa3b0f83a4f3a0b46d134791324141951f2bc4)
1 /*
2  * Copyright (c) 2001 Protocol Engineering Lab, University of Delaware
3  *
4  * Jerry Heinz <gheinz@astro.temple.edu>
5  * John Fiore <jfiore@joda.cis.temple.edu>
6  * Armando L. Caro Jr. <acaro@cis.udel.edu>
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  *
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  *
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  *
19  * 3. Neither the name of the University nor of the Laboratory may be used
20  *    to endorse or promote products derived from this software without
21  *    specific prior written permission.
22  *
23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33  * SUCH DAMAGE.
34  */
35 
36 #include <sys/cdefs.h>
37 #ifndef lint
38 __RCSID("$NetBSD: print-sctp.c,v 1.10 2023/08/17 20:19:40 christos Exp $");
39 #endif
40 
41 /* \summary: Stream Control Transmission Protocol (SCTP) printer */
42 
43 #ifdef HAVE_CONFIG_H
44 #include <config.h>
45 #endif
46 
47 #include "netdissect-stdinc.h"
48 
49 #include "netdissect.h"
50 #include "addrtoname.h"
51 #include "extract.h"
52 #include "ip.h"
53 #include "ip6.h"
54 
55 /* Definitions from:
56  *
57  * SCTP reference Implementation Copyright (C) 1999 Cisco And Motorola
58  *
59  * Redistribution and use in source and binary forms, with or without
60  * modification, are permitted provided that the following conditions
61  * are met:
62  *
63  * 1. Redistributions of source code must retain the above copyright
64  *    notice, this list of conditions and the following disclaimer.
65  *
66  * 2. Redistributions in binary form must reproduce the above copyright
67  *    notice, this list of conditions and the following disclaimer in the
68  *    documentation and/or other materials provided with the distribution.
69  *
70  * 3. Neither the name of Cisco nor of Motorola may be used
71  *    to endorse or promote products derived from this software without
72  *    specific prior written permission.
73  *
74  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
75  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
76  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
77  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
78  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
79  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
80  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
81  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
82  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
83  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
84  * SUCH DAMAGE.
85  *
86  * This file is part of the SCTP reference Implementation
87  *
88  *
89  * Please send any bug reports or fixes you make to one of the following email
90  * addresses:
91  *
92  * rstewar1@email.mot.com
93  * kmorneau@cisco.com
94  * qxie1@email.mot.com
95  *
96  * Any bugs reported given to us we will try to fix... any fixes shared will
97  * be incorporated into the next SCTP release.
98  */
99 
100 /* The valid defines for all message
101  * types know to SCTP. 0 is reserved
102  */
103 #define SCTP_DATA		0x00
104 #define SCTP_INITIATION		0x01
105 #define SCTP_INITIATION_ACK	0x02
106 #define SCTP_SELECTIVE_ACK	0x03
107 #define SCTP_HEARTBEAT_REQUEST	0x04
108 #define SCTP_HEARTBEAT_ACK	0x05
109 #define SCTP_ABORT_ASSOCIATION	0x06
110 #define SCTP_SHUTDOWN		0x07
111 #define SCTP_SHUTDOWN_ACK	0x08
112 #define SCTP_OPERATION_ERR	0x09
113 #define SCTP_COOKIE_ECHO	0x0a
114 #define SCTP_COOKIE_ACK         0x0b
115 #define SCTP_ECN_ECHO		0x0c
116 #define SCTP_ECN_CWR		0x0d
117 #define SCTP_SHUTDOWN_COMPLETE	0x0e
118 #define SCTP_FORWARD_CUM_TSN    0xc0
119 #define SCTP_RELIABLE_CNTL      0xc1
120 #define SCTP_RELIABLE_CNTL_ACK  0xc2
121 
122 static const struct tok sctp_chunkid_str[] = {
123 	{ SCTP_DATA,              "DATA"              },
124 	{ SCTP_INITIATION,        "INIT"              },
125 	{ SCTP_INITIATION_ACK,    "INIT ACK"          },
126 	{ SCTP_SELECTIVE_ACK,     "SACK"              },
127 	{ SCTP_HEARTBEAT_REQUEST, "HB REQ"            },
128 	{ SCTP_HEARTBEAT_ACK,     "HB ACK"            },
129 	{ SCTP_ABORT_ASSOCIATION, "ABORT"             },
130 	{ SCTP_SHUTDOWN,          "SHUTDOWN"          },
131 	{ SCTP_SHUTDOWN_ACK,      "SHUTDOWN ACK"      },
132 	{ SCTP_OPERATION_ERR,     "OP ERR"            },
133 	{ SCTP_COOKIE_ECHO,       "COOKIE ECHO"       },
134 	{ SCTP_COOKIE_ACK,        "COOKIE ACK"        },
135 	{ SCTP_ECN_ECHO,          "ECN ECHO"          },
136 	{ SCTP_ECN_CWR,           "ECN CWR"           },
137 	{ SCTP_SHUTDOWN_COMPLETE, "SHUTDOWN COMPLETE" },
138 	{ SCTP_FORWARD_CUM_TSN,   "FOR CUM TSN"       },
139 	{ SCTP_RELIABLE_CNTL,     "REL CTRL"          },
140 	{ SCTP_RELIABLE_CNTL_ACK, "REL CTRL ACK"      },
141 	{ 0, NULL }
142 };
143 
144 /* Data Chuck Specific Flags */
145 #define SCTP_DATA_FRAG_MASK	0x03
146 #define SCTP_DATA_MIDDLE_FRAG	0x00
147 #define SCTP_DATA_LAST_FRAG	0x01
148 #define SCTP_DATA_FIRST_FRAG	0x02
149 #define SCTP_DATA_NOT_FRAG	0x03
150 #define SCTP_DATA_UNORDERED	0x04
151 
152 #define SCTP_ADDRMAX 60
153 
154 #define CHAN_HP 6704
155 #define CHAN_MP 6705
156 #define CHAN_LP 6706
157 
158 /* the sctp common header */
159 
160 struct sctpHeader{
161   nd_uint16_t source;
162   nd_uint16_t destination;
163   nd_uint32_t verificationTag;
164   nd_uint32_t adler32;
165 };
166 
167 /* various descriptor parsers */
168 
169 struct sctpChunkDesc{
170   nd_uint8_t  chunkID;
171   nd_uint8_t  chunkFlg;
172   nd_uint16_t chunkLength;
173 };
174 
175 struct sctpParamDesc{
176   nd_uint16_t paramType;
177   nd_uint16_t paramLength;
178 };
179 
180 
181 struct sctpRelChunkDesc{
182   struct sctpChunkDesc chk;
183   nd_uint32_t serialNumber;
184 };
185 
186 struct sctpVendorSpecificParam {
187   struct sctpParamDesc p;  /* type must be 0xfffe */
188   nd_uint32_t vendorId;	   /* vendor ID from RFC 1700 */
189   nd_uint16_t vendorSpecificType;
190   nd_uint16_t vendorSpecificLen;
191 };
192 
193 
194 /* Structures for the control parts */
195 
196 
197 
198 /* Sctp association init request/ack */
199 
200 /* this is used for init ack, too */
201 struct sctpInitiation{
202   nd_uint32_t initTag;			/* tag of mine */
203   nd_uint32_t rcvWindowCredit;		/* rwnd */
204   nd_uint16_t NumPreopenStreams;	/* OS */
205   nd_uint16_t MaxInboundStreams;	/* MIS */
206   nd_uint32_t initialTSN;
207   /* optional param's follow in sctpParamDesc form */
208 };
209 
210 struct sctpV4IpAddress{
211   struct sctpParamDesc p;	/* type is set to SCTP_IPV4_PARAM_TYPE, len=10 */
212   nd_ipv4  ipAddress;
213 };
214 
215 
216 struct sctpV6IpAddress{
217   struct sctpParamDesc p;	/* type is set to SCTP_IPV6_PARAM_TYPE, len=22 */
218   nd_ipv6  ipAddress;
219 };
220 
221 struct sctpDNSName{
222   struct sctpParamDesc param;
223   nd_byte name[1];
224 };
225 
226 
227 struct sctpCookiePreserve{
228   struct sctpParamDesc p;	/* type is set to SCTP_COOKIE_PRESERVE, len=8 */
229   nd_uint32_t extraTime;
230 };
231 
232 
233 struct sctpTimeStamp{
234   nd_uint32_t ts_sec;
235   nd_uint32_t ts_usec;
236 };
237 
238 
239 /* this guy is for use when
240  * I have a initiate message gloming the
241  * things together.
242 
243  */
244 struct sctpUnifiedInit{
245   struct sctpChunkDesc uh;
246   struct sctpInitiation initm;
247 };
248 
249 struct sctpSendableInit{
250   struct sctpHeader mh;
251   struct sctpUnifiedInit msg;
252 };
253 
254 
255 /* Selective Acknowledgement
256  * has the following structure with
257  * a optional amount of trailing int's
258  * on the last part (based on the numberOfDesc
259  * field).
260  */
261 
262 struct sctpSelectiveAck{
263   nd_uint32_t highestConseqTSN;
264   nd_uint32_t updatedRwnd;
265   nd_uint16_t numberOfdesc;
266   nd_uint16_t numDupTsns;
267 };
268 
269 struct sctpSelectiveFrag{
270   nd_uint16_t fragmentStart;
271   nd_uint16_t fragmentEnd;
272 };
273 
274 
275 struct sctpUnifiedSack{
276   struct sctpChunkDesc uh;
277   struct sctpSelectiveAck sack;
278 };
279 
280 /* for the abort and shutdown ACK
281  * we must carry the init tag in the common header. Just the
282  * common header is all that is needed with a chunk descriptor.
283  */
284 struct sctpUnifiedAbort{
285   struct sctpChunkDesc uh;
286 };
287 
288 struct sctpUnifiedAbortLight{
289   struct sctpHeader mh;
290   struct sctpChunkDesc uh;
291 };
292 
293 struct sctpUnifiedAbortHeavy{
294   struct sctpHeader mh;
295   struct sctpChunkDesc uh;
296   nd_uint16_t causeCode;
297   nd_uint16_t causeLen;
298 };
299 
300 /* For the graceful shutdown we must carry
301  * the tag (in common header)  and the highest consequitive acking value
302  */
303 struct sctpShutdown {
304   nd_uint32_t TSN_Seen;
305 };
306 
307 struct sctpUnifiedShutdown{
308   struct sctpChunkDesc uh;
309   struct sctpShutdown shut;
310 };
311 
312 /* in the unified message we add the trailing
313  * stream id since it is the only message
314  * that is defined as a operation error.
315  */
316 struct sctpOpErrorCause{
317   nd_uint16_t cause;
318   nd_uint16_t causeLen;
319 };
320 
321 struct sctpUnifiedOpError{
322   struct sctpChunkDesc uh;
323   struct sctpOpErrorCause c;
324 };
325 
326 struct sctpUnifiedStreamError{
327   struct sctpHeader mh;
328   struct sctpChunkDesc uh;
329   struct sctpOpErrorCause c;
330   nd_uint16_t strmNum;
331   nd_uint16_t reserved;
332 };
333 
334 struct staleCookieMsg{
335   struct sctpHeader mh;
336   struct sctpChunkDesc uh;
337   struct sctpOpErrorCause c;
338   nd_uint32_t moretime;
339 };
340 
341 /* the following is used in all sends
342  * where nothing is needed except the
343  * chunk/type i.e. shutdownAck Abort */
344 
345 struct sctpUnifiedSingleMsg{
346   struct sctpHeader mh;
347   struct sctpChunkDesc uh;
348 };
349 
350 struct sctpDataPart{
351   nd_uint32_t TSN;
352   nd_uint16_t streamId;
353   nd_uint16_t sequence;
354   nd_uint32_t payloadtype;
355 };
356 
357 struct sctpUnifiedDatagram{
358   struct sctpChunkDesc uh;
359   struct sctpDataPart dp;
360 };
361 
362 struct sctpECN_echo{
363   struct sctpChunkDesc uh;
364   nd_uint32_t Lowest_TSN;
365 };
366 
367 
368 struct sctpCWR{
369   struct sctpChunkDesc uh;
370   nd_uint32_t TSN_reduced_at;
371 };
372 
373 static const struct tok ForCES_channels[] = {
374 	{ CHAN_HP, "ForCES HP" },
375 	{ CHAN_MP, "ForCES MP" },
376 	{ CHAN_LP, "ForCES LP" },
377 	{ 0, NULL }
378 };
379 
380 /* data chunk's payload protocol identifiers */
381 
382 #define SCTP_PPID_IUA 1
383 #define SCTP_PPID_M2UA 2
384 #define SCTP_PPID_M3UA 3
385 #define SCTP_PPID_SUA 4
386 #define SCTP_PPID_M2PA 5
387 #define SCTP_PPID_V5UA 6
388 #define SCTP_PPID_H248 7
389 #define SCTP_PPID_BICC 8
390 #define SCTP_PPID_TALI 9
391 #define SCTP_PPID_DUA 10
392 #define SCTP_PPID_ASAP 11
393 #define SCTP_PPID_ENRP 12
394 #define SCTP_PPID_H323 13
395 #define SCTP_PPID_QIPC 14
396 #define SCTP_PPID_SIMCO 15
397 #define SCTP_PPID_DDPSC 16
398 #define SCTP_PPID_DDPSSC 17
399 #define SCTP_PPID_S1AP 18
400 #define SCTP_PPID_RUA 19
401 #define SCTP_PPID_HNBAP 20
402 #define SCTP_PPID_FORCES_HP 21
403 #define SCTP_PPID_FORCES_MP 22
404 #define SCTP_PPID_FORCES_LP 23
405 #define SCTP_PPID_SBC_AP 24
406 #define SCTP_PPID_NBAP 25
407 /* 26 */
408 #define SCTP_PPID_X2AP 27
409 
410 static const struct tok PayloadProto_idents[] = {
411 	{ SCTP_PPID_IUA,    "ISDN Q.921" },
412 	{ SCTP_PPID_M2UA,   "M2UA"   },
413 	{ SCTP_PPID_M3UA,   "M3UA"   },
414 	{ SCTP_PPID_SUA,    "SUA"    },
415 	{ SCTP_PPID_M2PA,   "M2PA"   },
416 	{ SCTP_PPID_V5UA,   "V5.2"   },
417 	{ SCTP_PPID_H248,   "H.248"  },
418 	{ SCTP_PPID_BICC,   "BICC"   },
419 	{ SCTP_PPID_TALI,   "TALI"   },
420 	{ SCTP_PPID_DUA,    "DUA"    },
421 	{ SCTP_PPID_ASAP,   "ASAP"   },
422 	{ SCTP_PPID_ENRP,   "ENRP"   },
423 	{ SCTP_PPID_H323,   "H.323"  },
424 	{ SCTP_PPID_QIPC,   "Q.IPC"  },
425 	{ SCTP_PPID_SIMCO,  "SIMCO"  },
426 	{ SCTP_PPID_DDPSC,  "DDPSC"  },
427 	{ SCTP_PPID_DDPSSC, "DDPSSC" },
428 	{ SCTP_PPID_S1AP,   "S1AP"   },
429 	{ SCTP_PPID_RUA,    "RUA"    },
430 	{ SCTP_PPID_HNBAP,  "HNBAP"  },
431 	{ SCTP_PPID_FORCES_HP, "ForCES HP" },
432 	{ SCTP_PPID_FORCES_MP, "ForCES MP" },
433 	{ SCTP_PPID_FORCES_LP, "ForCES LP" },
434 	{ SCTP_PPID_SBC_AP, "SBc-AP" },
435 	{ SCTP_PPID_NBAP,   "NBAP"   },
436 	/* 26 */
437 	{ SCTP_PPID_X2AP,   "X2AP"   },
438 	{ 0, NULL }
439 };
440 
441 
442 static int
443 isForCES_port(u_short Port)
444 {
445 	if (Port == CHAN_HP)
446 		return 1;
447 	if (Port == CHAN_MP)
448 		return 1;
449 	if (Port == CHAN_LP)
450 		return 1;
451 
452 	return 0;
453 }
454 
455 void
456 sctp_print(netdissect_options *ndo,
457 	   const u_char *bp,        /* beginning of sctp packet */
458 	   const u_char *bp2,       /* beginning of enclosing */
459 	   u_int sctpPacketLength)  /* ip packet */
460 {
461   u_int sctpPacketLengthRemaining;
462   const struct sctpHeader *sctpPktHdr;
463   const struct ip *ip;
464   const struct ip6_hdr *ip6;
465   uint8_t chunkID;
466   u_short sourcePort, destPort;
467   u_int chunkCount;
468   const struct sctpChunkDesc *chunkDescPtr;
469   const char *sep;
470   int isforces = 0;
471 
472   ndo->ndo_protocol = "sctp";
473   if (sctpPacketLength < sizeof(struct sctpHeader))
474     {
475       ND_PRINT("truncated-sctp - %zu bytes missing!",
476                sizeof(struct sctpHeader) - sctpPacketLength);
477       return;
478     }
479   sctpPktHdr = (const struct sctpHeader*) bp;
480   ND_TCHECK_SIZE(sctpPktHdr);
481   sctpPacketLengthRemaining = sctpPacketLength;
482 
483   sourcePort = GET_BE_U_2(sctpPktHdr->source);
484   destPort = GET_BE_U_2(sctpPktHdr->destination);
485 
486   ip = (const struct ip *)bp2;
487   if (IP_V(ip) == 6)
488     ip6 = (const struct ip6_hdr *)bp2;
489   else
490     ip6 = NULL;
491 
492   if (ip6) {
493     ND_PRINT("%s.%u > %s.%u: sctp",
494       GET_IP6ADDR_STRING(ip6->ip6_src),
495       sourcePort,
496       GET_IP6ADDR_STRING(ip6->ip6_dst),
497       destPort);
498   } else {
499     ND_PRINT("%s.%u > %s.%u: sctp",
500       GET_IPADDR_STRING(ip->ip_src),
501       sourcePort,
502       GET_IPADDR_STRING(ip->ip_dst),
503       destPort);
504   }
505 
506   if (isForCES_port(sourcePort)) {
507 	 ND_PRINT("[%s]", tok2str(ForCES_channels, NULL, sourcePort));
508 	 isforces = 1;
509   }
510   if (isForCES_port(destPort)) {
511 	 ND_PRINT("[%s]", tok2str(ForCES_channels, NULL, destPort));
512 	 isforces = 1;
513   }
514 
515   bp += sizeof(struct sctpHeader);
516   sctpPacketLengthRemaining -= sizeof(struct sctpHeader);
517 
518   if (ndo->ndo_vflag >= 2)
519     sep = "\n\t";
520   else
521     sep = " (";
522   /* cycle through all chunks, printing information on each one */
523   for (chunkCount = 0, chunkDescPtr = (const struct sctpChunkDesc *)bp;
524       sctpPacketLengthRemaining != 0;
525       chunkCount++)
526     {
527       uint16_t chunkLength, chunkLengthRemaining;
528       uint16_t align;
529 
530       chunkDescPtr = (const struct sctpChunkDesc *)bp;
531       if (sctpPacketLengthRemaining < sizeof(*chunkDescPtr)) {
532 	ND_PRINT("%s%u) [chunk descriptor cut off at end of packet]", sep, chunkCount+1);
533 	break;
534       }
535       ND_TCHECK_SIZE(chunkDescPtr);
536       chunkLength = GET_BE_U_2(chunkDescPtr->chunkLength);
537       if (chunkLength < sizeof(*chunkDescPtr)) {
538 	ND_PRINT("%s%u) [Bad chunk length %u, < size of chunk descriptor]", sep, chunkCount+1, chunkLength);
539 	break;
540       }
541       chunkLengthRemaining = chunkLength;
542 
543       align = chunkLength % 4;
544       if (align != 0)
545 	align = 4 - align;
546 
547       if (sctpPacketLengthRemaining < align) {
548 	ND_PRINT("%s%u) [Bad chunk length %u, > remaining data in packet]", sep, chunkCount+1, chunkLength);
549 	break;
550       }
551 
552       ND_TCHECK_LEN(bp, chunkLength);
553 
554       bp += sizeof(*chunkDescPtr);
555       sctpPacketLengthRemaining -= sizeof(*chunkDescPtr);
556       chunkLengthRemaining -= sizeof(*chunkDescPtr);
557 
558       ND_PRINT("%s%u) ", sep, chunkCount+1);
559       chunkID = GET_U_1(chunkDescPtr->chunkID);
560       ND_PRINT("[%s] ", tok2str(sctp_chunkid_str, "Unknown chunk type: 0x%x",
561 	       chunkID));
562       switch (chunkID)
563 	{
564 	case SCTP_DATA :
565 	  {
566 	    const struct sctpDataPart *dataHdrPtr;
567 	    uint8_t chunkFlg;
568 	    uint32_t ppid;
569 	    uint16_t payload_size;
570 
571 	    chunkFlg = GET_U_1(chunkDescPtr->chunkFlg);
572 	    if ((chunkFlg & SCTP_DATA_UNORDERED) == SCTP_DATA_UNORDERED)
573 	      ND_PRINT("(U)");
574 
575 	    if ((chunkFlg & SCTP_DATA_FIRST_FRAG) == SCTP_DATA_FIRST_FRAG)
576 	      ND_PRINT("(B)");
577 
578 	    if ((chunkFlg & SCTP_DATA_LAST_FRAG) == SCTP_DATA_LAST_FRAG)
579 	      ND_PRINT("(E)");
580 
581 	    if( ((chunkFlg & SCTP_DATA_UNORDERED) == SCTP_DATA_UNORDERED) ||
582 		((chunkFlg & SCTP_DATA_FIRST_FRAG) == SCTP_DATA_FIRST_FRAG) ||
583 		((chunkFlg & SCTP_DATA_LAST_FRAG) == SCTP_DATA_LAST_FRAG) )
584 	      ND_PRINT(" ");
585 
586 	    if (chunkLengthRemaining < sizeof(*dataHdrPtr)) {
587 		ND_PRINT("bogus chunk length %u]", chunkLength);
588 		return;
589 	    }
590 	    dataHdrPtr=(const struct sctpDataPart*)bp;
591 
592 	    ppid = GET_BE_U_4(dataHdrPtr->payloadtype);
593 	    ND_PRINT("[TSN: %u] ", GET_BE_U_4(dataHdrPtr->TSN));
594 	    ND_PRINT("[SID: %u] ", GET_BE_U_2(dataHdrPtr->streamId));
595 	    ND_PRINT("[SSEQ %u] ", GET_BE_U_2(dataHdrPtr->sequence));
596 	    ND_PRINT("[PPID %s] ",
597 		    tok2str(PayloadProto_idents, "0x%x", ppid));
598 
599 	    if (!isforces) {
600 		isforces = (ppid == SCTP_PPID_FORCES_HP) ||
601 		    (ppid == SCTP_PPID_FORCES_MP) ||
602 		    (ppid == SCTP_PPID_FORCES_LP);
603 	    }
604 
605 	    bp += sizeof(*dataHdrPtr);
606 	    sctpPacketLengthRemaining -= sizeof(*dataHdrPtr);
607 	    chunkLengthRemaining -= sizeof(*dataHdrPtr);
608 	    payload_size = chunkLengthRemaining;
609 	    if (payload_size == 0) {
610 		ND_PRINT("bogus chunk length %u]", chunkLength);
611 		return;
612 	    }
613 
614 	    if (isforces) {
615 		forces_print(ndo, bp, payload_size);
616 		/* ndo_protocol reassignment after forces_print() call */
617 		ndo->ndo_protocol = "sctp";
618 	    } else if (ndo->ndo_vflag >= 2) {	/* if verbose output is specified */
619 					/* at the command line */
620 		switch (ppid) {
621 		case SCTP_PPID_M3UA :
622 			m3ua_print(ndo, bp, payload_size);
623 			/* ndo_protocol reassignment after m3ua_print() call */
624 			ndo->ndo_protocol = "sctp";
625 			break;
626 		default:
627 			ND_PRINT("[Payload");
628 			if (!ndo->ndo_suppress_default_print) {
629 				ND_PRINT(":");
630 				ND_DEFAULTPRINT(bp, payload_size);
631 			}
632 			ND_PRINT("]");
633 			break;
634 		}
635 	    }
636 	    bp += payload_size;
637 	    sctpPacketLengthRemaining -= payload_size;
638 	    chunkLengthRemaining -= payload_size;
639 	    break;
640 	  }
641 	case SCTP_INITIATION :
642 	  {
643 	    const struct sctpInitiation *init;
644 
645 	    if (chunkLengthRemaining < sizeof(*init)) {
646 		ND_PRINT("bogus chunk length %u]", chunkLength);
647 		return;
648 	    }
649 	    init=(const struct sctpInitiation*)bp;
650 	    ND_PRINT("[init tag: %u] ", GET_BE_U_4(init->initTag));
651 	    ND_PRINT("[rwnd: %u] ", GET_BE_U_4(init->rcvWindowCredit));
652 	    ND_PRINT("[OS: %u] ", GET_BE_U_2(init->NumPreopenStreams));
653 	    ND_PRINT("[MIS: %u] ", GET_BE_U_2(init->MaxInboundStreams));
654 	    ND_PRINT("[init TSN: %u] ", GET_BE_U_4(init->initialTSN));
655 	    bp += sizeof(*init);
656 	    sctpPacketLengthRemaining -= sizeof(*init);
657 	    chunkLengthRemaining -= sizeof(*init);
658 
659 #if 0 /* ALC you can add code for optional params here */
660 	    if( chunkLengthRemaining != 0 )
661 	      ND_PRINT(" @@@@@ UNFINISHED @@@@@@%s\n",
662 		     "Optional params present, but not printed.");
663 #endif
664 	    bp += chunkLengthRemaining;
665 	    sctpPacketLengthRemaining -= chunkLengthRemaining;
666 	    chunkLengthRemaining = 0;
667 	    break;
668 	  }
669 	case SCTP_INITIATION_ACK :
670 	  {
671 	    const struct sctpInitiation *init;
672 
673 	    if (chunkLengthRemaining < sizeof(*init)) {
674 		ND_PRINT("bogus chunk length %u]", chunkLength);
675 		return;
676 	    }
677 	    init=(const struct sctpInitiation*)bp;
678 	    ND_PRINT("[init tag: %u] ", GET_BE_U_4(init->initTag));
679 	    ND_PRINT("[rwnd: %u] ", GET_BE_U_4(init->rcvWindowCredit));
680 	    ND_PRINT("[OS: %u] ", GET_BE_U_2(init->NumPreopenStreams));
681 	    ND_PRINT("[MIS: %u] ", GET_BE_U_2(init->MaxInboundStreams));
682 	    ND_PRINT("[init TSN: %u] ", GET_BE_U_4(init->initialTSN));
683 	    bp += sizeof(*init);
684 	    sctpPacketLengthRemaining -= sizeof(*init);
685 	    chunkLengthRemaining -= sizeof(*init);
686 
687 #if 0 /* ALC you can add code for optional params here */
688 	    if( chunkLengthRemaining != 0 )
689 	      ND_PRINT(" @@@@@ UNFINISHED @@@@@@%s\n",
690 		     "Optional params present, but not printed.");
691 #endif
692 	    bp += chunkLengthRemaining;
693 	    sctpPacketLengthRemaining -= chunkLengthRemaining;
694 	    chunkLengthRemaining = 0;
695 	    break;
696 	  }
697 	case SCTP_SELECTIVE_ACK:
698 	  {
699 	    const struct sctpSelectiveAck *sack;
700 	    const struct sctpSelectiveFrag *frag;
701 	    u_int fragNo, tsnNo;
702 	    const u_char *dupTSN;
703 
704 	    if (chunkLengthRemaining < sizeof(*sack)) {
705 	      ND_PRINT("bogus chunk length %u]", chunkLength);
706 	      return;
707 	    }
708 	    sack=(const struct sctpSelectiveAck*)bp;
709 	    ND_PRINT("[cum ack %u] ", GET_BE_U_4(sack->highestConseqTSN));
710 	    ND_PRINT("[a_rwnd %u] ", GET_BE_U_4(sack->updatedRwnd));
711 	    ND_PRINT("[#gap acks %u] ", GET_BE_U_2(sack->numberOfdesc));
712 	    ND_PRINT("[#dup tsns %u] ", GET_BE_U_2(sack->numDupTsns));
713 	    bp += sizeof(*sack);
714 	    sctpPacketLengthRemaining -= sizeof(*sack);
715 	    chunkLengthRemaining -= sizeof(*sack);
716 
717 
718 	    /* print gaps */
719 	    for (fragNo=0;
720 		 chunkLengthRemaining != 0 && fragNo < GET_BE_U_2(sack->numberOfdesc);
721 		 bp += sizeof(*frag), sctpPacketLengthRemaining -= sizeof(*frag), chunkLengthRemaining -= sizeof(*frag), fragNo++) {
722 	      if (chunkLengthRemaining < sizeof(*frag)) {
723 		ND_PRINT("bogus chunk length %u]", chunkLength);
724 		return;
725 	      }
726 	      frag = (const struct sctpSelectiveFrag *)bp;
727 	      ND_PRINT("\n\t\t[gap ack block #%u: start = %u, end = %u] ",
728 		     fragNo+1,
729 		     GET_BE_U_4(sack->highestConseqTSN) + GET_BE_U_2(frag->fragmentStart),
730 		     GET_BE_U_4(sack->highestConseqTSN) + GET_BE_U_2(frag->fragmentEnd));
731 	    }
732 
733 	    /* print duplicate TSNs */
734 	    for (tsnNo=0;
735 		 chunkLengthRemaining != 0 && tsnNo<GET_BE_U_2(sack->numDupTsns);
736 		 bp += 4, sctpPacketLengthRemaining -= 4, chunkLengthRemaining -= 4, tsnNo++) {
737 	      if (chunkLengthRemaining < 4) {
738 		ND_PRINT("bogus chunk length %u]", chunkLength);
739 		return;
740 	      }
741 	      dupTSN = (const u_char *)bp;
742 	      ND_PRINT("\n\t\t[dup TSN #%u: %u] ", tsnNo+1,
743 		       GET_BE_U_4(dupTSN));
744 	    }
745 	    break;
746 	  }
747 	default :
748 	  {
749 	    bp += chunkLengthRemaining;
750 	    sctpPacketLengthRemaining -= chunkLengthRemaining;
751 	    chunkLengthRemaining = 0;
752 	    break;
753 	  }
754 	}
755 
756       /*
757        * Any extra stuff at the end of the chunk?
758        * XXX - report this?
759        */
760       bp += chunkLengthRemaining;
761       sctpPacketLengthRemaining -= chunkLengthRemaining;
762 
763       if (ndo->ndo_vflag < 2)
764 	sep = ", (";
765 
766       if (align != 0) {
767 	/*
768 	 * Fail if the alignment padding isn't in the captured data.
769 	 * Otherwise, skip it.
770 	 */
771 	ND_TCHECK_LEN(bp, align);
772 	bp += align;
773 	sctpPacketLengthRemaining -= align;
774       }
775     }
776     return;
777 
778 trunc:
779     nd_print_trunc(ndo);
780 }
781