xref: /linux/tools/testing/selftests/net/ioam6_parser.c (revision 2697b79a469b68e3ad3640f55284359c1396278d)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Author: Justin Iurman (justin.iurman@uliege.be)
4  *
5  * IOAM tester for IPv6, see ioam6.sh for details on each test case.
6  */
7 #include <arpa/inet.h>
8 #include <errno.h>
9 #include <limits.h>
10 #include <linux/const.h>
11 #include <linux/ioam6.h>
12 #include <linux/ipv6.h>
13 #include <stdlib.h>
14 #include <string.h>
15 #include <unistd.h>
16 
17 struct ioam_config {
18 	__u32 id;
19 	__u64 wide;
20 	__u16 ingr_id;
21 	__u16 egr_id;
22 	__u32 ingr_wide;
23 	__u32 egr_wide;
24 	__u32 ns_data;
25 	__u64 ns_wide;
26 	__u32 sc_id;
27 	__u8 hlim;
28 	char *sc_data;
29 };
30 
31 /*
32  * Be careful if you modify structs below - everything MUST be kept synchronized
33  * with configurations inside ioam6.sh and always reflect the same.
34  */
35 
36 static struct ioam_config node1 = {
37 	.id = 1,
38 	.wide = 11111111,
39 	.ingr_id = 0xffff, /* default value */
40 	.egr_id = 101,
41 	.ingr_wide = 0xffffffff, /* default value */
42 	.egr_wide = 101101,
43 	.ns_data = 0xdeadbee0,
44 	.ns_wide = 0xcafec0caf00dc0de,
45 	.sc_id = 777,
46 	.sc_data = "something that will be 4n-aligned",
47 	.hlim = 64,
48 };
49 
50 static struct ioam_config node2 = {
51 	.id = 2,
52 	.wide = 22222222,
53 	.ingr_id = 201,
54 	.egr_id = 202,
55 	.ingr_wide = 201201,
56 	.egr_wide = 202202,
57 	.ns_data = 0xdeadbee1,
58 	.ns_wide = 0xcafec0caf11dc0de,
59 	.sc_id = 666,
60 	.sc_data = "Hello there -Obi",
61 	.hlim = 63,
62 };
63 
64 static struct ioam_config node3 = {
65 	.id = 3,
66 	.wide = 33333333,
67 	.ingr_id = 301,
68 	.egr_id = 0xffff, /* default value */
69 	.ingr_wide = 301301,
70 	.egr_wide = 0xffffffff, /* default value */
71 	.ns_data = 0xdeadbee2,
72 	.ns_wide = 0xcafec0caf22dc0de,
73 	.sc_id = 0xffffff, /* default value */
74 	.sc_data = NULL,
75 	.hlim = 62,
76 };
77 
78 enum {
79 	/**********
80 	 * OUTPUT *
81 	 **********/
82 	TEST_OUT_UNDEF_NS,
83 	TEST_OUT_NO_ROOM,
84 	TEST_OUT_BIT0,
85 	TEST_OUT_BIT1,
86 	TEST_OUT_BIT2,
87 	TEST_OUT_BIT3,
88 	TEST_OUT_BIT4,
89 	TEST_OUT_BIT5,
90 	TEST_OUT_BIT6,
91 	TEST_OUT_BIT7,
92 	TEST_OUT_BIT8,
93 	TEST_OUT_BIT9,
94 	TEST_OUT_BIT10,
95 	TEST_OUT_BIT11,
96 	TEST_OUT_BIT22,
97 	TEST_OUT_FULL_SUPP_TRACE,
98 
99 	/*********
100 	 * INPUT *
101 	 *********/
102 	TEST_IN_UNDEF_NS,
103 	TEST_IN_NO_ROOM,
104 	TEST_IN_OFLAG,
105 	TEST_IN_BIT0,
106 	TEST_IN_BIT1,
107 	TEST_IN_BIT2,
108 	TEST_IN_BIT3,
109 	TEST_IN_BIT4,
110 	TEST_IN_BIT5,
111 	TEST_IN_BIT6,
112 	TEST_IN_BIT7,
113 	TEST_IN_BIT8,
114 	TEST_IN_BIT9,
115 	TEST_IN_BIT10,
116 	TEST_IN_BIT11,
117 	TEST_IN_BIT22,
118 	TEST_IN_FULL_SUPP_TRACE,
119 
120 	/**********
121 	 * GLOBAL *
122 	 **********/
123 	TEST_FWD_FULL_SUPP_TRACE,
124 
125 	__TEST_MAX,
126 };
127 
128 static int check_ioam_header(int tid, struct ioam6_trace_hdr *ioam6h,
129 			     __u32 trace_type, __u16 ioam_ns)
130 {
131 	if (__be16_to_cpu(ioam6h->namespace_id) != ioam_ns ||
132 	    __be32_to_cpu(ioam6h->type_be32) != (trace_type << 8))
133 		return 1;
134 
135 	switch (tid) {
136 	case TEST_OUT_UNDEF_NS:
137 	case TEST_IN_UNDEF_NS:
138 		return ioam6h->overflow ||
139 		       ioam6h->nodelen != 1 ||
140 		       ioam6h->remlen != 1;
141 
142 	case TEST_OUT_NO_ROOM:
143 	case TEST_IN_NO_ROOM:
144 	case TEST_IN_OFLAG:
145 		return !ioam6h->overflow ||
146 		       ioam6h->nodelen != 2 ||
147 		       ioam6h->remlen != 1;
148 
149 	case TEST_OUT_BIT0:
150 	case TEST_IN_BIT0:
151 	case TEST_OUT_BIT1:
152 	case TEST_IN_BIT1:
153 	case TEST_OUT_BIT2:
154 	case TEST_IN_BIT2:
155 	case TEST_OUT_BIT3:
156 	case TEST_IN_BIT3:
157 	case TEST_OUT_BIT4:
158 	case TEST_IN_BIT4:
159 	case TEST_OUT_BIT5:
160 	case TEST_IN_BIT5:
161 	case TEST_OUT_BIT6:
162 	case TEST_IN_BIT6:
163 	case TEST_OUT_BIT7:
164 	case TEST_IN_BIT7:
165 	case TEST_OUT_BIT11:
166 	case TEST_IN_BIT11:
167 		return ioam6h->overflow ||
168 		       ioam6h->nodelen != 1 ||
169 		       ioam6h->remlen;
170 
171 	case TEST_OUT_BIT8:
172 	case TEST_IN_BIT8:
173 	case TEST_OUT_BIT9:
174 	case TEST_IN_BIT9:
175 	case TEST_OUT_BIT10:
176 	case TEST_IN_BIT10:
177 		return ioam6h->overflow ||
178 		       ioam6h->nodelen != 2 ||
179 		       ioam6h->remlen;
180 
181 	case TEST_OUT_BIT22:
182 	case TEST_IN_BIT22:
183 		return ioam6h->overflow ||
184 		       ioam6h->nodelen ||
185 		       ioam6h->remlen;
186 
187 	case TEST_OUT_FULL_SUPP_TRACE:
188 	case TEST_IN_FULL_SUPP_TRACE:
189 	case TEST_FWD_FULL_SUPP_TRACE:
190 		return ioam6h->overflow ||
191 		       ioam6h->nodelen != 15 ||
192 		       ioam6h->remlen;
193 
194 	default:
195 		break;
196 	}
197 
198 	return 1;
199 }
200 
201 static int check_ioam6_data(__u8 **p, struct ioam6_trace_hdr *ioam6h,
202 			    const struct ioam_config cnf)
203 {
204 	unsigned int len;
205 	__u8 aligned;
206 	__u64 raw64;
207 	__u32 raw32;
208 
209 	if (ioam6h->type.bit0) {
210 		raw32 = __be32_to_cpu(*((__u32 *)*p));
211 		if (cnf.hlim != (raw32 >> 24) || cnf.id != (raw32 & 0xffffff))
212 			return 1;
213 		*p += sizeof(__u32);
214 	}
215 
216 	if (ioam6h->type.bit1) {
217 		raw32 = __be32_to_cpu(*((__u32 *)*p));
218 		if (cnf.ingr_id != (raw32 >> 16) ||
219 		    cnf.egr_id != (raw32 & 0xffff))
220 			return 1;
221 		*p += sizeof(__u32);
222 	}
223 
224 	if (ioam6h->type.bit2)
225 		*p += sizeof(__u32);
226 
227 	if (ioam6h->type.bit3)
228 		*p += sizeof(__u32);
229 
230 	if (ioam6h->type.bit4) {
231 		if (__be32_to_cpu(*((__u32 *)*p)) != 0xffffffff)
232 			return 1;
233 		*p += sizeof(__u32);
234 	}
235 
236 	if (ioam6h->type.bit5) {
237 		if (__be32_to_cpu(*((__u32 *)*p)) != cnf.ns_data)
238 			return 1;
239 		*p += sizeof(__u32);
240 	}
241 
242 	if (ioam6h->type.bit6)
243 		*p += sizeof(__u32);
244 
245 	if (ioam6h->type.bit7) {
246 		if (__be32_to_cpu(*((__u32 *)*p)) != 0xffffffff)
247 			return 1;
248 		*p += sizeof(__u32);
249 	}
250 
251 	if (ioam6h->type.bit8) {
252 		raw64 = __be64_to_cpu(*((__u64 *)*p));
253 		if (cnf.hlim != (raw64 >> 56) ||
254 		    cnf.wide != (raw64 & 0xffffffffffffff))
255 			return 1;
256 		*p += sizeof(__u64);
257 	}
258 
259 	if (ioam6h->type.bit9) {
260 		if (__be32_to_cpu(*((__u32 *)*p)) != cnf.ingr_wide)
261 			return 1;
262 		*p += sizeof(__u32);
263 
264 		if (__be32_to_cpu(*((__u32 *)*p)) != cnf.egr_wide)
265 			return 1;
266 		*p += sizeof(__u32);
267 	}
268 
269 	if (ioam6h->type.bit10) {
270 		if (__be64_to_cpu(*((__u64 *)*p)) != cnf.ns_wide)
271 			return 1;
272 		*p += sizeof(__u64);
273 	}
274 
275 	if (ioam6h->type.bit11) {
276 		if (__be32_to_cpu(*((__u32 *)*p)) != 0xffffffff)
277 			return 1;
278 		*p += sizeof(__u32);
279 	}
280 
281 	if (ioam6h->type.bit12) {
282 		if (__be32_to_cpu(*((__u32 *)*p)) != 0xffffffff)
283 			return 1;
284 		*p += sizeof(__u32);
285 	}
286 
287 	if (ioam6h->type.bit13) {
288 		if (__be32_to_cpu(*((__u32 *)*p)) != 0xffffffff)
289 			return 1;
290 		*p += sizeof(__u32);
291 	}
292 
293 	if (ioam6h->type.bit14) {
294 		if (__be32_to_cpu(*((__u32 *)*p)) != 0xffffffff)
295 			return 1;
296 		*p += sizeof(__u32);
297 	}
298 
299 	if (ioam6h->type.bit15) {
300 		if (__be32_to_cpu(*((__u32 *)*p)) != 0xffffffff)
301 			return 1;
302 		*p += sizeof(__u32);
303 	}
304 
305 	if (ioam6h->type.bit16) {
306 		if (__be32_to_cpu(*((__u32 *)*p)) != 0xffffffff)
307 			return 1;
308 		*p += sizeof(__u32);
309 	}
310 
311 	if (ioam6h->type.bit17) {
312 		if (__be32_to_cpu(*((__u32 *)*p)) != 0xffffffff)
313 			return 1;
314 		*p += sizeof(__u32);
315 	}
316 
317 	if (ioam6h->type.bit18) {
318 		if (__be32_to_cpu(*((__u32 *)*p)) != 0xffffffff)
319 			return 1;
320 		*p += sizeof(__u32);
321 	}
322 
323 	if (ioam6h->type.bit19) {
324 		if (__be32_to_cpu(*((__u32 *)*p)) != 0xffffffff)
325 			return 1;
326 		*p += sizeof(__u32);
327 	}
328 
329 	if (ioam6h->type.bit20) {
330 		if (__be32_to_cpu(*((__u32 *)*p)) != 0xffffffff)
331 			return 1;
332 		*p += sizeof(__u32);
333 	}
334 
335 	if (ioam6h->type.bit21) {
336 		if (__be32_to_cpu(*((__u32 *)*p)) != 0xffffffff)
337 			return 1;
338 		*p += sizeof(__u32);
339 	}
340 
341 	if (ioam6h->type.bit22) {
342 		len = cnf.sc_data ? strlen(cnf.sc_data) : 0;
343 		aligned = cnf.sc_data ? __ALIGN_KERNEL(len, 4) : 0;
344 
345 		raw32 = __be32_to_cpu(*((__u32 *)*p));
346 		if (aligned != (raw32 >> 24) * 4 ||
347 		    cnf.sc_id != (raw32 & 0xffffff))
348 			return 1;
349 		*p += sizeof(__u32);
350 
351 		if (cnf.sc_data) {
352 			if (strncmp((char *)*p, cnf.sc_data, len))
353 				return 1;
354 
355 			*p += len;
356 			aligned -= len;
357 
358 			while (aligned--) {
359 				if (**p != '\0')
360 					return 1;
361 				*p += sizeof(__u8);
362 			}
363 		}
364 	}
365 
366 	return 0;
367 }
368 
369 static int check_ioam_header_and_data(int tid, struct ioam6_trace_hdr *ioam6h,
370 				      __u32 trace_type, __u16 ioam_ns)
371 {
372 	__u8 *p;
373 
374 	if (check_ioam_header(tid, ioam6h, trace_type, ioam_ns))
375 		return 1;
376 
377 	p = ioam6h->data + ioam6h->remlen * 4;
378 
379 	switch (tid) {
380 	case TEST_OUT_BIT0:
381 	case TEST_OUT_BIT1:
382 	case TEST_OUT_BIT2:
383 	case TEST_OUT_BIT3:
384 	case TEST_OUT_BIT4:
385 	case TEST_OUT_BIT5:
386 	case TEST_OUT_BIT6:
387 	case TEST_OUT_BIT7:
388 	case TEST_OUT_BIT8:
389 	case TEST_OUT_BIT9:
390 	case TEST_OUT_BIT10:
391 	case TEST_OUT_BIT11:
392 	case TEST_OUT_BIT22:
393 	case TEST_OUT_FULL_SUPP_TRACE:
394 		return check_ioam6_data(&p, ioam6h, node1);
395 
396 	case TEST_IN_BIT0:
397 	case TEST_IN_BIT1:
398 	case TEST_IN_BIT2:
399 	case TEST_IN_BIT3:
400 	case TEST_IN_BIT4:
401 	case TEST_IN_BIT5:
402 	case TEST_IN_BIT6:
403 	case TEST_IN_BIT7:
404 	case TEST_IN_BIT8:
405 	case TEST_IN_BIT9:
406 	case TEST_IN_BIT10:
407 	case TEST_IN_BIT11:
408 	case TEST_IN_BIT22:
409 	case TEST_IN_FULL_SUPP_TRACE:
410 	{
411 		__u32 tmp32 = node2.egr_wide;
412 		__u16 tmp16 = node2.egr_id;
413 		int res;
414 
415 		node2.egr_id = 0xffff;
416 		node2.egr_wide = 0xffffffff;
417 
418 		res = check_ioam6_data(&p, ioam6h, node2);
419 
420 		node2.egr_id = tmp16;
421 		node2.egr_wide = tmp32;
422 
423 		return res;
424 	}
425 
426 	case TEST_FWD_FULL_SUPP_TRACE:
427 		if (check_ioam6_data(&p, ioam6h, node3))
428 			return 1;
429 		if (check_ioam6_data(&p, ioam6h, node2))
430 			return 1;
431 		return check_ioam6_data(&p, ioam6h, node1);
432 
433 	default:
434 		break;
435 	}
436 
437 	return 1;
438 }
439 
440 static int str2id(const char *tname)
441 {
442 	if (!strcmp("out_undef_ns", tname))
443 		return TEST_OUT_UNDEF_NS;
444 	if (!strcmp("out_no_room", tname))
445 		return TEST_OUT_NO_ROOM;
446 	if (!strcmp("out_bit0", tname))
447 		return TEST_OUT_BIT0;
448 	if (!strcmp("out_bit1", tname))
449 		return TEST_OUT_BIT1;
450 	if (!strcmp("out_bit2", tname))
451 		return TEST_OUT_BIT2;
452 	if (!strcmp("out_bit3", tname))
453 		return TEST_OUT_BIT3;
454 	if (!strcmp("out_bit4", tname))
455 		return TEST_OUT_BIT4;
456 	if (!strcmp("out_bit5", tname))
457 		return TEST_OUT_BIT5;
458 	if (!strcmp("out_bit6", tname))
459 		return TEST_OUT_BIT6;
460 	if (!strcmp("out_bit7", tname))
461 		return TEST_OUT_BIT7;
462 	if (!strcmp("out_bit8", tname))
463 		return TEST_OUT_BIT8;
464 	if (!strcmp("out_bit9", tname))
465 		return TEST_OUT_BIT9;
466 	if (!strcmp("out_bit10", tname))
467 		return TEST_OUT_BIT10;
468 	if (!strcmp("out_bit11", tname))
469 		return TEST_OUT_BIT11;
470 	if (!strcmp("out_bit22", tname))
471 		return TEST_OUT_BIT22;
472 	if (!strcmp("out_full_supp_trace", tname))
473 		return TEST_OUT_FULL_SUPP_TRACE;
474 	if (!strcmp("in_undef_ns", tname))
475 		return TEST_IN_UNDEF_NS;
476 	if (!strcmp("in_no_room", tname))
477 		return TEST_IN_NO_ROOM;
478 	if (!strcmp("in_oflag", tname))
479 		return TEST_IN_OFLAG;
480 	if (!strcmp("in_bit0", tname))
481 		return TEST_IN_BIT0;
482 	if (!strcmp("in_bit1", tname))
483 		return TEST_IN_BIT1;
484 	if (!strcmp("in_bit2", tname))
485 		return TEST_IN_BIT2;
486 	if (!strcmp("in_bit3", tname))
487 		return TEST_IN_BIT3;
488 	if (!strcmp("in_bit4", tname))
489 		return TEST_IN_BIT4;
490 	if (!strcmp("in_bit5", tname))
491 		return TEST_IN_BIT5;
492 	if (!strcmp("in_bit6", tname))
493 		return TEST_IN_BIT6;
494 	if (!strcmp("in_bit7", tname))
495 		return TEST_IN_BIT7;
496 	if (!strcmp("in_bit8", tname))
497 		return TEST_IN_BIT8;
498 	if (!strcmp("in_bit9", tname))
499 		return TEST_IN_BIT9;
500 	if (!strcmp("in_bit10", tname))
501 		return TEST_IN_BIT10;
502 	if (!strcmp("in_bit11", tname))
503 		return TEST_IN_BIT11;
504 	if (!strcmp("in_bit22", tname))
505 		return TEST_IN_BIT22;
506 	if (!strcmp("in_full_supp_trace", tname))
507 		return TEST_IN_FULL_SUPP_TRACE;
508 	if (!strcmp("fwd_full_supp_trace", tname))
509 		return TEST_FWD_FULL_SUPP_TRACE;
510 
511 	return -1;
512 }
513 
514 static int get_u32(__u32 *val, const char *arg, int base)
515 {
516 	unsigned long res;
517 	char *ptr;
518 
519 	if (!arg || !*arg)
520 		return -1;
521 	res = strtoul(arg, &ptr, base);
522 
523 	if (!ptr || ptr == arg || *ptr)
524 		return -1;
525 
526 	if (res == ULONG_MAX && errno == ERANGE)
527 		return -1;
528 
529 	if (res > 0xFFFFFFFFUL)
530 		return -1;
531 
532 	*val = res;
533 	return 0;
534 }
535 
536 static int get_u16(__u16 *val, const char *arg, int base)
537 {
538 	unsigned long res;
539 	char *ptr;
540 
541 	if (!arg || !*arg)
542 		return -1;
543 	res = strtoul(arg, &ptr, base);
544 
545 	if (!ptr || ptr == arg || *ptr)
546 		return -1;
547 
548 	if (res == ULONG_MAX && errno == ERANGE)
549 		return -1;
550 
551 	if (res > 0xFFFFUL)
552 		return -1;
553 
554 	*val = res;
555 	return 0;
556 }
557 
558 static int (*func[__TEST_MAX])(int, struct ioam6_trace_hdr *, __u32, __u16) = {
559 	[TEST_OUT_UNDEF_NS]		= check_ioam_header,
560 	[TEST_OUT_NO_ROOM]		= check_ioam_header,
561 	[TEST_OUT_BIT0]		= check_ioam_header_and_data,
562 	[TEST_OUT_BIT1]		= check_ioam_header_and_data,
563 	[TEST_OUT_BIT2]		= check_ioam_header_and_data,
564 	[TEST_OUT_BIT3]		= check_ioam_header_and_data,
565 	[TEST_OUT_BIT4]		= check_ioam_header_and_data,
566 	[TEST_OUT_BIT5]		= check_ioam_header_and_data,
567 	[TEST_OUT_BIT6]		= check_ioam_header_and_data,
568 	[TEST_OUT_BIT7]		= check_ioam_header_and_data,
569 	[TEST_OUT_BIT8]		= check_ioam_header_and_data,
570 	[TEST_OUT_BIT9]		= check_ioam_header_and_data,
571 	[TEST_OUT_BIT10]		= check_ioam_header_and_data,
572 	[TEST_OUT_BIT11]		= check_ioam_header_and_data,
573 	[TEST_OUT_BIT22]		= check_ioam_header_and_data,
574 	[TEST_OUT_FULL_SUPP_TRACE]	= check_ioam_header_and_data,
575 	[TEST_IN_UNDEF_NS]		= check_ioam_header,
576 	[TEST_IN_NO_ROOM]		= check_ioam_header,
577 	[TEST_IN_OFLAG]		= check_ioam_header,
578 	[TEST_IN_BIT0]			= check_ioam_header_and_data,
579 	[TEST_IN_BIT1]			= check_ioam_header_and_data,
580 	[TEST_IN_BIT2]			= check_ioam_header_and_data,
581 	[TEST_IN_BIT3]			= check_ioam_header_and_data,
582 	[TEST_IN_BIT4]			= check_ioam_header_and_data,
583 	[TEST_IN_BIT5]			= check_ioam_header_and_data,
584 	[TEST_IN_BIT6]			= check_ioam_header_and_data,
585 	[TEST_IN_BIT7]			= check_ioam_header_and_data,
586 	[TEST_IN_BIT8]			= check_ioam_header_and_data,
587 	[TEST_IN_BIT9]			= check_ioam_header_and_data,
588 	[TEST_IN_BIT10]		= check_ioam_header_and_data,
589 	[TEST_IN_BIT11]		= check_ioam_header_and_data,
590 	[TEST_IN_BIT22]		= check_ioam_header_and_data,
591 	[TEST_IN_FULL_SUPP_TRACE]	= check_ioam_header_and_data,
592 	[TEST_FWD_FULL_SUPP_TRACE]	= check_ioam_header_and_data,
593 };
594 
595 int main(int argc, char **argv)
596 {
597 	int fd, size, hoplen, tid, ret = 1, on = 1;
598 	struct ioam6_hdr *opt;
599 	struct cmsghdr *cmsg;
600 	struct msghdr msg;
601 	struct iovec iov;
602 	__u8 buffer[512];
603 	__u32 tr_type;
604 	__u16 ioam_ns;
605 	__u8 *ptr;
606 
607 	if (argc != 5)
608 		goto out;
609 
610 	tid = str2id(argv[1]);
611 	if (tid < 0 || !func[tid])
612 		goto out;
613 
614 	if (get_u32(&tr_type, argv[2], 16) ||
615 	    get_u16(&ioam_ns, argv[3], 0))
616 		goto out;
617 
618 	fd = socket(PF_INET6, SOCK_RAW,
619 		    !strcmp(argv[4], "encap") ? IPPROTO_IPV6 : IPPROTO_ICMPV6);
620 	if (fd < 0)
621 		goto out;
622 
623 	setsockopt(fd, IPPROTO_IPV6, IPV6_RECVHOPOPTS,  &on, sizeof(on));
624 
625 	iov.iov_len = 1;
626 	iov.iov_base = malloc(CMSG_SPACE(sizeof(buffer)));
627 	if (!iov.iov_base)
628 		goto close;
629 recv:
630 	memset(&msg, 0, sizeof(msg));
631 	msg.msg_iov = &iov;
632 	msg.msg_iovlen = 1;
633 	msg.msg_control = buffer;
634 	msg.msg_controllen = CMSG_SPACE(sizeof(buffer));
635 
636 	size = recvmsg(fd, &msg, 0);
637 	if (size <= 0)
638 		goto close;
639 
640 	for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
641 		if (cmsg->cmsg_level != IPPROTO_IPV6 ||
642 		    cmsg->cmsg_type != IPV6_HOPOPTS ||
643 		    cmsg->cmsg_len < sizeof(struct ipv6_hopopt_hdr))
644 			continue;
645 
646 		ptr = (__u8 *)CMSG_DATA(cmsg);
647 
648 		hoplen = (ptr[1] + 1) << 3;
649 		ptr += sizeof(struct ipv6_hopopt_hdr);
650 
651 		while (hoplen > 0) {
652 			opt = (struct ioam6_hdr *)ptr;
653 
654 			if (opt->opt_type == IPV6_TLV_IOAM &&
655 			    opt->type == IOAM6_TYPE_PREALLOC) {
656 				ptr += sizeof(*opt);
657 				ret = func[tid](tid,
658 						(struct ioam6_trace_hdr *)ptr,
659 						tr_type, ioam_ns);
660 				goto close;
661 			}
662 
663 			ptr += opt->opt_len + 2;
664 			hoplen -= opt->opt_len + 2;
665 		}
666 	}
667 
668 	goto recv;
669 close:
670 	free(iov.iov_base);
671 	close(fd);
672 out:
673 	return ret;
674 }
675