xref: /freebsd/contrib/tcpdump/print-esp.c (revision f0cfa1b168014f56c02b83e5f28412cc5f78d117)
1 /*	$NetBSD: print-ah.c,v 1.4 1996/05/20 00:41:16 fvdl Exp $	*/
2 
3 /*
4  * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that: (1) source code distributions
9  * retain the above copyright notice and this paragraph in its entirety, (2)
10  * distributions including binary code include the above copyright notice and
11  * this paragraph in its entirety in the documentation or other materials
12  * provided with the distribution, and (3) all advertising materials mentioning
13  * features or use of this software display the following acknowledgement:
14  * ``This product includes software developed by the University of California,
15  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
16  * the University nor the names of its contributors may be used to endorse
17  * or promote products derived from this software without specific prior
18  * written permission.
19  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
20  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
21  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
22  */
23 
24 /* \summary: IPSEC Encapsulating Security Payload (ESP) printer */
25 
26 #ifdef HAVE_CONFIG_H
27 #include "config.h"
28 #endif
29 
30 #include <netdissect-stdinc.h>
31 
32 #include <string.h>
33 #include <stdlib.h>
34 
35 /* Any code in this file that depends on HAVE_LIBCRYPTO depends on
36  * HAVE_OPENSSL_EVP_H too. Undefining the former when the latter isn't defined
37  * is the simplest way of handling the dependency.
38  */
39 #ifdef HAVE_LIBCRYPTO
40 #ifdef HAVE_OPENSSL_EVP_H
41 #include <openssl/evp.h>
42 #else
43 #undef HAVE_LIBCRYPTO
44 #endif
45 #endif
46 
47 #include "netdissect.h"
48 #include "strtoaddr.h"
49 #include "extract.h"
50 
51 #include "ascii_strcasecmp.h"
52 
53 #include "ip.h"
54 #include "ip6.h"
55 
56 /*
57  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
58  * All rights reserved.
59  *
60  * Redistribution and use in source and binary forms, with or without
61  * modification, are permitted provided that the following conditions
62  * are met:
63  * 1. Redistributions of source code must retain the above copyright
64  *    notice, this list of conditions and the following disclaimer.
65  * 2. Redistributions in binary form must reproduce the above copyright
66  *    notice, this list of conditions and the following disclaimer in the
67  *    documentation and/or other materials provided with the distribution.
68  * 3. Neither the name of the project nor the names of its contributors
69  *    may be used to endorse or promote products derived from this software
70  *    without specific prior written permission.
71  *
72  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
73  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
74  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
75  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
76  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
77  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
78  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
79  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
80  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
81  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
82  * SUCH DAMAGE.
83  */
84 
85 /*
86  * RFC1827/2406 Encapsulated Security Payload.
87  */
88 
89 struct newesp {
90 	uint32_t	esp_spi;	/* ESP */
91 	uint32_t	esp_seq;	/* Sequence number */
92 	/*variable size*/		/* (IV and) Payload data */
93 	/*variable size*/		/* padding */
94 	/*8bit*/			/* pad size */
95 	/*8bit*/			/* next header */
96 	/*8bit*/			/* next header */
97 	/*variable size, 32bit bound*/	/* Authentication data */
98 };
99 
100 #ifdef HAVE_LIBCRYPTO
101 union inaddr_u {
102 	struct in_addr in4;
103 	struct in6_addr in6;
104 };
105 struct sa_list {
106 	struct sa_list	*next;
107 	u_int		daddr_version;
108 	union inaddr_u	daddr;
109 	uint32_t	spi;          /* if == 0, then IKEv2 */
110 	int             initiator;
111 	u_char          spii[8];      /* for IKEv2 */
112 	u_char          spir[8];
113 	const EVP_CIPHER *evp;
114 	int		ivlen;
115 	int		authlen;
116 	u_char          authsecret[256];
117 	int             authsecret_len;
118 	u_char		secret[256];  /* is that big enough for all secrets? */
119 	int		secretlen;
120 };
121 
122 #ifndef HAVE_EVP_CIPHER_CTX_NEW
123 /*
124  * Allocate an EVP_CIPHER_CTX.
125  * Used if we have an older version of OpenSSL that doesn't provide
126  * routines to allocate and free them.
127  */
128 static EVP_CIPHER_CTX *
129 EVP_CIPHER_CTX_new(void)
130 {
131 	EVP_CIPHER_CTX *ctx;
132 
133 	ctx = malloc(sizeof(*ctx));
134 	if (ctx == NULL)
135 		return (NULL);
136 	memset(ctx, 0, sizeof(*ctx));
137 	return (ctx);
138 }
139 
140 static void
141 EVP_CIPHER_CTX_free(EVP_CIPHER_CTX *ctx)
142 {
143 	EVP_CIPHER_CTX_cleanup(ctx);
144 	free(ctx);
145 }
146 #endif
147 
148 /*
149  * this will adjust ndo_packetp and ndo_snapend to new buffer!
150  */
151 USES_APPLE_DEPRECATED_API
152 int esp_print_decrypt_buffer_by_ikev2(netdissect_options *ndo,
153 				      int initiator,
154 				      u_char spii[8], u_char spir[8],
155 				      const u_char *buf, const u_char *end)
156 {
157 	struct sa_list *sa;
158 	const u_char *iv;
159 	int len;
160 	EVP_CIPHER_CTX *ctx;
161 
162 	/* initiator arg is any non-zero value */
163 	if(initiator) initiator=1;
164 
165 	/* see if we can find the SA, and if so, decode it */
166 	for (sa = ndo->ndo_sa_list_head; sa != NULL; sa = sa->next) {
167 		if (sa->spi == 0
168 		    && initiator == sa->initiator
169 		    && memcmp(spii, sa->spii, 8) == 0
170 		    && memcmp(spir, sa->spir, 8) == 0)
171 			break;
172 	}
173 
174 	if(sa == NULL) return 0;
175 	if(sa->evp == NULL) return 0;
176 
177 	/*
178 	 * remove authenticator, and see if we still have something to
179 	 * work with
180 	 */
181 	end = end - sa->authlen;
182 	iv  = buf;
183 	buf = buf + sa->ivlen;
184 	len = end-buf;
185 
186 	if(end <= buf) return 0;
187 
188 	ctx = EVP_CIPHER_CTX_new();
189 	if (ctx == NULL)
190 		return 0;
191 	if (EVP_CipherInit(ctx, sa->evp, sa->secret, NULL, 0) < 0)
192 		(*ndo->ndo_warning)(ndo, "espkey init failed");
193 	EVP_CipherInit(ctx, NULL, NULL, iv, 0);
194 	EVP_Cipher(ctx, __DECONST(u_char *, buf), buf, len);
195 	EVP_CIPHER_CTX_free(ctx);
196 
197 	ndo->ndo_packetp = buf;
198 	ndo->ndo_snapend = end;
199 
200 	return 1;
201 
202 }
203 USES_APPLE_RST
204 
205 static void esp_print_addsa(netdissect_options *ndo,
206 			    struct sa_list *sa, int sa_def)
207 {
208 	/* copy the "sa" */
209 
210 	struct sa_list *nsa;
211 
212 	nsa = (struct sa_list *)malloc(sizeof(struct sa_list));
213 	if (nsa == NULL)
214 		(*ndo->ndo_error)(ndo, "ran out of memory to allocate sa structure");
215 
216 	*nsa = *sa;
217 
218 	if (sa_def)
219 		ndo->ndo_sa_default = nsa;
220 
221 	nsa->next = ndo->ndo_sa_list_head;
222 	ndo->ndo_sa_list_head = nsa;
223 }
224 
225 
226 static u_int hexdigit(netdissect_options *ndo, char hex)
227 {
228 	if (hex >= '0' && hex <= '9')
229 		return (hex - '0');
230 	else if (hex >= 'A' && hex <= 'F')
231 		return (hex - 'A' + 10);
232 	else if (hex >= 'a' && hex <= 'f')
233 		return (hex - 'a' + 10);
234 	else {
235 		(*ndo->ndo_error)(ndo, "invalid hex digit %c in espsecret\n", hex);
236 		return 0;
237 	}
238 }
239 
240 static u_int hex2byte(netdissect_options *ndo, char *hexstring)
241 {
242 	u_int byte;
243 
244 	byte = (hexdigit(ndo, hexstring[0]) << 4) + hexdigit(ndo, hexstring[1]);
245 	return byte;
246 }
247 
248 /*
249  * returns size of binary, 0 on failure.
250  */
251 static
252 int espprint_decode_hex(netdissect_options *ndo,
253 			u_char *binbuf, unsigned int binbuf_len,
254 			char *hex)
255 {
256 	unsigned int len;
257 	int i;
258 
259 	len = strlen(hex) / 2;
260 
261 	if (len > binbuf_len) {
262 		(*ndo->ndo_warning)(ndo, "secret is too big: %d\n", len);
263 		return 0;
264 	}
265 
266 	i = 0;
267 	while (hex[0] != '\0' && hex[1]!='\0') {
268 		binbuf[i] = hex2byte(ndo, hex);
269 		hex += 2;
270 		i++;
271 	}
272 
273 	return i;
274 }
275 
276 /*
277  * decode the form:    SPINUM@IP <tab> ALGONAME:0xsecret
278  */
279 
280 USES_APPLE_DEPRECATED_API
281 static int
282 espprint_decode_encalgo(netdissect_options *ndo,
283 			char *decode, struct sa_list *sa)
284 {
285 	size_t i;
286 	const EVP_CIPHER *evp;
287 	int authlen = 0;
288 	char *colon, *p;
289 
290 	colon = strchr(decode, ':');
291 	if (colon == NULL) {
292 		(*ndo->ndo_warning)(ndo, "failed to decode espsecret: %s\n", decode);
293 		return 0;
294 	}
295 	*colon = '\0';
296 
297 	if (strlen(decode) > strlen("-hmac96") &&
298 	    !strcmp(decode + strlen(decode) - strlen("-hmac96"),
299 		    "-hmac96")) {
300 		p = strstr(decode, "-hmac96");
301 		*p = '\0';
302 		authlen = 12;
303 	}
304 	if (strlen(decode) > strlen("-cbc") &&
305 	    !strcmp(decode + strlen(decode) - strlen("-cbc"), "-cbc")) {
306 		p = strstr(decode, "-cbc");
307 		*p = '\0';
308 	}
309 	evp = EVP_get_cipherbyname(decode);
310 
311 	if (!evp) {
312 		(*ndo->ndo_warning)(ndo, "failed to find cipher algo %s\n", decode);
313 		sa->evp = NULL;
314 		sa->authlen = 0;
315 		sa->ivlen = 0;
316 		return 0;
317 	}
318 
319 	sa->evp = evp;
320 	sa->authlen = authlen;
321 	sa->ivlen = EVP_CIPHER_iv_length(evp);
322 
323 	colon++;
324 	if (colon[0] == '0' && colon[1] == 'x') {
325 		/* decode some hex! */
326 
327 		colon += 2;
328 		sa->secretlen = espprint_decode_hex(ndo, sa->secret, sizeof(sa->secret), colon);
329 		if(sa->secretlen == 0) return 0;
330 	} else {
331 		i = strlen(colon);
332 
333 		if (i < sizeof(sa->secret)) {
334 			memcpy(sa->secret, colon, i);
335 			sa->secretlen = i;
336 		} else {
337 			memcpy(sa->secret, colon, sizeof(sa->secret));
338 			sa->secretlen = sizeof(sa->secret);
339 		}
340 	}
341 
342 	return 1;
343 }
344 USES_APPLE_RST
345 
346 /*
347  * for the moment, ignore the auth algorith, just hard code the authenticator
348  * length. Need to research how openssl looks up HMAC stuff.
349  */
350 static int
351 espprint_decode_authalgo(netdissect_options *ndo,
352 			 char *decode, struct sa_list *sa)
353 {
354 	char *colon;
355 
356 	colon = strchr(decode, ':');
357 	if (colon == NULL) {
358 		(*ndo->ndo_warning)(ndo, "failed to decode espsecret: %s\n", decode);
359 		return 0;
360 	}
361 	*colon = '\0';
362 
363 	if(ascii_strcasecmp(colon,"sha1") == 0 ||
364 	   ascii_strcasecmp(colon,"md5") == 0) {
365 		sa->authlen = 12;
366 	}
367 	return 1;
368 }
369 
370 static void esp_print_decode_ikeline(netdissect_options *ndo, char *line,
371 				     const char *file, int lineno)
372 {
373 	/* it's an IKEv2 secret, store it instead */
374 	struct sa_list sa1;
375 
376 	char *init;
377 	char *icookie, *rcookie;
378 	int   ilen, rlen;
379 	char *authkey;
380 	char *enckey;
381 
382 	init = strsep(&line, " \t");
383 	icookie = strsep(&line, " \t");
384 	rcookie = strsep(&line, " \t");
385 	authkey = strsep(&line, " \t");
386 	enckey  = strsep(&line, " \t");
387 
388 	/* if any fields are missing */
389 	if(!init || !icookie || !rcookie || !authkey || !enckey) {
390 		(*ndo->ndo_warning)(ndo, "print_esp: failed to find all fields for ikev2 at %s:%u",
391 				    file, lineno);
392 
393 		return;
394 	}
395 
396 	ilen = strlen(icookie);
397 	rlen = strlen(rcookie);
398 
399 	if((init[0]!='I' && init[0]!='R')
400 	   || icookie[0]!='0' || icookie[1]!='x'
401 	   || rcookie[0]!='0' || rcookie[1]!='x'
402 	   || ilen!=18
403 	   || rlen!=18) {
404 		(*ndo->ndo_warning)(ndo, "print_esp: line %s:%u improperly formatted.",
405 				    file, lineno);
406 
407 		(*ndo->ndo_warning)(ndo, "init=%s icookie=%s(%u) rcookie=%s(%u)",
408 				    init, icookie, ilen, rcookie, rlen);
409 
410 		return;
411 	}
412 
413 	sa1.spi = 0;
414 	sa1.initiator = (init[0] == 'I');
415 	if(espprint_decode_hex(ndo, sa1.spii, sizeof(sa1.spii), icookie+2)!=8)
416 		return;
417 
418 	if(espprint_decode_hex(ndo, sa1.spir, sizeof(sa1.spir), rcookie+2)!=8)
419 		return;
420 
421 	if(!espprint_decode_encalgo(ndo, enckey, &sa1)) return;
422 
423 	if(!espprint_decode_authalgo(ndo, authkey, &sa1)) return;
424 
425 	esp_print_addsa(ndo, &sa1, FALSE);
426 }
427 
428 /*
429  *
430  * special form: file /name
431  * causes us to go read from this file instead.
432  *
433  */
434 static void esp_print_decode_onesecret(netdissect_options *ndo, char *line,
435 				       const char *file, int lineno)
436 {
437 	struct sa_list sa1;
438 	int sa_def;
439 
440 	char *spikey;
441 	char *decode;
442 
443 	spikey = strsep(&line, " \t");
444 	sa_def = 0;
445 	memset(&sa1, 0, sizeof(struct sa_list));
446 
447 	/* if there is only one token, then it is an algo:key token */
448 	if (line == NULL) {
449 		decode = spikey;
450 		spikey = NULL;
451 		/* sa1.daddr.version = 0; */
452 		/* memset(&sa1.daddr, 0, sizeof(sa1.daddr)); */
453 		/* sa1.spi = 0; */
454 		sa_def    = 1;
455 	} else
456 		decode = line;
457 
458 	if (spikey && ascii_strcasecmp(spikey, "file") == 0) {
459 		/* open file and read it */
460 		FILE *secretfile;
461 		char  fileline[1024];
462 		int   subfile_lineno=0;
463 		char  *nl;
464 		char *filename = line;
465 
466 		secretfile = fopen(filename, FOPEN_READ_TXT);
467 		if (secretfile == NULL) {
468 			(*ndo->ndo_error)(ndo, "print_esp: can't open %s: %s\n",
469 			    filename, strerror(errno));
470 			return;
471 		}
472 
473 		while (fgets(fileline, sizeof(fileline)-1, secretfile) != NULL) {
474 			subfile_lineno++;
475 			/* remove newline from the line */
476 			nl = strchr(fileline, '\n');
477 			if (nl)
478 				*nl = '\0';
479 			if (fileline[0] == '#') continue;
480 			if (fileline[0] == '\0') continue;
481 
482 			esp_print_decode_onesecret(ndo, fileline, filename, subfile_lineno);
483 		}
484 		fclose(secretfile);
485 
486 		return;
487 	}
488 
489 	if (spikey && ascii_strcasecmp(spikey, "ikev2") == 0) {
490 		esp_print_decode_ikeline(ndo, line, file, lineno);
491 		return;
492 	}
493 
494 	if (spikey) {
495 
496 		char *spistr, *foo;
497 		uint32_t spino;
498 
499 		spistr = strsep(&spikey, "@");
500 
501 		spino = strtoul(spistr, &foo, 0);
502 		if (spistr == foo || !spikey) {
503 			(*ndo->ndo_warning)(ndo, "print_esp: failed to decode spi# %s\n", foo);
504 			return;
505 		}
506 
507 		sa1.spi = spino;
508 
509 		if (strtoaddr6(spikey, &sa1.daddr.in6) == 1) {
510 			sa1.daddr_version = 6;
511 		} else if (strtoaddr(spikey, &sa1.daddr.in4) == 1) {
512 			sa1.daddr_version = 4;
513 		} else {
514 			(*ndo->ndo_warning)(ndo, "print_esp: can not decode IP# %s\n", spikey);
515 			return;
516 		}
517 	}
518 
519 	if (decode) {
520 		/* skip any blank spaces */
521 		while (isspace((unsigned char)*decode))
522 			decode++;
523 
524 		if(!espprint_decode_encalgo(ndo, decode, &sa1)) {
525 			return;
526 		}
527 	}
528 
529 	esp_print_addsa(ndo, &sa1, sa_def);
530 }
531 
532 USES_APPLE_DEPRECATED_API
533 static void esp_init(netdissect_options *ndo _U_)
534 {
535 	/*
536 	 * 0.9.6 doesn't appear to define OPENSSL_API_COMPAT, so
537 	 * we check whether it's undefined or it's less than the
538 	 * value for 1.1.0.
539 	 */
540 #if !defined(OPENSSL_API_COMPAT) || OPENSSL_API_COMPAT < 0x10100000L
541 	OpenSSL_add_all_algorithms();
542 #endif
543 	EVP_add_cipher_alias(SN_des_ede3_cbc, "3des");
544 }
545 USES_APPLE_RST
546 
547 void esp_print_decodesecret(netdissect_options *ndo)
548 {
549 	char *line;
550 	char *p;
551 	static int initialized = 0;
552 
553 	if (!initialized) {
554 		esp_init(ndo);
555 		initialized = 1;
556 	}
557 
558 	p = ndo->ndo_espsecret;
559 
560 	while (p && p[0] != '\0') {
561 		/* pick out the first line or first thing until a comma */
562 		if ((line = strsep(&p, "\n,")) == NULL) {
563 			line = p;
564 			p = NULL;
565 		}
566 
567 		esp_print_decode_onesecret(ndo, line, "cmdline", 0);
568 	}
569 
570 	ndo->ndo_espsecret = NULL;
571 }
572 
573 #endif
574 
575 #ifdef HAVE_LIBCRYPTO
576 USES_APPLE_DEPRECATED_API
577 #endif
578 int
579 esp_print(netdissect_options *ndo,
580 	  const u_char *bp, const int length, const u_char *bp2
581 #ifndef HAVE_LIBCRYPTO
582 	_U_
583 #endif
584 	,
585 	int *nhdr
586 #ifndef HAVE_LIBCRYPTO
587 	_U_
588 #endif
589 	,
590 	int *padlen
591 #ifndef HAVE_LIBCRYPTO
592 	_U_
593 #endif
594 	)
595 {
596 	register const struct newesp *esp;
597 	register const u_char *ep;
598 #ifdef HAVE_LIBCRYPTO
599 	const struct ip *ip;
600 	struct sa_list *sa = NULL;
601 	const struct ip6_hdr *ip6 = NULL;
602 	int advance;
603 	int len;
604 	u_char *secret;
605 	int ivlen = 0;
606 	const u_char *ivoff;
607 	const u_char *p;
608 	EVP_CIPHER_CTX *ctx;
609 #endif
610 
611 	esp = (const struct newesp *)bp;
612 
613 #ifdef HAVE_LIBCRYPTO
614 	secret = NULL;
615 	advance = 0;
616 #endif
617 
618 #if 0
619 	/* keep secret out of a register */
620 	p = (u_char *)&secret;
621 #endif
622 
623 	/* 'ep' points to the end of available data. */
624 	ep = ndo->ndo_snapend;
625 
626 	if ((const u_char *)(esp + 1) >= ep) {
627 		ND_PRINT((ndo, "[|ESP]"));
628 		goto fail;
629 	}
630 	ND_PRINT((ndo, "ESP(spi=0x%08x", EXTRACT_32BITS(&esp->esp_spi)));
631 	ND_PRINT((ndo, ",seq=0x%x)", EXTRACT_32BITS(&esp->esp_seq)));
632 	ND_PRINT((ndo, ", length %u", length));
633 
634 #ifndef HAVE_LIBCRYPTO
635 	goto fail;
636 #else
637 	/* initiailize SAs */
638 	if (ndo->ndo_sa_list_head == NULL) {
639 		if (!ndo->ndo_espsecret)
640 			goto fail;
641 
642 		esp_print_decodesecret(ndo);
643 	}
644 
645 	if (ndo->ndo_sa_list_head == NULL)
646 		goto fail;
647 
648 	ip = (const struct ip *)bp2;
649 	switch (IP_V(ip)) {
650 	case 6:
651 		ip6 = (const struct ip6_hdr *)bp2;
652 		/* we do not attempt to decrypt jumbograms */
653 		if (!EXTRACT_16BITS(&ip6->ip6_plen))
654 			goto fail;
655 		/* if we can't get nexthdr, we do not need to decrypt it */
656 		len = sizeof(struct ip6_hdr) + EXTRACT_16BITS(&ip6->ip6_plen);
657 
658 		/* see if we can find the SA, and if so, decode it */
659 		for (sa = ndo->ndo_sa_list_head; sa != NULL; sa = sa->next) {
660 			if (sa->spi == EXTRACT_32BITS(&esp->esp_spi) &&
661 			    sa->daddr_version == 6 &&
662 			    UNALIGNED_MEMCMP(&sa->daddr.in6, &ip6->ip6_dst,
663 				   sizeof(struct in6_addr)) == 0) {
664 				break;
665 			}
666 		}
667 		break;
668 	case 4:
669 		/* nexthdr & padding are in the last fragment */
670 		if (EXTRACT_16BITS(&ip->ip_off) & IP_MF)
671 			goto fail;
672 		len = EXTRACT_16BITS(&ip->ip_len);
673 
674 		/* see if we can find the SA, and if so, decode it */
675 		for (sa = ndo->ndo_sa_list_head; sa != NULL; sa = sa->next) {
676 			if (sa->spi == EXTRACT_32BITS(&esp->esp_spi) &&
677 			    sa->daddr_version == 4 &&
678 			    UNALIGNED_MEMCMP(&sa->daddr.in4, &ip->ip_dst,
679 				   sizeof(struct in_addr)) == 0) {
680 				break;
681 			}
682 		}
683 		break;
684 	default:
685 		goto fail;
686 	}
687 
688 	/* if we didn't find the specific one, then look for
689 	 * an unspecified one.
690 	 */
691 	if (sa == NULL)
692 		sa = ndo->ndo_sa_default;
693 
694 	/* if not found fail */
695 	if (sa == NULL)
696 		goto fail;
697 
698 	/* if we can't get nexthdr, we do not need to decrypt it */
699 	if (ep - bp2 < len)
700 		goto fail;
701 	if (ep - bp2 > len) {
702 		/* FCS included at end of frame (NetBSD 1.6 or later) */
703 		ep = bp2 + len;
704 	}
705 
706 	ivoff = (const u_char *)(esp + 1) + 0;
707 	ivlen = sa->ivlen;
708 	secret = sa->secret;
709 	ep = ep - sa->authlen;
710 
711 	if (sa->evp) {
712 		ctx = EVP_CIPHER_CTX_new();
713 		if (ctx != NULL) {
714 			if (EVP_CipherInit(ctx, sa->evp, secret, NULL, 0) < 0)
715 				(*ndo->ndo_warning)(ndo, "espkey init failed");
716 
717 			p = ivoff;
718 			EVP_CipherInit(ctx, NULL, NULL, p, 0);
719 			EVP_Cipher(ctx, __DECONST(u_char *, p + ivlen),
720 			    p + ivlen, ep - (p + ivlen));
721 			EVP_CIPHER_CTX_free(ctx);
722 			advance = ivoff - (const u_char *)esp + ivlen;
723 		} else
724 			advance = sizeof(struct newesp);
725 	} else
726 		advance = sizeof(struct newesp);
727 
728 	/* sanity check for pad length */
729 	if (ep - bp < *(ep - 2))
730 		goto fail;
731 
732 	if (padlen)
733 		*padlen = *(ep - 2) + 2;
734 
735 	if (nhdr)
736 		*nhdr = *(ep - 1);
737 
738 	ND_PRINT((ndo, ": "));
739 	return advance;
740 #endif
741 
742 fail:
743 	return -1;
744 }
745 #ifdef HAVE_LIBCRYPTO
746 USES_APPLE_RST
747 #endif
748 
749 /*
750  * Local Variables:
751  * c-style: whitesmith
752  * c-basic-offset: 8
753  * End:
754  */
755