xref: /openbsd/lib/libcrypto/x509/x509_ncons.c (revision 8b5faa71)
1 /* $OpenBSD: x509_ncons.c,v 1.11 2024/07/13 15:08:58 tb Exp $ */
2 /* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
3  * project.
4  */
5 /* ====================================================================
6  * Copyright (c) 2003 The OpenSSL Project.  All rights reserved.
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
17  *    the documentation and/or other materials provided with the
18  *    distribution.
19  *
20  * 3. All advertising materials mentioning features or use of this
21  *    software must display the following acknowledgment:
22  *    "This product includes software developed by the OpenSSL Project
23  *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
24  *
25  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
26  *    endorse or promote products derived from this software without
27  *    prior written permission. For written permission, please contact
28  *    licensing@OpenSSL.org.
29  *
30  * 5. Products derived from this software may not be called "OpenSSL"
31  *    nor may "OpenSSL" appear in their names without prior written
32  *    permission of the OpenSSL Project.
33  *
34  * 6. Redistributions of any form whatsoever must retain the following
35  *    acknowledgment:
36  *    "This product includes software developed by the OpenSSL Project
37  *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
38  *
39  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
40  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
41  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
42  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
43  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
44  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
45  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
46  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
48  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
49  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
50  * OF THE POSSIBILITY OF SUCH DAMAGE.
51  * ====================================================================
52  *
53  * This product includes cryptographic software written by Eric Young
54  * (eay@cryptsoft.com).  This product includes software written by Tim
55  * Hudson (tjh@cryptsoft.com).
56  *
57  */
58 
59 #include <stdio.h>
60 #include <string.h>
61 
62 #include <openssl/asn1t.h>
63 #include <openssl/conf.h>
64 #include <openssl/err.h>
65 #include <openssl/x509v3.h>
66 
67 #include "x509_local.h"
68 
69 static void *v2i_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method,
70     X509V3_CTX *ctx, STACK_OF(CONF_VALUE) *nval);
71 static int i2r_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method,
72     void *a, BIO *bp, int ind);
73 static int do_i2r_name_constraints(const X509V3_EXT_METHOD *method,
74     STACK_OF(GENERAL_SUBTREE) *trees, BIO *bp, int ind, char *name);
75 static int print_nc_ipadd(BIO *bp, ASN1_OCTET_STRING *ip);
76 
77 static int nc_match(GENERAL_NAME *gen, NAME_CONSTRAINTS *nc);
78 static int nc_match_single(GENERAL_NAME *sub, GENERAL_NAME *gen);
79 static int nc_dn(X509_NAME *sub, X509_NAME *nm);
80 static int nc_dns(ASN1_IA5STRING *sub, ASN1_IA5STRING *dns);
81 static int nc_email(ASN1_IA5STRING *sub, ASN1_IA5STRING *eml);
82 static int nc_uri(ASN1_IA5STRING *uri, ASN1_IA5STRING *base);
83 
84 static const X509V3_EXT_METHOD x509v3_ext_name_constraints = {
85 	.ext_nid = NID_name_constraints,
86 	.ext_flags = 0,
87 	.it = &NAME_CONSTRAINTS_it,
88 	.ext_new = NULL,
89 	.ext_free = NULL,
90 	.d2i = NULL,
91 	.i2d = NULL,
92 	.i2s = NULL,
93 	.s2i = NULL,
94 	.i2v = NULL,
95 	.v2i = v2i_NAME_CONSTRAINTS,
96 	.i2r = i2r_NAME_CONSTRAINTS,
97 	.r2i = NULL,
98 	.usr_data = NULL,
99 };
100 
101 const X509V3_EXT_METHOD *
x509v3_ext_method_name_constraints(void)102 x509v3_ext_method_name_constraints(void)
103 {
104 	return &x509v3_ext_name_constraints;
105 }
106 
107 static const ASN1_TEMPLATE GENERAL_SUBTREE_seq_tt[] = {
108 	{
109 		.flags = 0,
110 		.tag = 0,
111 		.offset = offsetof(GENERAL_SUBTREE, base),
112 		.field_name = "base",
113 		.item = &GENERAL_NAME_it,
114 	},
115 	{
116 		.flags = ASN1_TFLG_IMPLICIT | ASN1_TFLG_OPTIONAL,
117 		.tag = 0,
118 		.offset = offsetof(GENERAL_SUBTREE, minimum),
119 		.field_name = "minimum",
120 		.item = &ASN1_INTEGER_it,
121 	},
122 	{
123 		.flags = ASN1_TFLG_IMPLICIT | ASN1_TFLG_OPTIONAL,
124 		.tag = 1,
125 		.offset = offsetof(GENERAL_SUBTREE, maximum),
126 		.field_name = "maximum",
127 		.item = &ASN1_INTEGER_it,
128 	},
129 };
130 
131 const ASN1_ITEM GENERAL_SUBTREE_it = {
132 	.itype = ASN1_ITYPE_SEQUENCE,
133 	.utype = V_ASN1_SEQUENCE,
134 	.templates = GENERAL_SUBTREE_seq_tt,
135 	.tcount = sizeof(GENERAL_SUBTREE_seq_tt) / sizeof(ASN1_TEMPLATE),
136 	.funcs = NULL,
137 	.size = sizeof(GENERAL_SUBTREE),
138 	.sname = "GENERAL_SUBTREE",
139 };
140 LCRYPTO_ALIAS(GENERAL_SUBTREE_it);
141 
142 static const ASN1_TEMPLATE NAME_CONSTRAINTS_seq_tt[] = {
143 	{
144 		.flags = ASN1_TFLG_IMPLICIT | ASN1_TFLG_SEQUENCE_OF | ASN1_TFLG_OPTIONAL,
145 		.tag = 0,
146 		.offset = offsetof(NAME_CONSTRAINTS, permittedSubtrees),
147 		.field_name = "permittedSubtrees",
148 		.item = &GENERAL_SUBTREE_it,
149 	},
150 	{
151 		.flags = ASN1_TFLG_IMPLICIT | ASN1_TFLG_SEQUENCE_OF | ASN1_TFLG_OPTIONAL,
152 		.tag = 1,
153 		.offset = offsetof(NAME_CONSTRAINTS, excludedSubtrees),
154 		.field_name = "excludedSubtrees",
155 		.item = &GENERAL_SUBTREE_it,
156 	},
157 };
158 
159 const ASN1_ITEM NAME_CONSTRAINTS_it = {
160 	.itype = ASN1_ITYPE_SEQUENCE,
161 	.utype = V_ASN1_SEQUENCE,
162 	.templates = NAME_CONSTRAINTS_seq_tt,
163 	.tcount = sizeof(NAME_CONSTRAINTS_seq_tt) / sizeof(ASN1_TEMPLATE),
164 	.funcs = NULL,
165 	.size = sizeof(NAME_CONSTRAINTS),
166 	.sname = "NAME_CONSTRAINTS",
167 };
168 LCRYPTO_ALIAS(NAME_CONSTRAINTS_it);
169 
170 
171 GENERAL_SUBTREE *
GENERAL_SUBTREE_new(void)172 GENERAL_SUBTREE_new(void)
173 {
174 	return (GENERAL_SUBTREE*)ASN1_item_new(&GENERAL_SUBTREE_it);
175 }
176 LCRYPTO_ALIAS(GENERAL_SUBTREE_new);
177 
178 void
GENERAL_SUBTREE_free(GENERAL_SUBTREE * a)179 GENERAL_SUBTREE_free(GENERAL_SUBTREE *a)
180 {
181 	ASN1_item_free((ASN1_VALUE *)a, &GENERAL_SUBTREE_it);
182 }
183 LCRYPTO_ALIAS(GENERAL_SUBTREE_free);
184 
185 NAME_CONSTRAINTS *
NAME_CONSTRAINTS_new(void)186 NAME_CONSTRAINTS_new(void)
187 {
188 	return (NAME_CONSTRAINTS*)ASN1_item_new(&NAME_CONSTRAINTS_it);
189 }
190 LCRYPTO_ALIAS(NAME_CONSTRAINTS_new);
191 
192 void
NAME_CONSTRAINTS_free(NAME_CONSTRAINTS * a)193 NAME_CONSTRAINTS_free(NAME_CONSTRAINTS *a)
194 {
195 	ASN1_item_free((ASN1_VALUE *)a, &NAME_CONSTRAINTS_it);
196 }
197 LCRYPTO_ALIAS(NAME_CONSTRAINTS_free);
198 
199 static void *
v2i_NAME_CONSTRAINTS(const X509V3_EXT_METHOD * method,X509V3_CTX * ctx,STACK_OF (CONF_VALUE)* nval)200 v2i_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method, X509V3_CTX *ctx,
201     STACK_OF(CONF_VALUE) *nval)
202 {
203 	int i;
204 	CONF_VALUE tval, *val;
205 	STACK_OF(GENERAL_SUBTREE) **ptree = NULL;
206 	NAME_CONSTRAINTS *ncons = NULL;
207 	GENERAL_SUBTREE *sub = NULL;
208 
209 	ncons = NAME_CONSTRAINTS_new();
210 	if (!ncons)
211 		goto memerr;
212 	for (i = 0; i < sk_CONF_VALUE_num(nval); i++) {
213 		val = sk_CONF_VALUE_value(nval, i);
214 		if (!strncmp(val->name, "permitted", 9) && val->name[9]) {
215 			ptree = &ncons->permittedSubtrees;
216 			tval.name = val->name + 10;
217 		} else if (!strncmp(val->name, "excluded", 8) && val->name[8]) {
218 			ptree = &ncons->excludedSubtrees;
219 			tval.name = val->name + 9;
220 		} else {
221 			X509V3error(X509V3_R_INVALID_SYNTAX);
222 			goto err;
223 		}
224 		tval.value = val->value;
225 		sub = GENERAL_SUBTREE_new();
226 		if (!v2i_GENERAL_NAME_ex(sub->base, method, ctx, &tval, 1))
227 			goto err;
228 		if (!*ptree)
229 			*ptree = sk_GENERAL_SUBTREE_new_null();
230 		if (!*ptree || !sk_GENERAL_SUBTREE_push(*ptree, sub))
231 			goto memerr;
232 		sub = NULL;
233 	}
234 
235 	return ncons;
236 
237 memerr:
238 	X509V3error(ERR_R_MALLOC_FAILURE);
239 err:
240 	NAME_CONSTRAINTS_free(ncons);
241 	GENERAL_SUBTREE_free(sub);
242 	return NULL;
243 }
244 
245 static int
i2r_NAME_CONSTRAINTS(const X509V3_EXT_METHOD * method,void * a,BIO * bp,int ind)246 i2r_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method, void *a, BIO *bp, int ind)
247 {
248 	NAME_CONSTRAINTS *ncons = a;
249 
250 	do_i2r_name_constraints(method, ncons->permittedSubtrees,
251 	    bp, ind, "Permitted");
252 	do_i2r_name_constraints(method, ncons->excludedSubtrees,
253 	    bp, ind, "Excluded");
254 	return 1;
255 }
256 
257 static int
do_i2r_name_constraints(const X509V3_EXT_METHOD * method,STACK_OF (GENERAL_SUBTREE)* trees,BIO * bp,int ind,char * name)258 do_i2r_name_constraints(const X509V3_EXT_METHOD *method,
259     STACK_OF(GENERAL_SUBTREE) *trees, BIO *bp, int ind, char *name)
260 {
261 	GENERAL_SUBTREE *tree;
262 	int i;
263 
264 	if (sk_GENERAL_SUBTREE_num(trees) > 0)
265 		BIO_printf(bp, "%*s%s:\n", ind, "", name);
266 	for (i = 0; i < sk_GENERAL_SUBTREE_num(trees); i++) {
267 		tree = sk_GENERAL_SUBTREE_value(trees, i);
268 		BIO_printf(bp, "%*s", ind + 2, "");
269 		if (tree->base->type == GEN_IPADD)
270 			print_nc_ipadd(bp, tree->base->d.ip);
271 		else
272 			GENERAL_NAME_print(bp, tree->base);
273 		BIO_puts(bp, "\n");
274 	}
275 	return 1;
276 }
277 
278 static int
print_nc_ipadd(BIO * bp,ASN1_OCTET_STRING * ip)279 print_nc_ipadd(BIO *bp, ASN1_OCTET_STRING *ip)
280 {
281 	int i, len;
282 	unsigned char *p;
283 
284 	p = ip->data;
285 	len = ip->length;
286 	BIO_puts(bp, "IP:");
287 	if (len == 8) {
288 		BIO_printf(bp, "%d.%d.%d.%d/%d.%d.%d.%d",
289 		    p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7]);
290 	} else if (len == 32) {
291 		for (i = 0; i < 16; i++) {
292 			BIO_printf(bp, "%X", p[0] << 8 | p[1]);
293 			p += 2;
294 			if (i == 7)
295 				BIO_puts(bp, "/");
296 			else if (i != 15)
297 				BIO_puts(bp, ":");
298 		}
299 	} else
300 		BIO_printf(bp, "IP Address:<invalid>");
301 	return 1;
302 }
303 
304 /* Check a certificate conforms to a specified set of constraints.
305  * Return values:
306  *  X509_V_OK: All constraints obeyed.
307  *  X509_V_ERR_PERMITTED_VIOLATION: Permitted subtree violation.
308  *  X509_V_ERR_EXCLUDED_VIOLATION: Excluded subtree violation.
309  *  X509_V_ERR_SUBTREE_MINMAX: Min or max values present and matching type.
310  *  X509_V_ERR_UNSUPPORTED_CONSTRAINT_TYPE:  Unsupported constraint type.
311  *  X509_V_ERR_UNSUPPORTED_CONSTRAINT_SYNTAX: bad unsupported constraint syntax.
312  *  X509_V_ERR_UNSUPPORTED_NAME_SYNTAX: bad or unsupported syntax of name
313  */
314 
315 int
NAME_CONSTRAINTS_check(X509 * x,NAME_CONSTRAINTS * nc)316 NAME_CONSTRAINTS_check(X509 *x, NAME_CONSTRAINTS *nc)
317 {
318 	int r, i;
319 	X509_NAME *nm;
320 
321 	nm = X509_get_subject_name(x);
322 
323 	if (X509_NAME_entry_count(nm) > 0) {
324 		GENERAL_NAME gntmp;
325 		gntmp.type = GEN_DIRNAME;
326 		gntmp.d.directoryName = nm;
327 
328 		r = nc_match(&gntmp, nc);
329 
330 		if (r != X509_V_OK)
331 			return r;
332 
333 		gntmp.type = GEN_EMAIL;
334 
335 		/* Process any email address attributes in subject name */
336 
337 		for (i = -1;;) {
338 			X509_NAME_ENTRY *ne;
339 			i = X509_NAME_get_index_by_NID(nm,
340 			    NID_pkcs9_emailAddress, i);
341 			if (i == -1)
342 				break;
343 			ne = X509_NAME_get_entry(nm, i);
344 			gntmp.d.rfc822Name = X509_NAME_ENTRY_get_data(ne);
345 			if (gntmp.d.rfc822Name->type != V_ASN1_IA5STRING)
346 				return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
347 
348 			r = nc_match(&gntmp, nc);
349 
350 			if (r != X509_V_OK)
351 				return r;
352 		}
353 
354 	}
355 
356 	for (i = 0; i < sk_GENERAL_NAME_num(x->altname); i++) {
357 		GENERAL_NAME *gen = sk_GENERAL_NAME_value(x->altname, i);
358 		r = nc_match(gen, nc);
359 		if (r != X509_V_OK)
360 			return r;
361 	}
362 	return X509_V_OK;
363 }
364 LCRYPTO_ALIAS(NAME_CONSTRAINTS_check);
365 static int
nc_match(GENERAL_NAME * gen,NAME_CONSTRAINTS * nc)366 nc_match(GENERAL_NAME *gen, NAME_CONSTRAINTS *nc)
367 {
368 	GENERAL_SUBTREE *sub;
369 	int i, r, match = 0;
370 
371 	/* Permitted subtrees: if any subtrees exist of matching the type
372 	 * at least one subtree must match.
373 	 */
374 
375 	for (i = 0; i < sk_GENERAL_SUBTREE_num(nc->permittedSubtrees); i++) {
376 		sub = sk_GENERAL_SUBTREE_value(nc->permittedSubtrees, i);
377 		if (gen->type != sub->base->type)
378 			continue;
379 		if (sub->minimum || sub->maximum)
380 			return X509_V_ERR_SUBTREE_MINMAX;
381 		/* If we already have a match don't bother trying any more */
382 		if (match == 2)
383 			continue;
384 		if (match == 0)
385 			match = 1;
386 		r = nc_match_single(gen, sub->base);
387 		if (r == X509_V_OK)
388 			match = 2;
389 		else if (r != X509_V_ERR_PERMITTED_VIOLATION)
390 			return r;
391 	}
392 
393 	if (match == 1)
394 		return X509_V_ERR_PERMITTED_VIOLATION;
395 
396 	/* Excluded subtrees: must not match any of these */
397 
398 	for (i = 0; i < sk_GENERAL_SUBTREE_num(nc->excludedSubtrees); i++) {
399 		sub = sk_GENERAL_SUBTREE_value(nc->excludedSubtrees, i);
400 		if (gen->type != sub->base->type)
401 			continue;
402 		if (sub->minimum || sub->maximum)
403 			return X509_V_ERR_SUBTREE_MINMAX;
404 
405 		r = nc_match_single(gen, sub->base);
406 		if (r == X509_V_OK)
407 			return X509_V_ERR_EXCLUDED_VIOLATION;
408 		else if (r != X509_V_ERR_PERMITTED_VIOLATION)
409 			return r;
410 
411 	}
412 
413 	return X509_V_OK;
414 }
415 
416 static int
nc_match_single(GENERAL_NAME * gen,GENERAL_NAME * base)417 nc_match_single(GENERAL_NAME *gen, GENERAL_NAME *base)
418 {
419 	switch (base->type) {
420 	case GEN_DIRNAME:
421 		return nc_dn(gen->d.directoryName, base->d.directoryName);
422 
423 	case GEN_DNS:
424 		return nc_dns(gen->d.dNSName, base->d.dNSName);
425 
426 	case GEN_EMAIL:
427 		return nc_email(gen->d.rfc822Name, base->d.rfc822Name);
428 
429 	case GEN_URI:
430 		return nc_uri(gen->d.uniformResourceIdentifier,
431 		    base->d.uniformResourceIdentifier);
432 
433 	default:
434 		return X509_V_ERR_UNSUPPORTED_CONSTRAINT_TYPE;
435 	}
436 }
437 
438 /* directoryName name constraint matching.
439  * The canonical encoding of X509_NAME makes this comparison easy. It is
440  * matched if the subtree is a subset of the name.
441  */
442 
443 static int
nc_dn(X509_NAME * nm,X509_NAME * base)444 nc_dn(X509_NAME *nm, X509_NAME *base)
445 {
446 	/* Ensure canonical encodings are up to date.  */
447 	if (nm->modified && i2d_X509_NAME(nm, NULL) < 0)
448 		return X509_V_ERR_OUT_OF_MEM;
449 	if (base->modified && i2d_X509_NAME(base, NULL) < 0)
450 		return X509_V_ERR_OUT_OF_MEM;
451 	if (base->canon_enclen > nm->canon_enclen)
452 		return X509_V_ERR_PERMITTED_VIOLATION;
453 	if (memcmp(base->canon_enc, nm->canon_enc, base->canon_enclen))
454 		return X509_V_ERR_PERMITTED_VIOLATION;
455 	return X509_V_OK;
456 }
457 
458 static int
nc_dns(ASN1_IA5STRING * dns,ASN1_IA5STRING * base)459 nc_dns(ASN1_IA5STRING *dns, ASN1_IA5STRING *base)
460 {
461 	char *baseptr = (char *)base->data;
462 	char *dnsptr = (char *)dns->data;
463 
464 	/* Empty matches everything */
465 	if (!*baseptr)
466 		return X509_V_OK;
467 	/* Otherwise can add zero or more components on the left so
468 	 * compare RHS and if dns is longer and expect '.' as preceding
469 	 * character.
470 	 */
471 	if (dns->length > base->length) {
472 		dnsptr += dns->length - base->length;
473 		if (baseptr[0] != '.' && dnsptr[-1] != '.')
474 			return X509_V_ERR_PERMITTED_VIOLATION;
475 	}
476 
477 	if (strcasecmp(baseptr, dnsptr))
478 		return X509_V_ERR_PERMITTED_VIOLATION;
479 
480 	return X509_V_OK;
481 }
482 
483 static int
nc_email(ASN1_IA5STRING * eml,ASN1_IA5STRING * base)484 nc_email(ASN1_IA5STRING *eml, ASN1_IA5STRING *base)
485 {
486 	const char *baseptr = (char *)base->data;
487 	const char *emlptr = (char *)eml->data;
488 	const char *baseat = strchr(baseptr, '@');
489 	const char *emlat = strchr(emlptr, '@');
490 
491 	if (!emlat)
492 		return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
493 	/* Special case: initial '.' is RHS match */
494 	if (!baseat && (*baseptr == '.')) {
495 		if (eml->length > base->length) {
496 			emlptr += eml->length - base->length;
497 			if (!strcasecmp(baseptr, emlptr))
498 				return X509_V_OK;
499 		}
500 		return X509_V_ERR_PERMITTED_VIOLATION;
501 	}
502 
503 	/* If we have anything before '@' match local part */
504 
505 	if (baseat) {
506 		if (baseat != baseptr) {
507 			if ((baseat - baseptr) != (emlat - emlptr))
508 				return X509_V_ERR_PERMITTED_VIOLATION;
509 			/* Case sensitive match of local part */
510 			if (strncmp(baseptr, emlptr, emlat - emlptr))
511 				return X509_V_ERR_PERMITTED_VIOLATION;
512 		}
513 		/* Position base after '@' */
514 		baseptr = baseat + 1;
515 	}
516 	emlptr = emlat + 1;
517 	/* Just have hostname left to match: case insensitive */
518 	if (strcasecmp(baseptr, emlptr))
519 		return X509_V_ERR_PERMITTED_VIOLATION;
520 
521 	return X509_V_OK;
522 }
523 
524 static int
nc_uri(ASN1_IA5STRING * uri,ASN1_IA5STRING * base)525 nc_uri(ASN1_IA5STRING *uri, ASN1_IA5STRING *base)
526 {
527 	const char *baseptr = (char *)base->data;
528 	const char *hostptr = (char *)uri->data;
529 	const char *p = strchr(hostptr, ':');
530 	int hostlen;
531 
532 	/* Check for foo:// and skip past it */
533 	if (!p || (p[1] != '/') || (p[2] != '/'))
534 		return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
535 	hostptr = p + 3;
536 
537 	/* Determine length of hostname part of URI */
538 
539 	/* Look for a port indicator as end of hostname first */
540 
541 	p = strchr(hostptr, ':');
542 	/* Otherwise look for trailing slash */
543 	if (!p)
544 		p = strchr(hostptr, '/');
545 
546 	if (!p)
547 		hostlen = strlen(hostptr);
548 	else
549 		hostlen = p - hostptr;
550 
551 	if (hostlen == 0)
552 		return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
553 
554 	/* Special case: initial '.' is RHS match */
555 	if (*baseptr == '.') {
556 		if (hostlen > base->length) {
557 			p = hostptr + hostlen - base->length;
558 			if (!strncasecmp(p, baseptr, base->length))
559 				return X509_V_OK;
560 		}
561 		return X509_V_ERR_PERMITTED_VIOLATION;
562 	}
563 
564 	if ((base->length != (int)hostlen) ||
565 	    strncasecmp(hostptr, baseptr, hostlen))
566 		return X509_V_ERR_PERMITTED_VIOLATION;
567 
568 	return X509_V_OK;
569 }
570