xref: /openbsd/lib/libcrypto/x509/x509_utl.c (revision d1aeef77)

/* $OpenBSD: x509_utl.c,v 1.19 2024/07/08 06:57:37 jca Exp $ */
/* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
 * project.
 */
/* ====================================================================
 * Copyright (c) 1999-2003 The OpenSSL Project.  All rights reserved.
 *
 * 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. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    licensing@OpenSSL.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED 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 OpenSSL PROJECT OR
 * ITS 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 product includes cryptographic software written by Eric Young
 * (eay@cryptsoft.com).  This product includes software written by Tim
 * Hudson (tjh@cryptsoft.com).
 *
 */

#include <ctype.h>
#include <limits.h>
#include <stdio.h>
#include <string.h>

#include <openssl/asn1.h>
#include <openssl/bn.h>
#include <openssl/conf.h>
#include <openssl/err.h>
#include <openssl/x509v3.h>

#include "bytestring.h"

static char *bn_to_string(const BIGNUM *bn);
static char *strip_spaces(char *name);
static int sk_strcmp(const char * const *a, const char * const *b);
static STACK_OF(OPENSSL_STRING) *get_email(X509_NAME *name,
    GENERAL_NAMES *gens);
static void str_free(OPENSSL_STRING str);
static int append_ia5(STACK_OF(OPENSSL_STRING) **sk, ASN1_IA5STRING *email);

static int ipv4_from_asc(unsigned char *v4, const char *in);
static int ipv6_from_asc(unsigned char *v6, const char *in);
static int ipv6_cb(const char *elem, int len, void *usr);
static int ipv6_hex(unsigned char *out, const char *in, int inlen);

/* Add a CONF_VALUE name-value pair to stack. */
int
X509V3_add_value(const char *name, const char *value,
    STACK_OF(CONF_VALUE) **extlist)
{
	CONF_VALUE *vtmp = NULL;
	STACK_OF(CONF_VALUE) *free_exts = NULL;

	if ((vtmp = calloc(1, sizeof(CONF_VALUE))) == NULL)
		goto err;
	if (name != NULL) {
		if ((vtmp->name = strdup(name)) == NULL)
			goto err;
	}
	if (value != NULL) {
		if ((vtmp->value = strdup(value)) == NULL)
			goto err;
	}

	if (*extlist == NULL) {
		if ((free_exts = *extlist = sk_CONF_VALUE_new_null()) == NULL)
			goto err;
	}

	if (!sk_CONF_VALUE_push(*extlist, vtmp))
		goto err;

	return 1;

 err:
	X509V3error(ERR_R_MALLOC_FAILURE);
	X509V3_conf_free(vtmp);
	if (free_exts != NULL) {
		sk_CONF_VALUE_free(*extlist);
		*extlist = NULL;
	}
	return 0;
}
LCRYPTO_ALIAS(X509V3_add_value);

int
X509V3_add_value_uchar(const char *name, const unsigned char *value,
    STACK_OF(CONF_VALUE) **extlist)
{
	return X509V3_add_value(name, (const char *)value, extlist);
}
LCRYPTO_ALIAS(X509V3_add_value_uchar);

/* Free function for STACK_OF(CONF_VALUE) */

void
X509V3_conf_free(CONF_VALUE *conf)
{
	if (!conf)
		return;
	free(conf->name);
	free(conf->value);
	free(conf->section);
	free(conf);
}
LCRYPTO_ALIAS(X509V3_conf_free);

int
X509V3_add_value_bool(const char *name, int asn1_bool,
    STACK_OF(CONF_VALUE) **extlist)
{
	if (asn1_bool)
		return X509V3_add_value(name, "TRUE", extlist);
	return X509V3_add_value(name, "FALSE", extlist);
}
LCRYPTO_ALIAS(X509V3_add_value_bool);

int
X509V3_add_value_bool_nf(const char *name, int asn1_bool,
    STACK_OF(CONF_VALUE) **extlist)
{
	if (asn1_bool)
		return X509V3_add_value(name, "TRUE", extlist);
	return 1;
}
LCRYPTO_ALIAS(X509V3_add_value_bool_nf);

static char *
bn_to_string(const BIGNUM *bn)
{
	const char *sign = "";
	char *bnstr, *hex;
	char *ret = NULL;

	/* Only display small numbers in decimal, as conversion is quadratic. */
	if (BN_num_bits(bn) < 128)
		return BN_bn2dec(bn);

	if ((hex = bnstr = BN_bn2hex(bn)) == NULL)
		goto err;

	if (BN_is_negative(bn)) {
		sign = "-";
		hex++;
	}

	if (asprintf(&ret, "%s0x%s", sign, hex) == -1)
		ret = NULL;

 err:
	free(bnstr);
	return ret;
}

char *
i2s_ASN1_ENUMERATED(X509V3_EXT_METHOD *method, const ASN1_ENUMERATED *a)
{
	BIGNUM *bntmp;
	char *strtmp = NULL;

	if (a == NULL)
		return NULL;
	if ((bntmp = ASN1_ENUMERATED_to_BN(a, NULL)) == NULL ||
	    (strtmp = bn_to_string(bntmp)) == NULL)
		X509V3error(ERR_R_MALLOC_FAILURE);
	BN_free(bntmp);
	return strtmp;
}
LCRYPTO_ALIAS(i2s_ASN1_ENUMERATED);

char *
i2s_ASN1_ENUMERATED_TABLE(X509V3_EXT_METHOD *method, const ASN1_ENUMERATED *e)
{
	const BIT_STRING_BITNAME *enam;
	long strval;

	strval = ASN1_ENUMERATED_get(e);
	for (enam = method->usr_data; enam->lname; enam++) {
		if (strval == enam->bitnum)
			return strdup(enam->lname);
	}
	return i2s_ASN1_ENUMERATED(method, e);
}
LCRYPTO_ALIAS(i2s_ASN1_ENUMERATED_TABLE);

char *
i2s_ASN1_INTEGER(X509V3_EXT_METHOD *method, const ASN1_INTEGER *a)
{
	BIGNUM *bntmp;
	char *strtmp = NULL;

	if (a == NULL)
		return NULL;
	if ((bntmp = ASN1_INTEGER_to_BN(a, NULL)) == NULL ||
	    (strtmp = bn_to_string(bntmp)) == NULL)
		X509V3error(ERR_R_MALLOC_FAILURE);
	BN_free(bntmp);
	return strtmp;
}
LCRYPTO_ALIAS(i2s_ASN1_INTEGER);

ASN1_INTEGER *
s2i_ASN1_INTEGER(X509V3_EXT_METHOD *method, const char *value)
{
	BIGNUM *bn = NULL;
	ASN1_INTEGER *aint;
	int isneg = 0, ishex = 0;
	int ret;

	if (!value) {
		X509V3error(X509V3_R_INVALID_NULL_VALUE);
		return NULL;
	}
	if ((bn = BN_new()) == NULL) {
		X509V3error(ERR_R_MALLOC_FAILURE);
		return NULL;
	}
	if (value[0] == '-') {
		value++;
		isneg = 1;
	}

	if (value[0] == '0' && (value[1] == 'x' || value[1] == 'X')) {
		value += 2;
		ishex = 1;
	}

	if (ishex)
		ret = BN_hex2bn(&bn, value);
	else
		ret = BN_dec2bn(&bn, value);

	if (!ret || value[ret]) {
		BN_free(bn);
		X509V3error(X509V3_R_BN_DEC2BN_ERROR);
		return NULL;
	}

	if (BN_is_zero(bn))
		isneg = 0;

	aint = BN_to_ASN1_INTEGER(bn, NULL);
	BN_free(bn);
	if (!aint) {
		X509V3error(X509V3_R_BN_TO_ASN1_INTEGER_ERROR);
		return NULL;
	}
	if (isneg)
		aint->type |= V_ASN1_NEG;
	return aint;
}
LCRYPTO_ALIAS(s2i_ASN1_INTEGER);

int
X509V3_add_value_int(const char *name, const ASN1_INTEGER *aint,
    STACK_OF(CONF_VALUE) **extlist)
{
	char *strtmp;
	int ret;

	if (!aint)
		return 1;
	if (!(strtmp = i2s_ASN1_INTEGER(NULL, aint)))
		return 0;
	ret = X509V3_add_value(name, strtmp, extlist);
	free(strtmp);
	return ret;
}
LCRYPTO_ALIAS(X509V3_add_value_int);

int
X509V3_get_value_bool(const CONF_VALUE *value, int *asn1_bool)
{
	char *btmp;

	if (!(btmp = value->value))
		goto err;
	if (!strcmp(btmp, "TRUE") || !strcmp(btmp, "true") ||
	    !strcmp(btmp, "Y") || !strcmp(btmp, "y") ||
	    !strcmp(btmp, "YES") || !strcmp(btmp, "yes")) {
		*asn1_bool = 0xff;
		return 1;
	} else if (!strcmp(btmp, "FALSE") || !strcmp(btmp, "false") ||
	    !strcmp(btmp, "N") || !strcmp(btmp, "n") ||
	    !strcmp(btmp, "NO") || !strcmp(btmp, "no")) {
		*asn1_bool = 0;
		return 1;
	}

 err:
	X509V3error(X509V3_R_INVALID_BOOLEAN_STRING);
	X509V3_conf_err(value);
	return 0;
}
LCRYPTO_ALIAS(X509V3_get_value_bool);

int
X509V3_get_value_int(const CONF_VALUE *value, ASN1_INTEGER **aint)
{
	ASN1_INTEGER *itmp;

	if (!(itmp = s2i_ASN1_INTEGER(NULL, value->value))) {
		X509V3_conf_err(value);
		return 0;
	}
	*aint = itmp;
	return 1;
}
LCRYPTO_ALIAS(X509V3_get_value_int);

#define HDR_NAME	1
#define HDR_VALUE	2

/*#define DEBUG*/

STACK_OF(CONF_VALUE) *
X509V3_parse_list(const char *line)
{
	char *p, *q, c;
	char *ntmp, *vtmp;
	STACK_OF(CONF_VALUE) *values = NULL;
	char *linebuf;
	int state;

	/* We are going to modify the line so copy it first */
	if ((linebuf = strdup(line)) == NULL) {
		X509V3error(ERR_R_MALLOC_FAILURE);
		goto err;
	}
	state = HDR_NAME;
	ntmp = NULL;

	/* Go through all characters */
	for (p = linebuf, q = linebuf; (c = *p) && (c != '\r') &&
	    (c != '\n'); p++) {

		switch (state) {
		case HDR_NAME:
			if (c == ':') {
				state = HDR_VALUE;
				*p = 0;
				ntmp = strip_spaces(q);
				if (!ntmp) {
					X509V3error(X509V3_R_INVALID_NULL_NAME);
					goto err;
				}
				q = p + 1;
			} else if (c == ',') {
				*p = 0;
				ntmp = strip_spaces(q);
				q = p + 1;
				if (!ntmp) {
					X509V3error(X509V3_R_INVALID_NULL_NAME);
					goto err;
				}
				X509V3_add_value(ntmp, NULL, &values);
			}
			break;

		case HDR_VALUE:
			if (c == ',') {
				state = HDR_NAME;
				*p = 0;
				vtmp = strip_spaces(q);
				if (!vtmp) {
					X509V3error(X509V3_R_INVALID_NULL_VALUE);
					goto err;
				}
				X509V3_add_value(ntmp, vtmp, &values);
				ntmp = NULL;
				q = p + 1;
			}

		}
	}

	if (state == HDR_VALUE) {
		vtmp = strip_spaces(q);
		if (!vtmp) {
			X509V3error(X509V3_R_INVALID_NULL_VALUE);
			goto err;
		}
		X509V3_add_value(ntmp, vtmp, &values);
	} else {
		ntmp = strip_spaces(q);
		if (!ntmp) {
			X509V3error(X509V3_R_INVALID_NULL_NAME);
			goto err;
		}
		X509V3_add_value(ntmp, NULL, &values);
	}
	free(linebuf);
	return values;

 err:
	free(linebuf);
	sk_CONF_VALUE_pop_free(values, X509V3_conf_free);
	return NULL;

}
LCRYPTO_ALIAS(X509V3_parse_list);

/* Delete leading and trailing spaces from a string */
static char *
strip_spaces(char *name)
{
	char *p, *q;

	/* Skip over leading spaces */
	p = name;
	while (*p && isspace((unsigned char)*p))
		p++;
	if (!*p)
		return NULL;
	q = p + strlen(p) - 1;
	while ((q != p) && isspace((unsigned char)*q))
		q--;
	if (p != q)
		q[1] = 0;
	if (!*p)
		return NULL;
	return p;
}

static const char hex_digits[] = "0123456789ABCDEF";

char *
hex_to_string(const unsigned char *buffer, long len)
{
	CBB cbb;
	CBS cbs;
	uint8_t *out = NULL;
	uint8_t c;
	size_t out_len;

	if (!CBB_init(&cbb, 0))
		goto err;

	if (len < 0)
		goto err;

	CBS_init(&cbs, buffer, len);
	while (CBS_len(&cbs) > 0) {
		if (!CBS_get_u8(&cbs, &c))
			goto err;
		if (!CBB_add_u8(&cbb, hex_digits[c >> 4]))
			goto err;
		if (!CBB_add_u8(&cbb, hex_digits[c & 0xf]))
			goto err;
		if (CBS_len(&cbs) > 0) {
			if (!CBB_add_u8(&cbb, ':'))
				goto err;
		}
	}

	if (!CBB_add_u8(&cbb, '\0'))
		goto err;

	if (!CBB_finish(&cbb, &out, &out_len))
		goto err;

 err:
	CBB_cleanup(&cbb);

	return out;
}
LCRYPTO_ALIAS(hex_to_string);

static int
x509_skip_colons_cbs(CBS *cbs)
{
	uint8_t c;

	while (CBS_len(cbs) > 0) {
		if (!CBS_peek_u8(cbs, &c))
			return 0;
		if (c != ':')
			return 1;
		if (!CBS_get_u8(cbs, &c))
			return 0;
	}

	return 1;
}

static int
x509_get_xdigit_nibble_cbs(CBS *cbs, uint8_t *out_nibble)
{
	uint8_t c;

	if (!CBS_get_u8(cbs, &c))
		return 0;

	if (c >= '0' && c <= '9') {
		*out_nibble = c - '0';
		return 1;
	}
	if (c >= 'a' && c <= 'f') {
		*out_nibble = c - 'a' + 10;
		return 1;
	}
	if (c >= 'A' && c <= 'F') {
		*out_nibble = c - 'A' + 10;
		return 1;
	}

	X509V3error(X509V3_R_ILLEGAL_HEX_DIGIT);
	return 0;
}

unsigned char *
string_to_hex(const char *str, long *len)
{
	CBB cbb;
	CBS cbs;
	uint8_t *out = NULL;
	size_t out_len;
	uint8_t hi, lo;

	*len = 0;

	if (!CBB_init(&cbb, 0))
		goto err;

	if (str == NULL) {
		X509V3error(X509V3_R_INVALID_NULL_ARGUMENT);
		goto err;
	}

	CBS_init(&cbs, str, strlen(str));
	while (CBS_len(&cbs) > 0) {
		/*
		 * Skipping only a single colon between two pairs of digits
		 * would make more sense - history...
		 */
		if (!x509_skip_colons_cbs(&cbs))
			goto err;
		/* Another historic idiocy. */
		if (CBS_len(&cbs) == 0)
			break;
		if (!x509_get_xdigit_nibble_cbs(&cbs, &hi))
			goto err;
		if (CBS_len(&cbs) == 0) {
			X509V3error(X509V3_R_ODD_NUMBER_OF_DIGITS);
			goto err;
		}
		if (!x509_get_xdigit_nibble_cbs(&cbs, &lo))
			goto err;
		if (!CBB_add_u8(&cbb, hi << 4 | lo))
			goto err;
	}

	if (!CBB_finish(&cbb, &out, &out_len))
		goto err;
	if (out_len > LONG_MAX) {
		freezero(out, out_len);
		out = NULL;
		goto err;
	}

	*len = out_len;

 err:
	CBB_cleanup(&cbb);

	return out;
}
LCRYPTO_ALIAS(string_to_hex);

/* V2I name comparison function: returns zero if 'name' matches
 * cmp or cmp.*
 */

int
name_cmp(const char *name, const char *cmp)
{
	int len, ret;
	char c;

	len = strlen(cmp);
	if ((ret = strncmp(name, cmp, len)))
		return ret;
	c = name[len];
	if (!c || (c=='.'))
		return 0;
	return 1;
}

static int
sk_strcmp(const char * const *a, const char * const *b)
{
	return strcmp(*a, *b);
}

STACK_OF(OPENSSL_STRING) *
X509_get1_email(X509 *x)
{
	GENERAL_NAMES *gens;
	STACK_OF(OPENSSL_STRING) *ret;

	gens = X509_get_ext_d2i(x, NID_subject_alt_name, NULL, NULL);
	ret = get_email(X509_get_subject_name(x), gens);
	sk_GENERAL_NAME_pop_free(gens, GENERAL_NAME_free);
	return ret;
}
LCRYPTO_ALIAS(X509_get1_email);

STACK_OF(OPENSSL_STRING) *
X509_get1_ocsp(X509 *x)
{
	AUTHORITY_INFO_ACCESS *info;
	STACK_OF(OPENSSL_STRING) *ret = NULL;
	int i;

	info = X509_get_ext_d2i(x, NID_info_access, NULL, NULL);
	if (!info)
		return NULL;
	for (i = 0; i < sk_ACCESS_DESCRIPTION_num(info); i++) {
		ACCESS_DESCRIPTION *ad = sk_ACCESS_DESCRIPTION_value(info, i);
		if (OBJ_obj2nid(ad->method) == NID_ad_OCSP) {
			if (ad->location->type == GEN_URI) {
				if (!append_ia5(&ret,
				    ad->location->d.uniformResourceIdentifier))
					break;
			}
		}
	}
	AUTHORITY_INFO_ACCESS_free(info);
	return ret;
}
LCRYPTO_ALIAS(X509_get1_ocsp);

STACK_OF(OPENSSL_STRING) *
X509_REQ_get1_email(X509_REQ *x)
{
	GENERAL_NAMES *gens;
	STACK_OF(X509_EXTENSION) *exts;
	STACK_OF(OPENSSL_STRING) *ret;

	exts = X509_REQ_get_extensions(x);
	gens = X509V3_get_d2i(exts, NID_subject_alt_name, NULL, NULL);
	ret = get_email(X509_REQ_get_subject_name(x), gens);
	sk_GENERAL_NAME_pop_free(gens, GENERAL_NAME_free);
	sk_X509_EXTENSION_pop_free(exts, X509_EXTENSION_free);
	return ret;
}
LCRYPTO_ALIAS(X509_REQ_get1_email);


static STACK_OF(OPENSSL_STRING) *
get_email(X509_NAME *name, GENERAL_NAMES *gens)
{
	STACK_OF(OPENSSL_STRING) *ret = NULL;
	X509_NAME_ENTRY *ne;
	ASN1_IA5STRING *email;
	GENERAL_NAME *gen;
	int i;

	/* Now add any email address(es) to STACK */
	i = -1;

	/* First supplied X509_NAME */
	while ((i = X509_NAME_get_index_by_NID(name,
	    NID_pkcs9_emailAddress, i)) >= 0) {
		ne = X509_NAME_get_entry(name, i);
		email = X509_NAME_ENTRY_get_data(ne);
		if (!append_ia5(&ret, email))
			return NULL;
	}
	for (i = 0; i < sk_GENERAL_NAME_num(gens); i++) {
		gen = sk_GENERAL_NAME_value(gens, i);
		if (gen->type != GEN_EMAIL)
			continue;
		if (!append_ia5(&ret, gen->d.ia5))
			return NULL;
	}
	return ret;
}

static void
str_free(OPENSSL_STRING str)
{
	free(str);
}

static int
append_ia5(STACK_OF(OPENSSL_STRING) **sk, ASN1_IA5STRING *email)
{
	char *emtmp;

	/* First some sanity checks */
	if (email->type != V_ASN1_IA5STRING)
		return 1;
	if (!email->data || !email->length)
		return 1;
	if (!*sk)
		*sk = sk_OPENSSL_STRING_new(sk_strcmp);
	if (!*sk)
		return 0;
	/* Don't add duplicates */
	if (sk_OPENSSL_STRING_find(*sk, (char *)email->data) != -1)
		return 1;
	emtmp = strdup((char *)email->data);
	if (!emtmp || !sk_OPENSSL_STRING_push(*sk, emtmp)) {
		X509_email_free(*sk);
		*sk = NULL;
		return 0;
	}
	return 1;
}

void
X509_email_free(STACK_OF(OPENSSL_STRING) *sk)
{
	sk_OPENSSL_STRING_pop_free(sk, str_free);
}
LCRYPTO_ALIAS(X509_email_free);

typedef int (*equal_fn)(const unsigned char *pattern, size_t pattern_len,
    const unsigned char *subject, size_t subject_len, unsigned int flags);

/* Skip pattern prefix to match "wildcard" subject */
static void
skip_prefix(const unsigned char **p, size_t *plen, const unsigned char *subject,
    size_t subject_len, unsigned int flags)
{
	const unsigned char *pattern = *p;
	size_t pattern_len = *plen;

	/*
	 * If subject starts with a leading '.' followed by more octets, and
	 * pattern is longer, compare just an equal-length suffix with the
	 * full subject (starting at the '.'), provided the prefix contains
	 * no NULs.
	 */
	if ((flags & _X509_CHECK_FLAG_DOT_SUBDOMAINS) == 0)
		return;

	while (pattern_len > subject_len && *pattern) {
		if ((flags & X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS) &&
		    *pattern == '.')
			break;
		++pattern;
		--pattern_len;
	}

	/* Skip if entire prefix acceptable */
	if (pattern_len == subject_len) {
		*p = pattern;
		*plen = pattern_len;
	}
}

/*
 * Open/BoringSSL uses memcmp for "equal_case" while their
 * "equal_nocase" function is a hand-rolled strncasecmp that does not
 * allow \0 in the pattern. Since an embedded \0 is likely a sign of
 * problems, we simply don't allow it in either case, and then we use
 * standard libc functions.
 */

/* Compare using strncasecmp */
static int
equal_nocase(const unsigned char *pattern, size_t pattern_len,
    const unsigned char *subject, size_t subject_len, unsigned int flags)
{
	if (memchr(pattern, '\0', pattern_len) != NULL)
		return 0;
	if (memchr(subject, '\0', subject_len) != NULL)
		return 0;
	skip_prefix(&pattern, &pattern_len, subject, subject_len, flags);
	if (pattern_len != subject_len)
		return 0;
	return (strncasecmp(pattern, subject, pattern_len) == 0);
}

/* Compare using strncmp. */
static int
equal_case(const unsigned char *pattern, size_t pattern_len,
    const unsigned char *subject, size_t subject_len, unsigned int flags)
{
	if (memchr(pattern, 0, pattern_len) != NULL)
		return 0;
	if (memchr(subject, 0, subject_len) != NULL)
		return 0;
	skip_prefix(&pattern, &pattern_len, subject, subject_len, flags);
	if (pattern_len != subject_len)
		return 0;
	return (strncmp(pattern, subject, pattern_len) == 0);
}

/*
 * RFC 5280, section 7.5, requires that only the domain is compared in a
 * case-insensitive manner.
 */
static int
equal_email(const unsigned char *a, size_t a_len, const unsigned char *b,
    size_t b_len, unsigned int unused_flags)
{
	size_t pos = a_len;
	if (a_len != b_len)
		return 0;
	/*
	 * We search backwards for the '@' character, so that we do not have to
	 * deal with quoted local-parts.  The domain part is compared in a
	 * case-insensitive manner.
	 */
	while (pos > 0) {
		pos--;
		if (a[pos] == '@' || b[pos] == '@') {
			if (!equal_nocase(a + pos, a_len - pos, b + pos,
			    a_len - pos, 0))
				return 0;
			break;
		}
	}
	if (pos == 0)
		pos = a_len;
	return equal_case(a, pos, b, pos, 0);
}

/*
 * Compare the prefix and suffix with the subject, and check that the
 * characters in-between are valid.
 */
static int
wildcard_match(const unsigned char *prefix, size_t prefix_len,
    const unsigned char *suffix, size_t suffix_len,
    const unsigned char *subject, size_t subject_len, unsigned int flags)
{
	const unsigned char *wildcard_start;
	const unsigned char *wildcard_end;
	const unsigned char *p;
	int allow_multi = 0;
	int allow_idna = 0;

	if (subject_len < prefix_len + suffix_len)
		return 0;
	if (!equal_nocase(prefix, prefix_len, subject, prefix_len, flags))
		return 0;
	wildcard_start = subject + prefix_len;
	wildcard_end = subject + (subject_len - suffix_len);
	if (!equal_nocase(wildcard_end, suffix_len, suffix, suffix_len, flags))
		return 0;
	/*
	 * If the wildcard makes up the entire first label, it must match at
	 * least one character.
	 */
	if (prefix_len == 0 && *suffix == '.') {
		if (wildcard_start == wildcard_end)
			return 0;
		allow_idna = 1;
		if (flags & X509_CHECK_FLAG_MULTI_LABEL_WILDCARDS)
			allow_multi = 1;
	}
	/* IDNA labels cannot match partial wildcards */
	if (!allow_idna &&
	    subject_len >= 4
	    && strncasecmp((char *)subject, "xn--", 4) == 0)
		return 0;
	/* The wildcard may match a literal '*' */
	if (wildcard_end == wildcard_start + 1 && *wildcard_start == '*')
		return 1;
	/*
	 * Check that the part matched by the wildcard contains only
	 * permitted characters and only matches a single label unless
	 * allow_multi is set.
	 */
	for (p = wildcard_start; p != wildcard_end; ++p)
		if (!(('0' <= *p && *p <= '9') || ('A' <= *p && *p <= 'Z') ||
		    ('a' <= *p && *p <= 'z') || *p == '-' ||
		    (allow_multi && *p == '.')))
			return 0;
	return 1;
}

#define LABEL_START     (1 << 0)
#define LABEL_END       (1 << 1)
#define LABEL_HYPHEN    (1 << 2)
#define LABEL_IDNA      (1 << 3)

static const unsigned char *
valid_star(const unsigned char *p, size_t len, unsigned int flags)
{
	const unsigned char *star = 0;
	size_t i;
	int state = LABEL_START;
	int dots = 0;
	for (i = 0; i < len; ++i) {
		/*
		 * Locate first and only legal wildcard, either at the start
		 * or end of a non-IDNA first and not final label.
		 */
		if (p[i] == '*') {
			int atstart = (state & LABEL_START);
			int atend = (i == len - 1 || p[i + 1] == '.');
			/*
			 * At most one wildcard per pattern.
			 * No wildcards in IDNA labels.
			 * No wildcards after the first label.
			 */
			if (star != NULL || (state & LABEL_IDNA) != 0 || dots)
				return NULL;
			/* Only full-label '*.example.com' wildcards? */
			if ((flags & X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS)
			    && (!atstart || !atend))
				return NULL;
			/* No 'foo*bar' wildcards */
			if (!atstart && !atend)
				return NULL;
			star = &p[i];
			state &= ~LABEL_START;
		} else if ((state & LABEL_START) != 0) {
			/*
			 * At the start of a label, skip any "xn--" and
			 * remain in the LABEL_START state, but set the
			 * IDNA label state
			 */
			if ((state & LABEL_IDNA) == 0 && len - i >= 4
			    && strncasecmp((char *)&p[i], "xn--", 4) == 0) {
				i += 3;
				state |= LABEL_IDNA;
				continue;
			}
			/* Labels must start with a letter or digit */
			state &= ~LABEL_START;
			if (('a' <= p[i] && p[i] <= 'z')
			    || ('A' <= p[i] && p[i] <= 'Z')
			    || ('0' <= p[i] && p[i] <= '9'))
				continue;
			return NULL;
		} else if (('a' <= p[i] && p[i] <= 'z')
		    || ('A' <= p[i] && p[i] <= 'Z')
		    || ('0' <= p[i] && p[i] <= '9')) {
			state &= LABEL_IDNA;
			continue;
		} else if (p[i] == '.') {
			if (state & (LABEL_HYPHEN | LABEL_START))
				return NULL;
			state = LABEL_START;
			++dots;
		} else if (p[i] == '-') {
			/* no domain/subdomain starts with '-' */
			if ((state & LABEL_START) != 0)
				return NULL;
			state |= LABEL_HYPHEN;
		} else
			return NULL;
	}

	/*
	 * The final label must not end in a hyphen or ".", and
	 * there must be at least two dots after the star.
	 */
	if ((state & (LABEL_START | LABEL_HYPHEN)) != 0 || dots < 2)
		return NULL;
	return star;
}

/* Compare using wildcards. */
static int
equal_wildcard(const unsigned char *pattern, size_t pattern_len,
    const unsigned char *subject, size_t subject_len, unsigned int flags)
{
	const unsigned char *star = NULL;

	/*
	 * Subject names starting with '.' can only match a wildcard pattern
	 * via a subject sub-domain pattern suffix match.
	 */
	if (!(subject_len > 1 && subject[0] == '.'))
		star = valid_star(pattern, pattern_len, flags);
	if (star == NULL)
		return equal_nocase(pattern, pattern_len,
		    subject, subject_len, flags);
	return wildcard_match(pattern, star - pattern,
	    star + 1, (pattern + pattern_len) - star - 1,
	    subject, subject_len, flags);
}

/*
 * Compare an ASN1_STRING to a supplied string. If they match return 1. If
 * cmp_type > 0 only compare if string matches the type, otherwise convert it
 * to UTF8.
 */

static int
do_check_string(ASN1_STRING *a, int cmp_type, equal_fn equal,
    unsigned int flags, const char *b, size_t blen, char **peername)
{
	int rv = 0;

	if (!a->data || !a->length)
		return 0;
	if (cmp_type > 0) {
		if (cmp_type != a->type)
			return 0;
		if (cmp_type == V_ASN1_IA5STRING)
			rv = equal(a->data, a->length, (unsigned char *)b,
			    blen, flags);
		else if (a->length == (int)blen && !memcmp(a->data, b, blen))
			rv = 1;
		if (rv > 0 && peername &&
		    (*peername = strndup((char *)a->data, a->length)) == NULL)
			rv = -1;
	} else {
		int astrlen;
		unsigned char *astr = NULL;
		astrlen = ASN1_STRING_to_UTF8(&astr, a);
		if (astrlen < 0)
			return -1;
		rv = equal(astr, astrlen, (unsigned char *)b, blen, flags);
		if (rv > 0 && peername &&
		    (*peername = strndup((char *)astr, astrlen)) == NULL)
			rv = -1;
		free(astr);
	}
	return rv;
}

static int
do_x509_check(X509 *x, const char *chk, size_t chklen, unsigned int flags,
    int check_type, char **peername)
{
	GENERAL_NAMES *gens = NULL;
	X509_NAME *name = NULL;
	size_t i;
	int j;
	int cnid = NID_undef;
	int alt_type;
	int san_present = 0;
	int rv = 0;
	equal_fn equal;

	/* See below, this flag is internal-only */
	flags &= ~_X509_CHECK_FLAG_DOT_SUBDOMAINS;
	if (check_type == GEN_EMAIL) {
		cnid = NID_pkcs9_emailAddress;
		alt_type = V_ASN1_IA5STRING;
		equal = equal_email;
	} else if (check_type == GEN_DNS) {
		if (!(flags & X509_CHECK_FLAG_NEVER_CHECK_SUBJECT))
			cnid = NID_commonName;
		/* Implicit client-side DNS sub-domain pattern */
		if (chklen > 1 && chk[0] == '.')
			flags |= _X509_CHECK_FLAG_DOT_SUBDOMAINS;
		alt_type = V_ASN1_IA5STRING;
		if (flags & X509_CHECK_FLAG_NO_WILDCARDS)
			equal = equal_nocase;
		else
			equal = equal_wildcard;
	} else {
		alt_type = V_ASN1_OCTET_STRING;
		equal = equal_case;
	}

	gens = X509_get_ext_d2i(x, NID_subject_alt_name, NULL, NULL);
	if (gens != NULL) {
		for (i = 0; i < sk_GENERAL_NAME_num(gens); i++) {
			GENERAL_NAME *gen;
			ASN1_STRING *cstr;
			gen = sk_GENERAL_NAME_value(gens, i);
			if (gen->type != check_type)
				continue;
			san_present = 1;
			if (check_type == GEN_EMAIL)
				cstr = gen->d.rfc822Name;
			else if (check_type == GEN_DNS)
				cstr = gen->d.dNSName;
			else
				cstr = gen->d.iPAddress;
			/* Positive on success, negative on error! */
			if ((rv = do_check_string(cstr, alt_type, equal, flags,
			    chk, chklen, peername)) != 0)
				break;
		}
		GENERAL_NAMES_free(gens);
		if (rv != 0)
			return rv;
		if (cnid == NID_undef ||
		    (san_present &&
		    !(flags & X509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT)))
			return 0;
	}

	/* We're done if CN-ID is not pertinent */
	if (cnid == NID_undef)
		return 0;

	j = -1;
	name = X509_get_subject_name(x);
	while ((j = X509_NAME_get_index_by_NID(name, cnid, j)) >= 0) {
		X509_NAME_ENTRY *ne;
		ASN1_STRING *str;
		if ((ne = X509_NAME_get_entry(name, j)) == NULL)
			return -1;
		if ((str = X509_NAME_ENTRY_get_data(ne)) == NULL)
			return -1;
		/* Positive on success, negative on error! */
		if ((rv = do_check_string(str, -1, equal, flags,
			 chk, chklen, peername)) != 0)
			return rv;
	}
	return 0;
}

int
X509_check_host(X509 *x, const char *chk, size_t chklen, unsigned int flags,
    char **peername)
{
	if (chk == NULL)
		return -2;
	if (chklen == 0)
		chklen = strlen(chk);
	else if (memchr(chk, '\0', chklen))
		return -2;
	return do_x509_check(x, chk, chklen, flags, GEN_DNS, peername);
}
LCRYPTO_ALIAS(X509_check_host);

int
X509_check_email(X509 *x, const char *chk, size_t chklen, unsigned int flags)
{
	if (chk == NULL)
		return -2;
	if (chklen == 0)
		chklen = strlen(chk);
	else if (memchr(chk, '\0', chklen))
		return -2;
	return do_x509_check(x, chk, chklen, flags, GEN_EMAIL, NULL);
}
LCRYPTO_ALIAS(X509_check_email);

int
X509_check_ip(X509 *x, const unsigned char *chk, size_t chklen,
    unsigned int flags)
{
	if (chk == NULL)
		return -2;
	return do_x509_check(x, (char *)chk, chklen, flags, GEN_IPADD, NULL);
}
LCRYPTO_ALIAS(X509_check_ip);

int
X509_check_ip_asc(X509 *x, const char *ipasc, unsigned int flags)
{
	unsigned char ipout[16];
	size_t iplen;

	if (ipasc == NULL)
		return -2;
	iplen = (size_t)a2i_ipadd(ipout, ipasc);
	if (iplen == 0)
		return -2;
	return do_x509_check(x, (char *)ipout, iplen, flags, GEN_IPADD, NULL);
}
LCRYPTO_ALIAS(X509_check_ip_asc);

/* Convert IP addresses both IPv4 and IPv6 into an
 * OCTET STRING compatible with RFC3280.
 */

ASN1_OCTET_STRING *
a2i_IPADDRESS(const char *ipasc)
{
	unsigned char ipout[16];
	ASN1_OCTET_STRING *ret;
	int iplen;

	/* If string contains a ':' assume IPv6 */

	iplen = a2i_ipadd(ipout, ipasc);

	if (!iplen)
		return NULL;

	ret = ASN1_OCTET_STRING_new();
	if (!ret)
		return NULL;
	if (!ASN1_OCTET_STRING_set(ret, ipout, iplen)) {
		ASN1_OCTET_STRING_free(ret);
		return NULL;
	}
	return ret;
}
LCRYPTO_ALIAS(a2i_IPADDRESS);

ASN1_OCTET_STRING *
a2i_IPADDRESS_NC(const char *ipasc)
{
	ASN1_OCTET_STRING *ret = NULL;
	unsigned char ipout[32];
	char *iptmp = NULL, *p;
	int iplen1, iplen2;

	p = strchr(ipasc, '/');
	if (!p)
		return NULL;
	iptmp = strdup(ipasc);
	if (!iptmp)
		return NULL;
	p = iptmp + (p - ipasc);
	*p++ = 0;

	iplen1 = a2i_ipadd(ipout, iptmp);

	if (!iplen1)
		goto err;

	iplen2 = a2i_ipadd(ipout + iplen1, p);

	free(iptmp);
	iptmp = NULL;

	if (!iplen2 || (iplen1 != iplen2))
		goto err;

	ret = ASN1_OCTET_STRING_new();
	if (!ret)
		goto err;
	if (!ASN1_OCTET_STRING_set(ret, ipout, iplen1 + iplen2))
		goto err;

	return ret;

 err:
	free(iptmp);
	if (ret)
		ASN1_OCTET_STRING_free(ret);
	return NULL;
}
LCRYPTO_ALIAS(a2i_IPADDRESS_NC);


int
a2i_ipadd(unsigned char *ipout, const char *ipasc)
{
	/* If string contains a ':' assume IPv6 */

	if (strchr(ipasc, ':')) {
		if (!ipv6_from_asc(ipout, ipasc))
			return 0;
		return 16;
	} else {
		if (!ipv4_from_asc(ipout, ipasc))
			return 0;
		return 4;
	}
}
LCRYPTO_ALIAS(a2i_ipadd);

static int
ipv4_from_asc(unsigned char *v4, const char *in)
{
	int a0, a1, a2, a3;
	if (sscanf(in, "%d.%d.%d.%d", &a0, &a1, &a2, &a3) != 4)
		return 0;
	if ((a0 < 0) || (a0 > 255) || (a1 < 0) || (a1 > 255) ||
	    (a2 < 0) || (a2 > 255) || (a3 < 0) || (a3 > 255))
		return 0;
	v4[0] = a0;
	v4[1] = a1;
	v4[2] = a2;
	v4[3] = a3;
	return 1;
}

typedef struct {
	/* Temporary store for IPV6 output */
	unsigned char tmp[16];
	/* Total number of bytes in tmp */
	int total;
	/* The position of a zero (corresponding to '::') */
	int zero_pos;
	/* Number of zeroes */
	int zero_cnt;
} IPV6_STAT;


static int
ipv6_from_asc(unsigned char *v6, const char *in)
{
	IPV6_STAT v6stat;

	v6stat.total = 0;
	v6stat.zero_pos = -1;
	v6stat.zero_cnt = 0;

	/*
	 * Treat the IPv6 representation as a list of values separated by ':'.
	 * The presence of a '::' will parse as one (e.g., "2001:db8::1"),
	 * two (e.g., "2001:db8::") or three (e.g., "::") zero length elements.
	 */
	if (!CONF_parse_list(in, ':', 0, ipv6_cb, &v6stat))
		return 0;

	/* Now for some sanity checks */

	if (v6stat.zero_pos == -1) {
		/* If no '::' must have exactly 16 bytes */
		if (v6stat.total != 16)
			return 0;
	} else {
		/* If '::' must have less than 16 bytes */
		if (v6stat.total == 16)
			return 0;
		/* More than three zeroes is an error */
		if (v6stat.zero_cnt > 3)
			return 0;
		/* Can only have three zeroes if nothing else present */
		else if (v6stat.zero_cnt == 3) {
			if (v6stat.total > 0)
				return 0;
		}
		/* Can only have two zeroes if at start or end */
		else if (v6stat.zero_cnt == 2) {
			if ((v6stat.zero_pos != 0) &&
			    (v6stat.zero_pos != v6stat.total))
				return 0;
		} else
			/* Can only have one zero if *not* start or end */
		{
			if ((v6stat.zero_pos == 0) ||
			    (v6stat.zero_pos == v6stat.total))
				return 0;
		}
	}

	/* Format result */

	if (v6stat.zero_pos >= 0) {
		/* Copy initial part */
		memcpy(v6, v6stat.tmp, v6stat.zero_pos);
		/* Zero middle */
		memset(v6 + v6stat.zero_pos, 0, 16 - v6stat.total);
		/* Copy final part */
		if (v6stat.total != v6stat.zero_pos)
			memcpy(v6 + v6stat.zero_pos + 16 - v6stat.total,
			    v6stat.tmp + v6stat.zero_pos,
			    v6stat.total - v6stat.zero_pos);
	} else
		memcpy(v6, v6stat.tmp, 16);

	return 1;
}

static int
ipv6_cb(const char *elem, int len, void *usr)
{
	IPV6_STAT *s = usr;

	/* Error if 16 bytes written */
	if (s->total == 16)
		return 0;
	if (len == 0) {
		/* Zero length element, corresponds to '::' */
		if (s->zero_pos == -1)
			s->zero_pos = s->total;
		/* If we've already got a :: its an error */
		else if (s->zero_pos != s->total)
			return 0;
		s->zero_cnt++;
	} else {
		/* If more than 4 characters could be final a.b.c.d form */
		if (len > 4) {
			/* Need at least 4 bytes left */
			if (s->total > 12)
				return 0;
			/* Must be end of string */
			if (elem[len])
				return 0;
			if (!ipv4_from_asc(s->tmp + s->total, elem))
				return 0;
			s->total += 4;
		} else {
			if (!ipv6_hex(s->tmp + s->total, elem, len))
				return 0;
			s->total += 2;
		}
	}
	return 1;
}

/* Convert a string of up to 4 hex digits into the corresponding
 * IPv6 form.
 */

static int
ipv6_hex(unsigned char *out, const char *in, int inlen)
{
	unsigned char c;
	unsigned int num = 0;

	if (inlen > 4)
		return 0;
	while (inlen--) {
		c = *in++;
		num <<= 4;
		if ((c >= '0') && (c <= '9'))
			num |= c - '0';
		else if ((c >= 'A') && (c <= 'F'))
			num |= c - 'A' + 10;
		else if ((c >= 'a') && (c <= 'f'))
			num |=  c - 'a' + 10;
		else
			return 0;
	}
	out[0] = num >> 8;
	out[1] = num & 0xff;
	return 1;
}

int
X509V3_NAME_from_section(X509_NAME *nm, STACK_OF(CONF_VALUE)*dn_sk,
    unsigned long chtype)
{
	CONF_VALUE *v;
	int i, mval;
	char *p, *type;

	if (!nm)
		return 0;

	for (i = 0; i < sk_CONF_VALUE_num(dn_sk); i++) {
		v = sk_CONF_VALUE_value(dn_sk, i);
		type = v->name;
		/* Skip past any leading X. X: X, etc to allow for
		 * multiple instances
		 */
		for (p = type; *p; p++)
			if ((*p == ':') || (*p == ',') || (*p == '.')) {
				p++;
				if (*p)
					type = p;
				break;
			}
		if (*type == '+') {
			mval = -1;
			type++;
		} else
			mval = 0;
		if (!X509_NAME_add_entry_by_txt(nm, type, chtype,
		    (unsigned char *) v->value, -1, -1, mval))
			return 0;
	}
	return 1;
}
LCRYPTO_ALIAS(X509V3_NAME_from_section);