/* $OpenBSD: x509_utl.c,v 1.28 2026/01/12 22:08:34 tb 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/x509v3.h>

#include "bytestring.h"
#include "conf_local.h"
#include "err_local.h"

/*
 * Match reference identifiers starting with "." to any sub-domain. This
 * flag is set implicitly when the subject reference identity is a DNS name.
 */
#define _X509_CHECK_FLAG_DOT_SUBDOMAINS 0x8000

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) **out_extlist)
{
        STACK_OF(CONF_VALUE) *extlist = NULL;
        CONF_VALUE *conf_value = NULL;
        int ret = 0;

        if ((conf_value = calloc(1, sizeof(*conf_value))) == NULL) {
                X509V3error(ERR_R_MALLOC_FAILURE);
                goto err;
        }
        if (name != NULL) {
                if ((conf_value->name = strdup(name)) == NULL) {
                        X509V3error(ERR_R_MALLOC_FAILURE);
                        goto err;
                }
        }
        if (value != NULL) {
                if ((conf_value->value = strdup(value)) == NULL) {
                        X509V3error(ERR_R_MALLOC_FAILURE);
                        goto err;
                }
        }

        if ((extlist = *out_extlist) == NULL)
                extlist = sk_CONF_VALUE_new_null();
        if (extlist == NULL) {
                X509V3error(ERR_R_MALLOC_FAILURE);
                goto err;
        }

        if (!sk_CONF_VALUE_push(extlist, conf_value)) {
                X509V3error(ERR_R_MALLOC_FAILURE);
                goto err;
        }
        conf_value = NULL;

        *out_extlist = extlist;
        extlist = NULL;

        ret = 1;

 err:
        if (extlist != *out_extlist)
                sk_CONF_VALUE_pop_free(extlist, X509V3_conf_free);
        X509V3_conf_free(conf_value);

        return ret;
}

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);
}

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);
}

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;
}

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;
}

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;
}

#define HDR_NAME        1
#define HDR_VALUE       2

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;
                                }
                                if (!X509V3_add_value(ntmp, NULL, &values))
                                        goto err;
                        }
                        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;
                                }
                                if (!X509V3_add_value(ntmp, vtmp, &values))
                                        goto err;
                                ntmp = NULL;
                                q = p + 1;
                        }

                }
        }

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