/*

 * Copyright 2003-2021 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the OpenSSL license (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy

 * in the file LICENSE in the source distribution or at

 * https://www.openssl.org/source/license.html

 */

#include "internal/cryptlib.h"

#include "internal/numbers.h"

#include <stdio.h>

#include "crypto/asn1.h"

#include <openssl/asn1t.h>

#include <openssl/conf.h>

#include <openssl/x509v3.h>

#include "crypto/x509.h"

#include "ext_dat.h"

static void *v2i_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method,

                                  X509V3_CTX *ctx,

                                  STACK_OF(CONF_VALUE) *nval);

static int i2r_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method, void *a,

                                BIO *bp, int ind);

static int do_i2r_name_constraints(const X509V3_EXT_METHOD *method,

                                   STACK_OF(GENERAL_SUBTREE) *trees, BIO *bp,

                                   int ind, const char *name);

static int print_nc_ipadd(BIO *bp, ASN1_OCTET_STRING *ip);

static int nc_match(GENERAL_NAME *gen, NAME_CONSTRAINTS *nc);

static int nc_match_single(GENERAL_NAME *sub, GENERAL_NAME *gen);

static int nc_dn(X509_NAME *sub, X509_NAME *nm);

static int nc_dns(ASN1_IA5STRING *sub, ASN1_IA5STRING *dns);

static int nc_email(ASN1_IA5STRING *sub, ASN1_IA5STRING *eml);

static int nc_uri(ASN1_IA5STRING *uri, ASN1_IA5STRING *base);

static int nc_ip(ASN1_OCTET_STRING *ip, ASN1_OCTET_STRING *base);

const X509V3_EXT_METHOD v3_name_constraints = {

    NID_name_constraints, 0,

    ASN1_ITEM_ref(NAME_CONSTRAINTS),

    0, 0, 0, 0,

    0, 0,

    0, v2i_NAME_CONSTRAINTS,

    i2r_NAME_CONSTRAINTS, 0,

    NULL

};

ASN1_SEQUENCE(GENERAL_SUBTREE) = {

        ASN1_SIMPLE(GENERAL_SUBTREE, base, GENERAL_NAME),

        ASN1_IMP_OPT(GENERAL_SUBTREE, minimum, ASN1_INTEGER, 0),

        ASN1_IMP_OPT(GENERAL_SUBTREE, maximum, ASN1_INTEGER, 1)

} ASN1_SEQUENCE_END(GENERAL_SUBTREE)

ASN1_SEQUENCE(NAME_CONSTRAINTS) = {

        ASN1_IMP_SEQUENCE_OF_OPT(NAME_CONSTRAINTS, permittedSubtrees,

                                                        GENERAL_SUBTREE, 0),

        ASN1_IMP_SEQUENCE_OF_OPT(NAME_CONSTRAINTS, excludedSubtrees,

                                                        GENERAL_SUBTREE, 1),

} ASN1_SEQUENCE_END(NAME_CONSTRAINTS)

IMPLEMENT_ASN1_ALLOC_FUNCTIONS(GENERAL_SUBTREE)

IMPLEMENT_ASN1_ALLOC_FUNCTIONS(NAME_CONSTRAINTS)

#define IA5_OFFSET_LEN(ia5base, offset) \

    ((ia5base)->length - ((unsigned char *)(offset) - (ia5base)->data))

/* Like memchr but for ASN1_IA5STRING. Additionally you can specify the

 * starting point to search from

 */

# define ia5memchr(str, start, c) memchr(start, c, IA5_OFFSET_LEN(str, start))

/* Like memrrchr but for ASN1_IA5STRING */

static char *ia5memrchr(ASN1_IA5STRING *str, int c)

{

    int i;

    for (i = str->length; i > 0 && str->data[i - 1] != c; i--);

    if (i == 0)

        return NULL;

    return (char *)&str->data[i - 1];

}

/*

 * We cannot use strncasecmp here because that applies locale specific rules. It

 * also doesn't work with ASN1_STRINGs that may have embedded NUL characters.

 * For example in Turkish 'I' is not the uppercase character for 'i'. We need to

 * do a simple ASCII case comparison ignoring the locale (that is why we use

 * numeric constants below).

 */

static int ia5ncasecmp(const char *s1, const char *s2, size_t n)

{

    for (; n > 0; n--, s1++, s2++) {

        if (*s1 != *s2) {

            unsigned char c1 = (unsigned char)*s1, c2 = (unsigned char)*s2;

            /* Convert to lower case */

            if (c1 >= 0x41 /* A */ && c1 <= 0x5A /* Z */)

                c1 += 0x20;

            if (c2 >= 0x41 /* A */ && c2 <= 0x5A /* Z */)

                c2 += 0x20;

            if (c1 == c2)

                continue;

            if (c1 < c2)

                return -1;

            /* c1 > c2 */

            return 1;

        }

    }

    return 0;

}

static void *v2i_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method,

                                  X509V3_CTX *ctx, STACK_OF(CONF_VALUE) *nval)

{

    int i;

    CONF_VALUE tval, *val;

    STACK_OF(GENERAL_SUBTREE) **ptree = NULL;

    NAME_CONSTRAINTS *ncons = NULL;

    GENERAL_SUBTREE *sub = NULL;

    ncons = NAME_CONSTRAINTS_new();

    if (ncons == NULL)

        goto memerr;

    for (i = 0; i < sk_CONF_VALUE_num(nval); i++) {

        val = sk_CONF_VALUE_value(nval, i);

        if (strncmp(val->name, "permitted", 9) == 0 && val->name[9]) {

            ptree = &ncons->permittedSubtrees;

            tval.name = val->name + 10;

        } else if (strncmp(val->name, "excluded", 8) == 0 && val->name[8]) {

            ptree = &ncons->excludedSubtrees;

            tval.name = val->name + 9;

        } else {

            X509V3err(X509V3_F_V2I_NAME_CONSTRAINTS, X509V3_R_INVALID_SYNTAX);

            goto err;

        }

        tval.value = val->value;

        sub = GENERAL_SUBTREE_new();

        if (sub == NULL)

            goto memerr;

        if (!v2i_GENERAL_NAME_ex(sub->base, method, ctx, &tval, 1))

            goto err;

        if (*ptree == NULL)

            *ptree = sk_GENERAL_SUBTREE_new_null();

        if (*ptree == NULL || !sk_GENERAL_SUBTREE_push(*ptree, sub))

            goto memerr;

        sub = NULL;

    }

    return ncons;

 memerr:

    X509V3err(X509V3_F_V2I_NAME_CONSTRAINTS, ERR_R_MALLOC_FAILURE);

 err:

    NAME_CONSTRAINTS_free(ncons);

    GENERAL_SUBTREE_free(sub);

    return NULL;

}

static int i2r_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method, void *a,

                                BIO *bp, int ind)

{

    NAME_CONSTRAINTS *ncons = a;

    do_i2r_name_constraints(method, ncons->permittedSubtrees,

                            bp, ind, "Permitted");

    do_i2r_name_constraints(method, ncons->excludedSubtrees,

                            bp, ind, "Excluded");

    return 1;

}

static int do_i2r_name_constraints(const X509V3_EXT_METHOD *method,

                                   STACK_OF(GENERAL_SUBTREE) *trees,

                                   BIO *bp, int ind, const char *name)

{

    GENERAL_SUBTREE *tree;

    int i;

    if (sk_GENERAL_SUBTREE_num(trees) > 0)

        BIO_printf(bp, "%*s%s:\n", ind, "", name);

    for (i = 0; i < sk_GENERAL_SUBTREE_num(trees); i++) {

        tree = sk_GENERAL_SUBTREE_value(trees, i);

        BIO_printf(bp, "%*s", ind + 2, "");

        if (tree->base->type == GEN_IPADD)

            print_nc_ipadd(bp, tree->base->d.ip);

        else

            GENERAL_NAME_print(bp, tree->base);

        BIO_puts(bp, "\n");

    }

    return 1;

}

static int print_nc_ipadd(BIO *bp, ASN1_OCTET_STRING *ip)

{

    int i, len;

    unsigned char *p;

    p = ip->data;

    len = ip->length;

    BIO_puts(bp, "IP:");

    if (len == 8) {

        BIO_printf(bp, "%d.%d.%d.%d/%d.%d.%d.%d",

                   p[0], p[1], p[2], p[3], p[4], p[5], p[6], p[7]);

    } else if (len == 32) {

        for (i = 0; i < 16; i++) {

            BIO_printf(bp, "%X", p[0] << 8 | p[1]);

            p += 2;

            if (i == 7)

                BIO_puts(bp, "/");

            else if (i != 15)

                BIO_puts(bp, ":");

        }

    } else

        BIO_printf(bp, "IP Address:<invalid>");

    return 1;

}

#define NAME_CHECK_MAX (1 << 20)

static int add_lengths(int *out, int a, int b)

{

    /* sk_FOO_num(NULL) returns -1 but is effectively 0 when iterating. */

    if (a < 0)

        a = 0;

    if (b < 0)

        b = 0;

    if (a > INT_MAX - b)

        return 0;

    *out = a + b;

    return 1;

}

/*-

 * Check a certificate conforms to a specified set of constraints.

 * Return values:

 *  X509_V_OK: All constraints obeyed.

 *  X509_V_ERR_PERMITTED_VIOLATION: Permitted subtree violation.

 *  X509_V_ERR_EXCLUDED_VIOLATION: Excluded subtree violation.

 *  X509_V_ERR_SUBTREE_MINMAX: Min or max values present and matching type.

 *  X509_V_ERR_UNSUPPORTED_CONSTRAINT_TYPE:  Unsupported constraint type.

 *  X509_V_ERR_UNSUPPORTED_CONSTRAINT_SYNTAX: bad unsupported constraint syntax.

 *  X509_V_ERR_UNSUPPORTED_NAME_SYNTAX: bad or unsupported syntax of name

 */

int NAME_CONSTRAINTS_check(X509 *x, NAME_CONSTRAINTS *nc)

{

    int r, i, name_count, constraint_count;

    X509_NAME *nm;

    nm = X509_get_subject_name(x);

    /*

     * Guard against certificates with an excessive number of names or

     * constraints causing a computationally expensive name constraints check.

     */

    if (!add_lengths(&name_count, X509_NAME_entry_count(nm),

                     sk_GENERAL_NAME_num(x->altname))

        || !add_lengths(&constraint_count,

                        sk_GENERAL_SUBTREE_num(nc->permittedSubtrees),

                        sk_GENERAL_SUBTREE_num(nc->excludedSubtrees))

        || (name_count > 0 && constraint_count > NAME_CHECK_MAX / name_count))

        return X509_V_ERR_UNSPECIFIED;

    if (X509_NAME_entry_count(nm) > 0) {

        GENERAL_NAME gntmp;

        gntmp.type = GEN_DIRNAME;

        gntmp.d.directoryName = nm;

        r = nc_match(&gntmp, nc);

        if (r != X509_V_OK)

            return r;

        gntmp.type = GEN_EMAIL;

        /* Process any email address attributes in subject name */

        for (i = -1;;) {

            const X509_NAME_ENTRY *ne;

            i = X509_NAME_get_index_by_NID(nm, NID_pkcs9_emailAddress, i);

            if (i == -1)

                break;

            ne = X509_NAME_get_entry(nm, i);

            gntmp.d.rfc822Name = X509_NAME_ENTRY_get_data(ne);

            if (gntmp.d.rfc822Name->type != V_ASN1_IA5STRING)

                return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;

            r = nc_match(&gntmp, nc);

            if (r != X509_V_OK)

                return r;

        }

    }

    for (i = 0; i < sk_GENERAL_NAME_num(x->altname); i++) {

        GENERAL_NAME *gen = sk_GENERAL_NAME_value(x->altname, i);

        r = nc_match(gen, nc);

        if (r != X509_V_OK)

            return r;

    }

    return X509_V_OK;

}

static int cn2dnsid(ASN1_STRING *cn, unsigned char **dnsid, size_t *idlen)

{

    int utf8_length;

    unsigned char *utf8_value;

    int i;

    int isdnsname = 0;

    /* Don't leave outputs uninitialized */

    *dnsid = NULL;

    *idlen = 0;

    /*-

     * Per RFC 6125, DNS-IDs representing internationalized domain names appear

     * in certificates in A-label encoded form:

     *

     *   https://tools.ietf.org/html/rfc6125#section-6.4.2

     *

     * The same applies to CNs which are intended to represent DNS names.

     * However, while in the SAN DNS-IDs are IA5Strings, as CNs they may be

     * needlessly encoded in 16-bit Unicode.  We perform a conversion to UTF-8

     * to ensure that we get an ASCII representation of any CNs that are

     * representable as ASCII, but just not encoded as ASCII.  The UTF-8 form

     * may contain some non-ASCII octets, and that's fine, such CNs are not

     * valid legacy DNS names.

     *

     * Note, 'int' is the return type of ASN1_STRING_to_UTF8() so that's what

     * we must use for 'utf8_length'.

     */

    if ((utf8_length = ASN1_STRING_to_UTF8(&utf8_value, cn)) < 0)

        return X509_V_ERR_OUT_OF_MEM;

    /*

     * Some certificates have had names that include a *trailing* NUL byte.

     * Remove these harmless NUL characters. They would otherwise yield false

     * alarms with the following embedded NUL check.

     */

    while (utf8_length > 0 && utf8_value[utf8_length - 1] == '\0')

        --utf8_length;

    /* Reject *embedded* NULs */

    if (memchr(utf8_value, 0, utf8_length) != NULL) {

        OPENSSL_free(utf8_value);

        return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;

    }

    /*

     * XXX: Deviation from strict DNS name syntax, also check names with '_'

     * Check DNS name syntax, any '-' or '.' must be internal,

     * and on either side of each '.' we can't have a '-' or '.'.

     *

     * If the name has just one label, we don't consider it a DNS name.  This

     * means that "CN=sometld" cannot be precluded by DNS name constraints, but

     * that is not a problem.

     */

    for (i = 0; i < utf8_length; ++i) {

        unsigned char c = utf8_value[i];

        if ((c >= 'a' && c <= 'z')

            || (c >= 'A' && c <= 'Z')

            || (c >= '0' && c <= '9')

            || c == '_')

            continue;

        /* Dot and hyphen cannot be first or last. */

        if (i > 0 && i < utf8_length - 1) {

            if (c == '-')

                continue;

            /*

             * Next to a dot the preceding and following characters must not be

             * another dot or a hyphen.  Otherwise, record that the name is

             * plausible, since it has two or more labels.

             */

            if (c == '.'

                && utf8_value[i + 1] != '.'

                && utf8_value[i - 1] != '-'

                && utf8_value[i + 1] != '-') {

                isdnsname = 1;

                continue;

            }

        }

        isdnsname = 0;

        break;

    }

    if (isdnsname) {

        *dnsid = utf8_value;

        *idlen = (size_t)utf8_length;

        return X509_V_OK;

    }

    OPENSSL_free(utf8_value);

    return X509_V_OK;

}

/*

 * Check CN against DNS-ID name constraints.

 */

int NAME_CONSTRAINTS_check_CN(X509 *x, NAME_CONSTRAINTS *nc)

{

    int r, i;

    X509_NAME *nm = X509_get_subject_name(x);

    ASN1_STRING stmp;

    GENERAL_NAME gntmp;

    stmp.flags = 0;

    stmp.type = V_ASN1_IA5STRING;

    gntmp.type = GEN_DNS;

    gntmp.d.dNSName = &stmp;

    /* Process any commonName attributes in subject name */

    for (i = -1;;) {

        X509_NAME_ENTRY *ne;

        ASN1_STRING *cn;

        unsigned char *idval;

        size_t idlen;

        i = X509_NAME_get_index_by_NID(nm, NID_commonName, i);

        if (i == -1)

            break;

        ne = X509_NAME_get_entry(nm, i);

        cn = X509_NAME_ENTRY_get_data(ne);

        /* Only process attributes that look like host names */

        if ((r = cn2dnsid(cn, &idval, &idlen)) != X509_V_OK)

            return r;

        if (idlen == 0)

            continue;

        stmp.length = idlen;

        stmp.data = idval;

        r = nc_match(&gntmp, nc);

        OPENSSL_free(idval);

        if (r != X509_V_OK)

            return r;

    }

    return X509_V_OK;

}

static int nc_match(GENERAL_NAME *gen, NAME_CONSTRAINTS *nc)

{

    GENERAL_SUBTREE *sub;

    int i, r, match = 0;

    /*

     * Permitted subtrees: if any subtrees exist of matching the type at

     * least one subtree must match.

     */

    for (i = 0; i < sk_GENERAL_SUBTREE_num(nc->permittedSubtrees); i++) {

        sub = sk_GENERAL_SUBTREE_value(nc->permittedSubtrees, i);

        if (gen->type != sub->base->type)

            continue;

        if (sub->minimum || sub->maximum)

            return X509_V_ERR_SUBTREE_MINMAX;

        /* If we already have a match don't bother trying any more */

        if (match == 2)

            continue;

        if (match == 0)

            match = 1;

        r = nc_match_single(gen, sub->base);

        if (r == X509_V_OK)

            match = 2;

        else if (r != X509_V_ERR_PERMITTED_VIOLATION)

            return r;

    }

    if (match == 1)

        return X509_V_ERR_PERMITTED_VIOLATION;

    /* Excluded subtrees: must not match any of these */

    for (i = 0; i < sk_GENERAL_SUBTREE_num(nc->excludedSubtrees); i++) {

        sub = sk_GENERAL_SUBTREE_value(nc->excludedSubtrees, i);

        if (gen->type != sub->base->type)

            continue;

        if (sub->minimum || sub->maximum)

            return X509_V_ERR_SUBTREE_MINMAX;

        r = nc_match_single(gen, sub->base);

        if (r == X509_V_OK)

            return X509_V_ERR_EXCLUDED_VIOLATION;

        else if (r != X509_V_ERR_PERMITTED_VIOLATION)

            return r;

    }

    return X509_V_OK;

}

static int nc_match_single(GENERAL_NAME *gen, GENERAL_NAME *base)

{

    switch (base->type) {

    case GEN_DIRNAME:

        return nc_dn(gen->d.directoryName, base->d.directoryName);

    case GEN_DNS:

        return nc_dns(gen->d.dNSName, base->d.dNSName);

    case GEN_EMAIL:

        return nc_email(gen->d.rfc822Name, base->d.rfc822Name);

    case GEN_URI:

        return nc_uri(gen->d.uniformResourceIdentifier,

                      base->d.uniformResourceIdentifier);

    case GEN_IPADD:

        return nc_ip(gen->d.iPAddress, base->d.iPAddress);

    default:

        return X509_V_ERR_UNSUPPORTED_CONSTRAINT_TYPE;

    }

}

/*

 * directoryName name constraint matching. The canonical encoding of

 * X509_NAME makes this comparison easy. It is matched if the subtree is a

 * subset of the name.

 */

static int nc_dn(X509_NAME *nm, X509_NAME *base)

{

    /* Ensure canonical encodings are up to date.  */

    if (nm->modified && i2d_X509_NAME(nm, NULL) < 0)

        return X509_V_ERR_OUT_OF_MEM;

    if (base->modified && i2d_X509_NAME(base, NULL) < 0)

        return X509_V_ERR_OUT_OF_MEM;

    if (base->canon_enclen > nm->canon_enclen)

        return X509_V_ERR_PERMITTED_VIOLATION;

    if (memcmp(base->canon_enc, nm->canon_enc, base->canon_enclen))

        return X509_V_ERR_PERMITTED_VIOLATION;

    return X509_V_OK;

}

static int nc_dns(ASN1_IA5STRING *dns, ASN1_IA5STRING *base)

{

    char *baseptr = (char *)base->data;

    char *dnsptr = (char *)dns->data;

    /* Empty matches everything */

    if (base->length == 0)

        return X509_V_OK;

    if (dns->length < base->length)

        return X509_V_ERR_PERMITTED_VIOLATION;

    /*

     * Otherwise can add zero or more components on the left so compare RHS

     * and if dns is longer and expect '.' as preceding character.

     */

    if (dns->length > base->length) {

        dnsptr += dns->length - base->length;

        if (*baseptr != '.' && dnsptr[-1] != '.')

            return X509_V_ERR_PERMITTED_VIOLATION;

    }

    if (ia5ncasecmp(baseptr, dnsptr, base->length))

        return X509_V_ERR_PERMITTED_VIOLATION;

    return X509_V_OK;

}

static int nc_email(ASN1_IA5STRING *eml, ASN1_IA5STRING *base)

{

    const char *baseptr = (char *)base->data;

    const char *emlptr = (char *)eml->data;

    const char *baseat = ia5memrchr(base, '@');

    const char *emlat = ia5memrchr(eml, '@');

    size_t basehostlen, emlhostlen;

    if (!emlat)

        return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;

    /* Special case: initial '.' is RHS match */

    if (!baseat && base->length > 0 && (*baseptr == '.')) {

        if (eml->length > base->length) {

            emlptr += eml->length - base->length;

            if (ia5ncasecmp(baseptr, emlptr, base->length) == 0)

                return X509_V_OK;

        }

        return X509_V_ERR_PERMITTED_VIOLATION;

    }

    /* If we have anything before '@' match local part */

    if (baseat) {

        if (baseat != baseptr) {

            if ((baseat - baseptr) != (emlat - emlptr))

                return X509_V_ERR_PERMITTED_VIOLATION;

            /* Case sensitive match of local part */

            if (strncmp(baseptr, emlptr, emlat - emlptr))

                return X509_V_ERR_PERMITTED_VIOLATION;

        }

        /* Position base after '@' */

        baseptr = baseat + 1;

    }

    emlptr = emlat + 1;

    basehostlen = IA5_OFFSET_LEN(base, baseptr);

    emlhostlen = IA5_OFFSET_LEN(eml, emlptr);

    /* Just have hostname left to match: case insensitive */

    if (basehostlen != emlhostlen || ia5ncasecmp(baseptr, emlptr, emlhostlen))

        return X509_V_ERR_PERMITTED_VIOLATION;

    return X509_V_OK;

}

static int nc_uri(ASN1_IA5STRING *uri, ASN1_IA5STRING *base)

{

    const char *baseptr = (char *)base->data;

    const char *hostptr = (char *)uri->data;

    const char *p = ia5memchr(uri, (char *)uri->data, ':');

    int hostlen;

    /* Check for foo:// and skip past it */

    if (p == NULL

            || IA5_OFFSET_LEN(uri, p) < 3

            || p[1] != '/'

            || p[2] != '/')

        return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;

    hostptr = p + 3;

    /* Determine length of hostname part of URI */

    /* Look for a port indicator as end of hostname first */

    p = ia5memchr(uri, hostptr, ':');

    /* Otherwise look for trailing slash */

    if (p == NULL)

        p = ia5memchr(uri, hostptr, '/');

    if (p == NULL)

        hostlen = IA5_OFFSET_LEN(uri, hostptr);

    else

        hostlen = p - hostptr;

    if (hostlen == 0)

        return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;

    /* Special case: initial '.' is RHS match */

    if (base->length > 0 && *baseptr == '.') {

        if (hostlen > base->length) {

            p = hostptr + hostlen - base->length;

            if (ia5ncasecmp(p, baseptr, base->length) == 0)

                return X509_V_OK;

        }

        return X509_V_ERR_PERMITTED_VIOLATION;

    }

    if ((base->length != (int)hostlen)

        || ia5ncasecmp(hostptr, baseptr, hostlen))

        return X509_V_ERR_PERMITTED_VIOLATION;

    return X509_V_OK;

}

static int nc_ip(ASN1_OCTET_STRING *ip, ASN1_OCTET_STRING *base)

{

    int hostlen, baselen, i;

    unsigned char *hostptr, *baseptr, *maskptr;

    hostptr = ip->data;

    hostlen = ip->length;

    baseptr = base->data;

    baselen = base->length;

    /* Invalid if not IPv4 or IPv6 */

    if (!((hostlen == 4) || (hostlen == 16)))

        return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;

    if (!((baselen == 8) || (baselen == 32)))

        return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;

    /* Do not match IPv4 with IPv6 */

    if (hostlen * 2 != baselen)

        return X509_V_ERR_PERMITTED_VIOLATION;

    maskptr = base->data + hostlen;

    /* Considering possible not aligned base ipAddress */

    /* Not checking for wrong mask definition: i.e.: 255.0.255.0 */

    for (i = 0; i < hostlen; i++)

        if ((hostptr[i] & maskptr[i]) != (baseptr[i] & maskptr[i]))

            return X509_V_ERR_PERMITTED_VIOLATION;

    return X509_V_OK;

}