path: root/openssl/crypto/x509v3/v3_utl.c

/* v3_utl.c */
/*
 * 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).
 *
 */
/* X509 v3 extension utilities */

#include <stdio.h>
#include <ctype.h>
#include "cryptlib.h"
#include <openssl/conf.h>
#include <openssl/x509v3.h>
#include <openssl/bn.h>

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;
    char *tname = NULL, *tvalue = NULL;
    if (name && !(tname = BUF_strdup(name)))
        goto err;
    if (value && !(tvalue = BUF_strdup(value)))
        goto err;
    if (!(vtmp = (CONF_VALUE *)OPENSSL_malloc(sizeof(CONF_VALUE))))
        goto err;
    if (!*extlist && !(*extlist = sk_CONF_VALUE_new_null()))
        goto err;
    vtmp->section = NULL;
    vtmp->name = tname;
    vtmp->value = tvalue;
    if (!sk_CONF_VALUE_push(*extlist, vtmp))
        goto err;
    return 1;
 err:
    X509V3err(X509V3_F_X509V3_ADD_VALUE, ERR_R_MALLOC_FAILURE);
    if (vtmp)
        OPENSSL_free(vtmp);
    if (tname)
        OPENSSL_free(tname);
    if (tvalue)
        OPENSSL_free(tvalue);
    return 0;
}

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);
}

/* Free function for STACK_OF(CONF_VALUE) */

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

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);
}

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

char *i2s_ASN1_ENUMERATED(X509V3_EXT_METHOD *method, ASN1_ENUMERATED *a)
{
    BIGNUM *bntmp = NULL;
    char *strtmp = NULL;
    if (!a)
        return NULL;
    if (!(bntmp = ASN1_ENUMERATED_to_BN(a, NULL)) ||
        !(strtmp = BN_bn2dec(bntmp)))
        X509V3err(X509V3_F_I2S_ASN1_ENUMERATED, ERR_R_MALLOC_FAILURE);
    BN_free(bntmp);
    return strtmp;
}

char *i2s_ASN1_INTEGER(X509V3_EXT_METHOD *method, ASN1_INTEGER *a)
{
    BIGNUM *bntmp = NULL;
    char *strtmp = NULL;
    if (!a)
        return NULL;
    if (!(bntmp = ASN1_INTEGER_to_BN(a, NULL)) ||
        !(strtmp = BN_bn2dec(bntmp)))
        X509V3err(X509V3_F_I2S_ASN1_INTEGER, ERR_R_MALLOC_FAILURE);
    BN_free(bntmp);
    return strtmp;
}

ASN1_INTEGER *s2i_ASN1_INTEGER(X509V3_EXT_METHOD *method, char *value)
{
    BIGNUM *bn = NULL;
    ASN1_INTEGER *aint;
    int isneg, ishex;
    int ret;
    if (!value) {
        X509V3err(X509V3_F_S2I_ASN1_INTEGER, X509V3_R_INVALID_NULL_VALUE);
        return 0;
    }
    bn = BN_new();
    if (value[0] == '-') {
        value++;
        isneg = 1;
    } else
        isneg = 0;

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

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

    if (!ret || value[ret]) {
        BN_free(bn);
        X509V3err(X509V3_F_S2I_ASN1_INTEGER, X509V3_R_BN_DEC2BN_ERROR);
        return 0;
    }

    if (isneg && BN_is_zero(bn))
        isneg = 0;

    aint = BN_to_ASN1_INTEGER(bn, NULL);
    BN_free(bn);
    if (!aint) {
        X509V3err(X509V3_F_S2I_ASN1_INTEGER,
                  X509V3_R_BN_TO_ASN1_INTEGER_ERROR);
        return 0;
    }
    if (isneg)
        aint->type |= V_ASN1_NEG;
    return aint;
}

int X509V3_add_value_int(const char *name, 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);
    OPENSSL_free(strtmp);
    return ret;
}

int X509V3_get_value_bool(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:
    X509V3err(X509V3_F_X509V3_GET_VALUE_BOOL,
              X509V3_R_INVALID_BOOLEAN_STRING);
    X509V3_conf_err(value);
    return 0;
}

int X509V3_get_value_int(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

/*
 * #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 */
    linebuf = BUF_strdup(line);
    if (linebuf == NULL) {
        X509V3err(X509V3_F_X509V3_PARSE_LIST, 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) {
                    X509V3err(X509V3_F_X509V3_PARSE_LIST,
                              X509V3_R_INVALID_NULL_NAME);
                    goto err;
                }
                q = p + 1;
            } else if (c == ',') {
                *p = 0;
                ntmp = strip_spaces(q);
                q = p + 1;
#if 0
                printf("%s\n", ntmp);
#endif
                if (!ntmp) {
                    X509V3err(X509V3_F_X509V3_PARSE_LIST,
                              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 0
                printf("%s\n", ntmp);
#endif
                if (!vtmp) {
                    X509V3err(X509V3_F_X509V3_PARSE_LIST,
                              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 0
        printf("%s=%s\n", ntmp, vtmp);
#endif
        if (!vtmp) {
            X509V3err(X509V3_F_X509V3_PARSE_LIST,
                      X509V3_R_INVALID_NULL_VALUE);
            goto err;
        }
        X509V3_add_value(ntmp, vtmp, &values);
    } else {
        ntmp = strip_spaces(q);
#if 0
        printf("%s\n", ntmp);
#endif
        if (!ntmp) {
            X509V3err(X509V3_F_X509V3_PARSE_LIST, X509V3_R_INVALID_NULL_NAME);
            goto err;
        }
        X509V3_add_value(ntmp, NULL, &values);
    }
    OPENSSL_free(linebuf);
    return values;

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

}

/* 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;
}

/* hex string utilities */

/*
 * Given a buffer of length 'len' return a OPENSSL_malloc'ed string with its
 * hex representation @@@ (Contents of buffer are always kept in ASCII, also
 * on EBCDIC machines)
 */

char *hex_to_string(const unsigned char *buffer, long len)
{
    char *tmp, *q;
    const unsigned char *p;
    int i;
    const static char hexdig[] = "0123456789ABCDEF";
    if (!buffer || !len)
        return NULL;
    if (!(tmp = OPENSSL_malloc(len * 3 + 1))) {
        X509V3err(X509V3_F_HEX_TO_STRING, ERR_R_MALLOC_FAILURE);
        return NULL;
    }
    q = tmp;
    for (i = 0, p = buffer; i < len; i++, p++) {
        *q++ = hexdig[(*p >> 4) & 0xf];
        *q++ = hexdig[*p & 0xf];
        *q++ = ':';
    }
    q[-1] = 0;
#ifdef CHARSET_EBCDIC
    ebcdic2ascii(tmp, tmp, q - tmp - 1);
#endif

    return tmp;
}

/*
 * Give a string of hex digits convert to a buffer
 */

unsigned char *string_to_hex(const char *str, long *len)
{
    unsigned char *hexbuf, *q;
    unsigned char ch, cl, *p;
    if (!str) {
        X509V3err(X509V3_F_STRING_TO_HEX, X509V3_R_INVALID_NULL_ARGUMENT);
        return NULL;
    }
    if (!(hexbuf = OPENSSL_malloc(strlen(str) >> 1)))
        goto err;
    for (p = (unsigned char *)str, q = hexbuf; *p;) {
        ch = *p++;
#ifdef CHARSET_EBCDIC
        ch = os_toebcdic[ch];
#endif
        if (ch == ':')
            continue;
        cl = *p++;
#ifdef CHARSET_EBCDIC
        cl = os_toebcdic[cl];
#endif
        if (!cl) {
            X509V3err(X509V3_F_STRING_TO_HEX, X509V3_R_ODD_NUMBER_OF_DIGITS);
            OPENSSL_free(hexbuf);
            return NULL;
        }
        if (isupper(ch))
            ch = tolower(ch);
        if (isupper(cl))
            cl = tolower(cl);

        if ((ch >= '0') && (ch <= '9'))
            ch -= '0';
        else if ((ch >= 'a') && (ch <= 'f'))
            ch -= 'a' - 10;
        else
            goto badhex;

        if ((cl >= '0') && (cl <= '9'))
            cl -= '0';
        else if ((cl >= 'a') && (cl <= 'f'))
            cl -= 'a' - 10;
        else
            goto badhex;

        *q++ = (ch << 4) | cl;
    }

    if (len)
        *len = q - hexbuf;

    return hexbuf;

 err:
    if (hexbuf)
        OPENSSL_free(hexbuf);
    X509V3err(X509V3_F_STRING_TO_HEX, ERR_R_MALLOC_FAILURE);
    return NULL;

 badhex:
    OPENSSL_free(hexbuf);
    X509V3err(X509V3_F_STRING_TO_HEX, X509V3_R_ILLEGAL_HEX_DIGIT);
    return NULL;

}

/*
 * 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;
}

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;
}

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;
}

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)
{
    OPENSSL_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 = BUF_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);
}

/*
 * 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;
}

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 = BUF_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);

    OPENSSL_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:
    if (iptmp)
        OPENSSL_free(iptmp);
    if (ret)
        ASN1_OCTET_STRING_free(ret);
    return NULL;
}

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;
    }
}

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, two or three 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++)
#ifndef CHARSET_EBCDIC
            if ((*p == ':') || (*p == ',') || (*p == '.'))
#else
            if ((*p == os_toascii[':']) || (*p == os_toascii[','])
                || (*p == os_toascii['.']))
#endif
            {
                p++;
                if (*p)
                    type = p;
                break;
            }
#ifndef CHARSET_EBCDIC
        if (*type == '+')
#else
        if (*type == os_toascii['+'])
#endif
        {
            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;
}