/*

 *  X.509 base functions for creating certificates / CSRs

 *

 *  Copyright The Mbed TLS Contributors

 *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later

 */

#include "common.h"

#if defined(MBEDTLS_X509_CREATE_C)

#include "x509_internal.h"

#include "mbedtls/asn1write.h"

#include "mbedtls/error.h"

#include "mbedtls/oid.h"

#include <string.h>

#include "mbedtls/platform.h"

#include "mbedtls/asn1.h"

/* Structure linking OIDs for X.509 DN AttributeTypes to their

 * string representations and default string encodings used by Mbed TLS. */

typedef struct {

    const char *name; /* String representation of AttributeType, e.g.

                       * "CN" or "emailAddress". */

    size_t name_len; /* Length of 'name', without trailing 0 byte. */

    const char *oid; /* String representation of OID of AttributeType,

                      * as per RFC 5280, Appendix A.1. encoded as per

                      * X.690 */

    int default_tag; /* The default character encoding used for the

                      * given attribute type, e.g.

                      * MBEDTLS_ASN1_UTF8_STRING for UTF-8. */

} x509_attr_descriptor_t;

#define ADD_STRLEN(s)     s, sizeof(s) - 1

/* X.509 DN attributes from RFC 5280, Appendix A.1. */

static const x509_attr_descriptor_t x509_attrs[] =

{

    { ADD_STRLEN("CN"),

      MBEDTLS_OID_AT_CN, MBEDTLS_ASN1_UTF8_STRING },

    { ADD_STRLEN("commonName"),

      MBEDTLS_OID_AT_CN, MBEDTLS_ASN1_UTF8_STRING },

    { ADD_STRLEN("C"),

      MBEDTLS_OID_AT_COUNTRY, MBEDTLS_ASN1_PRINTABLE_STRING },

    { ADD_STRLEN("countryName"),

      MBEDTLS_OID_AT_COUNTRY, MBEDTLS_ASN1_PRINTABLE_STRING },

    { ADD_STRLEN("O"),

      MBEDTLS_OID_AT_ORGANIZATION, MBEDTLS_ASN1_UTF8_STRING },

    { ADD_STRLEN("organizationName"),

      MBEDTLS_OID_AT_ORGANIZATION, MBEDTLS_ASN1_UTF8_STRING },

    { ADD_STRLEN("L"),

      MBEDTLS_OID_AT_LOCALITY, MBEDTLS_ASN1_UTF8_STRING },

    { ADD_STRLEN("locality"),

      MBEDTLS_OID_AT_LOCALITY, MBEDTLS_ASN1_UTF8_STRING },

    { ADD_STRLEN("R"),

      MBEDTLS_OID_PKCS9_EMAIL, MBEDTLS_ASN1_IA5_STRING },

    { ADD_STRLEN("OU"),

      MBEDTLS_OID_AT_ORG_UNIT, MBEDTLS_ASN1_UTF8_STRING },

    { ADD_STRLEN("organizationalUnitName"),

      MBEDTLS_OID_AT_ORG_UNIT, MBEDTLS_ASN1_UTF8_STRING },

    { ADD_STRLEN("ST"),

      MBEDTLS_OID_AT_STATE, MBEDTLS_ASN1_UTF8_STRING },

    { ADD_STRLEN("stateOrProvinceName"),

      MBEDTLS_OID_AT_STATE, MBEDTLS_ASN1_UTF8_STRING },

    { ADD_STRLEN("emailAddress"),

      MBEDTLS_OID_PKCS9_EMAIL, MBEDTLS_ASN1_IA5_STRING },

    { ADD_STRLEN("serialNumber"),

      MBEDTLS_OID_AT_SERIAL_NUMBER, MBEDTLS_ASN1_PRINTABLE_STRING },

    { ADD_STRLEN("postalAddress"),

      MBEDTLS_OID_AT_POSTAL_ADDRESS, MBEDTLS_ASN1_PRINTABLE_STRING },

    { ADD_STRLEN("postalCode"),

      MBEDTLS_OID_AT_POSTAL_CODE, MBEDTLS_ASN1_PRINTABLE_STRING },

    { ADD_STRLEN("dnQualifier"),

      MBEDTLS_OID_AT_DN_QUALIFIER, MBEDTLS_ASN1_PRINTABLE_STRING },

    { ADD_STRLEN("title"),

      MBEDTLS_OID_AT_TITLE, MBEDTLS_ASN1_UTF8_STRING },

    { ADD_STRLEN("surName"),

      MBEDTLS_OID_AT_SUR_NAME, MBEDTLS_ASN1_UTF8_STRING },

    { ADD_STRLEN("SN"),

      MBEDTLS_OID_AT_SUR_NAME, MBEDTLS_ASN1_UTF8_STRING },

    { ADD_STRLEN("givenName"),

      MBEDTLS_OID_AT_GIVEN_NAME, MBEDTLS_ASN1_UTF8_STRING },

    { ADD_STRLEN("GN"),

      MBEDTLS_OID_AT_GIVEN_NAME, MBEDTLS_ASN1_UTF8_STRING },

    { ADD_STRLEN("initials"),

      MBEDTLS_OID_AT_INITIALS, MBEDTLS_ASN1_UTF8_STRING },

    { ADD_STRLEN("pseudonym"),

      MBEDTLS_OID_AT_PSEUDONYM, MBEDTLS_ASN1_UTF8_STRING },

    { ADD_STRLEN("generationQualifier"),

      MBEDTLS_OID_AT_GENERATION_QUALIFIER, MBEDTLS_ASN1_UTF8_STRING },

    { ADD_STRLEN("domainComponent"),

      MBEDTLS_OID_DOMAIN_COMPONENT, MBEDTLS_ASN1_IA5_STRING },

    { ADD_STRLEN("DC"),

      MBEDTLS_OID_DOMAIN_COMPONENT,   MBEDTLS_ASN1_IA5_STRING },

    { NULL, 0, NULL, MBEDTLS_ASN1_NULL }

};

static const x509_attr_descriptor_t *x509_attr_descr_from_name(const char *name, size_t name_len)

{

    const x509_attr_descriptor_t *cur;

    for (cur = x509_attrs; cur->name != NULL; cur++) {

        if (cur->name_len == name_len &&

            strncmp(cur->name, name, name_len) == 0) {

            break;

        }

    }

    if (cur->name == NULL) {

        return NULL;

    }

    return cur;

}

static int hex_to_int(char c)

{

    return ('0' <= c && c <= '9') ? (c - '0') :

           ('a' <= c && c <= 'f') ? (c - 'a' + 10) :

           ('A' <= c && c <= 'F') ? (c - 'A' + 10) : -1;

}

static int hexpair_to_int(const char *hexpair)

{

    int n1 = hex_to_int(*hexpair);

    int n2 = hex_to_int(*(hexpair + 1));

    if (n1 != -1 && n2 != -1) {

        return (n1 << 4) | n2;

    } else {

        return -1;

    }

}

static int parse_attribute_value_string(const char *s,

                                        int len,

                                        unsigned char *data,

                                        size_t *data_len)

{

    const char *c;

    const char *end = s + len;

    unsigned char *d = data;

    int n;

    for (c = s; c < end; c++) {

        if (*c == '\\') {

            c++;

            /* Check for valid escaped characters as per RFC 4514 Section 3 */

            if (c + 1 < end && (n = hexpair_to_int(c)) != -1) {

                if (n == 0) {

                    return MBEDTLS_ERR_X509_INVALID_NAME;

                }

                *(d++) = n;

                c++;

            } else if (c < end && strchr(" ,=+<>#;\"\\", *c)) {

                *(d++) = *c;

            } else {

                return MBEDTLS_ERR_X509_INVALID_NAME;

            }

        } else {

            *(d++) = *c;

        }

        if (d - data == MBEDTLS_X509_MAX_DN_NAME_SIZE) {

            return MBEDTLS_ERR_X509_INVALID_NAME;

        }

    }

    *data_len = (size_t) (d - data);

    return 0;

}

/** Parse a hexstring containing a DER-encoded string.

 *

 * \param s         A string of \p len bytes hexadecimal digits.

 * \param len       Number of bytes to read from \p s.

 * \param data      Output buffer of size \p data_size.

 *                  On success, it contains the payload that's DER-encoded

 *                  in the input (content without the tag and length).

 *                  If the DER tag is a string tag, the payload is guaranteed

 *                  not to contain null bytes.

 * \param data_size Length of the \p data buffer.

 * \param data_len  On success, the length of the parsed string.

 *                  It is guaranteed to be less than

 *                  #MBEDTLS_X509_MAX_DN_NAME_SIZE.

 * \param tag       The ASN.1 tag that the payload in \p data is encoded in.

 *

 * \retval          0 on success.

 * \retval          #MBEDTLS_ERR_X509_INVALID_NAME if \p s does not contain

 *                  a valid hexstring,

 *                  or if the decoded hexstring is not valid DER,

 *                  or if the payload does not fit in \p data,

 *                  or if the payload is more than

 *                  #MBEDTLS_X509_MAX_DN_NAME_SIZE bytes,

 *                  of if \p *tag is an ASN.1 string tag and the payload

 *                  contains a null byte.

 * \retval          #MBEDTLS_ERR_X509_ALLOC_FAILED on low memory.

 */

static int parse_attribute_value_hex_der_encoded(const char *s,

                                                 size_t len,

                                                 unsigned char *data,

                                                 size_t data_size,

                                                 size_t *data_len,

                                                 int *tag)

{

    /* Step 1: preliminary length checks. */

    /* Each byte is encoded by exactly two hexadecimal digits. */

    if (len % 2 != 0) {

        /* Odd number of hex digits */

        return MBEDTLS_ERR_X509_INVALID_NAME;

    }

    size_t const der_length = len / 2;

    if (der_length > MBEDTLS_X509_MAX_DN_NAME_SIZE + 4) {

        /* The payload would be more than MBEDTLS_X509_MAX_DN_NAME_SIZE

         * (after subtracting the ASN.1 tag and length). Reject this early

         * to avoid allocating a large intermediate buffer. */

        return MBEDTLS_ERR_X509_INVALID_NAME;

    }

    if (der_length < 1) {

        /* Avoid empty-buffer shenanigans. A valid DER encoding is never

         * empty. */

        return MBEDTLS_ERR_X509_INVALID_NAME;

    }

    /* Step 2: Decode the hex string into an intermediate buffer. */

    unsigned char *der = mbedtls_calloc(1, der_length);

    if (der == NULL) {

        return MBEDTLS_ERR_X509_ALLOC_FAILED;

    }

    /* Beyond this point, der needs to be freed on exit. */

    for (size_t i = 0; i < der_length; i++) {

        int c = hexpair_to_int(s + 2 * i);

        if (c < 0) {

            goto error;

        }

        der[i] = c;

    }

    /* Step 3: decode the DER. */

    /* We've checked that der_length >= 1 above. */

    *tag = der[0];

    {

        unsigned char *p = der + 1;

        if (mbedtls_asn1_get_len(&p, der + der_length, data_len) != 0) {

            goto error;

        }

        /* Now p points to the first byte of the payload inside der,

         * and *data_len is the length of the payload. */

        /* Step 4: payload validation */

        if (*data_len > MBEDTLS_X509_MAX_DN_NAME_SIZE) {

            goto error;

        }

        /* Strings must not contain null bytes. */

        if (MBEDTLS_ASN1_IS_STRING_TAG(*tag)) {

            for (size_t i = 0; i < *data_len; i++) {

                if (p[i] == 0) {

                    goto error;

                }

            }

        }

        /* Step 5: output the payload. */

        if (*data_len > data_size) {

            goto error;

        }

        memcpy(data, p, *data_len);

    }

    mbedtls_free(der);

    return 0;

error:

    mbedtls_free(der);

    return MBEDTLS_ERR_X509_INVALID_NAME;

}

int mbedtls_x509_string_to_names(mbedtls_asn1_named_data **head, const char *name)

{

    int ret = MBEDTLS_ERR_X509_INVALID_NAME;

    int parse_ret = 0;

    const char *s = name, *c = s;

    const char *end = s + strlen(s);

    mbedtls_asn1_buf oid = { .p = NULL, .len = 0, .tag = MBEDTLS_ASN1_NULL };

    const x509_attr_descriptor_t *attr_descr = NULL;

    int in_attr_type = 1;

    int tag;

    int numericoid = 0;

    unsigned char data[MBEDTLS_X509_MAX_DN_NAME_SIZE];

    size_t data_len = 0;

    /* Ensure the output parameter is not already populated.

     * (If it were, overwriting it would likely cause a memory leak.)

     */

    if (*head != NULL) {

        return MBEDTLS_ERR_X509_BAD_INPUT_DATA;

    }

    while (c <= end) {

        if (in_attr_type && *c == '=') {

            if ((attr_descr = x509_attr_descr_from_name(s, (size_t) (c - s))) == NULL) {

                if ((mbedtls_oid_from_numeric_string(&oid, s, (size_t) (c - s))) != 0) {

                    return MBEDTLS_ERR_X509_INVALID_NAME;

                } else {

                    numericoid = 1;

                }

            } else {

                oid.len = strlen(attr_descr->oid);

                oid.p = mbedtls_calloc(1, oid.len);

                if (oid.p == NULL) {

                    return MBEDTLS_ERR_X509_ALLOC_FAILED;

                }

                memcpy(oid.p, attr_descr->oid, oid.len);

                numericoid = 0;

            }

            s = c + 1;

            in_attr_type = 0;

        }

        if (!in_attr_type && ((*c == ',' && *(c-1) != '\\') || c == end)) {

            if (s == c) {

                mbedtls_free(oid.p);

                return MBEDTLS_ERR_X509_INVALID_NAME;

            } else if (*s == '#') {

                /* We know that c >= s (loop invariant) and c != s (in this

                 * else branch), hence c - s - 1 >= 0. */

                parse_ret = parse_attribute_value_hex_der_encoded(

                    s + 1, (size_t) (c - s) - 1,

                    data, sizeof(data), &data_len, &tag);

                if (parse_ret != 0) {

                    mbedtls_free(oid.p);

                    return parse_ret;

                }

            } else {

                if (numericoid) {

                    mbedtls_free(oid.p);

                    return MBEDTLS_ERR_X509_INVALID_NAME;

                } else {

                    if ((parse_ret =

                             parse_attribute_value_string(s, (int) (c - s), data,

                                                          &data_len)) != 0) {

                        mbedtls_free(oid.p);

                        return parse_ret;

                    }

                    tag = attr_descr->default_tag;

                }

            }

            mbedtls_asn1_named_data *cur =

                mbedtls_asn1_store_named_data(head, (char *) oid.p, oid.len,

                                              (unsigned char *) data,

                                              data_len);

            mbedtls_free(oid.p);

            oid.p = NULL;

            if (cur == NULL) {

                return MBEDTLS_ERR_X509_ALLOC_FAILED;

            }

            // set tagType

            cur->val.tag = tag;

            while (c < end && *(c + 1) == ' ') {

                c++;

            }

            s = c + 1;

            in_attr_type = 1;

            /* Successfully parsed one name, update ret to success */

            ret = 0;

        }

        c++;

    }

    if (oid.p != NULL) {

        mbedtls_free(oid.p);

    }

    return ret;

}

/* The first byte of the value in the mbedtls_asn1_named_data structure is reserved

 * to store the critical boolean for us

 */

int mbedtls_x509_set_extension(mbedtls_asn1_named_data **head, const char *oid, size_t oid_len,

                               int critical, const unsigned char *val, size_t val_len)

{

    mbedtls_asn1_named_data *cur;

    if (val_len > (SIZE_MAX  - 1)) {

        return MBEDTLS_ERR_X509_BAD_INPUT_DATA;

    }

    if ((cur = mbedtls_asn1_store_named_data(head, oid, oid_len,

                                             NULL, val_len + 1)) == NULL) {

        return MBEDTLS_ERR_X509_ALLOC_FAILED;

    }

    cur->val.p[0] = critical;

    memcpy(cur->val.p + 1, val, val_len);

    return 0;

}

/*

 *  RelativeDistinguishedName ::=

 *    SET OF AttributeTypeAndValue

 *

 *  AttributeTypeAndValue ::= SEQUENCE {

 *    type     AttributeType,

 *    value    AttributeValue }

 *

 *  AttributeType ::= OBJECT IDENTIFIER

 *

 *  AttributeValue ::= ANY DEFINED BY AttributeType

 */

static int x509_write_name(unsigned char **p,

                           unsigned char *start,

                           mbedtls_asn1_named_data *cur_name)

{

    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

    size_t len = 0;

    const char *oid             = (const char *) cur_name->oid.p;

    size_t oid_len              = cur_name->oid.len;

    const unsigned char *name   = cur_name->val.p;

    size_t name_len             = cur_name->val.len;

    // Write correct string tag and value

    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tagged_string(p, start,

                                                               cur_name->val.tag,

                                                               (const char *) name,

                                                               name_len));

    // Write OID

    //

    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_oid(p, start, oid,

                                                     oid_len));

    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));

    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start,

                                                     MBEDTLS_ASN1_CONSTRUCTED |

                                                     MBEDTLS_ASN1_SEQUENCE));

    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));

    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start,

                                                     MBEDTLS_ASN1_CONSTRUCTED |

                                                     MBEDTLS_ASN1_SET));

    return (int) len;

}

int mbedtls_x509_write_names(unsigned char **p, unsigned char *start,

                             mbedtls_asn1_named_data *first)

{

    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

    size_t len = 0;

    mbedtls_asn1_named_data *cur = first;

    while (cur != NULL) {

        MBEDTLS_ASN1_CHK_ADD(len, x509_write_name(p, start, cur));

        cur = cur->next;

    }

    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));

    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, MBEDTLS_ASN1_CONSTRUCTED |

                                                     MBEDTLS_ASN1_SEQUENCE));

    return (int) len;

}

int mbedtls_x509_write_sig(unsigned char **p, unsigned char *start,

                           const char *oid, size_t oid_len,

                           unsigned char *sig, size_t size,

                           mbedtls_pk_type_t pk_alg)

{

    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

    int write_null_par;

    size_t len = 0;

    if (*p < start || (size_t) (*p - start) < size) {

        return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;

    }

    len = size;

    (*p) -= len;

    memcpy(*p, sig, len);

    if (*p - start < 1) {

        return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;

    }

    *--(*p) = 0;

    len += 1;

    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));

    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, MBEDTLS_ASN1_BIT_STRING));

    // Write OID

    //

    if (pk_alg == MBEDTLS_PK_ECDSA) {

        /*

         * The AlgorithmIdentifier's parameters field must be absent for DSA/ECDSA signature

         * algorithms, see https://www.rfc-editor.org/rfc/rfc5480#page-17 and

         * https://www.rfc-editor.org/rfc/rfc5758#section-3.

         */

        write_null_par = 0;

    } else {

        write_null_par = 1;

    }

    MBEDTLS_ASN1_CHK_ADD(len,

                         mbedtls_asn1_write_algorithm_identifier_ext(p, start, oid, oid_len,

                                                                     0, write_null_par));

    return (int) len;

}

static int x509_write_extension(unsigned char **p, unsigned char *start,

                                mbedtls_asn1_named_data *ext)

{

    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

    size_t len = 0;

    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_raw_buffer(p, start, ext->val.p + 1,

                                                            ext->val.len - 1));

    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, ext->val.len - 1));

    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, MBEDTLS_ASN1_OCTET_STRING));

    if (ext->val.p[0] != 0) {

        MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_bool(p, start, 1));

    }

    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_raw_buffer(p, start, ext->oid.p,

                                                            ext->oid.len));

    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, ext->oid.len));

    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, MBEDTLS_ASN1_OID));

    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(p, start, len));

    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(p, start, MBEDTLS_ASN1_CONSTRUCTED |

                                                     MBEDTLS_ASN1_SEQUENCE));

    return (int) len;

}

/*

 * Extension  ::=  SEQUENCE  {

 *     extnID      OBJECT IDENTIFIER,

 *     critical    BOOLEAN DEFAULT FALSE,

 *     extnValue   OCTET STRING

 *                 -- contains the DER encoding of an ASN.1 value

 *                 -- corresponding to the extension type identified

 *                 -- by extnID

 *     }

 */

int mbedtls_x509_write_extensions(unsigned char **p, unsigned char *start,

                                  mbedtls_asn1_named_data *first)

{

    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

    size_t len = 0;

    mbedtls_asn1_named_data *cur_ext = first;

    while (cur_ext != NULL) {

        MBEDTLS_ASN1_CHK_ADD(len, x509_write_extension(p, start, cur_ext));

        cur_ext = cur_ext->next;

    }

    return (int) len;

}

#endif /* MBEDTLS_X509_CREATE_C */