/*

 * Copyright 2000-2026 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the Apache License 2.0 (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 <stddef.h>

#include <string.h>

#include "internal/cryptlib.h"

#include <openssl/asn1.h>

#include <openssl/asn1t.h>

#include <openssl/objects.h>

#include "crypto/asn1.h"

#include "asn1_local.h"

static int asn1_i2d_ex_primitive(const ASN1_VALUE **pval, unsigned char **out,

    const ASN1_ITEM *it, int tag, int aclass);

static int asn1_set_seq_out(STACK_OF(const_ASN1_VALUE) *sk,

    unsigned char **out,

    int skcontlen, const ASN1_ITEM *item,

    int do_sort, int iclass);

static int asn1_template_ex_i2d(const ASN1_VALUE **pval, unsigned char **out,

    const ASN1_TEMPLATE *tt, int tag, int aclass);

static int asn1_item_flags_i2d(const ASN1_VALUE *val, unsigned char **out,

    const ASN1_ITEM *it, int flags);

static int asn1_ex_i2c(const ASN1_VALUE **pval, unsigned char *cout, int *putype,

    const ASN1_ITEM *it);

/*

 * Top level i2d equivalents: the 'ndef' variant instructs the encoder to use

 * indefinite length constructed encoding, where appropriate

 */

int ASN1_item_ndef_i2d(const ASN1_VALUE *val, unsigned char **out,

    const ASN1_ITEM *it)

{

    return asn1_item_flags_i2d(val, out, it, ASN1_TFLG_NDEF);

}

int ASN1_item_i2d(const ASN1_VALUE *val, unsigned char **out, const ASN1_ITEM *it)

{

    return asn1_item_flags_i2d(val, out, it, 0);

}

/*

 * Encode an ASN1 item, this is use by the standard 'i2d' function. 'out'

 * points to a buffer to output the data to. The new i2d has one additional

 * feature. If the output buffer is NULL (i.e. *out == NULL) then a buffer is

 * allocated and populated with the encoding.

 */

static int asn1_item_flags_i2d(const ASN1_VALUE *val, unsigned char **out,

    const ASN1_ITEM *it, int flags)

{

    if (out != NULL && *out == NULL) {

        unsigned char *p, *buf;

        int len;

        len = ASN1_item_ex_i2d(&val, NULL, it, -1, flags);

        if (len <= 0)

            return len;

        if ((buf = OPENSSL_malloc(len)) == NULL)

            return -1;

        p = buf;

        ASN1_item_ex_i2d(&val, &p, it, -1, flags);

        *out = buf;

        return len;

    }

    return ASN1_item_ex_i2d(&val, out, it, -1, flags);

}

/*

 * Encode an item, taking care of IMPLICIT tagging (if any). This function

 * performs the normal item handling: it can be used in external types.

 */

int ASN1_item_ex_i2d(const ASN1_VALUE **pval, unsigned char **out,

    const ASN1_ITEM *it, int tag, int aclass)

{

    const ASN1_TEMPLATE *tt = NULL;

    int i, seqcontlen, seqlen, ndef = 1;

    const ASN1_EXTERN_FUNCS *ef;

    const ASN1_AUX *aux = it->funcs;

    ASN1_aux_const_cb *asn1_cb = NULL;

    if ((it->itype != ASN1_ITYPE_PRIMITIVE) && *pval == NULL)

        return 0;

    if (aux != NULL) {

        asn1_cb = ((aux->flags & ASN1_AFLG_CONST_CB) != 0) ? aux->asn1_const_cb

                                                           : (ASN1_aux_const_cb *)aux->asn1_cb; /* backward compatibility */

    }

    switch (it->itype) {

    case ASN1_ITYPE_PRIMITIVE:

        if (it->templates)

            return asn1_template_ex_i2d(pval, out, it->templates,

                tag, aclass);

        return asn1_i2d_ex_primitive(pval, out, it, tag, aclass);

    case ASN1_ITYPE_MSTRING:

        /*

         * It never makes sense for multi-strings to have implicit tagging, so

         * if tag != -1, then this looks like an error in the template.

         */

        if (tag != -1) {

            ERR_raise(ERR_LIB_ASN1, ASN1_R_BAD_TEMPLATE);

            return -1;

        }

        return asn1_i2d_ex_primitive(pval, out, it, -1, aclass);

    case ASN1_ITYPE_CHOICE:

        /*

         * It never makes sense for CHOICE types to have implicit tagging, so

         * if tag != -1, then this looks like an error in the template.

         */

        if (tag != -1) {

            ERR_raise(ERR_LIB_ASN1, ASN1_R_BAD_TEMPLATE);

            return -1;

        }

        if (asn1_cb && !asn1_cb(ASN1_OP_I2D_PRE, pval, it, NULL))

            return 0;

        i = ossl_asn1_get_choice_selector_const(pval, it);

        if ((i >= 0) && (i < it->tcount)) {

            const ASN1_VALUE **pchval;

            const ASN1_TEMPLATE *chtt;

            chtt = it->templates + i;

            pchval = ossl_asn1_get_const_field_ptr(pval, chtt);

            return asn1_template_ex_i2d(pchval, out, chtt, -1, aclass);

        }

        /* Fixme: error condition if selector out of range */

        if (asn1_cb && !asn1_cb(ASN1_OP_I2D_POST, pval, it, NULL))

            return 0;

        break;

    case ASN1_ITYPE_EXTERN:

        /* If new style i2d it does all the work */

        ef = it->funcs;

        return ef->asn1_ex_i2d(pval, out, it, tag, aclass);

    case ASN1_ITYPE_NDEF_SEQUENCE:

        /* Use indefinite length constructed if requested */

        if (aclass & ASN1_TFLG_NDEF)

            ndef = 2;

        /* fall through */

    case ASN1_ITYPE_SEQUENCE:

        i = ossl_asn1_enc_restore(&seqcontlen, out, pval, it);

        /* An error occurred */

        if (i < 0)

            return 0;

        /* We have a valid cached encoding... */

        if (i > 0)

            return seqcontlen;

        /* Otherwise carry on */

        seqcontlen = 0;

        /* If no IMPLICIT tagging set to SEQUENCE, UNIVERSAL */

        if (tag == -1) {

            tag = V_ASN1_SEQUENCE;

            /* Retain any other flags in aclass */

            aclass = (aclass & ~ASN1_TFLG_TAG_CLASS)

                | V_ASN1_UNIVERSAL;

        }

        if (asn1_cb && !asn1_cb(ASN1_OP_I2D_PRE, pval, it, NULL))

            return 0;

        /* First work out sequence content length */

        for (i = 0, tt = it->templates; i < it->tcount; tt++, i++) {

            const ASN1_TEMPLATE *seqtt;

            const ASN1_VALUE **pseqval;

            int tmplen;

            seqtt = ossl_asn1_do_adb(*pval, tt, 1);

            if (!seqtt)

                return 0;

            pseqval = ossl_asn1_get_const_field_ptr(pval, seqtt);

            tmplen = asn1_template_ex_i2d(pseqval, NULL, seqtt, -1, aclass);

            if (tmplen == -1 || (tmplen > INT_MAX - seqcontlen))

                return -1;

            seqcontlen += tmplen;

        }

        seqlen = ASN1_object_size(ndef, seqcontlen, tag);

        if (!out || seqlen == -1)

            return seqlen;

        /* Output SEQUENCE header */

        ASN1_put_object(out, ndef, seqcontlen, tag, aclass);

        for (i = 0, tt = it->templates; i < it->tcount; tt++, i++) {

            const ASN1_TEMPLATE *seqtt;

            const ASN1_VALUE **pseqval;

            seqtt = ossl_asn1_do_adb(*pval, tt, 1);

            if (!seqtt)

                return 0;

            pseqval = ossl_asn1_get_const_field_ptr(pval, seqtt);

            /* FIXME: check for errors in enhanced version */

            asn1_template_ex_i2d(pseqval, out, seqtt, -1, aclass);

        }

        if (ndef == 2)

            ASN1_put_eoc(out);

        if (asn1_cb && !asn1_cb(ASN1_OP_I2D_POST, pval, it, NULL))

            return 0;

        return seqlen;

    default:

        return 0;

    }

    return 0;

}

static int asn1_template_ex_i2d(const ASN1_VALUE **pval, unsigned char **out,

    const ASN1_TEMPLATE *tt, int tag, int iclass)

{

    const int flags = tt->flags;

    int i, ret, ttag, tclass, ndef, len;

    const ASN1_VALUE *tval;

    /*

     * If field is embedded then val needs fixing so it is a pointer to

     * a pointer to a field.

     */

    if (flags & ASN1_TFLG_EMBED) {

        tval = (ASN1_VALUE *)pval;

        pval = &tval;

    }

    /*

     * Work out tag and class to use: tagging may come either from the

     * template or the arguments, not both because this would create

     * ambiguity. Additionally the iclass argument may contain some

     * additional flags which should be noted and passed down to other

     * levels.

     */

    if (flags & ASN1_TFLG_TAG_MASK) {

        /* Error if argument and template tagging */

        if (tag != -1)

            /* FIXME: error code here */

            return -1;

        /* Get tagging from template */

        ttag = tt->tag;

        tclass = flags & ASN1_TFLG_TAG_CLASS;

    } else if (tag != -1) {

        /* No template tagging, get from arguments */

        ttag = tag;

        tclass = iclass & ASN1_TFLG_TAG_CLASS;

    } else {

        ttag = -1;

        tclass = 0;

    }

    /*

     * Remove any class mask from iflag.

     */

    iclass &= ~ASN1_TFLG_TAG_CLASS;

    /*

     * At this point 'ttag' contains the outer tag to use, 'tclass' is the

     * class and iclass is any flags passed to this function.

     */

    /* if template and arguments require ndef, use it */

    if ((flags & ASN1_TFLG_NDEF) && (iclass & ASN1_TFLG_NDEF))

        ndef = 2;

    else

        ndef = 1;

    if (flags & ASN1_TFLG_SK_MASK) {

        /* SET OF, SEQUENCE OF */

        STACK_OF(const_ASN1_VALUE) *sk = (STACK_OF(const_ASN1_VALUE) *)*pval;

        int isset, sktag, skaclass;

        int skcontlen, sklen;

        const ASN1_VALUE *skitem;

        if (*pval == NULL)

            return 0;

        if (flags & ASN1_TFLG_SET_OF) {

            isset = 1;

            /* 2 means we reorder */

            if (flags & ASN1_TFLG_SEQUENCE_OF)

                isset = 2;

        } else

            isset = 0;

        /*

         * Work out inner tag value: if EXPLICIT or no tagging use underlying

         * type.

         */

        if ((ttag != -1) && !(flags & ASN1_TFLG_EXPTAG)) {

            sktag = ttag;

            skaclass = tclass;

        } else {

            skaclass = V_ASN1_UNIVERSAL;

            if (isset)

                sktag = V_ASN1_SET;

            else

                sktag = V_ASN1_SEQUENCE;

        }

        /* Determine total length of items */

        skcontlen = 0;

        for (i = 0; i < sk_const_ASN1_VALUE_num(sk); i++) {

            skitem = sk_const_ASN1_VALUE_value(sk, i);

            len = ASN1_item_ex_i2d(&skitem, NULL, ASN1_ITEM_ptr(tt->item),

                -1, iclass);

            if (len == -1 || (skcontlen > INT_MAX - len))

                return -1;

            if (len == 0 && (tt->flags & ASN1_TFLG_OPTIONAL) == 0) {

                ERR_raise(ERR_LIB_ASN1, ASN1_R_ILLEGAL_ZERO_CONTENT);

                return -1;

            }

            skcontlen += len;

        }

        sklen = ASN1_object_size(ndef, skcontlen, sktag);

        if (sklen == -1)

            return -1;

        /* If EXPLICIT need length of surrounding tag */

        if (flags & ASN1_TFLG_EXPTAG)

            ret = ASN1_object_size(ndef, sklen, ttag);

        else

            ret = sklen;

        if (!out || ret == -1)

            return ret;

        /* Now encode this lot... */

        /* EXPLICIT tag */

        if (flags & ASN1_TFLG_EXPTAG)

            ASN1_put_object(out, ndef, sklen, ttag, tclass);

        /* SET or SEQUENCE and IMPLICIT tag */

        ASN1_put_object(out, ndef, skcontlen, sktag, skaclass);

        /* And the stuff itself */

        asn1_set_seq_out(sk, out, skcontlen, ASN1_ITEM_ptr(tt->item),

            isset, iclass);

        if (ndef == 2) {

            ASN1_put_eoc(out);

            if (flags & ASN1_TFLG_EXPTAG)

                ASN1_put_eoc(out);

        }

        return ret;

    }

    if (flags & ASN1_TFLG_EXPTAG) {

        /* EXPLICIT tagging */

        /* Find length of tagged item */

        i = ASN1_item_ex_i2d(pval, NULL, ASN1_ITEM_ptr(tt->item), -1, iclass);

        if (i == 0) {

            if ((tt->flags & ASN1_TFLG_OPTIONAL) == 0) {

                ERR_raise(ERR_LIB_ASN1, ASN1_R_ILLEGAL_ZERO_CONTENT);

                return -1;

            }

            return 0;

        }

        /* Find length of EXPLICIT tag */

        ret = ASN1_object_size(ndef, i, ttag);

        if (out && ret != -1) {

            /* Output tag and item */

            ASN1_put_object(out, ndef, i, ttag, tclass);

            ASN1_item_ex_i2d(pval, out, ASN1_ITEM_ptr(tt->item), -1, iclass);

            if (ndef == 2)

                ASN1_put_eoc(out);

        }

        return ret;

    }

    /* Either normal or IMPLICIT tagging: combine class and flags */

    len = ASN1_item_ex_i2d(pval, out, ASN1_ITEM_ptr(tt->item),

        ttag, tclass | iclass);

    if (len == 0 && (tt->flags & ASN1_TFLG_OPTIONAL) == 0) {

        ERR_raise(ERR_LIB_ASN1, ASN1_R_ILLEGAL_ZERO_CONTENT);

        return -1;

    }

    return len;

}

/* Temporary structure used to hold DER encoding of items for SET OF */

typedef struct {

    unsigned char *data;

    int length;

    const ASN1_VALUE *field;

} DER_ENC;

static int der_cmp(const void *a, const void *b)

{

    const DER_ENC *d1 = a, *d2 = b;

    int cmplen, i;

    cmplen = (d1->length < d2->length) ? d1->length : d2->length;

    i = memcmp(d1->data, d2->data, cmplen);

    if (i)

        return i;

    return d1->length - d2->length;

}

/* Output the content octets of SET OF or SEQUENCE OF */

static int asn1_set_seq_out(STACK_OF(const_ASN1_VALUE) *sk,

    unsigned char **out,

    int skcontlen, const ASN1_ITEM *item,

    int do_sort, int iclass)

{

    int i, ret = 0;

    const ASN1_VALUE *skitem;

    unsigned char *tmpdat = NULL, *p = NULL;

    DER_ENC *derlst = NULL, *tder;

    if (do_sort) {

        /* Don't need to sort less than 2 items */

        if (sk_const_ASN1_VALUE_num(sk) < 2)

            do_sort = 0;

        else {

            derlst = OPENSSL_malloc(sk_const_ASN1_VALUE_num(sk)

                * sizeof(*derlst));

            if (derlst == NULL)

                return 0;

            tmpdat = OPENSSL_malloc(skcontlen);

            if (tmpdat == NULL)

                goto err;

        }

    }

    /* If not sorting just output each item */

    if (!do_sort) {

        for (i = 0; i < sk_const_ASN1_VALUE_num(sk); i++) {

            skitem = sk_const_ASN1_VALUE_value(sk, i);

            ASN1_item_ex_i2d(&skitem, out, item, -1, iclass);

        }

        return 1;

    }

    p = tmpdat;

    /* Doing sort: build up a list of each member's DER encoding */

    for (i = 0, tder = derlst; i < sk_const_ASN1_VALUE_num(sk); i++, tder++) {

        skitem = sk_const_ASN1_VALUE_value(sk, i);

        tder->data = p;

        tder->length = ASN1_item_ex_i2d(&skitem, &p, item, -1, iclass);

        tder->field = skitem;

    }

    /* Now sort them */

    qsort(derlst, sk_const_ASN1_VALUE_num(sk), sizeof(*derlst), der_cmp);

    /* Output sorted DER encoding */

    p = *out;

    for (i = 0, tder = derlst; i < sk_const_ASN1_VALUE_num(sk); i++, tder++) {

        memcpy(p, tder->data, tder->length);

        p += tder->length;

    }

    *out = p;

    /* If do_sort is 2 then reorder the STACK */

    if (do_sort == 2) {

        for (i = 0, tder = derlst; i < sk_const_ASN1_VALUE_num(sk); i++, tder++)

            (void)sk_const_ASN1_VALUE_set(sk, i, tder->field);

    }

    ret = 1;

err:

    OPENSSL_free(derlst);

    OPENSSL_free(tmpdat);

    return ret;

}

static int asn1_i2d_ex_primitive(const ASN1_VALUE **pval, unsigned char **out,

    const ASN1_ITEM *it, int tag, int aclass)

{

    int len;

    int utype;

    int usetag;

    int ndef = 0;

    utype = it->utype;

    /*

     * Get length of content octets and maybe find out the underlying type.

     */

    len = asn1_ex_i2c(pval, NULL, &utype, it);

    /*

     * If SEQUENCE, SET or OTHER then header is included in pseudo content

     * octets so don't include tag+length. We need to check here because the

     * call to asn1_ex_i2c() could change utype.

     */

    if ((utype == V_ASN1_SEQUENCE) || (utype == V_ASN1_SET) || (utype == V_ASN1_OTHER))

        usetag = 0;

    else

        usetag = 1;

    /* -1 means omit type */

    if (len == -1)

        return 0;

    /* -2 return is special meaning use ndef */

    if (len == -2) {

        ndef = 2;

        len = 0;

    }

    /* If not implicitly tagged get tag from underlying type */

    if (tag == -1)

        tag = utype;

    /* Output tag+length followed by content octets */

    if (out) {

        if (usetag)

            ASN1_put_object(out, ndef, len, tag, aclass);

        asn1_ex_i2c(pval, *out, &utype, it);

        if (ndef)

            ASN1_put_eoc(out);

        else

            *out += len;

    }

    if (usetag)

        return ASN1_object_size(ndef, len, tag);

    return len;

}

/* Produce content octets from a structure */

static int asn1_ex_i2c(const ASN1_VALUE **pval, unsigned char *cout, int *putype,

    const ASN1_ITEM *it)

{

    ASN1_BOOLEAN *tbool = NULL;

    ASN1_STRING *strtmp;

    ASN1_OBJECT *otmp;

    int utype;

    const unsigned char *cont;

    unsigned char c;

    int len;

    const ASN1_PRIMITIVE_FUNCS *pf;

    pf = it->funcs;

    if (pf && pf->prim_i2c)

        return pf->prim_i2c(pval, cout, putype, it);

    /* Should type be omitted? */

    if ((it->itype != ASN1_ITYPE_PRIMITIVE)

        || (it->utype != V_ASN1_BOOLEAN)) {

        if (*pval == NULL)

            return -1;

    }

    if (it->itype == ASN1_ITYPE_MSTRING) {

        /* If MSTRING type set the underlying type */

        strtmp = (ASN1_STRING *)*pval;

        utype = strtmp->type;

        *putype = utype;

    } else if (it->utype == V_ASN1_ANY) {

        /* If ANY set type and pointer to value */

        ASN1_TYPE *typ;

        typ = (ASN1_TYPE *)*pval;

        utype = typ->type;

        *putype = utype;

        pval = (const ASN1_VALUE **)&typ->value.asn1_value; /* actually is const */

    } else

        utype = *putype;

    switch (utype) {

    case V_ASN1_OBJECT:

        otmp = (ASN1_OBJECT *)*pval;

        cont = otmp->data;

        len = otmp->length;

        if (cont == NULL || len == 0)

            return -1;

        break;

    case V_ASN1_UNDEF:

        return -2;

    case V_ASN1_NULL:

        cont = NULL;

        len = 0;

        break;

    case V_ASN1_BOOLEAN:

        tbool = (ASN1_BOOLEAN *)pval;

        if (*tbool == -1)

            return -1;

        if (it->utype != V_ASN1_ANY) {

            /*

             * Default handling if value == size field then omit

             */

            if (*tbool && (it->size > 0))

                return -1;

            if (!*tbool && !it->size)

                return -1;

        }

        c = (unsigned char)*tbool;

        cont = &c;

        len = 1;

        break;

    case V_ASN1_BIT_STRING:

        return ossl_i2c_ASN1_BIT_STRING((const ASN1_BIT_STRING *)*pval,

            cout ? &cout : NULL);

    case V_ASN1_INTEGER:

    case V_ASN1_ENUMERATED:

        /*

         * These are all have the same content format as ASN1_INTEGER

         */

        return ossl_i2c_ASN1_INTEGER((ASN1_INTEGER *)*pval, cout ? &cout : NULL);

    case V_ASN1_OCTET_STRING:

    case V_ASN1_NUMERICSTRING:

    case V_ASN1_PRINTABLESTRING:

    case V_ASN1_T61STRING:

    case V_ASN1_VIDEOTEXSTRING:

    case V_ASN1_IA5STRING:

    case V_ASN1_UTCTIME:

    case V_ASN1_GENERALIZEDTIME:

    case V_ASN1_GRAPHICSTRING:

    case V_ASN1_VISIBLESTRING:

    case V_ASN1_GENERALSTRING:

    case V_ASN1_UNIVERSALSTRING:

    case V_ASN1_BMPSTRING:

    case V_ASN1_UTF8STRING:

    case V_ASN1_SEQUENCE:

    case V_ASN1_SET:

    default:

        /* All based on ASN1_STRING and handled the same */

        strtmp = (ASN1_STRING *)*pval;

        /* Special handling for NDEF */

        if ((it->size == ASN1_TFLG_NDEF)

            && (strtmp->flags & ASN1_STRING_FLAG_NDEF)) {

            if (cout) {

                strtmp->data = cout;

                strtmp->length = 0;

            }

            /* Special return code */

            return -2;

        }

        cont = strtmp->data;

        len = strtmp->length;

        break;

    }

    if (cout && len)

        memcpy(cout, cont, len);

    return len;

}