gecko-dev/security/nss/lib/util/derenc.c

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "secder.h"
#include "secerr.h"

#if 0
/*
 * Generic templates for individual/simple items.
 */

DERTemplate SECAnyTemplate[] = {
    { DER_ANY,
	  0, NULL, sizeof(SECItem) }
};

DERTemplate SECBitStringTemplate[] = {
    { DER_BIT_STRING,
	  0, NULL, sizeof(SECItem) }
};

DERTemplate SECBooleanTemplate[] = {
    { DER_BOOLEAN,
	  0, NULL, sizeof(SECItem) }
};

DERTemplate SECIA5StringTemplate[] = {
    { DER_IA5_STRING,
	  0, NULL, sizeof(SECItem) }
};

DERTemplate SECIntegerTemplate[] = {
    { DER_INTEGER,
	  0, NULL, sizeof(SECItem) }
};

DERTemplate SECNullTemplate[] = {
    { DER_NULL,
	  0, NULL, sizeof(SECItem) }
};

DERTemplate SECObjectIDTemplate[] = {
    { DER_OBJECT_ID,
	  0, NULL, sizeof(SECItem) }
};

DERTemplate SECOctetStringTemplate[] = {
    { DER_OCTET_STRING,
	  0, NULL, sizeof(SECItem) }
};

DERTemplate SECPrintableStringTemplate[] = {
    { DER_PRINTABLE_STRING,
	  0, NULL, sizeof(SECItem) }
};

DERTemplate SECT61StringTemplate[] = {
    { DER_T61_STRING,
	  0, NULL, sizeof(SECItem) }
};

DERTemplate SECUTCTimeTemplate[] = {
    { DER_UTC_TIME,
	  0, NULL, sizeof(SECItem) }
};

#endif

static int
header_length(DERTemplate *dtemplate, PRUint32 contents_len)
{
    PRUint32 len;
    unsigned long encode_kind, under_kind;
    PRBool explicit, optional, universal;

    encode_kind = dtemplate->kind;

    explicit = (encode_kind & DER_EXPLICIT) ? PR_TRUE : PR_FALSE;
    optional = (encode_kind & DER_OPTIONAL) ? PR_TRUE : PR_FALSE;
    universal = ((encode_kind & DER_CLASS_MASK) == DER_UNIVERSAL)
                    ? PR_TRUE
                    : PR_FALSE;

    PORT_Assert(!(explicit && universal)); /* bad templates */

    if (encode_kind & DER_POINTER) {
        if (dtemplate->sub != NULL) {
            under_kind = dtemplate->sub->kind;
            if (universal) {
                encode_kind = under_kind;
            }
        } else if (universal) {
            under_kind = encode_kind & ~DER_POINTER;
        } else {
            under_kind = dtemplate->arg;
        }
    } else if (encode_kind & DER_INLINE) {
        PORT_Assert(dtemplate->sub != NULL);
        under_kind = dtemplate->sub->kind;
        if (universal) {
            encode_kind = under_kind;
        }
    } else if (universal) {
        under_kind = encode_kind;
    } else {
        under_kind = dtemplate->arg;
    }

    /* This is only used in decoding; it plays no part in encoding.  */
    if (under_kind & DER_DERPTR)
        return 0;

    /* No header at all for an "empty" optional.  */
    if ((contents_len == 0) && optional)
        return 0;

    /* And no header for a full DER_ANY.  */
    if (encode_kind & DER_ANY)
        return 0;

    /*
     * The common case: one octet for identifier and as many octets
     * as necessary to hold the content length.
     */
    len = 1 + DER_LengthLength(contents_len);

    /* Account for the explicit wrapper, if necessary.  */
    if (explicit) {
#if 0 /*                                                         \
       * Well, I was trying to do something useful, but these    \
       * assertions are too restrictive on valid templates.      \
       * I wanted to make sure that the top-level "kind" of      \
       * a template does not also specify DER_EXPLICIT, which    \
       * should only modify a component field.  Maybe later      \
       * I can figure out a better way to detect such a problem, \
       * but for now I must remove these checks altogether.      \
       */
	/*
	 * This modifier applies only to components of a set or sequence;
	 * it should never be used on a set/sequence itself -- confirm.
	 */
	PORT_Assert (under_kind != DER_SEQUENCE);
	PORT_Assert (under_kind != DER_SET);
#endif

        len += 1 + DER_LengthLength(len + contents_len);
    }

    return len;
}

static PRUint32
contents_length(DERTemplate *dtemplate, void *src)
{
    PRUint32 len;
    unsigned long encode_kind, under_kind;
    PRBool universal;

    PORT_Assert(src != NULL);

    encode_kind = dtemplate->kind;

    universal = ((encode_kind & DER_CLASS_MASK) == DER_UNIVERSAL)
                    ? PR_TRUE
                    : PR_FALSE;
    encode_kind &= ~DER_OPTIONAL;

    if (encode_kind & DER_POINTER) {
        src = *(void **)src;
        if (src == NULL) {
            return 0;
        }
        if (dtemplate->sub != NULL) {
            dtemplate = dtemplate->sub;
            under_kind = dtemplate->kind;
            src = (void *)((char *)src + dtemplate->offset);
        } else if (universal) {
            under_kind = encode_kind & ~DER_POINTER;
        } else {
            under_kind = dtemplate->arg;
        }
    } else if (encode_kind & DER_INLINE) {
        PORT_Assert(dtemplate->sub != NULL);
        dtemplate = dtemplate->sub;
        under_kind = dtemplate->kind;
        src = (void *)((char *)src + dtemplate->offset);
    } else if (universal) {
        under_kind = encode_kind;
    } else {
        under_kind = dtemplate->arg;
    }

    /* Having any of these bits is not expected here...  */
    PORT_Assert((under_kind & (DER_EXPLICIT | DER_INLINE | DER_OPTIONAL | DER_POINTER | DER_SKIP)) == 0);

    /* This is only used in decoding; it plays no part in encoding.  */
    if (under_kind & DER_DERPTR)
        return 0;

    if (under_kind & DER_INDEFINITE) {
        PRUint32 sub_len;
        void **indp = *(void ***)src;

        if (indp == NULL)
            return 0;

        len = 0;
        under_kind &= ~DER_INDEFINITE;

        if (under_kind == DER_SET || under_kind == DER_SEQUENCE) {
            DERTemplate *tmpt = dtemplate->sub;
            PORT_Assert(tmpt != NULL);

            for (; *indp != NULL; indp++) {
                void *sub_src = (void *)((char *)(*indp) + tmpt->offset);
                sub_len = contents_length(tmpt, sub_src);
                len += sub_len + header_length(tmpt, sub_len);
            }
        } else {
            /*
    	     * XXX Lisa is not sure this code (for handling, for example,
    	     * DER_INDEFINITE | DER_OCTET_STRING) is right.
    	     */
            for (; *indp != NULL; indp++) {
                SECItem *item = (SECItem *)(*indp);
                sub_len = item->len;
                if (under_kind == DER_BIT_STRING) {
                    sub_len = (sub_len + 7) >> 3;
                    /* bit string contents involve an extra octet */
                    if (sub_len)
                        sub_len++;
                }
                if (under_kind != DER_ANY)
                    len += 1 + DER_LengthLength(sub_len);
            }
        }

        return len;
    }

    switch (under_kind) {
        case DER_SEQUENCE:
        case DER_SET: {
            DERTemplate *tmpt;
            void *sub_src;
            PRUint32 sub_len;

            len = 0;
            for (tmpt = dtemplate + 1; tmpt->kind; tmpt++) {
                sub_src = (void *)((char *)src + tmpt->offset);
                sub_len = contents_length(tmpt, sub_src);
                len += sub_len + header_length(tmpt, sub_len);
            }
        } break;

        case DER_BIT_STRING:
            len = (((SECItem *)src)->len + 7) >> 3;
            /* bit string contents involve an extra octet */
            if (len)
                len++;
            break;

        default:
            len = ((SECItem *)src)->len;
            break;
    }

    return len;
}

static unsigned char *
der_encode(unsigned char *buf, DERTemplate *dtemplate, void *src)
{
    int header_len;
    PRUint32 contents_len;
    unsigned long encode_kind, under_kind;
    PRBool explicit, universal;

    /*
     * First figure out how long the encoding will be.  Do this by
     * traversing the template from top to bottom and accumulating
     * the length of each leaf item.
     */
    contents_len = contents_length(dtemplate, src);
    header_len = header_length(dtemplate, contents_len);

    /*
     * Enough smarts was involved already, so that if both the
     * header and the contents have a length of zero, then we
     * are not doing any encoding for this element.
     */
    if (header_len == 0 && contents_len == 0)
        return buf;

    encode_kind = dtemplate->kind;

    explicit = (encode_kind & DER_EXPLICIT) ? PR_TRUE : PR_FALSE;
    encode_kind &= ~DER_OPTIONAL;
    universal = ((encode_kind & DER_CLASS_MASK) == DER_UNIVERSAL)
                    ? PR_TRUE
                    : PR_FALSE;

    if (encode_kind & DER_POINTER) {
        if (contents_len) {
            src = *(void **)src;
            PORT_Assert(src != NULL);
        }
        if (dtemplate->sub != NULL) {
            dtemplate = dtemplate->sub;
            under_kind = dtemplate->kind;
            if (universal) {
                encode_kind = under_kind;
            }
            src = (void *)((char *)src + dtemplate->offset);
        } else if (universal) {
            under_kind = encode_kind & ~DER_POINTER;
        } else {
            under_kind = dtemplate->arg;
        }
    } else if (encode_kind & DER_INLINE) {
        dtemplate = dtemplate->sub;
        under_kind = dtemplate->kind;
        if (universal) {
            encode_kind = under_kind;
        }
        src = (void *)((char *)src + dtemplate->offset);
    } else if (universal) {
        under_kind = encode_kind;
    } else {
        under_kind = dtemplate->arg;
    }

    if (explicit) {
        buf = DER_StoreHeader(buf, encode_kind,
                              (1 + DER_LengthLength(contents_len) + contents_len));
        encode_kind = under_kind;
    }

    if ((encode_kind & DER_ANY) == 0) { /* DER_ANY already contains header */
        buf = DER_StoreHeader(buf, encode_kind, contents_len);
    }

    /* If no real contents to encode, then we are done.  */
    if (contents_len == 0)
        return buf;

    if (under_kind & DER_INDEFINITE) {
        void **indp;

        indp = *(void ***)src;
        PORT_Assert(indp != NULL);

        under_kind &= ~DER_INDEFINITE;
        if (under_kind == DER_SET || under_kind == DER_SEQUENCE) {
            DERTemplate *tmpt = dtemplate->sub;
            PORT_Assert(tmpt != NULL);
            for (; *indp != NULL; indp++) {
                void *sub_src = (void *)((char *)(*indp) + tmpt->offset);
                buf = der_encode(buf, tmpt, sub_src);
            }
        } else {
            for (; *indp != NULL; indp++) {
                SECItem *item;
                int sub_len;

                item = (SECItem *)(*indp);
                sub_len = item->len;
                if (under_kind == DER_BIT_STRING) {
                    if (sub_len) {
                        int rem;

                        sub_len = (sub_len + 7) >> 3;
                        buf = DER_StoreHeader(buf, under_kind, sub_len + 1);
                        rem = (sub_len << 3) - item->len;
                        *buf++ = rem; /* remaining bits */
                    } else {
                        buf = DER_StoreHeader(buf, under_kind, 0);
                    }
                } else if (under_kind != DER_ANY) {
                    buf = DER_StoreHeader(buf, under_kind, sub_len);
                }
                PORT_Memcpy(buf, item->data, sub_len);
                buf += sub_len;
            }
        }
        return buf;
    }

    switch (under_kind) {
        case DER_SEQUENCE:
        case DER_SET: {
            DERTemplate *tmpt;
            void *sub_src;

            for (tmpt = dtemplate + 1; tmpt->kind; tmpt++) {
                sub_src = (void *)((char *)src + tmpt->offset);
                buf = der_encode(buf, tmpt, sub_src);
            }
        } break;

        case DER_BIT_STRING: {
            SECItem *item;
            int rem;

            /*
    	     * The contents length includes our extra octet; subtract
    	     * it off so we just have the real string length there.
    	     */
            contents_len--;
            item = (SECItem *)src;
            PORT_Assert(contents_len == ((item->len + 7) >> 3));
            rem = (contents_len << 3) - item->len;
            *buf++ = rem; /* remaining bits */
            PORT_Memcpy(buf, item->data, contents_len);
            buf += contents_len;
        } break;

        default: {
            SECItem *item;

            item = (SECItem *)src;
            PORT_Assert(contents_len == item->len);
            PORT_Memcpy(buf, item->data, contents_len);
            buf += contents_len;
        } break;
    }

    return buf;
}

SECStatus
DER_Encode(PLArenaPool *arena, SECItem *dest, DERTemplate *dtemplate, void *src)
{
    unsigned int contents_len, header_len;

    src = (void **)((char *)src + dtemplate->offset);

    /*
     * First figure out how long the encoding will be. Do this by
     * traversing the template from top to bottom and accumulating
     * the length of each leaf item.
     */
    contents_len = contents_length(dtemplate, src);
    header_len = header_length(dtemplate, contents_len);

    dest->len = contents_len + header_len;

    /* Allocate storage to hold the encoding */
    dest->data = (unsigned char *)PORT_ArenaAlloc(arena, dest->len);
    if (dest->data == NULL) {
        PORT_SetError(SEC_ERROR_NO_MEMORY);
        return SECFailure;
    }

    /* Now encode into the buffer */
    (void)der_encode(dest->data, dtemplate, src);

    return SECSuccess;
}