asn_codecs_prim.c

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/*-
 * Copyright (c) 2003, 2004 Lev Walkin <vlm@lionet.info>. All rights reserved.
 * Redistribution and modifications are permitted subject to BSD license.
 */
#include <asn_internal.h>
#include <asn_codecs_prim.h>
#include <errno.h>

/*
 * Decode an always-primitive type.
 */
asn_dec_rval_t
ber_decode_primitive(asn_codec_ctx_t *opt_codec_ctx,
    asn_TYPE_descriptor_t *td,
    void **sptr, const void *buf_ptr, size_t size, int tag_mode) {
    ASN__PRIMITIVE_TYPE_t *st = (ASN__PRIMITIVE_TYPE_t *)*sptr;
    asn_dec_rval_t rval;
    ber_tlv_len_t length = 0; // =0 to avoid [incorrect] warning.

    /*
     * If the structure is not there, allocate it.
     */
    if(st == NULL) {
        st = (ASN__PRIMITIVE_TYPE_t *)CALLOC(1, sizeof(*st));
        if(st == NULL) _ASN_DECODE_FAILED;
        *sptr = (void *)st;
    }

    ASN_DEBUG("Decoding %s as plain primitive (tm=%d)",
        td->name, tag_mode);

    /*
     * Check tags and extract value length.
     */
    rval = ber_check_tags(opt_codec_ctx, td, 0, buf_ptr, size,
            tag_mode, 0, &length, 0);
    if(rval.code != RC_OK)
        return rval;

    ASN_DEBUG("%s length is %d bytes", td->name, (int)length);

    /*
     * Make sure we have this length.
     */
    buf_ptr = ((const char *)buf_ptr) + rval.consumed;
    size -= rval.consumed;
    if(length > (ber_tlv_len_t)size) {
        rval.code = RC_WMORE;
        rval.consumed = 0;
        return rval;
    }

    st->size = (int)length;
    /* The following better be optimized away. */
    if(sizeof(st->size) != sizeof(length)
            && (ber_tlv_len_t)st->size != length) {
        st->size = 0;
        _ASN_DECODE_FAILED;
    }

    st->buf = (uint8_t *)MALLOC(length + 1);
    if(!st->buf) {
        st->size = 0;
        _ASN_DECODE_FAILED;
    }

    memcpy(st->buf, buf_ptr, length);
    st->buf[length] = '\0';     /* Just in case */

    rval.code = RC_OK;
    rval.consumed += length;

    ASN_DEBUG("Took %ld/%ld bytes to encode %s",
        (long)rval.consumed,
        (long)length, td->name);

    return rval;
}

/*
 * Encode an always-primitive type using DER.
 */
asn_enc_rval_t
der_encode_primitive(asn_TYPE_descriptor_t *td, void *sptr,
    int tag_mode, ber_tlv_tag_t tag,
    asn_app_consume_bytes_f *cb, void *app_key) {
    asn_enc_rval_t erval;
    ASN__PRIMITIVE_TYPE_t *st = (ASN__PRIMITIVE_TYPE_t *)sptr;

    ASN_DEBUG("%s %s as a primitive type (tm=%d)",
        cb?"Encoding":"Estimating", td->name, tag_mode);

    erval.encoded = der_write_tags(td, st->size, tag_mode, 0, tag,
        cb, app_key);
    ASN_DEBUG("%s wrote tags %d", td->name, (int)erval.encoded);
    if(erval.encoded == -1) {
        erval.failed_type = td;
        erval.structure_ptr = sptr;
        return erval;
    }

    if(cb && st->buf) {
        if(cb(st->buf, st->size, app_key) < 0) {
            erval.encoded = -1;
            erval.failed_type = td;
            erval.structure_ptr = sptr;
            return erval;
        }
    } else {
        assert(st->buf || st->size == 0);
    }

    erval.encoded += st->size;
    _ASN_ENCODED_OK(erval);
}

void
ASN__PRIMITIVE_TYPE_free(asn_TYPE_descriptor_t *td, void *sptr,
        int contents_only) {
    ASN__PRIMITIVE_TYPE_t *st = (ASN__PRIMITIVE_TYPE_t *)sptr;

    if(!td || !sptr)
        return;

    ASN_DEBUG("Freeing %s as a primitive type", td->name);

    if(st->buf)
        FREEMEM(st->buf);

    if(!contents_only)
        FREEMEM(st);
}


/*
 * Local internal type passed around as an argument.
 */
struct xdp_arg_s {
    asn_TYPE_descriptor_t *type_descriptor;
    void *struct_key;
    xer_primitive_body_decoder_f *prim_body_decoder;
    int decoded_something;
    int want_more;
};

/*
 * Since some kinds of primitive values can be encoded using value-specific
 * tags (<MINUS-INFINITY>, <enum-element>, etc), the primitive decoder must
 * be supplied with such tags to parse them as needed.
 */
static int
xer_decode__unexpected_tag(void *key, const void *chunk_buf, size_t chunk_size) {
    struct xdp_arg_s *arg = (struct xdp_arg_s *)key;
    enum xer_pbd_rval bret;

    /*
     * The chunk_buf is guaranteed to start at '<'.
     */
    assert(chunk_size && ((const char *)chunk_buf)[0] == 0x3c);

    /*
     * Decoding was performed once already. Prohibit doing it again.
     */
    if(arg->decoded_something)
        return -1;

    bret = arg->prim_body_decoder(arg->type_descriptor,
        arg->struct_key, chunk_buf, chunk_size);
    switch(bret) {
    case XPBD_SYSTEM_FAILURE:
    case XPBD_DECODER_LIMIT:
    case XPBD_BROKEN_ENCODING:
        break;
    case XPBD_BODY_CONSUMED:
        /* Tag decoded successfully */
        arg->decoded_something = 1;
        /* Fall through */
    case XPBD_NOT_BODY_IGNORE:  /* Safe to proceed further */
        return 0;
    }

    return -1;
}

static ssize_t
xer_decode__primitive_body(void *key, const void *chunk_buf, size_t chunk_size, int have_more) {
    struct xdp_arg_s *arg = (struct xdp_arg_s *)key;
    enum xer_pbd_rval bret;
    size_t lead_wsp_size;

    if(arg->decoded_something) {
        if(xer_whitespace_span(chunk_buf, chunk_size) == chunk_size) {
            /*
             * Example:
             * "<INTEGER>123<!--/--> </INTEGER>"
             *                      ^- chunk_buf position.
             */
            return chunk_size;
        }
        /*
         * Decoding was done once already. Prohibit doing it again.
         */
        return -1;
    }

    if(!have_more) {
        /*
         * If we've received something like "1", we can't really
         * tell whether it is really `1` or `123`, until we know
         * that there is no more data coming.
         * The have_more argument will be set to 1 once something
         * like this is available to the caller of this callback:
         * "1<tag_start..."
         */
        arg->want_more = 1;
        return -1;
    }

    lead_wsp_size = xer_whitespace_span(chunk_buf, chunk_size);
    chunk_buf = (const char *)chunk_buf + lead_wsp_size;
    chunk_size -= lead_wsp_size;

    bret = arg->prim_body_decoder(arg->type_descriptor,
        arg->struct_key, chunk_buf, chunk_size);
    switch(bret) {
    case XPBD_SYSTEM_FAILURE:
    case XPBD_DECODER_LIMIT:
    case XPBD_BROKEN_ENCODING:
        break;
    case XPBD_BODY_CONSUMED:
        /* Tag decoded successfully */
        arg->decoded_something = 1;
        /* Fall through */
    case XPBD_NOT_BODY_IGNORE:  /* Safe to proceed further */
        return lead_wsp_size + chunk_size;
    }

    return -1;
}


asn_dec_rval_t
xer_decode_primitive(asn_codec_ctx_t *opt_codec_ctx,
    asn_TYPE_descriptor_t *td,
    void **sptr,
    size_t struct_size,
    const char *opt_mname,
    const void *buf_ptr, size_t size,
    xer_primitive_body_decoder_f *prim_body_decoder
) {
    const char *xml_tag = opt_mname ? opt_mname : td->xml_tag;
    asn_struct_ctx_t s_ctx;
    struct xdp_arg_s s_arg;
    asn_dec_rval_t rc;

    /*
     * Create the structure if does not exist.
     */
    if(!*sptr) {
        *sptr = CALLOC(1, struct_size);
        if(!*sptr) _ASN_DECODE_FAILED;
    }

    memset(&s_ctx, 0, sizeof(s_ctx));
    s_arg.type_descriptor = td;
    s_arg.struct_key = *sptr;
    s_arg.prim_body_decoder = prim_body_decoder;
    s_arg.decoded_something = 0;
    s_arg.want_more = 0;

    rc = xer_decode_general(opt_codec_ctx, &s_ctx, &s_arg,
        xml_tag, buf_ptr, size,
        xer_decode__unexpected_tag, xer_decode__primitive_body);
    switch(rc.code) {
    case RC_OK:
        if(!s_arg.decoded_something) {
            char ch;
            ASN_DEBUG("Primitive body is not recognized, "
                "supplying empty one");
            /*
             * Decoding opportunity has come and gone.
             * Where's the result?
             * Try to feed with empty body, see if it eats it.
             */
            if(prim_body_decoder(s_arg.type_descriptor,
                s_arg.struct_key, &ch, 0)
                    != XPBD_BODY_CONSUMED) {
                /*
                 * This decoder does not like empty stuff.
                 */
                _ASN_DECODE_FAILED;
            }
        }
        break;
    case RC_WMORE:
        /*
         * Redo the whole thing later.
         * We don't have a context to save intermediate parsing state.
         */
        rc.consumed = 0;
        break;
    case RC_FAIL:
        rc.consumed = 0;
        if(s_arg.want_more)
            rc.code = RC_WMORE;
        else
            _ASN_DECODE_FAILED;
        break;
    }
    return rc;
}