skeletons/INTEGER_oer.c

/*
 * Copyright (c) 2017 Lev Walkin <vlm@lionet.info>.
 * All rights reserved.
 * Redistribution and modifications are permitted subject to BSD license.
 */
#ifndef ASN_DISABLE_OER_SUPPORT

#include <asn_internal.h>
#include <INTEGER.h>
#include <errno.h>

asn_dec_rval_t
INTEGER_decode_oer(asn_codec_ctx_t *opt_codec_ctx, asn_TYPE_descriptor_t *td,
                   asn_oer_constraints_t *constraints, void **sptr,
                   const void *ptr, size_t size) {
    asn_INTEGER_specifics_t *specs = (asn_INTEGER_specifics_t *)td->specifics;
    asn_dec_rval_t rval = {RC_OK, 0};
    INTEGER_t *st = (INTEGER_t *)*sptr;
    asn_oer_constraint_t *ct;
    size_t req_bytes = 0; /* 0 = length determinant is required */

    (void)opt_codec_ctx;
    (void)specs;

    if(!st) {
        st = (INTEGER_t *)(*sptr = CALLOC(1, sizeof(*st)));
        if(!st) ASN__DECODE_FAILED;
    }

    FREEMEM(st->buf);
    st->buf = 0;
    st->size = 0;

    if(!constraints) constraints = td->oer_constraints;
    ct = constraints ? &constraints->value : 0;

    if(ct && (ct->flags & AOC_HAS_LOWER_BOUND) && ct->lower_bound >= 0) {
        /* X.969 08/2015 10.2(a) */
        unsigned msb;   /* Most significant bit */
        size_t useful_size;

        intmax_t ub = ct->upper_bound;
        if(ct->flags & AOC_HAS_UPPER_BOUND) {
            if(ub <= 255) {
                req_bytes = 1;
            } else if(ub <= 65535) {
                req_bytes = 2;
            } else if(ub <= 4294967295UL) {
                req_bytes = 4;
            } else if(ub <= 18446744073709551615ULL) {
                req_bytes = 8;
            }
        }

        if(req_bytes == 0) {    /* #8.6, using length determinant */
            ssize_t consumed = oer_fetch_length(ptr, size, &req_bytes);
            if(consumed == 0) {
                ASN__DECODE_STARVED;
            } else if(consumed == -1) {
                ASN__DECODE_FAILED;
            }
            rval.consumed += consumed;
            ptr = (const char *)ptr + consumed;
            size -= consumed;
        }

        if(req_bytes > size) {
            ASN__DECODE_STARVED;
        }

        /* Check most significant bit */
        msb = *(const uint8_t *)ptr >> 7; /* yields 0 or 1 */
        useful_size = msb + req_bytes;
        st->buf = (uint8_t *)MALLOC(useful_size + 1);
        if(!st->buf) {
            ASN__DECODE_FAILED;
        }

        /*
         * Record a large unsigned in a way not to confuse it
         * with signed value.
         */
        st->buf[0] = '\0';
        memcpy(st->buf + msb, ptr, req_bytes);
        st->buf[useful_size] = '\0';    /* Just in case, 0-terminate */
        st->size = useful_size;

        rval.consumed += req_bytes;
        return rval;
    } else if(ct && (ct->flags & AOC_HAS_LOWER_BOUND)) {
        /* X.969 08/2015 10.2(b) - no lower bound or negative lower bound */

        intmax_t lb = ct->lower_bound;
        intmax_t ub = ct->upper_bound;

        if(ct->flags & AOC_HAS_UPPER_BOUND) {
            if(lb >= -128 && ub <= 127) {
                req_bytes = 1;
            } else if(lb >= -32768 && ub <= 32767) {
                req_bytes = 2;
            } else if(lb >= -2147483648L && ub <= 2147483647L) {
                req_bytes = 4;
            } else if(lb >= -9223372036854775808LL
                      && ub <= 9223372036854775807LL) {
                req_bytes = 8;
            }
        }
    }

    /* No lower bound and no upper bound, effectively */

    if(req_bytes == 0) {    /* #8.6, using length determinant */
        ssize_t consumed = oer_fetch_length(ptr, size, &req_bytes);
        if(consumed == 0) {
            ASN__DECODE_STARVED;
        } else if(consumed == -1) {
            ASN__DECODE_FAILED;
        }
        rval.consumed += consumed;
        ptr = (const char *)ptr + consumed;
        size -= consumed;
    }

    if(req_bytes > size) {
        ASN__DECODE_STARVED;
    }

    st->buf = (uint8_t *)MALLOC(req_bytes + 1);
    if(!st->buf) {
        ASN__DECODE_FAILED;
    }

    memcpy(st->buf, ptr, req_bytes);
    st->buf[req_bytes] = '\0'; /* Just in case, 0-terminate */
    st->size = req_bytes;

    rval.consumed += req_bytes;
    return rval;
}

#endif  /* ASN_DISABLE_OER_SUPPORT */