constr_SEQUENCE.c

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/*-
 * Copyright (c) 2003, 2004, 2005, 2006, 2007 Lev Walkin <vlm@lionet.info>.
 * All rights reserved.
 * Redistribution and modifications are permitted subject to BSD license.
 */
#include <asn_internal.h>
#include <constr_SEQUENCE.h>
#include <per_opentype.h>

/*
 * Number of bytes left for this structure.
 * (ctx->left) indicates the number of bytes _transferred_ for the structure.
 * (size) contains the number of bytes in the buffer passed.
 */
#define LEFT    ((size<(size_t)ctx->left)?size:(size_t)ctx->left)

/*
 * If the subprocessor function returns with an indication that it wants
 * more data, it may well be a fatal decoding problem, because the
 * size is constrained by the <TLV>'s L, even if the buffer size allows
 * reading more data.
 * For example, consider the buffer containing the following TLVs:
 * <T:5><L:1><V> <T:6>...
 * The TLV length clearly indicates that one byte is expected in V, but
 * if the V processor returns with "want more data" even if the buffer
 * contains way more data than the V processor have seen.
 */
#define SIZE_VIOLATION  (ctx->left >= 0 && (size_t)ctx->left <= size)

/*
 * This macro "eats" the part of the buffer which is definitely "consumed",
 * i.e. was correctly converted into local representation or rightfully skipped.
 */
#undef  ADVANCE
#define ADVANCE(num_bytes)  do {        \
        size_t num = num_bytes;     \
        ptr = ((const char *)ptr) + num; \
        size -= num;            \
        if(ctx->left >= 0)      \
            ctx->left -= num;   \
        consumed_myself += num;     \
    } while(0)

/*
 * Switch to the next phase of parsing.
 */
#undef  NEXT_PHASE
#undef  PHASE_OUT
#define NEXT_PHASE(ctx) do {            \
        ctx->phase++;           \
        ctx->step = 0;          \
    } while(0)
#define PHASE_OUT(ctx)  do { ctx->phase = 10; } while(0)

/*
 * Return a standardized complex structure.
 */
#undef  RETURN
#define RETURN(_code)   do {            \
        rval.code = _code;      \
        rval.consumed = consumed_myself;\
        return rval;            \
    } while(0)

/*
 * Check whether we are inside the extensions group.
 */
#define IN_EXTENSION_GROUP(specs, memb_idx) \
    ( ((memb_idx) > (specs)->ext_after) \
    &&((memb_idx) < (specs)->ext_before))


/*
 * Tags are canonically sorted in the tag2element map.
 */
static int
_t2e_cmp(const void *ap, const void *bp) {
    const asn_TYPE_tag2member_t *a = (const asn_TYPE_tag2member_t *)ap;
    const asn_TYPE_tag2member_t *b = (const asn_TYPE_tag2member_t *)bp;

    int a_class = BER_TAG_CLASS(a->el_tag);
    int b_class = BER_TAG_CLASS(b->el_tag);

    if(a_class == b_class) {
        ber_tlv_tag_t a_value = BER_TAG_VALUE(a->el_tag);
        ber_tlv_tag_t b_value = BER_TAG_VALUE(b->el_tag);

        if(a_value == b_value) {
            if(a->el_no > b->el_no)
                return 1;
            /*
             * Important: we do not check
             * for a->el_no <= b->el_no!
             */
            return 0;
        } else if(a_value < b_value)
            return -1;
        else
            return 1;
    } else if(a_class < b_class) {
        return -1;
    } else {
        return 1;
    }
}


/*
 * The decoder of the SEQUENCE type.
 */
asn_dec_rval_t
SEQUENCE_decode_ber(asn_codec_ctx_t *opt_codec_ctx, asn_TYPE_descriptor_t *td,
    void **struct_ptr, const void *ptr, size_t size, int tag_mode) {
    /*
     * Bring closer parts of structure description.
     */
    asn_SEQUENCE_specifics_t *specs = (asn_SEQUENCE_specifics_t *)td->specifics;
    asn_TYPE_member_t *elements = td->elements;

    /*
     * Parts of the structure being constructed.
     */
    void *st = *struct_ptr; /* Target structure. */
    asn_struct_ctx_t *ctx;  /* Decoder context */

    ber_tlv_tag_t tlv_tag;  /* T from TLV */
    asn_dec_rval_t rval;    /* Return code from subparsers */

    ssize_t consumed_myself = 0;    /* Consumed bytes from ptr */
    int edx;            /* SEQUENCE element's index */

    ASN_DEBUG("Decoding %s as SEQUENCE", td->name);
    
    /*
     * Create the target structure if it is not present already.
     */
    if(st == 0) {
        st = *struct_ptr = CALLOC(1, specs->struct_size);
        if(st == 0) {
            RETURN(RC_FAIL);
        }
    }

    /*
     * Restore parsing context.
     */
    ctx = (asn_struct_ctx_t *)((char *)st + specs->ctx_offset);
    
    /*
     * Start to parse where left previously
     */
    switch(ctx->phase) {
    case 0:
        /*
         * PHASE 0.
         * Check that the set of tags associated with given structure
         * perfectly fits our expectations.
         */

        rval = ber_check_tags(opt_codec_ctx, td, ctx, ptr, size,
            tag_mode, 1, &ctx->left, 0);
        if(rval.code != RC_OK) {
            ASN_DEBUG("%s tagging check failed: %d",
                td->name, rval.code);
            return rval;
        }

        if(ctx->left >= 0)
            ctx->left += rval.consumed; /* ?Substracted below! */
        ADVANCE(rval.consumed);

        NEXT_PHASE(ctx);

        ASN_DEBUG("Structure consumes %ld bytes, buffer %ld",
            (long)ctx->left, (long)size);

        /* Fall through */
    case 1:
        /*
         * PHASE 1.
         * From the place where we've left it previously,
         * try to decode the next member from the list of
         * this structure's elements.
         * (ctx->step) stores the member being processed
         * between invocations and the microphase {0,1} of parsing
         * that member:
         *  step = (<member_number> * 2 + <microphase>).
         */
      for(edx = (ctx->step >> 1); edx < td->elements_count;
            edx++, ctx->step = (ctx->step & ~1) + 2) {
        void *memb_ptr;     /* Pointer to the member */
        void **memb_ptr2;   /* Pointer to that pointer */
        ssize_t tag_len;    /* Length of TLV's T */
        int opt_edx_end;    /* Next non-optional element */
        int use_bsearch;
        int n;

        if(ctx->step & 1)
            goto microphase2;

        /*
         * MICROPHASE 1: Synchronize decoding.
         */
        ASN_DEBUG("In %s SEQUENCE left %d, edx=%d flags=%d"
                " opt=%d ec=%d",
            td->name, (int)ctx->left, edx,
            elements[edx].flags, elements[edx].optional,
            td->elements_count);

        if(ctx->left == 0   /* No more stuff is expected */
        && (
            /* Explicit OPTIONAL specification reaches the end */
            (edx + elements[edx].optional
                    == td->elements_count)
            ||
            /* All extensions are optional */
            (IN_EXTENSION_GROUP(specs, edx)
                && specs->ext_before > td->elements_count)
           )
        ) {
            ASN_DEBUG("End of SEQUENCE %s", td->name);
            /*
             * Found the legitimate end of the structure.
             */
            PHASE_OUT(ctx);
            RETURN(RC_OK);
        }

        /*
         * Fetch the T from TLV.
         */
        tag_len = ber_fetch_tag(ptr, LEFT, &tlv_tag);
        ASN_DEBUG("Current tag in %s SEQUENCE for element %d "
            "(%s) is %s encoded in %d bytes, of frame %ld",
            td->name, edx, elements[edx].name,
            ber_tlv_tag_string(tlv_tag), (int)tag_len, (long)LEFT);
        switch(tag_len) {
        case 0: if(!SIZE_VIOLATION) RETURN(RC_WMORE);
            /* Fall through */
        case -1: RETURN(RC_FAIL);
        }

        if(ctx->left < 0 && ((const uint8_t *)ptr)[0] == 0) {
            if(LEFT < 2) {
                if(SIZE_VIOLATION)
                    RETURN(RC_FAIL);
                else
                    RETURN(RC_WMORE);
            } else if(((const uint8_t *)ptr)[1] == 0) {
            ASN_DEBUG("edx = %d, opt = %d, ec=%d",
                edx, elements[edx].optional,
                td->elements_count);
                if((edx + elements[edx].optional
                    == td->elements_count)
                || (IN_EXTENSION_GROUP(specs, edx)
                    && specs->ext_before
                        > td->elements_count)) {
                    /*
                     * Yeah, baby! Found the terminator
                     * of the indefinite length structure.
                     */
                    /*
                     * Proceed to the canonical
                     * finalization function.
                     * No advancing is necessary.
                     */
                    goto phase3;
                }
            }
        }

        /*
         * Find the next available type with this tag.
         */
        use_bsearch = 0;
        opt_edx_end = edx + elements[edx].optional + 1;
        if(opt_edx_end > td->elements_count)
            opt_edx_end = td->elements_count;   /* Cap */
        else if(opt_edx_end - edx > 8) {
            /* Limit the scope of linear search... */
            opt_edx_end = edx + 8;
            use_bsearch = 1;
            /* ... and resort to bsearch() */
        }
        for(n = edx; n < opt_edx_end; n++) {
            if(BER_TAGS_EQUAL(tlv_tag, elements[n].tag)) {
                /*
                 * Found element corresponding to the tag
                 * being looked at.
                 * Reposition over the right element.
                 */
                edx = n;
                ctx->step = 1 + 2 * edx;    /* Remember! */
                goto microphase2;
            } else if(elements[n].flags & ATF_OPEN_TYPE) {
                /*
                 * This is the ANY type, which may bear
                 * any flag whatsoever.
                 */
                edx = n;
                ctx->step = 1 + 2 * edx;    /* Remember! */
                goto microphase2;
            } else if(elements[n].tag == (ber_tlv_tag_t)-1) {
                use_bsearch = 1;
                break;
            }
        }
        if(use_bsearch) {
            /*
             * Resort to a binary search over
             * sorted array of tags.
             */
            asn_TYPE_tag2member_t *t2m;
            asn_TYPE_tag2member_t key;
            key.el_tag = tlv_tag;
            key.el_no = edx;
            t2m = (asn_TYPE_tag2member_t *)bsearch(&key,
                specs->tag2el, specs->tag2el_count,
                sizeof(specs->tag2el[0]), _t2e_cmp);
            if(t2m) {
                asn_TYPE_tag2member_t *best = 0;
                asn_TYPE_tag2member_t *t2m_f, *t2m_l;
                int edx_max = edx + elements[edx].optional;
                /*
                 * Rewind to the first element with that tag,
                 * `cause bsearch() does not guarantee order.
                 */
                t2m_f = t2m + t2m->toff_first;
                t2m_l = t2m + t2m->toff_last;
                for(t2m = t2m_f; t2m <= t2m_l; t2m++) {
                    if(t2m->el_no > edx_max) break;
                    if(t2m->el_no < edx) continue;
                    best = t2m;
                }
                if(best) {
                    edx = best->el_no;
                    ctx->step = 1 + 2 * edx;
                    goto microphase2;
                }
            }
            n = opt_edx_end;
        }
        if(n == opt_edx_end) {
            /*
             * If tag is unknown, it may be either
             * an unknown (thus, incorrect) tag,
             * or an extension (...),
             * or an end of the indefinite-length structure.
             */
            if(!IN_EXTENSION_GROUP(specs,
                edx + elements[edx].optional)) {
                ASN_DEBUG("Unexpected tag %s (at %d)",
                    ber_tlv_tag_string(tlv_tag), edx);
                ASN_DEBUG("Expected tag %s (%s)%s",
                    ber_tlv_tag_string(elements[edx].tag),
                    elements[edx].name,
                    elements[edx].optional
                        ?" or alternatives":"");
                RETURN(RC_FAIL);
            } else {
                /* Skip this tag */
                ssize_t skip;
                edx += elements[edx].optional;

                ASN_DEBUG("Skipping unexpected %s (at %d)",
                    ber_tlv_tag_string(tlv_tag), edx);
                skip = ber_skip_length(opt_codec_ctx,
                    BER_TLV_CONSTRUCTED(ptr),
                    (const char *)ptr + tag_len,
                    LEFT - tag_len);
                ASN_DEBUG("Skip length %d in %s",
                    (int)skip, td->name);
                switch(skip) {
                case 0: if(!SIZE_VIOLATION) RETURN(RC_WMORE);
                    /* Fall through */
                case -1: RETURN(RC_FAIL);
                }

                ADVANCE(skip + tag_len);
                ctx->step -= 2;
                edx--;
                continue;  /* Try again with the next tag */
            }
        }

        /*
         * MICROPHASE 2: Invoke the member-specific decoder.
         */
        ctx->step |= 1;     /* Confirm entering next microphase */
    microphase2:
        ASN_DEBUG("Inside SEQUENCE %s MF2", td->name);
        
        /*
         * Compute the position of the member inside a structure,
         * and also a type of containment (it may be contained
         * as pointer or using inline inclusion).
         */
        if(elements[edx].flags & ATF_POINTER) {
            /* Member is a pointer to another structure */
            memb_ptr2 = (void **)((char *)st + elements[edx].memb_offset);
        } else {
            /*
             * A pointer to a pointer
             * holding the start of the structure
             */
            memb_ptr = (char *)st + elements[edx].memb_offset;
            memb_ptr2 = &memb_ptr;
        }
        /*
         * Invoke the member fetch routine according to member's type
         */
        rval = elements[edx].type->ber_decoder(opt_codec_ctx,
                elements[edx].type,
                memb_ptr2, ptr, LEFT,
                elements[edx].tag_mode);
        ASN_DEBUG("In %s SEQUENCE decoded %d %s of %d "
            "in %d bytes rval.code %d, size=%d",
            td->name, edx, elements[edx].type->name,
            (int)LEFT, (int)rval.consumed, rval.code, (int)size);
        switch(rval.code) {
        case RC_OK:
            break;
        case RC_WMORE: /* More data expected */
            if(!SIZE_VIOLATION) {
                ADVANCE(rval.consumed);
                RETURN(RC_WMORE);
            }
            ASN_DEBUG("Size violation (c->l=%ld <= s=%ld)",
                (long)ctx->left, (long)size);
            /* Fall through */
        case RC_FAIL: /* Fatal error */
            RETURN(RC_FAIL);
        } /* switch(rval) */
        
        ADVANCE(rval.consumed);
      } /* for(all structure members) */

    phase3:
        ctx->phase = 3;
    case 3: /* 00 and other tags expected */
    case 4: /* only 00's expected */

        ASN_DEBUG("SEQUENCE %s Leftover: %ld, size = %ld",
            td->name, (long)ctx->left, (long)size);

        /*
         * Skip everything until the end of the SEQUENCE.
         */
        while(ctx->left) {
            ssize_t tl, ll;

            tl = ber_fetch_tag(ptr, LEFT, &tlv_tag);
            switch(tl) {
            case 0: if(!SIZE_VIOLATION) RETURN(RC_WMORE);
                /* Fall through */
            case -1: RETURN(RC_FAIL);
            }

            /*
             * If expected <0><0>...
             */
            if(ctx->left < 0
                && ((const uint8_t *)ptr)[0] == 0) {
                if(LEFT < 2) {
                    if(SIZE_VIOLATION)
                        RETURN(RC_FAIL);
                    else
                        RETURN(RC_WMORE);
                } else if(((const uint8_t *)ptr)[1] == 0) {
                    /*
                     * Correctly finished with <0><0>.
                     */
                    ADVANCE(2);
                    ctx->left++;
                    ctx->phase = 4;
                    continue;
                }
            }

            if(!IN_EXTENSION_GROUP(specs, td->elements_count)
            || ctx->phase == 4) {
                ASN_DEBUG("Unexpected continuation "
                    "of a non-extensible type "
                    "%s (SEQUENCE): %s",
                    td->name,
                    ber_tlv_tag_string(tlv_tag));
                RETURN(RC_FAIL);
            }

            ll = ber_skip_length(opt_codec_ctx,
                BER_TLV_CONSTRUCTED(ptr),
                (const char *)ptr + tl, LEFT - tl);
            switch(ll) {
            case 0: if(!SIZE_VIOLATION) RETURN(RC_WMORE);
                /* Fall through */
            case -1: RETURN(RC_FAIL);
            }

            ADVANCE(tl + ll);
        }

        PHASE_OUT(ctx);
    }
    
    RETURN(RC_OK);
}


/*
 * The DER encoder of the SEQUENCE type.
 */
asn_enc_rval_t
SEQUENCE_encode_der(asn_TYPE_descriptor_t *td,
    void *sptr, int tag_mode, ber_tlv_tag_t tag,
    asn_app_consume_bytes_f *cb, void *app_key) {
    size_t computed_size = 0;
    asn_enc_rval_t erval;
    ssize_t ret;
    int edx;

    ASN_DEBUG("%s %s as SEQUENCE",
        cb?"Encoding":"Estimating", td->name);

    /*
     * Gather the length of the underlying members sequence.
     */
    for(edx = 0; edx < td->elements_count; edx++) {
        asn_TYPE_member_t *elm = &td->elements[edx];
        void *memb_ptr;
        if(elm->flags & ATF_POINTER) {
            memb_ptr = *(void **)((char *)sptr + elm->memb_offset);
            if(!memb_ptr) {
                if(elm->optional) continue;
                /* Mandatory element is missing */
                _ASN_ENCODE_FAILED;
            }
        } else {
            memb_ptr = (void *)((char *)sptr + elm->memb_offset);
        }
        erval = elm->type->der_encoder(elm->type, memb_ptr,
            elm->tag_mode, elm->tag,
            0, 0);
        if(erval.encoded == -1)
            return erval;
        computed_size += erval.encoded;
        ASN_DEBUG("Member %d %s estimated %ld bytes",
            edx, elm->name, (long)erval.encoded);
    }

    /*
     * Encode the TLV for the sequence itself.
     */
    ret = der_write_tags(td, computed_size, tag_mode, 1, tag, cb, app_key);
    ASN_DEBUG("Wrote tags: %ld (+%ld)", (long)ret, (long)computed_size);
    if(ret == -1)
        _ASN_ENCODE_FAILED;
    erval.encoded = computed_size + ret;

    if(!cb) _ASN_ENCODED_OK(erval);

    /*
     * Encode all members.
     */
    for(edx = 0; edx < td->elements_count; edx++) {
        asn_TYPE_member_t *elm = &td->elements[edx];
        asn_enc_rval_t tmperval;
        void *memb_ptr;

        if(elm->flags & ATF_POINTER) {
            memb_ptr = *(void **)((char *)sptr + elm->memb_offset);
            if(!memb_ptr) continue;
        } else {
            memb_ptr = (void *)((char *)sptr + elm->memb_offset);
        }
        tmperval = elm->type->der_encoder(elm->type, memb_ptr,
            elm->tag_mode, elm->tag,
            cb, app_key);
        if(tmperval.encoded == -1)
            return tmperval;
        computed_size -= tmperval.encoded;
        ASN_DEBUG("Member %d %s of SEQUENCE %s encoded in %ld bytes",
            edx, elm->name, td->name, (long)tmperval.encoded);
    }

    if(computed_size != 0)
        /*
         * Encoded size is not equal to the computed size.
         */
        _ASN_ENCODE_FAILED;

    _ASN_ENCODED_OK(erval);
}


#undef  XER_ADVANCE
#define XER_ADVANCE(num_bytes)  do {            \
        size_t num = num_bytes;         \
        buf_ptr = ((const char *)buf_ptr) + num;\
        size -= num;                \
        consumed_myself += num;         \
    } while(0)

/*
 * Decode the XER (XML) data.
 */
asn_dec_rval_t
SEQUENCE_decode_xer(asn_codec_ctx_t *opt_codec_ctx, asn_TYPE_descriptor_t *td,
    void **struct_ptr, const char *opt_mname,
        const void *buf_ptr, size_t size) {
    /*
     * Bring closer parts of structure description.
     */
    asn_SEQUENCE_specifics_t *specs
        = (asn_SEQUENCE_specifics_t *)td->specifics;
    asn_TYPE_member_t *elements = td->elements;
    const char *xml_tag = opt_mname ? opt_mname : td->xml_tag;

    /*
     * ... and parts of the structure being constructed.
     */
    void *st = *struct_ptr; /* Target structure. */
    asn_struct_ctx_t *ctx;  /* Decoder context */

    asn_dec_rval_t rval;        /* Return value from a decoder */
    ssize_t consumed_myself = 0;    /* Consumed bytes from ptr */
    int edx;            /* Element index */
    int edx_end;

    /*
     * Create the target structure if it is not present already.
     */
    if(st == 0) {
        st = *struct_ptr = CALLOC(1, specs->struct_size);
        if(st == 0) RETURN(RC_FAIL);
    }

    /*
     * Restore parsing context.
     */
    ctx = (asn_struct_ctx_t *)((char *)st + specs->ctx_offset);


    /*
     * Phases of XER/XML processing:
     * Phase 0: Check that the opening tag matches our expectations.
     * Phase 1: Processing body and reacting on closing tag.
     * Phase 2: Processing inner type.
     * Phase 3: Skipping unknown extensions.
     * Phase 4: PHASED OUT
     */
    for(edx = ctx->step; ctx->phase <= 3;) {
        pxer_chunk_type_e ch_type;  /* XER chunk type */
        ssize_t ch_size;        /* Chunk size */
        xer_check_tag_e tcv;        /* Tag check value */
        asn_TYPE_member_t *elm;
        int n;

        /*
         * Go inside the inner member of a sequence.
         */
        if(ctx->phase == 2) {
            asn_dec_rval_t tmprval;
            void *memb_ptr;     /* Pointer to the member */
            void **memb_ptr2;   /* Pointer to that pointer */

            elm = &td->elements[edx];

            if(elm->flags & ATF_POINTER) {
                /* Member is a pointer to another structure */
                memb_ptr2 = (void **)((char *)st + elm->memb_offset);
            } else {
                memb_ptr = (char *)st + elm->memb_offset;
                memb_ptr2 = &memb_ptr;
            }

            /* Invoke the inner type decoder, m.b. multiple times */
            tmprval = elm->type->xer_decoder(opt_codec_ctx,
                    elm->type, memb_ptr2, elm->name,
                    buf_ptr, size);
            XER_ADVANCE(tmprval.consumed);
            if(tmprval.code != RC_OK)
                RETURN(tmprval.code);
            ctx->phase = 1; /* Back to body processing */
            ctx->step = ++edx;
            ASN_DEBUG("XER/SEQUENCE phase => %d, step => %d",
                ctx->phase, ctx->step);
            /* Fall through */
        }

        /*
         * Get the next part of the XML stream.
         */
        ch_size = xer_next_token(&ctx->context, buf_ptr, size,
            &ch_type);
        switch(ch_size) {
        case -1: RETURN(RC_FAIL);
        case 0:  RETURN(RC_WMORE);
        default:
            switch(ch_type) {
            case PXER_COMMENT:  /* Got XML comment */
            case PXER_TEXT:     /* Ignore free-standing text */
                XER_ADVANCE(ch_size);   /* Skip silently */
                continue;
            case PXER_TAG:
                break;  /* Check the rest down there */
            }
        }

        tcv = xer_check_tag(buf_ptr, ch_size, xml_tag);
        ASN_DEBUG("XER/SEQUENCE: tcv = %d, ph=%d [%s]",
            tcv, ctx->phase, xml_tag);

        /* Skip the extensions section */
        if(ctx->phase == 3) {
            switch(xer_skip_unknown(tcv, &ctx->left)) {
            case -1:
                ctx->phase = 4;
                RETURN(RC_FAIL);
            case 0:
                XER_ADVANCE(ch_size);
                continue;
            case 1:
                XER_ADVANCE(ch_size);
                ctx->phase = 1;
                continue;
            case 2:
                ctx->phase = 1;
                break;
            }
        }

        switch(tcv) {
        case XCT_CLOSING:
            if(ctx->phase == 0) break;
            ctx->phase = 0;
            /* Fall through */
        case XCT_BOTH:
            if(ctx->phase == 0) {
                if(edx >= td->elements_count
                   ||
                   /* Explicit OPTIONAL specs reaches the end */
                    (edx + elements[edx].optional
                    == td->elements_count)
                   ||
                   /* All extensions are optional */
                   (IN_EXTENSION_GROUP(specs, edx)
                    && specs->ext_before
                        > td->elements_count)
                ) {
                    XER_ADVANCE(ch_size);
                    ctx->phase = 4; /* Phase out */
                    RETURN(RC_OK);
                } else {
                    ASN_DEBUG("Premature end of XER SEQUENCE");
                    RETURN(RC_FAIL);
                }
            }
            /* Fall through */
        case XCT_OPENING:
            if(ctx->phase == 0) {
                XER_ADVANCE(ch_size);
                ctx->phase = 1; /* Processing body phase */
                continue;
            }
            /* Fall through */
        case XCT_UNKNOWN_OP:
        case XCT_UNKNOWN_BO:

            ASN_DEBUG("XER/SEQUENCE: tcv=%d, ph=%d, edx=%d",
                tcv, ctx->phase, edx);
            if(ctx->phase != 1) {
                break;  /* Really unexpected */
            }

            if(edx < td->elements_count) {
                /*
                 * Search which member corresponds to this tag.
                 */
                edx_end = edx + elements[edx].optional + 1;
                if(edx_end > td->elements_count)
                    edx_end = td->elements_count;
                for(n = edx; n < edx_end; n++) {
                    elm = &td->elements[n];
                    tcv = xer_check_tag(buf_ptr,
                        ch_size, elm->name);
                    switch(tcv) {
                    case XCT_BOTH:
                    case XCT_OPENING:
                        /*
                         * Process this member.
                         */
                        ctx->step = edx = n;
                        ctx->phase = 2;
                        break;
                    case XCT_UNKNOWN_OP:
                    case XCT_UNKNOWN_BO:
                        continue;
                    default:
                        n = edx_end;
                        break;  /* Phase out */
                    }
                    break;
                }
                if(n != edx_end)
                    continue;
            } else {
                ASN_DEBUG("Out of defined members: %d/%d",
                    edx, td->elements_count);
            }

            /* It is expected extension */
            if(IN_EXTENSION_GROUP(specs,
                edx + (edx < td->elements_count
                    ? elements[edx].optional : 0))) {
                ASN_DEBUG("Got anticipated extension at %d",
                    edx);
                /*
                 * Check for (XCT_BOTH or XCT_UNKNOWN_BO)
                 * By using a mask. Only record a pure
                 * <opening> tags.
                 */
                if(tcv & XCT_CLOSING) {
                    /* Found </extension> without body */
                } else {
                    ctx->left = 1;
                    ctx->phase = 3; /* Skip ...'s */
                }
                XER_ADVANCE(ch_size);
                continue;
            }

            /* Fall through */
        default:
            break;
        }

        ASN_DEBUG("Unexpected XML tag in SEQUENCE [%c%c%c%c%c%c]",
            size>0?((const char *)buf_ptr)[0]:'.',
            size>1?((const char *)buf_ptr)[1]:'.',
            size>2?((const char *)buf_ptr)[2]:'.',
            size>3?((const char *)buf_ptr)[3]:'.',
            size>4?((const char *)buf_ptr)[4]:'.',
            size>5?((const char *)buf_ptr)[5]:'.');
        break;
    }

    ctx->phase = 4; /* "Phase out" on hard failure */
    RETURN(RC_FAIL);
}

asn_enc_rval_t
SEQUENCE_encode_xer(asn_TYPE_descriptor_t *td, void *sptr,
    int ilevel, enum xer_encoder_flags_e flags,
        asn_app_consume_bytes_f *cb, void *app_key) {
    asn_enc_rval_t er;
    int xcan = (flags & XER_F_CANONICAL);
    int edx;

    if(!sptr)
        _ASN_ENCODE_FAILED;

    er.encoded = 0;

    for(edx = 0; edx < td->elements_count; edx++) {
        asn_enc_rval_t tmper;
        asn_TYPE_member_t *elm = &td->elements[edx];
        void *memb_ptr;
        const char *mname = elm->name;
        unsigned int mlen = strlen(mname);

        if(elm->flags & ATF_POINTER) {
            memb_ptr = *(void **)((char *)sptr + elm->memb_offset);
            if(!memb_ptr) {
                if(elm->optional)
                    continue;
                /* Mandatory element is missing */
                _ASN_ENCODE_FAILED;
            }
        } else {
            memb_ptr = (void *)((char *)sptr + elm->memb_offset);
        }

        if(!xcan) _i_ASN_TEXT_INDENT(1, ilevel);
        _ASN_CALLBACK3("<", 1, mname, mlen, ">", 1);

        /* Print the member itself */
        tmper = elm->type->xer_encoder(elm->type, memb_ptr,
            ilevel + 1, flags, cb, app_key);
        if(tmper.encoded == -1) return tmper;

        _ASN_CALLBACK3("</", 2, mname, mlen, ">", 1);
        er.encoded += 5 + (2 * mlen) + tmper.encoded;
    }

    if(!xcan) _i_ASN_TEXT_INDENT(1, ilevel - 1);

    _ASN_ENCODED_OK(er);
cb_failed:
    _ASN_ENCODE_FAILED;
}

int
SEQUENCE_print(asn_TYPE_descriptor_t *td, const void *sptr, int ilevel,
        asn_app_consume_bytes_f *cb, void *app_key) {
    int edx;
    int ret;

    if(!sptr) return (cb("<absent>", 8, app_key) < 0) ? -1 : 0;

    /* Dump preamble */
    if(cb(td->name, strlen(td->name), app_key) < 0
    || cb(" ::= {", 6, app_key) < 0)
        return -1;

    for(edx = 0; edx < td->elements_count; edx++) {
        asn_TYPE_member_t *elm = &td->elements[edx];
        const void *memb_ptr;

        if(elm->flags & ATF_POINTER) {
            memb_ptr = *(const void * const *)((const char *)sptr + elm->memb_offset);
            if(!memb_ptr) {
                if(elm->optional) continue;
                /* Print <absent> line */
                /* Fall through */
            }
        } else {
            memb_ptr = (const void *)((const char *)sptr + elm->memb_offset);
        }

        /* Indentation */
        _i_INDENT(1);

        /* Print the member's name and stuff */
        if(cb(elm->name, strlen(elm->name), app_key) < 0
        || cb(": ", 2, app_key) < 0)
            return -1;

        /* Print the member itself */
        ret = elm->type->print_struct(elm->type, memb_ptr, ilevel + 1,
            cb, app_key);
        if(ret) return ret;
    }

    ilevel--;
    _i_INDENT(1);

    return (cb("}", 1, app_key) < 0) ? -1 : 0;
}

void
SEQUENCE_free(asn_TYPE_descriptor_t *td, void *sptr, int contents_only) {
    int edx;

    if(!td || !sptr)
        return;

    ASN_DEBUG("Freeing %s as SEQUENCE", td->name);

    for(edx = 0; edx < td->elements_count; edx++) {
        asn_TYPE_member_t *elm = &td->elements[edx];
        void *memb_ptr;
        if(elm->flags & ATF_POINTER) {
            memb_ptr = *(void **)((char *)sptr + elm->memb_offset);
            if(memb_ptr)
                ASN_STRUCT_FREE(*elm->type, memb_ptr);
        } else {
            memb_ptr = (void *)((char *)sptr + elm->memb_offset);
            ASN_STRUCT_FREE_CONTENTS_ONLY(*elm->type, memb_ptr);
        }
    }

    if(!contents_only) {
        FREEMEM(sptr);
    }
}

int
SEQUENCE_constraint(asn_TYPE_descriptor_t *td, const void *sptr,
        asn_app_constraint_failed_f *ctfailcb, void *app_key) {
    int edx;

    if(!sptr) {
        _ASN_CTFAIL(app_key, td, sptr,
            "%s: value not given (%s:%d)",
            td->name, __FILE__, __LINE__);
        return -1;
    }

    /*
     * Iterate over structure members and check their validity.
     */
    for(edx = 0; edx < td->elements_count; edx++) {
        asn_TYPE_member_t *elm = &td->elements[edx];
        const void *memb_ptr;

        if(elm->flags & ATF_POINTER) {
            memb_ptr = *(const void * const *)((const char *)sptr + elm->memb_offset);
            if(!memb_ptr) {
                if(elm->optional)
                    continue;
                _ASN_CTFAIL(app_key, td, sptr,
                "%s: mandatory element %s absent (%s:%d)",
                td->name, elm->name, __FILE__, __LINE__);
                return -1;
            }
        } else {
            memb_ptr = (const void *)((const char *)sptr + elm->memb_offset);
        }

        if(elm->memb_constraints) {
            int ret = elm->memb_constraints(elm->type, memb_ptr,
                ctfailcb, app_key);
            if(ret) return ret;
        } else {
            int ret = elm->type->check_constraints(elm->type,
                memb_ptr, ctfailcb, app_key);
            if(ret) return ret;
            /*
             * Cannot inherit it earlier:
             * need to make sure we get the updated version.
             */
            elm->memb_constraints = elm->type->check_constraints;
        }
    }

    return 0;
}

asn_dec_rval_t
SEQUENCE_decode_uper(asn_codec_ctx_t *opt_codec_ctx, asn_TYPE_descriptor_t *td,
    asn_per_constraints_t *constraints, void **sptr, asn_per_data_t *pd) {
    asn_SEQUENCE_specifics_t *specs = (asn_SEQUENCE_specifics_t *)td->specifics;
    void *st = *sptr;   /* Target structure. */
    int extpresent;     /* Extension additions are present */
    uint8_t *opres;     /* Presence of optional root members */
    asn_per_data_t opmd;
    asn_dec_rval_t rv;
    int edx;

    (void)constraints;

    if(_ASN_STACK_OVERFLOW_CHECK(opt_codec_ctx))
        _ASN_DECODE_FAILED;

    if(!st) {
        st = *sptr = CALLOC(1, specs->struct_size);
        if(!st) _ASN_DECODE_FAILED;
    }

    ASN_DEBUG("Decoding %s as SEQUENCE (UPER)", td->name);

    /* Handle extensions */
    if(specs->ext_before >= 0) {
        extpresent = per_get_few_bits(pd, 1);
        if(extpresent < 0) _ASN_DECODE_STARVED;
    } else {
        extpresent = 0;
    }

    /* Prepare a place and read-in the presence bitmap */
    memset(&opmd, 0, sizeof(opmd));
    if(specs->roms_count) {
        opres = (uint8_t *)MALLOC(((specs->roms_count + 7) >> 3) + 1);
        if(!opres) _ASN_DECODE_FAILED;
        /* Get the presence map */
        if(per_get_many_bits(pd, opres, 0, specs->roms_count)) {
            FREEMEM(opres);
            _ASN_DECODE_STARVED;
        }
        opmd.buffer = opres;
        opmd.nbits = specs->roms_count;
        ASN_DEBUG("Read in presence bitmap for %s of %d bits (%x..)",
            td->name, specs->roms_count, *opres);
    } else {
        opres = 0;
    }

    /*
     * Get the sequence ROOT elements.
     */
    for(edx = 0; edx < td->elements_count; edx++) {
        asn_TYPE_member_t *elm = &td->elements[edx];
        void *memb_ptr;     /* Pointer to the member */
        void **memb_ptr2;   /* Pointer to that pointer */

        if(IN_EXTENSION_GROUP(specs, edx))
            continue;

        /* Fetch the pointer to this member */
        if(elm->flags & ATF_POINTER) {
            memb_ptr2 = (void **)((char *)st + elm->memb_offset);
        } else {
            memb_ptr = (char *)st + elm->memb_offset;
            memb_ptr2 = &memb_ptr;
        }

        /* Deal with optionality */
        if(elm->optional) {
            int present = per_get_few_bits(&opmd, 1);
            ASN_DEBUG("Member %s->%s is optional, p=%d (%d->%d)",
                td->name, elm->name, present,
                (int)opmd.nboff, (int)opmd.nbits);
            if(present == 0) {
                /* This element is not present */
                if(elm->default_value) {
                    /* Fill-in DEFAULT */
                    if(elm->default_value(1, memb_ptr2)) {
                        FREEMEM(opres);
                        _ASN_DECODE_FAILED;
                    }
                    ASN_DEBUG("Filled-in default");
                }
                /* The member is just not present */
                continue;
            }
            /* Fall through */
        }

        /* Fetch the member from the stream */
        ASN_DEBUG("Decoding member %s in %s", elm->name, td->name);
        rv = elm->type->uper_decoder(opt_codec_ctx, elm->type,
            elm->per_constraints, memb_ptr2, pd);
        if(rv.code != RC_OK) {
            ASN_DEBUG("Failed decode %s in %s",
                elm->name, td->name);
            FREEMEM(opres);
            return rv;
        }
    }

    /* Optionality map is not needed anymore */
    FREEMEM(opres);

    /*
     * Deal with extensions.
     */
    if(extpresent) {
        ssize_t bmlength;
        uint8_t *epres;     /* Presence of extension members */
        asn_per_data_t epmd;

        bmlength = uper_get_nslength(pd);
        if(bmlength < 0) _ASN_DECODE_STARVED;

        ASN_DEBUG("Extensions %ld present in %s", (long)bmlength, td->name);

        epres = (uint8_t *)MALLOC((bmlength + 15) >> 3);
        if(!epres) _ASN_DECODE_STARVED;

        /* Get the extensions map */
        if(per_get_many_bits(pd, epres, 0, bmlength))
            _ASN_DECODE_STARVED;

        memset(&epmd, 0, sizeof(epmd));
        epmd.buffer = epres;
        epmd.nbits = bmlength;
        ASN_DEBUG("Read in extensions bitmap for %s of %ld bits (%x..)",
            td->name, (long)bmlength, *epres);

        /* Go over extensions and read them in */
        for(edx = specs->ext_after + 1; edx < td->elements_count; edx++) {
        asn_TYPE_member_t *elm = &td->elements[edx];
        void *memb_ptr;     /* Pointer to the member */
        void **memb_ptr2;   /* Pointer to that pointer */
        int present;

        if(!IN_EXTENSION_GROUP(specs, edx)) {
            ASN_DEBUG("%d is not extension", edx);
            continue;
        }

        /* Fetch the pointer to this member */
        if(elm->flags & ATF_POINTER) {
            memb_ptr2 = (void **)((char *)st + elm->memb_offset);
        } else {
            memb_ptr = (void *)((char *)st + elm->memb_offset);
            memb_ptr2 = &memb_ptr;
        }

        present = per_get_few_bits(&epmd, 1);
        if(present <= 0) {
            if(present < 0) break;  /* No more extensions */
            continue;
        }

        ASN_DEBUG("Decoding member %s in %s %p", elm->name, td->name, *memb_ptr2);
        rv = uper_open_type_get(opt_codec_ctx, elm->type,
            elm->per_constraints, memb_ptr2, pd);
        if(rv.code != RC_OK) {
            FREEMEM(epres);
            return rv;
        }
        }

        /* Skip over overflow extensions which aren't present
         * in this system's version of the protocol */
        for(;;) {
            ASN_DEBUG("Getting overflow extensions");
            switch(per_get_few_bits(&epmd, 1)) {
            case -1: break;
            case 0: continue;
            default:
                if(uper_open_type_skip(opt_codec_ctx, pd)) {
                    FREEMEM(epres);
                    _ASN_DECODE_STARVED;
                }
            }
            break;
        }

        FREEMEM(epres);
    }

    /* Fill DEFAULT members in extensions */
    for(edx = specs->roms_count; edx < specs->roms_count
            + specs->aoms_count; edx++) {
        asn_TYPE_member_t *elm = &td->elements[edx];
        void **memb_ptr2;   /* Pointer to member pointer */

        if(!elm->default_value) continue;

        /* Fetch the pointer to this member */
        if(elm->flags & ATF_POINTER) {
            memb_ptr2 = (void **)((char *)st
                    + elm->memb_offset);
            if(*memb_ptr2) continue;
        } else {
            continue;   /* Extensions are all optionals */
        }

        /* Set default value */
        if(elm->default_value(1, memb_ptr2)) {
            _ASN_DECODE_FAILED;
        }
    }

    rv.consumed = 0;
    rv.code = RC_OK;
    return rv;
}

static int
SEQUENCE_handle_extensions(asn_TYPE_descriptor_t *td, void *sptr,
        asn_per_outp_t *po1, asn_per_outp_t *po2) {
    asn_SEQUENCE_specifics_t *specs
        = (asn_SEQUENCE_specifics_t *)td->specifics;
    int exts_present = 0;
    int exts_count = 0;
    int edx;

    if(specs->ext_before < 0)
        return 0;

    /* Find out which extensions are present */
    for(edx = specs->ext_after + 1; edx < td->elements_count; edx++) {
        asn_TYPE_member_t *elm = &td->elements[edx];
        void *memb_ptr;     /* Pointer to the member */
        void **memb_ptr2;   /* Pointer to that pointer */
        int present;

        if(!IN_EXTENSION_GROUP(specs, edx)) {
            ASN_DEBUG("%s (@%d) is not extension", elm->type->name, edx);
            continue;
        }

        /* Fetch the pointer to this member */
        if(elm->flags & ATF_POINTER) {
            memb_ptr2 = (void **)((char *)sptr + elm->memb_offset);
            present = (*memb_ptr2 != 0);
        } else {
            memb_ptr = (void *)((char *)sptr + elm->memb_offset);
            memb_ptr2 = &memb_ptr;
            present = 1;
        }

        ASN_DEBUG("checking %s (@%d) present => %d",
            elm->type->name, edx, present);
        exts_count++;
        exts_present += present;

        /* Encode as presence marker */
        if(po1 && per_put_few_bits(po1, present, 1))
            return -1;
        /* Encode as open type field */
        if(po2 && present && uper_open_type_put(elm->type,
                elm->per_constraints, *memb_ptr2, po2))
            return -1;

    }

    return exts_present ? exts_count : 0;
}

asn_enc_rval_t
SEQUENCE_encode_uper(asn_TYPE_descriptor_t *td,
    asn_per_constraints_t *constraints, void *sptr, asn_per_outp_t *po) {
    asn_SEQUENCE_specifics_t *specs
        = (asn_SEQUENCE_specifics_t *)td->specifics;
    asn_enc_rval_t er;
    int n_extensions;
    int edx;
    int i;

    (void)constraints;

    if(!sptr)
        _ASN_ENCODE_FAILED;

    er.encoded = 0;

    ASN_DEBUG("Encoding %s as SEQUENCE (UPER)", td->name);


    /*
     * X.691#18.1 Whether structure is extensible
     * and whether to encode extensions
     */
    if(specs->ext_before >= 0) {
        n_extensions = SEQUENCE_handle_extensions(td, sptr, 0, 0);
        per_put_few_bits(po, n_extensions ? 1 : 0, 1);
    } else {
        n_extensions = 0;   /* There are no extensions to encode */
    }

    /* Encode a presence bitmap */
    for(i = 0; i < specs->roms_count; i++) {
        asn_TYPE_member_t *elm;
        void *memb_ptr;     /* Pointer to the member */
        void **memb_ptr2;   /* Pointer to that pointer */
        int present;

        edx = specs->oms[i];
        elm = &td->elements[edx];

        /* Fetch the pointer to this member */
        if(elm->flags & ATF_POINTER) {
            memb_ptr2 = (void **)((char *)sptr + elm->memb_offset);
            present = (*memb_ptr2 != 0);
        } else {
            memb_ptr = (void *)((char *)sptr + elm->memb_offset);
            memb_ptr2 = &memb_ptr;
            present = 1;
        }

        /* Eliminate default values */
        if(present && elm->default_value
        && elm->default_value(0, memb_ptr2) == 1)
            present = 0;

        ASN_DEBUG("Element %s %s %s->%s is %s",
            elm->flags & ATF_POINTER ? "ptr" : "inline",
            elm->default_value ? "def" : "wtv",
            td->name, elm->name, present ? "present" : "absent");
        if(per_put_few_bits(po, present, 1))
            _ASN_ENCODE_FAILED;
    }

    /*
     * Encode the sequence ROOT elements.
     */
    ASN_DEBUG("ext_after = %d, ec = %d, eb = %d", specs->ext_after, td->elements_count, specs->ext_before);
    for(edx = 0; edx < ((specs->ext_after < 0)
        ? td->elements_count : specs->ext_before - 1); edx++) {

        asn_TYPE_member_t *elm = &td->elements[edx];
        void *memb_ptr;     /* Pointer to the member */
        void **memb_ptr2;   /* Pointer to that pointer */

        if(IN_EXTENSION_GROUP(specs, edx))
            continue;

        ASN_DEBUG("About to encode %s", elm->type->name);

        /* Fetch the pointer to this member */
        if(elm->flags & ATF_POINTER) {
            memb_ptr2 = (void **)((char *)sptr + elm->memb_offset);
            if(!*memb_ptr2) {
                ASN_DEBUG("Element %s %d not present",
                    elm->name, edx);
                if(elm->optional)
                    continue;
                /* Mandatory element is missing */
                _ASN_ENCODE_FAILED;
            }
        } else {
            memb_ptr = (void *)((char *)sptr + elm->memb_offset);
            memb_ptr2 = &memb_ptr;
        }

        /* Eliminate default values */
        if(elm->default_value && elm->default_value(0, memb_ptr2) == 1)
            continue;

        ASN_DEBUG("Encoding %s->%s", td->name, elm->name);
        er = elm->type->uper_encoder(elm->type, elm->per_constraints,
            *memb_ptr2, po);
        if(er.encoded == -1)
            return er;
    }

    /* No extensions to encode */
    if(!n_extensions) _ASN_ENCODED_OK(er);

    ASN_DEBUG("Length of %d bit-map", n_extensions);
    /* #18.8. Write down the presence bit-map length. */
    if(uper_put_nslength(po, n_extensions))
        _ASN_ENCODE_FAILED;

    ASN_DEBUG("Bit-map of %d elements", n_extensions);
    /* #18.7. Encoding the extensions presence bit-map. */
    /* TODO: act upon NOTE in #18.7 for canonical PER */
    if(SEQUENCE_handle_extensions(td, sptr, po, 0) != n_extensions)
        _ASN_ENCODE_FAILED;

    ASN_DEBUG("Writing %d extensions", n_extensions);
    /* #18.9. Encode extensions as open type fields. */
    if(SEQUENCE_handle_extensions(td, sptr, 0, po) != n_extensions)
        _ASN_ENCODE_FAILED;

    _ASN_ENCODED_OK(er);
}