X-Git-Url: https://git.stg.codes/stg.git/blobdiff_plain/b27841d687ec9e84983340b5581376dfb24010ea..b2b89723a2427bba8290bd6967a1ab39cbb630be:/libs/smux/constr_CHOICE_oer.c diff --git a/libs/smux/constr_CHOICE_oer.c b/libs/smux/constr_CHOICE_oer.c new file mode 100644 index 00000000..6480a961 --- /dev/null +++ b/libs/smux/constr_CHOICE_oer.c @@ -0,0 +1,380 @@ +/* + * Copyright (c) 2017 Lev Walkin . + * All rights reserved. + * Redistribution and modifications are permitted subject to BSD license. + */ +#ifndef ASN_DISABLE_OER_SUPPORT + +#include +#include +#include + +/* + * Return a standardized complex structure. + */ +#undef RETURN +#define RETURN(_code) \ + do { \ + asn_dec_rval_t rval; \ + rval.code = _code; \ + rval.consumed = consumed_myself; \ + return rval; \ + } while(0) + +#undef ADVANCE +#define ADVANCE(num_bytes) \ + do { \ + size_t num = num_bytes; \ + ptr = ((const char *)ptr) + num; \ + size -= num; \ + consumed_myself += num; \ + } while(0) + +/* + * Switch to the next phase of parsing. + */ +#undef NEXT_PHASE +#define NEXT_PHASE(ctx) \ + do { \ + ctx->phase++; \ + ctx->step = 0; \ + } while(0) +#undef SET_PHASE +#define SET_PHASE(ctx, value) \ + do { \ + ctx->phase = value; \ + ctx->step = 0; \ + } while(0) + +/* + * Tags are canonically sorted in the tag to member table. + */ +static int +_search4tag(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) + return 0; + else if(a_value < b_value) + return -1; + else + return 1; + } else if(a_class < b_class) { + return -1; + } else { + return 1; + } +} + +/* + * X.696 (08/2015) #8.7 Encoding of tags + */ +static ssize_t +oer_fetch_tag(const void *ptr, size_t size, ber_tlv_tag_t *tag_r) { + ber_tlv_tag_t val; + ber_tlv_tag_t tclass; + size_t skipped; + + if(size == 0) + return 0; + + val = *(const uint8_t *)ptr; + tclass = (val >> 6); + if((val & 0x3F) != 0x3F) { + /* #8.7.1 */ + *tag_r = ((val & 0x3F) << 2) | tclass; + return 1; + } + + /* + * Each octet contains 7 bits of useful information. + * The MSB is 0 if it is the last octet of the tag. + */ + for(val = 0, ptr = ((const char *)ptr) + 1, skipped = 2; skipped <= size; + ptr = ((const char *)ptr) + 1, skipped++) { + unsigned int oct = *(const uint8_t *)ptr; + if(oct & 0x80) { + val = (val << 7) | (oct & 0x7F); + /* + * Make sure there are at least 9 bits spare + * at the MS side of a value. + */ + if(val >> ((8 * sizeof(val)) - 9)) { + /* + * We would not be able to accomodate + * any more tag bits. + */ + return -1; + } + } else { + val = (val << 7) | oct; + *tag_r = (val << 2) | tclass; + return skipped; + } + } + + return 0; /* Want more */ +} + +asn_dec_rval_t +CHOICE_decode_oer(const asn_codec_ctx_t *opt_codec_ctx, + const asn_TYPE_descriptor_t *td, + const asn_oer_constraints_t *constraints, void **struct_ptr, + const void *ptr, size_t size) { + /* + * Bring closer parts of structure description. + */ + const asn_CHOICE_specifics_t *specs = + (const asn_CHOICE_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 */ + + ssize_t consumed_myself = 0; /* Consumed bytes from ptr */ + + (void)constraints; + + ASN_DEBUG("Decoding %s as CHOICE", 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); + switch(ctx->phase) { + case 0: { + /* + * Discover the tag. + */ + ber_tlv_tag_t tlv_tag; /* T from TLV */ + ssize_t tag_len; /* Length of TLV's T */ + + tag_len = oer_fetch_tag(ptr, size, &tlv_tag); + switch(tag_len) { + case 0: + ASN__DECODE_STARVED; + case -1: + ASN__DECODE_FAILED; + } + + do { + const asn_TYPE_tag2member_t *t2m; + asn_TYPE_tag2member_t key = {0, 0, 0, 0}; + key.el_tag = tlv_tag; + + t2m = (const asn_TYPE_tag2member_t *)bsearch( + &key, specs->tag2el, specs->tag2el_count, + sizeof(specs->tag2el[0]), _search4tag); + if(t2m) { + /* + * Found the element corresponding to the tag. + */ + NEXT_PHASE(ctx); + ctx->step = t2m->el_no; + break; + } else if(specs->ext_start == -1) { + ASN_DEBUG( + "Unexpected tag %s " + "in non-extensible CHOICE %s", + ber_tlv_tag_string(tlv_tag), td->name); + RETURN(RC_FAIL); + } else { + /* Skip open type extension */ + ASN_DEBUG( + "Not implemented skipping open type extension for tag %s", + ber_tlv_tag_string(tlv_tag)); + RETURN(RC_FAIL); + } + } while(0); + + + ADVANCE(tag_len); + } + /* Fall through */ + case 1: { + asn_TYPE_member_t *elm = &elements[ctx->step]; /* CHOICE's element */ + void *memb_ptr; /* Pointer to the member */ + void **memb_ptr2; /* Pointer to that pointer */ + asn_dec_rval_t rval; + + /* + * 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(elm->flags & ATF_POINTER) { + /* Member is a pointer to another structure */ + memb_ptr2 = (void **)((char *)st + elm->memb_offset); + } else { + /* + * A pointer to a pointer + * holding the start of the structure + */ + memb_ptr = (char *)st + elm->memb_offset; + memb_ptr2 = &memb_ptr; + } + + /* Set presence to be able to free it properly at any time */ + (void)CHOICE_variant_set_presence(td, st, ctx->step + 1); + + if(specs->ext_start >= 0 && specs->ext_start <= ctx->step) { + ssize_t got = + oer_open_type_get(opt_codec_ctx, elm->type, + elm->encoding_constraints.oer_constraints, + memb_ptr2, ptr, size); + if(got < 0) ASN__DECODE_FAILED; + if(got == 0) ASN__DECODE_STARVED; + rval.code = RC_OK; + rval.consumed = got; + } else { + rval = elm->type->op->oer_decoder( + opt_codec_ctx, elm->type, + elm->encoding_constraints.oer_constraints, memb_ptr2, ptr, + size); + } + rval.consumed += consumed_myself; + switch(rval.code) { + case RC_OK: + NEXT_PHASE(ctx); + case RC_WMORE: + break; + case RC_FAIL: + SET_PHASE(ctx, 3); /* => 3 */ + } + return rval; + } + case 2: + /* Already decoded everything */ + RETURN(RC_OK); + case 3: + /* Failed to decode, after all */ + RETURN(RC_FAIL); + } + + RETURN(RC_FAIL); +} + +/* + * X.696 (08/2015) #8.7 Encoding of tags + */ +static ssize_t +oer_put_tag(ber_tlv_tag_t tag, asn_app_consume_bytes_f *cb, void *app_key) { + uint8_t tclass = BER_TAG_CLASS(tag); + ber_tlv_tag_t tval = BER_TAG_VALUE(tag); + + if(tval < 0x3F) { + uint8_t b = (uint8_t)((tclass << 6) | tval); + if(cb(&b, 1, app_key) < 0) { + return -1; + } + return 1; + } else { + uint8_t buf[1 + 2 * sizeof(tval)]; + uint8_t *b = &buf[sizeof(buf)-1]; /* Last addressable */ + size_t encoded; + for(; ; tval >>= 7) { + if(tval >> 7) { + *b-- = 0x80 | (tval & 0x7f); + } else { + *b-- = tval & 0x7f; + break; + } + } + *b = (uint8_t)((tclass << 6) | 0x3F); + encoded = sizeof(buf) - (b - buf); + if(cb(b, encoded, app_key) < 0) { + return -1; + } + return encoded; + } + +} + +/* + * Encode as Canonical OER. + */ +asn_enc_rval_t +CHOICE_encode_oer(const asn_TYPE_descriptor_t *td, + const asn_oer_constraints_t *constraints, const void *sptr, + asn_app_consume_bytes_f *cb, void *app_key) { + const asn_CHOICE_specifics_t *specs = + (const asn_CHOICE_specifics_t *)td->specifics; + asn_TYPE_member_t *elm; /* CHOICE element */ + unsigned present; + const void *memb_ptr; + ber_tlv_tag_t tag; + ssize_t tag_len; + asn_enc_rval_t er = {0, 0, 0}; + + (void)constraints; + + if(!sptr) ASN__ENCODE_FAILED; + + ASN_DEBUG("OER %s encoding as CHOICE", td->name); + + present = CHOICE_variant_get_presence(td, sptr); + if(present == 0 || present > td->elements_count) { + ASN_DEBUG("CHOICE %s member is not selected", td->name); + ASN__ENCODE_FAILED; + } + + elm = &td->elements[present-1]; + if(elm->flags & ATF_POINTER) { + memb_ptr = + *(const void *const *)((const char *)sptr + elm->memb_offset); + if(memb_ptr == 0) { + /* Mandatory element absent */ + ASN__ENCODE_FAILED; + } + } else { + memb_ptr = (const void *)((const char *)sptr + elm->memb_offset); + } + + tag = asn_TYPE_outmost_tag(elm->type, memb_ptr, elm->tag_mode, elm->tag); + if(tag == 0) { + ASN__ENCODE_FAILED; + } + + tag_len = oer_put_tag(tag, cb, app_key); + if(tag_len < 0) { + ASN__ENCODE_FAILED; + } + + if(specs->ext_start >= 0 && (unsigned)specs->ext_start <= (present-1)) { + ssize_t encoded = oer_open_type_put(elm->type, + elm->encoding_constraints.oer_constraints, + memb_ptr, cb, app_key); + if(encoded < 0) ASN__ENCODE_FAILED; + er.encoded = tag_len + encoded; + } else { + er = elm->type->op->oer_encoder( + elm->type, elm->encoding_constraints.oer_constraints, memb_ptr, cb, + app_key); + if(er.encoded >= 0) er.encoded += tag_len; + } + + return er; +} + +#endif /* ASN_DISABLE_OER_SUPPORT */