X-Git-Url: https://gerrit.o-ran-sc.org/r/gitweb?p=sim%2Fe2-interface.git;a=blobdiff_plain;f=e2sim%2Fasn1c%2Fconstr_CHOICE_ber.c;fp=e2sim%2Fasn1c%2Fconstr_CHOICE_ber.c;h=7ad42c763b33e15631076aad5678e0aab118c13a;hp=0000000000000000000000000000000000000000;hb=f5900596513e4359fc839ba361da085674e90b68;hpb=215d350dbe06a4c7ee370815f26128a7f7e160cb diff --git a/e2sim/asn1c/constr_CHOICE_ber.c b/e2sim/asn1c/constr_CHOICE_ber.c new file mode 100644 index 0000000..7ad42c7 --- /dev/null +++ b/e2sim/asn1c/constr_CHOICE_ber.c @@ -0,0 +1,447 @@ +/* + * Copyright (c) 2017 Lev Walkin . + * All rights reserved. + * Redistribution and modifications are permitted subject to BSD license. + */ +#include +#include + +/* + * 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 's L, even if the buffer size allows + * reading more data. + * For example, consider the buffer containing the following TLVs: + * ... + * 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 +#define NEXT_PHASE(ctx) \ + do { \ + ctx->phase++; \ + ctx->step = 0; \ + } while(0) + +/* + * Return a standardized complex structure. + */ +#undef RETURN +#define RETURN(_code) \ + do { \ + rval.code = _code; \ + rval.consumed = consumed_myself; \ + return rval; \ + } 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; + } +} + +/* + * The decoder of the CHOICE type. + */ +asn_dec_rval_t +CHOICE_decode_ber(const asn_codec_ctx_t *opt_codec_ctx, + const asn_TYPE_descriptor_t *td, void **struct_ptr, + const void *ptr, size_t size, int tag_mode) { + /* + * 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 */ + + ber_tlv_tag_t tlv_tag; /* T from TLV */ + ssize_t tag_len; /* Length of TLV's T */ + asn_dec_rval_t rval; /* Return code from subparsers */ + + ssize_t consumed_myself = 0; /* Consumed bytes from ptr */ + + 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); + + /* + * 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. + */ + + if(tag_mode || td->tags_count) { + 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) { + /* ?Subtracted below! */ + ctx->left += rval.consumed; + } + ADVANCE(rval.consumed); + } else { + ctx->left = -1; + } + + NEXT_PHASE(ctx); + + ASN_DEBUG("Structure consumes %ld bytes, buffer %ld", + (long)ctx->left, (long)size); + + /* Fall through */ + case 1: + /* + * Fetch the T from TLV. + */ + tag_len = ber_fetch_tag(ptr, LEFT, &tlv_tag); + ASN_DEBUG("In %s CHOICE tag length %d", td->name, (int)tag_len); + switch(tag_len) { + case 0: if(!SIZE_VIOLATION) RETURN(RC_WMORE); + /* Fall through */ + case -1: RETURN(RC_FAIL); + } + + do { + const asn_TYPE_tag2member_t *t2m; + asn_TYPE_tag2member_t key; + + 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 this tag */ + ssize_t skip; + + ASN_DEBUG("Skipping unknown tag %s", + ber_tlv_tag_string(tlv_tag)); + + skip = ber_skip_length(opt_codec_ctx, + BER_TLV_CONSTRUCTED(ptr), + (const char *)ptr + tag_len, + LEFT - tag_len); + + switch(skip) { + case 0: if(!SIZE_VIOLATION) RETURN(RC_WMORE); + /* Fall through */ + case -1: RETURN(RC_FAIL); + } + + ADVANCE(skip + tag_len); + RETURN(RC_OK); + } + } while(0); + + case 2: + /* + * PHASE 2. + * Read in the element. + */ + do { + asn_TYPE_member_t *elm;/* CHOICE's element */ + void *memb_ptr; /* Pointer to the member */ + void **memb_ptr2; /* Pointer to that pointer */ + + elm = &elements[ctx->step]; + + /* + * 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 */ + _set_present_idx(st, specs->pres_offset, + specs->pres_size, ctx->step + 1); + /* + * Invoke the member fetch routine according to member's type + */ + rval = elm->type->op->ber_decoder(opt_codec_ctx, elm->type, + memb_ptr2, ptr, LEFT, + elm->tag_mode); + switch(rval.code) { + case RC_OK: + break; + case RC_WMORE: /* More data expected */ + if(!SIZE_VIOLATION) { + ADVANCE(rval.consumed); + RETURN(RC_WMORE); + } + RETURN(RC_FAIL); + case RC_FAIL: /* Fatal error */ + RETURN(rval.code); + } /* switch(rval) */ + + ADVANCE(rval.consumed); + } while(0); + + NEXT_PHASE(ctx); + + /* Fall through */ + case 3: + ASN_DEBUG("CHOICE %s Leftover: %ld, size = %ld, tm=%d, tc=%d", + td->name, (long)ctx->left, (long)size, + tag_mode, td->tags_count); + + if(ctx->left > 0) { + /* + * The type must be fully decoded + * by the CHOICE member-specific decoder. + */ + RETURN(RC_FAIL); + } + + if(ctx->left == -1 + && !(tag_mode || td->tags_count)) { + /* + * This is an untagged CHOICE. + * It doesn't contain nothing + * except for the member itself, including all its tags. + * The decoding is completed. + */ + NEXT_PHASE(ctx); + break; + } + + /* + * Read in the "end of data chunks"'s. + */ + while(ctx->left < 0) { + ssize_t tl; + + 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); + } + + /* + * Expected <0><0>... + */ + if(((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++; + continue; + } + } else { + ASN_DEBUG("Unexpected continuation in %s", + td->name); + RETURN(RC_FAIL); + } + + /* UNREACHABLE */ + } + + NEXT_PHASE(ctx); + case 4: + /* No meaningful work here */ + break; + } + + RETURN(RC_OK); +} + +asn_enc_rval_t +CHOICE_encode_der(const asn_TYPE_descriptor_t *td, const void *sptr, + int tag_mode, ber_tlv_tag_t tag, 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 */ + asn_enc_rval_t erval = {0,0,0}; + const void *memb_ptr; + size_t computed_size = 0; + unsigned present; + + if(!sptr) ASN__ENCODE_FAILED; + + ASN_DEBUG("%s %s as CHOICE", + cb ? "Encoding" : "Estimating", td->name); + + present = _fetch_present_idx(sptr, + specs->pres_offset, specs->pres_size); + + /* + * If the structure was not initialized, it cannot be encoded: + * can't deduce what to encode in the choice type. + */ + if(present == 0 || present > td->elements_count) { + if(present == 0 && td->elements_count == 0) { + /* The CHOICE is empty?! */ + erval.encoded = 0; + ASN__ENCODED_OK(erval); + } + ASN__ENCODE_FAILED; + } + + /* + * Seek over the present member of the structure. + */ + 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) { + if(elm->optional) { + erval.encoded = 0; + ASN__ENCODED_OK(erval); + } + /* Mandatory element absent */ + ASN__ENCODE_FAILED; + } + } else { + memb_ptr = (const void *)((const char *)sptr + elm->memb_offset); + } + + /* + * If the CHOICE itself is tagged EXPLICIT: + * T ::= [2] EXPLICIT CHOICE { ... } + * Then emit the appropriate tags. + */ + if(tag_mode == 1 || td->tags_count) { + /* + * For this, we need to pre-compute the member. + */ + ssize_t ret; + + /* Encode member with its tag */ + erval = elm->type->op->der_encoder(elm->type, memb_ptr, + elm->tag_mode, + elm->tag, 0, 0); + if(erval.encoded == -1) + return erval; + + /* Encode CHOICE with parent or my own tag */ + ret = der_write_tags(td, erval.encoded, tag_mode, 1, tag, + cb, app_key); + if(ret == -1) + ASN__ENCODE_FAILED; + computed_size += ret; + } + + /* + * Encode the single underlying member. + */ + erval = elm->type->op->der_encoder(elm->type, memb_ptr, + elm->tag_mode, elm->tag, + cb, app_key); + if(erval.encoded == -1) + return erval; + + ASN_DEBUG("Encoded CHOICE member in %ld bytes (+%ld)", + (long)erval.encoded, (long)computed_size); + + erval.encoded += computed_size; + + return erval; +}