+++ /dev/null
-/*-
- * 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>
-
-#undef ADVANCE
-#define ADVANCE(num_bytes) do { \
- size_t num = num_bytes; \
- ptr = ((const char *)ptr) + num; \
- size -= num; \
- consumed_myself += num; \
- } while(0)
-#undef RETURN
-#define RETURN(_code) do { \
- asn_dec_rval_t rval; \
- rval.code = _code; \
- if(opt_ctx) opt_ctx->step = step; /* Save context */ \
- if(_code == RC_OK || opt_ctx) \
- rval.consumed = consumed_myself; \
- else \
- rval.consumed = 0; /* Context-free */ \
- return rval; \
- } while(0)
-
-/*
- * The BER decoder of any type.
- */
-asn_dec_rval_t
-ber_decode(asn_codec_ctx_t *opt_codec_ctx,
- asn_TYPE_descriptor_t *type_descriptor,
- void **struct_ptr, const void *ptr, size_t size) {
- asn_codec_ctx_t s_codec_ctx;
-
- /*
- * Stack checker requires that the codec context
- * must be allocated on the stack.
- */
- if(opt_codec_ctx) {
- if(opt_codec_ctx->max_stack_size) {
- s_codec_ctx = *opt_codec_ctx;
- opt_codec_ctx = &s_codec_ctx;
- }
- } else {
- /* If context is not given, be security-conscious anyway */
- memset(&s_codec_ctx, 0, sizeof(s_codec_ctx));
- s_codec_ctx.max_stack_size = _ASN_DEFAULT_STACK_MAX;
- opt_codec_ctx = &s_codec_ctx;
- }
-
- /*
- * Invoke type-specific decoder.
- */
- return type_descriptor->ber_decoder(opt_codec_ctx, type_descriptor,
- struct_ptr, /* Pointer to the destination structure */
- ptr, size, /* Buffer and its size */
- 0 /* Default tag mode is 0 */
- );
-}
-
-/*
- * Check the set of <TL<TL<TL...>>> tags matches the definition.
- */
-asn_dec_rval_t
-ber_check_tags(asn_codec_ctx_t *opt_codec_ctx,
- asn_TYPE_descriptor_t *td, asn_struct_ctx_t *opt_ctx,
- const void *ptr, size_t size, int tag_mode, int last_tag_form,
- ber_tlv_len_t *last_length, int *opt_tlv_form) {
- ssize_t consumed_myself = 0;
- ssize_t tag_len;
- ssize_t len_len;
- ber_tlv_tag_t tlv_tag;
- ber_tlv_len_t tlv_len;
- ber_tlv_len_t limit_len = -1;
- int expect_00_terminators = 0;
- int tlv_constr = -1; /* If CHOICE, opt_tlv_form is not given */
- int step = opt_ctx ? opt_ctx->step : 0; /* Where we left previously */
- int tagno;
-
- /*
- * Make sure we didn't exceed the maximum stack size.
- */
- if(_ASN_STACK_OVERFLOW_CHECK(opt_codec_ctx))
- RETURN(RC_FAIL);
-
- /*
- * So what does all this implicit skip stuff mean?
- * Imagine two types,
- * A ::= [5] IMPLICIT T
- * B ::= [2] EXPLICIT T
- * Where T is defined as
- * T ::= [4] IMPLICIT SEQUENCE { ... }
- *
- * Let's say, we are starting to decode type A, given the
- * following TLV stream: <5> <0>. What does this mean?
- * It means that the type A contains type T which is,
- * in turn, empty.
- * Remember though, that we are still in A. We cannot
- * just pass control to the type T decoder. Why? Because
- * the type T decoder expects <4> <0>, not <5> <0>.
- * So, we must make sure we are going to receive <5> while
- * still in A, then pass control to the T decoder, indicating
- * that the tag <4> was implicitly skipped. The decoder of T
- * hence will be prepared to treat <4> as valid tag, and decode
- * it appropriately.
- */
-
- tagno = step /* Continuing where left previously */
- + (tag_mode==1?-1:0)
- ;
- ASN_DEBUG("ber_check_tags(%s, size=%ld, tm=%d, step=%d, tagno=%d)",
- td->name, (long)size, tag_mode, step, tagno);
- /* assert(td->tags_count >= 1) May not be the case for CHOICE or ANY */
-
- if(tag_mode == 0 && tagno == td->tags_count) {
- /*
- * This must be the _untagged_ ANY type,
- * which outermost tag isn't known in advance.
- * Fetch the tag and length separately.
- */
- tag_len = ber_fetch_tag(ptr, size, &tlv_tag);
- switch(tag_len) {
- case -1: RETURN(RC_FAIL);
- case 0: RETURN(RC_WMORE);
- }
- tlv_constr = BER_TLV_CONSTRUCTED(ptr);
- len_len = ber_fetch_length(tlv_constr,
- (const char *)ptr + tag_len, size - tag_len, &tlv_len);
- switch(len_len) {
- case -1: RETURN(RC_FAIL);
- case 0: RETURN(RC_WMORE);
- }
- ASN_DEBUG("Advancing %ld in ANY case",
- (long)(tag_len + len_len));
- ADVANCE(tag_len + len_len);
- } else {
- assert(tagno < td->tags_count); /* At least one loop */
- }
- for((void)tagno; tagno < td->tags_count; tagno++, step++) {
-
- /*
- * Fetch and process T from TLV.
- */
- tag_len = ber_fetch_tag(ptr, size, &tlv_tag);
- ASN_DEBUG("Fetching tag from {%p,%ld}: "
- "len %ld, step %d, tagno %d got %s",
- ptr, (long)size,
- (long)tag_len, step, tagno,
- ber_tlv_tag_string(tlv_tag));
- switch(tag_len) {
- case -1: RETURN(RC_FAIL);
- case 0: RETURN(RC_WMORE);
- }
-
- tlv_constr = BER_TLV_CONSTRUCTED(ptr);
-
- /*
- * If {I}, don't check anything.
- * If {I,B,C}, check B and C unless we're at I.
- */
- if(tag_mode != 0 && step == 0) {
- /*
- * We don't expect tag to match here.
- * It's just because we don't know how the tag
- * is supposed to look like.
- */
- } else {
- assert(tagno >= 0); /* Guaranteed by the code above */
- if(tlv_tag != td->tags[tagno]) {
- /*
- * Unexpected tag. Too bad.
- */
- ASN_DEBUG("Expected: %s, "
- "expectation failed (tn=%d, tm=%d)",
- ber_tlv_tag_string(td->tags[tagno]),
- tagno, tag_mode
- );
- RETURN(RC_FAIL);
- }
- }
-
- /*
- * Attention: if there are more tags expected,
- * ensure that the current tag is presented
- * in constructed form (it contains other tags!).
- * If this one is the last one, check that the tag form
- * matches the one given in descriptor.
- */
- if(tagno < (td->tags_count - 1)) {
- if(tlv_constr == 0) {
- ASN_DEBUG("tlv_constr = %d, expfail",
- tlv_constr);
- RETURN(RC_FAIL);
- }
- } else {
- if(last_tag_form != tlv_constr
- && last_tag_form != -1) {
- ASN_DEBUG("last_tag_form %d != %d",
- last_tag_form, tlv_constr);
- RETURN(RC_FAIL);
- }
- }
-
- /*
- * Fetch and process L from TLV.
- */
- len_len = ber_fetch_length(tlv_constr,
- (const char *)ptr + tag_len, size - tag_len, &tlv_len);
- ASN_DEBUG("Fetchinig len = %ld", (long)len_len);
- switch(len_len) {
- case -1: RETURN(RC_FAIL);
- case 0: RETURN(RC_WMORE);
- }
-
- /*
- * FIXME
- * As of today, the chain of tags
- * must either contain several indefinite length TLVs,
- * or several definite length ones.
- * No mixing is allowed.
- */
- if(tlv_len == -1) {
- /*
- * Indefinite length.
- */
- if(limit_len == -1) {
- expect_00_terminators++;
- } else {
- ASN_DEBUG("Unexpected indefinite length "
- "in a chain of definite lengths");
- RETURN(RC_FAIL);
- }
- ADVANCE(tag_len + len_len);
- continue;
- } else {
- if(expect_00_terminators) {
- ASN_DEBUG("Unexpected definite length "
- "in a chain of indefinite lengths");
- RETURN(RC_FAIL);
- }
- }
-
- /*
- * Check that multiple TLVs specify ever decreasing length,
- * which is consistent.
- */
- if(limit_len == -1) {
- limit_len = tlv_len + tag_len + len_len;
- if(limit_len < 0) {
- /* Too great tlv_len value? */
- RETURN(RC_FAIL);
- }
- } else if(limit_len != tlv_len + tag_len + len_len) {
- /*
- * Inner TLV specifies length which is inconsistent
- * with the outer TLV's length value.
- */
- ASN_DEBUG("Outer TLV is %ld and inner is %ld",
- (long)limit_len, (long)tlv_len);
- RETURN(RC_FAIL);
- }
-
- ADVANCE(tag_len + len_len);
-
- limit_len -= (tag_len + len_len);
- if((ssize_t)size > limit_len) {
- /*
- * Make sure that we won't consume more bytes
- * from the parent frame than the inferred limit.
- */
- size = limit_len;
- }
- }
-
- if(opt_tlv_form)
- *opt_tlv_form = tlv_constr;
- if(expect_00_terminators)
- *last_length = -expect_00_terminators;
- else
- *last_length = tlv_len;
-
- RETURN(RC_OK);
-}
git.stg.codes / stg.git / blobdiff