secasn1d.c

来自「支持SSL v2/v3, TLS, PKCS #5, PKCS #7, PKCS」· C语言 代码 · 共 2,402 行 · 第 1/5 页

	    item = (SECItem *)(state->dest);
	    item->data = NULL;
	    item->len = 0;
	}
	state->place = afterEndOfContents;
	break;

      case SEC_ASN1_BMP_STRING:
	/* Error if length is not divisable by 2 */
	if (state->contents_length % 2) {
	   state->top->status = decodeError;
	   break;
	}   
	/* otherwise, handle as other string types */
	goto regular_string_type;

      case SEC_ASN1_UNIVERSAL_STRING:
	/* Error if length is not divisable by 4 */
	if (state->contents_length % 4) {
	   state->top->status = decodeError;
	   break;
	}   
	/* otherwise, handle as other string types */
	goto regular_string_type;

      case SEC_ASN1_SKIP:
      case SEC_ASN1_ANY:
      case SEC_ASN1_ANY_CONTENTS:
	/*
	 * These are not (necessarily) strings, but they need nearly
	 * identical handling (especially when we need to deal with
	 * constructed sub-pieces), so we pretend they are.
	 */
	/* fallthru */
regular_string_type:
      case SEC_ASN1_BIT_STRING:
      case SEC_ASN1_IA5_STRING:
      case SEC_ASN1_OCTET_STRING:
      case SEC_ASN1_PRINTABLE_STRING:
      case SEC_ASN1_T61_STRING:
      case SEC_ASN1_UTC_TIME:
      case SEC_ASN1_UTF8_STRING:
      case SEC_ASN1_VISIBLE_STRING:
	/*
	 * We are allocating for a primitive or a constructed string.
	 * If it is a constructed string, it may also be indefinite-length.
	 * If it is primitive, the length can (legally) be zero.
	 * Our first order of business is to allocate the memory for
	 * the string, if we can (if we know the length).
	 */
	item = (SECItem *)(state->dest);

	/*
	 * If the item is a definite-length constructed string, then
	 * the contents_length is actually larger than what we need
	 * (because it also counts each intermediate header which we
	 * will be throwing away as we go), but it is a perfectly good
	 * upper bound that we just allocate anyway, and then concat
	 * as we go; we end up wasting a few extra bytes but save a
	 * whole other copy.
	 */
	alloc_len = state->contents_length;
	poolp = NULL;	/* quiet compiler warnings about unused... */

	if (item == NULL || state->top->filter_only) {
	    if (item != NULL) {
		item->data = NULL;
		item->len = 0;
	    }
	    alloc_len = 0;
	} else if (state->substring) {
	    /*
	     * If we are a substring of a constructed string, then we may
	     * not have to allocate anything (because our parent, the
	     * actual constructed string, did it for us).  If we are a
	     * substring and we *do* have to allocate, that means our
	     * parent is an indefinite-length, so we allocate from our pool;
	     * later our parent will copy our string into the aggregated
	     * whole and free our pool allocation.
	     */
	    if (item->data == NULL) {
		PORT_Assert (item->len == 0);
		poolp = state->top->our_pool;
	    } else {
		alloc_len = 0;
	    }
	} else {
	    item->len = 0;
	    item->data = NULL;
	    poolp = state->top->their_pool;
	}

	if (alloc_len || ((! state->indefinite)
			  && (state->subitems_head != NULL))) {
	    struct subitem *subitem;
	    int len;

	    PORT_Assert (item->len == 0 && item->data == NULL);
	    /*
	     * Check for and handle an ANY which has stashed aside the
	     * header (identifier and length) bytes for us to include
	     * in the saved contents.
	     */
	    if (state->subitems_head != NULL) {
		PORT_Assert (state->underlying_kind == SEC_ASN1_ANY);
		for (subitem = state->subitems_head;
		     subitem != NULL; subitem = subitem->next)
		    alloc_len += subitem->len;
	    }

	    item->data = (unsigned char*)sec_asn1d_zalloc (poolp, alloc_len);
	    if (item->data == NULL) {
		state->top->status = decodeError;
		break;
	    }

	    len = 0;
	    for (subitem = state->subitems_head;
		 subitem != NULL; subitem = subitem->next) {
		PORT_Memcpy (item->data + len, subitem->data, subitem->len);
		len += subitem->len;
	    }
	    item->len = len;

	    /*
	     * Because we use arenas and have a mark set, we later free
	     * everything we have allocated, so this does *not* present
	     * a memory leak (it is just temporarily left dangling).
	     */
	    state->subitems_head = state->subitems_tail = NULL;
	}

	if (state->contents_length == 0 && (! state->indefinite)) {
	    /*
	     * A zero-length simple or constructed string; we are done.
	     */
	    state->place = afterEndOfContents;
	} else if (state->found_tag_modifiers & SEC_ASN1_CONSTRUCTED) {
	    const SEC_ASN1Template *sub;

	    switch (state->underlying_kind) {
	      case SEC_ASN1_ANY:
	      case SEC_ASN1_ANY_CONTENTS:
		sub = SEC_AnyTemplate;
		break;
	      case SEC_ASN1_BIT_STRING:
		sub = SEC_BitStringTemplate;
		break;
	      case SEC_ASN1_BMP_STRING:
		sub = SEC_BMPStringTemplate;
		break;
	      case SEC_ASN1_GENERALIZED_TIME:
		sub = SEC_GeneralizedTimeTemplate;
		break;
	      case SEC_ASN1_IA5_STRING:
		sub = SEC_IA5StringTemplate;
		break;
	      case SEC_ASN1_OCTET_STRING:
		sub = SEC_OctetStringTemplate;
		break;
	      case SEC_ASN1_PRINTABLE_STRING:
		sub = SEC_PrintableStringTemplate;
		break;
	      case SEC_ASN1_T61_STRING:
		sub = SEC_T61StringTemplate;
		break;
	      case SEC_ASN1_UNIVERSAL_STRING:
		sub = SEC_UniversalStringTemplate;
		break;
	      case SEC_ASN1_UTC_TIME:
		sub = SEC_UTCTimeTemplate;
		break;
	      case SEC_ASN1_UTF8_STRING:
		sub = SEC_UTF8StringTemplate;
		break;
	      case SEC_ASN1_VISIBLE_STRING:
		sub = SEC_VisibleStringTemplate;
		break;
	      case SEC_ASN1_SKIP:
		sub = SEC_SkipTemplate;
		break;
	      default:		/* redundant given outer switch cases, but */
		PORT_Assert(0);	/* the compiler does not seem to know that, */
		sub = NULL;	/* so just do enough to quiet it. */
		break;
	    }

	    state->place = duringConstructedString;
	    state = sec_asn1d_push_state (state->top, sub, item, PR_TRUE);
	    if (state != NULL) {
		state->substring = PR_TRUE;	/* XXX propogate? */
		state = sec_asn1d_init_state_based_on_template (state);
	    }
	} else if (state->indefinite) {
	    /*
	     * An indefinite-length string *must* be constructed!
	     */
	    PORT_SetError (SEC_ERROR_BAD_DER);
	    state->top->status = decodeError;
	} else {
	    /*
	     * A non-zero-length simple string.
	     */
	    if (state->underlying_kind == SEC_ASN1_BIT_STRING)
		state->place = beforeBitString;
	    else
		state->place = duringLeaf;
	}
	break;

      default:
	/*
	 * We are allocating for a simple leaf item.
	 */
	if (state->contents_length) {
	    if (state->dest != NULL) {
		item = (SECItem *)(state->dest);
		item->len = 0;
		if (state->top->filter_only) {
		    item->data = NULL;
		} else {
		    item->data = (unsigned char*)
		                  sec_asn1d_zalloc (state->top->their_pool,
						   state->contents_length);
		    if (item->data == NULL) {
			state->top->status = decodeError;
			return;
		    }
		}
	    }
	    state->place = duringLeaf;
	} else {
	    /*
	     * An indefinite-length or zero-length item is not allowed.
	     * (All legal cases of such were handled above.)
	     */
	    PORT_SetError (SEC_ERROR_BAD_DER);
	    state->top->status = decodeError;
	}
    }
}


static void
sec_asn1d_free_child (sec_asn1d_state *state, PRBool error)
{
    if (state->child != NULL) {
	PORT_Assert (error || state->child->consumed == 0);
	PORT_Assert (state->our_mark != NULL);
	PORT_ArenaRelease (state->top->our_pool, state->our_mark);
	if (error && state->top->their_pool == NULL) {
	    /*
	     * XXX We need to free anything allocated.
	     */
	    PORT_Assert (0);
	}
	state->child = NULL;
	state->our_mark = NULL;
    } else {
	/*
	 * It is important that we do not leave a mark unreleased/unmarked.
	 * But I do not think we should ever have one set in this case, only
	 * if we had a child (handled above).  So check for that.  If this
	 * assertion should ever get hit, then we probably need to add code
	 * here to release back to our_mark (and then set our_mark to NULL).
	 */
	PORT_Assert (state->our_mark == NULL);
    }
    state->place = beforeEndOfContents;
}


static void
sec_asn1d_reuse_encoding (sec_asn1d_state *state)
{
    sec_asn1d_state *child;
    unsigned long consumed;
    SECItem *item;
    void *dest;


    child = state->child;
    PORT_Assert (child != NULL);

    consumed = child->consumed;
    child->consumed = 0;

    item = (SECItem *)(state->dest);
    PORT_Assert (item != NULL);

    PORT_Assert (item->len == consumed);

    /*
     * Free any grandchild.
     */
    sec_asn1d_free_child (child, PR_FALSE);

    /*
     * Notify after the SAVE field.
     */
    sec_asn1d_notify_after (state->top, state->dest, state->depth);

    /*
     * Adjust to get new dest and move forward.
     */
    dest = (char *)state->dest - state->theTemplate->offset;
    state->theTemplate++;
    child->dest = (char *)dest + state->theTemplate->offset;
    child->theTemplate = state->theTemplate;

    /*
     * Notify before the "real" field.
     */
    PORT_Assert (state->depth == child->depth);
    sec_asn1d_notify_before (state->top, child->dest, child->depth);

    /*
     * This will tell DecoderUpdate to return when it is done.
     */
    state->place = afterSaveEncoding;

    /*
     * We already have a child; "push" it by making it current.
     */
    state->top->current = child;

    /*
     * And initialize it so it is ready to parse.
     */
    (void) sec_asn1d_init_state_based_on_template(child);

    /*
     * Now parse that out of our data.
     */
    if (SEC_ASN1DecoderUpdate (state->top,
			       (char *) item->data, item->len) != SECSuccess)
	return;

    PORT_Assert (state->top->current == state);
    PORT_Assert (state->child == child);

    /*
     * That should have consumed what we consumed before.
     */
    PORT_Assert (consumed == child->consumed);
    child->consumed = 0;

    /*
     * Done.
     */
    state->consumed += consumed;
    child->place = notInUse;
    state->place = afterEndOfContents;
}


static unsigned long
sec_asn1d_parse_leaf (sec_asn1d_state *state,
		      const char *buf, unsigned long len)
{
    SECItem *item;

    if (len == 0) {
	state->top->status = needBytes;
	return 0;
    }

    if (state->pending < len)
	len = state->pending;

    item = (SECItem *)(state->dest);
    if (item != NULL && item->data != NULL) {
	PORT_Memcpy (item->data + item->len, buf, len);
	item->len += len;
    }
    state->pending -= len;
    if (state->pending == 0)
	state->place = beforeEndOfContents;

    return len;
}


static unsigned long
sec_asn1d_parse_bit_string (sec_asn1d_state *state,
			    const char *buf, unsigned long len)
{
    unsigned char byte;

    PORT_Assert (state->pending > 0);
    PORT_Assert (state->place == beforeBitString);

    if (len == 0) {
	state->top->status = needBytes;
	return 0;
    }

    byte = (unsigned char) *buf;
    if (byte > 7) {
	PORT_SetError (SEC_ERROR_BAD_DER);
	state->top->status = decodeError;
	return 0;
    }

    state->bit_string_unused_bits = byte;
    state->place = duringBitString;
    state->pending -= 1;

    return 1;
}


static unsigned long
sec_asn1d_parse_more_bit_string (sec_asn1d_state *state,
				 const char *buf, unsigned long len)
{
    PORT_Assert (state->pending > 0);
    PORT_Assert (state->place == duringBitString);

    len = sec_asn1d_parse_leaf (state, buf, len);
    if (state->place == beforeEndOfContents && state->dest != NULL) {
	SECItem *item;

	item = (SECItem *)(state->dest);
	if (item->len)
	    item->len = (item->len << 3) - state->bit_string_unused_bits;
    }

    return len;
}


/*
 * XXX All callers should be looking at return value to detect
 * out-of-memory errors (and stop!).
 */
static struct subitem *
sec_asn1d_add_to_subitems (sec_asn1d_state *state,
			   const void *data, unsigned long len,
			   PRBool copy_data)
{
    struct subitem *thing;

    thing = (struct subitem*)sec_asn1d_zalloc (state->top->our_pool,
				sizeof (struct subitem));
    if (thing == NULL) {
	state->top->status = decodeError;
	return NULL;
    }

    if (copy_data) {
	void *copy;
	copy = sec_asn1d_alloc (state->top->our_pool, len);
	if (copy == NULL) {
	    state->top->status = decodeError;
	    return NULL;
	}
	PORT_Memcpy (copy, data, len);
	thing->data = copy;
    } else {
	thing->data = data;
    }
    thing->len = len;
    thing->next = NULL;

    if (state->subitems_head == NULL) {
	PORT_Assert (state->subitems_tail == NULL);
	state->subitems_head = state->subitems_tail = thing;
    } else {
	state->subitems_tail->next = thing;
	state->subitems_tail = thing;
    }

    return thing;
}


static void
sec_asn1d_record_any_header (sec_asn1d_state *state,
			     const char *buf,
			     unsigned long len)