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

	    dest = state->dest;
	    if (encode_kind & SEC_ASN1_INLINE) {
		/* check that there are no extraneous bits */
		PORT_Assert (encode_kind == SEC_ASN1_INLINE && !optional);
		state->place = afterInline;
	    } else {
		state->place = afterImplicit;
	    }
	}

	state->optional = optional;
	subt = SEC_ASN1GetSubtemplate (state->theTemplate, state->dest, PR_FALSE);
	state = sec_asn1d_push_state (state->top, subt, dest, PR_FALSE);
	if (state == NULL)
	    return NULL;

	state->allocate = child_allocate;

	if (universal) {
	    state = sec_asn1d_init_state_based_on_template (state);
	    if (state != NULL) {
		/*
		 * If this field is optional, we need to record that on
		 * the pushed child so it won't fail if the field isn't
		 * found.  I can't think of a way that this new state
		 * could already have optional set (which we would wipe
		 * out below if our local optional is not set) -- but
		 * just to be sure, assert that it isn't set.
		 */
		PORT_Assert (!state->optional);
		state->optional = optional;
	    }
	    return state;
	}

	under_kind = state->theTemplate->kind;
	under_kind &= ~SEC_ASN1_MAY_STREAM;
    } else if (explicit) {
	/*
	 * For explicit, we only need to match the encoding tag next,
	 * then we will push another state to handle the entire inner
	 * part.  In this case, there is no underlying kind which plays
	 * any part in the determination of the outer, explicit tag.
	 * So we just set under_kind to 0, which is not a valid tag,
	 * and the rest of the tag matching stuff should be okay.
	 */
	under_kind = 0;
    } else {
	/*
	 * Nothing special; the underlying kind and the given encoding
	 * information are the same.
	 */
	under_kind = encode_kind;
    }

    /* XXX is this the right set of bits to test here? */
    PORT_Assert ((under_kind & (SEC_ASN1_EXPLICIT | SEC_ASN1_OPTIONAL
				| SEC_ASN1_DYNAMIC | SEC_ASN1_MAY_STREAM
				| SEC_ASN1_INLINE | SEC_ASN1_POINTER)) == 0);

    if (encode_kind & (SEC_ASN1_ANY | SEC_ASN1_SKIP)) {
	PORT_Assert (encode_kind == under_kind);
	if (encode_kind & SEC_ASN1_SKIP) {
	    PORT_Assert (!optional);
	    PORT_Assert (encode_kind == SEC_ASN1_SKIP);
	    state->dest = NULL;
	}
	check_tag_mask = 0;
	expect_tag_modifiers = 0;
	expect_tag_number = 0;
    } else {
	check_tag_mask = SEC_ASN1_TAG_MASK;
	expect_tag_modifiers = encode_kind & SEC_ASN1_TAG_MASK
				& ~SEC_ASN1_TAGNUM_MASK;
	/*
	 * XXX This assumes only single-octet identifiers.  To handle
	 * the HIGH TAG form we would need to do some more work, especially
	 * in how to specify them in the template, because right now we
	 * do not provide a way to specify more *tag* bits in encode_kind.
	 */
	expect_tag_number = encode_kind & SEC_ASN1_TAGNUM_MASK;

	switch (under_kind & SEC_ASN1_TAGNUM_MASK) {
	  case SEC_ASN1_SET:
	    /*
	     * XXX A plain old SET (as opposed to a SET OF) is not implemented.
	     * If it ever is, remove this assert...
	     */
	    PORT_Assert ((under_kind & SEC_ASN1_GROUP) != 0);
	    /* fallthru */
	  case SEC_ASN1_SEQUENCE:
	    expect_tag_modifiers |= SEC_ASN1_CONSTRUCTED;
	    break;
	  case SEC_ASN1_BIT_STRING:
	  case SEC_ASN1_BMP_STRING:
	  case SEC_ASN1_GENERALIZED_TIME:
	  case SEC_ASN1_IA5_STRING:
	  case SEC_ASN1_OCTET_STRING:
	  case SEC_ASN1_PRINTABLE_STRING:
	  case SEC_ASN1_T61_STRING:
	  case SEC_ASN1_UNIVERSAL_STRING:
	  case SEC_ASN1_UTC_TIME:
	  case SEC_ASN1_UTF8_STRING:
	  case SEC_ASN1_VISIBLE_STRING:
	    check_tag_mask &= ~SEC_ASN1_CONSTRUCTED;
	    break;
	}
    }

    state->check_tag_mask = check_tag_mask;
    state->expect_tag_modifiers = expect_tag_modifiers;
    state->expect_tag_number = expect_tag_number;
    state->underlying_kind = under_kind;
    state->explicit = explicit;
    state->optional = optional;

    sec_asn1d_scrub_state (state);

    return state;
}


static unsigned long
sec_asn1d_parse_identifier (sec_asn1d_state *state,
			    const char *buf, unsigned long len)
{
    unsigned char byte;
    unsigned char tag_number;

    PORT_Assert (state->place == beforeIdentifier);

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

    byte = (unsigned char) *buf;
    tag_number = byte & SEC_ASN1_TAGNUM_MASK;

    if (IS_HIGH_TAG_NUMBER (tag_number)) {
	state->place = duringIdentifier;
	state->found_tag_number = 0;
	/*
	 * Actually, we have no idea how many bytes are pending, but we
	 * do know that it is at least 1.  That is all we know; we have
	 * to look at each byte to know if there is another, etc.
	 */
	state->pending = 1;
    } else {
	if (byte == 0 && state->parent != NULL &&
		    (state->parent->indefinite ||
			(
			    (state->parent->place == afterImplicit ||
			     state->parent->place == afterPointer)
			    && state->parent->parent != NULL && state->parent->parent->indefinite
			)
		    )
	    ) {
	    /*
	     * Our parent has indefinite-length encoding, and the
	     * entire tag found is 0, so it seems that we have hit the
	     * end-of-contents octets.  To handle this, we just change
	     * our state to that which expects to get the bytes of the
	     * end-of-contents octets and let that code re-read this byte
	     * so that our categorization of field types is correct.
	     * After that, our parent will then deal with everything else.
	     */
	    state->place = duringEndOfContents;
	    state->pending = 2;
	    state->found_tag_number = 0;
	    state->found_tag_modifiers = 0;
	    /*
	     * We might be an optional field that is, as we now find out,
	     * missing.  Give our parent a clue that this happened.
	     */
	    if (state->optional)
		state->missing = PR_TRUE;
	    return 0;
	}
	state->place = afterIdentifier;
	state->found_tag_number = tag_number;
    }
    state->found_tag_modifiers = byte & ~SEC_ASN1_TAGNUM_MASK;

    return 1;
}


static unsigned long
sec_asn1d_parse_more_identifier (sec_asn1d_state *state,
				 const char *buf, unsigned long len)
{
    unsigned char byte;
    int count;

    PORT_Assert (state->pending == 1);
    PORT_Assert (state->place == duringIdentifier);

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

    count = 0;

    while (len && state->pending) {
	if (HIGH_BITS (state->found_tag_number, TAG_NUMBER_BITS) != 0) {
	    /*
	     * The given high tag number overflows our container;
	     * just give up.  This is not likely to *ever* happen.
	     */
	    PORT_SetError (SEC_ERROR_BAD_DER);
	    state->top->status = decodeError;
	    return 0;
	}

	state->found_tag_number <<= TAG_NUMBER_BITS;

	byte = (unsigned char) buf[count++];
	state->found_tag_number |= (byte & TAG_NUMBER_MASK);

	len--;
	if (LAST_TAG_NUMBER_BYTE (byte))
	    state->pending = 0;
    }

    if (state->pending == 0)
	state->place = afterIdentifier;

    return count;
}


static void
sec_asn1d_confirm_identifier (sec_asn1d_state *state)
{
    PRBool match;

    PORT_Assert (state->place == afterIdentifier);

    match = (PRBool)(((state->found_tag_modifiers & state->check_tag_mask)
	     == state->expect_tag_modifiers)
	    && ((state->found_tag_number & state->check_tag_mask)
		== state->expect_tag_number));
    if (match) {
	state->place = beforeLength;
    } else {
	if (state->optional) {
	    state->missing = PR_TRUE;
	    state->place = afterEndOfContents;
	} else {
	    PORT_SetError (SEC_ERROR_BAD_DER);
	    state->top->status = decodeError;
	}
    }
}


static unsigned long
sec_asn1d_parse_length (sec_asn1d_state *state,
			const char *buf, unsigned long len)
{
    unsigned char byte;

    PORT_Assert (state->place == beforeLength);

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

    /*
     * The default/likely outcome.  It may get adjusted below.
     */
    state->place = afterLength;

    byte = (unsigned char) *buf;

    if (LENGTH_IS_SHORT_FORM (byte)) {
	state->contents_length = byte;
    } else {
	state->contents_length = 0;
	state->pending = LONG_FORM_LENGTH (byte);
	if (state->pending == 0) {
	    state->indefinite = PR_TRUE;
	} else {
	    state->place = duringLength;
	}
    }

    return 1;
}


static unsigned long
sec_asn1d_parse_more_length (sec_asn1d_state *state,
			     const char *buf, unsigned long len)
{
    int count;

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

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

    count = 0;

    while (len && state->pending) {
	if (HIGH_BITS (state->contents_length, 8) != 0) {
	    /*
	     * The given full content length overflows our container;
	     * just give up.
	     */
	    PORT_SetError (SEC_ERROR_BAD_DER);
	    state->top->status = decodeError;
	    return 0;
	}

	state->contents_length <<= 8;
	state->contents_length |= (unsigned char) buf[count++];

	len--;
	state->pending--;
    }

    if (state->pending == 0)
	state->place = afterLength;

    return count;
}


static void
sec_asn1d_prepare_for_contents (sec_asn1d_state *state)
{
    SECItem *item;
    PRArenaPool *poolp;
    unsigned long alloc_len;


    /*
     * XXX I cannot decide if this allocation should exclude the case
     *     where state->endofcontents is true -- figure it out!
     */
    if (state->allocate) {
	void *dest;

	PORT_Assert (state->dest == NULL);
	/*
	 * We are handling a POINTER or a member of a GROUP, and need to
	 * allocate for the data structure.
	 */
	dest = sec_asn1d_zalloc (state->top->their_pool,
				 state->theTemplate->size);
	if (dest == NULL) {
	    state->top->status = decodeError;
	    return;
	}
	state->dest = (char *)dest + state->theTemplate->offset;

	/*
	 * For a member of a GROUP, our parent will later put the
	 * pointer wherever it belongs.  But for a POINTER, we need
	 * to record the destination now, in case notify or filter
	 * procs need access to it -- they cannot find it otherwise,
	 * until it is too late (for one-pass processing).
	 */
	if (state->parent->place == afterPointer) {
	    void **placep;

	    placep = state->parent->dest;
	    *placep = dest;
	}
    }

    /*
     * Remember, length may be indefinite here!  In that case,
     * both contents_length and pending will be zero.
     */
    state->pending = state->contents_length;

    /*
     * An EXPLICIT is nothing but an outer header, which we have
     * already parsed and accepted.  Now we need to do the inner
     * header and its contents.
     */
    if (state->explicit) {
	state->place = afterExplicit;
	state = sec_asn1d_push_state (state->top,
				      SEC_ASN1GetSubtemplate(state->theTemplate,
							     state->dest,
							     PR_FALSE),
				      state->dest, PR_TRUE);
	if (state != NULL)
	    state = sec_asn1d_init_state_based_on_template (state);
	return;
    }

    /*
     * For GROUP (SET OF, SEQUENCE OF), even if we know the length here
     * we cannot tell how many items we will end up with ... so push a
     * state that can keep track of "children" (the individual members
     * of the group; we will allocate as we go and put them all together
     * at the end.
     */
    if (state->underlying_kind & SEC_ASN1_GROUP) {
	/* XXX If this assertion holds (should be able to confirm it via
	 * inspection, too) then move this code into the switch statement
	 * below under cases SET_OF and SEQUENCE_OF; it will be cleaner.
	 */
	PORT_Assert (state->underlying_kind == SEC_ASN1_SET_OF
		     || state->underlying_kind == SEC_ASN1_SEQUENCE_OF);
	if (state->contents_length != 0 || state->indefinite) {
	    const SEC_ASN1Template *subt;

	    state->place = duringGroup;
	    subt = SEC_ASN1GetSubtemplate (state->theTemplate, state->dest,
					   PR_FALSE);
	    state = sec_asn1d_push_state (state->top, subt, NULL, PR_TRUE);
	    if (state != NULL) {
		if (!state->top->filter_only)
		    state->allocate = PR_TRUE;	/* XXX propogate this? */
		/*
		 * Do the "before" field notification for next in group.
		 */
		sec_asn1d_notify_before (state->top, state->dest, state->depth);
		state = sec_asn1d_init_state_based_on_template (state);
	    }
	} else {
	    /*
	     * A group of zero; we are done.
	     * XXX Should we store a NULL here?  Or set state to
	     * afterGroup and let that code do it?
	     */
	    state->place = afterEndOfContents;
	}
	return;
    }

    switch (state->underlying_kind) {
      case SEC_ASN1_SEQUENCE:
	/*
	 * We need to push a child to handle the individual fields.
	 */
	state->place = duringSequence;
	state = sec_asn1d_push_state (state->top, state->theTemplate + 1,
				      state->dest, PR_TRUE);
	if (state != NULL) {
	    /*
	     * Do the "before" field notification.
	     */
	    sec_asn1d_notify_before (state->top, state->dest, state->depth);
	    state = sec_asn1d_init_state_based_on_template (state);
	}
	break;

      case SEC_ASN1_SET:	/* XXX SET is not really implemented */
	/*
	 * XXX A plain SET requires special handling; scanning of a
	 * template to see where a field should go (because by definition,
	 * they are not in any particular order, and you have to look at
	 * each tag to disambiguate what the field is).  We may never
	 * implement this because in practice, it seems to be unused.
	 */
	PORT_Assert(0);
	state->top->status = decodeError;
	break;

      case SEC_ASN1_NULL:
	/*
	 * The NULL type, by definition, is "nothing", content length of zero.
	 * An indefinite-length encoding is not alloweed.
	 */
	if (state->contents_length || state->indefinite) {
	    state->top->status = decodeError;
	    break;
	}
	if (state->dest != NULL) {