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List:       openldap-bugs
Subject:    Re: Multi-byte tags not working in LBER  (ITS#502)
From:       Kurt () OpenLDAP ! org
Date:       2000-04-25 7:20:24
[Download RAW message or body]

get_tag is ifdef'ed away.  I, however, believe that ber_get_tag()
has similiar problems.  I've committed a simple fix to devel and
will backport to 1.2 before next release.

	Kurt

At 01:45 PM 4/17/00 GMT, peter@cogno.com wrote:
>Full_Name: Peter Helfer
>Version: 1.2.9
>OS: Solaris
>URL: 
>Submission from: (NULL) (192.75.88.40)
>
>
>In libraries/liblber/io.c, function get_tag, if tag is 'i' bytes long
>and i > 1, then it is read into the leftmost i bytes of unsigned long tag.
>Then,
>
>    /* want leading, not trailing 0's */
>    return( tag >> (sizeof(long) - i - 1) );
>
>This doesn't work, because 
>    (a) rhs of >> specifies bits, not bytes
>    (b) >> shifts from msb to lsb, not from left to right in memory
>    (c) >> may fill either with 1s or 0s if msb is 1 (architecture dependent)
>    (d) the result needs to be converted to host byte order
>
>What's needed is something like:
>
>/* shift the bytes to the right */
>if (i < sizeof(long)) {
>    char *dest = (char *) &tag + sizeof(long) - 1;
>    char *src  = (char *) &tag + i - 1;
>
>    while (src >= (char *) &tag) {
>        *dest-- = *src--;
>    }
>    while (dest >= (char *) &tag) {
>        *dest-- = 0;
>    }
>}
>
>/* convert from network to host byte-order */
>tag = ntohl(tag);
>
>
>
>

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