Subject: Example of binary data
Author: SteveHB
In response to: Special Characters in Filter -- RFC-2254
Posted on: 08/17/2006 02:05:28 PM
(bin=\00\00\00\04)
This example shows a filter searching for the four-byte value 0x00000004, illustrating the use of the escaping mechanism to represent arbitrary data, including NUL characters.
>
> On 08/17/2006 01:50:27 PM
SteveHB wrote:
Special Characters defined in RFC 2254:
http://www.ietf.org/rfc/rfc2254.txt
If a value should contain any of the following characters
Character ASCII value
---------------------------
* 0x2a
( 0x28
) 0x29
\ 0x5c
NUL 0x00
the character must be encoded as the backslash '\' character (ASCII
0x5c) followed by the two hexadecimal digits representing the ASCII
value of the encoded character. The case of the two hexadecimal
digits is not significant.
This simple escaping mechanism eliminates filter-parsing ambiguities
and allows any filter that can be represented in LDAP to be
represented as a NUL-terminated string. Other characters besides the
ones listed above may be escaped using this mechanism, for example,
non-printing characters.
For example, the filter checking whether the "cn" attribute contained
a value with the character "*" anywhere in it would be represented as
"(cn=*\2a*)".
Note that although both the substring and present productions in the
grammar above can produce the "attr=*" construct, this construct is
used only to denote a presence filter.
References:
