Locating the Entry Store and Entry Fetch Examples

The plug-in function examples in this chapter can be found in install-path/examples/testentry.c.

The following example shows the entry store scrambling function used in this chapter. This function is called by Directory Server before writing an entry to the database.

Example 8–1 Entry Fetch Scrambler (testentry.c)

#include "slapi-plugin.h"

#ifdef _WIN32
typedef unsigned int uint;
__declspec(dllexport)
#endif
int
testentry_scramble(unsigned char ** entry, uint * len)
{
    uint i;

    (*len)++;
    *entry = slapi_ch_realloc(*entry, *len);
    /* Scramble using bitwise exclusive-or on each character.     */
    for (i = *len - 1; i > 0; i--) {
         (*entry)[i] = (*entry)[i - 1] ^ 0xaa;
    }
    (*entry)[0] = 0xaa;

    slapi_log_info_ex(
        SLAPI_LOG_INFO_AREA_PLUGIN,
        SLAPI_LOG_INFO_LEVEL_DEFAULT,
        SLAPI_LOG_NO_MSGID,
        SLAPI_LOG_NO_CONNID,
        SLAPI_LOG_NO_OPID,
        "testentry_scramble in test-entry plug-in",
        "Entry data scrambled.\n"
    );

    return 0;
}

The following example shows the entry fetch unscrambling function used in this chapter. The function is called by the server after reading an entry from the database.

Example 8–2 Entry Fetch UnScrambler (testentry.c)

#include "slapi-plugin.h"

#ifdef _WIN32
typedef unsigned int uint;
__declspec(dllexport)
#endif
int
testentry_unscramble(unsigned char ** entry, uint * len)
{
    uint i;

    /* Return now if the entry is not scrambled.                  */
    if (**entry != 0xaa) { return 0; }

    /* Unscramble using bitwise exclusive-or on each character.   */
    (*len)--;
    for (i = 0; i < *len; i++) {
        (*entry)[i] = (*entry)[i + 1] ^ 0xaa;
    }

    slapi_log_info_ex(
        SLAPI_LOG_INFO_AREA_PLUGIN,
        SLAPI_LOG_INFO_LEVEL_DEFAULT,
        SLAPI_LOG_NO_MSGID,
        SLAPI_LOG_NO_CONNID,
        SLAPI_LOG_NO_OPID,
        "testentry_unscramble in test-entry plug-in",
        "Entry data unscrambled.\n"
    );

    return 0;
}

Notice the symmetry between the two functions. The scrambling mask, 0xaa or 10101010 in binary, makes the transformation simple to understand but not secure. A secure encryption mechanism can be significantly more complicated.