source: trunk/third/xntp/NOTES.y2kfixes @ 16192

Name of the Application: xntp

Version Number:  4.0.91

Download Size: 4541953 bytes

Downloaded from: http://www.eecis.udel.edu/~ntp/

Operating Systems Supported: many

Operating Systems Tested: unix

Testing

Dates tested (CPU clock set)

        1999-12-31
        2000-01-01
        2000-02-29

        Critical fragments of code tested with other dates by special
        algorithms.

Hardware Platform: Sun Sparc

OS: Solaris 2.6

Compiler: gcc

Version: 2.8.1

Repairs:  9

No. of files Repaired: 13


Compilation of Patches Required: yes

Results Description:

1)      Tested suspicious code.

2)      Repaired problem code and added documentation to ntp.h.

3)      Verified ntpd works on critical Y2K dates.


Comments:

1)      Errors were found in improper use of tm_year within struct tm,
        calculations that did not support year 2000 as a leap year
        (it truly is, despite any unchanged comments remaining in 
        the NTP source), and some incorrect date calculations, while
        not traditional Y2K errors, would break in the year 2000.

2)      include/ntpd.h
        Added some definitions and documentation about the right way
        of doing things.  Definitions used by most, if not all, of
        the Y2K repairs.

Cautions:

1)      Some of the Y2K repairs were to reference clock drivers that
        we did not have the local hardware to test.  While I believe
        the changes are sound, they really need to be tested.
        This includes:

                refclock_arc.c
                refclock_heath.c
                refclock_hpgps.c

        Also, parseutil/dcfd.c is another hardware dependent module that
        was repaired without live testing.

Non-Y2K Problems Observed:

1)      Inconsistent casts of variables containing time values may
        make expansion to 64 bit integer values in a portable manner
        difficult.

2)      libntp/caltontp.c:
        Has logic I believe will fail starting in year 2100 or so.
        Left unchanged/untested as it works well beyond basic NTP 2036 
        limit checked by check_y2k.c.
        If NTP is implemented on 64-bit machines, this should be fixed

3)      ntpd/refclock_acts.c:
        ACTS time format has changed somewhat since the code was written.
        In particular the '*' '#' character switch no longer occurs...
        only '*' is typed.

      NOTE: Author (falsely) stated Y2K is NOT a leap year when it 
      really is.

      TRUTH: ACTS will go beyond Y2K: it uses FourDigitYear % 100 values
      for year so year 2000 will revert to "00".


4)     ntpd/refclock_oncore.c
       Some very strange logic in manipulating year values:
       1122         instance->pp->year = buf[6]*256+buf[7];
       Multiply by 256????
 
    Response from PHK:
       The entire protocol is binary, the year is a 16 bit quantity 
       which according to the manual can have the range 1998-2018.