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dhcp 4.1 r7

    1: #!/bin/bash
    2: #
    3: # dhclient-tz-exithook.sh
    4: # Version 1.01 elear
    5: #
    6: # Copyright (c) 2007, Cisco Systems, Inc.
    7: # All rights reserved.
    8: # 
    9: # Redistribution and use in source and binary forms, with or without
   10: # modification, are permitted provided that the following conditions
   11: # are met: 
   12: # 
   13: #    - Redistributions of source code must retain the above copyright
   14: #      notice, this list of conditions and the following disclaimer. 
   15: # 
   16: #    - Redistributions in binary form must reproduce the above copyright
   17: #      notice, this list of conditions and the following disclaimer in
   18: #      the documentation and/or other materials provided with the
   19: #      distribution.
   20: #
   21: #    - Neither the name of Cisco Systems, Inc. nor the names of its
   22: #      contributors may be used to endorse or promote products derived
   23: #      from this software without specific prior written permission.
   24: #    
   25: #    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   26: #    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   27: #    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   28: #    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   29: #    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
   30: #    INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   31: #    DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
   32: #    GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   33: #    INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
   34: #    WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
   35: #    NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   36: #    THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   37: #
   38: # the following script is used to set the timezone based on the new
   39: # dhcp timezone option defined currently in the IETF document
   40: # draft-ietf-dhc-timezone-option-04.txt.
   41: 
   42: # this code is intended for use with ISC's dhclient.  it is to be called
   43: # either as, or by, dhclient-exit-hooks
   44: #
   45: # As this is test code, in order for it to be called two changes
   46: # must be made to /etc/dhclient.conf.  First, dhclient.conf must be
   47: # aware of the tzName option.  The IANA has assigned tzName option
   48: # code 101.  You may need to add this to your configuration file.
   49: #
   50: #  option tzName code 101 = text;
   51: #
   52: # Next, add tzName to the list of options in the "request" statement.
   53: # For example:
   54: # 
   55: # request subnet-mask, broadcast-address, time-offset, routers,
   56: #         domain-name, domain-name-servers, host-name, tzName;
   57: #
   58: #
   59: # And of course make sure that your dhcp server is transmitting timezone
   60: # information for option 101.  For IOS this can be done as follows:
   61: # 
   62: #    option 101 ascii "Europe/Berlin"
   63: #
   64: 
   65: timefile=/etc/localtime
   66: oldfile=$timefile.old
   67: tmpfile=$timefile.$$
   68: 
   69: # function to clean up just in case we are interrupted or something
   70: # bad happens.
   71: restore_file () {
   72: 
   73:   if [ ! -f $timefile ]; then
   74:      $DEBUG mv $tmpfile $timefile
   75:   fi
   76:   $DEBUG rm $tmpfile
   77:   exit
   78: }
   79: 
   80: 
   81: #set DEBUG to "echo" to see what would happen.
   82: if [ x$DEBUG = x ]; then
   83:    DEBUG=
   84: fi
   85: 
   86: # if something has already gone wrong we're not doing a thing.
   87: if [ x$exit_status != x0 ]; then
   88:    exit $exit_status
   89: fi
   90: 
   91: 
   92: # if we don't have a new timezone, then we have nothing to change, so
   93: # goodbye.
   94: if [ x$new_tzName = x ]; then
   95:    exit 0
   96: fi
   97: 
   98: # if the timezone doesn't exist, goodbye.
   99: if [ ! -e $timefile ]; then
  100:    exit 0
  101: fi
  102: 
  103: # find zoneinfo. use the first one.
  104: ftz=0
  105: for a in /usr/share/zoneinfo /usr/lib/zoneinfo /var/share/zoneinfo /var/zoneinfo; do
  106:   if [ -d $a -a $ftz = 0 ]; then
  107:     zoneinfo=$a
  108:     ftz=1
  109:   fi
  110: done
  111: 
  112: # no zoneinfo found.  goodbye.
  113: if [ x$zoneinfo = x ]; then
  114:    exit 0
  115: fi
  116: 
  117: # timezone not found.  goodbye.
  118: if [ ! -f $zoneinfo/$new_tzName ]; then
  119:    exit 0
  120: fi
  121: 
  122: # if we're here we can actually do something useful.
  123: # first, link a copy of the existing timefile.
  124: 
  125: $DEBUG ln $timefile $tmpfile
  126: 
  127: if [ $? != 0 ]; then
  128:   echo "unable to create temporary file"
  129:   exit -1
  130: fi
  131: 
  132: # in case of interrupt, cleanup.
  133: trap restore_file SIGINT SIGSEGV SIGQUIT SIGTERM
  134: 
  135: # we destroy old backup files in this process.  if we cannot and the
  136: # file exists then something went wrong.
  137: if [ -e $oldfile ]; then
  138:   $DEBUG rm $oldfile
  139:   if [ $? != 0 ]; then
  140:      echo "$0: failed to remove $oldfile"
  141:      rm -f $tmpfile
  142:      exit -1
  143:   fi
  144: fi
  145: 
  146: # sensitive part happens here:
  147: #
  148: $DEBUG mv $timefile $oldfile
  149: 
  150:   if [ $? != 0 ]; then
  151:      echo "$0: failed to move old $timefile file out of the way"
  152:      rm $tmpfile
  153:      exit -1
  154:   fi
  155: 
  156: $DEBUG ln $zoneinfo/$new_tzName $timefile
  157: 
  158: # we don't complain just yet- a hard link could fail because
  159: # we're on two different file systems.  Go for a soft link.
  160: #
  161: 
  162: if [ $? != 0 ]; then
  163:   $DEBUG ln -s $zoneinfo/$new_tzName $timefile
  164: fi
  165: 
  166: if [ $? != 0 ]; then       # failed to softlink.  now we're getting nervous.
  167:   echo "$0: unable to establish new timezone.  Attempting to revert."
  168:   $DEBUG ln $tmpfile $timefile
  169: fi
  170: 
  171: 
  172: if [ $? != 0 ]; then       # we're absolutely hosed
  173:   echo "$0: unable to link or softlink timezone file, and unable to restore old file - giving up!"
  174:   exit -1
  175: fi
  176: 
  177: $DEBUG rm $tmpfile
  178: 
  179: exit $?