linux

dhcp-3.1.0.tar.gz。DHCP源代码

#!/bin/bash
# dhclient-script for Linux. Dan Halbert, March, 1997.
# Updated for Linux 2.[12] by Brian J. Murrell, January 1999.
# No guarantees about this. I'm a novice at the details of Linux
# networking.

# Notes:

# 0. This script is based on the netbsd script supplied with dhcp-970306.

# 1. ifconfig down apparently deletes all relevant routes and flushes
# the arp cache, so this doesn't need to be done explicitly.

# 2. The alias address handling here has not been tested AT ALL.
# I'm just going by the doc of modern Linux ip aliasing, which uses
# notations like eth0:0, eth0:1, for each alias.

# 3. I have to calculate the network address, and calculate the broadcast
# address if it is not supplied. This might be much more easily done
# by the dhclient C code, and passed on.

# 4. TIMEOUT not tested. ping has a flag I don't know, and I'm suspicious
# of the $1 in its args.

make_resolv_conf() {
  if [ x"$new_domain_name_servers" != x ]; then
    cat /dev/null > /etc/resolv.conf.dhclient
    chmod 644 /etc/resolv.conf.dhclient
    if [ x"$new_domain_search" != x ]; then
      echo search $new_domain_search >> /etc/resolv.conf.dhclient
    elif [ x"$new_domain_name" != x ]; then
      # Note that the DHCP 'Domain Name Option' is really just a domain
      # name, and that this practice of using the domain name option as
      # a search path is both nonstandard and deprecated.
      echo search $new_domain_name >> /etc/resolv.conf.dhclient
    fi
    for nameserver in $new_domain_name_servers; do
      echo nameserver $nameserver >>/etc/resolv.conf.dhclient
    done

    mv /etc/resolv.conf.dhclient /etc/resolv.conf
  fi
}

# Must be used on exit.   Invokes the local dhcp client exit hooks, if any.
exit_with_hooks() {
  exit_status=$1
  if [ -f /etc/dhclient-exit-hooks ]; then
    . /etc/dhclient-exit-hooks
  fi
# probably should do something with exit status of the local script
  exit $exit_status
}

# Invoke the local dhcp client enter hooks, if they exist.
if [ -f /etc/dhclient-enter-hooks ]; then
  exit_status=0
  . /etc/dhclient-enter-hooks
  # allow the local script to abort processing of this state
  # local script must set exit_status variable to nonzero.
  if [ $exit_status -ne 0 ]; then
    exit $exit_status
  fi
fi

release=`uname -r`
release=`expr $release : '\(.*\)\..*'`
relminor=`echo $release |sed -e 's/[0-9]*\.\([0-9][0-9]*\)\(\..*\)*$/\1/'`
relmajor=`echo $release |sed -e 's/\([0-9][0-9]*\)\..*$/\1/'`

if [ x$new_broadcast_address != x ]; then
  new_broadcast_arg="broadcast $new_broadcast_address"
fi
if [ x$old_broadcast_address != x ]; then
  old_broadcast_arg="broadcast $old_broadcast_address"
fi
if [ x$new_subnet_mask != x ]; then
  new_subnet_arg="netmask $new_subnet_mask"
fi
if [ x$old_subnet_mask != x ]; then
  old_subnet_arg="netmask $old_subnet_mask"
fi
if [ x$alias_subnet_mask != x ]; then
  alias_subnet_arg="netmask $alias_subnet_mask"
fi

if [ x$reason = xMEDIUM ]; then
  # Linux doesn't do mediums (ok, ok, media).
  exit_with_hooks 0
fi

if [ x$reason = xPREINIT ]; then
  if [ x$alias_ip_address != x ]; then
    # Bring down alias interface. Its routes will disappear too.
    ifconfig $interface:0- inet 0
  fi
  if [ $relmajor -lt 2 ] || ( [ $relmajor -eq 2 ] && [ $relminor -eq 0 ] )
   then
    ifconfig $interface inet 0.0.0.0 netmask 0.0.0.0 \
		broadcast 255.255.255.255 up
    # Add route to make broadcast work. Do not omit netmask.
    route add default dev $interface netmask 0.0.0.0
  else
    ifconfig $interface 0 up
  fi

  # We need to give the kernel some time to get the interface up.
  sleep 1

  exit_with_hooks 0
fi

if [ x$reason = xARPCHECK ] || [ x$reason = xARPSEND ]; then
  exit_with_hooks 0
fi
  
if [ x$reason = xBOUND ] || [ x$reason = xRENEW ] || \
   [ x$reason = xREBIND ] || [ x$reason = xREBOOT ]; then
  current_hostname=`hostname`
  if [ x$current_hostname = x ] || \
     [ x$current_hostname = x$old_host_name ]; then
    if [ x$current_hostname = x ] || \
       [ x$new_host_name != x$old_host_name ]; then
      hostname $new_host_name
    fi
  fi
    
  if [ x$old_ip_address != x ] && [ x$alias_ip_address != x ] && \
		[ x$alias_ip_address != x$old_ip_address ]; then
    # Possible new alias. Remove old alias.
    ifconfig $interface:0- inet 0
  fi
  if [ x$old_ip_address != x ] && [ x$old_ip_address != x$new_ip_address ]; then
    # IP address changed. Bringing down the interface will delete all routes,
    # and clear the ARP cache.
    ifconfig $interface inet 0 down

  fi
  if [ x$old_ip_address = x ] || [ x$old_ip_address != x$new_ip_address ] || \
     [ x$reason = xBOUND ] || [ x$reason = xREBOOT ]; then

    ifconfig $interface inet $new_ip_address $new_subnet_arg \
							$new_broadcast_arg
    # Add a network route to the computed network address.
    if [ $relmajor -lt 2 ] || \
		( [ $relmajor -eq 2 ] && [ $relminor -eq 0 ] ); then
      route add -net $new_network_number $new_subnet_arg dev $interface
    fi
    for router in $new_routers; do
      route add default gw $router
    done
  fi
  if [ x$new_ip_address != x$alias_ip_address ] && [ x$alias_ip_address != x ];
   then
    ifconfig $interface:0- inet 0
    ifconfig $interface:0 inet $alias_ip_address $alias_subnet_arg
    route add -host $alias_ip_address $interface:0
  fi
  make_resolv_conf
  exit_with_hooks 0
fi

if [ x$reason = xEXPIRE ] || [ x$reason = xFAIL ] || [ x$reason = xRELEASE ] \
   || [ x$reason = xSTOP ]; then
  if [ x$alias_ip_address != x ]; then
    # Turn off alias interface.
    ifconfig $interface:0- inet 0
  fi
  if [ x$old_ip_address != x ]; then
    # Shut down interface, which will delete routes and clear arp cache.
    ifconfig $interface inet 0 down
  fi
  if [ x$alias_ip_address != x ]; then
    ifconfig $interface:0 inet $alias_ip_address $alias_subnet_arg
    route add -host $alias_ip_address $interface:0
  fi
  exit_with_hooks 0
fi

if [ x$reason = xTIMEOUT ]; then
  if [ x$alias_ip_address != x ]; then
    ifconfig $interface:0- inet 0
  fi
  ifconfig $interface inet $new_ip_address $new_subnet_arg \
					$new_broadcast_arg
  set $new_routers
  ############## what is -w in ping?
  if ping -q -c 1 $1; then
    if [ x$new_ip_address != x$alias_ip_address ] && \
			[ x$alias_ip_address != x ]; then
      ifconfig $interface:0 inet $alias_ip_address $alias_subnet_arg
      route add -host $alias_ip_address dev $interface:0
    fi
    if [ $relmajor -lt 2 ] || \
		( [ $relmajor -eq 2 ] && [ $relminor -eq 0 ] ); then
      route add -net $new_network_number
    fi
    for router in $new_routers; do
      route add default gw $router
    done
    make_resolv_conf
    exit_with_hooks 0
  fi
  ifconfig $interface inet 0 down
  exit_with_hooks 1
fi

exit_with_hooks 0