modules.d/35network-legacy/dhcp-multi.sh

   1 #!/bin/sh
   2 # -*- mode: shell-script; indent-tabs-mode: nil; sh-basic-offset: 4; -*-
   3 # ex: ts=8 sw=4 sts=4 et filetype=sh
   4 #
   5 PATH=/usr/sbin:/usr/bin:/sbin:/bin
   6
   7 # File to start dhclient requests on different interfaces in parallel
   8
   9 . /lib/dracut-lib.sh
  10 . /lib/net-lib.sh
  11
  12 netif=$1
  13 do_vlan=$2
  14 arg=$3
  15
  16 # Run dhclient in parallel
  17 do_dhclient() {
  18     local _COUNT=0
  19     local _timeout
  20     local _DHCPRETRY
  21     _timeout=$(getarg rd.net.timeout.dhcp=)
  22     _DHCPRETRY=$(getargnum 1 1 1000000000 rd.net.dhcp.retry=)
  23
  24     if [ -n "$_timeout" ]; then
  25         if ! (dhclient --help 2>&1 | grep -q -F -- '--timeout' 2> /dev/null); then
  26             warn "rd.net.timeout.dhcp has no effect because dhclient does not implement the --timeout option"
  27             unset _timeout
  28         fi
  29     fi
  30
  31     while [ $_COUNT -lt "$_DHCPRETRY" ]; do
  32         info "Starting dhcp for interface $netif"
  33         dhclient "$arg" \
  34             ${_timeout:+--timeout "$_timeout"} \
  35             -q \
  36             -1 \
  37             -cf /etc/dhclient.conf \
  38             -pf /tmp/dhclient."$netif".pid \
  39             -lf /tmp/dhclient."$netif".lease \
  40             "$netif" &
  41         wait $! 2> /dev/null
  42
  43         # wait will return the return value of dhclient
  44         retv=$?
  45
  46         # dhclient and hence wait returned success, 0.
  47         if [ $retv -eq 0 ]; then
  48             return 0
  49         fi
  50
  51         # If dhclient exited before wait was called, or it was killed by
  52         # another thread for interface whose DHCP succeeded, then it will not
  53         # find the process with that pid and return error code 127. In that
  54         # case we need to check if /tmp/dhclient.$netif.lease exists. If it
  55         # does, it means dhclient finished executing before wait was called,
  56         # and it was successful (return 0). If /tmp/dhclient.$netif.lease
  57         # does not exist, then it means dhclient was killed by another thread
  58         # or it finished execution but failed dhcp on that interface.
  59
  60         if [ $retv -eq 127 ]; then
  61             read -r pid < /tmp/dhclient."$netif".pid
  62             info "PID $pid was not found by wait for $netif"
  63             if [ -e /tmp/dhclient."$netif".lease ]; then
  64                 info "PID $pid not found but DHCP successful on $netif"
  65                 return 0
  66             fi
  67         fi
  68
  69         _COUNT=$((_COUNT + 1))
  70         [ $_COUNT -lt "$_DHCPRETRY" ] && sleep 1
  71     done
  72     warn "dhcp for interface $netif failed"
  73     # nuke those files since we failed; we might retry dhcp again if it's e.g.
  74     # `ip=dhcp,dhcp6` and we check for the PID file earlier
  75     rm -f /tmp/dhclient."$netif".pid /tmp/dhclient."$netif".lease
  76     return 1
  77 }
  78
  79 do_dhclient
  80 ret=$?
  81
  82 # setup nameserver
  83 for s in "$dns1" "$dns2" $(getargs nameserver); do
  84     [ -n "$s" ] || continue
  85     echo nameserver "$s" >> /tmp/net."$netif".resolv.conf
  86 done
  87
  88 if [ $ret -eq 0 ]; then
  89     : > /tmp/net."${netif}".up
  90
  91     if [ -z "$do_vlan" ] && [ -e /sys/class/net/"${netif}"/address ]; then
  92         : > "/tmp/net.$(cat /sys/class/net/"${netif}"/address).up"
  93     fi
  94
  95     # Check if DHCP also suceeded on another interface before this one.
  96     # We will always use the first one on which DHCP succeeded, by using
  97     # a commom file $IFNETFILE, to synchronize between threads.
  98     # Consider the race condition in which multiple threads
  99     # corresponding to different interfaces may try to read $IFNETFILE
 100     # and find it does not exist; they may all end up thinking they are the
 101     # first to succeed (hence more than one thread may end up writing to
 102     # $IFNETFILE). To take care of this, instead of checking if $IFNETFILE
 103     # exists to determine if we are the first, we create a symbolic link
 104     # in $IFNETFILE, pointing to the interface name ($netif), thus storing
 105     # the interface name in the link pointer.
 106     # Creating a link will fail, if the link already exists, hence kernel
 107     # will take care of allowing only first thread to create link, which
 108     # takes care of the race condition for us. Subsequent threads will fail.
 109     # Also, the link points to the interface name, which will tell us which
 110     # interface succeeded.
 111
 112     if ln -s "$netif" "$IFNETFILE" 2> /dev/null; then
 113         intf=$(readlink "$IFNETFILE")
 114         if [ -e /tmp/dhclient."$intf".lease ]; then
 115             info "DHCP successful on interface $intf"
 116             # Kill all existing dhclient calls for other interfaces, since we
 117             # already got one successful interface
 118
 119             read -r npid < /tmp/dhclient."$netif".pid
 120             pidlist=$(pgrep dhclient)
 121             for pid in $pidlist; do
 122                 [ "$pid" -eq "$npid" ] && continue
 123                 kill -9 "$pid" > /dev/null 2>&1
 124             done
 125         else
 126             echo "ERROR! $IFNETFILE exists but /tmp/dhclient.$intf.lease does not exist!!!"
 127         fi
 128     else
 129         info "DHCP success on $netif, and also on $intf"
 130         exit 0
 131     fi
 132     exit $ret
 133 fi