#!/bin/bash
#
# Copyright (C) 2014 Robert Milasan <rmilasan@suse.com>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
# This script run manually by user, will generate a persistent rule for
# a given network interface to rename it to new interface name.
#

prj=${0##*/}

log_info()
{
  local msg="$1"
  echo "$prj: $msg"
}

log_error()
{
 local msg=$1
 echo "$prj: $msg" >&2
}

usage()
{
  set -f
  cat << EOF
$prj: udev persistent rule generator

Usage: $prj [OPTION] ...

       -h                show this help
       -m                generate the persistent rule based on interface MAC address
       -p                generate the persistent rule based on interface PCI slot
       -v                be verbose
       -c <INTERFACE>    current interface name (ex: "ip a s")
       -n <INTERFACE>    new interface name (ex: net0)
       -o <FILE>         where to write the new generate rule (default: /dev/stdout)
                         prefered location is /etc/udev/rules.d/70-persistent-net.rules

Example:
       $prj -m -c enp0s4 -n net0 -o /etc/udev/rules.d/70-persistent-net.rules
    or
       $prj -p -c wlp3s0 -n wlan0 -o /etc/udev/rules.d/50-mynet.rules

EOF
}

display_note()
{
  cat <<'EOF'

NOTE: Using the generate persistent rule might mean you will need to do extra
work to ensure that it will work accordingly.     This mean, regenerating the
initramfs/initrd image and/or using 'net.ifnames=0' option at boot time.

In openSUSE/SUSE, the user will need to regenerate the initramfs/initrd image,
but usually there is no need for 'net.ifnames=0' option if the persistent rule
is available in initramfs/initrd image.

EOF
}

get_pci()
{
  local path=$1
  local pci=""

  if [ -L "$path/device" ]; then
     local pci_link="$(readlink -f $path/device 2>/dev/null)"
     pci="$(basename $pci_link 2>/dev/null)"
  fi
  echo $pci
}

get_pci_id()
{
  local path=$1
  local pci_id=""

  if [ -r "$path/device/uevent" ]; then
     local _pci_id="$(cat $path/device/uevent|grep ^PCI_ID 2>/dev/null)"
     pci_id="${_pci_id#*=}"
  fi
  echo $pci_id
}

get_macaddr()
{
  local path=$1
  local macaddr=""

  if [ -r "$path/address" ]; then
     macaddr="$(cat $path/address 2>/dev/null)"
  fi
  echo $macaddr
}

get_type()
{
  local path=$1
  local dev_type=""
  
  if [ -r "$path/type" ]; then
     dev_type="$(cat $path/type 2>/dev/null)"
  fi
  echo $dev_type
}

get_dev_id()
{
  local path=$1
  local dev_id=""

  if [ -r "$path/dev_id" ]; then
     dev_id="$(cat $path/dev_id 2>/dev/null)"
  fi
  echo $dev_id
}

get_devtype()
{
  local path=$1
  local devtype=""
  if [ -r "$path/uevent" ]; then
     local _devtype="$(cat $path/uevent|grep ^DEVTYPE 2>/dev/null)"
     devtype="${_devtype#*=}"
  fi
  echo $devtype
}

get_subsystem()
{
  local path=$1
  local subsystem=""

  if [ -L "$path/subsystem" ]; then
     local subsystem_link="$(readlink -f $path/subsystem 2>/dev/null)"
     subsystem="$(basename $subsystem_link 2>/dev/null)"
  fi
  echo $subsystem
}

get_driver()
{
  local path=$1
  local driver=""

  if [ -L "$path/device/driver" ]; then
     local driver_link="$(readlink -f $path/device/driver 2>/dev/null)"
     driver="$(basename $driver_link 2>/dev/null)"
  fi
  echo $driver
}

valid_mac()
{
  local macaddr=$1
  local valid_macaddr=""

  if [ -n "$macaddr" ]; then
     valid_macaddr="$(echo $macaddr | sed -n '/^\([0-9a-z][0-9a-z]:\)\{5\}[0-9a-z][0-9a-z]$/p')"
  fi
  echo $valid_macaddr
}

generate_comment()
{
  local pci_id=$1
  local driver=$2
  local output=$3
  
  if [ -z "$pci_id" ]; then
     log_error "\$pci_id empty."
     exit 1
  elif [ -z "$driver" ]; then
     log_error "\$driver empty."
     exit 1
  elif [ -z "$output" ]; then
     log_error "\$output empty."
     exit 1
  else
     echo "# PCI device $pci_id ($driver) with official udev name $interface renamed to unsupported $new_interface" >> $output
  fi
}

generate_rule()
{
  local _subsystem=$1
  local _mac=$2
  local _pci=$3
  local _dev_id=$4
  local _dev_type=$5
  local _kernel=$6
  local _interface=$7
  local output=$8

  if [ -z "$_subsystem" ]; then
     log_error "\$_subsystem empty."
     exit 1
  elif [ -z "$_dev_id" ]; then
     log_error "\$_dev_id empty."
     exit 1
  elif [ -z "$_dev_type" ]; then
     log_error "\$_dev_type empty."
     exit 1
  elif [ -z "$_kernel" ]; then
     log_error "\$_kernel empty."
     exit 1
  elif [ -z "$_interface" ]; then
     log_error "\$_interface empty."
     exit 1
  elif [ -z "$output" ]; then
     output="/dev/stdout"
  fi

  if [ "$_mac" != "none" ]; then
     echo "SUBSYSTEM==\"$_subsystem\", ACTION==\"add\", DRIVERS==\"?*\", ATTR{address}==\"$_mac\", \
ATTR{dev_id}==\"$_dev_id\", ATTR{type}==\"$_dev_type\", KERNEL==\"$_kernel\", NAME=\"$_interface\"" >> ${output}
  elif [ "$_pci" != "none" ]; then
     echo "SUBSYSTEM==\"$_subsystem\", ACTION==\"add\", DRIVERS==\"?*\", KERNELS==\"$_pci\", \
ATTR{dev_id}==\"$_dev_id\", ATTR{type}==\"$_dev_type\", KERNEL==\"$_kernel\", NAME=\"$_interface\"" >> ${output}
  else
     log_error "MAC address or PCI slot information missing."
     exit 1
  fi
}

if [ $# -eq 0 ]; then
   usage
   log_error "missing option(s)."
   exit 1
fi

use_mac=0
use_pci=0
use_verbose=0

while getopts "hmpvc:n:o:" opt; do
  case "$opt" in
     h)
       usage; exit 0;;
     m)
       use_mac=1 ;;
     p)
       use_pci=1 ;;
     v)
       use_verbose=1 ;;
     c)
       ifcur="$OPTARG" ;;
     n)
       ifnew="$OPTARG" ;;
     o)
       output="$OPTARG" ;;
     \?)
       exit 1 ;;
  esac
done

if [[ "$use_mac" -eq 1 ]] && [[ "$use_pci" -eq 1 ]]; then
   log_error "generating a persistent rule can be done only using one of the option, -m or -p, not both."
   exit 1
fi

outfile=$output
if [ -z "$output" ]; then
   outfile=/dev/stdout
else
   dir="$(dirname $outfile 2>/dev/null)"
   tmpfile="$dir/.tmp_file"
   if [ -d "$dir" ]; then
      touch "$tmpfile" >/dev/null 2>&1
      if [ $? -ne 0 ]; then
         log_error "no write access for $outfile. make sure you have write permissions to $dir."
         exit 1
      fi
      rm -f "$tmpfile" >/dev/null 2>&1
   else
      log_error "$dir not a directory."
      exit 1
  fi
fi

interface=$ifcur
if [ -z "$interface" ]; then
   log_error "current interface must be specified."
   exit 1
elif [ "$interface" == "lo" ]; then
   log_error "loopback interface is not a valid interface."
   exit 1
fi
[ "$use_verbose" -eq 1 ] && echo "I: INTERFACE=$interface"

new_interface=$ifnew
if [ -z "$new_interface" ]; then
   log_error "new interface must be specified."
   exit 1
elif [ "$new_interface" == "lo" ]; then
   log_error "new interface cant be named loopback interface."
   exit 
fi
[ "$use_verbose" -eq 1 ] && echo "I: INTERFACE_NEW=$new_interface"

path="/sys/class/net/$interface"
if [ ! -d "$path" ]; then
   log_error "devpath $path not a directory."
   exit 1
fi
[ "$use_verbose" -eq 1 ] && echo "I: DEVPATH=$path"

devtype="$(get_devtype $path)"
if [ -n "$devtype" ]; then
   [ "$use_verbose" -eq 1 ] && echo "I: DEVTYPE=$devtype"
fi

subsystem="$(get_subsystem $path)"
if [ -z "$subsystem" ]; then
   log_error "unable to retrieve subsystem for interface $interface."
   exit 1
fi
[ "$use_verbose" -eq 1 ] && echo "I: SUBSYSTEM=$subsystem"

pci_id="$(get_pci_id $path)"
if [ -z "$pci_id" ]; then
   log_error "unable to retrieve PCI_ID for interface $interface."
   exit 1
fi
[ "$use_verbose" -eq 1 ] && echo "I: PCI_ID=$pci_id"

driver="$(get_driver $path)"
if [ -z "$driver" ]; then
   log_error "unable to retrieve driver for interface $interface."
   exit 1
fi
[ "$use_verbose" -eq 1 ] && echo "I: DRIVER=$driver"

if [ "$use_mac" -eq 1 ]; then
   macaddr="$(get_macaddr $path)"
   if [ -z "$macaddr" ]; then
      log_error "unable to retrieve MAC address for interface $interface."
      exit 1
   fi
   if [ "$(valid_mac $macaddr)" != "$macaddr" ]; then
      log_error "$macaddr invalid MAC address."
      exit 1
  fi
  [ "$use_verbose" -eq 1 ] && echo "I: MACADDR=$macaddr"
fi

if [ "$use_pci" -eq 1 ]; then
   pci="$(get_pci $path)"
   if [ -z "$pci" ]; then
      log_error "unable to retrieve PCI slot for interface $interface."
      exit 1
   fi
   [ "$use_verbose" -eq 1 ] && echo "I: KERNELS=$pci"
fi

dev_id="$(get_dev_id $path)"
if [ -z "$dev_id" ]; then
   log_error "unable to retrieve dev_id for interface $interface."
   exit 1
fi
[ "$use_verbose" -eq 1 ] && echo "I: DEV_ID=$dev_id"

dev_type="$(get_type $path)"
if [ -z "$dev_type" ]; then
   log_error "unable to retrieve dev_type for interface $interface."
   exit 1
fi
[ "$use_verbose" -eq 1 ] && echo "I: TYPE=$dev_type"

if [ "$devtype" == "wlan" ]; then
   kernel="wlan*"
else
   kernel="eth*"
fi

if [ -n "$output" ]; then
   echo "Persistent rule saved in "$outfile""
   echo
   generate_comment "$pci_id" "$driver" "$output"
fi

set -f
if [ "$use_mac" -eq 1 ]; then
   generate_rule "$subsystem" "$macaddr" "none" "$dev_id" "$dev_type" "$kernel" "$new_interface"
   if [ -n "$output" ]; then
      generate_rule "$subsystem" "$macaddr" "none" "$dev_id" "$dev_type" "$kernel" "$new_interface" "$output"
   fi
elif [ "$use_pci" -eq 1 ]; then
   generate_rule "$subsystem" "none" "$pci" "$dev_id" "$dev_type" "$kernel" "$new_interface"
   if [ -n "$output" ]; then
      generate_rule "$subsystem" "none" "$pci" "$dev_id" "$dev_type" "$kernel" "$new_interface" "$outfile"
   fi
fi

if [ -n "$output" ]; then
   display_note
fi

exit 0