#!/bin/bash
# Rebuild initial ramdisk with full network drivers,
# start DHCP and TFTP server in order to provide PXE service
#
# Author: Tomas M <www.slax.org>

LIVE=/run/initramfs
FTPROOT=/var/state/dnsmasq/root

# find out our own IP address. If more interfaces are available, use the first one
IP="$(hostname -I | cut -d " " -f 1)"
GW=$(ip route show | grep default | grep -o "via.*" | head -n 1 | cut -d " " -f 2)

# if no IP is assigned to this computer, setup private address randomly
if [ "$IP" = "" ]; then
   killall dhclient 2>/dev/null
   IP="10."$(($RANDOM/130+1))"."$(($RANDOM/130+1))".1"
   ifconfig $(ls -1 /sys/class/net | egrep -v '^lo$' | sort | head -n 1) $IP netmask 255.255.255.0
fi

# if gateway is not recognized, lets make our IP a gateway and enable forwarding
if [ "$GW" = "" ]; then
   GW="$IP"
   echo 1 > /proc/sys/net/ipv4/conf/all/forwarding
   echo 1 > /proc/sys/net/ipv6/conf/all/forwarding
fi

echo Starting PXE server on $IP ...

# calculate C class range
RANGE=$(echo $IP | cut -d "." -f 1-3)

# make sure dnsmasq can be started
killall dnsmasq 2>/dev/null
killall busybox 2>/dev/null
rm -Rf $FTPROOT 2>/dev/null
mkdir -p $FTPROOT/{pxelinux.cfg,tmp}/

# create root filesystem for ftfp
cd $LIVE
( find . -print | grep -v "memory"
  cd /
  find /lib/modules/$(uname -r)/kernel/drivers/net | grep -v wireless
) | cpio -pvd $FTPROOT/tmp 2>/dev/null

cp /lib/modules/$(uname -r)/modules.* $FTPROOT/tmp/lib/modules/$(uname -r)
depmod -b $FTPROOT/tmp
rm $FTPROOT/tmp/lib/initramfs_escaped

# pack root in initramfs
cd $FTPROOT/tmp
find . -print | cpio -o -H newc 2>/dev/null | gzip -f --fast >../initrfs.img
cd ..
rm -Rf tmp

# link files here since copying is not necessary
ln -s $(find $LIVE/memory/{data,iso,toram} 2>/dev/null | grep vmlinuz | head -n 1) $FTPROOT/vmlinuz
ln -s $(find $LIVE/memory/{data,iso,toram} 2>/dev/null | grep pxelinux.0 | head -n 1) $FTPROOT/pxelinux.0
ln -s $(find $LIVE/memory/{data,iso,toram} 2>/dev/null | grep ldlinux.c32 | head -n 1) $FTPROOT/ldlinux.c32

find $LIVE/memory/{data,iso,toram} 2>/dev/null | egrep "[.]sb\$" | sort -n | while read LINE; do
   BAS="$(basename "$LINE")"
   ln -s $LINE "$FTPROOT/$BAS"
   echo $BAS >> "$FTPROOT/PXEFILELIST"
done

echo "This is <a href=http://www.slax.org/>Slax</a> PXE data server. PXE clients will download <a href=PXEFILELIST>file list</a>" > "$FTPROOT/index.html"

# default pxelinux configuration. Keep xmode selection for clients the same like for the server
echo "
PROMPT 0
DEFAULT slax
LABEL slax
KERNEL /vmlinuz
IPAPPEND 1
APPEND initrd=/initrfs.img load_ramdisk=1 prompt_ramdisk=0 rw printk.time=0 $(cat /proc/cmdline | egrep -o 'slax.flags=[^ ]+' | sed -r 's:[,=]pxe::' | sed -r 's:[,=]toram::')
" > $FTPROOT/pxelinux.cfg/default

# start the DHCP server and TFTP server
dnsmasq --enable-tftp --tftp-root=/var/state/dnsmasq/root \
--dhcp-boot=pxelinux.0,"$IP",$IP \
--dhcp-option=3,$GW \
--dhcp-range=$RANGE.2,$RANGE.250,infinite --log-dhcp

# start HTTP server at port 7529 (that are the numbers you type on your phone to write 'slax')
busybox httpd -p 7529 -h /var/state/dnsmasq/root