#!/bin/sh

#   Copyright (c) 2020, Geert Rolf
#
#   Permission is hereby granted, free of charge, to any person obtaining a
#   copy of this software and associated documentation files (the "Software"),
#   to deal in the Software without restriction, including without limitation
#   the rights to use, copy, modify, merge, publish, distribute, sublicense,
#   and/or sell copies of the Software, and to permit persons to whom the
#   Software is furnished to do so, subject to the following conditions:
#
#   The above copyright notice and this permission notice shall be included in
#   all copies or substantial portions of the Software.
#
#   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
#   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
#   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
#   GEERT ROLF BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
#   IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
#   CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
#

#	Test platforms:
#
#	Debian 10 (Buster)
#	Raspbian Buster
#	FreeBSD 12.1
#	OpenBSD 6.7
#	NetBSD 9.1

#		CHANGE HISTORY
#	2021/4/8	avoid setting PATH in scripts for root
#	2021/5/31	whereis used without -b in OpenBSD and NetBSD
#			Corrected: bridge create and fwdelay done twice for NetBSD
#			FreeBSD: tapX opened by userland program not by ifconfig
#	2021/11/17	check for existance of br0 done too lousy. Done better.
#

# uncomment next line if you need more than one tap = run multiple SIMHs...
#OPSMODE="expert"
# ... by editting the saved params file followed by rerun of this script

OS=`uname -s`
case $OS in
 "FreeBSD" | "OpenBSD" | "NetBSD")
	# List of Utils
	LOU="ifconfig brconfig sysctl chown netstat"

	# set $util to path of util for all in $LOU
	for U in $LOU
	do
		# whereis -b in only FreeBSD as in Linux
		if test $OS = "FreeBSD"
		then
			eval ${U}="`whereis -b $U |
				awk '{ if($2 != "")
					print $2;
				else
					print "void";
				}'`"
		else
			eval ${U}="`whereis $U |
				awk '{ if($1 != "")
					print $1;
				else
					print "void";
				}'`"
		fi
	done

	# make list of all interfaces ignoring lo
	AVL_IF=`$ifconfig -a |
		grep -v '^[ 	]' |
		awk -F: '{ print $1 }' |
		grep -v 'lo' |
		sed '1,$s/^ //'`

	## echo $AVL_IF

	# found bridge0 in active interfaces?
	L=`echo $AVL_IF | grep bridge0 | wc -l`
	if test $L -ne 0
	then
		echo "$0: bridge0 already configured."
		echo "-- if you configured bridge0 statically don't use this script"
		echo "-- otherwise if you do not want permanent settings"
		echo "-- and want bridge0 configured differently reboot first"
		exit 1
	fi

	;;
 "Linux")
	# List of Utils
	LOU="ip brctl tunctl netstat"

	# set $util to path of util for all in $LOU
	for U in $LOU
	do
		eval ${U}="`whereis -b $U |
			awk '{ if($2 != "")
					print $2;
				else
					print "void";
			}'`"
	done

	ERR=0
	# check brctl to exist
	if test $brctl = "void"
	then
		echo 'No brctl program -- please install package bridge-utils'
		ERR=1
	fi

	# check tunctl to exist
	if test $tunctl = "void"
	then
		echo 'No tunctl program -- please install package uml-utilities'
		ERR=1
	fi

	# quit when either not installed
	if test $ERR -eq 1
	then
		exit 1
	fi

	# make list of all interfaces ignoring lo
	AVL_IF=`$ip link show |
		grep '^[0-9]' |
		awk -F: '{ print $2 }' |
		grep -v 'lo' |
		sed '1,$s/^ //'`

	# found br0 in active interfaces?
	L=`echo $AVL_IF | tr ' ' '\012' | grep '^br0$' | wc -l`
	if test $L -ne 0
	then
		echo "$0: br0 already configured."
		echo "-- if you configured br0 statically don't use this script"
		echo "-- otherwise if you do not want permanent settings"
		echo "-- and want br0 configured differently reboot first"
		exit 1
	fi

	;;
esac

# let user chose the interface he/she wants to use
echo "  Available networkinterfaces"
N=0
for I in $AVL_IF
do
	N=`expr $N + 1`
	case $OS in
	 "FreeBSD" | "OpenBSD" | "NetBSD")
		IPCMD="$ifconfig $I "
		;;
	 "Linux")
		IPCMD="$ip addr show $I "
		;;
	esac

	L=`$IPCMD |
		grep 'inet' |
		grep -v 'inet6' |
		wc -l`
	if test $L -eq 0
	then
		M="not configured"
	else
		M=`$IPCMD |
			grep 'inet' |
			grep -v 'inet6' |
			awk '{ print $2 }' `
	fi

	# did we see wlan? alas...
	L=`echo $I | grep wlan | wc -l`
	if test $L -gt 0
	then
		M="$M (wlan not supported)"
		echo "-: $I $M"
		N=`expr $N - 1`
	else
		if test -r SnetSaved.$I
		then
			echo "$N: $I $M (saved params available)"
		else
			echo "$N: $I $M"
		fi
	fi
done
# take wlan out
AVL_IF=`echo $AVL_IF | sed 's/wlan.//'`

if test $N -gt 1
then
	ANSWER=0
	while test $ANSWER -lt 1 -o $ANSWER -gt $N
	do
		echo -n "Which interface do you want to use? "
		read ANSWER
	done
else
	ANSWER=1
fi

N=0
for I in $AVL_IF
do
	N=`expr $N + 1`
	if test $N -eq $ANSWER
	then
		ACT_IF=$I
	fi
done

# see if there are saved params for this interface
if test -r SnetSaved.$ACT_IF
then
	. ./SnetSaved.$ACT_IF
	echo "Saved params loaded from SnetSaved.$ACT_IF" 
fi

echo ""
echo "Interface to use for SIMH......... " $ACT_IF

if test "x$IPNR" = "x"
then
	case $OS in
	 "FreeBSD" | "OpenBSD" | "NetBSD")
		IPCMD="$ifconfig $ACT_IF "
		;;
	 "Linux")
		IPCMD="$ip addr show dev $ACT_IF "
		;;
	esac

	L=`$IPCMD |
		grep inet |
		grep -v inet6 |
		wc -l`
	if test $L -eq 0
	then
		IPNR="not configured"
	else
		IPNR=`$IPCMD |
			grep inet |
			grep -v inet6 |
			awk '{ print $2 }' `
	fi
fi
echo "IPnumber on this interface........ " $IPNR

if test "x$IPBRO" = "x"
then
	case $OS in
	 "FreeBSD" | "OpenBSD" | "NetBSD")
		IPCMD="$ifconfig $ACT_IF "
		SEDBRO='1s/^.*broadcast //'
		;;
	 "Linux")
		IPCMD="$ip addr show dev $ACT_IF "
		SEDBRO='1s/^.*brd //'
		;;
	esac

	IPBRO=`$IPCMD |
		grep inet |
		grep -v inet6 |
		sed "$SEDBRO" |
		sed '1s/[ 	].*$//'`
fi
echo "IP Broadcast on this interface.... " $IPBRO

if test "x$DEFRT" = "x"
then
	case $OS in
	 "FreeBSD" | "OpenBSD" | "NetBSD")
		DEFRT=`$netstat -rn |
			grep $ACT_IF |
			grep 'default' |
			awk '{ print $2 }'` 
		;;
	 "Linux")
		DEFRT=`$netstat -rn |
			grep $ACT_IF |
			grep '^0\.' |
			uniq |
			awk '{ print $2 }'` 
		;;
	esac
fi
if test "x$DEFRT" = "x"
then
	echo "Default Route set to Gateway...... " none
else
	echo "Default Route set to Gateway...... " $DEFRT
fi

if test "x$OS" = "xLinux"
then
	if test "x$IPFWD" = "x"
	then
		IPFWD=`cat /proc/sys/net/ipv4/ip_forward`
	fi
	if test $IPFWD -eq 1
	then
		echo "IP forwarding is active........... " YES
	else
		echo "IP forwarding is active........... " NO
	fi
fi

# nr of taps the user wants or 1 for default
if test "x${NrTaps}" = "x"
then
	NrTaps=1
fi
echo "Number of taps to create.......... " $NrTaps


# the user who needs access to the tap
if test "x$SimhUser" = "x"
then
	case $OS in
	 "FreeBSD" | "OpenBSD" | "NetBSD")
		SimhUser="root"
		;;
	 "Linux")
		if test "x${SUDO_USER}" != "x"
		then
			SimhUser=${SUDO_USER}
		else
			SimhUser=${USER}
		fi
		;;
	esac
fi
echo "User who runs SIMH on the taps.... " $SimhUser

# only save params when in expert OPSMODE
if test "X$OPSMODE" = "Xexpert"
then
	if test ! -r SnetSaved.$ACT_IF
	then
		cat - > SnetSaved.$ACT_IF <<EOF
#
# expert users: edit your params and rerun the SetupNet script
#

# ipnr including mask
IPNR=$IPNR
# do we forward between interfaces 0=no 1=yes
IPFWD=$IPFWD
# default gateway
DEFRT=$DEFRT
# nr of SIMH emulators you want in parallel that use network
NrTaps=$NrTaps
# username of the user running the SIMH emulators
SimhUser=$SimhUser
EOF

		L=`ls -l SnetSaved.$ACT_IF | grep root | wc -l`
		if test $L -eq 1
		then
			chown $SimhUser SnetSaved.$ACT_IF
		fi
	fi
fi

JOBFILE="/tmp/SNjob.$$"
TMPFILE="/tmp/SNtmp.$$"

cat - > $JOBFILE <<\EOF
#!/bin/sh

# This script should be run under root permission

EOF

cat - > $TMPFILE <<\EOF
echo ${CMD}
${CMD}
if test $? -ne 0
then
	echo '*** FAIL:' ${CMD}
	exit 1
fi

EOF

case $OS in
 "Linux")
	echo "CMD=\"$brctl addbr br0\"" >> $JOBFILE
	cat $TMPFILE >> $JOBFILE

	N=0
	while test $N -lt $NrTaps
	do
		echo "CMD=\"$tunctl -t tap${N} -u ${SimhUser}\"" >> $JOBFILE
		cat $TMPFILE >> $JOBFILE

		N=`expr $N + 1`
	done

	echo "CMD=\"$brctl addif br0 ${ACT_IF}\"" >> $JOBFILE
	cat $TMPFILE >> $JOBFILE

	echo "CMD=\"$brctl setfd br0 0\"" >> $JOBFILE
	cat $TMPFILE >> $JOBFILE

	echo "CMD=\"$ip link set ${ACT_IF} down\"" >> $JOBFILE
	cat $TMPFILE >> $JOBFILE

	if ! test "$IPNR" = "not configured"
	then
		echo "CMD=\"$ip addr add ${IPNR} dev br0\"" >> $JOBFILE
		cat $TMPFILE >> $JOBFILE
	fi

	if ! test "$IPNR" = "not configured"
	then
		## if test ! "x$DEFRT" = "x"
		## then
			## echo "CMD=\"$ip route del default via ${DEFRT} dev ${ACT_IF}\"" >> $JOBFILE
			## cat $TMPFILE >> $JOBFILE
		## fi
		echo "CMD=\"$ip addr del ${IPNR} dev ${ACT_IF}\"" >> $JOBFILE
		cat $TMPFILE >> $JOBFILE
	fi

	echo "CMD=\"$ip link set ${ACT_IF} up\"" >> $JOBFILE
	cat $TMPFILE >> $JOBFILE

	echo "CMD=\"$ip link set br0 up\"" >> $JOBFILE
	cat $TMPFILE >> $JOBFILE


	if test ! "x$DEFRT" = "x"
	then
		echo "CMD=\"$ip route add default via ${DEFRT} dev br0\"" >> $JOBFILE
		cat $TMPFILE >> $JOBFILE
	fi

	ipfwd=`cat /proc/sys/net/ipv4/ip_forward`
	if test $IPFWD -ne $ipfwd
	then
		echo "CMD=\"echo ${IPFWD} > /proc/sys/net/ipv4/ip_forward\"" >> $JOBFILE
		cat $TMPFILE >> $JOBFILE
	fi

	N=0
	while test $N -lt $NrTaps
	do
		echo "CMD=\"$brctl addif br0 tap${N}\"" >> $JOBFILE
		cat $TMPFILE >> $JOBFILE

		echo "CMD=\"$ip link set tap${N} up\"" >> $JOBFILE
		cat $TMPFILE >> $JOBFILE

		N=`expr $N + 1`
	done
	BRIDGE="br0"
	EXAMPLE="tap:tap0"

	;;
  "FreeBSD")
	N=0
	while test $N -lt $NrTaps
	do
		echo "CMD=\"$ifconfig tap${N} create\"" >> $JOBFILE
		cat $TMPFILE >> $JOBFILE

		N=`expr $N + 1`
	done

	echo "CMD=\"$sysctl net.link.tap.up_on_open=1\"" >> $JOBFILE
	cat $TMPFILE >> $JOBFILE

	echo "CMD=\"$ifconfig bridge0 create\"" >> $JOBFILE
	cat $TMPFILE >> $JOBFILE

	case $NrTaps in
	  1 )
		echo "CMD=\"$ifconfig bridge0 addm ${ACT_IF} addm tap0\"" >> $JOBFILE
		;;
	  2 )
		echo "CMD=\"$ifconfig bridge0 addm ${ACT_IF} addm tap0 addm tap1\"" >> $JOBFILE
		;;
	  3 )
		echo "CMD=\"$ifconfig bridge0 addm ${ACT_IF} addm tap0 addm tap1 addm tap2\"" >> $JOBFILE
		;;
	  4 )
		echo "CMD=\"$ifconfig bridge0 addm ${ACT_IF} addm tap0 addm tap1 addm tap2 addm tap3\"" >> $JOBFILE
		;;
	  * )
		echo "Sorry too many taps..."
		exit
	esac
	cat $TMPFILE >> $JOBFILE

	echo "CMD=\"$ifconfig bridge0 up\"" >> $JOBFILE
	cat $TMPFILE >> $JOBFILE
	BRIDGE="bridge0"
	EXAMPLE="tap:tap0"
	;;
  "OpenBSD")
	N=0
	while test $N -lt $NrTaps
	do
		echo "CMD=\"$ifconfig tap${N} create\"" >> $JOBFILE
		cat $TMPFILE >> $JOBFILE

		echo "CMD=\"$ifconfig tap${N} up\"" >> $JOBFILE
		cat $TMPFILE >> $JOBFILE

		N=`expr $N + 1`
	done

	echo "CMD=\"$ifconfig bridge0 create\"" >> $JOBFILE
	cat $TMPFILE >> $JOBFILE

	echo "CMD=\"$ifconfig bridge0 fwddelay 4\"" >> $JOBFILE
	cat $TMPFILE >> $JOBFILE

	case $NrTaps in
	  1 )
		echo "CMD=\"$ifconfig bridge0 add ${ACT_IF} add tap0\"" >> $JOBFILE
		;;
	  2 )
		echo "CMD=\"$ifconfig bridge0 add ${ACT_IF} add tap0 add tap1\"" >> $JOBFILE
		;;
	  3 )
		echo "CMD=\"$ifconfig bridge0 add ${ACT_IF} add tap0 add tap1 add tap2\"" >> $JOBFILE
		;;
	  4 )
		echo "CMD=\"$ifconfig bridge0 add ${ACT_IF} add tap0 add tap1 add tap2 add tap3\"" >> $JOBFILE
		;;
	  * )
		echo "Sorry too many taps..."
		exit
	esac
	cat $TMPFILE >> $JOBFILE

	echo "CMD=\"$ifconfig bridge0 up\"" >> $JOBFILE
	cat $TMPFILE >> $JOBFILE
	BRIDGE="bridge0"
	EXAMPLE="tap:tap0"
	;;
  "NetBSD")
	N=0
	while test $N -lt $NrTaps
	do
		echo "CMD=\"$ifconfig tap${N} create\"" >> $JOBFILE
		cat $TMPFILE >> $JOBFILE

		echo "CMD=\"$ifconfig tap${N} up\"" >> $JOBFILE
		cat $TMPFILE >> $JOBFILE

		N=`expr $N + 1`
	done

	echo "CMD=\"$ifconfig bridge0 create\"" >> $JOBFILE
	cat $TMPFILE >> $JOBFILE

	echo "CMD=\"$brconfig bridge0 fwddelay 1\"" >> $JOBFILE
	cat $TMPFILE >> $JOBFILE

	case $NrTaps in
	  1 )
		echo "CMD=\"$brconfig bridge0 add ${ACT_IF} add tap0\"" >> $JOBFILE
		;;
	  2 )
		echo "CMD=\"$brconfig bridge0 add ${ACT_IF} add tap0 add tap1\"" >> $JOBFILE
		;;
	  3 )
		echo "CMD=\"$brconfig bridge0 add ${ACT_IF} add tap0 add tap1 add tap2\"" >> $JOBFILE
		;;
	  4 )
		echo "CMD=\"$brconfig bridge0 add ${ACT_IF} add tap0 add tap1 add tap2 add tap3\"" >> $JOBFILE
		;;
	  * )
		echo "Sorry too many taps..."
		exit
	esac
	cat $TMPFILE >> $JOBFILE

	echo "CMD=\"$brconfig bridge0 up\"" >> $JOBFILE
	cat $TMPFILE >> $JOBFILE

	BRIDGE="bridge0"
	EXAMPLE="tap:tap0"
	;;
esac

	cat - >> $JOBFILE <<EOF
echo ""
echo 'Network reconfigured for use by SIMH simulators'
echo "Bridge ${BRIDGE} with accesspoint wired into interface ${ACT_IF}"
echo "Attach ethernet interface to ${EXAMPLE} in SIMH ini file."
echo ""
echo 'Use unique IPnrs on your SIMH hosts within the'
echo 'same network and set a default route if needed'

rm -f $JOBFILE
EOF

if test "X$OPSMODE" = "Xexpert"
then
	echo ""
	echo "-- To change the params above edit SnetSaved.$ACT_IF"
	echo "-- and rerun this script before executing the job"
fi

L=`ls -l $JOBFILE | grep root | wc -l`
if test $L -gt 0
then
	echo "Executing $JOBFILE ..."
	echo -n "Proceed...?  (y)/n "
	read ANSWER
	if test "x$ANSWER" = "xn"
	then
		echo "-- To execute: sh $JOBFILE"
		exit 0
	fi
	sh ${JOBFILE}
else
	echo ""
	echo "-- Executing $JOBFILE requires root permission"
	echo "-- Either use sudo or su to execute: sh $JOBFILE"
fi

rm -f $TMPFILE