#!/bin/sh
#
# Marta Carbone, Luigi Rizzo
# Copyright (C) 2009 Universita` di Pisa
# $Id$
#
# This script the vsys backend used to configure emulation.
# In detail it:
# - reads the user's input from the vsys input pipe
# - validates the input
# - configures the firewall
# - writes results on the output vsys pipe
#
# Configurable variables are at the beginning

# If HOOK is set the program is called before configuring a rule.
# A sample hook can be found in the ipfw.rpm package
# HOOK=/tmp/sample_hook
# XXX HOOK=""

# You should not touch anything below.

# We assume three type of connections
#  SERVER we know the local port P, and do the
#	bind/listen/accept on the local socket.
#		pipe_in in dst-port P
#		pipe_out out src-port P
#
#  CLIENT we know the remote port P, and do a connect to it
#	(src and dst are swapped wrt the previous case)
#		pipe_in in src-port P
#		pipe_out out dst-port P
#
#  SERVICE we run a server on local port P, and also connect
#	from local clients to remote servers on port P.
#		pipe_in in { dst-port P or src-port P }
#		pipe_out out { src-port P or dst-port P }
# 
#  On a given port a user can have one CLIENT and/or one SERVER
#  configuration or one SERVICE configuration.
#  When a SERVICE configuration is installed any existing CLIENT
#  and SERVER configuration on the same port are removed.
#  When a CLIENT or SERVER configuration is installed any existing
#  SERVICE configuration on the same port is removed.
#
#  The following is a case that is implemented as SERVER
#  D	we run a server on local port P, and also connect
#	to remote servers but doing a bind(P) before connect().
#	In terms of rules, this is not distinguishable from
#	the SERVER case, however it would be different if we
#	had a way to tell SERVER from CLIENT sockets
#		pipe_in in dst-port P
#		pipe_out out src-port P
#
# The database of current ipfw and dummynet configuration is in a
# file which is regenerated on errors. The format is
#
#	slice_id type arg rule_base pipe_base timeout
#
# (lines starting with '#' are comments and are ignored)
# For each configuration we allocate one rule number in ipfw,
# and two sequential pipe numbers.

# globals, do not touch below
VERBOSE=0	# set to !0 to enable debug messages
TEST=0		# set to 1 for test mode

DBFILE=/tmp/ff
lockfile=/var/lock/ipfw.lock

# There values are the keys used in the database for rules and pipes
# rule_nr 1..10000 are mapped to rules 10000..49999 (n*4+9996)
# rule_nr 10001..20000 are mapped to rules 50000..59999 (n+39999)
# pipe_nr 1..25000 are mapped to pipes 10000-59999 (n*2+9998)
RULE_BL_MIN=1
RULE_BL_MAX=10000
RULE_IN_MIN=10001
RULE_IN_MAX=20000
PIPE_MIN=1
PIPE_MAX=25000
# These are the rule numbers used in ipfw
IPFW_RULE_MIN=10000
IPFW_RULE_MAX=59999
IPFW_PIPE_MIN=10000
IPFW_PIPE_MAX=59999

# set slicename and slice_id
# there represents the credential of the user
SLICENAME=$1
SLICE_ID=`id -u $SLICENAME`
[ $? != 0 ] && abort "Invalid slicename $SLICENAME"

# programs
# XXX check consistency for variables {}
SED=/bin/sed
SEDOPT=-r
[ -x ${SED} ] || { SED=`which sed` ; SEDOPT=-E ; }
IPFW=/sbin/ipfw
IPFW_CHECK="/sbin/ipfw -n"

debug() { # $1 message to be displayed
	[ x"${VERBOSE}" != x"0" ] && echo "ipfw-be: $1"
}
# if the first argument is -v, enable verbose mode
set_verbose() {
    [ x"$1" = x"-v" -o x"$2" = x"-v" ] && VERBOSE=1
}
set_test() {
    [ x"$1" = x"-q" -o x"$2" = x"-q" ] || return
    TEST=1
    IPFW="/bin/echo ipfw:"
    IPFW_CHECK="/bin/echo ipfw -n:"
}


abort() { # $1 message to be displayed
	release_lock
	echo "ipfw-be aborting: $1"
	exit 1
}

# remove dangerous characters from user input
# if present, the leading '-v/-t' will be removed
filter() { # $* variables to be filtered
	[ x${1} = x"-v" -o x${1} = x"-q" ] && shift
	[ x${1} = x"-v" -o x${1} = x"-q" ] && shift
	# allowed chars are: numbers, uppercase and lowercase letters,
	# spaces, and the following symbols: .,_-/
	echo "$*" | ${SED} ${SEDOPT} 's/[^\t0-9a-zA-Z., _\/\{}-]*//g'
}

# remove all entries from the ipfw config, and create an empty db
clean_db() {
	rm -f ${DBFILE}
	touch ${DBFILE}
	# we would like to delete ranges of rules and pipes but this
	# is not supported so for the time being we kill them all
	${IPFW} -q flush
	${IPFW} -q pipe flush
	# ${IPFW} delete ${IPFW_RULE_MIN}-${IPFW_RULE_MAX}
	# ${IPFW} pipe delete ${IPFW_PIPE_MIN}-${IPFW_PIPE_MAX}
}

# Add the ipfw rule/pipe and update the database.
# The pipe-in and pipe_out config are through global variables
# CONFIG_IN CONFIG_OUT because they may be long.
# Other arguments are on the command line
add_rule() { # new_rule slice_id type arg rule pipe_base timeout
    local new_rule=$1 slice_id=$2 type=$3 arg=$4
    local rule_base=$5 pipe_base=$6 timeout=$7
    local pipe_in pipe_out rule_in rule_out check_timeout

    # If we use a profile file, locate the user directory
    # move in the slice root dir XXX todo
    [ "$TEST" != "1" ] && cd /vservers/${SLICENAME}/root
    #echo ${CONFIG_STRING} | ${SED} -e "s/ profile \(.[^ ]\)/ profile \/vservers\/${SLICENAME}\/\1/g"

    # first, call ipfw -n to check syntax, if ok move on and do the action
    pipe_in=$(($pipe_base + $pipe_base + 9998))
    pipe_out=$(($pipe_in + 1))
    local del	# anything to delete ?
    local rule_nr=$(($rule_base + 39999))  # XXX formula for individual rules
    if [ x"$new_rule" != x"0" ] ; then
	case $type in
	server)
	    rule_in="dst-port $arg"
	    rule_out="src-port $arg"
	    del=service
	    ;;
	client)
	    rule_in="src-port $arg"
	    rule_out="dst-port $arg"
	    del=service
	    ;;
	service)
	    rule_in="{ src-port $arg or dst-port $arg }"
	    rule_out="{ src-port $arg or dst-port $arg }"
	    del="cli_ser"
	    ;;
	*)
	    abort "invalid service type $type"
	    ;;
	esac

	rule_in="pipe ${pipe_in} in uid $slice_id ${rule_in}"
	rule_out="pipe ${pipe_out} out uid $slice_id ${rule_out}"
	${IPFW_CHECK} add ${rule_nr} $rule_in > /dev/null || \
		abort "ipfw syntax error $rule_in"
	${IPFW_CHECK} add ${rule_nr} $rule_out > /dev/null || \
		abort "ipfw syntax error $rule_out"
    fi

    # check error reporting
    ${IPFW_CHECK} pipe ${pipe_in} config ${CONFIG_PIPE_IN} > /dev/null || \
		abort "ipfw syntax error pipe_in"
    ${IPFW_CHECK} pipe ${pipe_out} config ${CONFIG_PIPE_OUT} > /dev/null || \
		abort "ipfw syntax error pipe_out"

    # all good, delete and add rules if necessary
    [ "$del" = "service" ] && do_delete $slice_id service $arg
    [ "$del" = "cli_ser" ] && do_delete $slice_id client $arg
    [ "$del" = "cli_ser" ] && do_delete $slice_id server $arg
    [ "$new_rule" != "0" ] && ${IPFW} add ${rule_nr} $rule_in > /dev/null
    [ "$new_rule" != "0" ] && ${IPFW} add ${rule_nr} $rule_out > /dev/null
    # config pipes
    ${IPFW} pipe ${pipe_in} config ${CONFIG_PIPE_IN}
    ${IPFW} pipe ${pipe_out} config ${CONFIG_PIPE_OUT}

    # send output to the user
    ${IPFW} show ${rule_nr}
    ${IPFW} pipe ${pipe_in} show
    ${IPFW} pipe ${pipe_out} show

    [ "$TEST" = "1" ] && return
    # add to the database, at least to adjust the timeout
    ( grep -v -- "^${slice_id} ${type} ${arg} " $DBFILE;  \
	echo "${slice_id} ${type} ${arg} ${rule_base} ${pipe_base} ${timeout}" ) > ${DBFILE}.tmp
    mv ${DBFILE}.tmp ${DBFILE}
}

# Delete a given configuration
do_delete() { # slice_id type arg
    local pipe_in pipe_out pipe_base rule_base rule_nr
    local slice_id=$1 type=$2 arg=$3

    [ "${arg}" = "" ] && abort "Missing arg on 'delete'"
    set `find_rule $slice_id $type $arg`
    rule_base=$1; pipe_base=$2
    [ "$rule_base" = "0" ] && return		# no rules found

    rule_nr=$(($rule_base + 39999))		# XXX only individual rules
    pipe_in=$(($pipe_base + $pipe_base + 9998))
    pipe_out=$(($pipe_in + 1))

    $IPFW delete ${rule_nr}
    $IPFW pipe delete ${pipe_in}
    $IPFW pipe delete ${pipe_out}
    echo "removed configuration $slice_id} ${type} ${arg}"
    [ "$TEST" = "1" ] && return
    # remove from the database
    grep -v -- "^${slice_id} ${type} ${arg} " $DBFILE > ${DBFILE}.tmp
    mv ${DBFILE}.tmp ${DBFILE}
}

# called with the database file as input
# compare the tuple <slice_id type arg> with
# the current firewall configuration. The database contains
# 	slice_id type arg rule_base pipe_base timeout
# On match returns <rule_base pipe_base timeout>
# On non match returns 0 0 0
find_rule() { # $1 slice_id $2 type $3 arg
    local ret
    ret=`grep -- "^$1 $2 $3 " $DBFILE`

    [ x"$ret" = x ] && echo "0 0 0 " && return	# nothing found
    # ignore multiple matches. If the db is corrupt we are
    # screwed anyways
    set $ret
    echo "$4 $5 $6"
}


# Find a hole in a list of numbers within a range (boundaries included)
# The input is passed as a sorted list of numbers on stdin.
# Return a "0" rule if there is no rule free
find_hole() {  # min max
    local min=$1 cand=$1 max=$2 line
    while read line ; do
	[ $line -lt $min ] && continue
        [ $line -ne $cand ] && break		# found
	[ $cand -ge $max ] && cand=0 && break	# no space
        cand=$(($cand + 1))
    done
    echo $cand
}

# returns a free rule and pipe base for client|server|service
# Returns r=0 if there are no resources available
allocate_resources() {
    local p r
    # remove comments, extract field, sort
    p=`grep -v '^#' $DBFILE | awk '{print $5}' | sort -n | \
	find_hole $PIPE_MIN $PIPE_MAX`
    r=`grep -v '^#' $DBFILE | awk '{print $4}' | sort -n | find_hole $1 $2`
    [ $r = 0 -o $p = 0 ] && r=0 		# no resources available
    echo $r $p
}

# process a request.
# A request is made by a set of arguments formatted as follow:
#
# config {server|client|service} arg [-t timeout] PIPE_IN <pipe_conf> PIPE_OUT <pipe_conf>
# show {rules|pipes} [args]
# delete type arg
#
# XXX not implemented yet
# config {rule|pipe} num <parameters>
# alloc rules|pipes [-t timeout] # returns a block of NUM_RULES or NUM_PIPES
# release rules|pipes args	# release the entire block
# refresh rules|pipes args [-t timeout]
#
# where uppercase values are keywords.
# The timeout value is expressed as:
# week, day, month or anything else accepted by the date command.
# The id of the slice issuing the request is in the $SLICE_ID variable,
# set at the beginning of this script.
process() {
    local new_pipe=0
    local timeout TMP i rule_base pipe_base
    local slicename=${SLICENAME}
    local cmd=$1 ; shift
    local debug_args="$*";
    local type=$1 ; shift
    local args="$*"
    debug "Received command: <$cmd> arguments: <$debug_args>"

    # set the timeout value
    # clean args from the timeout keyword
    timeout=`echo ${args} | ${SED} ${SEDOPT} 's/(.+)( -t [a-zA-Z0-9]+ )(.*)/\2/'`
    if [ "${timeout}" != "${args}" ] ; then 	# match
	timeout=`echo ${timeout} | ${SED} ${SEDOPT} 's/-t //'`
	check_timeout ${timeout}	# abort on error
	args=`echo ${args} | ${SED} ${SEDOPT} 's/(.+)( -t [a-zA-Z0-9]+ )(.*)/\1 \3/'`
    else
	timeout=1day		# default to 1 day
    fi

    debug "Timeout $timeout"
    # Handle special requests: show and delete
    case x"$cmd" in 
    x"alloc") 
	abort "XXX unimplemented " && return 0
	;;
    x"config") 
	[ "$type" = "server" ] && do_config $SLICE_ID $timeout $type $args && return 0
	[ "$type" = "client" ] && do_config $SLICE_ID $timeout $type $args && return 0
	[ "$type" = "service" ] && do_config $SLICE_ID $timeout $type $args && return 0
	[ "$type" = "rule" ] && abort "XXX unimplemented " && return 0
	[ "$type" = "pipe" ] && abort "XXX unimplemented " && return 0
	abort "'config' should be followed by {server|client|service|rule|pipe}"
	;;
    x"delete") 
	do_delete ${SLICE_ID} $type $args
	;;
    x"refresh") 
	abort "XXX unimplemented " && return 0
	do_refresh ${SLICE_ID} $type $args $timeout
	;;
    x"release") 
	abort "XXX unimplemented " && return 0
	do_release ${SLICE_ID} $type $args
	;;
    x"show")
	# XXX should filter on uid
	[ "$type" = "rules" ] && ${IPFW} show && return 0
	[ "$type" = "pipes" ] && ${IPFW} pipe show && return 0
	abort "'show' should be followed by {rules|pipes}"
	;;
    *)
	# help XXX to be done
	abort "'command' should be one of {show|config|delete|refresh|release}"
	;;
    esac
}

# validate the timeout
check_timeout() { # timeout
    local tt=`date --date="${1}" +%s`
    [ "$?" != "0" ] && abort "Date format $1 not valid"
}

do_release() { # slice_id type args timeout
    return
}

do_refresh() { # slice_id ttype args
    return
}

do_config() { # slice_id timeout type arg PIPE_IN pipe_conf PIPE_OUT pipe_conf
    local slice_id=$1; shift
    local timeout=$1; shift
    local type=$1; shift
    local arg=$1; shift	# XXX addr not yet implemented

    [ "$1" != "PIPE_IN" ] && abort "Missing addr:port, or PIPE_IN requested"
    shift

    # read pipe in configuration
    i=""
    while [ "$1" != "" -a "$1" != "PIPE_OUT" ] ; do
	i="$i $1"
	shift
    done
    CONFIG_PIPE_IN="$i"		# XXX local ?
    [ "$CONFIG_PIPE_IN" = "" ] && abort "Missing pipe in configuration"

    [ "$1" != "PIPE_OUT" ] && abort "Missing pipe in configuration, or missing PIPE_OUT"
    shift

    # read pipe out configuration
    i=""
    while [ "$1" != "" ] ; do
	i="$i $1"
	shift
    done
    CONFIG_PIPE_OUT="$i"	# XXX local ?
    [ "$CONFIG_PIPE_OUT" = "" ] && abort "Missing pipe out configuration"

    debug "Configuration Required:"
    debug "slice_id: $slice_id"
    debug "type: $type"
    debug "arg: $arg"
    debug "timeout: $timeout"
    debug "PIPE_IN: $CONFIG_PIPE_IN"
    debug "PIPE_OUT: $CONFIG_PIPE_OUT"
    debug "-----------------------"

    # check if the link is already configured
    debug "Search for ${slice_id} ${type} ${arg}"

    set `find_rule ${slice_id} ${type} ${arg}`
    local rule_base=$1
    local pipe_base=$2
    local new_pipe=0

    if [ ${rule_base} = "0" ] ; then
	debug "Rule not found, new installation"
	new_pipe=1
	set `allocate_resources $RULE_IN_MIN $RULE_IN_MAX`
	rule_base=$1; pipe_base=$2
        [ $rule_base = 0 ] && abort "no resources available"
	debug "found free resources rule: $rule_base pipe: $pipe_base"
    else
	debug "Rule found, just changing the pipe configuration"
    fi

    add_rule $new_pipe $slice_id $type $arg $rule_base $pipe_base $timeout

    # if present, call a hook in order to collect statistical
    # information on dummynet usage
    if [ -n "${HOOK}" -a -x "${HOOK}" ]; then
	# XXX
	${HOOK} $slice_id $type $port $rule_base $pipe_base $timeout &
    fi
}

#
# acquire the lock XXX check lockfile
acquire_lock() {
    [ "$TEST" = 1 ] && return
    lockfile -s 0 -r 0 $lockfile 2> /dev/null
    if [ $? -ne 0 ] ; then
	echo "lock acquisition failed"
	exit -1
    fi
}

#
# release the lock
release_lock() {
    rm -f $lockfile
}

# ALLOCATION OF PIPES AND RULES
# pipes are always allocated in pairs
# rules are either individual or in groups of size NUM_RULES (e.g. 4)
# and are allocated in two different parts of the rule namespace
# (e.g. blocks from 10000 to 49999 and individuals from 50000 to 59999)
# Internally allocator uses the base number for each item, e.g.
# rule 10000..49999 -> rule_base=1..10000
# rule 50000..59999 -> rule_base=10001..20000
# pipe 10000..59999 -> pipe_base=1..25000
# a bit of math lets us compute the correct numbers.
# For CLIENT, SERVER, SERVICE the database contains entries as
#	XID	TYPE	arg	rule_base	pipe_base
# For blocks the entries are
#	XID	RULE	-	rule_base	-
#	XID	PIPE	-	-		pipe_base
# When a rule or pipe is referenced we first check that the owner owns it.
# more details below.

#-- main starts here
debug "--- $0 START for $SLICENAME ---"

# If the db does not exist, create it and we clean rules and pipes
[ ! -e ${DBFILE} ] && clean_db

# A request to the vsys backend is composed by a single line of input
read REQ			# read one line, ignore the rest
set_verbose ${REQ}		# use inital -v if present
set_test ${REQ}		# use inital -t if present
REQ="`filter ${REQ}`"	# remove -v and -t and invalid chars
debug "--- processing <${REQ}>"
acquire_lock			# critical section
process ${REQ}
release_lock
debug "--- $0 END ---"
exit 0