#!/bin/sh
#-
# Copyright (c) 2016 Devin Teske
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
#
# $FreeBSD$
#
############################################################ IDENT(1)
#
# $Title: if_bridge(4) management script for vnet jails $
#
############################################################ INFORMATION
#
# Use this tool with jail.conf(5) (or rc.conf(5) ``legacy'' configuration) to
# manage `vnet' interfaces for jails. Designed to automate the creation of vnet
# interface(s) during jail `prestart' and destroy said interface(s) during jail
# `poststop'.
#
# In jail.conf(5) format:
#
# ### BEGIN EXCERPT ###
#
# xxx {
# 	host.hostname = "xxx.yyy";
# 	path = "/vm/xxx";
# 
# 	#
# 	# NB: Below 2-lines required
# 	# NB: The number of eNb_xxx interfaces should match the number of
# 	#     arguments given to `jib addm xxx' in exec.prestart value.
# 	#
# 	vnet;
# 	vnet.interface = "e0b_xxx e1b_xxx ...";
# 
# 	exec.clean;
# 	exec.system_user = "root";
# 	exec.jail_user = "root";
# 
# 	#
# 	# NB: Below 2-lines required
# 	# NB: The number of arguments after `jib addm xxx' should match
# 	#     the number of eNb_xxx arguments in vnet.interface value.
# 	#
# 	exec.prestart += "jib addm xxx em0 em1 ...";
# 	exec.poststop += "jib destroy xxx";
# 
# 	# Standard recipe
# 	exec.start += "/bin/sh /etc/rc";
# 	exec.stop = "/bin/sh /etc/rc.shutdown";
# 	exec.consolelog = "/var/log/jail_xxx_console.log";
# 	mount.devfs;
#
# 	# Optional (default off)
# 	#allow.mount;
# 	#allow.set_hostname = 1;
# 	#allow.sysvipc = 1;
# 	#devfs_ruleset = "11"; # rule to unhide bpf for DHCP
# }
#
# ### END EXCERPT ###
#
# In rc.conf(5) ``legacy'' format (used when /etc/jail.conf does not exist):
#
# ### BEGIN EXCERPT ###
#
# jail_enable="YES"
# jail_list="xxx"
#
# #
# # Global presets for all jails
# #
# jail_devfs_enable="YES"	# mount devfs
#
# #
# # Global options (default off)
# #
# #jail_mount_enable="YES"		# mount /etc/fstab.{name}
# #jail_set_hostname_allow="YES"	# Allow hostname to change
# #jail_sysvipc_allow="YES"		# Allow SysV Interprocess Comm.
# 
# # xxx
# jail_xxx_hostname="xxx.shxd.cx"		# hostname
# jail_xxx_rootdir="/vm/xxx"			# root directory
# jail_xxx_vnet_interfaces="e0b_xxx e1bxxx ..."	# vnet interface(s)
# jail_xxx_exec_prestart0="jib addm xxx em0 em1 ..."	# bridge interface(s)
# jail_xxx_exec_poststop0="jib destroy xxx"	# destroy interface(s)
# #jail_xxx_mount_enable="YES"			# mount /etc/fstab.xxx
# #jail_xxx_devfs_ruleset="11"			# rule to unhide bpf for DHCP
#
# ### END EXCERPT ###
#
# Note that the legacy rc.conf(5) format is converted to
# /var/run/jail.{name}.conf by /etc/rc.d/jail if jail.conf(5) is missing.
#
# ASIDE: dhclient(8) inside a vnet jail...
#
# To allow dhclient(8) to work inside a vnet jail, make sure the following
# appears in /etc/devfs.rules (which should be created if it doesn't exist):
#
# 	[devfsrules_jail=11]
# 	add include $devfsrules_hide_all
# 	add include $devfsrules_unhide_basic
# 	add include $devfsrules_unhide_login
# 	add path 'bpf*' unhide
#
# And set ether devfs.ruleset="11" (jail.conf(5)) or
# jail_{name}_devfs_ruleset="11" (rc.conf(5)).
#
# NB: While this tool can't create every type of desirable topology, it should
# handle most setups, minus some which considered exotic or purpose-built.
#
############################################################ GLOBALS

pgm="${0##*/}" # Program basename

#
# Global exit status
#
SUCCESS=0
FAILURE=1

############################################################ FUNCTIONS

usage()
{
	local action usage descr
	exec >&2
	echo "Usage: $pgm action [arguments]"
	echo "Actions:"
	for action in \
		addm		\
		show		\
		show1		\
		destroy		\
	; do
		eval usage=\"\$jib_${action}_usage\"
		[ "$usage" ] || continue
		eval descr=\"\$jib_${action}_descr\"
		printf "\t%s\n\t\t%s\n" "$usage" "$descr"
	done
	exit $FAILURE
}

action_usage()
{
	local usage action="$1"
	eval usage=\"\$jib_${action}_usage\"
	echo "Usage: $pgm $usage" >&2
	exit $FAILURE
}

derive_mac()
{
	local OPTIND=1 OPTARG __flag
	local __mac_num= __make_pair=
	while getopts 2n: __flag; do
		case "$__flag" in
		2) __make_pair=1 ;;
		n) __mac_num=${OPTARG%%[^0-9]*} ;;
		esac
	done
	shift $(( $OPTIND - 1 ))

	if [ ! "$__mac_num" ]; then
		eval __mac_num=\${_${iface}_num:--1}
		__mac_num=$(( $__mac_num + 1 ))
		eval _${iface}_num=\$__mac_num
	fi

	local __iface="$1" __name="$2" __var_to_set="$3" __var_to_set_b="$4"
	local __iface_devid __new_devid __num __new_devid_b
	#
	# Calculate MAC address derived from given iface.
	#
	# The formula I'm using is ``NP:SS:SS:II:II:II'' where:
	# + N denotes 4 bits used as a counter to support branching
	#   each parent interface up to 15 times under the same jail
	#   name (see S below).
	# + P denotes the special nibble whose value, if one of
	#   2, 6, A, or E (but usually 2) denotes a privately
	#   administered MAC address (while remaining routable).
	# + S denotes 16 bits, the sum(1) value of the jail name.
	# + I denotes bits that are inherited from parent interface.
	#
	# The S bits are a CRC-16 checksum of NAME, allowing the jail
	# to change link numbers in ng_bridge(4) without affecting the
	# MAC address. Meanwhile, if...
	#   + the jail NAME changes (e.g., it was duplicated and given
	#     a new name with no other changes)
	#   + the underlying network interface changes
	#   + the jail is moved to another host
	# the MAC address will be recalculated to a new, similarly
	# unique value preventing conflict.
	#
	__iface_devid=$( ifconfig $__iface ether | awk '/ether/,$0=$2' )
	# ??:??:??:II:II:II
	__new_devid=${__iface_devid#??:??:??} # => :II:II:II
	# => :SS:SS:II:II:II
	__num=$( set -- `echo -n "$__name" | sum` && echo $1 )
	__new_devid=$( printf :%02x:%02x \
		$(( $__num >> 8 & 255 )) $(( $__num & 255 )) )$__new_devid
	# => P:SS:SS:II:II:II
	case "$__iface_devid" in
	   ?2:*) __new_devid=a$__new_devid __new_devid_b=e$__new_devid ;;
	?[Ee]:*) __new_devid=2$__new_devid __new_devid_b=6$__new_devid ;;
	      *) __new_devid=2$__new_devid __new_devid_b=e$__new_devid
	esac
	# => NP:SS:SS:II:II:II
	__new_devid=$( printf %x $(( $__mac_num & 15 )) )$__new_devid
	__new_devid_b=$( printf %x $(( $__mac_num & 15 )) )$__new_devid_b

	#
	# Return derivative MAC address(es)
	#
	if [ "$__make_pair" ]; then
		if [ "$__var_to_set" -a "$__var_to_set_b" ]; then
			eval $__var_to_set=\$__new_devid
			eval $__var_to_set_b=\$__new_devid_b
		else
			echo $__new_devid $__new_devid_b
		fi
	else
		if [ "$__var_to_set" ]; then
			eval $__var_to_set=\$__new_devid
		else
			echo $__new_devid
		fi
	fi
}

mustberoot_to_continue()
{
	if [ "$( id -u )" -ne 0 ]; then
		echo "Must run as root!" >&2
		exit $FAILURE
	fi
}

jib_addm_usage="addm [-b BRIDGE_NAME] NAME [!]iface0 [[!]iface1 ...]"
jib_addm_descr="Creates e0b_NAME [e1b_NAME ...]"
jib_addm()
{
	local OPTIND=1 OPTARG flag bridge=bridge
	while getopts b: flag; do
		case "$flag" in
		b) bridge="${OPTARG:-bridge}" ;;
		*) action_usage addm # NOTREACHED
		esac
	done
	shift $(( $OPTIND - 1 ))

	local name="$1"
	[ "${name:-x}" = "${name#*[!0-9a-zA-Z_]}" -a $# -gt 1 ] ||
		action_usage addm # NOTREACHED
	shift 1 # name

	mustberoot_to_continue

	local iface eiface_devid_a eiface_devid_b
	local new no_derive num quad i=0
	for iface in $*; do

		no_derive=
		case "$iface" in
		!*) iface=${iface#!} no_derive=1 ;;
		esac

		# Make sure the interface doesn't exist already
		if ifconfig "e${i}a_$name" > /dev/null 2>&1; then
			i=$(( $i + 1 ))
			continue
		fi

		# Bring the interface up
		ifconfig $iface up || return

		# Make sure the interface has been bridged
		if ! ifconfig "$iface$bridge" > /dev/null 2>&1; then
			new=$( ifconfig bridge create ) || return
			ifconfig $new addm $iface || return
			ifconfig $new name "$iface$bridge" || return
			ifconfig "$iface$bridge" up || return
		fi

		# Create a new interface to the bridge
		new=$( ifconfig epair create ) || return
		ifconfig "$iface$bridge" addm $new || return

		# Rename the new interface
		ifconfig $new name "e${i}a_$name" || return
		ifconfig ${new%a}b name "e${i}b_$name" || return
		ifconfig "e${i}a_$name" up || return
		ifconfig "e${i}b_$name" up || return

		#
		# Set the MAC address of the new interface using a sensible
		# algorithm to prevent conflicts on the network.
		#
		eiface_devid_a= eiface_devid_b=
		[ "$no_derive" ] || derive_mac -2 $iface "$name" \
			eiface_devid_a eiface_devid_b
		if [ "$eiface_devid_a" -a "$eiface_devid_b" ]; then
			ifconfig "e${i}a_$name" ether $eiface_devid_a
			ifconfig "e${i}b_$name" ether $eiface_devid_b
		fi > /dev/null 2>&1

		i=$(( $i + 1 ))
	done # for iface
}

jib_show_usage="show"
jib_show_descr="List possible NAME values for \`show NAME'"
jib_show1_usage="show NAME"
jib_show1_descr="Lists e0b_NAME [e1b_NAME ...]"
jib_show2_usage="show [NAME]"
jib_show()
{
	local OPTIND=1 OPTARG flag
	while getopts "" flag; do
		case "$flag" in
		*) action_usage show2 # NOTREACHED
		esac
	done
	shift $(( $OPTIND - 1 ))
	if [ $# -eq 0 ]; then
		ifconfig | awk '
			/^[^:[:space:]]+:/ {
				iface = $1
				sub(/:.*/, "", iface)
				next
			}
			$1 == "groups:" {
				for (n = split($0, group); n > 1; n--) {
					if (group[n] != "bridge") continue
					print iface
					next
				}
			}' |
			xargs -rn1 ifconfig |
			awk '$1 == "member:" &&
				sub(/^e[[:digit:]]+a_/, "", $2), $0 = $2' |
			sort -u
		return
	fi
	ifconfig | awk -v name="$1" '
		match($0, /^e[[:digit:]]+a_/) && sub(/:.*/, "") &&
			substr($1, RSTART + RLENGTH) == name
	' | sort
}

jib_destroy_usage="destroy NAME"
jib_destroy_descr="Destroy e0b_NAME [e1b_NAME ...]"
jib_destroy()
{
	local OPTIND=1 OPTARG flag
	while getopts "" flag; do
		case "$flag" in
		*) action_usage destroy # NOTREACHED
		esac
	done
	shift $(( $OPTIND -1 ))
	local name="$1"
	[ "${name:-x}" = "${name#*[!0-9a-zA-Z_]}" -a $# -eq 1 ] ||
		action_usage destroy # NOTREACHED
	mustberoot_to_continue
	jib_show "$name" | xargs -rn1 -I eiface ifconfig eiface destroy
}

############################################################ MAIN

#
# Command-line arguments
#
action="$1"
[ "$action" ] || usage # NOTREACHED

#
# Validate action argument
#
if [ "$BASH_VERSION" ]; then
	type="$( type -t "jib_$action" )" || usage # NOTREACHED
else
	type="$( type "jib_$action" 2> /dev/null )" || usage # NOTREACHED
fi
case "$type" in
*function)
	shift 1 # action
	eval "jib_$action" \"\$@\"
	;;
*) usage # NOTREACHED
esac

################################################################################
# END
################################################################################