#!/bin/bash

# This is a wrapper script for ssh access on Debian's static mirroring infrastructure.
#
# It limits the commands the master can run on static-mirroring mirrors (i.e.
# the things running apache) on one hand, and also on static-mirroring sources,
# that is the things that create the data.

# Copyright (c) 2009, 2010, 2012 Peter Palfrader
#
# 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 THE AUTHORS OR COPYRIGHT HOLDERS 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.

set -e
set -u

MYLOGNAME="`basename "$0"`[$$]"
COMPONENTLIST=/etc/static-components.conf

usage() {
	echo "local Usage: $0 <basedir> <host>"
	echo "via ssh orig command:"
	echo "                      mirror <serial>"
}

one_more_arg() {
	if [ "$#" -lt 1 ]; then
		usage >&2
		exit 1
	fi
}

info() {
	logger -p daemon.info -t "$MYLOGNAME" "$1"
}

croak() {
	logger -s -p daemon.warn -t "$MYLOGNAME" "$1"
	exit 1
}

do_mirror() {
	local basedir="$1"; shift
	local remote_host="$1"; shift
	one_more_arg "$@"
	local serial="$1"; shift

	info "Host $remote_host triggered a mirror run for serial $serial"
	exec /usr/local/bin/static-mirror-run "$basedir" "$remote_host:-new-" "$serial"
	echo >&2 "Exec failed"
	croak "exec failed"
}

do_rsync() {
	local remote_host="$1"
	shift

	local allowed_rsyncs
	allowed_rsyncs=()

	if [ -e "$COMPONENTLIST" ]; then
		for path in $(awk -v host="$(hostname -f)" '$2 == host {print $3}' $COMPONENTLIST); do
			allowed_rsyncs+=("--server --sender -lHtrze.iLsf --safe-links . $path/.")
		done
	fi
	for cmd_idx in ${!allowed_rsyncs[*]}; do
		allowed="${allowed_rsyncs[$cmd_idx]}"
		if [ "$*" = "$allowed" ]; then
			info "Running for host $remote_host: rsync $*"
			exec rsync "$@"
			echo >&2 "Exec failed"
			exit 1
		fi
	done

	info "NOT allowed for $remote_host: rsync $*"
	echo >&2 "This rsync command ($*) not allowed."
	exit 1
}


if [ "${1:-}" = "-h" ] || [ "${1:-}" = "--help" ]; then
	usage
	exit 0
fi

one_more_arg "$@"
basedir="$1"
shift

one_more_arg "$@"
remote_host="$1"
shift


# check/parse remote command line
if [ -z "${SSH_ORIGINAL_COMMAND:-}" ] ; then
	croak "Did not find SSH_ORIGINAL_COMMAND"
fi
set "dummy" ${SSH_ORIGINAL_COMMAND}
shift

one_more_arg "$@"
action="$1"
shift

case "$action" in
	mirror)
		do_mirror "$basedir" "$remote_host" "$@"
		;;
	rsync)
		do_rsync "$remote_host" "$@"
		;;
	*)
		croak "Invalid operation '$action'"
		;;
esac