#!/bin/bash

# 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"`[$$]"
BASEDIR="/srv/static.debian.org"
COMPONENTLIST=/etc/static-components.conf

usage() {
	echo "local Usage: $0 <host>"
	echo "via ssh orig command:"
	echo "                      mirror <component> <serial>"
	echo "                      rsync <stuff>"
	echo "                      static-master-update-component <component>"
}

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 remote_host="$1"; shift
	one_more_arg "$@"
	local component="$1"; shift
	one_more_arg "$@"
	local serial="$1"; shift

	masterhost="$(awk -v component="$component" '!/^ *(#|$)/ && $2 == component {print $1; exit}' "$COMPONENTLIST")"
	if [ -z "$masterhost" ]; then
		croak "Did not find master for component $component."
	elif [ "$masterhost" != "$remote_host" ]; then
		croak "$remote_host is not master for $component."
	else
		info "Host $remote_host triggered a mirror run for $component, serial $serial"
		exec /usr/local/bin/static-mirror-run "$BASEDIR/mirrors/$component" "$remote_host:$component/-new-" "$serial"
		echo >&2 "Exec failed"
		croak "exec failed"
	fi
}

do_rsync_on_master() {
	local remote_host="$1"; shift
	local allowed_rsyncs
	allowed_rsyncs=()
	allowed_rsyncs+=("--server --sender -vlHtrze.iLsf --safe-links .") # wheezy
	allowed_rsyncs+=("--server --sender -vlHtrze.iLsfx --safe-links .") # jessie

	for cmd_idx in ${!allowed_rsyncs[*]}; do
		args="${allowed_rsyncs[$cmd_idx]}"
		for component in $(awk -v this_host="$(hostname -f)" '!/^ *(#|$)/ && $1 == this_host {print $2}' $COMPONENTLIST); do
			if [ "$*" = "$args $component/-new-/" ] || [ "$*" = "$args ./$component/-new-/" ] ; then
				local path="$BASEDIR/master/$component-current-push"
				info "serving $remote_host with $path"
				exec rsync $args "$path/."
				croak "Exec failed"
			elif [ "$*" = "$args $component/-live-/" ] || [ "$*" = "$args ./$component/-live-/" ] ; then
				local path="$BASEDIR/master/$component-current-live"
				info "host $remote_host wants $path, acquiring lock"
				exec 200< "$path"
				if ! flock -s -w 0 200; then
				echo >&2 "Cannot acquire shared lock on $path - this should mean an update is already underway anyway."
				exit 1
				fi
				exec rsync $args "$path/."
				croak "Exec failed"
			fi
		done
	done
}

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

	local allowed_rsyncs
	allowed_rsyncs=()

	if [ -e "$COMPONENTLIST" ]; then
		for path in $(awk -v host="$(hostname -f)" '!/^ *(#|$)/ && $3 == host {print $4}' $COMPONENTLIST); do
			allowed_rsyncs+=("--server --sender -lHtrze.iLsf --safe-links . $path/.") # wheezy
			allowed_rsyncs+=("--server --sender -lHtrze.iLsfx --safe-links . $path/.") # jessie
		done
	fi
	for cmd_idx in ${!allowed_rsyncs[*]}; do
		allowed="${allowed_rsyncs[$cmd_idx]}"
		if [ "$*" = "$allowed" ]; then
			info "Running for host $remote_host: rsync $*"
			exec rsync "$@"
			croak "Exec failed"
		fi
	done
}

do_rsync() {
	do_rsync_on_master "$@"
	do_rsync_on_source "$@"

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

do_update_component() {
	local remote_host="$1"; shift

	one_more_arg "$@"
	component="$1"
	shift

	hit="$(
		awk -v this_host="$(hostname -f)" -v component="$component" -v host="$remote_host" '
			!/^ *(#|$)/ && $1 == this_host && $2 == component {
				if ($3 == host) {
					print $4
					exit
				}
				split($5,extra,",")
				for (i in extra) {
					if (host == extra[i]) {
						printf "%s:%s\n", $3, $4
						exit
					}
				}
				exit
			}' "$COMPONENTLIST"
		)"
	if [ -n "$hit" ]; then
		exec static-master-update-component "$component"
		echo >&2 "Exec failed"
		croak "exec failed"
	else
		info "Not whitelisted: $remote_host update $component"
		echo >&2 "Not whitelisted: $remote_host update $component"
		exit 1
	fi
}


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

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

info "host $remote_host called with $*"

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

case "$action" in
	# on a static mirror, update a component from its master
	mirror)
		do_mirror "$remote_host" "$@"
		;;
	# on a static source, allow fetching from the master,
	# on a master, allow fetching from a component's mirrors
	rsync)
		do_rsync "$remote_host" "$@"
		;;
	# on a master, initiate an update of a component
	static-master-update-component)
		do_update_component "$remote_host" "$@"
		;;
	*)
		croak "Invalid operation '$action'"
		;;
esac