#!/bin/bash

set -e$MODRELAYS_PROBE_SET_X

MODRELAYS=moderators.isc.org
PROBE_TIMEOUT=$(( 20 * 60 ))
PROBE_EXPIRE=$(( 32 * 86400 ))

. ../global-settings
. ./settings

id=$(date +%s)_$$
statedir=probes/probes
lockfile=$statedir/.lock

fail () {
	printf >&2 "%s\n" "modrelays-probe: error: $1"
	exit 16
}

record-probing () {
	# implicitly uses newsgroup, id, domain
	# caller must "local td", which will be set
	local probeid=$1

	probeid="$domain,${probeid//[^-=.,_0-9A-Za-z]/%/},$id"
	case $probeid in
	.*|*/*) fail "yikes, sanitisation bug!" ;;
	esac

	td="$statedir/$probeid"
	mkdir -p $td
}

record-probing-start () {
	record-probing "$@"
	if ! [ -e "$td/started" ]; then
		date -R >"$td/started"
	fi
}

record-outcome () {
	local probeid=$1
	local outcome=$2
	local message=$3
	local td
	record-probing "$probeid"
	printf "%s\n" >"$td"/"$outcome" "$message"
}

record-success () { record-outcome "$1" ok ''; }
record-tempfail () { record-outcome "$1" tempfail "$2"; }
record-permfail () { record-outcome "$1" permfail "$2"; }

probe-addr () {
	local mx=$1
	local addr=$2

	local td
	record-probing-start "mx=$mx,addr=$addr"

	set +e
	swaks	--to "${GROUP//./-}@$domain" \
		--server $addr \
		--tls-optional-strict \
		--header 'Subject: test modrelays probe test' \
		--header \
	"X-WebSTUMP-Relay-Probe: $GROUP $id $domain $mx $addr" \
		-n >$td/swaks.log 2>$td/swaks.err
	rc=$?
	set -e

	case $rc in
	0) return ;; # record-success done by receiver
	esac
	local permfail=''

	local rhs
	local prefix
	local expect_no_5xx='initial connection'
	exec 4<$td/swaks.log
	while read <&4 prefix rhs; do
		case "$prefix" in
		'<'*)
			case "$rhs" in
			5*)
				if [ "x$expect_no_5xx" != x ] && \
				   [ "x$permfail" = x ]; then
					permfail="$rhs ($expect_no_5xx)"
				fi
				;;
			esac
			;;
		*'>')
			case "$rhs" in
			EHLO*|STARTTLS*) expect_no_5xx='' ;;
			*) expect_no_5xx="after $rhs" ;;
			esac
			;;
		*)
		esac
	done

	if [ "x$permfail" = x ]; then
		record-tempfail "mx=$mx,addr=$addr" "see swaks.log / swaks.err"
	else
		record-permfail "mx=$mx,addr=$addr" "$permfail"
	fi
}

probe-domain () {
	local domain=$1
	local td
	record-probing-start dns
	
	set +e
	adnshost -Fi -Tn +Do +Dt -t mx $domain >$td/dns
	rc=$?
	set -e

	case $rc in
	0)
		# have a list of MX's
		exec 3<$td/dns
		local pref
		local mx
		local statustype
		local rhs
		while read <&3 pref mx statustype statustypenum rhs; do
			case $statustypenum in
			0)
				# have a list of relays
				case $rhs in
				*" ( "*")") ;;
				*)
					record-permfail "mx=$mx" \
						"dns format $rhs"
					continue
					;;
				esac
				rhs=${rhs##* (}
				rhs=${rhs% )}
				local addr
				for addr in $rhs; do
					case $addr in
					INET|INET6) continue ;;
					esac
					probe-addr $mx $addr
				done
				;;
			[123])
				# temporary errors
				record-tempfail "mx=$mx" \
					"dns $rc $statustype $rhs"
				;;
			*)
				# yikes
				record-permfail "mx=$mx" \
					"dns $rc $statustype $rhs"
				;;
			esac
		done
		record-success dns
		return
		;;
	6)
		# permfail, try A
		set +e
		adnshost -Fi -Tn +Do +Dt -t a $domain >$td/dns
		rc=$?
		set -e
		;;
	esac

	case $rc in
	0)
		# have a list of A's (dealt with MXs above)
		exec 3<$td/dns
		local addr
		while read <&3 addr; do
			probe-addr 'NONE' $addr
		done
		record-success dns
		return
		;;
	[123])
		local emsg
		read <$td/dns emsg
		record-tempfail dns "dns <no-mx> $emsg"
		;;
	*)
		local emsg
		read <$td/dns emsg
		record-permfail dns "dns <no-mx> $emsg"
		;;
	esac
}

no_args () {
	case $1 in
	0) return ;;
	*) fail "no arguments to $mode allowed" ;;
	esac
}

acquire_lock () {
	local lock_mode="$1"
	if [ x"$WEBSTUMP_PROBE_LOCK" = x"$lockfile" ]; then return; fi
	WEBSTUMP_PROBE_LOCK=$lockfile \
	exec with-lock-ex $lock_mode "$lockfile" "$0" "$mode" "$@"
}

maybe-report () {
	local outcome=$1

	if $found_to_report; then return; fi
	if ! [ -e "$attempt/$outcome" ]; then return; fi
	found_to_report=true

	read <"$attempt/$outcome" message

	local reported
	if [ -e "$attempt/reported" ]; then
		read <"$attempt/reported" reported
	fi
	if [ "x$outcome" = "x$reported" ]; then return; fi

	if [ x"$outcome" = x"ok" ] && [ x"$reported" = x ]; then
		echo ok >"$attempt/reported"
		return
	fi

	local info=${attempt##*/}
	info=${info//,/ }

	delim=`od -N 50 -An -x -w50 </dev/urandom`
	delim=${delim// /}

	local email="$attempt/.report.$outcome"
	cat >"$email" <<END
To: $ADMIN
Subject: mod relay probe $outcome $info
Content-Type: multipart/mixed; boundary="$delim"
MIME-Version: 1.0

--$delim
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: 7bit

The moderation relay probe
  $info
END

	if [ -e "$attempt/started" ]; then
		local started
		read started <"$attempt/started"
		cat >>"$email" <<END
started at
  $started
END
	fi

	cat >>"$email" <<END
resulted in the outcome
  $outcome
END
	if [ "x$message" != x ]; then
		cat >>"$email" <<END
with the message
  $message
END
	fi

	if [ "x$reported" != x ]; then
		cat >>"$email" <<END
This is even though previously the outcome seemed to be
  $reported
and this was reported previously.
END
	fi

	cat >>"$email" <<END

Logs are in
  $attempt
and concatenated to this email.

END

	local log
	for log in "$attempt"/*; do
		cat >>"$email" <<END
--$delim
Content-Type: text/plain; charset="utf-8"
Content-Disposition: inline; filename="${log##*/}"
Content-Description: "${log##*/}"
Content-Transfer-Encoding: 8bit

END
		cat >>"$email" <"$log"
		echo >>"$email"
	done

	cat >>"$email" <<END
--$delim--
END

	/usr/sbin/sendmail -odb -oem -oee -t <"$email"
	echo "$outcome" >"$attempt"/reported
}

mode_report () {
	acquire_lock -w "$@"

	local attempt
	for attempt in $statedir/*; do

		local now=$(date +%s)
		local age=$(stat -c %Y "$attempt")
		age=$(( $now - $age ))

		local found_to_report=false
		maybe-report ok
		maybe-report permfail
		maybe-report tempfail

		if ! [ -e $attempt/reported ] && \
		     [ $age -gt $PROBE_TIMEOUT ]; then
			echo >"$attempt"/timeout \
	"Message did not arrive after ${PROBE_TIMEOUT}s"
		fi

		maybe-report timeout

		if [ -e $attempt/reported ] && \
		   [ $age -gt $PROBE_EXPIRE ]; then
			rm -rf "$attempt"
		fi
	done
}

mode_all () {
	no_args $#
	for domain in $MODRELAYS; do
		probe-domain $domain
	done
}

mode_auto () {
	no_args $#
	xxx do something to cause sleeping
	mode_all
}

mode_domain () {
	for domain in "$@"; do
		probe-domain $domain
	done
}

mode=$1; shift||:

"mode_$mode" "$@"