#!/bin/bash


# Configure sSMTP.
#	Intended primarily for use with a frequently varying
#	host address and name, typically a PPP link.


# Usage: ssmtp-ppp-config [ option ... ]
#	-v						Be verbose
#	-p						Use current PPP host name (default)
#	-d						Use default local host name from
#							  \"\$PROJ_ETC/localHost\" (\"$PROJ_ETC/localHost\")
#	-h localHost			Specify the local host name
#	-m mailHost				Specify mail delivery host name
#	-fy | -foy | -floy		Allow From: override from message header
#	-fn | -fon | -flon		Forbid From: override from message header
#	-h | -help | --help		Display this usage summary


usageSummary="Usage: ssmtp-ppp-config [ option ... ]
#   -v                      Be verbose
#   -p                      Use current PPP host name (default)
#   -d                      Use default local host name from
#                             \"\$PROJ_ETC/localHost\" (\"$PROJ_ETC/localHost\")
#   -h localHost            Specify the local host name
#   -m mailHost             Specify mail delivery host name
#   -fy | -foy | -floy      Allow From: override from message header
#   -fn | -fon | -flon      Forbid From: override from message header
#   -h | -help | --help     Display this usage summary
"

showUsage() {
	echo -n "ssmtp-ppp-config: "
	echo "$usageSummary"
}


localHost=
mailHost=
fromOverride="FromLineOverride=YES"
flo=

operateQuietly=1
quitEarly=


# Process arguments
while [ $# -gt 0 ]; do
	arg="$1"
	shift

	case "$arg" in
	-v)
		operateQuietly=
		;;

	-p)
		localHost=
		;;

	-d)
		checkenv PROJ_ETC || exit 1
		if [ ! -s "$PROJ_ETC/localhost" ]; then
			localHost="$(cat "$PROJ_ETC/localHost")"
		else
			echo "ssmtp-ppp-config: Error: \"$RPOJ_ETC/localhost\" does not exist or is empty." >&2
			quitEarly=1
		fi
		;;

	-m)
		mailHost="$1"
		shift
		;;

	-h)
		localHost="$1"
		shift
		;;

	-fy | -foy | -floy)
		flo=1
		fromOverride="FromLineOverride=YES"
		;;

	-fn | -fon | -flon)
		flo=0
		fromOverride="FromLineOverride=NO"
		;;

	-h | -help | --help)
		showUsage
		quitEarly=0
		;;
	esac
done



# If not specified, use the local PPP host name as the local host name
if [ -z "$localHost" ]; then
	localHost="${2:-$(pppDNS)}"

	if [ -z "$localHost" ]; then
		echo "ssmtp-ppp-config: Cannot ascertain local host name"
		quitEarly=1
	fi
fi


# If not specified, use the default mail hub name
if [ -z "$mailHost" ]; then
	checkenv PROJ_ETC || exit 1

	if [ -s "$PROJ_ETC/mailhost" ]; then
		. "$PROJ_ETC/mailhost"
	else
		echo "No outgoing mail host information available" >&2
		quitEarly=1
	fi
fi


if [ "$quitEarly" ]; then
	exit $quitEarly
fi



if [ ! "$operateQuietly" ]; then
	echo "Using mail delivery host \"$mailHost\" and local host name \"$localHost\""
	[ "$flo" ] && echo "From-line override allowed" || echo "From-line override forbidden"
fi


#
# Generate the ssmtp configuration file
#

cat >|"/etc/ssmtp/ssmtp.conf" <<-EOCONFIG
	#
	# /etc/ssmtp.conf -- a config file for sSMTP sendmail.
	#

	# The person who gets all mail for userids < 10
	root=postmaster

	# The place where the mail goes. The actual machine name is required
	# no MX records are consulted. Commonly mailhosts are named mail.domain.com
	# The example will fit if you are in domain.com and you mailhub is so named.
	mailhub=$mailHost

	# Where will the mail seem to come from?
	#rewriteDomain=$mailname
	# The full hostname
	hostname=$localHost

	# Set this to never rewrite the "From:" line (unless not given) and to
	# use that address in the "from line" of the envelope.
	$fromOverride
EOCONFIG