Get the CRAM-MD5 authentication response

axmd5

#!/usr/bin/env bash
usage() {

	echo "$0 [-g] [-p] [challenge]" >&2
	echo " -g: Generate a new password and create or update ~/.bcpasswd" >&2
	echo " -p: Ignore ~/.bcpasswd and ask for the password to use." >&2
	exit 2
}

prompt_password() {
	read -sp "Password: " password
	echo ""
}

ask_password=0
gen_password=0
bcpasswd_loc=~/.bcpasswd

while [ $# -ne 0 ]; do
	case "$1" in
		-g) gen_password=1; shift ;;
		-p) ask_password=1; shift ;;
		--) shift; break ;;
		-*)  echo "Unknown option: $1" >&2; usage ;;
		*)
			if [[ -z "${challenge}" ]]; then
				challenge="$1"
			else
				echo "Unexpected extra argument: $1" >&2
				usage
			fi
			shift
			;;
	esac
done

if [ ${ask_password} -ne 0 ]; then
	prompt_password

elif [ ${gen_password} -ne 0 ]; then
	password=$(cat /dev/urandom | tr -dc '(-9<-[]-{' | fold -w 32 | head -n 1)
	if [ -f "${bcpasswd_loc}" ]; then
		sed -i '/^md5:/d' "${bcpasswd_loc}"
	else
		touch "${bcpasswd_loc}"
		chmod 600 "${bcpasswd_loc}"
		echo "md5:${password}" >> "${bcpasswd_loc}"
	fi
	exit 0

else
	if [ -r "${bcpasswd_loc}" ]; then
		passline=$(grep '^md5:' "${bcpasswd_loc}")
		retcode=$?
		n_lines=$(echo "${passline}" | wc -l)
		if [ ${retcode} -eq 0 ] && [ ${n_lines} -eq 1 ]; then
			password=$(echo "${passline}" | sed -e 's/^md5://' -e 's/^\s\+//' )
		else
			echo "Malformed '${bcpasswd_loc}' file."
		fi
	fi
fi

if [ -z "${password}" ]; then prompt_password; fi
if [ -z "${challenge}" ]; then read -p "Challenge: " challenge; fi

echo -ne "Response: "
echo -ne "${challenge}${password}" | md5sum | awk '{print $1;}'