#!/bin/bash -e
# vim: set tabstop=8 shiftwidth=4 softtabstop=4 expandtab smarttab colorcolumn=80:
#
# Copyright (c) 2017 Red Hat, Inc.
# Author: Nathaniel McCallum <npmccallum@redhat.com>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

[ $# -eq 1 -a "$1" == "--summary" ] && exit 1

if [ -t 0 ]; then
    echo >&2
    echo "Usage: clevis decrypt http < JWE > PLAINTEXT" >&2
    echo >&2
    exit 1
fi

read -d . hdr

if [ "`jose fmt -q "$hdr" -SyOg clevis -g pin -u-`" != "http" ]; then
    echo "JWE pin mismatch!" >&2
    exit 1
fi

if ! url=`jose fmt -q "$hdr" -SyOg clevis -g http -g url -u-`; then
    echo "JWE missing 'clevis.http.url' header parameter!" >&2
    exit 1
fi

if ! typ=`jose fmt -q "$hdr" -SyOg clevis -g http -g type -u-`; then
    echo "JWE missing 'clevis.http.url' header parameter!" >&2
    exit 1
fi

if ! rep=`curl -sfg -H "Accept: $typ" "$url"`; then
    echo "Key transfer failed!" >&2
    exit 1
fi

case $typ in
application/jwk+json)
    if ! rep=`curl -sfg -H "Accept: $typ" "$url" \
            | jose fmt -j- -Og kty -q oct -EUUo-`; then
        echo "Key transfer failed!" >&2
        exit 1
    fi
    ;;
application/octet-stream)
    if ! key=`curl -sfg -H "Accept: $typ" "$url" | jose b64 enc -I-`; then
        echo "Key transfer failed!" >&2
        exit 1
    fi
    jwk="{\"kty\":\"oct\",\"k\":\"$key\"}"
    ;;
esac

exec jose jwe dec -k- -i- < <(echo -n "$jwk$hdr."; cat)