#!/bin/bash
#
# .---.                  .              .
# |                      |              |
# |--- .--. .-.  .-.  .-.|  .-. .--.--. |.-.  .-. .--.  .-.
# |    |   (.-' (.-' (   | (   )|  |  | |   )(   )|  | (.-'
# '    '     --'  --'  -' -  -' '  '   -' -'   -' '   -  --'
#
#                    Freedom in the Cloud
#
# A script which recovers a user's gpg key from a number of fragments

# License
# =======
#
# Copyright (C) 2015-2018 Bob Mottram <bob@freedombone.net>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero 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 Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

PROJECT_NAME='freedombone'

export TEXTDOMAIN=${PROJECT_NAME}-recoverkey
export TEXTDOMAINDIR="/usr/share/locale"

source $PROJECT_INSTALL_DIR/${PROJECT_NAME}-vars

# include utils which allow function_check, go and drive mount
UTILS_FILES="/usr/share/${PROJECT_NAME}/utils/${PROJECT_NAME}-utils-*"
for f in $UTILS_FILES
do
    source "$f"
done

FRIENDS_SERVERS_LIST=
MY_USERNAME=

function show_help {
    echo ''
    echo $"${PROJECT_NAME}-recoverkey -u [username]"
    echo $'                           -l [friends servers list filename]'
    echo ''
    exit 0
}

while [ $# -gt 1 ]
do
    key="$1"

    case $key in
        -h|--help)
            show_help
            ;;
        -u|--user)
            shift
            MY_USERNAME="$1"
            ;;
        # backup list filename
        # typically /home/$USER/backup.list
        -l|--list)
            shift
            FRIENDS_SERVERS_LIST="$1"
            ;;
        *)
            # unknown option
            ;;
    esac
    shift
done

if [ ! "$MY_USERNAME" ]; then
    show_help
fi
if [ ! -d "/home/$MY_USERNAME" ]; then
    echo $"User $MY_USERNAME does not exist on the system"
    exit 7270
fi

if [ ! "$MY_USERNAME" ]; then
    echo $'No username given'
    exit 3578
fi
if [ ! -d "/home/$MY_USERNAME" ]; then
    echo $"User $MY_USERNAME does not exist on the system"
    exit 7270
fi

FRAGMENTS_DIR="/home/$MY_USERNAME/.gnupg_fragments"

# if no remote backup list was given then assume recover from USB
if [ ! "$FRIENDS_SERVERS_LIST" ]; then
    interactive_gpg_from_usb
    exit 0
fi

# obtain shares/fragments from remote locations
if [ "$FRIENDS_SERVERS_LIST" ]; then
    # For each remote server
    while read -r remote_server
    do
        # Get the server and its password
        # Format is:
        #   username@domain:/home/username <port number> <ssh password>
        REMOTE_SERVER=$(echo "${remote_server}" | awk -F ' ' '{print $1}')
        if [ "$REMOTE_SERVER" ]; then
            REMOTE_SSH_PORT=$(echo "${remote_server}" | awk -F ' ' '{print $2}')
            REMOTE_PASSWORD=$(echo "${remote_server}" | awk -F ' ' '{print $3}')

            # create a directory if it doesn't exist
            if [ ! -d "/home/$MY_USERNAME/.gnupg_fragments" ]; then
                mkdir -p "/home/$MY_USERNAME/.gnupg_fragments"
            fi

            echo -n $"Starting key retrieval from $REMOTE_SERVER..."
            /usr/bin/sshpass -p "$REMOTE_PASSWORD" \
                             scp -r -P "$REMOTE_SSH_PORT" "$REMOTE_SERVER/.gnupg_fragments/*" "/home/$MY_USERNAME/.gnupg_fragments"
            # shellcheck disable=SC2181
            if [ ! "$?" = "0" ]; then
                echo $'FAILED'
            else
                echo $'Ok'
            fi
        fi
    done < "$FRIENDS_SERVERS_LIST"
fi

# was a directory created?
if [ ! -d "$FRAGMENTS_DIR" ]; then
    echo $'No fragments have been recovered, so the key cannot be recovered'
    exit 7483
fi

# was anything downloaded?
cd "$FRAGMENTS_DIR" || exit 24682468
# shellcheck disable=SC2012
no_of_shares=$(ls -afq keyshare.asc.* | wc -l)
if (( no_of_shares == 0 )); then
    echo $'No key fragments were retrieved'
    exit 76882
fi

# set permissions on the fragments
chown -R "$MY_USERNAME":"$MY_USERNAME" "/home/$MY_USERNAME/.gnupg_fragments"

# decrypt the file
KEYS_FILE=$FRAGMENTS_DIR/keyshare.asc
cd "$FRAGMENTS_DIR" || exit 482746874624
gfcombine "$KEYS_FILE.*"

if [ ! -f "$KEYS_FILE" ]; then
    echo $'Unable to decrypt key. This may mean that not enough fragments are available'
    exit 6283
fi

echo $'Key fragments recombined'

# import the gpg key
if ! gpg --homedir="/home/$MY_USERNAME/.gnupg" --allow-secret-key-import --import "$KEYS_FILE"; then
    echo $'Unable to import gpg key'
    shred -zu "$KEYS_FILE"
    exit 3682
fi
shred -zu "$KEYS_FILE"
chown -R "$MY_USERNAME":"$MY_USERNAME" "/home/$MY_USERNAME/.gnupg"
chmod -R 600 "/home/$MY_USERNAME/.gnupg"

echo $'GPG key was recovered'

exit 0