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

# License
# =======
#
# Copyright (C) 2015 Bob Mottram <bob@robotics.uk.to>
#
# 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/>.

FRIENDS_SERVERS_LIST=
MY_USERNAME=

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

while [[ $# > 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

# find the remote backup list
if [ ! $FRIENDS_SERVERS_LIST ]; then
    if [ -f /home/$MY_USERNAME/backup.list ]; then
        FRIENDS_SERVERS_LIST=/home/$MY_USERNAME/backup.list
    fi
fi

# obtain shares/fragments from remote locations
if [ $FRIENDS_SERVERS_LIST ]; then
    # For each remote server
    while read remote_server
    do
        # Get the server and its password
        # Format is:
        #   username@domain:/home/username <port number> <ssh password>
        REMOTE_SERVER=$(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
            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 $FRAGMENTS_DIR
no_of_shares=$(ls -afq keyshare.asc.* | wc -l)
no_of_shares=$((no_of_shares - 2))
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
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
su -c "gpg --allow-secret-key-import --import $KEYS_FILE" - $MY_USERNAME
if [ ! "$?" = "0" ]; 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