#!/bin/bash
#  _____               _           _
# |   __|___ ___ ___ _| |___ _____| |_ ___ ___ ___
# |   __|  _| -_| -_| . | . |     | . | . |   | -_|
# |__|  |_| |___|___|___|___|_|_|_|___|___|_|_|___|
#
#                              Freedom in the Cloud
#
# This is an optional command for setting up a client machine
# to then be able to log into a server. It installs a few packages
# for things like IRC and twiddles crypto settings.
#
# It may not be necessary to run this on client machines, and
# is provided for some extra convenience on a Debian or Arch
# based system.
#
# 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}-client
export TEXTDOMAINDIR="/usr/share/locale"

CURR_USER=$USER
CURR_GROUP=$USER
if [ -f /usr/bin/pacman ]; then
    CURR_GROUP='users'
fi

# setup for a specific app
SETUP_CLIENT_APP_NAME=

# Version number of this script
VERSION="3.1"

# get the main project file, so that some values can be extracted
MAIN_PROJECT_FILE=/usr/local/bin/${PROJECT_NAME}
if [ ! -f $MAIN_PROJECT_FILE ]; then
    MAIN_PROJECT_FILE=/usr/bin/${PROJECT_NAME}
fi
if [ ! -f $MAIN_PROJECT_FILE ]; then
    echo "The main project file $MAIN_PROJECT_FILE was not found"
    exit 72529
fi

# ssh (from https://stribika.github.io/2015/01/04/secure-secure-shell.html)
UTILS_SSH="/usr/share/${PROJECT_NAME}/utils/${PROJECT_NAME}-utils-ssh"
SSH_CIPHERS=$(grep 'SSH_CIPHERS=' "$UTILS_SSH" | head -n 1 | awk -F '"' '{print $2}')
SSH_MACS=$(grep 'SSH_MACS=' "$UTILS_SSH" | head -n 1 | awk -F '"' '{print $2}')
SSH_KEX=$(grep 'SSH_KEX=' "$UTILS_SSH" | head -n 1 | awk -F '"' '{print $2}')
SSH_HOST_KEY_ALGORITHMS=$(grep 'SSH_HOST_KEY_ALGORITHMS=' "$UTILS_SSH" | head -n 1 | awk -F '"' '{print $2}')

# refresh gpg keys every few hours
REFRESH_GPG_KEYS_HOURS=2

function global_rate_limit {
    SYSCTL_FILE=/etc/sysctl.conf
    if [ -f /usr/bin/pacman ]; then
        SYSCTL_FILE=/etc/sysctl.d/99-sysctl.conf
    fi
    if [ ! -f $SYSCTL_FILE ]; then
        sudo touch $SYSCTL_FILE
    fi

    sudo cp $SYSCTL_FILE ~/sysctl.conf
    sudo chown "$CURR_USER":"$CURR_GROUP" ~/sysctl.conf
    if ! grep -q "tcp_challenge_ack_limit" ~/sysctl.conf; then
        echo 'net.ipv4.tcp_challenge_ack_limit = 999999999' >> ~/sysctl.conf
    else
        sed -i 's|net.ipv4.tcp_challenge_ack_limit.*|net.ipv4.tcp_challenge_ack_limit = 999999999|g' ~/sysctl.conf
    fi
    sudo cp ~/sysctl.conf $SYSCTL_FILE
    sudo rm ~/sysctl.conf
    sudo sysctl -p -q $SYSCTL_FILE
}

function refresh_gpg_keys {
    if [ ! -f /usr/bin/gpg ]; then
        if [ ! -f /usr/bin/pacman ]; then
            sudo apt-get -yq install gnupg
        else
            sudo pacman -S --noconfirm gnupg
        fi
    fi
    sudo cp /etc/crontab ~/temp_crontab
    if [ -f ~/temp_crontab ]; then
        sudo chown "$CURR_USER":"$CURR_GROUP" ~/temp_crontab
        if grep -q 'test' ~/temp_crontab; then
            if ! grep -q 'gpg --refresh-keys' ~/temp_crontab; then
                echo "0            */$REFRESH_GPG_KEYS_HOURS *   *   *   $CURR_USER /usr/bin/gpg --refresh-keys > /dev/null" >> ~/temp_crontab
                sudo cp ~/temp_crontab /etc/crontab
                sudo chown root:root /etc/crontab
            fi
        fi
        rm ~/temp_crontab
    fi
}

# see https://stribika.github.io/2015/01/04/secure-secure-shell.html
function ssh_remove_small_moduli {
    # shellcheck disable=SC2024
    sudo awk '$5 > 2000' /etc/ssh/moduli > "/home/$CURR_USER/moduli"
    # shellcheck disable=SC2086
    sudo mv /home/$CURR_USER/moduli /etc/ssh/moduli
}

function configure_ssh_client {
    if [ -f /usr/bin/pacman ]; then
        sudo pacman --noconfirm -S openbsd-netcat
    else
        sudo apt-get -yq install tor connect-proxy vim-common
    fi

    #sudo sed -i 's/#   PasswordAuthentication.*/   PasswordAuthentication no/g' /etc/ssh/ssh_config
    #sudo sed -i 's/#   ChallengeResponseAuthentication.*/   ChallengeResponseAuthentication no/g' /etc/ssh/ssh_config
    sudo sed -i "s/#   HostKeyAlgorithms.*/   HostKeyAlgorithms $SSH_HOST_KEY_ALGORITHMS/g" /etc/ssh/ssh_config
    sudo sed -i "s/#   Ciphers.*/   Ciphers $SSH_CIPHERS/g" /etc/ssh/ssh_config
    sudo sed -i "s/#   MACs.*/   MACs $SSH_MACS/g" /etc/ssh/ssh_config
    sudo sed -i "s/HostKeyAlgorithms.*/HostKeyAlgorithms $SSH_HOST_KEY_ALGORITHMS/g" /etc/ssh/ssh_config
    if ! grep -q "HostKeyAlgorithms" /etc/ssh/ssh_config; then
        sudo cp /etc/ssh/ssh_config ~/ssh_config
        sudo chown "$CURR_USER":"$CURR_GROUP" ~/ssh_config
        echo "   HostKeyAlgorithms $SSH_HOST_KEY_ALGORITHMS" >> ~/ssh_config
        sudo mv ~/ssh_config /etc/ssh/ssh_config
        sudo chown root:root /etc/ssh/ssh_config
    fi
    sudo sed -i "s/HostKeyAlgorithms.*/#HostKeyAlgorithms $SSH_HOST_KEY_ALGORITHMS/g" /etc/ssh/ssh_config

    sudo sed -i "s/Ciphers.*/Ciphers $SSH_CIPHERS/g" /etc/ssh/ssh_config
    if ! grep -q "Ciphers " /etc/ssh/ssh_config; then
        sudo cp /etc/ssh/ssh_config ~/ssh_config
        sudo chown "$CURR_USER":"$CURR_GROUP" ~/ssh_config
        echo "   Ciphers $SSH_CIPHERS" >> ~/ssh_config
        sudo mv ~/ssh_config /etc/ssh/ssh_config
        sudo chown root:root /etc/ssh/ssh_config
    fi
    sudo sed -i "s/MACs.*/MACs $SSH_MACS/g" /etc/ssh/ssh_config
    if ! grep -q "MACs " /etc/ssh/ssh_config; then
        sudo cp /etc/ssh/ssh_config ~/ssh_config
        sudo chown "$CURR_USER":"$CURR_GROUP" ~/ssh_config
        echo "   MACs $SSH_MACS" >> ~/ssh_config
        sudo mv ~/ssh_config /etc/ssh/ssh_config
        sudo chown root:root /etc/ssh/ssh_config
    fi

    # Create ssh keys
    if [ ! -f "/home/$CURR_USER/.ssh/id_ed25519" ]; then
        ssh-keygen -t ed25519 -o -a 100
    fi
    if [ ! -f "/home/$CURR_USER/.ssh/id_rsa" ]; then
        ssh-keygen -t rsa -b 2048 -o -a 100
    fi

    ssh_remove_small_moduli

    if [ ! -d ~/.ssh ]; then
        mkdir ~/.ssh
    fi
    if [ ! -f ~/.ssh/config ]; then
        touch ~/.ssh/config
    fi
    proxycmd="connect -R remote -5 -S 127.0.0.1:9050 %h %p"
    if [ -f /usr/bin/pacman ]; then
        proxycmd="/usr/bin/nc -X 5 -x 127.0.0.1:9050 %h %p"
    fi
    if ! grep -q "# ${PROJECT_NAME} settings" ~/.ssh/config; then
        if ! grep -q 'ProxyCommand' ~/.ssh/config; then
            { echo "# ${PROJECT_NAME} settings start";
              echo 'Host *.onion';
              echo '  ServerAliveInterval 60';
              echo '  ServerAliveCountMax 3';
              echo "  ProxyCommand $proxycmd";
              echo 'Host *';
              echo '  ServerAliveInterval 60';
              echo '  ServerAliveCountMax 3';
              echo "# ${PROJECT_NAME} settings end"; } >> ~/.ssh/config
        fi
    fi

    echo ''
    echo $'Go to the Administrator Control Panel, select "Manage Users", '
    echo $'"Change user ssh public key" then "yes" and paste the following:'
    echo ''
    cat "/home/$CURR_USER/.ssh/id_rsa.pub"
    cat "/home/$CURR_USER/.ssh/id_ed25519.pub"
    echo ''
    echo $'Then go to "Security Settings", select "Allow ssh login with passwords"'
    echo $'and set it to "no".'
}

function show_help {
    echo ''
    echo $"${PROJECT_NAME}-client"
    echo ''
    exit 0
}

function setup_client_app_irc {
    echo $'Setting up hexchat'
    if [ ! -f /usr/bin/pacman ]; then
        sudo apt-get -yq install tor hexchat tor
    else
        sudo pacman -S --noconfirm hexchat tor
    fi
    if [ ! -d "/home/$CURR_USER/.config/hexchat" ]; then
        mkdir -p "/home/$CURR_USER/.config/hexchat"
    fi
    { echo 'net_proxy_host = 127.0.0.1';
      echo 'net_proxy_port = 9050';
      echo 'net_proxy_type = 3';
      echo 'net_proxy_use = 0';

      echo 'net_proxy_auth = 1';
      echo 'net_proxy_pass = HexChat';
      echo 'net_proxy_user = HexChat';

      echo 'dcc_auto_chat = 0';
      echo 'dcc_auto_resume = 0';
      echo 'dcc_auto_send = 0';
      echo 'irc_hide_version = 1';
      echo 'identd = 0';

      echo 'away_reason =';
      echo 'irc_part_reason =';
      echo 'irc_quit_reason =';

      echo "irc_real_name = ${USER}";
      echo "irc_user_name = ${USER}";
      echo "irc_nick1 = ${USER}";
      echo "irc_nick2 = ${USER}_";
      echo "irc_nick3 = ${USER}__";

      echo 'completion_suffix = :';

      echo 'gui_slist_skip = 1'; } > "/home/$CURR_USER/.config/hexchat/hexchat.conf"

    echo $'hexchat configured'
}

function setup_client_app {
    if [ ! $SETUP_CLIENT_APP_NAME ]; then
        return
    fi

    case $SETUP_CLIENT_APP_NAME in
        hexchat|xchat|irc)
            setup_client_app_irc
            ;;
    esac
    exit 0
}

function remove_known_hosts_entries {
    # remove any previous freedombone entries from known hosts
    if [ -f "/home/$CURR_USER/.ssh/known_hosts" ]; then
        sed -i "/${PROJECT_NAME}.local/d" "/home/$CURR_USER/.ssh/known_hosts"
    fi
}

function setup_avahi_client {
    echo $'Configuring Avahi'
    if [ ! -f /usr/bin/pacman ]; then
        sudo apt-get -yq install avahi-utils avahi-dnsconfd
    else
        sudo pacman -S --noconfirm avahi nss-mdns
        sudo sed -i 's|hosts:.*|hosts: files mdns_minimal [NOTFOUND=return] dns myhostname|g' /etc/nsswitch.conf
    fi
}

function verify_ssh_server_key {
    ssh -o VisualHostKey=yes -o FingerprintHash=sha256 ${PROJECT_NAME}.local -p 2222 &
    pid=$!
    sleep 15
    kill ${pid}
}

while [ $# -gt 0 ]
do
    key="$1"

    case $key in
        -h|--help)
            show_help
            ;;
        --essid)
            shift
            WIFI_SSID="$1"
            ;;
        --channel)
            shift
            WIFI_CHANNEL=${1}
            ;;
        -s|--setup)
            shift
            SETUP_CLIENT_APP_NAME=${1}
            ;;
        -v|--verify|--verifykeys)
            verify_ssh_server_key
            exit 0
            ;;
        *)
            # unknown option
            ;;
    esac
    shift
done

echo $'Configuring client'
setup_avahi_client
setup_client_app
refresh_gpg_keys
configure_ssh_client
global_rate_limit
remove_known_hosts_entries
echo $'Configuration complete'
exit 0