client-functions

###########################################################################
# Implements the client side of the epoptes communications protocol.
# The daemon reads this file when it starts, and sends it to clients when they
# connect. The clients actually source it and then wait for further commands.
#
# Copyright (C) 2010, 2012 Alkis Georgopoulos <alkisg@gmail.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/>.
#
# On Debian GNU/Linux systems, the complete text of the GNU General
# Public License can be found in `/usr/share/common-licenses/GPL'.
###########################################################################

# Output a message and exit with an error.
# Parameters:
# $1..$N = The message.
die() {
    echo "epoptes-client ERROR: $@" >&2
    exit 1
}

# Calculate, export and return a collection of useful variables.
info() {
    local def_iface

    if [ -z cached_info ]; then
        # TODO: use `ip route get server-ip` instead
        def_iface=$(ip -oneline -family inet route show \
            | sed -n '/^default .* dev \([^ ]*\).*/s//\1/p')
        test -z "$def_iface" && die "Empty def_iface"

        test -n "$USER" || USER=$(whoami)
        test -n "$HOME" || HOME=$(getent passwd "$UID" | cut -d: -f6)
        HOSTNAME=$(hostname)
        test -n "$HOSTNAME" || die "Empty hostname"
        IP=$(ip -oneline -family inet addr show dev "$def_iface" | sed "s/.* \([0-9.]*\)\/.*/\\1/")
        test -n "$IP" || die "Empty IP"
        MAC=$(ip -oneline -family inet link show dev "$def_iface" | sed "s/.*ether \([^ ]*\).*/\\1/")
        MAC=$(echo "$MAC" | sed 'y/abcdef-/ABCDEF:/;s/[^A-F0-9:]//g')
        test -n "$MAC" || die "Empty MAC"
        CPU=$(cat /proc/cpuinfo | grep "^model name" | head -1 | sed "s/.*: //")
        RAM=$(free -m | grep "^Mem" | awk '{print $2}')
        VGA=$(lspci -nn -m | sed -n -e '/"VGA/s/[^"]* "[^"]*" "[^"]*" "\([^"]*\)" .*/\1/p')
        OS=$(uname -o)

        # If epoptes-client is ran on a thin client from a user account (meaning
        # that it actually runs on the server), then use $LTSP_CLIENT_HOSTNAME,
        # $LTSP_CLIENT and $LTSP_CLIENT_MAC instead of $HOSTNAME, $IP and $MAC.
        # CPU, RAM and VGA are not available in the environment, so we're leaving
        # the ones of the server.
        if [ "$TYPE" = "thin" ] && [ "$UID" -ne 0 ]; then
            test -n "$LTSP_CLIENT" && IP="$LTSP_CLIENT"
            test -n "$LTSP_CLIENT_HOSTNAME" && HOSTNAME="$LTSP_CLIENT_HOSTNAME"
            test -n "$LTSP_CLIENT_MAC" && MAC="$LTSP_CLIENT_MAC"
        fi

        export HOSTNAME IP MAC TYPE USER UID CPU RAM VGA SERVER PORT
        cached_info=true
    fi
    cat <<EOF
home=$HOME
hostname=$HOSTNAME
ip=$IP
mac=$MAC
os=$OS
type=$TYPE
uid=$UID
user=$USER
version=$VERSION
EOF
}

# Execute a command in the background and print its pid.
# Parameters:
# $1..$N = The command and its parameters.
execute() {
    if [ $# -eq 1 ]; then
        # If there's only one parameter, it might be a file or URL.
        which -- "$1" >/dev/null || set "xdg-open" "$1"
    fi

    # Do some logging, either in ~/.xsession-errors or on the console.
    echo "$(LANG=C date '+%c'), epoptes-client executing: $@" >&2

    # The command is ran with stdin and stdout redirected to /dev/null,
    # so that it doesn't interfere with the output of other commands.
    # stderr isn't changed, i.e. ~/.xsession-errors will be used.
    "$@" 0</dev/null >/dev/null &

    # Print the pid.
    echo $!
}

# Log out the connected user.
logout() {
    ./endsession --logout
}

# Reboot the client.
reboot() {
    ./endsession --reboot
}

# Shut down the client.
shutdown() {
    ./endsession --shutdown
}

# Create a thumbnail of the user screen.
# Parameters:
# $1 = thumbnail width.
# $2 = thumbnail height.
screenshot() {
    if ./screenshot %i %i; then
        BAD_SCREENSHOTS=0
    elif [ "$BAD_SCREENSHOTS" -eq 3 ]; then
        die "3 failed screenshots, exiting..."
    else
        BAD_SCREENSHOTS=$(($BAD_SCREENSHOTS+1))
    fi
}

# Lock the screen.
# Parameters:
# $1 = seconds to keep screen locked, 0 means forever - currently ignored.
# $2 = message to display to the user.
lock_screen() {
    test -n "$EPOPTES_LOCK_SCREEN_PID" && kill "$EPOPTES_LOCK_SCREEN_PID"
    EPOPTES_LOCK_SCREEN_PID=$(execute ./lock-screen "$2")
}

# Unlock a locked screen.
unlock_screen() {
    if [ -n "$EPOPTES_LOCK_SCREEN_PID" ]; then
        kill "$EPOPTES_LOCK_SCREEN_PID"
        unset EPOPTES_LOCK_SCREEN_PID
    fi
}

# Mute the system sound.
# Parameters:
# $1 = seconds to keep sound muted, 0 means forever - currently ignored.
mute_sound() {
    execute amixer -c 0 -q sset Master mute
}

# Unute the system sound.
unmute_sound() {
    execute amixer -c 0 -q sset Master unmute
}

# Display some text to the user.
# Parameters:
# $1 = text.
# $2 = dialog type, one of "info", "warning" or "error".
message() {
    local type

    type=${2:-info}
    if [ -x /usr/bin/zenity ]; then
        execute zenity "--$type" --text "$1"
    elif [ -x /usr/bin/xmessage ]; then
        execute xmessage -center "$1"
    else
        echo "$type: $1" >&2
    fi
}

# Connect to the server to be monitored.
get_monitored() {
    execute x11vnc -noshm -24to32 -viewonly -connect_or_exit "$SERVER"
}

# Connect to the server to get assistance.
get_assisted() {
    execute x11vnc -noshm -24to32 -connect_or_exit "$SERVER"
}

# Deactivate the screensaver, in order for the users to watch a broadcast.
stop_screensaver() {
    if [ -x /usr/bin/gnome-screensaver-command ]; then
        gnome-screensaver-command -d
    fi
}

# Receive a broadcasted screen from the server.
# Parameters:
# $1 = port.
# $2 = fullscreen.
receive_broadcast() {
    stop_transmissions
    export $(./get-display)
    xset dpms force on
    EPOPTES_VNCVIEWER_PID=$(execute sh -c "
sleep 0.$(($(hexdump -e \"%d\" -n 2 /dev/urandom) % 50 + 50)) 
exec xvnc4viewer -Shared -ViewOnly ${2+-FullScreen -UseLocalCursor=0 -MenuKey F13} $SERVER:$1")
}

# The vnc clients should automatically exit when the server is killed.
# Unfortunately, that isn't always true, so try to kill them anyway.
stop_transmissions() {
    test -n "$EPOPTES_VNCVIEWER_PID" && kill "$EPOPTES_VNCVIEWER_PID"
    unset EPOPTES_VNCVIEWER_PID
}

# Open a root terminal inside the X session.
root_term() {
    export $(./get-display)
    execute xterm -e bash -l
}

# Sends a screen session to the server using socat.
# Parameters:
# $1 = port.
remote_term() {
    local screen_params

    if [ "$UID" -eq 0 ]; then
        screen_params="bash -l"
    else
        screen_params="-l"
    fi
    execute sh -c "
cd
sleep 1
TERM=xterm exec socat EXEC:'screen $screen_params',pty,stderr tcp:$SERVER:$1"
}

# Main

# Source the lsb init functions, for log_begin_msg / log_end_msg.
# Unfortunately it seems that Centos and Fedora don't have that file.
if [ -f /lib/lsb/init-functions ]; then
    . /lib/lsb/init-functions
else
    alias log_begin_msg=echo
    alias log_warning_msg=echo
    alias log_end_msg=echo
fi
log_end_msg 0 >&5