#!/bin/bash

# Compile server manager for systemtap
#
# Copyright (C) 2008, 2009 Red Hat Inc.
#
# This file is part of systemtap, and is free software.  You can
# redistribute it and/or modify it under the terms of the GNU General
# Public License (GPL); either version 2, or (at your option) any
# later version.

# This script publishes its presence on the network and then listens for
# incoming connections. When a connection is detected, the stap-server script
# is run to handle the request.

# Catch ctrl-c and other termination signals
trap 'terminate' SIGTERM SIGINT

#-----------------------------------------------------------------------------
# Helper functions.
#-----------------------------------------------------------------------------
# function: initialization PORT
function initialization {
    # Default settings.
    avahi_type=_stap._tcp

    # What port will we listen on?
    port=$1
    test "X$port" = "X" && port=65000
    while netstat -atn | awk '{print $4}' | cut -f2 -d: | egrep -q "^$port\$";
    do
        # Whoops, the port is busy; try another one.
	echo "$0: Port $port is busy"
        port=$((1024+($port + $RANDOM)%64000))
    done

    # Where is the ssl certificate/key database?
    ssl_db=$2
    if test "X$ssl_db" = "X"; then
	# If no certificate/key database has been specified, then find/create
	# a local one.
	if test $EUID = 0; then
	    ssl_db=`dirname $0`/../etc/systemtap/ssl/server
	else
	    ssl_db=$HOME/.systemtap/ssl/server
	fi
	if ! test -f $ssl_db/stap-server.cert; then
	    stap-gen-server-cert `dirname $ssl_db` || exit 1
	fi
    fi
    nss_pw=$ssl_db/pw
    nss_cert=stap-server
}

# function: advertise_presence
#
# Advertise the availability of the server on the network.
function advertise_presence {
    # Build up a string representing our server's properties.
    # TODO: this needs fleshing out.
    local sysinfo=`uname -rvm`
    local txt="sysinfo=$sysinfo"

    # Call avahi-publish-service to advertise our presence.
    avahi-publish-service "Systemtap Compile Server on `uname -n`" \
	$avahi_type $port "$txt" > /dev/null 2>&1 &

    echo "Systemtap Compile Server on `uname -n` listening on port $port"
}

# function: listen
#
# Listen for and handle requests to the server.
function listen {
    # The stap-server-connect program will listen forever
    # accepting requests.
    stap-server-connect -p $port -n $nss_cert -d $ssl_db -w $nss_pw 2>&1 &
    wait '%stap-server-connect' >/dev/null 2>&1
}

# function: fatal [ MESSAGE ]
#
# Fatal error
# Prints its arguments to stderr and exits
function fatal {
    echo "$@" >&2
    terminate
    exit 1
}

# function: terminate
#
# Terminate gracefully.
function terminate {
    echo "$0: Exiting"

    # Kill the running 'avahi-publish-service' job
    kill -s SIGTERM %avahi-publish-service 2> /dev/null
    wait '%avahi-publish-service' >/dev/null 2>&1

    # Kill any running 'stap-server-connect' job.
    kill -s SIGTERM "%stap-server-connect" 2> /dev/null
    wait "%stap-server-connect"  >/dev/null 2>&1

    exit
}

#-----------------------------------------------------------------------------
# Beginning of main line execution.
#-----------------------------------------------------------------------------
initialization "$@"
advertise_presence
listen