#!/bin/bash
# ======================================================================
#
# NAGIOS CLIENT CHECK :: check requirements
#
# Check if a list requirements regarding processes and network 
# connections do exist 
# ----------------------------------------------------------------------
#
# ah=axel.hahn@unibe.ch
#
# 2023-02-13  v1.0  ah 
# ======================================================================


. "$( dirname $0 )/inc_pluginfunctions"

self_APPNAME=$( basename $0 | tr [:lower:] [:upper:] )
self_APPVERSION=1.0

self=$( basename $0 )

typeset -i VERBOSE=0

OUT=

typeset -i COUNT=0
typeset -i COUNTOK=0
typeset -i COUNTERR=0

PROCESSES=

# ----------------------------------------------------------------------
# functions
# ----------------------------------------------------------------------

# show help
function showHelp(){
cat <<EOF
______________________________________________________________________

$self_APPNAME 
v$self_APPVERSION

(c) Institute for Medical Education - University of Bern
Licence: GNU GPL 3
______________________________________________________________________

Check if a list requirements regarding processes and network 
connections do exist.

The check returns OK if all given requirements match.

SYNTAX:
$(basename $0) [-h] [PARAMETERS]

OPTIONS:

    -h or --help         show this help.
    -v or --verbose      show more data: processes and port numbers from
                         /etc/services; add it as first param

PARAMETERS:

    -c|--connect TYPE TARGET PORT        
                         check if connect to a server to a given port
                         is reachable
                         TYPE    string  one of tcp|udp
                         TARGET  string  target host
                         PORT    int     port number
    -p|--process STRING  check if a process with given regex exists
    -t|--tcp PORT        check if connect on local tcp port is reachable;
                         This is a shortcut for -c tcp localhost [port]

The parameters can be repeated multiple times. Checks will be executed in
the given order.

EXAMPLE

$(basename $0) -p httpd -p mysqld -t 22 -t 80 -t 443 -t 3306
     Check if
     - a process httpd and a process mysqld exist
     - localhost listens to ports 22, 80, 443 and 3306

EOF
}


# helper function: add new line in $OUT
function newline(){
        OUT+="
"
}

# check in process list
# param  string  regex to search for in output of "ps aux"
function chkProcess(){
        local label="$1"
        test -z "$PROCESSES" && PROCESSES=$( ps aux )
        COUNT+=1
        local found=$( echo "$PROCESSES" | grep -v "grep" | grep -v "$self" | grep -E "$label" )
        if [ -z "$found" ]; then
                COUNTERR+=1
                ph.setStatus critical
                OUT+="ERROR  process     $label was not found"
        else
                COUNTOK+=1
                OUT+="OK     process     $label ($( echo """$found""" | wc -l ) x)"
                test $VERBOSE -gt 0 && newline
                test $VERBOSE -gt 0 && OUT+="$( echo """$found""" | sed 's#^#    #g')"
                test $VERBOSE -gt 0 && newline
        fi
        newline
}

# check connection
# param  string  type: one of tcp|udp
# param  string  target: a servername eg. localhost or www.example.com
# param  integer port number to connect
function chkConnection(){
        local type="$1"     # tcp | udp
        local target="$2"   # servername
        local port="$3"     # port number
        
        COUNT+=1
        if ! echo "$type/$target/$port" | grep -E "^(tcp|udp)/[a-z][a-z0-9\.\-]*/[1-9][0-9]*$" >/dev/null 2>&1; then
                COUNTERR+=1
                OUT+="ERROR  syntax error detected - verify params for port check; type=$type (one of tcp|udp) target=$target (servername to connect) port=$port"
        else
                if (>/dev/$type/$target/$port) 2>/dev/null; then
                        COUNTOK+=1
                        OUT+="OK     connection  $type to $target on port $port"
                else
                        COUNTERR+=1
                        ph.setStatus critical
                        OUT+="ERROR  connection  $type to $target on port $port FAILED"
                fi
                test $VERBOSE -gt 0 && newline
                test $VERBOSE -gt 0 && OUT+="$( grep """ $port/$type""" /etc/services | sed 's#^#    #g')"
                test $VERBOSE -gt 0 && newline
        fi
        newline
}

# ----------------------------------------------------------------------
# MAIN
# ----------------------------------------------------------------------

if [ "$#" -eq 0 ]; then
        showHelp;
        exit 1
fi

# parse params
while [[ "$#" -gt 0 ]]; do case $1 in
    -c|--connect)   chkConnection "$2" "$3" "$4"; shift;shift;shift;shift ;; 
    -p|--process)   chkProcess "$2";shift 2;;
    -h|--help)      showHelp; exit 0;;
    -t|--tcp)       chkConnection tcp localhost "$2"; shift;shift ;; 
    -v|--verbose)   VERBOSE=1; shift;;
    *) echo "ERROR: Unknown parameter: $1"; showHelp; exit 1;
esac; done

ph.status "$COUNT Requirement checks - errors: $COUNTERR"
echo
echo "STATUS TYPE        RESULT"
echo "$OUT"
ph.exit

# ----------------------------------------------------------------------