#!/usr/bin/env bash

# This script allows getting the Techical Add-on for Unix and Linux data into
# Splunk from systems that are not running a Splunk Universal Forwarder.
# This is useful for systems with small or read-only file-systems.
#
# ## Sample rsyslog.conf:
# # Config for handling remote logs
# template(name="RemoteLogs" type="string" string="/share/syslog/%FROMHOST%/%$.myprogramname%/%$.myprogramname%-%$YEAR%-%$MONTH%-%$DAY%.log")
# # Write raw messages for splunk logs
# template(name="RawMessageOnly" type="string" string="%$.mymsg%\n")
# # Look for logs with nix_ta to apply RawMessagesOnly and send to RemoteLogs
# if ($syslogtag startswith 'nix_ta_') then {
#   set $.mymsg = ltrim(rtrim(replace($msg, "#011", " ")));
#   action(type="omfile" dynaFile="RemoteLogs" template="RawMessageOnly"
#     fileCreateMode="0644" dirCreateMode="0755"
#     fileOwner="root" fileGroup="splunk"
#     dirOwner="root" dirGroup="splunk")
#   stop
# }
# # End of sample rsyslog.conf
#
# ## run_nix_ta_commands configuration file
# * Create a new file (/etc/nix_ta.conf) with the following settings in it
#   * ta_home: The directory you copied the Technical Add-on for Unix and Linux files
#   * tag_prefix: The events will be sent to syslog with ${tag_prefix}SCRIPTNAME as a tag
#   * syslog_server: The UDP syslog server to send events to
#   * run_minute: For scripts that have intervals over an hour, which minute to run them
#   * run_hour: For scripts that run once a day, which hour to run them
#   * facility: For logger commands like OpenBSD that do not support pointing to a syslog_server directly
#               Set to something like "local3.info"
#
# ## Using syslog facility instead of specifying a syslog server with logger
# Using $facility when logger does not support specifying $syslog_server:
# Modify local syslog server to send logs for $facility to the $syslog_server
# On OpenBSD, an example for /etc/syslog.conf is:
#   local3.*                             @192.168.1.1
#
# ## Cron job example:
#   * * * * * /path/to/script/run_nix_ta_commands

# Ensure the logger command is available
which logger > /dev/null 2>&1 || { echo "Error: The logger command is required for this script"; exit; }

# Ensure PATH has correct paths
export PATH=$PATH:/usr/local/sbin:/usr/local/bin

# Example/default settings -- override in /etc/nix_ta.conf
ta_home=/srv/TA-unix
tag_prefix=nix_ta_
syslog_server=192.168.1.1
run_minute=2
run_hour=6
facility=

[ -r /etc/nix_ta.conf ] && . /etc/nix_ta.conf

# Get the current minute now to be consistent through the script run
minute=$(printf "%d" $((10#$(date +%M))))
# Get the current hour now to be consistent through the script run
hour=$(printf "%d" $((10#$(date +%H))))
# Set defaults disabling force-mode and list-mode
force=0
list=0

usage() {
  echo "usage: $(basename $0) [-h] [-f] [-l] [script]"
  echo "          -h: print this help text"
  echo "          -f: run all enabled scripts regardless of interval"
  echo "          -l: list scripts, enabled status, and interval (if enabled)"
  exit
}

# Get the command line options
while getopts ":hlf" opt; do
  case $opt in
    f) force=1 ;;
    l) list=1 ;;
    *) usage ;;
  esac
done
shift $((OPTIND -1))

# Function to actually run the script and pipe it to logger
runit() {
  [ -z "$1" ] && return 1
  if [ -x $ta_home/bin/$1.sh ]; then
    if [ -n "$facility" ]; then
      { $ta_home/bin/$1.sh 2> /dev/null; echo; } | logger -p $facility -t ${tag_prefix}$(echo $1|tr '[A-Z]' '[a-z]')
    else
      { $ta_home/bin/$1.sh 2> /dev/null; echo; } | logger -n $syslog_server -t ${tag_prefix}$(echo $1|tr '[A-Z]' '[a-z]')
    fi
  else
    echo Could not find $1 in $ta_home/bin
    return 1
  fi
}

# Check the inputs.conf to see if any of the checks are disabled
declare -A scripts
declare -A intervals
# Load defaults first
if [ -r $ta_home/default/inputs.conf ]; then
  eval $(awk -F '[=#]' '
    /^\[/{name=""}
    /^\[script:\/\//{n=split($1,a,"/");name=gensub(/\.[a-z]+\]/,"",1,a[n]);printf "scripts[%s]=1\nintervals[%s]=60\n",name,name}
    name!="" && $1~/(^|\s*)disabled(\s*|$)/ {disabled=gensub(/(^ | $)/,"","g",gensub(/true/,"1",1,gensub(/false/,"0",1,$2)));printf "scripts[%s]=%s\n",name,disabled}
    name!="" && $1~/(^|\s*)interval(\s*|$)/ {interval=gensub(/(^ | $)/,"","g",$2);printf "intervals[%s]=%s\n",name,interval}
    ' $ta_home/default/inputs.conf)
fi
# See if any defaults are overridden in the local directory
if [ -r $ta_home/local/inputs.conf ]; then
  eval $(awk -F '[=#]' '
    /^\[/{name="";disabled=1;interval=60}
    /^\[script:\/\//{n=split($1,a,"/");name=gensub(/\.[a-z]+\]/,"",1,a[n])}
    name!="" && $1~/(^|\s*)disabled(\s*|$)/ {disabled=gensub(/(^ | $)/,"","g",gensub(/true/,"1",1,gensub(/false/,"0",1,$2)));printf "scripts[%s]=%s\n",name,disabled}
    name!="" && $1~/(^|\s*)interval(\s*|$)/ {interval=gensub(/(^ | $)/,"","g",$2);printf "intervals[%s]=%s\n",name,interval}
    ' $ta_home/local/inputs.conf)
fi

# If -l, just print the scripts
if [ $list = 1 ]; then
  for script in "${!scripts[@]}"; do
    if [ "${scripts[$script]}" = "0" ]; then
      echo "$script is enabled (${intervals[$script]} seconds)"
    else
      echo "$script is disabled"
    fi
  done
  exit
fi

# If a script is specified on the command line, run it (even if disabled)
if [ "$1" ]; then
  runit $1
  exit
fi

# Without -l or -f, loop through the enabled scripts and run them at their interval
for script in "${!scripts[@]}"; do
  # Only run enabled scripts
  if [ "${scripts[$script]}" = "0" ]; then
    i=${intervals[$script]}
    [ $i -lt 60 ] && i=60
    min=$((i/60))

    # If -f, always run each script
    if [ $force = 1 ]; then
      runit $script

    # If interval is 60 seconds or less, run every minute
    elif [ $min -le 1 ]; then
      runit $script

    # If the current minute is divisible by the number of interval minutes, run
    # example: 600 is 5 minutes, it'll run at 0, 5, 10, 15, ... minutes
    elif [ $((minute % min)) = 0 ]; then
      runit $script

    # If interval is an hour or more
    elif [ $min -gt 60 ]; then
      hr=$((i/60/60))

      # If interval is 1 hour or less, run every hour on $run_minute
      if [ $hr -le 1 ] && [ $minute = $run_minute ]; then
        runit $script

      # If the current hour is divisible by the number of interval hours, run
      # example: 21600 is 6 hours, it'll run at 0, 6, 12, 18 hours
      elif [ $((hour % hr)) = 0 ] && [ $minute = $run_minute ]; then
        runit $script

      # If the number of hours is 24 or more, run every day at $run_hour:$run_minute
      elif [ $hr -ge 24 ] && [ $hour = $run_hour ] && [ $minute = $run_minute ]; then
        runit $script
      fi
    fi
  fi
done