randomsanity

#! /bin/bash
### BEGIN INIT INFO
# Provides:          randomsanity
# Required-Start:    $network $named $syslog urandom
# Required-Stop:
# Default-Start:     3 4 5
# Default-Stop:
# Description:       Sanity check /dev/urandom at startup
### END INIT INFO

# Author: Gavin Andresen <gavinandresen@gmail.com>

PATH=/sbin:/usr/sbin:/bin:/usr/bin
DESC="Sanity check /dev/urandom using the randomsanity.org REST service"

# Read configuration variable file if it is present
[ -r /etc/default/randomsanity ] && . /etc/default/randomsanity

# Load the VERBOSE setting and other rcS variables
. /lib/init/vars.sh

# Define LSB log_* functions.
. /lib/lsb/init-functions

if [ -z "${BASEURL+x}" ]  # Default if not set in config file:
then
        BASEURL=https://rest.randomsanity.org/v1/q
fi

checkbytes() {
        log_begin_msg "Sanity checking /dev/urandom..."
        URL="$BASEURL/$1"
        # RESPONSE is an array of response lines from the server
        IFS=$'\n' RESPONSE=( $(wget --quiet --tries=1 --output-document=- --timeout=5 --max-redirect=1 --save-headers "$URL" ) )
        WGET_RESULT=$?
        if [ $WGET_RESULT -ne 0 ]
        then
                log_end_msg $WGET_RESULT
                log_warning_msg "wget $URL failed: (${WGET_RESULT})"
                return $WGET_RESULT
        fi
        
        last=$(( ${#RESPONSE[@]}-1 ))  # Index of last line
        case "${RESPONSE[$last]}" in
            true)
                log_end_msg 0
                ;;
            false)
                log_end_msg 1
                log_failure_msg "random sanity check failure"
                ;;
            *)
                log_end_msg 1
                log_warning_msg "Unexpected result from server: ${RESPONSE[$last]}"
                return 1
                ;;
        esac

        return 0
}

case "$1" in
  start)
        hexbytes=$(head --bytes=64 /dev/urandom | od -v -t x1 -An | tr -d '\n ')
        checkbytes "$hexbytes"
        ;;
  stop)
        ;;
  test)
        # Force a failure by using /dev/zero as the source of 'randomness':
        hexbytes=$(head --bytes=64 /dev/zero | od -v -t x1 -An | tr -d '\n ')
        checkbytes "$hexbytes"
        ;;
  *)
        echo "Usage: $SCRIPTNAME {start|test}" >&2
        exit 3
        ;;
esac

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