132 lines
3.0 KiB
Bash
Executable File
132 lines
3.0 KiB
Bash
Executable File
#!/bin/bash
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# Copyright © 2021 Adrien Bourmault (neox@os-k.eu)
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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# This script is an example captcha script.
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# It takes the text to recognize in the captcha image as a parameter.
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# It return the image binary as a result. ejabberd support PNG, JPEG and GIF.
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# The whole idea of the captcha script is to let server admins adapt it to
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# their own needs. The goal is to be able to make the captcha generation as
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# unique as possible, to make the captcha challenge difficult to bypass by
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# a bot.
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# Server admins are thus supposed to write and use their own captcha generators.
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# This script relies on ImageMagick.
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# It is NOT compliant with ImageMagick forks like GraphicsMagick.
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INPUT=$1
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TRANSFORMATIONS=(INTRUDER SUM)
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DIGIT=(zero one two three four five six seven eight nine ten)
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if test -n "${BASH_VERSION:-''}" ; then
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get_random ()
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{
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R=$RANDOM
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}
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else
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for n in $(od -A n -t u2 -N 64 /dev/urandom); do RL="$RL$n "; done
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get_random ()
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{
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R=${RL%% *}
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RL=${RL#* }
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}
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fi
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INTRUDER()
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{
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NUMBERS=$(echo "$INPUT" | grep -o . | tr '\n' ' ')
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SORTED_UNIQ_NUM=$(echo "${NUMBERS[@]}" | sort -u | tr '\n' ' ')
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RANDOM_DIGITS=$(echo 123456789 | grep -o . | sort -R | tr '\n' ' ')
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INTRUDER=-1
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for i in $RANDOM_DIGITS
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do
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if [[ ! " ${SORTED_UNIQ_NUM[@]} " =~ ${i} ]]; then
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INTRUDER=$i
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break
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fi
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done
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# Worst case
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if [[ $INTRUDER -eq "-1" ]]
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then
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printf "Type %s \n without changes" "$INPUT"
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return
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fi
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for num in ${NUMBERS}
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do
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get_random
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R=$((R % 100))
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if [[ $R -lt 60 ]]; then
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NEWINPUT=${NEWINPUT}${num}${INTRUDER}
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else
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NEWINPUT=${NEWINPUT}${num}
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fi
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done
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get_random
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R=$((R % 100))
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if [[ $R -lt 50 ]]; then
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printf "Type %s by\n deleting the %s" "$NEWINPUT" "${DIGIT[$INTRUDER]}"
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else
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printf "Enter %s by\n removing the %s" "$NEWINPUT" "${DIGIT[$INTRUDER]}"
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fi
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}
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SUM()
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{
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get_random
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RA=$((R % 100))
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if [[ $((INPUT % 2)) -eq 0 ]]; then
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A=$((INPUT - RA))
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B=$RA
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else
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B=$((INPUT - RA))
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A=$RA
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fi
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get_random
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R=$((R % 100))
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if [[ $R -lt 25 ]]; then
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printf "Type the result\n of %s + %s" "$A" "$B"
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elif [[ $R -lt 50 ]]; then
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printf "SUMx\n %s and %s" "$A" "$B"
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elif [[ $R -lt 75 ]]; then
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printf "Add\n %s and %s" "$A" "$B"
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else
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printf "Enter the result\n of %s + %s" "$A" "$B"
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fi
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}
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get_random
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RAND_ITALIC=$((R % 25))
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get_random
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RAND_ANGLE=$((R % 3))
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get_random
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RAND_INDEX=$((R % ${#TRANSFORMATIONS[@]}))
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convert -size 300x60 xc:none -pointsize 20 \
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\( -clone 0 -fill black \
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-stroke black -strokewidth 1 \
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-annotate "${RAND_ANGLE}x${RAND_ITALIC}+0+0" "\n $(${TRANSFORMATIONS[$RAND_INDEX]})" \
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-roll +"$ROLL_X"+0 \
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-wave "$WAVE1_AMPLITUDE"x"$WAVE1_LENGTH" \
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-roll -"$ROLL_X"+0 \) \
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-flatten -crop 300x60 +repage -quality 500 -depth 11 png:-
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