#!/bin/sh # This script is an example captcha script. # It takes the text to recognize in the captcha image as a parameter. # It return the image binary as a result. ejabberd support PNG, JPEG and GIF. # The whole idea of the captcha script is to let server admins adapt it to # their own needs. The goal is to be able to make the captcha generation as # unique as possible, to make the captcha challenge difficult to bypass by # a bot. # Server admins are thus supposed to write and use their own captcha generators. # This script relies on ImageMagick. # It is NOT compliant with ImageMagick forks like GraphicsMagick. INPUT=$1 if test -n ${BASH_VERSION:-''} ; then get_random () { R=$RANDOM } else for n in `od -A n -t u2 -N 48 /dev/urandom`; do RL="$RL$n "; done get_random () { R=${RL%% *} RL=${RL#* } } fi get_random WAVE1_AMPLITUDE=$((2 + $R % 5)) get_random WAVE1_LENGTH=$((50 + $R % 25)) get_random WAVE2_AMPLITUDE=$((2 + $R % 5)) get_random WAVE2_LENGTH=$((50 + $R % 25)) get_random WAVE3_AMPLITUDE=$((2 + $R % 5)) get_random WAVE3_LENGTH=$((50 + $R % 25)) get_random W1_LINE_START_Y=$((10 + $R % 40)) get_random W1_LINE_STOP_Y=$((10 + $R % 40)) get_random W2_LINE_START_Y=$((10 + $R % 40)) get_random W2_LINE_STOP_Y=$((10 + $R % 40)) get_random W3_LINE_START_Y=$((10 + $R % 40)) get_random W3_LINE_STOP_Y=$((10 + $R % 40)) get_random B1_LINE_START_Y=$(($R % 40)) get_random B1_LINE_STOP_Y=$(($R % 40)) get_random B2_LINE_START_Y=$(($R % 40)) get_random B2_LINE_STOP_Y=$(($R % 40)) #B3_LINE_START_Y=$(($R % 40)) #B3_LINE_STOP_Y=$(($R % 40)) get_random B1_LINE_START_X=$(($R % 20)) get_random B1_LINE_STOP_X=$((100 + $R % 40)) get_random B2_LINE_START_X=$(($R % 20)) get_random B2_LINE_STOP_X=$((100 + $R % 40)) #B3_LINE_START_X=$(($R % 20)) #B3_LINE_STOP_X=$((100 + $R % 40)) get_random ROLL_X=$(($R % 40)) convert -size 180x60 xc:none -pointsize 40 \ \( -clone 0 -fill white \ -stroke black -strokewidth 4 -annotate +0+40 "$INPUT" \ -stroke white -strokewidth 2 -annotate +0+40 "$INPUT" \ -roll +$ROLL_X+0 \ -wave "$WAVE1_AMPLITUDE"x"$WAVE1_LENGTH" \ -roll -$ROLL_X+0 \) \ \( -clone 0 -stroke black \ -strokewidth 1 -draw \ "line $B1_LINE_START_X,$B1_LINE_START_Y $B1_LINE_STOP_X,$B1_LINE_STOP_Y" \ -strokewidth 1 -draw \ "line $B2_LINE_START_X,$B2_LINE_START_Y $B2_LINE_STOP_X,$B2_LINE_STOP_Y" \ -wave "$WAVE2_AMPLITUDE"x"$WAVE2_LENGTH" \) \ \( -clone 0 -stroke white \ -strokewidth 2 -draw "line 0,$W1_LINE_START_Y 140,$W1_LINE_STOP_Y" \ -strokewidth 2 -draw "line 0,$W2_LINE_START_Y 140,$W2_LINE_STOP_Y" \ -strokewidth 2 -draw "line 0,$W3_LINE_START_Y 140,$W3_LINE_STOP_Y" \ -wave "$WAVE3_AMPLITUDE"x"$WAVE3_LENGTH" \) \ -distort Perspective '0,0,0,0 0,80,0,80 80,0,80,15 80,80,80,55' \ -flatten -crop 140x60 +repage -quality 90 -depth 8 png:-