#! /usr/bin/env bash # source: socks4echo.sh # Copyright Gerhard Rieger and contributors (see file CHANGES) # Published under the GNU General Public License V.2, see file COPYING # perform primitive simulation of a socks4 server with echo function via stdio. # accepts and answers correct SOCKS4 requests, but then just echoes data. # it is required for test.sh # for TCP, use this script as: # socat tcp-l:1080,reuseaddr,crlf system:"socks4echo.sh" # older bash and ksh do not have -n option to read command; we try dd then #if echo a |read -n 1 null >/dev/null 2>&1; then # HAVE_READ_N=1 #else # and newer bash (4.3) has some other problem with read -n HAVE_READ_N= #fi if type socat >/dev/null 2>&1; then SOCAT=socat else SOCAT=./socat fi case `uname` in HP-UX|OSF1) CAT="$SOCAT -u stdin stdout" ;; *) CAT=cat ;; esac if [ $(echo "x\c") = "x" ]; then E="" elif [ $(echo -e "x\c") = "x" ]; then E="-e" else echo "cannot suppress trailing newline on echo" >&2 exit 1 fi ECHO="echo $E" if [ $($ECHO "\0101") = "A" ]; then SOCKSREPLY_FAILED="\0\0133\0\0\0\0\0\0\c" SOCKSREPLY_OK="\0\0132\0\0\0\0\0\0\c" else SOCKSREPLY_FAILED="\0\133\0\0\0\0\0\0\c" SOCKSREPLY_OK="\0\132\0\0\0\0\0\0\c" fi # read and parse SOCKS4 header if [ "$HAVE_READ_N" ]; then read -r -n 1 vn # bash 2.0.3 does not support -n else vn=$(dd bs=1 count=1 2>/dev/null) fi if [ "$vn" != $($ECHO "\04") ]; then $ECHO "$SOCKSREPLY_FAILED" echo "invalid socks version requested" >&2 exit fi if [ "$HAVE_READ_N" ]; then read -r -n 1 cd else cd=$(dd bs=1 count=1 2>/dev/null) fi if [ "$cd" != $($ECHO "\01") ]; then $ECHO "$SOCKSREPLY_FAILED" echo "invalid socks operation requested" >&2 exit fi if [ "$HAVE_READ_N" ]; then read -r -n 6 a else a=$(dd bs=1 count=6 2>/dev/null) fi if [ "$a" != "$($ECHO "}m bL6")" ]; then $ECHO "$SOCKSREPLY_FAILED" echo "$0: wrong socks address or port requested" >&2 echo "$0: expected $($ECHO "}m bL6"|od -t x1), received $($ECHO "$a"|od -t x1)" >&2 exit fi if [ "$HAVE_READ_N" ]; then read -r -n 7 u else u=$(dd bs=1 count=7 2>/dev/null) fi if [ "$u" != "nobody" ]; then $ECHO "$SOCKSREPLY_FAILED" echo "wrong socks user requested" >&2 exit fi # send ok status $ECHO "$SOCKSREPLY_OK" # perform echo function $CAT