socat/socks4echo.sh

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2008-01-27 12:00:08 +00:00
#! /bin/bash
# $Id: socks4echo.sh,v 1.4 2006/03/21 18:48:53 gerhard Exp $
# Copyright Gerhard Rieger 2004-2006
# 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
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