mirror of
https://repo.or.cz/socat.git
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142 lines
4.4 KiB
Bash
Executable file
142 lines
4.4 KiB
Bash
Executable file
#! /usr/bin/env bash
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# Copyright Gerhard Rieger and contributors (see file CHANGES)
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# Published under the GNU General Public License V.2, see file COPYING
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# Shell script to build a many-to-one, one-to-all communication
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# It starts two Socat instances that communicate via IPv4 broadcast,
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# the first of which forks a child process for each connected client.
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# Example:
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# Consider a serial device connected to the Internet on TCP port 1234, it
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# accepts only one connection at a time.
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# On a proxy/relay server run this script:
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# socat-mux.sh \
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# TCP-L:1234,reuseaddr,fork \
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# TCP:<addr-of-device>:1234
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# Now connect with an arbitrary number of clients to TCP:<proxy>:1234;
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# data sent by the device goes to all clients, data from any client is sent to
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# the device.
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ECHO="echo -e"
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usage () {
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$ECHO "Usage: $0 <options> <listener> <target>"
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$ECHO "Example:"
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$ECHO " $0 TCP4-L:1234,reuseaddr,fork TCP:10.2.3.4:12345"
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$ECHO "Clients may connect to port 1234; data sent by any client is forwarded to 10.2.3.4,"
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$ECHO "data provided by 10.2.3.4 is sent to ALL clients"
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$ECHO " <options>:"
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$ECHO "\t-h\tShow this help text and exit"
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$ECHO "\t-V\tShows executed Socat commands and some infos"
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$ECHO "\t-q\tSuppress most messages"
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$ECHO "\t-d*\tOptions beginning with -d are passed to Socat processes"
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$ECHO "\t-l*\tOptions beginning with -l are passed to Socat processes"
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$ECHO "\t-b|-S|-t|-T|-l <arg>\tThese options are passed to Socat processes"
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}
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VERBOSE= QUIET= OPTS=
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while [ "$1" ]; do
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case "X$1" in
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X-h) usage; exit ;;
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X-V) VERBOSE=1 ;;
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X-q) QUIET=1; OPTS="-d0" ;;
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X-d*|X-l?*) OPTS="$OPTS $1" ;;
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X-b|X-S|X-t|X-T|X-l) OPT=$1; shift; OPTS="$OPTS $OPT $1" ;;
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X-) break ;;
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X-*) echo "$0: Unknown option \"$1\"" >&2
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usage >&2
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exit 1 ;;
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*) break ;;
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esac
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shift
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done
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LISTENER="$1"
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TARGET="$2"
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if [ -z "$LISTENER" -o -z "$TARGET" ]; then
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echo "$0: Missing parameter(s)" >&2
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usage >&2
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exit 1
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fi
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shopt -s nocasematch
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if ! [[ "$LISTENER" =~ .*,fork ]] || [[ "$LISTENER" =~ .*,fork, ]]; then
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LISTENER="$LISTENER,fork"
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fi
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case "$0" in
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*/*) if [ -x ${0%/*}/socat ]; then SOCAT=${0%/*}/socat; fi ;;
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esac
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if [ -z "$SOCAT" ]; then SOCAT=socat; fi
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[ "$VERBOSE" ] && echo "# $0: Using executable $SOCAT" >&2
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# When run as root we try low ports
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LOWPORT=
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PATTERN=bound
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if [ "$(id -u)" = 0 ]; then
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LOWPORT="lowport"
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PATTERN="successfully prepared local socket"
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fi
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# We need two free UDP ports (on loopback)
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if [ -z "$LOWPORT" ]; then
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PORT1=$($SOCAT -d -d -T 0.000001 UDP4-RECV:0 /dev/null 2>&1 |grep "$PATTERN" |sed 's/.*:\([1-9][0-9]*\)$/\1/')
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PORT2=$($SOCAT -d -d -T 0.000001 UDP4-RECV:0 /dev/null 2>&1 |grep "$PATTERN" |sed 's/.*:\([1-9][0-9]*\)$/\1/')
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fi
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if [ -z "$PORT1" -o -z "$PORT2" ]; then
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# Probably old Socat version, use a different approach
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if type ss >/dev/null 2>&1; then
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:
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elif type netstat >/dev/null 2>&1; then
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alias ss=netstat
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else
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echo "$0: Failed to determine free UDP ports (old Socat version, no ss, no netstat?)" >&2
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exit 1
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fi
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PORT1= PORT2=
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while [ -z "$PORT1" -o -z "$PORT2" -o "$PORT1" = "$PORT2" ] || ss -aun |grep -e ":$PORT1\>" -e ":$PORT2\>" >/dev/null; do
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if [ -z "$LOWPORT" ]; then
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PORT1=$((16384+RANDOM))
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PORT2=$((16384+RANDOM))
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else
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PORT1=$((512+(RANDOM>>6) ))
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PORT2=$((512+(RANDOM>>6) ))
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fi
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done
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fi
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[ "$VERBOSE" ] && echo "# $0: Using UDP ports $PORT1, $PORT2" >&2
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IFADDR=127.0.0.1
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BCADDR=127.255.255.255
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pid1= pid2=
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trap '[ "$pid1" ] && kill $pid1 2>/dev/null; [ "$pid2" ] && kill $pid2 2>/dev/null' EXIT
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set -bm
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trap 'if kill -n 0 $pid1 2>/dev/null; then [ -z "$QUIET" ] && echo "$0: socat-listener exited with rc=$?" >&2; kill $pid1; else [ -z "$QUIET" ] && echo "$0: socat-multiplexer exited with rc=$?" >&2; kill $pid2 2>/dev/null; fi; exit 1' SIGCHLD
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if [ "$VERBOSE" ]; then
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$ECHO "$SOCAT -lp muxfwd $OPTS \\
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\"$TARGET\" \\
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\"UDP4-DATAGRAM:$BCADDR:$PORT2,bind=$IFADDR:$PORT1,so-broadcast\" &"
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fi
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$SOCAT -lp muxfwd $OPTS \
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"$TARGET" \
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"UDP4-DATAGRAM:$BCADDR:$PORT2,bind=$IFADDR:$PORT1,so-broadcast" &
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pid1=$!
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if [ "$VERBOSE" ]; then
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$ECHO "$SOCAT -lp muxlst $OPTS \\
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\"$LISTENER\" \\
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\"UDP4-DATAGRAM:$IFADDR:$PORT1,bind=:$PORT2,so-broadcast,so-reuseaddr\" &"
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fi
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$SOCAT -lp muxlst $OPTS \
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"$LISTENER" \
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"UDP4-DATAGRAM:$IFADDR:$PORT1,bind=:$PORT2,so-broadcast,so-reuseaddr" &
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pid2=$!
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wait
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#wait -f
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