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https://repo.or.cz/socat.git
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111 lines
3 KiB
Bash
Executable file
111 lines
3 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 perform group communications, sometimes called brokering.
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# It starts a Socat instance that forks a child process for each
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# connected client; the child processes communicate via IPv4 broadcast
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# Examples:
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# socat-broker.sh TCP-L:1234
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# Now connect with any number of clients like TCP:<server>:1234
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# socat-broker.sh SSL-L:1234,cert=server.pem,cafile=clients.crt
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# Now connect with an arbitrary number of clients like SSL:<server>:1234,cafile=server,cert=clients.pem
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ECHO="echo -e"
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usage () {
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$ECHO "Usage: $0 <options> <listener>"
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$ECHO " <listener> is a passive address like TCP4-L or SSL-L"
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$ECHO " <options>:"
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$ECHO " -d* -S -t <timeout> -T <timeout> are passed to socat"
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$ECHO " -V Shows executed Socat commands and some infos"
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$ECHO "For example:"
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$ECHO " $0 \\"
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$ECHO " TCP4-L:1234"
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$ECHO "Then connect with clients to port 1234"
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$ECHO "Data sent by any client is forwarded to all other clients"
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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 "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="$1"
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if [ -z "$LISTENER" ]; then
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echo "$0: Missing parameter" >&2
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usage >&2
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exit 1
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fi
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shopt -s nocasematch
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if ! [[ "$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 a free UDP port (on loopback)
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if [ -z "$LOWPORT" ]; then
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PORT=$($SOCAT -d -d -T 0.000001 UDP4-RECV:0 /dev/null 2>&1 |grep bound |sed 's/.*:\([1-9][0-9]*\)$/\1/')
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fi
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if [ -z "$PORT" ]; 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 "$0: Failed to determine free UDP port (old Socat version, no ss, no netstat?)" >&2
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exit 1
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fi
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PORT=
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while [ -z "$PORT" ] || ss -aun |grep -e ":$PORT\>" >/dev/null; do
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if [ -z "$LOWPORT" ]; then
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PORT=$((16384+RANDOM))
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else
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PORT=$((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 port $PORT" >&2
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BCADDR=127.255.255.255
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if [ "$VERBOSE" ]; then
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echo -e "$SOCAT -lp socat-broker $OPTS \\
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$LISTENER \
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UDP4-DATAGRAM:$BCADDR:$PORT,bind=:$PORT,so-broadcast,so-reuseaddr"
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fi
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$SOCAT -lp socat-broker $OPTS \
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"$LISTENER" \
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"UDP4-DATAGRAM:$BCADDR:$PORT,bind=:$PORT,so-broadcast,so-reuseaddr"
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