mirror of https://github.com/OpenVidu/openvidu.git
106 lines
2.7 KiB
Bash
106 lines
2.7 KiB
Bash
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#!/usr/bin/env sh
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# shellcheck shell=dash
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#/ Use the routing table to find the default internal IP for outgoing packets.
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#/
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#/ This script is useful when running from a machine that sits behind a NAT.
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#/ Due to how NAT works, machines behind it belong to an internal or private
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#/ subnet, with a different address space than the external or public side.
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#/
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#/ Any given machine might have multiple network interfaces, but the most
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#/ common scenario is that only one is actually used for communications with the
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#/ outside world, handling traffic that comes from the external NAT side.
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#/
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#/ This script queries the system's IP routing tables for a dummy external IP,
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#/ which has the effect of providing us with the IP of the network interface
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#/ that would have been used for communicating with that address.
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#/
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#/ Arguments
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#/ ---------
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#/
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#/ --default
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#/
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#/ Find the internal IP address of the default IP route gateway.
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#/ Optional. Default: Enabled.
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#/
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#/ --name <InterfaceName>
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#/
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#/ Find the internal IP address of the specified IP route gateway.
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#/ Optional. Default: Disabled.
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# Shell setup
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# ===========
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# Shell options for strict error checking.
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for OPTION in errexit errtrace pipefail nounset; do
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set -o | grep -wq "$OPTION" && set -o "$OPTION"
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done
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# Trace all commands (to stderr).
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#set -o xtrace
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# Parse arguments
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# ===============
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CFG_DEFAULT="true"
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CFG_NAME=""
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while [ $# -gt 0 ]; do
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case "${1-}" in
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--default)
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CFG_DEFAULT="true"
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;;
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--name)
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if [ -n "${2-}" ]; then
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CFG_NAME="$2"
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shift
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else
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echo "[$0] ERROR: --name expects <InterfaceName>" >&2
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exit 1
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fi
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;;
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*)
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echo "[$0] Invalid argument: '${1-}'" >&2
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exit 1
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;;
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esac
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shift
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done
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# Ensure coherent settings...
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if [ -n "$CFG_NAME" ]; then
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CFG_DEFAULT="false"
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fi
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# Discover internal IP address
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# ============================
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if [ "$CFG_DEFAULT" = "true" ]; then
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# Get main local IP address from the default external route (Internet gateway).
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# Uses "1.0.0.0" as the target address, but any other external IP would work.
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COMMAND='ip -4 -oneline route get 1.0.0.0 | grep -Po "src \K(\d\.?)+"'
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else
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COMMAND="ip -4 -oneline address show dev '$CFG_NAME' | grep -Po 'inet \K(\d\.?)+'"
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fi
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is_valid_ip() {
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# Check if the input looks like an IPv4 address.
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# Doesn't check if the actual values are valid; assumes they are.
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echo "$1" | grep -Eq '^([0-9]{1,3}\.){3}[0-9]{1,3}$'
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}
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if IP="$(eval "$COMMAND")" && is_valid_ip "$IP"; then
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printf '%s' "$IP"
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exit 0
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fi
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echo "[$0] Discovery failed" >&2
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exit 1
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