detect_external_ip.sh

#!/bin/sh

# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at https://mozilla.org/MPL/2.0/.
#
# This file incorporates work covered by the following copyright and
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#
#   Copyright 2019 Google LLC
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#   Licensed under the Apache License, Version 2.0 (the "License");
#   you may not use this file except in compliance with the License.
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#        http://www.apache.org/licenses/LICENSE-2.0
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if [ -z "${TURN_EXTERNAL_IP}" ]; then
  export TURN_EXTERNAL_IP="$(dig TXT +short @ns1.google.com o-o.myaddr.l.google.com 2>/dev/null | { read output; if [ -z "$output" ] || echo "$output" | grep -q '^;;'; then exit 1; else echo "$(echo $output | sed 's,\",,g')"; fi } || dig -6 TXT +short @ns1.google.com o-o.myaddr.l.google.com 2>/dev/null | { read output; if [ -z "$output" ] || echo "$output" | grep -q '^;;'; then exit 1; else echo "$(echo $output | sed 's,\",,g')"; fi } || hostname -I 2>/dev/null | awk '{print $1; exit}' || echo '127.0.0.1')"
fi

echo "${TURN_EXTERNAL_IP}"