78 lines
1.9 KiB
Go
78 lines
1.9 KiB
Go
/*
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* Copyright (c) 2018 Unrud<unrud@outlook.com>
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*
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* This file is part of Remote-Touchpad.
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*
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* Foobar is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Remote-Touchpad is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Foobar. If not, see <http://www.gnu.org/licenses/>.
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*/
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package main
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import (
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"fmt"
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"net"
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"strings"
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)
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func FindDefaultHost() string {
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fallbackAddr := ""
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for _, publicIP := range []string{"2001:4860:4860::8888", "8.8.8.8"} {
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addr := fmt.Sprintf("[%s]:80", publicIP)
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conn, err := net.Dial("udp", addr)
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if err != nil {
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continue
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}
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conn.Close()
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host, _, err := net.SplitHostPort(conn.LocalAddr().String())
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if err != nil {
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continue
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}
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return host
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}
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interfaces, err := net.Interfaces()
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if err != nil {
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goto fallback
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}
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for _, inter := range interfaces {
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if inter.Flags&net.FlagUp == 0 || inter.Flags&net.FlagLoopback != 0 {
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continue
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}
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addrs, err := inter.Addrs()
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if err != nil {
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continue
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}
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addrs:
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for _, addr := range addrs {
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ip, _, err := net.ParseCIDR(addr.String())
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if err != nil {
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continue
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}
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if fallbackAddr == "" {
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fallbackAddr = ip.String()
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}
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for _, linkLocalPrefix := range []string{"169.254.", "fe8", "fe9", "fea", "feb"} {
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if strings.HasPrefix(ip.String(), linkLocalPrefix) {
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continue addrs
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}
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}
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return ip.String()
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}
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}
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fallback:
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if fallbackAddr != "" {
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return fallbackAddr
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}
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return "localhost"
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}
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