mirror of
https://github.com/ethereum/go-ethereum.git
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72 lines
1.8 KiB
Go
72 lines
1.8 KiB
Go
// Copyright 2026 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser 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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// The go-ethereum library 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 Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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//go:build linux
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package nat
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import (
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"bufio"
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"bytes"
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"encoding/binary"
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"net"
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"os"
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"strconv"
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"strings"
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)
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func defaultGatewayIPs() []net.IP {
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data, err := os.ReadFile("/proc/net/route")
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if err != nil {
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return nil
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}
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return parseLinuxRouteTable(data)
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}
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func parseLinuxRouteTable(data []byte) []net.IP {
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var gws []net.IP
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scanner := bufio.NewScanner(bytes.NewReader(data))
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if !scanner.Scan() {
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return nil
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}
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for scanner.Scan() {
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fields := strings.Fields(scanner.Text())
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if len(fields) < 4 || fields[1] != "00000000" {
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continue
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}
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flags, err := strconv.ParseUint(fields[3], 16, 16)
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if err != nil || flags&0x2 == 0 {
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continue
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}
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gw, err := parseLinuxRouteHexIPv4(fields[2])
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if err != nil || gw == nil {
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continue
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}
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gws = append(gws, gw)
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}
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return gws
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}
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func parseLinuxRouteHexIPv4(s string) (net.IP, error) {
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n, err := strconv.ParseUint(s, 16, 32)
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if err != nil {
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return nil, err
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}
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var buf [4]byte
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binary.LittleEndian.PutUint32(buf[:], uint32(n))
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return net.IPv4(buf[0], buf[1], buf[2], buf[3]).To4(), nil
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}
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