mirror of
https://github.com/fatedier/frp.git
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80 lines
2.1 KiB
Go
80 lines
2.1 KiB
Go
// Copyright 2025 The frp Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package vnet
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import (
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"fmt"
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"io"
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"net"
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"os/exec"
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)
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const (
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defaultTunName = "utun"
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defaultMTU = 1420
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)
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func createTun(addr string) (io.ReadWriteCloser, string, net.IP, error) {
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ifce, name, err := createTunDevice(defaultTunName, defaultMTU)
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if err != nil {
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return nil, "", nil, err
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}
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ip, ipNet, err := net.ParseCIDR(addr)
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if err != nil {
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return nil, "", nil, err
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}
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// Calculate a peer IP for the point-to-point tunnel
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peerIP := generatePeerIP(ip)
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// Configure the interface with proper point-to-point addressing
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if err = exec.Command("ifconfig", name, "inet", ip.String(), peerIP.String(), "mtu", fmt.Sprint(defaultMTU), "up").Run(); err != nil {
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return nil, "", nil, err
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}
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// Add default route for the tunnel subnet
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routes := []net.IPNet{*ipNet}
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if err = addRoutes(name, routes); err != nil {
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return nil, "", nil, err
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}
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return ifce, name, ip, nil
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}
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// generatePeerIP creates a peer IP for the point-to-point tunnel
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// by incrementing the last octet of the IP
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func generatePeerIP(ip net.IP) net.IP {
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// Make a copy to avoid modifying the original
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peerIP := make(net.IP, len(ip))
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copy(peerIP, ip)
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// Increment the last octet
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peerIP[len(peerIP)-1]++
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return peerIP
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}
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// addRoutes configures system routes for the TUN interface
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func addRoutes(ifName string, routes []net.IPNet) error {
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for _, route := range routes {
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routeStr := route.String()
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if err := exec.Command("route", "add", "-net", routeStr, "-interface", ifName).Run(); err != nil {
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return err
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}
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}
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return nil
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}
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