99 lines
2.6 KiB
Go
99 lines
2.6 KiB
Go
// Copyright 2018 Google Inc.
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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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// Binary dhcp4 obtains a DHCPv4 lease, persists it to
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// /perm/dhcp4/wire/lease.json and notifies netconfigd.
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package main
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import (
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"encoding/json"
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"flag"
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"fmt"
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"io/ioutil"
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"net"
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"os"
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"os/signal"
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"path/filepath"
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"syscall"
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"time"
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"github.com/rtr7/router7/internal/dhcp4"
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"github.com/rtr7/router7/internal/notify"
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"github.com/rtr7/router7/internal/teelogger"
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)
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var log = teelogger.NewConsole()
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func logic() error {
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const leasePath = "/perm/dhcp4/wire/lease.json"
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if err := os.MkdirAll(filepath.Dir(leasePath), 0755); err != nil {
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return err
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}
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iface, err := net.InterfaceByName("uplink0")
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if err != nil {
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return err
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}
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const ackFn = "/perm/dhcp4/wire/ack"
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ack, err := ioutil.ReadFile(ackFn)
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if err != nil && !os.IsNotExist(err) {
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log.Printf("Loading previous DHCPACK packet from %s: %v", ackFn, err)
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}
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c := dhcp4.Client{
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Interface: iface,
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Ack: ack,
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}
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usr2 := make(chan os.Signal, 1)
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signal.Notify(usr2, syscall.SIGUSR2)
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for c.ObtainOrRenew() {
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if err := c.Err(); err != nil {
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log.Printf("Temporary error: %v", err)
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time.Sleep(1 * time.Second)
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continue
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}
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log.Printf("lease: %+v", c.Config())
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b, err := json.Marshal(c.Config())
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if err != nil {
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return err
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}
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if err := ioutil.WriteFile(leasePath, b, 0644); err != nil {
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return fmt.Errorf("persisting lease to %s: %v", leasePath, err)
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}
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if err := ioutil.WriteFile(ackFn, c.Ack, 0644); err != nil {
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return fmt.Errorf("persisting DHCPACK to %s: %v", ackFn, err)
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}
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if err := notify.Process("/user/netconfigd", syscall.SIGUSR1); err != nil {
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log.Printf("notifying netconfig: %v", err)
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}
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select {
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case <-time.After(time.Until(c.Config().RenewAfter)):
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// fallthrough and renew the DHCP lease
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case <-usr2:
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log.Printf("SIGUSR2 received, sending DHCPRELEASE")
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if err := c.Release(); err != nil {
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return err
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}
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os.Exit(125) // quit supervision by gokrazy
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}
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}
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return c.Err() // permanent error
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}
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func main() {
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// TODO: drop privileges, run as separate uid?
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flag.Parse()
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if err := logic(); err != nil {
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log.Fatal(err)
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}
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}
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