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// Copyright (C) 2016 The Syncthing Authors.
//
// 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/.
package main
import (
"context"
"crypto/rand"
"encoding/binary"
"flag"
"log"
"strings"
"time"
"github.com/syncthing/syncthing/lib/beacon"
"github.com/syncthing/syncthing/lib/discover"
"github.com/syncthing/syncthing/lib/protocol"
_ "go.uber.org/automaxprocs"
)
var (
all = false // print all packets, not just first from each device/source
fake = false // send fake packets to lure out other devices faster
mc = "[ff12::8384]:21027"
bc = 21027
)
var (
// Static prefix that we use when generating fake device IDs, so that we
// can recognize them ourselves. Also makes the device ID start with
// "STPROBE-" which is humanly recognizable.
randomPrefix = []byte{148, 223, 23, 4, 148}
// Our random, fake, device ID that we use when sending announcements.
myID = randomDeviceID()
)
func main() {
flag.BoolVar(&all, "all", all, "Print all received announcements (not only first)")
flag.BoolVar(&fake, "fake", fake, "Send fake announcements")
flag.StringVar(&mc, "mc", mc, "IPv6 multicast address")
flag.IntVar(&bc, "bc", bc, "IPv4 broadcast port number")
flag.Parse()
if fake {
log.Println("My ID:", myID)
}
ctx := context.Background()
runbeacon(ctx, beacon.NewMulticast(mc), fake)
runbeacon(ctx, beacon.NewBroadcast(bc), fake)
select {}
}
func runbeacon(ctx context.Context, bc beacon.Interface, fake bool) {
go bc.Serve(ctx)
go recv(bc)
if fake {
go send(bc)
}
}
// receives and prints discovery announcements
func recv(bc beacon.Interface) {
seen := make(map[string]bool)
for {
data, src := bc.Recv()
if m := binary.BigEndian.Uint32(data); m != discover.Magic {
log.Printf("Incorrect magic %x in announcement from %v", m, src)
continue
}
var ann discover.Announce
ann.Unmarshal(data[4:])
if ann.ID == myID {
// This is one of our own fake packets, don't print it.
continue
}
// Print announcement details for the first packet from a given
// device ID and source address, or if -all was given.
key := ann.ID.String() + src.String()
if all || !seen[key] {
log.Printf("Announcement from %v\n", src)
log.Printf(" %v at %s\n", ann.ID, strings.Join(ann.Addresses, ", "))
seen[key] = true
}
}
}
// sends fake discovery announcements once every second
func send(bc beacon.Interface) {
ann := discover.Announce{
ID: myID,
Addresses: []string{"tcp://fake.example.com:12345"},
}
bs, _ := ann.Marshal()
for {
bc.Send(bs)
time.Sleep(time.Second)
}
}
// returns a random but recognizable device ID
func randomDeviceID() protocol.DeviceID {
var id protocol.DeviceID
copy(id[:], randomPrefix)
rand.Read(id[len(randomPrefix):])
return id
}
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