Hi. This is more of a question than an issue:

Will this work on a bridge between two different network interfaces? I'm not using vlans, just looking for a way to have a one-way bonjour reflector (e.g. devices on wlan0 showing up on eth0 but not the other way around).

Thanks :)

I'm wondering if it would be possible to amend this software to facilitate MAC address restrictions on clients as well. Such a config file could look like this:

net_interface = "wls1" # Put here the network interface you want to use.

[devices]

    [devices."AA:BB:CC:DD:EE:FF"]    # A shared bonjour device
    description = "Test Chromecast"
    origin_pool = 1078               # Tag of the VLAN the device is in
    shared_pools = [1234, 3597]      # Tags of the VLANs which can use this device
    shared_devices = ["AA:BB:CC:DD:EE:FA","AA:BB:CC:DD:EE:FB"]   # Mac addresses of devices that can use this device

So in this example, device AA:BB:CC:DD:EE:FB (VLAN 1234) would be able to access AA:BB:CC:DD:EE:FF, but AA:BB:CC:DD:EE:FC (VLAN 1234) would not.

I'm not fluent in Go, so I'm asking if this seems feasible before I dive into it.

I get these errors when trying to run 'go build':

~/go/src/bonjour-reflector $ go build
bonjour-reflector/vendor/github.com/google/gopacket/pcap
vendor/github.com/google/gopacket/pcap/pcap.go:202:7: identifier "_Ctype_struct_bpf_program" may conflict with identifiers generated by cgo
vendor/github.com/google/gopacket/pcap/pcap.go:482:13: identifier "_Ctype_struct_pcap_stat" may conflict with identifiers generated by cgo
vendor/github.com/google/gopacket/pcap/pcap.go:527:49: identifier "_Ctype_struct_bpf_program" may conflict with identifiers generated by cgo
vendor/github.com/google/gopacket/pcap/pcap.go:550:10: identifier "_Ctype_struct_bpf_program" may conflict with identifiers generated by cgo
vendor/github.com/google/gopacket/pcap/pcap.go:583:41: identifier "_Ctype_struct_bpf_insn" may conflict with identifiers generated by cgo
vendor/github.com/google/gopacket/pcap/pcap.go:655:66: identifier "_Ctype_struct_bpf_program" may conflict with identifiers generated by cgo
vendor/github.com/google/gopacket/pcap/pcap.go:668:19: identifier "_Ctype_struct_bpf_insn" may conflict with identifiers generated by cgo
vendor/github.com/google/gopacket/pcap/pcap.go:795:34: identifier "_Ctype_struct_pcap_addr" may conflict with identifiers generated by cgo
vendor/github.com/google/gopacket/pcap/pcap.go:798:56: identifier "_Ctype_struct_pcap_addr" may conflict with identifiers generated by cgo

This may be due to my being a newcomer to GO, so in case this rules in/out user error:
1.) Installed and configured vlans & network switch & router firewall rules using this tutorial:
https://www.sbprojects.net/projects/raspberrypi/vlan.php
Verified desired vlan connections by:
hostname -I

2.) Installed GO Raspberry Pi 3B running Stretch:
$mkdir -p $HOME/go/src $HOME/go/bin
$ InstallFile='go1.12.9.linux-armv6l.tar.gz'
$ wget https://dl.google.com/go/$InstallFile
$ sudo tar -C /usr/local -xvf $InstallFile
$ echo 'export GOPATH=$HOME/go' >> ~/.profile
$ echo 'export PATH=/usr/local/go/bin:$PATH:$GOPATH/bin' >> ~/.profile
$ source ~/.profile

3.) Create, build & run, and install & run test GO program:
$ mkdir ~/go/src/hellotest && vi ~/go/src/hellotest/hello.go
hello.go contents:
package main
`import "fmt"`
func main() {
fmt.Printf("hello, world, Version 2\n")
}
Build and run:
$ cd ~/go/src/hellotest
$ go build
$ ./hellotest
hello, world Version 2
Install and run:
$ cd ~/go/src/hellotest
$ go install
$ cd ~
$ hellotest
hello, world Version 2

4.) Install git & dep & libpcap-dev
$ sudo apt-get update && sudo apt-get install git -y
$ wget https://raw.githubusercontent.com/golang/dep/master/install.sh
$ chmod 755 install.sh
$ ./install.sh
# (no error msgs)
$ ln -s $HOME/go/bin/dep /usr/bin/
$ \ls -1 ~/go/bin
dep
hellov2
$ sudo apt-get install libpcap-dev -y
$ cd ~/go/src
$ git clone https://github.com/Gandem/bonjour-reflector.git
$ cd ~/go/src/bonjour-reflector
# CONFIGURED config.toml
$ vi config.toml
$ dep ensure
# (no error msgs)
$ go build

Then got the error messages at beginning of this issue/post and no generated file called ~/go/src/bonjour-reflector/bonjour-reflector

I've just set up this reflector and configured it to reflect my Google Home Mini located in VLAN200 to VLANS 100, 300 and 400. The query packets from these VLANs are successfully reflected to VLAN200, however there's no response from Google Home Mini (I'm using MikroTik's sniffer to check the VLAN200 packets). When a device sends an mDNS query on the same VLAN, the Home Mini responds correctly. I've disabled all firewall rules as to not interfere, but I did not help.

I can provide a pcap file if that would help resolve my issue, thanks in advance.

EDIT: Seems like the issue is that this reflector does not replace the source IP of the packets when reflecting them and the devices do not respond since it's not the same network

As I'm completely new to Go and no programmer, I am wondering howto get started ?
I would use a standard Ubuntu VM.

OS: 20.04.3 LTS
GO version: 1.19.3 arm64
Platform Raspberry Pi4

Compiled bonjour-reflector and built a simple config to allow access to a chrome-cast from another vlan:

netplan config (not sure it matters):

network:
        version: 2
        ethernets:
                eth0:
                        dhcp4: false
        vlans:
                vlan1000:
                        id: 1000
                        addresses: [10.16.191.14/24]
                        gateway4: 10.16.191.1
                        nameservers:
                                addresses: [8.8.8.8,8.8.4.4]
                        link: eth0

config.toml:

net_interface = "eth0"
[devices]
        [devices."A4:77:33:89:20:E6"]
        description = "Chromecast in Lab"
        origin_pool = 702
        shared_pools = [701]

excuting: ./bonjour-reflector -config=./config.toml

Output snippet.

PACKET: 86 bytes, wire length 86 cap length 86 @ 2022-11-03 10:30:45.739136 +0000 UTC
- Layer 1 (14 bytes) = Ethernet {Contents=[..14..] Payload=[..72..] SrcMAC=a4:77:33:89:20:e6 DstMAC=01:00:5e:00:00:fb EthernetType=Dot1Q Length=0}
- Layer 2 (04 bytes) = Dot1Q    {Contents=[2, 190, 8, 0] Payload=[..68..] Priority=0 DropEligible=false VLANIdentifier=702 Type=IPv4}
- Layer 3 (20 bytes) = IPv4     {Contents=[..20..] Payload=[..48..] Version=4 IHL=5 TOS=0 Length=68 Id=0 Flags=DF FragOffset=0 TTL=255 Protocol=UDP Checksum=35723 SrcIP=10.16.5.18 DstIP=224.0.0.251 Options=[] Padding=[]}
- Layer 4 (08 bytes) = UDP      {Contents=[..8..] Payload=[..40..] SrcPort=5353(mdns) DstPort=5353(mdns) Length=48 Checksum=39814}
- Layer 5 (40 bytes) = Payload  40 byte(s)

PACKET: 398 bytes, wire length 398 cap length 398 @ 2022-11-03 10:30:45.739454 +0000 UTC
- Layer 1 (14 bytes) = Ethernet {Contents=[..14..] Payload=[..384..] SrcMAC=a4:77:33:89:20:e6 DstMAC=01:00:5e:00:00:fb EthernetType=Dot1Q Length=0}
- Layer 2 (04 bytes) = Dot1Q    {Contents=[2, 190, 8, 0] Payload=[..380..] Priority=0 DropEligible=false VLANIdentifier=702 Type=IPv4}
- Layer 3 (20 bytes) = IPv4     {Contents=[..20..] Payload=[..360..] Version=4 IHL=5 TOS=0 Length=380 Id=0 Flags=DF FragOffset=0 TTL=255 Protocol=UDP Checksum=35411 SrcIP=10.16.5.18 DstIP=224.0.0.251 Options=[] Padding=[]}
- Layer 4 (08 bytes) = UDP      {Contents=[..8..] Payload=[..352..] SrcPort=5353(mdns) DstPort=5353(mdns) Length=360 Checksum=5335}
- Layer 5 (352 bytes) = Payload 352 byte(s)

PACKET: 107 bytes, wire length 107 cap length 107 @ 2022-11-03 10:30:54.06189 +0000 UTC
- Layer 1 (14 bytes) = Ethernet {Contents=[..14..] Payload=[..93..] SrcMAC=46:63:7e:ea:a5:49 DstMAC=01:00:5e:00:00:fb EthernetType=Dot1Q Length=0}
- Layer 2 (04 bytes) = Dot1Q    {Contents=[2, 189, 8, 0] Payload=[..89..] Priority=0 DropEligible=false VLANIdentifier=701 Type=IPv4}
- Layer 3 (20 bytes) = IPv4     {Contents=[..20..] Payload=[..69..] Version=4 IHL=5 TOS=0 Length=89 Id=41119 Flags= FragOffset=0 TTL=2 Protocol=UDP Checksum=12221 SrcIP=10.16.253.44 DstIP=224.0.0.251 Options=[] Padding=[]}
- Layer 4 (08 bytes) = UDP      {Contents=[..8..] Payload=[..61..] SrcPort=5353(mdns) DstPort=5353(mdns) Length=69 Checksum=51551}
- Layer 5 (61 bytes) = Payload  61 byte(s)

PACKET: 107 bytes, wire length 107 cap length 107 @ 2022-11-03 10:30:55.064249 +0000 UTC
- Layer 1 (14 bytes) = Ethernet {Contents=[..14..] Payload=[..93..] SrcMAC=46:63:7e:ea:a5:49 DstMAC=01:00:5e:00:00:fb EthernetType=Dot1Q Length=0}
- Layer 2 (04 bytes) = Dot1Q    {Contents=[2, 189, 8, 0] Payload=[..89..] Priority=0 DropEligible=false VLANIdentifier=701 Type=IPv4}
- Layer 3 (20 bytes) = IPv4     {Contents=[..20..] Payload=[..69..] Version=4 IHL=5 TOS=0 Length=89 Id=41127 Flags= FragOffset=0 TTL=2 Protocol=UDP Checksum=12213 SrcIP=10.16.253.44 DstIP=224.0.0.251 Options=[] Padding=[]}
- Layer 4 (08 bytes) = UDP      {Contents=[..8..] Payload=[..61..] SrcPort=5353(mdns) DstPort=5353(mdns) Length=69 Checksum=51551}
- Layer 5 (61 bytes) = Payload  61 byte(s)

PACKET: 86 bytes, wire length 86 cap length 86 @ 2022-11-03 10:31:14.24797 +0000 UTC
- Layer 1 (14 bytes) = Ethernet {Contents=[..14..] Payload=[..72..] SrcMAC=a4:77:33:89:20:e6 DstMAC=01:00:5e:00:00:fb EthernetType=Dot1Q Length=0}
- Layer 2 (04 bytes) = Dot1Q    {Contents=[2, 190, 8, 0] Payload=[..68..] Priority=0 DropEligible=false VLANIdentifier=702 Type=IPv4}
- Layer 3 (20 bytes) = IPv4     {Contents=[..20..] Payload=[..48..] Version=4 IHL=5 TOS=0 Length=68 Id=0 Flags=DF FragOffset=0 TTL=255 Protocol=UDP Checksum=35723 SrcIP=10.16.5.18 DstIP=224.0.0.251 Options=[] Padding=[]}
- Layer 4 (08 bytes) = UDP      {Contents=[..8..] Payload=[..40..] SrcPort=5353(mdns) DstPort=5353(mdns) Length=48 Checksum=35207}
- Layer 5 (40 bytes) = Payload  40 byte(s)

A capture on the interface shows mDNS packets are forwarded out the port for the host running bonjour-reflector, but nothing comes back.

I have avahi running fine, i obviously disable it before running bonjour-reflector.

What am i doing wrong and once i get that sorted is there a process for demonizing the process?

I have a use-case that this could be the perfect fit for but I don’t understand enough about networking to know.

On MacOS, setting Docker to use the “host” network is a no-op - docker will simply ignore this and isolate the network anyway.

I’m using a software called Home Assistant, which integrates with Apple’s HomeKit, and there’s a section for this integration specifically dealing with Docker, where usage of avahi-daemon is recommended, in reflector mode (so the HomeKit app can find the HA instance running inside docker). See Docker network isolation here: https://www.home-assistant.io/integrations/homekit

avahi-daemon is unfortunately not available for MacOS, and this library looks like it could provide similar functionality. However, at least for a networking dummy like me, its fine-grained control is a bit intimidating.

For starters I couldn’t get it to run due to some Go installation problems, but even if I did manage to run it, what would I include in the toml file? Do the devices I want to repeat mDNS for have to be defined in both sides? Where would I find their interface? And how do I know the name/ID of the VLAN they’re running on? Mind you, HA isn’t an actual device, it only emulates one.

CPU usage seems to be quite high, I compiled bonjour-reflector on MIPS architecture and I get 100% load (of course it's not a very powerful CPU to start with...). I'm wondering if packet processing could be threaded, source VLANs filtered earlier or something.

Is there any wildcard support when listing devices in the config.toml?

For example:
[devices."*"] = "any device"
[devices."ab:cd:ef:*"] or [devices."ab:cd:ef"] = "any device with a mac that starts with ab:cd:ef

I've tried various approaches, including *, .*, 00:00:00:00:00:00, FF:FF:FF:FF:FF:FF without success.

Not strong in go but I didn't see anything in the code that looked like it handled wildcard values.