Golang doesn't send UDP packet to multicast group - go

Question

currently I try to reimplement a C application in go. Part of the C application is to send a string to a multicast group. This produces the following packet captured via tcpdump:
00000000 d4 c3 b2 a1 02 00 04 00 00 00 00 00 00 00 00 00 |................|
00000010 ff ff 00 00 01 00 00 00 14 81 06 56 47 2c 01 00 |...........VG,..|
00000020 46 00 00 00 46 00 00 00 33 33 00 02 10 01 04 ce |F...F...33......|
00000030 ef ca fe 1a 86 dd 60 00 00 00 00 10 11 01 fe 80 |......`.........|
00000040 00 00 00 00 00 00 06 ce ef ff fe ca fe 1a ff 02 |................|
00000050 00 00 00 00 00 00 00 00 00 00 00 02 10 01 be 8f |................|
00000060 03 e9 00 10 99 68 6e 6f 64 65 69 6e 66 6f |.....hnodeinfo|
I tried to replicate the behavior with the following code:
const MultiCastGroup string = "ff02:0:0:0:0:0:2:1001"
const Port int = 1001
const Proto string = "udp6"
const MaxDataGramSize int = 8192
var announcedAddr = &net.UDPAddr{IP: net.ParseIP(MultiCastGroup), Port: Port}
buf := []byte("nodeinfo")
unicastConn, _ := net.ListenUDP(Proto, &net.UDPAddr{IP: net.IPv6zero, Port: 0})
unicastConn.WriteToUDP(buf, announcedAddr)
But the I don't think that it is working, because all I can capture from this via tcpdump is:
00000000 d4 c3 b2 a1 02 00 04 00 00 00 00 00 00 00 00 00 |................|
00000010 ff ff 00 00 01 00 00 00 |........|
00000018
It doesn't seem that the packet is even send. I tried this on a Debian Wheezy machine. Did anyone if you encounter a similar problem with golang and UDP?
Thanks in advance

Answer 1

Did you try to listen for it on another host?
Go (at least in 1.4) had a hard coded disable of loopback on multicast. Which means that, you can't see your own packets.
You can override this by calling setsockopt on the socket FD itself, or:
The golang.org/x/net/ipv6 library can do this for you.
Or you can take the code from Here (have to poke around to find it)