Go 1.9 introduced error on UDP Multicast JoinGroup

[Paul Stead]

Hi all,

I upgraded to Go 1.9 and since then UDP multicast code that has been running fine for over a year is now failing on JoinGroup.  I run this program on linux Mint 18 as root (using sudo), both for the multicast permissions and also to allow listening on TCP port 80 and redirecting to port 443 for SSL.  The error returned from JoinGroup is "operation not permitted" which I could expect for a non-privileged user, but not for root.  

If I recompile the program using Go 1.8.3 the exact same works again.

I won't show all the code since there are several structs and "objects" involved, but here's the failing bit, with the interface, listen address, and group address all hard coded just for this example:

iFace := "eno1"

listenAddr := "0.0.0.0:12080"

grpAddress := "224.0.0.12"

inetConn, err3 := net.ListenPacket("udp4", listenAddr)

if err3 != nil {

alertMsg = bsutils.CreateFormattedBSAlert(bsutils.ALERT_CRITICAL, "ListenPacket Failed: %s", err3.Error())

return nil, alertMsg

}

mConn := ipv4.NewPacketConn(inetConn)

if err := mConn.JoinGroup(iFace, &net.UDPAddr{IP: grpAddress}); err != nil {

alertMsg = bsutils.CreateFormattedBSAlert(bsutils.ALERT_CRITICAL, "JoinGroup Failed: %s", err.Error())

return nil, alertMsg

}

If it gets past the above code, I then do a SetControlMessage and return mConn for normal serving.

thanks,

Paul

[Pierre Durand]

Did you test Go 1.9 betas or RCs ?

[oldCoderException]

No.  I just downloaded and used 1.9 on its release last week.  I've reverted to 1.8.3 for now and, as mentioned, it's working fine for me.

[Jason E. Aten]

https://github.com/golang/go/issues

I don't see an existing issue for this. I would file one with details about how to reproduce.

[James Bardin]

On Sunday, August 27, 2017 at 7:36:22 PM UTC-4, oldCoderException wrote:

No.  I just downloaded and used 1.9 on its release last week.  I've reverted to 1.8.3 for now and, as mentioned, it's working fine for me.

Are you certain you also have the latest version of golang.org/x/net/ipv4? 

[Paul Stead]

Excellent catch James!  I looked, and it seems my x/net/ipv4 files were all from 2015.  I forced an update of those using go get -u, and things seem good now.  I'll need a way to ensure things get updated more completely going forward I guess.

thank you.

Paul

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[Harley Laue]

Might be a good excuse to try deposit (https://github.com/golang/dep) 

I think

$ dep ensure -update

Might be roughly what you would have wanted in this case.

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