ssdp discovery fails with IPV6 addrs

[skhavari]

ssdpUnicastDiscoverImpl & ssdpMulticastDiscoverImpl depend on IPV4 address but don't ensure IPV4 addresses are used.

The code currently grabs the first entry returned by net.Interface.Addrs() and on my machine the following is returned:

Addr[0] = fe80::72cd:60ff:fef3:75ad/64
Addr[1] = 192.168.1.68/24

Since the first entry is an IPV6 entry the code issues a panic and fails to complete discovery.

[ianr0bkny]

Hi Sam,

Thanks for the report. I'll take a look at this. I remember writing
that code and thinking that I would have to revisit it later!

--Ian

On 06/24/2014 03:03 PM, Sam Khavari wrote:

|ssdpUnicastDiscoverImpl| & |ssdpMulticastDiscoverImpl| depend on IPV4
address but don't ensure IPV4 addresses are used.

The code currently grabs the first entry returned by
|net.Interface.Addrs()| and on my machine the following is returned:

|Addr[0] = fe80::72cd:60ff:fef3:75ad/64
Addr[1] = 192.168.1.68/24
|

Since the first entry is an IPV6 entry the code issues a panic and
fails to complete discovery.

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#2.

[skhavari]

I managed to get by this by disabling IPV6 on mac using the instructions here http://help.unc.edu/help/how-do-i-disable-ipv6-on-mac-os-x/.

Disabling IPV6 and re-enabling it pushes the IPV6 entry to the bottom of the Addrs() array.

[ianr0bkny]

I've checked in a patch that should accept IPv4 or IPv6 [my code was accepting IPv4 only]. If you get a chance, please let me know if it works for you. Thanks.

[skhavari]

i'll give it a shot later this afternoon and let you know how it goes.

[skhavari]

that didn't seem to do it

panic: listen udp [fe80::72cd:60ff:fef3:75ad]:13104: bind: can't assign requested address

goroutine 1 [running]:
runtime.panic(0x3176a0, 0xc210046680)
    /usr/local/go/src/pkg/runtime/panic.c:266 +0xb6
github.com/ianr0bkny/go-sonos/ssdp.(*ssdpDefaultManager).ssdpDiscoverImpl(0xc210039a20, 0x363bf0, 0x3, 0x35aa90, 0x5, ...)
    $GOPATH/src/github.com/ianr0bkny/go-sonos/ssdp/ssdp.go:903 +0xd5
github.com/ianr0bkny/go-sonos/ssdp.(*ssdpDefaultManager).Discover(0xc210039a20, 0x363bf0, 0x3, 0x35aa90, 0x5, ...)
    $GOPATH/src/github.com/ianr0bkny/go-sonos/ssdp/ssdp.go:329 +0x70
github.com/ianr0bkny/go-sonos.Discover(0x363bf0, 0x3, 0x35aa90, 0x5, 0x868708, ...)
    $GOPATH/src/github.com/ianr0bkny/go-sonos/sonos.go:247 +0x9e
main.discoverSonos()
    $PROJ_PATH/sonos.go:22 +0xb7
main.main()
    $PROJ_PATH/sonos.go:103 +0x30
exit status 2

[skhavari]

The IPV6 address on this mac test machine is a link-local address and needs to be qualified with a source address or zone. on mac/linux this needs to be qualified with the interface name it belongs to...

eg:
net.JoinHostPort(ipaddr.IP.String()+"%en0", TEST_DISCOVER_PORT)

with that change, the call to ListenUDP succeeds. Fun.

[skhavari]

on mac this does the trick

qualified_ipaddr := ipaddr.IP.String()
if ipaddr.IP.IsLinkLocalMulticast() == true || ipaddr.IP.IsLinkLocalUnicast() {
    qualified_ipaddr = ipaddr.IP.String() + ifi.Name
}
addr_port := net.JoinHostPort(qualified_ipaddr, TEST_DISCOVER_PORT)

[skhavari]

finding more IPV6 related issues. Modified my local build to pick up the first IPV4 address and things are working great.

[ianr0bkny]

Thanks for digging into this. I'm going to have to set-up an IPv6
address on a VMware machine and see if I can't shake out some of these bugs!

On 06/26/2014 09:21 PM, Sam Khavari wrote:

finding more IPV6 related issues. Modified my local build to pick up
the first IPV4 address and things are working great.

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#2 (comment).

[skhavari]

As a VMware employee and share holder, many thanks.

[borje]

Any progress in this issue? I have the same problem on my macbook.

[raggi]

Is there any reason not to support a global listener? I'd be fine with this for my use case.

[dsully]

+1 - I could use a fix here.