Libp2p fails to determine default route on FreeBSD

[Stebalien]

On FreeBSD, netroute.Router.Route('0.0.0.0') returns an error instead of returning the default route. We need some other way to determine the default route. We could just try looking up a well known IP address.

go-libp2p/p2p/host/basic/basic_host.go

Lines 260 to 280 in 6a3b138

	if r, err := netroute.New(); err != nil {
	log.Debugw("failed to build Router for kernel's routing table", "err", err)
	} else {
	if _, _, localIPv4, err := r.Route(net.IPv4zero); err != nil {
	log.Debugw("failed to fetch local IPv4 address", "err", err)
	} else {
	maddr, err := manet.FromIP(localIPv4)
	if err == nil {
	h.localIPv4Addr = maddr
	}
	}
	if _, _, localIpv6, err := r.Route(net.IPv6unspecified); err != nil {
	log.Debugw("failed to fetch local IPv6 address", "err", err)
	} else {
	maddr, err := manet.FromIP(localIpv6)
	if err == nil {
	h.localIPv6Addr = maddr
	}
	}
	}

[willscott]

what error do you get? I'm guessing you're able to load the routing table, but asking for the route is failing?

[Stebalien]

"no route found for 0.0.0.0"

[willscott]

just to confirm, you're specifically referring to FreeBSD, and not macs, right?

[Stebalien]

I am. I haven't tested on MacOS.

[willscott]

spun up a FreeBSD VM and can't reproduce:

FreeBSD 12.1-RELEASE r354233 GENERIC  amd64

The RIB's returned by the system call are:

rtNFO: &{10.0.2.15/0 0.0.0.0/0 10.0.2.2 10.0.2.15 0 1 0}
rtNFO: &{10.0.2.15/32 10.0.2.0/24 <nil> 10.0.2.15 0 1 0}
rtNFO: &{127.0.0.1/32 10.0.2.15/32 <nil> 127.0.0.1 0 2 0}
rtNFO: &{127.0.0.1/32 127.0.0.1/32 <nil> 127.0.0.1 0 2 0}
rtNFO: &{::1/128 ::1/128 <nil> ::1 0 2 0}
rtNFO: &{fe80::1/128 fe80::/64 <nil> fe80::1 0 2 0}
rtNFO: &{fe80::1/128 fe80::1/128 <nil> fe80::1 0 2 0}

(em0 network interface 10.0.2.15/24 with gw 10.0.2.2)
default route works as expected in this case.

I think to debug / reproduce, the most useful thing to do would be to modify here to insert the line fmt.Printf("rtNFO: %v", routeInfo)
so that we can try to understand what's happening with regards to the parsed routing table.

[gammazero]

Cannot reproduce
FreeBSD 14.1-RELEASE releng/14.1-n267679-10e31f0946d8 GENERIC amd64

Printing route info here shows results similary to above. Default route is found.

Maybe this issue was reported on a host that only has IPv6 addresses and no default route was found for 0.0.0.0?

In either case, this does not seem to be a defect (or has not been for a long time), so suggest closing this issue.

[Stebalien]

It had an IPv4 address. But this was a long time ago on a machine that no longer exists (and was probably in a FreeBSD jail). Given that nobody can reproduce, I'm just going to close this.