remove full iface access assumption [linux/bsd]

[willscott]

fix #8

[Stebalien]

Ok, well, upgrading something along the way has exposed the actual error. We're getting an index out of bounds error.

[Stebalien]

Failed
=== RUN   TestRoute
--- FAIL: TestRoute (0.00s)
panic: runtime error: index out of range [4619] with length 2 [recovered]
	panic: runtime error: index out of range [4619] with length 2

goroutine 6 [running]:
testing.tRunner.func1.1(0x5447e0, 0xc000016920)
	/usr/local/go/src/testing/testing.go:941 +0x3d0
testing.tRunner.func1(0xc000022240)
	/usr/local/go/src/testing/testing.go:944 +0x3f9
panic(0x5447e0, 0xc000016920)
	/usr/local/go/src/runtime/panic.go:967 +0x166
github.com/libp2p/go-netroute.(*router).RouteWithSrc(0xc0000ac1e0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0xc00001a3d0, 0x10, 0x10, ...)
	/home/circleci/project/common.go:103 +0x7e2
github.com/libp2p/go-netroute.(*router).Route(0xc0000ac1e0, 0xc00001a3d0, 0x10, 0x10, 0x10, 0x10, 0x1, 0x0, 0xc0000ea358, 0x4, ...)
	/home/circleci/project/common.go:82 +0x96
github.com/libp2p/go-netroute.TestRoute(0xc000022240)
	/home/circleci/project/netroute_test.go:51 +0x4af
testing.tRunner(0xc000022240, 0x55ff40)
	/usr/local/go/src/testing/testing.go:992 +0xdc
created by testing.(*T).Run
	/usr/local/go/src/testing/testing.go:1043 +0x357

[Stebalien]

We probably need to use a map instead of an array.

[willscott]

tests passing is good. I'll merge & cut a release now to not block your downstream work. Take a look and confirm when you get a chance.

[Stebalien]

nit: We should probably pre-allocate these.