It is possible to request routes to invalid public keys.

[evanlinjin]

Describe the bug
It is possible to request routes to invalid public keys. The current example is to empty public keys.

[2020-02-29T01:07:24+08:00] INFO [router]: Requesting new routes from 031b80cd5773143a39d940dc0710b93dcccc262a85108018a7a95ab9af734f8055 to 000000000000000000000000000000000000000000000000000000000000000000
[2020-02-29T01:07:34+08:00] INFO [skychat.v1.0[ERROR]]: time="2020-02-29T01:07:34+08:00" level=warning msg="route finder: transport not found" source="retrier.go:68"

Environment:

• skywire-services@feature/m3-dmsgpty-hypervisor
• skywire-mainnet@evanlinjin:feature/m3-dmsgpty-hypervisor
• dmsg@mainnet-milestone2

Steps to Reproduce

1. Run the generic integration environment.
2. Run make integration-startup to setup transports.
3. Open http://localhost:8000/ in browser and type a random message. Check logs of associated visor.

Actual behavior

[2020-02-29T01:07:24+08:00] INFO [router]: Requesting new routes from 031b80cd5773143a39d940dc0710b93dcccc262a85108018a7a95ab9af734f8055 to 000000000000000000000000000000000000000000000000000000000000000000
[2020-02-29T01:07:34+08:00] INFO [skychat.v1.0[ERROR]]: time="2020-02-29T01:07:34+08:00" level=warning msg="route finder: transport not found" source="retrier.go:68"

Expected behavior
The visor shouldn't waste time with such new routes.

Possible implementation
Look in router (maybe).

[evanlinjin]

Similar errors are found in route finder as well:

[2020-02-29T01:17:00+08:00] ERROR [RF]: Error creating graph for src 000000000000000000000000000000000000000000000000000000000000000000 error="transport not found"