Apparently there's an intermittent condition in tests that follows this path.
We used to ignore unrecognized states, but to improve test coverage I added a
clause to catch them, and now that clause is happening where I didn't expect
it.
* Previously, we only connected to the relay supplied by our partner, which
meant that if our relay differed from theirs, we'd never connect
* But we must de-duplicate the relays because when our relay *is* the same as
theirs, we'd have two copies, which means two connections. Now that we
deliver sided handshakes, we can tolerate that (previously, our two
connections would be matched with each other), but it's still wasteful.
This also fixes our handling of relay hints to accept multiple specific
endpoints in each RelayHint. The idea here is that we might know multiple
addresses for a single relay (maybe one IPv4, one IPv6, a Tor .onion, and an
I2P address). Any one connection is good enough, and the connections we can
try depend upon what local interfaces we discover. So a clever implementation
could refrain from making some of those connections when it knows the sibling
hints are just as good. However we might still have multiple relays entirely,
for which it is *not* sufficient to connect to just one.
The change is to create and process RelayV1Hint objects properly, and to set
the connection loop to try every endpoint inside each RelayV1Hint. This is
not "clever" (we could nominally make fewer connection attempts), but it's
plenty good for now.
refs #115
fix relay hints
The appveyor tests were failing because their VMs only have 127.0.0.1,
and stripping it out resulted in an empty hint list, which meant Transit
couldn't work at all.
This will allow a future peer to figure out what transit modes we can
and cannot do, and thus avoid spinning up expensive modes that we won't
be able to use (e.g. WebRTC).
The file-send protocol now sends a "hints-v1" key in the "transit"
message, which contains a list of JSON data structures that describe the
connection hints (a mixture of direct, tor, and relay hints, for now).
Previously the direct/tor and relay hints were sent in different keys,
and all were sent as strings like "tcp:hostname:1234" which had to be
parsed by the recipient.
The new structures include a version string, to make it easier to add
new types in the future. Transit logs+ignores hints it cannot
understand.
