The existing code was largely set up for SN-to-SN or client-to-SN
communications, where messages can always get to the right place because
we can always send by pubkey.
This doesn't work when we want general communications with a random
remote address.
This commit overhauls the way loki-mq handles communication in a few
important ways:
- Listening instances no longer pass bind addresses into the
constructor; instead they call `listen_curve()` or `listen_plain()`
before invoking `start()`.
- `listen_curve()` is equivalent to the existing bind support: it
listens on a socket and accepts encrypted handshaked connections from
anyone who already knows the server's public key.
- `listen_plain()` is all new: it sets up a plain text listening socket
over which random clients can connect and talk. End-points aren't
verified, and it isn't encrypted, but if you don't know who you are
talking to then encryption isn't doing anything anyway.
- Connecting to a remote now connections in CURVE encryption or NULL
(plain-text) encryption based on whether you provide a remote_pubkey.
For CURVE, the connection will fail if the pubkey does not match.
- `ConnectionID` objects are now returned when connecting to a remote
address; this object is then passed in to send/request/etc. to direct
the message. For SN communication, ConnectionID's can be created
implicitly from SN pubkey strings, so the existing interface of
`lmq.send(pubkey, ...)` will still work in most cases.
- A ConnectionID is now passed to the ConnectSuccess and ConnectFailure
callbacks. This can be used to uniquely identify which connection
succeeded or failed, and can determine whether the remote is a service
node (`.sn()`) and/or the pubkey (`.pubkey()`). (Obviously the service
node status is only available when the client can do service node
lookups, and the pubkey() is only non-empty for encrypted connections).
string_view isn't supposed to be implicitly convertible to std::string
and code would break compiling under c++17 (when our local string_view
is simply a std::string_view typedef).
Batch jobs scheduled by the proxy thread itself were delayed to the next
poll timeout (because nothing ever gets sent on a socket). Add a
variable to bypass the next poll to handle this case.
Jason Rhinelander