Apparently it can EAGAIN on non-blocking connections... I don't think
LibreSSL's TLS library does this, but something to keep in mind if it
doesn't work for somebody.
tls_read() and tls_write() may return TLS_WANT_POLLIN or TLS_WANT_POLLOUT
if data isn't ready to be read or written yet. We have to account for this
by converting it to EAGAIN, which is how a typical read() or write()
function should behave.
Also installed a SIGPIPE handler; we do not want to be terminated by
SIGPIPE, and it's safe to ignore this signal because it should be
handled thoroughly in the code.
This is useful for having a TLS and a non-TLS version port, like Synapse.
I verified that the multiple-servers does in fact work as intended,
although the TLS server part is broken; I must be doing something
incorrectly with LibreSSL in setting up the server.
This way, we can still set the debug level in the configuration, and not
see the log just absolutely flooded with memory allocations and whatnot.
This is helpful because I want debug messages to show up in development,
but not in production, but having all the memory logging makes it
almost impossible to pick anything else out of the log. I want the
feature available, just not on by default because it's useful in limited
circumstances.
The standard use case for this is going to be running a TLS and a non-TLS
HTTP server. I can't see a need for *more* than two, but it is theoretically
possible.
We shouldn't have to change anything with the database or anything; it
should suffice to simply spin up more HTTP servers, and they should
interact with each other the same way a single HTTP server with multiple
threads will.
This is the easiest and cleanest way to get logging into some of the
fundamental APIs, such as the database and TLS APIs. We don't want to
have to pass logging functions to those, but they can safely use the
global logging configuration.
Not only does this make us more POSIX, it actually makes things a lot
easier because TLS implementations will need to be able to access the
trusted certificates file, which most likely will not live in the
data directory.
