scansion tests: Allow specifying network backend via environment variable To make it easier to test select and event without having to edit the config file, e.g. in CI. make integration-test PROSODY_NETWORK_BACKEND=event

net.server_epoll: Prevent stack overflow of opportunistic writes net.http.files serving a big enough file on a fast enough connection with opportunistic_writes enabled could trigger a stack overflow through repeatedly serving more data that immediately gets sent, draining the buffer and triggering more data to be sent. This also blocked the server on a single task until completion or an error. This change prevents nested opportunistic writes, which should prevent the stack overflow, at the cost of reduced download speed, but this is unlikely to be noticeable outside of Gbit networks. Speed at the cost of blocking other processing is not worth it, especially with the risk of stack overflow.

mod_http_errors: Set status code 200 from root page It isn't quite an error.

mod_http_errors: Add a Prosody logo to root page

mod_http_errors: Allow adding icons on error pages

net.http: Send entire HTTP request header as one write When opportunistic writes are enabled this reduces the number of syscalls and TCP packets sent on the wire. Experiments with TCP Fast Open made this even more obvious. That table trick probably wasn't as efficient. Lua generates bytecode for a table with zero array slots and space for two entries in the hash part, plus code to set [2] and [4]. I didn't verify but I suspect it would have had to resize the table when setting [1] and [3], although probably only once. Concatenating the strings directly in Lua is easier to read and involves no extra table or function call.

net.server_epoll: Immediately attempt to read from newly accepted connections This may speed up client-first protocols (e.g. XMPP, HTTP and TLS) when the first client data already arrived by the time we accept() it. If LuaSocket supported TCP_DEFER_ACCEPT we could use that to further increase the chance that there's already data to handle. In case no data has arrived, no harm should be done, :onreadable would simply set the read timeout and we'll get back to it once there is something to handle.

net.server_epoll: Separate handling of new incoming and outgoing connections The :init method is more suited for new outgoing connections, which is why it uses the connect_timeout setting. Depending on whether a newly accepted connection is to a Direct TLS port or not, it should be handled differently, and was already. The :starttls method sets up timeouts on its own, so the one set in :init was not needed. Newly accepted plain TCP connections don't need a write timeout set, a read timeout is enough.

net.server_epoll: Ensure timeout after closing This should make sure that if there's data left to be written when closing a connection, there's also a timeout so that it doesn't wait forever.

core.loggingmanager: Disable pretty printing when not connected to a tty Things can behave unexpectedly when fed ANSI escape codes.