tree-wide: remove Emacs lines from all files This should be handled fine now by .dir-locals.el, so need to carry that stuff in every file.

resolved: properly handle LLMNR/TCP connection errors The LLMNR spec suggests to do do reverse address lookups by doing direct LLMNR/TCP connections to the indicated address, instead of doing any LLMNR multicast queries. When we do this and the peer doesn't actually implement LLMNR this will result in a TCP connection error, which we need to handle. In contrast to most LLMNR lookups this will give us a quick response on whether we can find a suitable name. Report this as new transaction state, since this should mostly be treated like an NXDOMAIN rcode, except that it's not one.

resolved: when we get a TCP connection failure, try again Previously, when we couldn't connect to a DNS server via TCP we'd abort the whole transaction using a "connection-failure" state. This change removes that, and counts failed connections as "lost packet" events, so that we switch back to the UDP protocol again.

tree-wide: sort includes in *.h This is a continuation of the previous include sort patch, which only sorted for .c files.

tree-wide: make macros for converting fds to pointers and back generic and use them everywhere

util-lib: move fdname_is_valid() to fd-util.[ch]

util-lib: split out fd-related operations into fd-util.[ch] There are more than enough to deserve their own .c file, hence move them over.