resolved: include inttypes.h in resolved-def.h given that we use UINT64_C

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: add packet header details for mDNS Validate mDNS queries and responses by looking at some header fields, add mDNS flags.

resolved: add a concept of "authenticated" responses This adds a new SD_RESOLVED_AUTHENTICATED flag for responses we return on the bus. When set, then the data has been authenticated. For now this mostly reflects the DNSSEC AD bit, if DNSSEC=trust is set. As soon as the client-side validation is complete it will be hooked up to this flag too. We also set this bit whenver we generated the data ourselves, for example, because it originates in our local LLMNR zone, or from the built-in trust anchor database. The "systemd-resolve-host" tool has been updated to show the flag state for the data it shows.

resolved: change query flag definitions Let's use a more useful way to write the flags. Also, leave some space in the middle for the mDNS flags. After all, these flags are exposed on the bus, and we should really make sure to expose flags that are going to be stable, hence allow some room here... (Not that the room really mattered, except to be nice to one's OCD)

resolved: fully support DNS search domains This adds support for searching single-label hostnames in a set of configured search domains. A new object DnsQueryCandidate is added that links queries to scopes. It keeps track of the search domain last used for a query on a specific link. Whenever a host name was unsuccessfuly resolved on a scope all its transactions are flushed out and replaced by a new set, with the next search domain appended. This also adds a new flag SD_RESOLVED_NO_SEARCH to disable search domain behaviour. The "systemd-resolve-host" tool is updated to make this configurable via --search=. Fixes #1697

resolved: add ResolveService() bus call for resolving SRV and DNS-SD services This also adds client-side support for this to systemd-resolve-host. Note that the ResolveService() API can deal both with DNS-SD service (consisting of service name, type and domain), as well as classic SRV services (consisting just of a type and a domain), all exposed in the same call. This patch also reworks CNAME handling in order to reuse it between hostname, RR and service lookups. In contrast to Avahi and Bonjour, this new API will actually reolve the A/AAAA RRs the SRV RRs point to in one go (unless this is explicitly disabled). This normally comes for free, as these RRs are sent along the SRV responses anyway, hence let's make use of that. This makes the API considerably easier to use, as a single ResolveService() invocation will return all necessary data to pick a server and connect() to it. Note that this only implements the DNS-SD resolving step, it does not implement DNS-SD browsing, as that makes sense primarily on mDNS, due to its continuous nature.

resolved: allow passing on which protocol, family and interface to look something up Also, return on which protocol/family/interface we found something.