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: internalize string buffer of dns_resource_record_to_string() Let's simplify usage and memory management of DnsResourceRecord's dns_resource_record_to_string() call: cache the formatted string as part of the object, and return it on subsequent calls, freeing it when the DnsResourceRecord itself is freed.

resolved: make use of dns_{class|type}_is_{pseudo|valid_rr}() everywhere

resolved: add support NSEC3 proofs, as well as proofs for domains that are OK to be unsigned This large patch adds a couple of mechanisms to ensure we get NSEC3 and proof-of-unsigned support into place. Specifically: - Each item in an DnsAnswer gets two bit flags now: DNS_ANSWER_AUTHENTICATED and DNS_ANSWER_CACHEABLE. The former is necessary since DNS responses might contain signed as well as unsigned RRsets in one, and we need to remember which ones are signed and which ones aren't. The latter is necessary, since not we need to keep track which RRsets may be cached and which ones may not be, even while manipulating DnsAnswer objects. - The .n_answer_cachable of DnsTransaction is dropped now (it used to store how many of the first DnsAnswer entries are cachable), and replaced by the DNS_ANSWER_CACHABLE flag instead. - NSEC3 proofs are implemented now (lacking support for the wildcard part, to be added in a later commit). - Support for the "AD" bit has been dropped. It's unsafe, and now that we have end-to-end authentication we don't need it anymore. - An auxiliary DnsTransaction of a DnsTransactions is now kept around as least as long as the latter stays around. We no longer remove the auxiliary DnsTransaction as soon as it completed. THis is necessary, as we now are interested not only in the RRsets it acquired but also in its authentication status.

resolved: chase DNSKEY/DS RRs when doing look-ups with DNSSEC enabled This adds initial support for validating RRSIG/DNSKEY/DS chains when doing lookups. Proof-of-non-existance, or proof-of-unsigned-zones is not implemented yet. With this change DnsTransaction objects will generate additional DnsTransaction objects when looking for DNSKEY or DS RRs to validate an RRSIG on a response. DnsTransaction objects are thus created for three reasons now: 1) Because a user asked for something to be resolved, i.e. requested by a DnsQuery/DnsQueryCandidate object. 2) As result of LLMNR RR probing, requested by a DnsZoneItem. 3) Because another DnsTransaction requires the requested RRs for validation of its own response. DnsTransactions are shared between all these users, and are GC automatically as soon as all of these users don't need a specific transaction anymore. To unify the handling of these three reasons for existance for a DnsTransaction, a new common naming is introduced: each DnsTransaction now tracks its "owners" via a Set* object named "notify_xyz", containing all owners to notify on completion. A new DnsTransaction state is introduced called "VALIDATING" that is entered after a response has been receieved which needs to be validated, as long as we are still waiting for the DNSKEY/DS RRs from other DnsTransactions. This patch will request the DNSKEY/DS RRs bottom-up, and then validate them top-down. Caching of RRs is now only done after verification, so that the cache is not poisoned with known invalid data. The "DnsAnswer" object gained a substantial number of new calls, since we need to add/remove RRs to it dynamically now.

resolved: optionally, allocate DnsResourceKey objects on the stack Sometimes when looking up entries in hashmaps indexed by a DnsResourceKey it is helpful not having to allocate a full DnsResourceKey dynamically just to use it as search key. Instead, optionally allow allocation of a DnsResourceKey on the stack. Resource keys allocated like that of course are subject to other lifetime cycles than the usual Resource keys, hence initialize the reference counter to to (unsigned) -1. While we are at it, remove the prototype for dns_resource_key_new_dname() which was never implemented.

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: simplify dns zone logic: take a single key when looking up entries Instead of taking a DnsQuestion object (i.e. an array of keys) only take a single key. This simplifies things a bit, and as DNS/LLMNR require a single question per query message was unnecessary anyway. This mimics a similar change that was done a while ago for the dns cache logic.

util-lib: split out allocation calls into alloc-util.[ch]

util-lib: split our string related calls from util.[ch] into its own file string-util.[ch] There are more than enough calls doing string manipulations to deserve its own files, hence do something about it. This patch also sorts the #include blocks of all files that needed to be updated, according to the sorting suggestions from CODING_STYLE. Since pretty much every file needs our string manipulation functions this effectively means that most files have sorted #include blocks now. Also touches a few unrelated include files.

tree-wide: take benefit of the fact that hashmap_free() returns NULL And set_free() too. Another Coccinelle patch.

resolved: dump cache and zone contents to syslog on SIGUSR1

resolved: only maintain one question RR key per transaction Let's simplify things and only maintain a single RR key per transaction object, instead of a full DnsQuestion. Unicast DNS and LLMNR don't support multiple questions per packet anway, and Multicast DNS suggests coalescing questions beyond a single dns query, across the whole system.

resolved: rework synthesizing logic With this change we'll now also generate synthesized RRs for the local LLMNR hostname (first label of system hostname), the local mDNS hostname (first label of system hostname suffixed with .local), the "gateway" hostname and all the reverse PTRs. This hence takes over part of what nss-myhostname already implemented. Local hostnames resolve to the set of local IP addresses. Since the addresses are possibly on different interfaces it is necessary to change the internal DnsAnswer object to track per-RR interface indexes, and to change the bus API to always return the interface per-address rather than per-reply. This change also patches the existing clients for resolved accordingly (nss-resolve + systemd-resolve-host). This also changes the routing logic for queries slightly: we now ensure that the local hostname is never resolved via LLMNR, thus making it trustable on the local system.

resolve: move dns routines into shared

treewide: no need to negate errno for log_*_errno() It corrrectly handles both positive and negative errno values.

treewide: auto-convert the simple cases to log_*_errno() As a followup to 086891e5c1 "log: add an "error" parameter to all low-level logging calls and intrdouce log_error_errno() as log calls that take error numbers", use sed to convert the simple cases to use the new macros: find . -name '*.[ch]' | xargs sed -r -i -e \ 's/log_(debug|info|notice|warning|error|emergency)\("(.*)%s"(.*), strerror\(-([a-zA-Z_]+)\)\);/log_\1_errno(-\4, "\2%m"\3);/' Multi-line log_*() invocations are not covered. And we also should add log_unit_*_errno().

hashmap: introduce hash_ops to make struct Hashmap smaller It is redundant to store 'hash' and 'compare' function pointers in struct Hashmap separately. The functions always comprise a pair. Store a single pointer to struct hash_ops instead. systemd keeps hundreds of hashmaps, so this saves a little bit of memory.

resolved: initialize counter introduced in: a407657425a3e47fd2b559cd3bc800f791303f63

resolved: actually, the peer with the lower IP address wins conflicts

resolved: make sure we don't mark the wrong zone RRs conflicting

resolved: be a bit more communicative about conflicts

resolved: verify all RRs when we come back from suspend

resolved: implement full LLMNR conflict detection logic

resolved: properly check return value of dns_resource_record_equal()

resolved: stop the prober when we detect a conflict in LLMNR

resolved: don't override zone item state after starting the probe After all, the probe might be finished immeidately (due to resources, ...), and we shouldn't then set the state back to probing.

resolved: never reuse transactions for probing that are already completed based on cached data

resolved: if there's already an RR established that has the same name of an RR to be established, skip probing the name After all, what has been probed once, doesn't need to be probed again.

resolved: implement LLMNR uniqueness verification

resolved: properly set TTL in SOA records

resolved: include SOA records in LLMNR replies for non-existing RRs to allow negative caching

resolved: respond to ANY queries from our zone

resolved: don't allow adding of ANY class/type RRs to local zones

resolve: add llmnr responder side for UDP and TCP Name defending is still missing.