Age | Commit message (Collapse) | Author |
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Wen DnsQuestion objects are used for DnsQuery objects all contained keys
have to share the same name, but otherwise they generally don't have to,
and this can actually happen in real-life because DnsPacket objects for
mDNS use DnsQuestion for the question section.
Hence, rename:
dns_question_is_valid() to dns_question_is_valid_for_query(), since the
name uniqueness check it does is only relevant when used for a query.
Similar, rename dns_question_name() to dns_question_first_name(),
to be more accurate, as this difference matters if we keys don#t have to
share the same name.
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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.
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Takes a key and CNAME RR and returns the canonical RR of the right
type. Make use of this in dns_question_redirect().
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So far we handled immediate "no server" query results differently from
"no server" results we ran into during operation: the former would cause
the dns_query_go() call to fail with ESRCH, the later would result in
the query completion callback to be called.
Remove the duplicate codepaths, by always going through the completion
callback. This allows us to remove quite a number of lines for handling
the ESRCH.
This commit should not alter behaviour at all.
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We do so for Unicast DNS and LLMNR anyway, let's also do this for mDNS,
and simplify things.
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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.
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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.
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Let's make sure that clients querying resolved via the bus for A, AAAA
or PTR records for "localhost" get a synthesized, local reply, so that
we do not hit the network.
This makes part of nss-myhostname redundant, if used in conjunction.
However, given that nss-resolve shall be optional we need to keep this
code in both places for now.
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This patch removes includes that are not used. The removals were found with
include-what-you-use which checks if any of the symbols from a header is
in use.
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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.
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something up
Also, return on which protocol/family/interface we found something.
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based on cached data
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and timeing out transactions
That way the cache doens't get confused when the system is suspended.
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transactions on the same scope, nowhere else
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spec
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responses
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responses
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connection by default
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Name defending is still missing.
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hence let's not generate that
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different clients
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records
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Let's turn resolved into a something truly useful: a fully asynchronous
DNS stub resolver that subscribes to network changes.
(More to come: caching, LLMNR, mDNS/DNS-SD, DNSSEC, IDN, NSS module)
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