Back in 5248e7e1f1 (July 2017) we moved over to
"_gateway", with the old name declared to be temporary measure. Since we're
doing a bunch of changes to resolved now, it seems to be a good moment to make
this simplification and not add support for the compat name in new code.
Make them rather fail than go to the network.
Previously we'd filter them on LLMNR (explicitly) and MDNS (implicitly,
because it doesn't have .local suffix), but not on DNS.
In order to make _gateway truly reliable, let's not allow it to go to
DNS either, and keep it local.
This is particular relevant, as clients can now request lookups without
local RR synthesis, where we'd rather have NXDOMAIN returned for
_gateway than have it hit the network.
Apparently, IF_UNICAST_IF does not influence the routing decisions done
during connect(). But SO_BINDTODEVICE/SO_BINDTOINDEX does, which however
brings a lot of other semantics with it, we are not so interested in
(i.e. it doesn't not allow packets from any other iface to us, even if
routing otherwise allows it).
Hence, let's bind to the ifindex immediately before the connect() and
unbind right after again, so that we get the semantics we want, but not
the ones we don't.
Fixes: #11935
Replaces: #12004
A variety of sockopts exist both for IPv4 and IPv6 but require a
different pair of sockopt level/option number. Let's add helpers for
these that internally determine the right sockopt to call.
This should shorten code that generically wants to support both ipv4 +
ipv6 and for the first time adds correct support for some cases where we
only called the ipv4 versions, and not the ipv6 options.
Patch contains a coccinelle script, but it only works in some cases. Many
parts were converted by hand.
Note: I did not fix errors in return value handing. This will be done separate
to keep the patch comprehensible. No functional change is intended in this
patch.
Previously, we'd use a link as "default" route depending on whether
there are route-only domains defined on it or not. (If there are, it
would not be used as default route, if there aren't it would.)
Let's make this explicit and add a link variable controlling this. The
variable is not changeable from the outside yet, but subsequent commits
are supposed to add that.
Note that making this configurable adds a certain amount of redundancy,
as there are now two ways to ensure a link does not receive "default"
lookup (i.e. DNS queries matching no configured route):
1. By ensuring that at least one other link configures a route on it
(for example by add "." to its search list)
2. By setting this new boolean to false.
But this is exactly what is intended with this patch: that there is an
explicit way to configure on the link itself whether it receives
'default' traffic, rather than require this to be configured on other
links.
The variable added is a tri-state: if true, the link is suitable for
recieving "default" traffic. If false, the link is not suitable for it.
If unset (i.e. negative) the original logic of "has this route-only
routes" is used, to ensure compatibility with the status quo ante.
The function dns_server_limited_domains() was very strange as it
enumerate the domains associated with a DnsScope object to determine
whether any "route-only" domains, but did so as a function associated
with a DnsServer object.
Let's clear this up, and replace it by a function associated with a
DnsScope instead. This makes more sense philosphically and allows us to
reduce the loops through which we need to jump to determine whether a
scope is suitable for default routing a bit.
Previously, we'd return DNS_SCOPE_MAYBE for all domain lookups matching
LLMNR or mDNS. Let's upgrade this to DNS_SCOPE_YES, to make the binding
stronger.
The effect of this is that even if "local" is defined as routing domain
on some iface, we'll still lookup domains in local via mDNS — if mDNS is
turned on. This should not be limiting, as people who don't want such
lookups should turn off mDNS altogether, as it is useless if nothing is
routed to it.
This also has the nice benefit that mDNS/LLMR continue to work if people
use "~." as routing domain on some interface.
Similar for LLMNR and single label names.
Similar also for the link local IPv4 and IPv6 reverse lookups.
Fixes: #10125
This information is useful to pass back to the caller, as it tells us
where we found the answer.
(While we are at it, fix the socket level for the RECVERR logic)
Fixes: #9778
All over the place we define local variables for the various sockopts
that take a bool-like "int" value. Sometimes they are const, sometimes
static, sometimes both, sometimes neither.
Let's clean this up, introduce a common const variable "const_int_one"
(as well as one matching "const_int_zero") and use it everywhere, all
acorss the codebase.
This fixes the following valgrind warning:
```
Syscall param sendmsg(msg.msg_name) points to uninitialised byte(s)
at 0x6189CC1: sendmsg (in /usr/lib64/libpthread-2.27.so)
by 0x153082: dns_stream_writev (resolved-dns-stream.c:235)
by 0x153343: dns_stream_tls_writev (resolved-dns-stream.c:299)
by 0x5B30343: ??? (in /usr/lib64/libgnutls.so.30.20.2)
by 0x5B3158F: ??? (in /usr/lib64/libgnutls.so.30.20.2)
by 0x5B33190: ??? (in /usr/lib64/libgnutls.so.30.20.2)
by 0x5B36307: ??? (in /usr/lib64/libgnutls.so.30.20.2)
by 0x5B37D47: gnutls_handshake (in /usr/lib64/libgnutls.so.30.20.2)
by 0x154591: dns_stream_connect_tls (resolved-dns-stream.c:596)
by 0x13A889: dns_transaction_emit_tcp (resolved-dns-transaction.c:676)
by 0x13D901: dns_transaction_go (resolved-dns-transaction.c:1761)
by 0x1330C8: dns_query_candidate_go (resolved-dns-query.c:156)
Address 0xa9ac268 is 312 bytes inside a block of size 592 alloc'd
at 0x4C30B06: calloc (vg_replace_malloc.c:711)
by 0x1541F8: dns_stream_new (resolved-dns-stream.c:545)
by 0x13A662: dns_transaction_emit_tcp (resolved-dns-transaction.c:642)
by 0x13D901: dns_transaction_go (resolved-dns-transaction.c:1761)
by 0x1330C8: dns_query_candidate_go (resolved-dns-query.c:156)
by 0x134E16: dns_query_go (resolved-dns-query.c:757)
by 0x11F3FB: bus_method_resolve_hostname (resolved-bus.c:353)
by 0x4F947A7: method_callbacks_run (bus-objects.c:402)
by 0x4F97266: object_find_and_run (bus-objects.c:1260)
by 0x4F978B1: bus_process_object (bus-objects.c:1376)
by 0x4FAF82C: process_message (sd-bus.c:2661)
by 0x4FAFA1B: process_running (sd-bus.c:2703)
```
These lines are generally out-of-date, incomplete and unnecessary. With
SPDX and git repository much more accurate and fine grained information
about licensing and authorship is available, hence let's drop the
per-file copyright notice. Of course, removing copyright lines of others
is problematic, hence this commit only removes my own lines and leaves
all others untouched. It might be nicer if sooner or later those could
go away too, making git the only and accurate source of authorship
information.
This part of the copyright blurb stems from the GPL use recommendations:
https://www.gnu.org/licenses/gpl-howto.en.html
The concept appears to originate in times where version control was per
file, instead of per tree, and was a way to glue the files together.
Ultimately, we nowadays don't live in that world anymore, and this
information is entirely useless anyway, as people are very welcome to
copy these files into any projects they like, and they shouldn't have to
change bits that are part of our copyright header for that.
hence, let's just get rid of this old cruft, and shorten our codebase a
bit.
When I see "test", I have to think three times what the return value
means. With "below" this is immediately clear. ratelimit_below(&limit)
sounds almost like English and is imho immediately obvious.
(I also considered ratelimit_ok, but this strongly implies that being under the
limit is somehow better. Most of the times this is true, but then we use the
ratelimit to detect triple-c-a-d, and "ok" doesn't fit so well there.)
C.f. a1bcaa07.
Files which are installed as-is (any .service and other unit files, .conf
files, .policy files, etc), are left as is. My assumption is that SPDX
identifiers are not yet that well known, so it's better to retain the
extended header to avoid any doubt.
I also kept any copyright lines. We can probably remove them, but it'd nice to
obtain explicit acks from all involved authors before doing that.
This is similar to TAKE_PTR() but operates on file descriptors, and thus
assigns -1 to the fd parameter after returning it.
Removes 60 lines from our codebase. Pretty good too I think.
Enumerating DNS-SD PTR resource records are a special case and
are supposed to have non-unique keys pointing to services of the
same type running on different hosts. There's no need for them
to be checked for conflicts.
Thus don't check for conflicts such RRs.
Refcounting for a RR's key is done separately from refcounting
for the RR itself, but in dns_scope_notify_conflict() we don't
do that. This may lead to a situation when a RR key put in the
conflict_queue hash as a value's key gets freed upon
cache reduction when it's still referenced by the hash.
Thus increase refcount for the key when putting it into the hash
and unreference it upon removing from the hash.
Closes#6456
Currently, we accept SERVFAIL after downgrading fully, cache it and move
on. Let's extend this a bit: after downgrading fully, if the SERVFAIL
logic continues to be an issue, then use a different DNS server if there
are any.
Fixes: #7147
This makes sure that a classic DNS scope that has no DNS servers
assigned is never considered for routing requests to even if it has
matching search/routing domains associated.
This is inspired by #7544, where lookup requests are refused since a
scope with no DNS server is configured. This change does not deliver
what the reporter intended, but is generally useful in general, as it
makes us mor robust to misconfiguration.
It might happen that a DNS-SD service doesn't include local host's
name in its RR keys and still conflicts with a remote service.
In this case try to resolve the conflict by changing name for
this particular service.