https://tools.ietf.org/html/rfc5891#section-4.2.3.1 says that
> The Unicode string MUST NOT contain "--" (two consecutive hyphens) in the third
> and fourth character positions and MUST NOT start or end with a "-" (hyphen).
This means that libidn2 refuses to encode such names.
Let's just resolve them without trying to use IDN.
Actually the caller of dns_packet_new() pass 0 or the data size of the UDP message.
So try to reflect that, so rename the `mtu` parameter to `min_alloc_dsize`.
In fact `mtu` is the size of the whole UDP message, including the UDP header,
and here we just need to pass the size of data (without header). This was confusing.
Also add a check on the requested allocated size, since some caller do not check what is really allocated.
Indeed the function do not allocate more than DNS_PACKET_SIZE_MAX whatever the value of the `mtu` parameter.
As suggested in:
496ae8c84b (commitcomment-22819483)
Let's drop some noise from the logs, as switching between DNS servers is
definitely useful for debugging, but shouldn't get more attention that
that.
dns_packet_new() is sometimes called with mtu == 0, and in that case we should
allocate more than the absolute minimum (which is the dns packet header size),
otherwise we have to resize immediately again after appending the first data to
the packet.
This partially reverts the previous commit.
When DNS is unreliable temporarily, the current implementation will
never improve resend behavior again and switch DNS servers only late
(current maximum timeout is 5 seconds).
We can improve this by biasing the resend_timeout back to the current
RTT when a successful response was received. Next time, a timeout is hit
on this server, it will switch to the next server faster.
Fixes: #5953
The allocation size was calculated in a complicated way, and for values
close to the page size we would actually allocate less than requested.
Reported by Chris Coulson <chris.coulson@canonical.com>.
CVE-2017-9445
libidn2 2.0.0 supports IDNA2008, in contrast to libidn which supports IDNA2003.
https://bugzilla.redhat.com/show_bug.cgi?id=1449145
From that bug report:
Internationalized domain names exist for quite some time (IDNA2003), although
the protocols describing them have evolved in an incompatible way (IDNA2008).
These incompatibilities will prevent applications written for IDNA2003 to
access certain problematic domain names defined with IDNA2008, e.g., faß.de is
translated to domain xn--fa-hia.de with IDNA2008, while in IDNA2003 it is
translated to fass.de domain. That not only causes incompatibility problems,
but may be used as an attack vector to redirect users to different web sites.
v2:
- keep libidn support
- require libidn2 >= 2.0.0
v3:
- keep dns_name_apply_idna caller dumb, and keep the #ifdefs inside of the
function.
- use both ±IDN and ±IDN2 in the version string
Since all our python scripts have a proper python3 shebang, there is no benefit
to letting meson autodetect them. On linux, meson will just uses exec(), so the
shebang is used anyway. The only difference should be in how meson reports the
script and that the detection won't fail for (most likely misconfigured)
non-UTF8 locales.
Closes#5855.
Using conf.set() with a boolean argument does the right thing:
either #ifdef or #undef. This means that conf.set can be used unconditionally.
Previously I used '1' as the placeholder value, and that needs to be changed to
'true' for consistency (under meson 1 cannot be used in boolean context). All
checks need to be adjusted.
This is useful on systems like NixOS, where python3 is not in
/usr/bin/python3 as well as for people using alternative ways to
install python such as virtualenv/pyenv.
Also detect libgpg-error. Require both to be present for HAVE_CRYPT,
even though libgpg-error is only used in src/resolve. If one is available,
the other should be too, so it doesn't seem worth the trouble to make two
separate conditions.
The indentation for emacs'es meson-mode is added .dir-locals.
All files are reindented automatically, using the lasest meson-mode from git.
Indentation should now be fairly consistent.
This simplifies things and leads to a smaller installation footprint.
libsystemd_internal and libsystemd_journal_internal are linked into
libystemd-shared and available to all programs linked to libsystemd-shared.
libsystemd_journal_internal is not needed anymore, and libsystemd-shared
is used everwhere. The few exceptions are: libsystemd.so, test-engine,
test-bus-error, and various loadable modules.
With mesonbuid/meson#1545, meson does not propagate deps of a library
when linking with that library. That's of course the right thing to do,
but it exposes a bunch of missing deps.
This compiles with both meson-0.39.1 and meson-git + pr/1545.
Tests can be run with 'ninja-build test' or using 'mesontest'.
'-Dtests=unsafe' can be used to include the "unsafe" tests in the
test suite, same as with autotools.
v2:
- use more conf.get guards are optional components
- declare deps on generated headers for test-{af,arphrd,cap}-list
v3:
- define environment for tests
Most test don't need this, but to be consistent with autotools-based build, and
to avoid questions which tests need it and which don't, set the same environment
for all tests.
v4:
- rework test generation
Use a list of lists to define each test. This way we can reduce the
boilerplate somewhat, although the test listings are still pretty verbose. We
can also move the definitions of the tests to the subdirs. Unfortunately some
subdirs are included earlier than some of the libraries that test binaries
are linked to. So just dump all definitions of all tests that cannot be
defined earlier into src/test. The `executable` definitions are still at the
top level, so the binaries are compiled into the build root.
v5:
- tag test-dnssec-complex as manual
v6:
- fix HAVE_LIBZ typo
- add missing libgobject/libgio defs
- mark test-qcow2 as manual
It's crucial that we can build systemd using VS2010!
... er, wait, no, that's not the official reason. We need to shed old systems
by requring python 3! Oh, no, it's something else. Maybe we need to throw out
345 years of knowlege accumulated in autotools? Whatever, this new thing is
cool and shiny, let's use it.
This is not complete, I'm throwing it out here for your amusement and critique.
- rules for sd-boot are missing. Those might be quite complicated.
- rules for tests are missing too. Those are probably quite simple and
repetitive, but there's lots of them.
- it's likely that I didn't get all the conditions right, I only tested "full"
compilation where most deps are provided and nothing is disabled.
- busname.target and all .busname units are skipped on purpose.
Otherwise, installation into $DESTDIR has the same list of files and the
autoconf install, except for .la files.
It'd be great if people had a careful look at all the library linking options.
I added stuff until things compiled, and in the end there's much less linking
then in the old system. But it seems that there's still a lot of unnecessary
deps.
meson has a `shared_module` statement, which sounds like something appropriate
for our nss and pam modules. Unfortunately, I couldn't get it to work. For the
nss modules, we need an .so version of '2', but `shared_module` disallows the
version argument. For the pam module, it also didn't work, I forgot the reason.
The handling of .m4 and .in and .m4.in files is rather awkward. It's likely
that this could be simplified. If make support is ever dropped, I think it'd
make sense to switch to a different templating system so that two different
languages and not required, which would make everything simpler yet.
v2:
- use get_pkgconfig_variable
- use sh not bash
- use add_project_arguments
v3:
- drop required:true and fix progs/prog typo
v4:
- use find_library('bz2')
- add TTY_GID definition
- define __SANE_USERSPACE_TYPES__
- use join_paths(prefix, ...) is used on all paths to make them all absolute
v5:
- replace all declare_dependency's with []
- add more conf.get guards around optional components
v6:
- drop -pipe, -Wall which are the default in meson
- use compiler.has_function() and compiler.has_header_symbol instead of the
hand-rolled checks.
- fix duplication in 'liblibsystemd' library name
- use the right .sym file for pam_systemd
- rename 'compiler' to 'cc': shorter, and more idiomatic.
v7:
- use ENABLE_ENVIRONMENT_D not HAVE_ENVIRONMENT_D
- rename prefix to prefixdir, rootprefix to rootprefixdir
("prefix" is too common of a name and too easy to overwrite by mistake)
- wrap more stuff with conf.get('ENABLE...') == 1
- use rootprefix=='/' and rootbindir as install_dir, to fix paths under
split-usr==true.
v8:
- use .split() also for src/coredump. Now everything is consistent ;)
- add rootlibdir option and use it on the libraries that require it
v9:
- indentation
v10:
- fix check for qrencode and libaudit
v11:
- unify handling of executable paths, provide options for all progs
This makes the meson build behave slightly differently than the
autoconf-based one, because we always first try to find the executable in the
filesystem, and fall back to the default. I think different handling of
loadkeys, setfont, and telinit was just a historical accident.
In addition to checking in $PATH, also check /usr/sbin/, /sbin for programs.
In Fedora $PATH includes /usr/sbin, (and /sbin is is a symlink to /usr/sbin),
but in Debian, those directories are not included in the path.
C.f. https://github.com/mesonbuild/meson/issues/1576.
- call all the options 'xxx-path' for clarity.
- sort man/rules/meson.build properly so it's stable
This is our own header, we should include use the local-include syntax
("" not <>), to make it clear we are including the one from the build tree.
All other includes of files from src/systemd/ use this scheme.
Previously, `SO_REUSEADDR` is set before `bind`-ing socket, Thus,
even if another LLMNR stack is running, `bind` always success and
we cannot detect the other stack. By this commit, we first try to
`bind` without `SO_REUSEADDR`, and if it fails, show warning and
retry with `SO_REUSEADDR`.
Previously, `SO_REUSEADDR` is set before `bind`-ing socket, Thus,
even if another mDNS stack (e.g. avahi) is running, `bind` always
success and we cannot detect the other stack.
By this commit, we first try to `bind` without `SO_REUSEADDR`,
and if it fails, show warning and retry with `SO_REUSEADDR`.
When no network enables LLMNR or mDNS, it is not necessary to create
LLMNR or mDNS related sockets. So, let's create them only when
LLMNR- or mDNS-enabled network becomes active or at least one network
enables `LLMNR=` or `MulticastDNS=` options.
For caching negative replies we need the SOA TTL information. Hence,
let's authenticate all auxiliary SOA RRs through DS requests on all
negative requests.
Let's increase a number of timeouts as they apparently are too short for
some real-world lookups.
See:
https://github.com/systemd/systemd/issues/4003#issuecomment-279842616
In particular we change the following timeouts:
1) The first UDP retry we increase 500ms → 750ms. This is a good idea,
since some servers need relatively long responses for trivial lookups,
and giving up our first attempt also has the effect of trying a
different server for the next attempt which has the side effect that
we'll run two down-grade iterations in parallel, on both servers.
Hence, let's give servers a bit more time in the first iteration.
2) Permit 24 retries instead of just 16 per transactions. If we end up
downgrading all the way down to UDP for a lookup we already need 5
iterations for that. If we want permit a couple of lost packages for
each (let's say 4), then we already need 20 iterations.
3) Increase the overall query timeout on the service side to 60s (from
45s), simply because very long and slow DNSSEC + CNAME chains (such as
us.ynuf.alipay.com) hit this boundary too easily. The client side
timeout for the bus method call is increased to 90s, in order to have
room for the dbus reply to go through
Following our coding style on success we should initialize all return
parameters of a function. We missed to cases for dns_cache_lookup() (but
covered all others), fix them too.
This is the most important piece of information of replies, hence show
this in the first log message about it.
(Wireshark shows it too in the short summary, hence this definitely
makes sense...)
Retrying a transaction via TCP is a good approach for mitigating
packet loss. However, it's not a good away way to fix a bad RCODE if we
already downgraded to UDP level for it. Hence, don't do this.
This is a small tweak only, but shortens the time we spend on
downgrading when a specific domain continously returns a bad rcode.
Some domains (such as us.ynuf.alipay.com) almost appear as if they actively
want to sabotage our DNSSEC work. Specifically, they unconditionally
return SERVFAIL on SOA lookups and always only after a 1s delay (at
least). This is pretty bad for our validation logic, as we use SOA
lookups to distuingish zones from non-terminal names. Moreover, SERVFAIL
is an error that is typically returned if we send requests a server
doesn't grok, and thus is reason for us to downgrade our protocol and
try again. In case of these zones this means we'll accept the SERVFAIL
response only after a full iterative downgrade to our lowest feature
level: TCP. In combination with the 1s delays this has the effect of
making us hit our transaction timeout way to easily.
As first attempt to improve the situation: let's start caching SERVFAIL
responses in our cache, after the full downgrade for a short period of
time.
Conceptually this is exposed as "weird rcode" caching, but for now we
only consider SERVFAIL a "weird rcode" worthy of caching. Later on we
might want to add more.
When we are doing a TCP transaction the kernel will automatically resend
all packets for us, there's no need to do that ourselves. Hence:
increase the timeout for TCP transactions substantially, to give the
kernel enough time to connect to the peer, without interrupting it when
we become impatient.
