Admittedly, some of our glyphs _are_ special, e.g. "O=" for SPECIAL_GLYPH_TOUCH ;)
But we don't need this in the name. The very long names make some invocations
very wordy, e.g. special_glyph(SPECIAL_GLYPH_SLIGHTLY_UNHAPPY_SMILEY).
Also, I want to add GLYPH_SPACE, which is not special at all.
Commit 1be9b30a3b ("dhcp6: use dns_name_from_wire_format") introduced a
stricter validation of domains received via DHCPv6, by using function
dns_name_from_wire_format() which rejects the domain when it is missing the
terminating zero label. According to RFC 4704 § 4.2, DHCPv6 servers should
always add the zero label:
To send a fully qualified domain name, the Domain Name field is set
to the DNS-encoded domain name including the terminating zero-length
label. To send a partial name, the Domain Name field is set to the
DNS-encoded domain name without the terminating zero-length label.
[...]
Servers SHOULD send the complete fully qualified domain name in
Client FQDN options.
In practice, there is at least on common DHCPv6 server implementation (dnsmasq)
that sends the FQDN option without the ending zero-length label; after
upgrading to the new systemd, the client cannot parse the option and therefore
the machine doesn't get the hostname provided by dnsmasq.
This commit restores the old behavior that considers a domain valid even when
it's missing the terminating zero label.
Here's a quick reproducer:
--8<--
ip link add veth0 type veth peer name veth1
ip netns add ns1
ip link set veth1 netns ns1
ip link set veth0 address 00:11:22:33:44:55
ip link set veth0 up
ip -n ns1 link set veth1 up
ip -n ns1 address add dev veth1 fd01::1/64
ip netns exec ns1 dnsmasq \
--pid-file=/tmp/dnsmasq.pid --no-hosts \
--bind-interfaces --interface veth1 --except-interface lo \
--dhcp-range=fd01::100,fd01::200 --enable-ra \
--dhcp-host 00:11:22:33:44:55,foobar &
cat <<EOF > /etc/systemd/network/veth0.network
[Match]
Name=veth0
[Network]
DHCP=ipv6
EOF
networkctl reload
networkctl up veth0
sleep 5
hostname
--8<--
Without this change, systemd-networkd prints the following message and doesn't
set the hostname from DHCP:
veth0: DHCPv6 client: Failed to parse FQDN option, ignoring: Bad message
Currently, when comparing two DNS names when storing them in a
hashtable, and the DNS names are not actually valid we'll compare the
error codes.
This is not very smart however, since this means two invalid DNS names
that happen to be equally "invalid" will be considered identical, even
if their strings are entirely different.
Let's find a better solution for this niche case: let's simple compare
the domains as strings.
This matters in case of DNS label compression: if we already added added
an invalid DNS name into the label compression hash table, and lookup
any other invalid DNS name, this lookup will likely return what the
earlier one already returned, and that's confusing.
This is just paranoia. In all these cases we don't really care about the
trailing NUL byte. But if there's space for it dns_label_unescape() is
going to insert it, and that's a good safety strategy.
This is a follow-up to c29c3adefa8cd859f8cb87d9ad62f3d77b7cd102 which
fixed an actual bug, unlike this commit, which is just paranoia.
From RFC 9476:
Because names beneath .alt are in an alternative namespace, they have no
significance in the regular DNS context. DNS stub and recursive
resolvers do not need to look them up in the DNS context.
See: https://datatracker.ietf.org/doc/html/rfc9476#name-the-alt-namespace
The article "a" goes before consonant sounds and "an" goes before vowel
sounds. This commit changes an to a for UKI, UDP, UTF-8, URL, UUID, U-Label, UI
and USB, since they start with the sound /ˌjuː/.
We now have a local implementation in string-util-fundamental.c, but
it's useful at a lot of other places, hence let's give it a more
expressive name and share it across the tree.
Follow-up for: 8d9156660d
dns_label_unescape() does not nul-terminate the buffer if it does not
have enough space. Hence, if a lable is enough long, then strjoin()
triggers buffer-overflow.
Fixes#23705.
Let's define two helpers strdupa_safe() + strndupa_safe() which do the
same as their non-safe counterparts, except that they abort if called
with allocations larger than ALLOCA_MAX.
This should ensure that all our alloca() based allocations are subject
to this limit.
afaics glibc offers three alloca() based APIs: alloca() itself,
strndupa() + strdupa(). With this we have now replacements for all of
them, that take the limit into account.
We recently started making more use of malloc_usable_size() and rely on
it (see the string_erase() story). Given that we don't really support
sytems where malloc_usable_size() cannot be trusted beyond statistics
anyway, let's go fully in and rework GREEDY_REALLOC() on top of it:
instead of passing around and maintaining the currenly allocated size
everywhere, let's just derive it automatically from
malloc_usable_size().
I am mostly after this for the simplicity this brings. It also brings
minor efficiency improvements I guess, but things become so much nicer
to look at if we can avoid these allocation size variables everywhere.
Note that the malloc_usable_size() man page says relying on it wasn't
"good programming practice", but I think it does this for reasons that
don't apply here: the greedy realloc logic specifically doesn't rely on
the returned extra size, beyond the fact that it is equal or larger than
what was requested.
(This commit was supposed to be a quick patch btw, but apparently we use
the greedy realloc stuff quite a bit across the codebase, so this ends
up touching *a*lot* of code.)
https://tools.ietf.org/html/rfc1035#section-2.3.1 says (approximately)
that only letters, numbers, and non-leading non-trailing dashes are allowed
(for entries with A/AAAA records). We set no restrictions.
hosts(5) says:
> Host names may contain only alphanumeric characters, minus signs ("-"), and
> periods ("."). They must begin with an alphabetic character and end with an
> alphanumeric character.
nss-files follows those rules, and will ignore names in /etc/hosts that do not
follow this rule.
Let's follow the documented rules for /etc/hosts. In particular, this makes us
consitent with nss-files, reducing surprises for the user.
I'm pretty sure we should apply stricter filtering to names received over DNS
and LLMNR and MDNS, but it's a bigger project, because the rules differ
depepending on which level the label appears (rules for top-level names are
stricter), and this patch takes the minimalistic approach and only changes
behaviour for /etc/hosts.
Escape syntax is also disallowed in /etc/hosts, even if the resulting character
would be allowed. Other tools that parse /etc/hosts do not support this, and
there is no need to use it because no allowed characters benefit from escaping.
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.
Zbigniew Jędrzejewski-Szmek
Beniamino Galvani
Lennart Poettering
Integral
Ronan Pigott
Michal Sekletar
Bertrand Jacquin
Joerg Behrmann
Yu Watanabe
David Tardon
Luca Boccassi
Frantisek Sumsal
Thomas Haller
Filipe Brandenburger