Either suppress the entry entirely, or not at all. But do not suppress
the "localhost" names we recognize, leaving the ones we do not in place.
On Fedora, where "localhost4.localdomain4" is among those listed in
/etc/hosts for 127.0.0.1 we'd thus otherwise drop the "localhost" but
keep the "localhost4.localdomain4" and then on reverse lookups only
return that, which is highly confusing.
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.
It's not that I think that "hostname" is vastly superior to "host name". Quite
the opposite — the difference is small, and in some context the two-word version
does fit better. But in the tree, there are ~200 occurrences of the first, and
>1600 of the other, and consistent spelling is more important than any particular
spelling choice.
On certain distributions such as NixOS the mtime of `/etc/hosts` is
locked to a fixed value. In such cases, only checking the last mtime of
`/etc/hosts` is not enough - we also need to check if the st_ino/st_dev
match up. Thus, let's make sure make sure that systemd-resolved also
rereads `/etc/hosts` if the inode or the device containing `/etc/hosts` changes.
Test script:
```bash
hosts="/etc/hosts"
echo "127.0.0.1 testpr" > "hosts_new"
mv "hosts_new" "$hosts"
resolvectl query testpr || exit 1
mtime="$(stat -c %y "$hosts")"
echo "127.0.0.1 newhost" > "hosts_tmp"
touch -d "$mtime" "hosts_tmp"
install -p "hosts_tmp" "$hosts"
sleep 10
resolvectl query newhost || exit 1
rm -f "hosts_tmp"
```
Closes#14456.
In subsequent commits, calls to if_nametoindex() will be replaced by a wrapper
that falls back to alternative name resolution over netlink. netlink support
requires libsystemd (for sd-netlink), and we don't want to add any functions
that require netlink in basic/. So stuff that calls if_nametoindex() for user
supplied interface names, and everything that depends on that, needs to be
moved.
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.
Do not treat various errors (missing hostname, invalid address) as fatal,
just warn and continue. /etc/hosts is written by humans and we should not
reject the whole file just because a singly entry is not to our liking.
Handle comments as described in hosts(5):
everything from the comment character until the end of the line should be
ignored.
Fixes#10779.
Add tests.
Ideally, coccinelle would strip unnecessary braces too. But I do not see any
option in coccinelle for this, so instead, I edited the patch text using
search&replace to remove the braces. Unfortunately this is not fully automatic,
in particular it didn't deal well with if-else-if-else blocks and ifdefs, so
there is an increased likelikehood be some bugs in such spots.
I also removed part of the patch that coccinelle generated for udev, where we
returns -1 for failure. This should be fixed independently.
All users of the macro (except for one, in serialize.c), use the macro in
connection with read_line(), so they must include fileio.h. Let's not play
libc games and require multiple header file to be included for the most common
use of a function.
The removal of def.h includes is not exact. I mostly went over the commits that
switch over to use read_line() and add def.h at the same time and reverted the
addition of def.h in those files.
The choice what errors to ignore is left to the caller, and the caller is
changed to ignore all errors.
On error, previously read data is kept. So if e.g. an oom error happens, we
will continue to return slightly stale data instead of pretending we have no
entries for the given address. I think that's better, for example when
/etc/hosts contains some important overrides that external DNS should not be
queried for.
We'd store every 0.0.0.0 and ::0 entry as a structure without any addresses
allocated. This is a somewhat common use case, let's optimize it a bit.
This gives some memory savings and a bit faster response time too:
'time build/test-resolved-etc-hosts hosts' goes from 7.7s to 5.6s, and
memory use as reported by valgrind for ~10000 hosts is reduced
==18097== total heap usage: 29,902 allocs, 29,902 frees, 2,136,437 bytes allocated
==18240== total heap usage: 19,955 allocs, 19,955 frees, 1,556,021 bytes allocated
Also rename 'suppress' to 'found' (with reverse meaning). I think this makes
the intent clearer.
This hides the details of juggling the two hashmaps from the callers a bit.
It also makes memory management a bit easier, because those two hashmaps share
some strings, so we can only free them together.
etc_hosts_parse() is made responsible to free the half-filled data structures
on error, which makes the caller a bit simpler.
No functional change. A refactoring to prepare for later changes.
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.
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.
Fix wrong condition test in manager_etc_hosts_lookup(), which caused it to
return an IPv4 answer when an IPv6 question was asked, and vice versa.
Also only return success if we actually found any A or AAAA record.
In systemd-resolved.service(8), point out that /etc/hosts mappings only
affect address-type lookups, not other types.
The test case currently disables DNSSEC in resolved, as there is a bug
where "-t MX" fails due to "DNSSEC validation failed" even after
"downgrading to non-DNSSEC mode". This should be dropped once that bug
gets fixed.
Fixes#4801
Throughout the tree there's spurious use of spaces separating ++ and --
operators from their respective operands. Make ++ and -- operator
consistent with the majority of existing uses; discard the spaces.
Lennart Poettering