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*.localdomain != localhost

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".localdomain" is not a reserved suffix (or prefix). I'm not aware of any
product expecting *.localdomain to resolve to localhost, however I am aware of
at least one product that defaults to ".localdomain" as its DNS suffix provided
via DHCP (pfSense). This leads to unexpected results when attempting to access
a host that's offline (or a host that's online, when nsswitch.conf is
[mis-]configured to have myhostname ahead of DNS).

Operate on:
localhost (and localhost.)
*.localhost (and *.localhost.)
localhost.localdomain (and localhost.localdomain.)
*.localhost.localdomain (and *.localhost.localdomain.)

We should not cover:
*.localdomain (nor *.localdomain.)
localdomain (nor localdomain.)
This commit is contained in:
David R. Hedges 2016-02-18 21:31:38 -06:00 committed by Zbigniew Jędrzejewski-Szmek
parent 48ddca5f35
commit 63003524cb
3 changed files with 13 additions and 11 deletions
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7
man/nss-myhostname.xml
View file

@ -71,9 +71,10 @@
is on the local loopback) and the IPv6 address ::1 (which is the
local host).</para></listitem>
<listitem><para>The hostname <literal>localhost</literal> (as well as any hostname ending in
<literal>.localhost</literal>, <literal>.localdomain</literal> or equal to <literal>localdomain</literal>) is
resolved to the IP addresses 127.0.0.1 and ::1.</para></listitem>
<listitem><para>The hostnames <literal>localhost</literal> and
<literal>localhost.localdomain</literal> (as well as any hostname
ending in <literal>.localhost</literal> or <literal>.localhost.localdomain</literal>)
are resolved to the IP addresses 127.0.0.1 and ::1.</para></listitem>
<listitem><para>The hostname <literal>gateway</literal> is
resolved to all current default routing gateway addresses,

7
man/systemd-resolved.service.xml
View file

@ -87,9 +87,10 @@
is on the local loopback) and the IPv6 address ::1 (which is the
local host).</para></listitem>
<listitem><para>The hostname <literal>localhost</literal> (as well as any hostname ending in
<literal>.localhost</literal>, <literal>.localdomain</literal> or equal to <literal>localdomain</literal>) is
resolved to the IP addresses 127.0.0.1 and ::1.</para></listitem>
<listitem><para>The hostnames <literal>localhost</literal> and
<literal>localhost.localdomain</literal> (as well as any hostname
ending in <literal>.localhost</literal> or <literal>.localhost.localdomain</literal>)
are resolved to the IP addresses 127.0.0.1 and ::1.</para></listitem>
<listitem><para>The hostname <literal>gateway</literal> is
resolved to all current default routing gateway addresses,

10
src/basic/hostname-util.c
View file

@ -150,16 +150,16 @@ bool is_localhost(const char *hostname) {
assert(hostname);
/* This tries to identify local host and domain names
* described in RFC6761 plus the redhatism of .localdomain */
* described in RFC6761 plus the redhatism of localdomain */
return strcaseeq(hostname, "localhost") ||
strcaseeq(hostname, "localhost.") ||
strcaseeq(hostname, "localdomain.") ||
strcaseeq(hostname, "localdomain") ||
strcaseeq(hostname, "localhost.localdomain") ||
strcaseeq(hostname, "localhost.localdomain.") ||
endswith_no_case(hostname, ".localhost") ||
endswith_no_case(hostname, ".localhost.") ||
endswith_no_case(hostname, ".localdomain") ||
endswith_no_case(hostname, ".localdomain.");
endswith_no_case(hostname, ".localhost.localdomain") ||
endswith_no_case(hostname, ".localhost.localdomain.");
}
bool is_gateway_hostname(const char *hostname) {