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man: import org.freedesktop.resolve1(3) from the wiki

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<?xml version="1.0"?>
<!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [
<!ENTITY % entities SYSTEM "custom-entities.ent" >
%entities;
]>
<!-- SPDX-License-Identifier: LGPL-2.1+ -->
<refentry id="org.freedesktop.resolve1" conditional='ENABLE_RESOLVE'
xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>org.freedesktop.resolve1</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>org.freedesktop.resolve1</refentrytitle>
<manvolnum>5</manvolnum>
</refmeta>
<refnamediv>
<refname>org.freedesktop.resolve1</refname>
<refpurpose>The D-Bus interface of systemd-resolved</refpurpose>
</refnamediv>
<refsect1>
<title>Introduction</title>
<para>
<citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
is a system service that provides host name resolution and caching using DNS, LLMNR, and mDNS. It also
does DNSSEC validation. This page describes the resolve semantics and the D-Bus interface.</para>
<para>This page contains an API reference only. If you are looking for a longer explanation how to use
this API, please consult
<ulink url="https://wiki.freedesktop.org/www/Software/systemd/writing-network-configuration-managers">
Writing Network Configuration Managers</ulink>
and
<ulink url="https://wiki.freedesktop.org/www/Software/systemd/writing-resolver-clients">Writing Resolver
Clients</ulink>.
</para>
</refsect1>
<refsect1>
<title>The Manager Object</title>
<para>The service exposes the following interfaces on the Manager object on the bus:</para>
<programlisting>
$ gdbus introspect --system \
--dest org.freedesktop.resolve1 \
--object-path /org/freedesktop/resolve1
node /org/freedesktop/resolve1 {
interface org.freedesktop.resolve1.Manager {
methods:
ResolveHostname(in i ifindex,
in s name,
in i family,
in t flags,
out a(iiay) addresses,
out s canonical,
out t flags);
ResolveAddress(in i ifindex,
in i family,
in ay address,
in t flags,
out a(is) names,
out t flags);
ResolveRecord(in i ifindex,
in s name,
in q class,
in q type,
in t flags,
out a(iqqay) records,
out t flags);
ResolveService(in i ifindex,
in s name,
in s type,
in s domain,
in i family,
in t flags,
out a(qqqsa(iiay)s) srv_data,
out aay txt_data,
out s canonical_name,
out s canonical_type,
out s canonical_domain,
out t flags);
ResetStatistics();
GetLink(in i ifindex,
out o path);
SetLinkDNS(in i ifindex,
in a(iay) addresses);
SetLinkDomains(in i ifindex,
in a(sb) domains);
SetLinkLLMNR(in i ifindex,
in s mode);
SetLinkMulticastDNS(in i ifindex,
in s mode);
SetLinkDNSSEC(in i ifindex,
in s mode);
SetLinkDNSSECNegativeTrustAnchors(in i ifindex,
in as names);
RevertLink(in i ifindex);
properties:
readonly s LLMNRHostname = 'delta';
readonly a(iiay) DNS = [(0, 2, [0xac, 0x1f, 0x00, 0x01])];
readonly a(isb) Domains = [(0, 'fritz.box', false)];
readonly (tt) TransactionStatistics = (0, 846);
readonly (ttt) CacheStatistics = (55, 406, 439);
readonly (tttt) DNSSECStatistics = (0, 0, 0, 0);
readonly b DNSSECSupported = false;
};
interface org.freedesktop.DBus.Peer {
};
interface org.freedesktop.DBus.Introspectable {
};
interface org.freedesktop.DBus.Properties {
};
};
</programlisting>
<refsect2>
<title>Methods</title>
<para><function>ResolveHostname()</function> takes a hostname and acquires one or more IP addresses for
it. As parameters it takes the Linux network interface index to execute the query on, or 0 if it may be
done on any suitable interface. The <varname>name</varname> parameter specifies the hostname to
resolve. Note that IDNA conversion is applied to this name when necessary, and when it is resolved via
Unicast DNS, but not for resolution via LLMNR or MulticastDNS. The <varname>family</varname> parameter
specifies the address family of the IP address to retrieve. It may be <constant>AF_INET</constant>,
<constant>AF_INET6</constant> or <constant>AF_UNSPEC</constant>, to request addresses of a specific
family. If <constant>AF_UNSPEC</constant> is specified (recommended), both kinds are retrieved, subject
to local network configuration (i.e. if no local, routable IPv6 address is found, no IPv6 address is
retrieved; and similarly for IPv4). A 64-bit <varname>flags</varname> field may be used to alter
behaviour of the resolver operation (see below). The method returns an array of address records. Each
address record consists of an interface index the address belongs to, an address family as well as a
byte array with the actual IP address data (which either has 4 or 16 elements, depending on the address
family). The returned address family will be one of <constant>AF_INET</constant> or
<constant>AF_INET6</constant>. For IPv6, the returned address interface index should be used to
initialize the .sin6_scope_id field of a <structname>struct sockaddr_in6</structname>, to permit
support for resolution to link-local IP addresses. The address array is followed by the canonical name
of the host, which may or may not be identical to the name looked up. Finally, a 64-bit
<varname>flags</varname> field is returned, that is defined similarly to the <varname>flags</varname>
field that was passed in, but contains information about the resolved data (see below). If the hostname
passed in is an IPv4 or IPv6 address formatted as string, it is parsed, and the result returned. In
this case no network communication is done.</para>
<para><function>ResolveAddress()</function> executes the reverse operation: it takes an IP address and
acquires one or more hostnames for it. As parameters it takes the interface index to execute the query
on, or <constant>0</constant> if all suitable interfaces are OK. The <varname>family</varname>
parameter indicates the address family of the IP address to resolve, it may be either
<constant>AF_INET</constant> or <constant>AF_INET6</constant>. The <varname>address</varname> parameter
takes the raw IP address data (as either 4 or 16 byte array). The <varname>flags</varname> input
parameter may be used to alter the resolver operation (see below). The call returns an array of name
records, consisting of an interface index plus the name each. The <varname>flags</varname> output
field contains additional information about the resolver operation (see below).</para>
<para><function>ResolveRecord()</function> takes a DNS resource record (RR) type, class and name, and
retrieves the full resource record set (RRset), including the RDATA, for it. As parameter it takes the
Linux network interface index to execute the query on, or <constant>0</constant> if it may be done on
any suitable interface. The <varname>name</varname> parameter specifies the RR domain name to look up
(no IDNA conversion is applied), followed by the 16-bit class and type fields (which may be
ANY). Finally, a <varname>flags</varname> field may be passed in to alter behaviour of the look-up (see
below). On return an array of RR items is returned. Each array entry consists of the network interface
index the RR was discovered on, the type and class field of the RR found, and a byte array of the raw
RR discovered. The raw RR data starts with the RR&#39;s domain name, in the original casing, followed
by the RR type, class, TTL and RDATA, in the binary format documented in
<ulink url="https://www.ietf.org/rfc/rfc1035.txt">RFC 1035</ulink>. For RRs that support name
compression in the payload (such as MX or PTR), the compression is expanded in the returned
data.</para>
<para>Note that the class field has to be specified as IN or ANY currently, and specifying a different
class will return an error indicating that look-ups of this kind are unsupported. Similarly, some
special types are not supported either (AXFR, OPT, …). While <filename>systmed-resolved</filename> parses and validates resource
record of many types, it is crucial that clients using this API understand that the RR data originates
from the network and should be thoroughly validated before use.</para>
<para><function>ResolveService()</function> may be used to resolve a DNS SRV service record, as the
hostnames referenced in it, and possibly an accompanying DNS-SD TXT record containing additional
service metadata. The primary benefit of using this call over <function>ResolveRecord()</function>
specifying the SRV type is that it will resolve the SRV and TXT RRs as well as the hostnames referenced
in the SRV in a single operation. As parameters it takes a Linux network interface index, a service
name, a service type and a service domain. The call may be invoked in three different modes:</para>
<orderedlist>
<listitem><para>To resolve a DNS-SD service, specify the service name (e.g. <literal>Lennart&#39;s
Files</literal>), the service type (e.g. <literal>_webdav._tcp</literal>) and the domain to search in
(e.g. <literal>local</literal>) in the three service parameters. The service name must be in UTF-8
format, and no IDNA conversion is applied to it in this mode (as mandated by the DNS-SD
specifications). However, if necessary IDNA conversion is applied to the domain parameter.</para>
</listitem>
<listitem><para>To resolve a plain SRV record, set the service name parameter to the empty string,
and set the service type and domain properly. (IDNA conversion is applied to the domain, if
necessary.)</para></listitem>
<listitem><para>Alternatively, leave both the service name and type empty, and specify the full
domain name of the SRV record (i.e. prefixed with the service type) in the domain parameter. (No IDNA
coversion is applied in this mode.)</para></listitem>
</orderedlist>
<para>The <varname>family</varname> parameter of the <function>ResolveService()</function> call encodes
the desired family of the addresses to resolve (use <constant>AF_INET</constant>,
<constant>AF_INET6</constant>, <constant>AF_UNSPEC</constant>), if this is enabled (Use the
<constant>NO_ADDRESS</constant> flag to turn address resolution off, see below). The
<varname>flags</varname> parameter takes a couple of flags that may be used to alter the resolver
operation.</para>
<para>On return, <function>ResolveService()</function> returns an array of SRV record structures. Each
item consists of the priority, weight and port fields and the hostname to contact, as encoded in the SRV
record. Immediately following is an array with the addresses of this hostname, with each item consisting
of the interface index, the address family and the address data in a byte array. This address array is
followed with the canonicalized hostname. After this array of SRV record structures an array of byte
arrays follows, that encodes the TXT RR strings, in case DNS-SD look-ups are enabled. The next parameters
are the canonical service name, type and domain. This may or may not be identical to the parameters
passed in. Finally, a <varname>flags</varname> field is returned that contains information about the
resolver operation performed.</para>
<para>The <function>ResetStatistics()</function> method resets to zero the various statistics counters
<filename>systmed-resolved</filename> maintains. (For details, see the statistics properties below.)</para>
<para>The <function>GetLink()</function> method takes a network interface index and returns the object
path to the <interfacename>org.freedesktop.resolve1.Link</interfacename> object corresponding to it.
</para>
<para>The <function>SetLinkDNS()</function> method sets the DNS servers to use on a specific
interface. This call (and the following ones) may be used by network management software to configure
per-interface DNS settings. It takes a network interface index as well as an array of DNS server IP
address records. Each array item consists of an address family (either <constant>AF_INET</constant> or
<constant>AF_INET6</constant>), followed by a 4-byte or 16-byte array with the raw address data. This
call is a one-call shortcut for retrieving the Link object for a network interface using
<function>GetLink()</function> (see above) and then invoking the <function>SetDNS()</function> call
(see below) on it.
</para>
<para>Network management software integrating with <filename>systmed-resolved</filename> is recommended
to invoke this method (and the five below) after the interface appeared in the kernel (and thus after a
network interface index has been assigned), but before the network interfaces is activated (set
<constant>IFF_UP</constant> on) so that all settings take effect during the full time the network
interface is up. It is safe to alter settings while the interface is up, however. Use the
<function>RevertLink()</function> (described below) to reset all per-interface settings.</para>
<para>The <function>SetLinkDomains()</function> method sets the search and routing domains to use on a
specific network interface for DNS look-ups. It take a network interface index plus an array of domains,
each with a boolean parameter indicating whether the specified domain shall be used as search domain
(false), or just as routing domain (true). Search domains are used for qualifying single-label names into
FQDN when looking up hostnames, as well as for making routing decisions on which interface to send
queries ending in the domain to. Routing domains are not used for single-label name qualification, and
are only used for routing decisions. Pass the search domains in the order they shall be used.</para>
<para>The <function>SetLinkLLMNR()</function> method enables or disables LLMNR support on a specific
network interface. It takes a network interface index as well as a string that either may be empty,
<literal>yes</literal>, <literal>no</literal> or <literal>resolve</literal>. If empty, the systemd-wide
default LLMNR setting is used. If <literal>yes</literal> LLMNR is used for resolution of single-label
names, and the local hostname is registered on all local LANs for LLMNR resolution by peers. If
<literal>no</literal> LLMNR is turned off fully on this interface. If <literal>resolve</literal> LLMNR
is only enabled for resolving names, but the local host name is not registered for other peers to
use.</para>
<para>Similarly, the <function>SetLinkMulticastDNS()</function> method enables or disables MulticastDNS
support on a specific interface. It takes the same parameters as <function>SetLinkLLMNR()</function>
described above.</para>
<para>The <function>SetLinkDNSSEC()</function> method enables or disables DNSSEC validation on a
specific network interface. It takes a network interface index as well as a string that either may be
empty, <literal>yes</literal>, <literal>no</literal> or <literal>allow-downgrade</literal>. If empty,
the system-wide default DNSSEC setting is used. If <literal>yes</literal> full DNSSEC validation is
done for all look-ups. If the selected DNS server does not support DNSSEC, look-ups will fail if this
mode is used. If <literal>no</literal> DNSSEC validation is fully disabled. If
<literal>allow-downgrade</literal> DNSSEC validation is enabled, but is turned off automatically if the
selected server does not support it (thus opening up behaviour to downgrade attacks). Note that DNSSEC
only applies to traditional DNS, not to LLMNR or MulticastDNS.</para>
<para>The <function>SetLinkDNSSECNegativeTrustAnchors()</function> method may be used to configure DNSSEC
Negative Trust Anchors (NTAs) for a specific network interface. It takes a network interface index and a
list of domains as parameters.</para>
<para>The <function>RevertLink()</function> method may be used to revert all per-link settings done with
the six calls described above to the defaults again.</para>
<refsect3>
<title>The Flags Parameter</title>
<para>The four calls above accept and return a 64-bit flags value. In most cases passing 0 is sufficient
and recommended. However, the following flags are defined to alter the look-up:</para>
<programlisting>
#define SD_RESOLVED_DNS (UINT64_C(1) &lt;&lt; 0)
#define SD_RESOLVED_LLMNR_IPV4 (UINT64_C(1) &lt;&lt; 1)
#define SD_RESOLVED_LLMNR_IPV6 (UINT64_C(1) &lt;&lt; 2)
#define SD_RESOLVED_MDNS_IPV4 (UINT64_C(1) &lt;&lt; 3)
#define SD_RESOLVED_MDNS_IPV6 (UINT64_C(1) &lt;&lt; 4)
#define SD_RESOLVED_NO_CNAME (UINT64_C(1) &lt;&lt; 5)
#define SD_RESOLVED_NO_TXT (UINT64_C(1) &lt;&lt; 6)
#define SD_RESOLVED_NO_ADDRESS (UINT64_C(1) &lt;&lt; 7)
#define SD_RESOLVED_NO_SEARCH (UINT64_C(1) &lt;&lt; 8)
#define SD_RESOLVED_AUTHENTICATED (UINT64_C(1) &lt;&lt; 9)
</programlisting>
<para>On input, the first five flags control the protocols to use for the look-up. They refer to
classic unicast DNS, LLMNR via IPv4/UDP and IPv6/UDP respectively, as well as MulticastDNS via
IPv4/UDP and IPv6/UDP. If all of these five bits are off on input (which is strongly recommended) the
look-up will be done via all suitable protocols for the specific look-up. Note that these flags
operate as filter only, but cannot force a look-up to be done via a protocol. Specifically, <filename>systmed-resolved</filename>
will only route look-ups within the .local TLD to MulticastDNS (plus some reverse look-up address
domains), and single-label names to LLMNR (plus some reverse address lookup domains). It will route
neither of these to Unicast DNS servers. Also, it will do LLMNR and Multicast DNS only on interfaces
suitable for multicasting.</para>
<para>On output these five flags indicate which protocol was used to execute the operation, and hence
where the data was found.</para>
<para>The primary use case for these five flags are follow-up look-ups based on DNS data retrieved
earlier. In this case it is often a good idea to limit the follow-up look-up to the protocol that was
used to discover the first DNS data look-up.</para>
<para>The NO_CNAME flag controls whether CNAME/DNAME resource records shall be followed during the
look-up. This flag is only available at input, none of the functions will return it on output. If a
CNAME/DNAME RR is discovered while resolving a hostname an error is returned instead. By default,
when the flag is off, CNAME/DNAME RRs are followed.</para>
<para>The NO_TXT and NO_ADDRESS flags influence operation of the
<function>ResolveService()</function> call only. They are only defined for input, not output. If
NO_TXT set, the DNS-SD TXT RR look-up is not done in the same operation. If NO_ADDRESS is specified
the hostnames discovered are not implicitly translated to their addresses.</para>
<para>The NO_SEARCH flag turns off the search domain logic. It is only defined for input in
<function>ResolveHostname()</function>. When specified, single-label hostnames are not qualified
using defined search domains, if any are configured. Note that <function>ResolveRecord()</function>
will not qualify single-label domain names using search domains in any case. Also note that
multi-label hostnames are never subject to search list expansion.</para>
<para>The AUTHENTICATED bit is defined only in the output flags of the four functions. If set, the
returned data has been fully authenticated. Specifically, this bit is set for all DNSSEC-protected data
for which a full trust chain may be established to a trusted domain anchor. It is also set for locally
synthesized data, such as <literal>localhost</literal> or data from
<filename>/etc/hosts</filename>. Moreover, it is set for all LLMNR or mDNS RRs which originate from the
local host. Applications that require authenticated RR data for operation should check this flag before
trusting the data. Not that <filename>systmed-resolved</filename> will not return invalidated data in any case, hence this flag
simply allows to discern the cases where data is known to be trustable, or where there is proof that
the data is "rightfully" unauthenticated (which includes cases where the underlying protocol or server
does not support authenticating data).</para>
</refsect3>
</refsect2>
<refsect2>
<title>Properties</title>
<varname>LLMNRHostname</varname> contains the hostname currently exposed on the network via LLMNR. It
usually follows the system hostname as may be queried via
<citerefentry project='man-pages'><refentrytitle>gethostname</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
but may differ if a conflict is detected on the network.
<para><varname>DNS</varname> contains an array containing all DNS servers currently used by
<filename>systmed-resolved</filename>. It contains similar information as the DNS server data written to
/run/systemd/resolve/resolv.conf. Each structure in the array consists of a numeric network interface
index, an address family, and a byte array containing the DNS server address (either 4 bytes in length
for IPv4 or 16 bytes in lengths for IPv6). The array contains DNS servers configured system-wide,
including those possibly read from a foreign <filename>/etc/resolv.conf</filename> or the
<varname>DNS=</varname> setting in <filename>/etc/systemd/resolved.conf</filename>, as well as
per-interface DNS server information either retrieved from
<citerefentry><refentrytitle>systemd-networkd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
or configured by external software via <function>SetLinkDNS()</function> (see above). The network
interface index will be 0 for the system-wide configured services, and non-zero for the per-link
servers.</para>
<para>Similarly, the <varname>Domains</varname> property contains an array containing all search and
routing domains currently used by <filename>systmed-resolved</filename>. Each entry consists of a network interface index (again, 0
encodes system-wide entries), the actual domain name, and whether the entry is used only for routing
(true), or for both routing and searching (false).</para>
<para>The <varname>TransactionStatistics</varname> property contains information about the number of
transactions <filename>systmed-resolved</filename> has been processing. It contains a pair of unsigned 64-bit counters, the first
containing the number of currently ongoing transactions, the second the number of total transactions
<filename>systmed-resolved</filename> is processing or has processed. The latter value may be reset using the
<function>ResetStatistics()</function> call described above. Note that the number of transaction does
not directly map to the number of resolver bus calls issued. While simple look-ups usually require a
single transaction only, more complex look-ups might result in more, for example when CNAMEs or DNSSEC
are in use.</para>
<para>The <varname>CacheStatistics</varname> property contains information about the executed cache
operations so far. It exposes three 64-bit counters: the first being the total number of current cache
entries (both positive and negative), the second number of cache hits, and the third the number of
cache misses. The latter counters may be reset using <function>ResetStatistics()</function> (see
above). </para>
<para>The <varname>DNSSECStatistics</varname> property contains information about the DNSSEC
validations executed so far. It contains four 64-bit counters: the number of secure, insecure, bogus,
and indeterminate DNSSEC validations so far. The counters are increased for each validated RRset, and
each non-existance proof. The secure counter is increased for each operation that successfully verified
a signed reply, the insecure counter is increased for each operation that successfully verified that an
unsigned reply is rightfully unsigned. The bogus counter is increased for each operation where the
validation did not check out, and the data is likely to have been tempered with. Finally the
indeterminate counter is increased for each operation which did not complete because the necessary keys
could not be acquired or the cryptographic algorithms were unknown.</para>
<para>The <varname>DNSSECSupported</varname> boolean property reports whether DNSSEC is enabled and
the selected DNS servers support it. It combines information about system-wide and per-link DNS
settings (see below), and only reports true if DNSSEC is enabled and supported on every interface for
which DNS is configured and for the system-wide settings if there are any. Note that <filename>systmed-resolved</filename> assumes
DNSSEC is supported by DNS servers until it verified that this is not the case. Thus, the reported
value may initially be true, until the first transactions are executed.</para>
</refsect2>
</refsect1>
<refsect1>
<title>Link Object</title>
<programlisting>
$ gdbus introspect --system \
--dest org.freedesktop.resolve1 \
--object-path /org/freedesktop/resolve1/link/_34
node /org/freedesktop/resolve1/link/_34 {
interface org.freedesktop.resolve1.Link {
methods:
SetDNS(in a(iay) arg_0);
SetDomains(in a(sb) arg_0);
SetLLMNR(in s arg_0);
SetMulticastDNS(in s arg_0);
SetDNSSEC(in s arg_0);
SetDNSSECNegativeTrustAnchors(in as arg_0);
Revert();
signals:
properties:
readonly t ScopesMask = 6;
readonly a(iay) DNS = [];
readonly a(sb) Domains = [];
readonly s LLMNR = 'yes';
readonly s MulticastDNS = 'no';
readonly s DNSSEC = '';
readonly as DNSSECNegativeTrustAnchors = [];
readonly b DNSSECSupported = true;
};
interface org.freedesktop.DBus.Peer {
};
interface org.freedesktop.DBus.Introspectable {
};
interface org.freedesktop.DBus.Properties {
};
};
</programlisting>
<para>For each Linux network interface a "Link" object is created, which exposes per-link DNS
configuration and state. Use <function>GetLink()</function> on the Manager interface to retrieve the
object path for a link object given the network interface index (see above).</para>
<refsect2>
<title>Methods</title>
<para>The various methods exposed by the Link interface are equivalent to their similarly named
counterparts on the Manager interface. e.g. <function>SetDNS()</function> on the Link object maps to
<function>SetLinkDNS()</function> on the Manager object, the main difference being that the later
expects an interface index to be speicified. Invoking the calls on the Manager interface has the
benefit of reducing roundtrips, as it is not necessary to first request the Link object path via
<function>GetLink()</function> before invoking the methods. For further details on these calls see the
Manager documentation above. </para>
</refsect2>
<refsect2>
<title>Properties</title>
<para><varname>ScopesMask</varname> defines which resolver scopes are currently active on this
interface. This 64-bit unsigned integer field is a bit mask, consisting of a subset of the bits as the
flags parameter describe above. Specifically, it may have the DNS, LLMNR and MDNS bits (the latter in
IPv4 and IPv6 flavours) set. Each individual bit is set when the protocol applies to a specific
interface and is enabled for it. It is unset otherwise. Specifically, a multicast-capable interface in
"UP" state with an IP address is suitable for LLMNR or MulticastDNS, and any interface that is UP and
has an IP address is suitable for DNS. Note the relationship of the bits exposed here with the LLMNR
and MulticastDNS properties also exposed on the Link interface. The latter expose what is *configured*
to be used on the interface, the former expose what is actually used on the interface, taking into
account the abilities of the interface.</para>
<para><varname>DNSSECSupported</varname> exposes a boolean field that indicates whether DNSSEC is
currently configured and in use on the interface. Note that if DNSSEC is enabled on an interface it is
assumed available until it is detected that the configured server does not actually support it. Thus,
this property may initially report that DNSSEC is supported on an interface.</para>
<para>The other properties reflect the state of the various configuration settings for the link, which
may be set with the various methods calls such as SetDNS() or SetLLMNR().</para>
</refsect2>
</refsect1>
<refsect1>
<title>Common Errors</title>
<para>Many bus calls <filename>systmed-resolved</filename> exposes (in particular the resolver calls such
as <function>ResolveHostname()</function> on the <interfacename>Manager</interfacename> interface) return
some of the following errors:</para>
<variablelist>
<varlistentry><term><constant>org.freedesktop.resolve1.NoNameServers</constant></term>
<listitem><para>No suitable DNS servers have been found to resolve a request.</para></listitem>
</varlistentry>
<varlistentry><term><constant>org.freedesktop.resolve1.InvalidReply</constant></term>
<listitem><para>A response from the selected DNS server could not be understood.</para></listitem>
</varlistentry>
<varlistentry><term><constant>org.freedesktop.resolve1.NoSuchRR</constant></term>
<listitem><para>The requested name exists, but there is no resource record of the requested type for
it. (This is the DNS NODATA case).</para></listitem></varlistentry>
<varlistentry><term><constant>org.freedesktop.resolve1.CNameLoop</constant></term>
<listitem><para>The look-up failed because a CNAME or DNAME loop was detected.</para></listitem>
</varlistentry>
<varlistentry><term><constant>org.freedesktop.resolve1.Aborted</constant></term>
<listitem><para>The look-up was aborted, because the selected protocol became unavailable while the
operation was ongoing.</para></listitem>
</varlistentry>
<varlistentry><term><constant>org.freedesktop.resolve1.NoSuchService</constant></term>
<listitem><para>A service look-up was successful, but the SRV record reported that the service is not
available.</para></listitem></varlistentry>
<varlistentry><term><constant>org.freedesktop.resolve1.DnssecFailed</constant></term>
<listitem><para>The acquired response did not pass DNSSEC validation.</para></listitem>
</varlistentry>
<varlistentry><term><constant>org.freedesktop.resolve1.NoTrustAnchor</constant></term>
<listitem><para>No chain of trust could be established for the response, to a configured DNSSEC trust
anchor.</para></listitem>
</varlistentry>
<varlistentry><term><constant>org.freedesktop.resolve1.ResourceRecordTypeUnsupported</constant></term>
<listitem><para>The requested resource record type is not supported on the selected DNS servers. This
error is generated for example when an RRSIG record is requested from a DNS server that does not
support DNSSEC.</para></listitem>
</varlistentry>
<varlistentry><term><constant>org.freedesktop.resolve1.NoSuchLink</constant></term>
<listitem><para>No network interface with the specified network interface index exists.
</para></listitem></varlistentry>
<varlistentry><term><constant>org.freedesktop.resolve1.LinkBusy</constant></term>
<listitem><para>The requested configuration change can not be made, because
<citerefentry><refentrytitle>systemd-networkd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
already took possession of the interface and supplied configuration data for it.</para></listitem>
</varlistentry>
<varlistentry><term><constant>org.freedesktop.resolve1.NetworkDown</constant></term>
<listitem><para>The requested look-up failed because the system is currently not connected to any
suitable network.</para></listitem></varlistentry>
<varlistentry><term><constant>org.freedesktop.resolve1.DnsError.NXDOMAIN</constant></term>
<term><constant>org.freedesktop.resolve1.DnsError.REFUSED</constant></term>
<term>...</term>
<listitem><para>The look-up failed with a DNS return code reporting a failure. The error names used as
suffixes here are defined in by IANA in
<ulink url="https://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml#dns-parameters-6">DNS RCODEs</ulink>.
</para></listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Versioning</title>
<para>These D-Bus interfaces follow <ulink url="http://0pointer.de/blog/projects/versioning-dbus.html">
the usual interface versioning guidelines</ulink>.</para>
</refsect1>
</refentry>

1
man/rules/meson.build
View File

@ -49,6 +49,7 @@ manpages = [
['org.freedesktop.locale1', '5', [], 'ENABLE_LOCALED'],
['org.freedesktop.login1', '5', [], 'ENABLE_LOGIND'],
['org.freedesktop.machine1', '5', [], 'ENABLE_MACHINED'],
['org.freedesktop.resolve1', '5', [], 'ENABLE_RESOLVE'],
['org.freedesktop.timedate1', '5', [], 'ENABLE_TIMEDATED'],
['os-release', '5', [], ''],
['pam_systemd', '8', [], 'HAVE_PAM'],

11
man/systemd-resolved.service.xml
View File

@ -34,11 +34,12 @@
resolver and responder. Local applications may submit network name resolution requests via three interfaces:</para>
<itemizedlist>
<listitem><para>The native, fully-featured API <command>systemd-resolved</command> exposes on the bus. See the
<ulink url="https://www.freedesktop.org/wiki/Software/systemd/resolved">API Documentation</ulink> for
details. Usage of this API is generally recommended to clients as it is asynchronous and fully featured (for
example, properly returns DNSSEC validation status and interface scope for addresses as necessary for supporting
link-local networking).</para></listitem>
<listitem><para>The native, fully-featured API <command>systemd-resolved</command> exposes on the bus,
see
<citerefentry><refentrytitle>org.freedesktop.resolve1</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for details. Usage of this API is generally recommended to clients as it is asynchronous and fully
featured (for example, properly returns DNSSEC validation status and interface scope for addresses as
necessary for supporting link-local networking).</para></listitem>
<listitem><para>The glibc
<citerefentry project='man-pages'><refentrytitle>getaddrinfo</refentrytitle><manvolnum>3</manvolnum></citerefentry> API as defined