From e09a36bd4617dc6e4dfc447b62affba0d112a0e6 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= Date: Thu, 9 Apr 2020 15:42:27 +0200 Subject: [PATCH] man: import org.freedesktop.hostname1(3) from the wiki --- man/custom-entities.ent.in | 1 + man/org.freedesktop.hostname1.xml | 236 ++++++++++++++++++++++++++++++ man/rules/meson.build | 1 + man/systemd-hostnamed.service.xml | 34 +++-- 4 files changed, 263 insertions(+), 9 deletions(-) create mode 100644 man/org.freedesktop.hostname1.xml diff --git a/man/custom-entities.ent.in b/man/custom-entities.ent.in index 84a29f5de4..03fe05f1bc 100644 --- a/man/custom-entities.ent.in +++ b/man/custom-entities.ent.in @@ -6,6 +6,7 @@ + diff --git a/man/org.freedesktop.hostname1.xml b/man/org.freedesktop.hostname1.xml new file mode 100644 index 0000000000..a381cb8239 --- /dev/null +++ b/man/org.freedesktop.hostname1.xml @@ -0,0 +1,236 @@ + + + +%entities; +]> + + + + + org.freedesktop.hostname1 + systemd + + + + org.freedesktop.hostname1 + 5 + + + + org.freedesktop.hostname1 + The D-Bus interface of systemd-hostnamed + + + + Introduction + + + systemd-hostnamed.service8 + is a system service that can be used to control the host name and related machine meta data from user + programs. This page describes the hostname semantics and the D-Bus interface. + + + + The D-Bus API + + The service exposes the following interfaces on the bus: + + +$ gdbus introspect --system \ + --dest org.freedesktop.hostname1 \ + --object-path /org/freedesktop/hostname1 + +node /org/freedesktop/hostname1 { + interface org.freedesktop.hostname1 { + methods: + SetHostname(in s name, + in b user_interaction); + SetStaticHostname(in s name, + in b user_interaction); + SetPrettyHostname(in s name, + in b user_interaction); + SetIconName(in s name, + in b user_interaction); + SetChassis(in s name, + in b user_interaction); + signals: + properties: + readonly s Hostname = 'dhcp-192-168-47-11'; + readonly s StaticHostname = 'lennarts-computer'; + readonly s PrettyHostname = 'Lennart’s Computer'; + readonly s IconName = 'computer-laptop'; + readonly s Chassis = 'laptop'; + }; + interface org.freedesktop.DBus.Properties { + }; + interface org.freedesktop.DBus.Introspectable { + }; + interface org.freedesktop.DBus.Peer { + }; +}; + + + Whenever the hostname or other meta data is changed via the daemon, + PropertyChanged signals are sent out to subscribed clients. Changing a hostname + using this interface is authenticated via PolicyKit. + + + + Semantics + + The static (configured) host name is the one configured in + /etc/hostname. It is chosen by the local user. It is not always in sync with the + current hostname as returned by the + gethostname3 + system call. If no host name is configured this property will be the empty string. Setting this property + to the empty string will remove /etc/hostname. This hostname should be an + internet-style hostname, 7-bit lowercase ASCII, no special chars/spaces. + + The transient (dynamic) host name is the one configured via the kernel's + sethostname3. + It can be different from the static hostname in case DHCP or mDNS have been configured to change the name + based on network information. + This property is never empty. If no hostname is set this will default to + &FALLBACK_HOSTNAME; (configurable at compilation time). Setting this property to the + empty string will reset the dynamic hostname to the static host name. If no static host name is + configured the dynamic host name will be reset to &FALLBACK_HOSTNAME;. This hostname + should be an internet-style hostname, 7-bit lowercase ASCII, no special chars/spaces. + + The pretty host name is a free-form UTF-8 host name for presentation to the + user. User interfaces should ensure that the pretty hostname and the static hostname stay in sync. + I.e. when the former is Lennart’s Computer the latter should be + lennarts-computer. If no pretty host name is set this setting will be the empty + string. Applications should then find a suitable fallback, such as the dynamic hostname. + + The icon name is a name following the XDG icon naming spec. If not set, + information such as the chassis type (see below) is used to find a suitable fallback icon name + (i.e. computer-laptop vs. computer-desktop is picked based on the + chassis information). If no such data is available, returns the empty string. In that case an application + should fall back to a replacement icon, for example computer. If this property is set + to the empty string, this automatic fallback name selection is enabled again. + + The chassis type should be one of the following that are currently defined: + desktop, laptop, server, + tablet, handset, as well as the special chassis types + vm and container for virtualized systems. Note that in most cases + the chassis type will be determined automatically from DMI/SMBIOS/ACPI firmware information. Writing to + this setting is hence useful only to override misdetected chassis types, or configure a chassis type if + none could be auto-detected. Set this property to the empty string to reenable the automatic detection of + the chassis type from firmware information. + + A client which wants to change the local host name for DHCP/mDNS should invoke + SetHostname("newname", false) as soon as the name is available and afterwards reset it via + SetHostname(""). + + Note that systemd-hostnamed starts only on request and terminates after a + short idle period. This effectively means that PropertyChanged messages are not sent + out for changes made directly on the files (as in: administrator edits the files with vi). This is + actually intended behavior: manual configuration changes should require manual reloading of them. + + The transient (dynamic) hostname directly maps to the kernel hostname. This hostname should be + assumed to be highly dynamic, and hence should be watched directly, without involving + PropertyChanged messages from systemd-hostnamed. For that, open + /proc/sys/kernel/hostname and + poll3 + for SIGHUP which is triggered by the kernel every time the hostname changes. Again: + this is special for the transient (dynamic) hostname, and does not apply to the configured (fixed) + hostname. + + Applications may bypass the daemon to read the hostname data if notifications of host name changes + are not necessary. Use + gethostname3, + /etc/hostname (possibly with per-distribution fallbacks), and + machine-info3 + for that. For more information on these files and syscalls see the respective man pages. + + The user_interaction boolean parameters can be used to control whether PolicyKit should + interactively ask the user for authentication credentials if it needs to. + + The PolicyKit action for SetHostname() is + org.freedesktop.hostname1.set-hostname. For + SetStaticHostname() and SetPrettyHostname() it is + org.freedesktop.hostname1.set-static-hostname. For + SetIconName() and SetChassis() it is + org.freedesktop.hostname1.set-machine-info. + + Here are three examples how the pretty hostname and the icon name should be used: + + When registering DNS-SD services: use the pretty host name in the service name, and + pass the icon name in the TXT data, if there is an icon name. Browsing clients can then show the server + icon on each service. Especially useful for WebDAV stuff. Similar for UPnP media + sharing. + + Set the bluetooth name to the pretty host name. + + When your file browser has a "Computer" icon, replace the name with the pretty hostname if set, and the icon with the icon name, if it is set. + + + To properly handle name lookups with changing local hostnames without having to edit + /etc/hosts for them, we recommend using systemd-hostnamed in + combination with nss-myhostname3. + + + Here are some recommendations to follow when generating a static (internet) hostname from a pretty + name: + + Generate a single DNS label only, not an FQDN. That means no dots allowed. Strip them, + or replace them by -. + + It's probably safer not to use any non-ASCII chars, even if DNS allows this in some way + these days. In fact, restrict your charset to a-zA-Z0-9 and -. + Strip other chars, or try to replace them in some smart way with chars from this set, for example + ä → ae, and use - as replacement for all kinds + of punctuation chars or spaces. + + Try to avoid creating repeated -, as well as - as + the first or last char. + + Limit the hostname to 63 chars, which is the length of a DNS label. + + If after stripping special chars the empty string is the result, you can pass this + as-is to systemd-hostnamed in which case it will automatically make + &FALLBACK_HOSTNAME; out of this. + + It probably is a good idea to replace uppercase by lowercase chars. + + + Note that while systemd-hostnamed applies some checks to the hostname you pass + they are much looser than the recommendations above. For example, systemd-hostnamed + will also accept _ in the hostname, but I'd recommend not using this to avoid clashes + with DNS-SD service types. Also systemd-hostnamed allows longer hostnames, but + because of the DNS label limitations, I'd recommend not making use of this. + + Here are a couple of example conversions: + + Lennart's PC → lennarts-pc + Müllers Computer → muellers-computer + Voran! → voran + Es war einmal ein Männlein → es-war-einmal-ein-maennlein + Jawoll. Ist doch wahr! → jawoll-ist-doch-wahr + レナート → localhost + ...zack!!! zack!... → zack-zack + + + Oh, and of course, an already valid internet hostname label you enter and pass through this + conversion should stay unmodified, so that users have direct control of it, if they want -- by simply + ignoring the fact that the pretty hostname is pretty and just edit it as if it was the normal internet + name. + + + + Versioning + + These D-Bus interfaces follow + the usual interface versioning guidelines. + + + + See also + + David Zeuthen's original Fedora + Feature page about xdg-hostname + + diff --git a/man/rules/meson.build b/man/rules/meson.build index 6beed3f6dd..d69286301b 100644 --- a/man/rules/meson.build +++ b/man/rules/meson.build @@ -44,6 +44,7 @@ manpages = [ ['nss-mymachines', '8', ['libnss_mymachines.so.2'], 'ENABLE_NSS_MYMACHINES'], ['nss-resolve', '8', ['libnss_resolve.so.2'], 'ENABLE_NSS_RESOLVE'], ['nss-systemd', '8', ['libnss_systemd.so.2'], 'ENABLE_NSS_SYSTEMD'], + ['org.freedesktop.hostname1', '5', [], 'ENABLE_HOSTNAMED'], ['org.freedesktop.import1', '5', [], 'ENABLE_IMPORTD'], ['org.freedesktop.login1', '5', [], 'ENABLE_LOGIND'], ['org.freedesktop.machine1', '5', [], 'ENABLE_MACHINED'], diff --git a/man/systemd-hostnamed.service.xml b/man/systemd-hostnamed.service.xml index 19bd4c06f2..185e038809 100644 --- a/man/systemd-hostnamed.service.xml +++ b/man/systemd-hostnamed.service.xml @@ -18,7 +18,7 @@ systemd-hostnamed.service systemd-hostnamed - Host name bus mechanism + Daemon to control system hostname from programs @@ -29,19 +29,35 @@ Description - systemd-hostnamed is a system service - that may be used as a mechanism to change the system's hostname. - systemd-hostnamed is automatically activated - on request and terminates itself when it is unused. + systemd-hostnamed.service is a system service that may be used to change the + system's hostname and related machine meta data from user programs. It is automatically activated on + request and terminates itself when unused. + + It currently offers access to five variables: + + The current host name (Example: dhcp-192-168-47-11) + + + The static (configured) host name (Example: + lennarts-computer) + + The pretty host name (Example: Lennart's Computer) + + + A suitable icon name for the local host (Example: + computer-laptop) + + A chassis type (Example: tablet) + + The tool hostnamectl1 is a command line client to this service. - See the - developer documentation for information about the APIs - systemd-hostnamed provides. + See the + org.freedesktop.hostname11 + for a description of the D-Bus API.