-<?xml version="1.0" standalone="no"?>
+<?xml version="1.0" standalone="no" ?>
<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"
[
<article id="index">
<articleinfo>
<title>D-Bus Specification</title>
- <releaseinfo>Version 0.11</releaseinfo>
- <date>6 February 2005</date>
+ <releaseinfo>Version 0.14</releaseinfo>
+ <date>May 12, 2010</date>
<authorgroup>
<author>
<firstname>Havoc</firstname>
</itemizedlist>
D-Bus is not intended to be a generic IPC system for any possible
application, and intentionally omits many features found in other
- IPC systems for this reason. D-Bus may turn out to be useful
- in unanticipated applications, but future versions of this
- spec and the reference implementation probably will not
+ IPC systems for this reason.
+ </para>
+
+ <para>
+ At the same time, the bus daemons offer a number of features not found in
+ other IPC systems, such as single-owner "bus names" (similar to X
+ selections), on-demand startup of services, and security policies.
+ In many ways, these features are the primary motivation for developing
+ D-Bus; other systems would have sufficed if IPC were the only goal.
+ </para>
+
+ <para>
+ D-Bus may turn out to be useful in unanticipated applications, but future
+ versions of this spec and the reference implementation probably will not
incorporate features that interfere with the core use cases.
</para>
document could use a serious audit to be sure it makes sense to do
so. Also, they are not capitalized.
</para>
+
+ <sect2 id="stability">
+ <title>Protocol and Specification Stability</title>
+ <para>
+ The D-Bus protocol is frozen (only compatible extensions are allowed) as
+ of November 8, 2006. However, this specification could still use a fair
+ bit of work to make interoperable reimplementation possible without
+ reference to the D-Bus reference implementation. Thus, this
+ specification is not marked 1.0. To mark it 1.0, we'd like to see
+ someone invest significant effort in clarifying the specification
+ language, and growing the specification to cover more aspects of the
+ reference implementation's behavior.
+ </para>
+ <para>
+ Until this work is complete, any attempt to reimplement D-Bus will
+ probably require looking at the reference implementation and/or asking
+ questions on the D-Bus mailing list about intended behavior.
+ Questions on the list are very welcome.
+ </para>
+ <para>
+ Nonetheless, this document should be a useful starting point and is
+ to our knowledge accurate, though incomplete.
+ </para>
+ </sect2>
</sect1>
but is useful in code that implements the protocol. This type code
is specified to allow such code to interoperate in non-protocol contexts.
</para>
-
+
+ <para>
+ Empty structures are not allowed; there must be at least one
+ type code between the parentheses.
+ </para>
+
<para>
<literal>ARRAY</literal> has ASCII character 'a' as type code. The array type code must be
followed by a <firstterm>single complete type</firstterm>. The single
</row><row>
<entry><literal>STRING</literal></entry>
<entry>115 (ASCII 's')</entry>
- <entry>UTF-8 string (<emphasis>must</emphasis> be valid UTF-8). Must be nul terminated.</entry>
+ <entry>UTF-8 string (<emphasis>must</emphasis> be valid UTF-8). Must be nul terminated and contain no other nul bytes.</entry>
</row><row>
<entry><literal>OBJECT_PATH</literal></entry>
<entry>111 (ASCII 'o')</entry>
<entry><literal>DICT_ENTRY</literal></entry>
<entry>101 (ASCII 'e'), 123 (ASCII '{'), 125 (ASCII '}') </entry>
<entry>Entry in a dict or map (array of key-value pairs)</entry>
+ </row><row>
+ <entry><literal>UNIX_FD</literal></entry>
+ <entry>104 (ASCII 'h')</entry>
+ <entry>Unix file descriptor</entry>
</row>
</tbody>
</tgroup>
<entry><literal>STRING</literal></entry>
<entry>A <literal>UINT32</literal> indicating the string's
length in bytes excluding its terminating nul, followed by
- string data of the given length, followed by a terminating nul
+ non-nul string data of the given length, followed by a terminating nul
byte.
</entry>
<entry>
given in the signature.
Unlike a message signature, the variant signature
can contain only a single complete type.
- So "i" is OK, "ii" is not.
+ So "i", "ai" or "(ii)" is OK, but "ii" is not.
</entry>
<entry>
1 (alignment of the signature)
<entry>
8
</entry>
+ </row><row>
+ <entry><literal>UNIX_FD</literal></entry>
+ <entry>32-bit unsigned integer in the message's byte
+ order. The actual file descriptors need to be
+ transferred out-of-band via some platform specific
+ mechanism. On the wire, values of this type store the index to the
+ file descriptor in the array of file descriptors that
+ accompany the message.</entry>
+ <entry>4</entry>
</row>
</tbody>
</tgroup>
the major protocol version of the receiving application does not
match, the applications will not be able to communicate and the
D-Bus connection must be disconnected. The major protocol
- version for this version of the specification is 0.
- FIXME this field is stupid and pointless to put in
- every message.
+ version for this version of the specification is 1.
</entry>
</row>
<row>
<entry>2nd <literal>UINT32</literal></entry>
<entry>The serial of this message, used as a cookie
by the sender to identify the reply corresponding
- to this request.
+ to this request. This must not be zero.
</entry>
</row>
<row>
<entry>1</entry>
<entry><literal>OBJECT_PATH</literal></entry>
<entry><literal>METHOD_CALL</literal>, <literal>SIGNAL</literal></entry>
- <entry>The object to send a call to,
+ <entry>The object to send a call to,
or the object a signal is emitted from.
+ The special path
+ <literal>/org/freedesktop/DBus/Local</literal> is reserved;
+ implementations should not send messages with this path,
+ and the reference implementation of the bus daemon will
+ disconnect any application that attempts to do so.
</entry>
</row>
<row>
The interface to invoke a method call on, or
that a signal is emitted from. Optional for
method calls, required for signals.
+ The special interface
+ <literal>org.freedesktop.DBus.Local</literal> is reserved;
+ implementations should not send messages with this
+ interface, and the reference implementation of the bus
+ daemon will disconnect any application that attempts to
+ do so.
</entry>
</row>
<row>
If omitted, it is assumed to be the
empty signature "" (i.e. the body must be 0-length).</entry>
</row>
+ <row>
+ <entry><literal>UNIX_FDS</literal></entry>
+ <entry>9</entry>
+ <entry><literal>UINT32</literal></entry>
+ <entry>optional</entry>
+ <entry>The number of Unix file descriptors that
+ accompany the message. If omitted, it is assumed
+ that no Unix file descriptors accompany the
+ message. The actual file descriptors need to be
+ transferred via platform specific mechanism
+ out-of-band. They must be sent at the same time as
+ part of the message itself. They may not be sent
+ before the first byte of the message itself is
+ transferred or after the last byte of the message
+ itself.</entry>
+ </row>
</tbody>
</tgroup>
</informaltable>
A signal emission is simply a single message of type <literal>SIGNAL</literal>.
It must have three header fields: <literal>PATH</literal> giving the object
the signal was emitted from, plus <literal>INTERFACE</literal> and <literal>MEMBER</literal> giving
- the fully-qualified name of the signal.
+ the fully-qualified name of the signal. The <literal>INTERFACE</literal> header is required
+ for signals, though it is optional for method calls.
</para>
</sect3>
<listitem><para>BEGIN</para></listitem>
<listitem><para>DATA <data in hex encoding></para></listitem>
<listitem><para>ERROR [human-readable error explanation]</para></listitem>
+ <listitem><para>NEGOTIATE_UNIX_FD</para></listitem>
</itemizedlist>
From server to client are as follows:
<listitem><para>OK <GUID in hex></para></listitem>
<listitem><para>DATA <data in hex encoding></para></listitem>
<listitem><para>ERROR</para></listitem>
+ <listitem><para>AGREE_UNIX_FD</para></listitem>
</itemizedlist>
</para>
<para>
an OK command must be sent to the client.
</para>
<para>
- The first octet received by the client after the \r\n of the OK
- command must be the first octet of the authenticated/encrypted
- stream of D-Bus messages.
- </para>
- <para>
The first octet received by the server after the \r\n of the BEGIN
command from the client must be the first octet of the
authenticated/encrypted stream of D-Bus messages.
</para>
+ <para>
+ If BEGIN is received by the server, the first octet received
+ by the client after the \r\n of the OK command must be the
+ first octet of the authenticated/encrypted stream of D-Bus
+ messages.
+ </para>
</sect2>
<sect2 id="auth-command-cancel">
<title>CANCEL Command</title>
<sect2 id="auth-command-ok">
<title>OK Command</title>
<para>
- The OK command indicates that the client has been authenticated,
- and that further communication will be a stream of D-Bus messages
- (optionally encrypted, as negotiated) rather than this protocol.
+ The OK command indicates that the client has been
+ authenticated. The client may now proceed with negotiating
+ Unix file descriptor passing. To do that it shall send
+ NEGOTIATE_UNIX_FD to the server.
</para>
<para>
- The first octet received by the client after the \r\n of the OK
- command must be the first octet of the authenticated/encrypted
- stream of D-Bus messages.
+ Otherwise, the client must respond to the OK command by
+ sending a BEGIN command, followed by its stream of messages,
+ or by disconnecting. The server must not accept additional
+ commands using this protocol after the BEGIN command has been
+ received. Further communication will be a stream of D-Bus
+ messages (optionally encrypted, as negotiated) rather than
+ this protocol.
</para>
<para>
- The client must respond to the OK command by sending a BEGIN
- command, followed by its stream of messages, or by disconnecting.
- The server must not accept additional commands using this protocol
- after the OK command has been sent.
+ If a client sends BEGIN the first octet received by the client
+ after the \r\n of the OK command must be the first octet of
+ the authenticated/encrypted stream of D-Bus messages.
</para>
<para>
The OK command has one argument, which is the GUID of the server.
negotiate extensions or changes to the D-Bus protocol in the future.
</para>
</sect2>
+ <sect2 id="auth-command-negotiate-unix-fd">
+ <title>NEGOTIATE_UNIX_FD Command</title>
+ <para>
+ The NEGOTIATE_UNIX_FD command indicates that the client
+ supports Unix file descriptor passing. This command may only
+ be sent after the connection is authenticated, i.e. after OK
+ was received by the client. This command may only be sent on
+ transports that support Unix file descriptor passing.
+ </para>
+ <para>
+ On receiving NEGOTIATE_UNIX_FD the server must respond with
+ either AGREE_UNIX_FD or ERROR. It shall respond the former if
+ the transport chosen supports Unix file descriptor passing and
+ the server supports this feature. It shall respond the latter
+ if the transport does not support Unix file descriptor
+ passing, the server does not support this feature, or the
+ server decides not to enable file descriptor passing due to
+ security or other reasons.
+ </para>
+ </sect2>
+ <sect2 id="auth-command-agree-unix-fd">
+ <title>AGREE_UNIX_FD Command</title>
+ <para>
+ The AGREE_UNIX_FD command indicates that the server supports
+ Unix file descriptor passing. This command may only be sent
+ after the connection is authenticated, and the client sent
+ NEGOTIATE_UNIX_FD to enable Unix file descriptor passing. This
+ command may only be sent on transports that support Unix file
+ descriptor passing.
+ </para>
+ <para>
+ On receiving AGREE_UNIX_FD the client must respond with BEGIN,
+ followed by its stream of messages, or by disconnecting. The
+ server must not accept additional commands using this protocol
+ after the BEGIN command has been received. Further
+ communication will be a stream of D-Bus messages (optionally
+ encrypted, as negotiated) rather than this protocol.
+ </para>
+ </sect2>
+ <sect2 id="auth-command-future">
+ <title>Future Extensions</title>
+ <para>
+ Future extensions to the authentication and negotiation
+ protocol are possible. For that new commands may be
+ introduced. If a client or server receives an unknown command
+ it shall respond with ERROR and not consider this fatal. New
+ commands may be introduced both before, and after
+ authentication, i.e. both before and after the OK command.
+ </para>
+ </sect2>
<sect2 id="auth-examples">
<title>Authentication examples</title>
C: BEGIN
</programlisting>
</figure>
+ <figure>
+ <title>Example of successful magic cookie authentication with successful negotiation of Unix FD passing</title>
+ <programlisting>
+ (MAGIC_COOKIE is a made up mechanism)
+
+ C: AUTH MAGIC_COOKIE 3138363935333137393635383634
+ S: OK 1234deadbeef
+ C: NEGOTIATE_UNIX_FD
+ S: AGREE_UNIX_FD
+ C: BEGIN
+ </programlisting>
+ </figure>
+ <figure>
+ <title>Example of successful magic cookie authentication with unsuccessful negotiation of Unix FD passing</title>
+ <programlisting>
+ (MAGIC_COOKIE is a made up mechanism)
+
+ C: AUTH MAGIC_COOKIE 3138363935333137393635383634
+ S: OK 1234deadbeef
+ C: NEGOTIATE_UNIX_FD
+ S: ERROR
+ C: BEGIN
+ </programlisting>
+ </figure>
</para>
</sect2>
<sect2 id="auth-states">
directory.
</para>
<para>
+ Throughout this description, "hex encoding" must output the digits
+ from a to f in lower-case; the digits A to F must not be used
+ in the DBUS_COOKIE_SHA1 mechanism.
+ </para>
+ <para>
Authentication proceeds as follows:
<itemizedlist>
<listitem>
<para>
The client sends the username it would like to authenticate
- as.
+ as, hex-encoded.
</para>
</listitem>
<listitem>
The server sends the name of its "cookie context" (see below); a
space character; the integer ID of the secret cookie the client
must demonstrate knowledge of; a space character; then a
- hex-encoded randomly-generated challenge string.
+ randomly-generated challenge string, all of this hex-encoded into
+ one, single string.
</para>
</listitem>
<listitem>
<para>
- The client locates the cookie, and generates its own hex-encoded
- randomly-generated challenge string. The client then
- concatenates the server's hex-encoded challenge, a ":"
- character, its own hex-encoded challenge, another ":" character,
- and the hex-encoded cookie. It computes the SHA-1 hash of this
- composite string. It sends back to the server the client's
- hex-encoded challenge string, a space character, and the SHA-1
- hash.
+ The client locates the cookie and generates its own
+ randomly-generated challenge string. The client then concatenates
+ the server's decoded challenge, a ":" character, its own challenge,
+ another ":" character, and the cookie. It computes the SHA-1 hash
+ of this composite string as a hex digest. It concatenates the
+ client's challenge string, a space character, and the SHA-1 hex
+ digest, hex-encodes the result and sends it back to the server.
</para>
</listitem>
<listitem>
<para>
A server may specify a key-value pair with the key <literal>guid</literal>
- and the value a hex-encoded 16-byte sequence. This globally unique ID must
- be created by filling the first 4 bytes with a 32-bit UNIX time since the
- epoch, and the remaining 12 bytes with random bytes. If present, the GUID
- may be used to distinguish one server from another. A server should use a
- different GUID for each address it listens on. For example, if a message
- bus daemon offers both UNIX domain socket and TCP connections, but treats
- clients the same regardless of how they connect, those two connections are
- equivalent post-connection but should have distinct GUIDs to distinguish
- the kinds of connection.
+ and the value a hex-encoded 16-byte sequence. <xref linkend="uuids"/>
+ describes the format of the <literal>guid</literal> field. If present,
+ this UUID may be used to distinguish one server address from another. A
+ server should use a different UUID for each address it listens on. For
+ example, if a message bus daemon offers both UNIX domain socket and TCP
+ connections, but treats clients the same regardless of how they connect,
+ those two connections are equivalent post-connection but should have
+ distinct UUIDs to distinguish the kinds of connection.
</para>
<para>
- The intent of the GUID feature is to allow a client to avoid opening
- multiple identical connections to the same server, by allowing the client
- to check whether an address corresponds to an already-existing connection.
- Comparing two addresses is insufficient, because addresses can be recycled
- by distinct servers.
+ The intent of the address UUID feature is to allow a client to avoid
+ opening multiple identical connections to the same server, by allowing the
+ client to check whether an address corresponds to an already-existing
+ connection. Comparing two addresses is insufficient, because addresses
+ can be recycled by distinct servers, and equivalent addresses may look
+ different if simply compared as strings (for example, the host in a TCP
+ address can be given as an IP address or as a hostname).
+ </para>
+
+ <para>
+ Note that the address key is <literal>guid</literal> even though the
+ rest of the API and documentation says "UUID," for historical reasons.
</para>
<para>
length path name. Names which were shorter than the fixed length
would be padded by Nul bytes.
</para>
+ <para>
+ Unix domain sockets are not available on windows.
+ </para>
+ <sect3 id="transports-unix-domain-sockets-addresses">
+ <title>Server Address Format</title>
+ <para>
+ Unix domain socket addresses are identified by the "unix:" prefix
+ and support the following key/value pairs:
+ </para>
+ <informaltable>
+ <tgroup cols="3">
+ <thead>
+ <row>
+ <entry>Name</entry>
+ <entry>Values</entry>
+ <entry>Description</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>path</entry>
+ <entry>(path)</entry>
+ <entry>path of the unix domain socket. If set, the "tmpdir" and "abstract" key must not be set.</entry>
+ </row>
+ <row>
+ <entry>tmpdir</entry>
+ <entry>(path)</entry>
+ <entry>temporary directory in which a socket file with a random file name starting with 'dbus-' will be created by the server. This key can only be used in server addresses, not in client addresses. If set, the "path" and "abstract" key must not be set.</entry>
+ </row>
+ <row>
+ <entry>abstract</entry>
+ <entry>(string)</entry>
+ <entry>unique string (path) in the abstract namespace. If set, the "path" or "tempdir" key must not be set.</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </informaltable>
+ </sect3>
+ </sect2>
+ <sect2 id="transports-tcp-sockets">
+ <title>TCP Sockets</title>
+ <para>
+ The tcp transport provides TCP/IP based connections between clients
+ located on the same or different hosts.
+ </para>
+ <para>
+ Using tcp transport without any additional secure authentification mechanismus
+ over a network is unsecure.
+ </para>
+ <para>
+ Windows notes: Because of the tcp stack on windows does not provide sending
+ credentials over a tcp connection, the EXTERNAL authentification
+ mechanismus does not work.
+ </para>
+ <sect3 id="transports-tcp-sockets-addresses">
+ <title>Server Address Format</title>
+ <para>
+ TCP/IP socket addresses are identified by the "tcp:" prefix
+ and support the following key/value pairs:
+ </para>
+ <informaltable>
+ <tgroup cols="3">
+ <thead>
+ <row>
+ <entry>Name</entry>
+ <entry>Values</entry>
+ <entry>Description</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>host</entry>
+ <entry>(string)</entry>
+ <entry>dns name or ip address</entry>
+ </row>
+ <row>
+ <entry>port</entry>
+ <entry>(number)</entry>
+ <entry>The tcp port the server will open. A zero value let the server
+ choose a free port provided from the underlaying operating system.
+ libdbus is able to retrieve the real used port from the server.
+ </entry>
+ </row>
+ <row>
+ <entry>family</entry>
+ <entry>(string)</entry>
+ <entry>If set, provide the type of socket family either "ipv4" or "ipv6". If unset, the family is unspecified.</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </informaltable>
+ </sect3>
+ </sect2>
+ <sect2 id="transports-nonce-tcp-sockets">
+ <title>Nonce-secured TCP Sockets</title>
+ <para>
+ The nonce-tcp transport provides a secured TCP transport, using a
+ simple authentication mechanism to ensure that only clients with read
+ access to a certain location in the filesystem can connect to the server.
+ The server writes a secret, the nonce, to a file and an incoming client
+ connection is only accepted if the client sends the nonce right after
+ the connect. The nonce mechanism requires no setup and is orthogonal to
+ the higher-level authentication mechanisms described in the
+ Authentication section.
+ </para>
+
+ <para>
+ On start, the server generates a random 16 byte nonce and writes it
+ to a file in the user's temporary directory. The nonce file location
+ is published as part of the server's D-Bus address using the
+ "noncefile" key-value pair.
+
+ After an accept, the server reads 16 bytes from the socket. If the
+ read bytes do not match the nonce stored in the nonce file, the
+ server MUST immediately drop the connection.
+ If the nonce match the received byte sequence, the client is accepted
+ and the transport behaves like an unsecured tcp transport.
+ </para>
+ <para>
+ After a successful connect to the server socket, the client MUST read
+ the nonce from the file published by the server via the noncefile=
+ key-value pair and send it over the socket. After that, the
+ transport behaves like an unsecured tcp transport.
+ </para>
+ <sect3 id="transports-nonce-tcp-sockets-addresses">
+ <title>Server Address Format</title>
+ <para>
+ Nonce TCP/IP socket addresses uses the "nonce-tcp:" prefix
+ and support the following key/value pairs:
+ </para>
+ <informaltable>
+ <tgroup cols="3">
+ <thead>
+ <row>
+ <entry>Name</entry>
+ <entry>Values</entry>
+ <entry>Description</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>host</entry>
+ <entry>(string)</entry>
+ <entry>dns name or ip address</entry>
+ </row>
+ <row>
+ <entry>port</entry>
+ <entry>(number)</entry>
+ <entry>The tcp port the server will open. A zero value let the server
+ choose a free port provided from the underlaying operating system.
+ libdbus is able to retrieve the real used port from the server.
+ </entry>
+ </row>
+ <row>
+ <entry>family</entry>
+ <entry>(string)</entry>
+ <entry>If set, provide the type of socket family either "ipv4" or "ipv6". If unset, the family is unspecified.</entry>
+ </row>
+ <row>
+ <entry>noncefile</entry>
+ <entry>(path)</entry>
+ <entry>file location containing the secret</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </informaltable>
+ </sect3>
</sect2>
+
</sect1>
<sect1 id="naming-conventions">
hyphens.
</para>
</sect1>
+
+ <sect1 id="uuids">
+ <title>UUIDs</title>
+ <para>
+ A working D-Bus implementation uses universally-unique IDs in two places.
+ First, each server address has a UUID identifying the address,
+ as described in <xref linkend="addresses"/>. Second, each operating
+ system kernel instance running a D-Bus client or server has a UUID
+ identifying that kernel, retrieved by invoking the method
+ org.freedesktop.DBus.Peer.GetMachineId() (see <xref
+ linkend="standard-interfaces-peer"/>).
+ </para>
+ <para>
+ The term "UUID" in this document is intended literally, i.e. an
+ identifier that is universally unique. It is not intended to refer to
+ RFC4122, and in fact the D-Bus UUID is not compatible with that RFC.
+ </para>
+ <para>
+ The UUID must contain 128 bits of data and be hex-encoded. The
+ hex-encoded string may not contain hyphens or other non-hex-digit
+ characters, and it must be exactly 32 characters long. To generate a
+ UUID, the current reference implementation concatenates 96 bits of random
+ data followed by the 32-bit time in seconds since the UNIX epoch (in big
+ endian byte order).
+ </para>
+ <para>
+ It would also be acceptable and probably better to simply generate 128
+ bits of random data, as long as the random number generator is of high
+ quality. The timestamp could conceivably help if the random bits are not
+ very random. With a quality random number generator, collisions are
+ extremely unlikely even with only 96 bits, so it's somewhat academic.
+ </para>
+ <para>
+ Implementations should, however, stick to random data for the first 96 bits
+ of the UUID.
+ </para>
+ </sect1>
<sect1 id="standard-interfaces">
<title>Standard Interfaces</title>
<title><literal>org.freedesktop.DBus.Peer</literal></title>
<para>
The <literal>org.freedesktop.DBus.Peer</literal> interface
- has one method:
+ has two methods:
<programlisting>
org.freedesktop.DBus.Peer.Ping ()
+ org.freedesktop.DBus.Peer.GetMachineId (out STRING machine_uuid)
</programlisting>
</para>
<para>
<literal>org.freedesktop.DBus.Peer.Ping</literal>, an application should do
nothing other than reply with a <literal>METHOD_RETURN</literal> as
usual. It does not matter which object path a ping is sent to. The
- reference implementation should simply handle this method on behalf of
- all objects, though it doesn't yet. (The point is, you're really pinging
- the peer process, not a specific object.)
+ reference implementation handles this method automatically.
+ </para>
+ <para>
+ On receipt of the <literal>METHOD_CALL</literal> message
+ <literal>org.freedesktop.DBus.Peer.GetMachineId</literal>, an application should
+ reply with a <literal>METHOD_RETURN</literal> containing a hex-encoded
+ UUID representing the identity of the machine the process is running on.
+ This UUID must be the same for all processes on a single system at least
+ until that system next reboots. It should be the same across reboots
+ if possible, but this is not always possible to implement and is not
+ guaranteed.
+ It does not matter which object path a GetMachineId is sent to. The
+ reference implementation handles this method automatically.
+ </para>
+ <para>
+ The UUID is intended to be per-instance-of-the-operating-system, so may represent
+ a virtual machine running on a hypervisor, rather than a physical machine.
+ Basically if two processes see the same UUID, they should also see the same
+ shared memory, UNIX domain sockets, process IDs, and other features that require
+ a running OS kernel in common between the processes.
+ </para>
+ <para>
+ The UUID is often used where other programs might use a hostname. Hostnames
+ can change without rebooting, however, or just be "localhost" - so the UUID
+ is more robust.
+ </para>
+ <para>
+ <xref linkend="uuids"/> explains the format of the UUID.
</para>
</sect2>
org.freedesktop.DBus.Properties.Set (in STRING interface_name,
in STRING property_name,
in VARIANT value);
+ org.freedesktop.DBus.Properties.GetAll (in STRING interface_name,
+ out DICT<STRING,VARIANT> props);
</programlisting>
</para>
<para>
deterministic rule, or returning an error, are the reasonable
possibilities).
</para>
+ <para>
+ If one or more properties change on an object, the
+ <literal>org.freedesktop.DBus.Properties.PropertiesChanged</literal>
+ signal may be emitted (this signal was added in 0.14):
+ </para>
+ <para>
+ <programlisting>
+ org.freedesktop.DBus.Properties.PropertiesChanged (STRING interface_name,
+ DICT<STRING,VARIANT> changed_properties,
+ ARRAY<STRING> invalidated_properties);
+ </programlisting>
+ </para>
+ <para>
+ where <literal>changed_properties</literal> is a dictionary
+ containing the changed properties with the new values and
+ <literal>invalidated_properties</literal> is an array of
+ properties that changed but the value is not conveyed.
+ </para>
+ <para>
+ Whether the <literal>PropertiesChanged</literal> signal is
+ supported can be determined by calling
+ <literal>org.freedesktop.DBus.Introspectable.Introspect</literal>. Note
+ that the signal may be supported for an object but it may
+ differ how whether and how it is used on a per-property basis
+ (for e.g. performance or security reasons). Each property (or
+ the parent interface) must be annotated with the
+ <literal>org.freedesktop.DBus.Property.EmitsChangedSignal</literal>
+ annotation to convey this (usually the default value
+ <literal>true</literal> is sufficient meaning that the
+ annotation does not need to be used). See <xref
+ linkend="introspection-format"/> for details on this
+ annotation.
+ </para>
</sect2>
</sect1>
<entry>true,false</entry>
<entry>If set, don't expect a reply to the method call; defaults to false.</entry>
</row>
+ <row>
+ <entry>org.freedesktop.DBus.Property.EmitsChangedSignal</entry>
+ <entry>true,invalidates,false</entry>
+ <entry>
+ <para>
+ If set to <literal>false</literal>, the
+ <literal>org.freedesktop.DBus.Properties.PropertiesChanged</literal>
+ signal, see <xref
+ linkend="standard-interfaces-properties"/> is not
+ guaranteed to be emitted if the property changes.
+ </para>
+ <para>
+ If set to <literal>invalidates</literal> the signal
+ is emitted but the value is not included in the
+ signal.
+ </para>
+ <para>
+ If set to <literal>true</literal> the signal is
+ emitted with the value included.
+ </para>
+ <para>
+ The value for the annotation defaults to
+ <literal>true</literal> if the enclosing interface
+ element does not specify the annotation. Otherwise it
+ defaults to the value specified in the enclosing
+ interface element.
+ </para>
+ </entry>
+ </row>
</tbody>
</tgroup>
</informaltable>
</tgroup>
</informaltable>
</para>
- </sect3>
+ </sect3>
+
+ <sect3 id="bus-messages-list-queued-owners">
+ <title><literal>org.freedesktop.DBus.ListQueuedOwners</literal></title>
+ <para>
+ As a method:
+ <programlisting>
+ ARRAY of STRING ListQueuedOwners (in STRING name)
+ </programlisting>
+ Message arguments:
+ <informaltable>
+ <tgroup cols="3">
+ <thead>
+ <row>
+ <entry>Argument</entry>
+ <entry>Type</entry>
+ <entry>Description</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>0</entry>
+ <entry>STRING</entry>
+ <entry>The well-known bus name to query, such as
+ <literal>com.example.cappuccino</literal></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </informaltable>
+ Reply arguments:
+ <informaltable>
+ <tgroup cols="3">
+ <thead>
+ <row>
+ <entry>Argument</entry>
+ <entry>Type</entry>
+ <entry>Description</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>0</entry>
+ <entry>ARRAY of STRING</entry>
+ <entry>The unique bus names of connections currently queued
+ for the name</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </informaltable>
+ </para>
+ <para>
+ This method call should be sent to
+ <literal>org.freedesktop.DBus</literal> and lists the connections
+ currently queued for a bus name (see
+ <xref linkend="term-queued-owner"/>).
+ </para>
+ </sect3>
</sect2>
<sect2 id="message-bus-routing">
</para>
<para>
Match rules are added using the AddMatch bus method
- (see xref linkend="bus-messages-add-match"/>). Rules are
+ (see <xref linkend="bus-messages-add-match"/>). Rules are
specified as a string of comma separated key/value pairs.
Excluding a key from the rule indicates a wildcard match.
For instance excluding the the member from a match rule but
<entry><literal>interface</literal></entry>
<entry>An interface name (see <xref linkend="message-protocol-names-interface"/>)</entry>
<entry>Match messages sent over or to a particular interface. An example of an
- interface match is interface='org.freedesktop.Hal.Manager'</entry>
+ interface match is interface='org.freedesktop.Hal.Manager'.
+ If a message omits the interface header, it must not match any rule
+ that specifies this key.</entry>
</row>
<row>
<entry><literal>member</literal></entry>
example of a destination match is destination=':1.0'</entry>
</row>
<row>
- <entry><literal>arg[1, 2, 3, ...]</literal></entry>
+ <entry><literal>arg[0, 1, 2, 3, ...]</literal></entry>
<entry>Any string</entry>
<entry>Arg matches are special and are used for further restricting the
match based on the arguments in the body of a message. As of this time
only string arguments can be matched. An example of an argument match
- would be arg3='Foo'.</entry>
+ would be arg3='Foo'. Only argument indexes from 0 to 63 should be
+ accepted.</entry>
+ </row>
+ <row>
+ <entry><literal>arg[0, 1, 2, 3, ...]path</literal></entry>
+ <entry>Any string</entry>
+ <entry>Argument path matches provide a specialised form of wildcard
+ matching for path-like namespaces. As with normal argument matches,
+ if the argument is exactly equal to the string given in the match
+ rule then the rule is satisfied. Additionally, there is also a
+ match when either the string given in the match rule or the
+ appropriate message argument ends with '/' and is a prefix of the
+ other. An example argument path match is arg0path='/aa/bb/'. This
+ would match messages with first arguments of '/', '/aa/',
+ '/aa/bb/', '/aa/bb/cc/' and '/aa/bb/cc'. It would not match
+ messages with first arguments of '/aa/b', '/aa' or even '/aa/bb'.</entry>
</row>
</tbody>
</tgroup>
</sect3>
+ <sect3 id="bus-messages-update-activation-environment">
+ <title><literal>org.freedesktop.DBus.UpdateActivationEnvironment</literal></title>
+ <para>
+ As a method:
+ <programlisting>
+ UpdateActivationEnvironment (in ARRAY of DICT<STRING,STRING> environment)
+ </programlisting>
+ Message arguments:
+ <informaltable>
+ <tgroup cols="3">
+ <thead>
+ <row>
+ <entry>Argument</entry>
+ <entry>Type</entry>
+ <entry>Description</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>0</entry>
+ <entry>ARRAY of DICT<STRING,STRING></entry>
+ <entry>Environment to add or update</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </informaltable>
+ Normally, session bus activated services inherit the environment of the bus daemon. This method adds to or modifies that environment when activating services.
+ </para>
+ <para>
+ Some bus instances, such as the standard system bus, may disable access to this method for some or all callers.
+ </para>
+ <para>
+ Note, both the environment variable names and values must be valid UTF-8. There's no way to update the activation environment with data that is invalid UTF-8.
+ </para>
+
+ </sect3>
+
<sect3 id="bus-messages-get-name-owner">
<title><literal>org.freedesktop.DBus.GetNameOwner</literal></title>
<para>
</para>
</sect3>
+ <sect3 id="bus-messages-get-connection-unix-process-id">
+ <title><literal>org.freedesktop.DBus.GetConnectionUnixProcessID</literal></title>
+ <para>
+ As a method:
+ <programlisting>
+ UINT32 GetConnectionUnixProcessID (in STRING bus_name)
+ </programlisting>
+ Message arguments:
+ <informaltable>
+ <tgroup cols="3">
+ <thead>
+ <row>
+ <entry>Argument</entry>
+ <entry>Type</entry>
+ <entry>Description</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>0</entry>
+ <entry>STRING</entry>
+ <entry>Unique or well-known bus name of the connection to
+ query, such as <literal>:12.34</literal> or
+ <literal>com.example.tea</literal></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </informaltable>
+ Reply arguments:
+ <informaltable>
+ <tgroup cols="3">
+ <thead>
+ <row>
+ <entry>Argument</entry>
+ <entry>Type</entry>
+ <entry>Description</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>0</entry>
+ <entry>UINT32</entry>
+ <entry>Unix process id</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </informaltable>
+ Returns the Unix process ID of the process connected to the server. If
+ unable to determine it (for instance, because the process is not on the
+ same machine as the bus daemon), an error is returned.
+ </para>
+ </sect3>
+
<sect3 id="bus-messages-add-match">
<title><literal>org.freedesktop.DBus.AddMatch</literal></title>
<para>
</para>
</sect3>
+ <sect3 id="bus-messages-get-id">
+ <title><literal>org.freedesktop.DBus.GetId</literal></title>
+ <para>
+ As a method:
+ <programlisting>
+ GetId (out STRING id)
+ </programlisting>
+ Reply arguments:
+ <informaltable>
+ <tgroup cols="3">
+ <thead>
+ <row>
+ <entry>Argument</entry>
+ <entry>Type</entry>
+ <entry>Description</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>0</entry>
+ <entry>STRING</entry>
+ <entry>Unique ID identifying the bus daemon</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </informaltable>
+ Gets the unique ID of the bus. The unique ID here is shared among all addresses the
+ bus daemon is listening on (TCP, UNIX domain socket, etc.) and its format is described in
+ <xref linkend="uuids"/>. Each address the bus is listening on also has its own unique
+ ID, as described in <xref linkend="addresses"/>. The per-bus and per-address IDs are not related.
+ There is also a per-machine ID, described in <xref linkend="standard-interfaces-peer"/> and returned
+ by org.freedesktop.DBus.Peer.GetMachineId().
+ For a desktop session bus, the bus ID can be used as a way to uniquely identify a user's session.
+ </para>
+ </sect3>
+
</sect2>
</sect1>
</glossary>
</article>
-
projects / platform / upstream / dbus.git / blobdiff