1207 lines
40 KiB
XML
1207 lines
40 KiB
XML
<?xml version="1.0" encoding="UTF-8" ?>
|
||
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.3//EN"
|
||
"http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd">
|
||
|
||
<!-- lifted from troff+ms+XMan by doclifter -->
|
||
<book id="xtrans">
|
||
|
||
<bookinfo>
|
||
<title>X Transport Interface</title>
|
||
<subtitle>X Consortium Standard</subtitle>
|
||
<releaseinfo>X Version 11, Release 7.X</releaseinfo>
|
||
<authorgroup>
|
||
<author>
|
||
<firstname>Stuart</firstname><surname>Anderson</surname>
|
||
</author>
|
||
</authorgroup>
|
||
<othercredit><firstname>Ralph</firstname><surname>Mor</surname></othercredit>
|
||
<othercredit><firstname>Alan</firstname><surname>Coopersmith</surname></othercredit>
|
||
<corpname>NCR Corporation</corpname>
|
||
<releaseinfo>Version 0.7</releaseinfo>
|
||
<affiliation><orgname>The Open Group</orgname></affiliation>
|
||
<productnumber>X Version 11, Release 7.x</productnumber>
|
||
|
||
<legalnotice>
|
||
<para>
|
||
Copyright © 1993, 1994 NCR Corporation - Dayton, Ohio, USA
|
||
</para>
|
||
|
||
<para>
|
||
All Rights Reserved
|
||
</para>
|
||
|
||
<para>
|
||
Permission to use, copy, modify, and distribute this software and its
|
||
documentation for any purpose and without fee is hereby granted, provided
|
||
that the above copyright notice appear in all copies and that both that
|
||
copyright notice and this permission notice appear in supporting
|
||
documentation, and that the name NCR not be used in advertising
|
||
or publicity pertaining to distribution of the software without specific,
|
||
written prior permission. NCR makes no representations about the
|
||
suitability of this software for any purpose. It is provided "as is"
|
||
without express or implied warranty.
|
||
</para>
|
||
|
||
<para>
|
||
NCR DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
|
||
INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN
|
||
NO EVENT SHALL NCR BE LIABLE FOR ANY SPECIAL, INDIRECT OR
|
||
CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
|
||
OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
|
||
NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
|
||
CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
|
||
</para>
|
||
|
||
</legalnotice>
|
||
|
||
<legalnotice>
|
||
<para>
|
||
Copyright © 1993, 1994, 2002 The Open Group
|
||
</para>
|
||
|
||
<para>
|
||
Permission is hereby granted, free of charge, to any person obtaining a copy
|
||
of this software and associated documentation files (the “Software”), to deal
|
||
in the Software without restriction, including without limitation the rights
|
||
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
|
||
copies of the Software, and to permit persons to whom the Software is
|
||
furnished to do so, subject to the following conditions:
|
||
</para>
|
||
|
||
<para>
|
||
The above copyright notice and this permission notice shall be included in
|
||
all copies or substantial portions of the Software.
|
||
</para>
|
||
|
||
<para>
|
||
THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
||
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
||
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
|
||
OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
|
||
AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
|
||
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
|
||
</para>
|
||
|
||
<para>
|
||
Except as contained in this notice, the name of The Open Group shall not be
|
||
used in advertising or otherwise to promote the sale, use or other dealings
|
||
in this Software without prior written authorization from The Open Group.
|
||
</para>
|
||
|
||
<para>
|
||
X Window System is a trademark of The Open Group, Inc.
|
||
</para>
|
||
|
||
</legalnotice>
|
||
|
||
</bookinfo>
|
||
|
||
<preface><title>The X Transport Interface</title>
|
||
<para>
|
||
Designed by Stuart Anderson (NCR) with help from Ralph Mor (X Consortium)
|
||
</para>
|
||
|
||
<note><para>
|
||
This documentation does not completely match the implementation in R6
|
||
(as a result of some late changes made in the code). Specifically, support
|
||
was added for font server cloning, and conditional compliation was introduced
|
||
for client vs. server code.
|
||
</para></note>
|
||
</preface>
|
||
|
||
<chapter id='purposes_and_goals'>
|
||
<title>Purposes and Goals</title>
|
||
|
||
<para>The X Transport Interface is intended to combine all system and
|
||
transport specific code into a single place in the source tree. This API
|
||
should be used by all libraries, clients and servers of the X Window System.
|
||
Use of this API should allow the addition of new types of transports and
|
||
support for new platforms without making any changes to the source except
|
||
in the X Transport Interface code.</para>
|
||
<para>This interface should solve the problem of multiple
|
||
<code>#ifdef TRANSPORT</code> and <code>#ifdef PLATFORM</code>
|
||
statements scattered throughout the source tree.</para>
|
||
<para>This interface should provide enough functionality to support all
|
||
types of protocols, including connection oriented protocols such as X11 and
|
||
FS, and connection-less oriented protocols such as XDMCP.</para>
|
||
|
||
</chapter>
|
||
|
||
<chapter id='overview_of_the_interface'>
|
||
<title>Overview of the Interface</title>
|
||
|
||
<para>
|
||
The interface provides an API for use by applications. The functions in
|
||
this API perform work that is common to all transports and systems, such
|
||
as parsing an address into a host and port number. The functions in this
|
||
API call transport specific functions that are contained in a table whose
|
||
contents are defined at compile time. This table contains an entry for each
|
||
type of transport. Each entry is a record containing mostly pointers to
|
||
function that implements the interface for the given transport.
|
||
</para>
|
||
<para>
|
||
This API does not provide an abstraction for <function>select()</function>
|
||
or <function>poll()</function>.
|
||
These functions are themselves transport independent, so an additional
|
||
interface is not needed for these functions. It is also unclear how such
|
||
an interface would affect performance.
|
||
</para>
|
||
</chapter>
|
||
|
||
<chapter id='definition_of_address_specification_format'>
|
||
<title>Definition of Address Specification Format</title>
|
||
|
||
<para>
|
||
Addresses are specified in the following syntax,
|
||
|
||
<synopsis>
|
||
<replaceable>protocol</replaceable>/<replaceable>host</replaceable>:<replaceable>port</replaceable>
|
||
</synopsis>
|
||
|
||
where <replaceable>protocol</replaceable> specifies a protocol family
|
||
or an alias for a protocol family. A definition of common protocol
|
||
families is given in a later section.
|
||
</para>
|
||
<para>
|
||
The <replaceable>host</replaceable> part specifies the name of a host or other
|
||
transport dependent entity that could be interpreted as a Network Service Access Point
|
||
(NSAP).
|
||
</para>
|
||
<para>
|
||
The <replaceable>port</replaceable> part specifies the name of a Transport Service
|
||
Access Point (TSAP). The format of the TSAP is defined by the underlying transport
|
||
implementation, but it is represented using a string format when it is
|
||
part of an address.
|
||
</para>
|
||
</chapter>
|
||
|
||
<chapter id='internal_data_structures'>
|
||
<title>Internal Data Structures</title>
|
||
<para>
|
||
There are two major data structures associated with the transport
|
||
independent portion of this interface. Additional data structures
|
||
may be used internally by each transport.
|
||
</para>
|
||
<sect1 id="xtransport">
|
||
<title>Xtransport</title>
|
||
<para>
|
||
Each transport supported has an entry in the transport table. The transport
|
||
table is an array of Xtransport records. Each record contains all the entry
|
||
points for a single transport. This record is defined as:
|
||
</para>
|
||
|
||
<synopsis>
|
||
typedef struct _Xtransport {
|
||
|
||
char *TransName;
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||
int flags;
|
||
|
||
XtransConnInfo (*OpenCOTSClient)(
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||
struct _Xtransport *, /* transport */
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||
char *, /* protocol */
|
||
char *, /* host */
|
||
char * /* port */
|
||
);
|
||
|
||
XtransConnInfo (*OpenCOTSServer)(
|
||
struct _Xtransport *, /* transport */
|
||
char *, /* protocol */
|
||
char *, /* host */
|
||
char * /* port */
|
||
);
|
||
|
||
XtransConnInfo (*OpenCLTSClient)(
|
||
struct _Xtransport *, /* transport */
|
||
char *, /* protocol */
|
||
char *, /* host */
|
||
char * /* port */
|
||
);
|
||
|
||
XtransConnInfo (*OpenCLTSServer)(
|
||
struct _Xtransport *, /* transport */
|
||
char *, /* protocol */
|
||
char *, /* host */
|
||
char * /* port */
|
||
);
|
||
|
||
int (*SetOption)(
|
||
XtransConnInfo, /* connection */
|
||
int, /* option */
|
||
int /* arg */
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||
);
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||
|
||
int (*CreateListener)(
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||
XtransConnInfo, /* connection */
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||
char *, /* port */
|
||
int /* flags */
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||
);
|
||
|
||
int (*ResetListener)(
|
||
XtransConnInfo /* connection */
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||
);
|
||
|
||
XtransConnInfo (*Accept)(
|
||
XtransConnInfo /* connection */
|
||
);
|
||
|
||
int (*Connect)(
|
||
XtransConnInfo, /* connection */
|
||
char *, /* host */
|
||
char * /* port */
|
||
);
|
||
|
||
int (*BytesReadable)(
|
||
XtransConnInfo, /* connection */
|
||
BytesReadable_t * /* pend */
|
||
);
|
||
|
||
int (*Read)(
|
||
XtransConnInfo, /* connection */
|
||
char *, /* buf */
|
||
int /* size */
|
||
);
|
||
|
||
int (*Write)(
|
||
XtransConnInfo, /* connection */
|
||
char *, /* buf */
|
||
int /* size */
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||
);
|
||
|
||
int (*Readv)(
|
||
XtransConnInfo, /* connection */
|
||
struct iovec *, /* buf */
|
||
int /* size */
|
||
);
|
||
|
||
int (*Writev)(
|
||
XtransConnInfo, /* connection */
|
||
struct iovec *, /* buf */
|
||
int /* size */
|
||
);
|
||
|
||
int (*Disconnect)(
|
||
XtransConnInfo /* connection */
|
||
);
|
||
|
||
int (*Close)(
|
||
XtransConnInfo /* connection */
|
||
);
|
||
|
||
} Xtransport;
|
||
</synopsis>
|
||
|
||
<para>
|
||
The <structfield>flags</structfield> field can contain an OR of
|
||
the following masks:
|
||
<variablelist>
|
||
<varlistentry>
|
||
<term><symbol>TRANS_ALIAS</symbol></term>
|
||
<listitem><para>
|
||
indicates that this record is providing an alias, and should
|
||
not be used to create a listener.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term><symbol>TRANS_LOCAL</symbol></term>
|
||
<listitem><para>
|
||
indicates that this is a <symbol>LOCALCONN</symbol> transport.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term><symbol>TRANS_ABSTRACT</symbol></term>
|
||
<listitem><para>
|
||
indicates that a local connection transport uses the abstract socket namespace.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
</variablelist>
|
||
</para>
|
||
|
||
<para>
|
||
Some additional flags may be set in the <structfield>flags</structfield>
|
||
field by the library while it is running:
|
||
<variablelist>
|
||
<varlistentry>
|
||
<term><symbol>TRANS_DISABLED</symbol></term>
|
||
<listitem><para>
|
||
indicates that this transport has been disabled.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term><symbol>TRANS_NOLISTEN</symbol></term>
|
||
<listitem><para>
|
||
indicates that servers should not open new listeners using this transport.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term><symbol>TRANS_NOUNLINK</symbol></term>
|
||
<listitem><para>
|
||
set by a transport backend to indicate that the endpoints for its connection
|
||
should not be unlinked.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
</variablelist>
|
||
</para>
|
||
</sect1>
|
||
|
||
<sect1 id="xtransconninfo">
|
||
<title>XtransConnInfo</title>
|
||
<para>
|
||
Each connection will have an opaque <structname>XtransConnInfo</structname>
|
||
transport connection
|
||
object allocated for it. This record contains information specific to the
|
||
connection. The record is defined as:
|
||
|
||
<synopsis>
|
||
typedef struct _XtransConnInfo *XtransConnInfo;
|
||
|
||
struct _XtransConnInfo {
|
||
struct _Xtransport *transptr;
|
||
char *priv;
|
||
int flags;
|
||
int fd;
|
||
int family;
|
||
char *addr;
|
||
int addrlen;
|
||
char *peeraddr;
|
||
int peeraddrlen;
|
||
};
|
||
</synopsis>
|
||
</para>
|
||
</sect1>
|
||
</chapter>
|
||
|
||
<chapter id='exposed_transport_independent_api'>
|
||
<title>Exposed Transport Independent API</title>
|
||
|
||
<para>
|
||
This API is included in each library and server that uses it. The API may
|
||
be used by the library, but it is not added to the public API for that
|
||
library. This interface is simply an implementation facilitator. This API
|
||
contains a low level set of core primitives, and a few utility functions
|
||
that are built on top of the primitives. The utility functions exist to
|
||
provide a more familiar interface that can be used to port existing code.
|
||
</para>
|
||
<para>
|
||
A macro is defined in Xtrans.h for TRANS(func) that creates a unique function
|
||
name depending on where the code is compiled. For example, when built for
|
||
Xlib, TRANS(OpenCOTSClient) becomes <function>_X11TransOpenCOTSClient</function>.
|
||
</para>
|
||
<para>
|
||
All failures are considered fatal, and the connection should be closed
|
||
and re-established if desired. In most cases, however, the value of
|
||
errno will be available for debugging purposes.
|
||
</para>
|
||
<sect1 id="core_interface_api">
|
||
<title>Core Interface API</title>
|
||
<itemizedlist mark='bullet'>
|
||
<listitem>
|
||
<para>
|
||
XtransConnInfo TRANS(OpenCOTSClient)(char *address)
|
||
</para>
|
||
<para>
|
||
This function creates a Connection-Oriented Transport that is
|
||
suitable for use by a client. The parameter <parameter>address</parameter>
|
||
contains the full address of the server to which this endpoint will be connected. This
|
||
functions returns an opaque transport connection object on success, or
|
||
NULL on failure.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
XtransConnInfo TRANS(OpenCOTSServer)(char *address)
|
||
</para>
|
||
<para>
|
||
This function creates a Connection-Oriented Transport that is suitable
|
||
for use by a server. The parameter <parameter>address</parameter> contains the
|
||
full address to which this server will be bound. This functions returns an opaque
|
||
transport connection object on success, or NULL on failure.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
XtransConnInfo TRANS(OpenCLTSClient)(char *address)
|
||
</para>
|
||
<para>
|
||
This function creates a Connection-Less Transport that is suitable for
|
||
use by a client. The parameter <parameter>address</parameter> contains the
|
||
full address of the server to which this endpoint will be connected. This functions
|
||
returns an opaque transport connection object on success, or NULL on failure.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
XtransConnInfo TRANS(OpenCLTSServer)(char *address)
|
||
</para>
|
||
<para>
|
||
This function creates a Connection-Less Transport that is suitable for
|
||
use by a server. The parameter <parameter>address</parameter> contains the
|
||
full address to which this server will be bound. This functions returns an opaque
|
||
transport connection object on success, or NULL on failure.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
int TRANS(SetOption)(XtransConnInfo connection, int option, int arg)
|
||
</para>
|
||
<para>
|
||
This function sets transport options, similar to the way
|
||
<function>setsockopt()</function> and <function>ioctl()</function> work.
|
||
The parameter <parameter>connection</parameter> is an endpoint
|
||
that was obtained from _XTransOpen*() functions. The parameter
|
||
<parameter>option</parameter> contains the option that will be set. The actual
|
||
values for option are defined in a later section. The parameter
|
||
<parameter>arg</parameter> can be used to pass in an additional value that may
|
||
be required by some options. This function return 0 on
|
||
success and -1 on failure.
|
||
</para>
|
||
<note><para>
|
||
Based on current usage, the complimentary function
|
||
<function>TRANS(GetOption)</function> is not necessary.
|
||
</para></note>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
int TRANS(CreateListener)(XtransConnInfo connection, char *port, int flags)
|
||
</para>
|
||
<para>
|
||
This function sets up the server endpoint for listening. The parameter
|
||
<parameter>connection</parameter> is an endpoint that was obtained from
|
||
<function>TRANS(OpenCOTSServer)()</function> or
|
||
<function>TRANS(OpenCLTSServer)()</function>. The parameter
|
||
<parameter>port</parameter> specifies the
|
||
port to which this endpoint should be bound for listening. If port is NULL,
|
||
then the transport may attempt to allocate any available TSAP for this
|
||
connection. If the transport cannot support this, then this function will
|
||
return a failure. The <parameter>flags</parameter> parameter can be set
|
||
to <symbol>ADDR_IN_USE_ALLOWED</symbol> to allow the call to the underlying
|
||
binding function to fail with a <errorname>EADDRINUSE</errorname> error
|
||
without causing the <function>TRANS(CreateListener)</function>
|
||
function itself to fail. This function return 0 on success and -1 on failure.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
int TRANS(ResetListener)(XtransConnInfo connection)
|
||
</para>
|
||
<para>
|
||
When a server is restarted, certain listen ports may need to be reset.
|
||
For example, unix domain needs to check that the file used for
|
||
communication has not been deleted. If it has, it must be recreated.
|
||
The parameter <parameter>connection</parameter> is an opened and bound
|
||
endpoint that was obtained from <function>TRANS(OpenCOTSServer)()</function>
|
||
and passed to <function>TRANS(CreateListener)()</function>.
|
||
This function will return one of the following values:
|
||
<symbol>TRANS_RESET_NOOP</symbol>,
|
||
<symbol>TRANS_RESET_NEW_FD</symbol>, or
|
||
<symbol>TRANS_RESET_FAILURE</symbol>.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
XtransConnInfo TRANS(Accept)(XtransConnInfo connection)
|
||
</para>
|
||
<para>
|
||
Once a connection indication is received, this function can be called to
|
||
accept the connection. The parameter <parameter>connection</parameter> is
|
||
an opened and bound endpoint that was obtained from
|
||
<function>TRANS(OpenCOTSServer)()</function> and passed to
|
||
<function>TRANS(CreateListener)()</function>. This function will return a
|
||
new opaque transport connection object upon success, NULL otherwise.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
int TRANS(Connect)(XtransConnInfo connection, char *address)
|
||
</para>
|
||
<para>
|
||
This function creates a connection to a server. The parameter
|
||
<parameter>connection</parameter> is an endpoint that was obtained
|
||
from <function>TRANS(OpenCOTSClient)()</function>. The parameter
|
||
<parameter>address</parameter> specifies the TSAP to which this endpoint
|
||
should connect. If the
|
||
protocol is included in the address, it will be ignored. This function
|
||
return 0 on success and -1 on failure.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
int TRANS(BytesReadable)(XtransConnInfo connection, BytesReadable_t *pend);
|
||
</para>
|
||
<para>
|
||
This function provides the same functionality as the BytesReadable macro.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
int TRANS(Read)(XtransConnInfo connection, char *buf, int size)
|
||
</para>
|
||
<para>
|
||
This function will return the number of bytes requested on a COTS
|
||
connection, and will return the minimum of the number bytes requested or
|
||
the size of the incoming packet on a CLTS connection.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
int TRANS(Write)(XtransConnInfo connection, char *buf, int size)
|
||
</para>
|
||
<para>
|
||
This function will write the requested number of bytes on a COTS
|
||
connection, and will send a packet of the requested size on a CLTS connection.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
int TRANS(Readv)(XtransConnInfo connection, struct iovec *buf, int size)
|
||
</para>
|
||
<para>
|
||
Similar to <function>TRANS(Read)()</function>.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
int TRANS(Writev)(XtransConnInfo connection, struct iovec *buf, int size)
|
||
</para>
|
||
<para>
|
||
Similar to <function>TRANS(Write)()</function>.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
int TRANS(Disconnect)(XtransConnInfo connection)
|
||
</para>
|
||
<para>
|
||
This function is used when an orderly disconnect is desired. This function
|
||
breaks the connection on the transport. It is similar to the socket function
|
||
<function>shutdown()</function>.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
int TRANS(Close)(XtransConnInfo connection)
|
||
</para>
|
||
<para>
|
||
This function closes the transport, unbinds it, and frees all resources that
|
||
was associated with the transport. If a <function>TRANS(Disconnect)</function>
|
||
call was not made on the connection, a disorderly disconnect may occur.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
int TRANS(IsLocal)(XtransConnInfo connection)
|
||
</para>
|
||
<para>
|
||
Returns TRUE if it is a local transport.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
int TRANS(GetMyAddr)(XtransConnInfo connection, int *familyp, int *addrlenp,
|
||
Xtransaddr **addrp)
|
||
</para>
|
||
<para>
|
||
This function is similar to
|
||
<function>getsockname()</function>.
|
||
This function will allocate space for the address, so it must be freed by
|
||
the caller. Not all transports will have a valid address until a connection
|
||
is established. This function should not be used until the connection is
|
||
established with
|
||
<function>Connect()</function> or
|
||
<function>Accept()</function>.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
int TRANS(GetPeerAddr)(XtransConnInfo connection, int *familyp, int *addrlenp,
|
||
Xtransaddr **addrp)
|
||
</para>
|
||
<para>
|
||
This function is similar to
|
||
<function>getpeername()</function>.
|
||
This function will allocate space for the address, so it must be freed by
|
||
the caller. Not all transports will have a valid address until a connection
|
||
is established. This function should not be used until the connection is
|
||
established with
|
||
<function>Connect()</function> or
|
||
<function>Accept()</function>.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
int TRANS(GetConnectionNumber)(XtransConnInfo connection)
|
||
</para>
|
||
<para>
|
||
Returns the file descriptor associated with this transport.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
int TRANS(MakeAllCOTSServerListeners)(char *port, int *partial_ret,
|
||
int *count_ret, XtransConnInfo **connections_ret)
|
||
</para>
|
||
<para>
|
||
This function should be used by most servers. It will try to establish
|
||
a COTS server endpoint for each transport listed in the transport table.
|
||
<parameter>partial_ret</parameter> will be set to <symbol>True</symbol> if
|
||
only a partial network could be created. <parameter>count_ret</parameter> is
|
||
the number of transports returned, and <parameter>connections_ret</parameter>
|
||
is the list of transports.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
int TRANS(MakeAllCLTSServerListeners)( char *port, int *partial_ret,
|
||
int *count_ret, XtransConnInfo **connections_ret)
|
||
</para>
|
||
<para>
|
||
This function should be used by most servers. It will try to establish a
|
||
CLTS server endpoint for each transport listed in the transport table.
|
||
<parameter>partial_ret</parameter> will be set to <symbol>True</symbol> if
|
||
only a partial network could be created. <parameter>count_ret</parameter> is
|
||
the number of transports returned, and <parameter>connections_ret</parameter>
|
||
is the list of transports.
|
||
</para>
|
||
</listitem>
|
||
</itemizedlist>
|
||
</sect1>
|
||
|
||
<sect1 id="utility_api">
|
||
<title>Utility API</title>
|
||
<para>
|
||
This section describes a few useful functions that have been implemented on
|
||
top of the Core Interface API. These functions are being provided as a
|
||
convenience.
|
||
</para>
|
||
<itemizedlist mark='bullet'>
|
||
<listitem>
|
||
<para>
|
||
int TRANS(ConvertAddress)(int *familyp, int *addrlenp, Xtransaddr *addrp)
|
||
</para>
|
||
<para>
|
||
This function converts a sockaddr based address to an X authorization based
|
||
address (ie AF_INET, AF_UNIX to the X protocol definition (ie FamilyInternet,
|
||
FamilyLocal)).
|
||
</para>
|
||
</listitem>
|
||
</itemizedlist>
|
||
</sect1>
|
||
</chapter>
|
||
|
||
<chapter id="transport_option_definition">
|
||
<title>Transport Option Definition</title>
|
||
<para>
|
||
The following options are defined for the
|
||
<function>TRANS(SetOption)()</function>
|
||
function. If an OS or transport does not support any of these options,
|
||
then it will silently ignore the option.
|
||
</para>
|
||
|
||
<itemizedlist mark='bullet'>
|
||
<listitem>
|
||
<para>
|
||
<symbol>TRANS_NONBLOCKING</symbol>
|
||
</para>
|
||
<para>
|
||
This option controls the blocking mode of the connection. If the argument
|
||
is set to 1, then the connection will be set to blocking. If the argument
|
||
is set to 0, then the connection will be set to non- blocking.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
<symbol>TRANS_CLOSEONEXEC</symbol>
|
||
</para>
|
||
<para>
|
||
This option determines what will happen to the connection when an exec is
|
||
encountered. If the argument is set to 1, then the connection will be
|
||
closed when an exec occurs. If the argument is set to 0, then the
|
||
connection will not be closed when an exec occurs.
|
||
</para>
|
||
</listitem>
|
||
</itemizedlist>
|
||
</chapter>
|
||
|
||
<chapter id="hidden_transport_dependent_api">
|
||
<title>Hidden Transport Dependent API</title>
|
||
<para>
|
||
The hidden transport dependent functions are placed in the Xtransport record.
|
||
These function are similar to the Exposed Transport Independent API, but
|
||
some of the parameters and return values are slightly different. Stuff like
|
||
the <code>#ifdef SUNSYSV</code> should be handled inside these functions.
|
||
</para>
|
||
|
||
<itemizedlist mark='bullet'>
|
||
<listitem>
|
||
<para>
|
||
XtransConnInfo *OpenCOTSClient (
|
||
struct _Xtransport *thistrans, char *protocol, char *host, char *port)
|
||
</para>
|
||
<para>
|
||
This function creates a Connection-Oriented Transport. The parameter
|
||
<parameter>thistrans</parameter>
|
||
points to an Xtransport entry in the transport table. The parameters
|
||
<parameter>protocol</parameter>,
|
||
<parameter>host</parameter>, and
|
||
<parameter>port</parameter>, point to strings containing the corresponding
|
||
parts of the address that was passed into <function>TRANS(OpenCOTSClient)()</function>.
|
||
This function must allocate and initialize the contents of the XtransConnInfo
|
||
structure that is returned by this function. This function will open the
|
||
transport, and bind it into the transport namespace if applicable. The local
|
||
address portion of the XtransConnInfo structure will also be filled in by
|
||
this function.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
XtransConnInfo *OpenCOTSServer (
|
||
struct _Xtransport *thistrans, char *protocol, char *host, char *port)
|
||
</para>
|
||
<para>
|
||
This function creates a Connection-Oriented Transport. The parameter
|
||
<parameter>thistrans</parameter>
|
||
points to an Xtransport entry in the transport table. The
|
||
parameters
|
||
<parameter>protocol</parameter>,
|
||
<parameter>host</parameter>, and
|
||
<parameter>port</parameter> point to strings containing the
|
||
corresponding parts of the address that was passed into
|
||
<function>TRANS(OpenCOTSClient)()</function>.
|
||
This function must allocate and initialize the contents of the
|
||
XtransConnInfo structure that is returned by this function. This function
|
||
will open the transport.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
XtransConnInfo *OpenCLTSClient (
|
||
struct _Xtransport *thistrans, char *protocol, char *host, char *port)
|
||
</para>
|
||
<para>
|
||
This function creates a Connection-Less Transport. The parameter
|
||
<parameter>thistrans</parameter>
|
||
points to an Xtransport entry in the transport table. The parameters
|
||
<parameter>protocol</parameter>,
|
||
<parameter>host</parameter>, and
|
||
<parameter>port</parameter> point to strings containing the
|
||
corresponding parts of the address that was passed into
|
||
<function>TRANS(OpenCOTSClient)()</function>.
|
||
This function must allocate and initialize the contents of the XtransConnInfo
|
||
structure that is returned by this function. This function will open the
|
||
transport, and bind it into the transport namespace if applicable. The
|
||
local address portion of the XtransConnInfo structure will also be filled
|
||
in by this function.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
XtransConnInfo *OpenCLTSServer (
|
||
struct _Xtransport *thistrans, char *protocol, char *host, char *port)
|
||
</para>
|
||
<para>
|
||
This function creates a Connection-Less Transport. The parameter
|
||
<parameter>thistrans</parameter>
|
||
points to an Xtransport entry in the transport table. The parameters
|
||
<parameter>protocol</parameter>,
|
||
<parameter>host</parameter>, and
|
||
<parameter>port</parameter> point to strings containing the
|
||
corresponding parts of the address that was passed into
|
||
<function>TRANS(OpenCOTSClient)()</function>.
|
||
This function must allocate and initialize the contents of the
|
||
XtransConnInfo structure that is returned by this function. This
|
||
function will open the transport.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
int SetOption (struct _Xtransport *thistrans, int option, int arg)
|
||
</para>
|
||
<para>
|
||
This function provides a transport dependent way of implementing the
|
||
options defined by the X Transport Interface. In the current prototype,
|
||
this function is not being used, because all of the options defined so far
|
||
are transport independent. This function will have to be used if a radically
|
||
different transport type is added, or a transport dependent option is defined.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
int CreateListener (struct _Xtransport *thistrans, char *port, int flags )
|
||
</para>
|
||
<para>
|
||
This function takes a transport endpoint opened for a server, and sets it
|
||
up to listen for incoming connection requests. The parameter
|
||
<parameter>port</parameter>
|
||
contains the port portion of the address that was passed to the Open function.
|
||
The parameter <parameter>flags</parameter> should be set to
|
||
<symbol>ADDR_IN_USE_ALLOWED</symbol> if the underlying transport endpoint
|
||
may be already bound and this should not be considered
|
||
as an error. Otherwise flags should be set to 0. This is used by IPv6 code,
|
||
where the same socket can be bound to both an IPv6 address and then to a
|
||
IPv4 address. This function will bind the transport into the transport
|
||
name space if applicable, and fill in the local address portion of the
|
||
XtransConnInfo structure. The transport endpoint will then be set to
|
||
listen for incoming connection requests.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
int ResetListener (struct _Xtransport *thistrans)
|
||
</para>
|
||
<para>
|
||
This function resets the transport for listening.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
XtransConnInfo Accept(struct _Xtransport *thistrans)
|
||
</para>
|
||
<para>
|
||
This function creates a new transport endpoint as a result of an
|
||
incoming connection request. The parameter
|
||
<parameter>thistrans</parameter> is the endpoint
|
||
that was opened for listening by the server. The new endpoint is
|
||
opened and bound into the transport’s namespace. A XtransConnInfo
|
||
structure describing the new endpoint is returned from this function
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
int Connect(struct _Xtransport *thistrans, char *host, char *port )
|
||
</para>
|
||
<para>
|
||
This function establishes a connection to a server. The parameters
|
||
<parameter>host</parameter> and
|
||
<parameter>port</parameter>
|
||
describe the server to which the connection should be
|
||
established. The connection will be established so that
|
||
<function>Read()</function> and
|
||
<function>Write()</function> call can be made.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
int BytesReadable(struct _Xtransport *thistrans, BytesReadable_t *pend )
|
||
</para>
|
||
<para>
|
||
This function replaces the
|
||
<function>BytesReadable()</function>
|
||
macro. This allows each transport to have it’s own mechanism for determining
|
||
how much data is ready to be read.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
int Read(struct _Xtransport *thistrans, char *buf, int size )
|
||
</para>
|
||
<para>
|
||
This function reads size bytes into buf from the connection.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
int Write(struct _Xtransport *thistrans, char *buf, int size )
|
||
</para>
|
||
<para>
|
||
This function writes size bytes from buf to the connection.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
int Readv(struct _Xtransport *thistrans, struct iovec *buf, int size )
|
||
</para>
|
||
<para>
|
||
This function performs a <function>readv()</function> on the connection.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
int Writev(struct _Xtransport *thistrans, struct iovec *buf, int size )
|
||
</para>
|
||
<para>
|
||
This function performs a <function>writev()</function> on the connection.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
int Disconnect(struct _Xtransport *thistrans)
|
||
</para>
|
||
<para>
|
||
This function initiates an orderly shutdown of a connection. If a
|
||
transport does not distinguish between orderly and disorderly
|
||
disconnects, then a call to this function will have no affect.
|
||
</para>
|
||
</listitem>
|
||
<listitem>
|
||
<para>
|
||
int Close(struct _Xtransport *thistrans)
|
||
</para>
|
||
<para>
|
||
This function will break the connection, and close the endpoint.
|
||
</para>
|
||
</listitem>
|
||
</itemizedlist>
|
||
</chapter>
|
||
<chapter id="configuration">
|
||
<title>Configuration</title>
|
||
|
||
<para>
|
||
The implementation of each transport can be platform specific. It is expected
|
||
that existing connection types such as <symbol>TCPCONN</symbol>,
|
||
<symbol>UNIXCONN</symbol>, <symbol>LOCALCONN</symbol>, and
|
||
<symbol>STREAMSCONN</symbol> will be replaced with flags for each
|
||
possible transport type.
|
||
</para>
|
||
<para>
|
||
In X11R6, the below flags to enable transport types were set in
|
||
<symbol>ConnectionFlags</symbol> in the <filename>vendor.cf</filename> or
|
||
<filename>site.def</filename> config files.
|
||
</para>
|
||
<para>
|
||
In X11R7 modular releases, these flags are set when running
|
||
<filename>configure</filename> scripts which include the
|
||
<function>XTRANS_CONNECTION_FLAGS</function> macro from
|
||
<filename>xtrans.m4</filename>.
|
||
</para>
|
||
<informaltable pgwide='0' frame='none'>
|
||
<tgroup cols='4' align='left'>
|
||
<colspec colname='define' align='center'/>
|
||
<colspec colname='enable'/>
|
||
<colspec colname='desc'/>
|
||
<thead>
|
||
<row>
|
||
<entry><code>#define</code></entry>
|
||
<entry>configure flag</entry>
|
||
<entry>Description</entry>
|
||
</row>
|
||
</thead>
|
||
<tbody>
|
||
<row>
|
||
<entry><symbol>TCPCONN</symbol></entry>
|
||
<entry><option>--enable-tcp-transport</option></entry>
|
||
<entry>
|
||
Enables the INET (IPv4) Domain Socket based transport
|
||
</entry>
|
||
</row>
|
||
<row>
|
||
<entry><symbol>IPv6</symbol></entry>
|
||
<entry><option>--enable-ipv6</option></entry>
|
||
<entry>
|
||
Extends <symbol>TCPCONN</symbol> to enable IPv6 Socket based transport
|
||
</entry>
|
||
</row>
|
||
<row>
|
||
<entry><symbol>UNIXCONN</symbol></entry>
|
||
<entry><option>--enable-unix-transport</option></entry>
|
||
<entry>
|
||
Enables the UNIX Domain Socket based transport
|
||
</entry>
|
||
</row>
|
||
<row>
|
||
<entry><symbol>STREAMSCONN</symbol></entry>
|
||
<entry><emphasis>Not available in X11R7</emphasis></entry>
|
||
<entry>
|
||
Enables the TLI based transports
|
||
</entry>
|
||
</row>
|
||
<row>
|
||
<entry><symbol>LOCALCONN</symbol></entry>
|
||
<entry><option>--enable-local-transport</option></entry>
|
||
<entry>
|
||
Enables the SYSV Local connection transports
|
||
</entry>
|
||
</row>
|
||
<row>
|
||
<entry><symbol>DNETCONN</symbol></entry>
|
||
<entry><emphasis>Not available in X11R7</emphasis></entry>
|
||
<entry>
|
||
Enables the DECnet transports
|
||
</entry>
|
||
</row>
|
||
</tbody>
|
||
</tgroup>
|
||
</informaltable>
|
||
|
||
|
||
</chapter>
|
||
|
||
<chapter id="transport_specific_definitions">
|
||
<title>Transport Specific Definitions</title>
|
||
|
||
<informaltable pgwide='0' frame='none'>
|
||
<tgroup cols='4' align='center'>
|
||
<colspec colname='c1'/>
|
||
<colspec colname='c2'/>
|
||
<colspec colname='c3'/>
|
||
<colspec colname='c4'/>
|
||
<thead>
|
||
<row>
|
||
<entry morerows="1" align='center'>Protocol Family</entry>
|
||
<entry namest="c2" nameend="c4" align='center'>Address Component</entry>
|
||
</row>
|
||
<row>
|
||
<entry align='center'>protocol</entry>
|
||
<entry align='center'>host</entry>
|
||
<entry align='center'>port</entry>
|
||
</row>
|
||
</thead>
|
||
<tbody>
|
||
<row>
|
||
<entry align='center'>Internet</entry>
|
||
<entry align='center'>inet inet6 tcp udp</entry>
|
||
<entry align='center'>name of an internet addressable host</entry>
|
||
<entry align='center'>string containing the name of a service or a valid port number. Example: "xserver0", "7100"</entry>
|
||
</row>
|
||
<row>
|
||
<entry align='center'>DECnet</entry>
|
||
<entry align='center'>decnet</entry>
|
||
<entry align='center'>name of a DECnet addressable host</entry>
|
||
<entry align='center'>string containing the complete name of the object. Example: "X$X0"</entry>
|
||
</row>
|
||
<row>
|
||
<entry align='center'>NETware</entry>
|
||
<entry align='center'>ipx</entry>
|
||
<entry align='center'>name of a NETware addressable host</entry>
|
||
<entry align='center'>Not sure of the specifics yet.</entry>
|
||
</row>
|
||
<row>
|
||
<entry align='center'>OSI</entry>
|
||
<entry align='center'>osi</entry>
|
||
<entry align='center'>name of an OSI adressable host.</entry>
|
||
<entry align='center'>Not sure of the specifics yet.</entry>
|
||
</row>
|
||
<row>
|
||
<entry align='center'>Local</entry>
|
||
<entry align='center'>local pts named sco isc</entry>
|
||
<entry align='center'>(ignored)</entry>
|
||
<entry align='center'>String containing the port name, ie "xserver0", "fontserver0".</entry>
|
||
</row>
|
||
</tbody>
|
||
</tgroup>
|
||
</informaltable>
|
||
|
||
</chapter>
|
||
|
||
<chapter id="implementation_notes">
|
||
<title>Implementation Notes</title>
|
||
<para>
|
||
This section refers to the prototype implementation that is being developed
|
||
concurrently with this document. This prototype has been able to flush out many
|
||
details and problems as the specification was being developed.
|
||
</para>
|
||
<para>
|
||
In X11R6, all of the source code for this interface was located in
|
||
<filename>xc/lib/xtrans</filename>.
|
||
</para>
|
||
<para>
|
||
In X11R7, all of the source code for this interface is delivered via
|
||
the <systemitem>lib/libxtrans</systemitem> modular package from X.Org,
|
||
and is installed under
|
||
<filename><replaceable>${prefix}</replaceable>/X11/Xtrans</filename>
|
||
so that other modules may find it when they build.
|
||
</para>
|
||
<para>
|
||
All functions names in the source are of the format
|
||
<function>TRANS(func)()</function>. The
|
||
<function>TRANS()</function>
|
||
macro is defined as
|
||
<programlisting language="C">
|
||
#if (__STDC__ && !defined(UNIXCPP)) || defined(ANSICPP)
|
||
#define TRANS(func) _PROTOCOLTrans##func
|
||
#else
|
||
#define TRANS(func) _PROTOCOLTrans/**/func
|
||
#endif
|
||
</programlisting>
|
||
</para>
|
||
|
||
<para>
|
||
<symbol>PROTOCOL</symbol> will be uniquely defined in each directory
|
||
where this code is compiled.
|
||
<symbol>PROTOCOL</symbol> will be defined to be the name of the protocol
|
||
that is implemented by the library or server, such as X11, FS, and ICE.
|
||
</para>
|
||
|
||
<para>
|
||
All libraries and servers that use the X Transport Interface should have a new
|
||
file called <filename><replaceable>TRANSPORT</replaceable>trans.c</filename>.
|
||
This file will include the transports based on the configuration flags
|
||
provided by the <filename>configure</filename> script. Below is an
|
||
example <filename>xfstrans.c</filename> for the font server.
|
||
</para>
|
||
|
||
<programlisting language="C">
|
||
#include "config.h"
|
||
|
||
#define FONT_t 1
|
||
#define TRANS_REOPEN 1
|
||
#define TRANS_SERVER 1
|
||
|
||
#include <X11/Xtrans/transport.c>
|
||
</programlisting>
|
||
<para>
|
||
The source files for this interface are listed below.
|
||
</para>
|
||
|
||
<variablelist>
|
||
<varlistentry>
|
||
<term><filename>Xtrans.h</filename></term>
|
||
<listitem><para>
|
||
Function prototypes and defines for the Transport Independent API.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term><filename>Xtransint.h</filename></term>
|
||
<listitem><para>
|
||
Used by the interface implementation only.
|
||
Contains the internal data structures.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term><filename>Xtranssock.c</filename></term>
|
||
<listitem><para>
|
||
Socket implementation of the Transport Dependent API.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term><filename>Xtranstli.c</filename></term>
|
||
<listitem><para>
|
||
TLI implementation of the Transport Dependent API.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term><filename>Xtransdnet.c</filename></term>
|
||
<listitem><para>
|
||
DECnet implementation of the Transport Dependent API.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term><filename>Xtranslocal.c</filename></term>
|
||
<listitem><para>
|
||
Implementation of the Transport Dependent API for SYSV Local connections.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term><filename>Xtrans.c</filename></term>
|
||
<listitem><para>
|
||
Exposed Transport Independent API Functions.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term><filename>Xtransutil.c</filename></term>
|
||
<listitem><para>
|
||
Collection of Utility functions that use the X Transport Interface.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
</variablelist>
|
||
|
||
|
||
<para>
|
||
The file <filename>Xtransint.h</filename> contains much of the transport
|
||
related code that was previously in <filename>Xlibint.h</filename> and
|
||
<filename>Xlibnet.h</filename>.
|
||
This will make the definitions available for all transport users. This
|
||
should also obsolete the equivalent code in other libraries.
|
||
</para>
|
||
|
||
</chapter>
|
||
</book>
|