man/mann/socket.n - toolchains/skids - Git at Google

 '\"
 '\" Copyright (c) 1996 Sun Microsystems, Inc.
 '\" Copyright (c) 1998-1999 by Scriptics Corporation.
 '\"
 '\" See the file "license.terms" for information on usage and redistribution
 '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 '\"
 '\" RCS: @(#) $Id: socket.n,v 1.7 2002/10/01 10:03:19 dkf Exp $
 '\" The definitions below are for supplemental macros used in Tcl/Tk
 '\" manual entries.
 '\"
 '\" .AP type name in/out ?indent?
 '\"	Start paragraph describing an argument to a library procedure.
 '\"	type is type of argument (int, etc.), in/out is either "in", "out",
 '\"	or "in/out" to describe whether procedure reads or modifies arg,
 '\"	and indent is equivalent to second arg of .IP (shouldn't ever be
 '\"	needed;  use .AS below instead)
 '\"
 '\" .AS ?type? ?name?
 '\"	Give maximum sizes of arguments for setting tab stops.  Type and
 '\"	name are examples of largest possible arguments that will be passed
 '\"	to .AP later.  If args are omitted, default tab stops are used.
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 '\"	Start of list of standard options for a Tk widget.  The
 '\"	options follow on successive lines, in four columns separated
 '\"	by tabs.
 '\"
 '\" .SE
 '\"	End of list of standard options for a Tk widget.
 '\"
 '\" .OP cmdName dbName dbClass
 '\"	Start of description of a specific option.  cmdName gives the
 '\"	option's name as specified in the class command, dbName gives
 '\"	the option's name in the option database, and dbClass gives
 '\"	the option's class in the option database.
 '\"
 '\" .UL arg1 arg2
 '\"	Print arg1 underlined, then print arg2 normally.
 '\"
 '\" RCS: @(#) $Id: man.macros,v 1.4 2000/08/25 06:18:32 ericm Exp $
 '\"
 '\"	# Set up traps and other miscellaneous stuff for Tcl/Tk man pages.
 .if t .wh -1.3i ^B
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 .ie !"\\$4"" .TP \\$4
 .el \{\
 .   ie !"\\$2"" .TP \\n()Cu
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 .\}
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 .\".b
 .\}
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 .\}
 .el \}\
 \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
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 .LP
 See the \\fBoptions\\fR manual entry for details on the standard options.
 ..
 '\"	# OP - start of full description for a single option
 .de OP
 .LP
 .nf
 .ta 4c
 Command-Line Name:	\\fB\\$1\\fR
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 Database Class:	\\fB\\$3\\fR
 .fi
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 .TH socket n 8.0 Tcl "Tcl Built-In Commands"
 .BS
 '\" Note:  do not modify the .SH NAME line immediately below!
 .SH NAME
 socket \- Open a TCP network connection
 .SH SYNOPSIS
 .sp
 \fBsocket \fR?\fIoptions\fR? \fIhost port\fR
 .sp
 \fBsocket\fR \fB\-server \fIcommand\fR ?\fIoptions\fR? \fIport\fR
 .BE

 .SH DESCRIPTION
 .PP
 This command opens a network socket and returns a channel
 identifier that may be used in future invocations of commands like
 \fBread\fR, \fBputs\fR and \fBflush\fR.
 At present only the TCP network protocol is supported;  future
 releases may include support for additional protocols.
 The \fBsocket\fR command may be used to open either the client or
 server side of a connection, depending on whether the \fB\-server\fR
 switch is specified.

 .SH "CLIENT SOCKETS"
 .PP
 If the \fB\-server\fR option is not specified, then the client side of a
 connection is opened and the command returns a channel identifier
 that can be used for both reading and writing.
 \fIPort\fR and \fIhost\fR specify a port
 to connect to;  there must be a server accepting connections on
 this port.  \fIPort\fR is an integer port number
 (or service name, where supported and understood by the host operating
 system) and \fIhost\fR
 is either a domain-style name such as \fBwww.sunlabs.com\fR or
 a numerical IP address such as \fB127.0.0.1\fR.
 Use \fIlocalhost\fR to refer to the host on which the command is invoked.
 .PP
 The following options may also be present before \fIhost\fR
 to specify additional information about the connection:
 .TP
 \fB\-myaddr\fI addr\fR
 \fIAddr\fR gives the domain-style name or numerical IP address of
 the client-side network interface to use for the connection.
 This option may be useful if the client machine has multiple network
 interfaces.  If the option is omitted then the client-side interface
 will be chosen by the system software.
 .TP
 \fB\-myport\fI port\fR
 \fIPort\fR specifies an integer port number (or service name, where
 supported and understood by the host operating system) to use for the
 client's
 side of the connection.  If this option is omitted, the client's
 port number will be chosen at random by the system software.
 .TP
 \fB\-async\fR
 The \fB\-async\fR option will cause the client socket to be connected
 asynchronously. This means that the socket will be created immediately but
 may not yet be connected to the server, when the call to \fBsocket\fR
 returns. When a \fBgets\fR or \fBflush\fR is done on the socket before the
 connection attempt succeeds or fails, if the socket is in blocking mode, the
 operation will wait until the connection is completed or fails. If the
 socket is in nonblocking mode and a \fBgets\fR or \fBflush\fR is done on
 the socket before the connection attempt succeeds or fails, the operation
 returns immediately and \fBfblocked\fR on the socket returns 1.

 .SH "SERVER SOCKETS"
 .PP
 If the \fB\-server\fR option is specified then the new socket
 will be a server for the port given by \fIport\fR (either an integer
 or a service name, where supported and understood by the host
 operating system).
 Tcl will automatically accept connections to the given port.
 For each connection Tcl will create a new channel that may be used to
 communicate with the client.  Tcl then invokes \fIcommand\fR
 with three additional arguments: the name of the new channel, the
 address, in network address notation, of the client's host, and
 the client's port number.
 .PP
 The following additional option may also be specified before \fIhost\fR:
 .TP
 \fB\-myaddr\fI addr\fR
 \fIAddr\fR gives the domain-style name or numerical IP address of
 the server-side network interface to use for the connection.
 This option may be useful if the server machine has multiple network
 interfaces.  If the option is omitted then the server socket is bound
 to the special address INADDR_ANY so that it can accept connections from
 any interface.
 .PP
 Server channels cannot be used for input or output; their sole use is to
 accept new client connections. The channels created for each incoming
 client connection are opened for input and output. Closing the server
 channel shuts down the server so that no new connections will be
 accepted;  however, existing connections will be unaffected.
 .PP
 Server sockets depend on the Tcl event mechanism to find out when
 new connections are opened.  If the application doesn't enter the
 event loop, for example by invoking the \fBvwait\fR command or
 calling the C procedure \fBTcl_DoOneEvent\fR, then no connections
 will be accepted.
 .PP
 If \fIport\fR is specified as zero, the operating system will allocate
 an unused port for use as a server socket.  The port number actually
 allocated my be retrieved from the created server socket using the
 \fBfconfigure\fR command to retrieve the \fB\-sockname\fR option as
 described below.

 .SH "CONFIGURATION OPTIONS"
 The \fBfconfigure\fR command can be used to query several readonly
 configuration options for socket channels:
 .TP
 \fB\-error\fR
 This option gets the current error status of the given socket.  This
 is useful when you need to determine if an asynchronous connect
 operation succeeded.  If there was an error, the error message is
 returned.  If there was no error, an empty string is returned.
 .TP
 \fB\-sockname\fR
 This option returns a list of three elements, the address, the host name
 and the port number for the socket. If the host name cannot be computed,
 the second element is identical to the address, the first element of the
 list.
 .TP
 \fB\-peername\fR
 This option is not supported by server sockets. For client and accepted
 sockets, this option returns a list of three elements; these are the
 address, the host name and the port to which the peer socket is connected
 or bound. If the host name cannot be computed, the second element of the
 list is identical to the address, its first element.
 .PP

 .SH "SEE ALSO"
 flush(n), open(n), read(n)

 .SH KEYWORDS
 bind, channel, connection, domain name, host, network address, socket, tcp
	'\"
	'\" Copyright (c) 1996 Sun Microsystems, Inc.
	'\" Copyright (c) 1998-1999 by Scriptics Corporation.
	'\"
	'\" See the file "license.terms" for information on usage and redistribution
	'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
	'\"
	'\" RCS: @(#) $Id: socket.n,v 1.7 2002/10/01 10:03:19 dkf Exp $
	'\" The definitions below are for supplemental macros used in Tcl/Tk
	'\" manual entries.
	'\"
	'\" .AP type name in/out ?indent?
	'\" Start paragraph describing an argument to a library procedure.
	'\" type is type of argument (int, etc.), in/out is either "in", "out",
	'\" or "in/out" to describe whether procedure reads or modifies arg,
	'\" and indent is equivalent to second arg of .IP (shouldn't ever be
	'\" needed; use .AS below instead)
	'\"
	'\" .AS ?type? ?name?
	'\" Give maximum sizes of arguments for setting tab stops. Type and
	'\" name are examples of largest possible arguments that will be passed
	'\" to .AP later. If args are omitted, default tab stops are used.
	'\"
	'\" .BS
	'\" Start box enclosure. From here until next .BE, everything will be
	'\" enclosed in one large box.
	'\"
	'\" .BE
	'\" End of box enclosure.
	'\"
	'\" .CS
	'\" Begin code excerpt.
	'\"
	'\" .CE
	'\" End code excerpt.
	'\"
	'\" .VS ?version? ?br?
	'\" Begin vertical sidebar, for use in marking newly-changed parts
	'\" of man pages. The first argument is ignored and used for recording
	'\" the version when the .VS was added, so that the sidebars can be
	'\" found and removed when they reach a certain age. If another argument
	'\" is present, then a line break is forced before starting the sidebar.
	'\"
	'\" .VE
	'\" End of vertical sidebar.
	'\"
	'\" .DS
	'\" Begin an indented unfilled display.
	'\"
	'\" .DE
	'\" End of indented unfilled display.
	'\"
	'\" .SO
	'\" Start of list of standard options for a Tk widget. The
	'\" options follow on successive lines, in four columns separated
	'\" by tabs.
	'\"
	'\" .SE
	'\" End of list of standard options for a Tk widget.
	'\"
	'\" .OP cmdName dbName dbClass
	'\" Start of description of a specific option. cmdName gives the
	'\" option's name as specified in the class command, dbName gives
	'\" the option's name in the option database, and dbClass gives
	'\" the option's class in the option database.
	'\"
	'\" .UL arg1 arg2
	'\" Print arg1 underlined, then print arg2 normally.
	'\"
	'\" RCS: @(#) $Id: man.macros,v 1.4 2000/08/25 06:18:32 ericm Exp $
	'\"
	'\" # Set up traps and other miscellaneous stuff for Tcl/Tk man pages.
	.if t .wh -1.3i ^B
	.nr ^l \n(.l
	.ad b
	'\" # Start an argument description
	.de AP
	.ie !"\\$4"" .TP \\$4
	.el \{\
	. ie !"\\$2"" .TP \\n()Cu
	. el .TP 15
	.\}
	.ta \\n()Au \\n()Bu
	.ie !"\\$3"" \{\
	\&\\$1 \\fI\\$2\\fP (\\$3)
	.\".b
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	\&\\$1 \\fI\\$2\\fP
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	..
	'\" # define tabbing values for .AP
	.de AS
	.nr )A 10n
	.if !"\\$1"" .nr )A \\w'\\$1'u+3n
	.nr )B \\n()Au+15n
	.\"
	.if !"\\$2"" .nr )B \\w'\\$2'u+\\n()Au+3n
	.nr )C \\n()Bu+\\w'(in/out)'u+2n
	..
	.AS Tcl_Interp Tcl_CreateInterp in/out
	'\" # BS - start boxed text
	'\" # ^y = starting y location
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	.de BS
	.br
	.mk ^y
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	.\" Draw four-sided box normally, but don't draw top of
	.\" box if the box started on an earlier page.
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	\h'-1.5n'\L'\|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\l'\|0u-1.5n\(ul'
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	'\" # box/sidebar if in box/sidebar mode, then invoked standard
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	.\" Draw three-sided box if this is the box's first page,
	.\" draw two sides but no top otherwise.
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	.\}
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	..
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	.de SO
	.SH "STANDARD OPTIONS"
	.LP
	.nf
	.ta 5.5c 11c
	.ft B
	..
	'\" # SE - end of list of standard options
	.de SE
	.fi
	.ft R
	.LP
	See the \\fBoptions\\fR manual entry for details on the standard options.
	..
	'\" # OP - start of full description for a single option
	.de OP
	.LP
	.nf
	.ta 4c
	Command-Line Name: \\fB\\$1\\fR
	Database Name: \\fB\\$2\\fR
	Database Class: \\fB\\$3\\fR
	.fi
	.IP
	..
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	.de CS
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	..
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	.de CE
	.fi
	.RE
	..
	.de UL
	\\$1\l'\|0\(ul'\\$2
	..
	.TH socket n 8.0 Tcl "Tcl Built-In Commands"
	.BS
	'\" Note: do not modify the .SH NAME line immediately below!
	.SH NAME
	socket \- Open a TCP network connection
	.SH SYNOPSIS
	.sp
	\fBsocket \fR?\fIoptions\fR? \fIhost port\fR
	.sp
	\fBsocket\fR \fB\-server \fIcommand\fR ?\fIoptions\fR? \fIport\fR
	.BE

	.SH DESCRIPTION
	.PP
	This command opens a network socket and returns a channel
	identifier that may be used in future invocations of commands like
	\fBread\fR, \fBputs\fR and \fBflush\fR.
	At present only the TCP network protocol is supported; future
	releases may include support for additional protocols.
	The \fBsocket\fR command may be used to open either the client or
	server side of a connection, depending on whether the \fB\-server\fR
	switch is specified.

	.SH "CLIENT SOCKETS"
	.PP
	If the \fB\-server\fR option is not specified, then the client side of a
	connection is opened and the command returns a channel identifier
	that can be used for both reading and writing.
	\fIPort\fR and \fIhost\fR specify a port
	to connect to; there must be a server accepting connections on
	this port. \fIPort\fR is an integer port number
	(or service name, where supported and understood by the host operating
	system) and \fIhost\fR
	is either a domain-style name such as \fBwww.sunlabs.com\fR or
	a numerical IP address such as \fB127.0.0.1\fR.
	Use \fIlocalhost\fR to refer to the host on which the command is invoked.
	.PP
	The following options may also be present before \fIhost\fR
	to specify additional information about the connection:
	.TP
	\fB\-myaddr\fI addr\fR
	\fIAddr\fR gives the domain-style name or numerical IP address of
	the client-side network interface to use for the connection.
	This option may be useful if the client machine has multiple network
	interfaces. If the option is omitted then the client-side interface
	will be chosen by the system software.
	.TP
	\fB\-myport\fI port\fR
	\fIPort\fR specifies an integer port number (or service name, where
	supported and understood by the host operating system) to use for the
	client's
	side of the connection. If this option is omitted, the client's
	port number will be chosen at random by the system software.
	.TP
	\fB\-async\fR
	The \fB\-async\fR option will cause the client socket to be connected
	asynchronously. This means that the socket will be created immediately but
	may not yet be connected to the server, when the call to \fBsocket\fR
	returns. When a \fBgets\fR or \fBflush\fR is done on the socket before the
	connection attempt succeeds or fails, if the socket is in blocking mode, the
	operation will wait until the connection is completed or fails. If the
	socket is in nonblocking mode and a \fBgets\fR or \fBflush\fR is done on
	the socket before the connection attempt succeeds or fails, the operation
	returns immediately and \fBfblocked\fR on the socket returns 1.

	.SH "SERVER SOCKETS"
	.PP
	If the \fB\-server\fR option is specified then the new socket
	will be a server for the port given by \fIport\fR (either an integer
	or a service name, where supported and understood by the host
	operating system).
	Tcl will automatically accept connections to the given port.
	For each connection Tcl will create a new channel that may be used to
	communicate with the client. Tcl then invokes \fIcommand\fR
	with three additional arguments: the name of the new channel, the
	address, in network address notation, of the client's host, and
	the client's port number.
	.PP
	The following additional option may also be specified before \fIhost\fR:
	.TP
	\fB\-myaddr\fI addr\fR
	\fIAddr\fR gives the domain-style name or numerical IP address of
	the server-side network interface to use for the connection.
	This option may be useful if the server machine has multiple network
	interfaces. If the option is omitted then the server socket is bound
	to the special address INADDR_ANY so that it can accept connections from
	any interface.
	.PP
	Server channels cannot be used for input or output; their sole use is to
	accept new client connections. The channels created for each incoming
	client connection are opened for input and output. Closing the server
	channel shuts down the server so that no new connections will be
	accepted; however, existing connections will be unaffected.
	.PP
	Server sockets depend on the Tcl event mechanism to find out when
	new connections are opened. If the application doesn't enter the
	event loop, for example by invoking the \fBvwait\fR command or
	calling the C procedure \fBTcl_DoOneEvent\fR, then no connections
	will be accepted.
	.PP
	If \fIport\fR is specified as zero, the operating system will allocate
	an unused port for use as a server socket. The port number actually
	allocated my be retrieved from the created server socket using the
	\fBfconfigure\fR command to retrieve the \fB\-sockname\fR option as
	described below.

	.SH "CONFIGURATION OPTIONS"
	The \fBfconfigure\fR command can be used to query several readonly
	configuration options for socket channels:
	.TP
	\fB\-error\fR
	This option gets the current error status of the given socket. This
	is useful when you need to determine if an asynchronous connect
	operation succeeded. If there was an error, the error message is
	returned. If there was no error, an empty string is returned.
	.TP
	\fB\-sockname\fR
	This option returns a list of three elements, the address, the host name
	and the port number for the socket. If the host name cannot be computed,
	the second element is identical to the address, the first element of the
	list.
	.TP
	\fB\-peername\fR
	This option is not supported by server sockets. For client and accepted
	sockets, this option returns a list of three elements; these are the
	address, the host name and the port to which the peer socket is connected
	or bound. If the host name cannot be computed, the second element of the
	list is identical to the address, its first element.
	.PP

	.SH "SEE ALSO"
	flush(n), open(n), read(n)

	.SH KEYWORDS
	bind, channel, connection, domain name, host, network address, socket, tcp