| '\" |
| '\" 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 |
| .\} |
| .el \{\ |
| .br |
| .ie !"\\$2"" \{\ |
| \&\\$1 \\fI\\$2\\fP |
| .\} |
| .el \{\ |
| \&\\fI\\$1\\fP |
| .\} |
| .\} |
| .. |
| '\" # 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 |
| '\" # ^b = 1 |
| .de BS |
| .br |
| .mk ^y |
| .nr ^b 1u |
| .if n .nf |
| .if n .ti 0 |
| .if n \l'\\n(.lu\(ul' |
| .if n .fi |
| .. |
| '\" # BE - end boxed text (draw box now) |
| .de BE |
| .nf |
| .ti 0 |
| .mk ^t |
| .ie n \l'\\n(^lu\(ul' |
| .el \{\ |
| .\" Draw four-sided box normally, but don't draw top of |
| .\" box if the box started on an earlier page. |
| .ie !\\n(^b-1 \{\ |
| \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul' |
| .\} |
| .el \}\ |
| \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul' |
| .\} |
| .\} |
| .fi |
| .br |
| .nr ^b 0 |
| .. |
| '\" # VS - start vertical sidebar |
| '\" # ^Y = starting y location |
| '\" # ^v = 1 (for troff; for nroff this doesn't matter) |
| .de VS |
| .if !"\\$2"" .br |
| .mk ^Y |
| .ie n 'mc \s12\(br\s0 |
| .el .nr ^v 1u |
| .. |
| '\" # VE - end of vertical sidebar |
| .de VE |
| .ie n 'mc |
| .el \{\ |
| .ev 2 |
| .nf |
| .ti 0 |
| .mk ^t |
| \h'|\\n(^lu+3n'\L'|\\n(^Yu-1v\(bv'\v'\\n(^tu+1v-\\n(^Yu'\h'-|\\n(^lu+3n' |
| .sp -1 |
| .fi |
| .ev |
| .\} |
| .nr ^v 0 |
| .. |
| '\" # Special macro to handle page bottom: finish off current |
| '\" # box/sidebar if in box/sidebar mode, then invoked standard |
| '\" # page bottom macro. |
| .de ^B |
| .ev 2 |
| 'ti 0 |
| 'nf |
| .mk ^t |
| .if \\n(^b \{\ |
| .\" Draw three-sided box if this is the box's first page, |
| .\" draw two sides but no top otherwise. |
| .ie !\\n(^b-1 \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c |
| .el \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c |
| .\} |
| .if \\n(^v \{\ |
| .nr ^x \\n(^tu+1v-\\n(^Yu |
| \kx\h'-\\nxu'\h'|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'|0u'\c |
| .\} |
| .bp |
| 'fi |
| .ev |
| .if \\n(^b \{\ |
| .mk ^y |
| .nr ^b 2 |
| .\} |
| .if \\n(^v \{\ |
| .mk ^Y |
| .\} |
| .. |
| '\" # DS - begin display |
| .de DS |
| .RS |
| .nf |
| .sp |
| .. |
| '\" # DE - end display |
| .de DE |
| .fi |
| .RE |
| .sp |
| .. |
| '\" # SO - start of list of standard options |
| .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 |
| .. |
| '\" # CS - begin code excerpt |
| .de CS |
| .RS |
| .nf |
| .ta .25i .5i .75i 1i |
| .. |
| '\" # CE - end code excerpt |
| .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 |