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diff --git a/doc/socket.n b/doc/socket.n new file mode 100644 index 0000000..f766660 --- /dev/null +++ b/doc/socket.n @@ -0,0 +1,125 @@ +'\" +'\" Copyright (c) 1996 Sun Microsystems, Inc. +'\" +'\" See the file "license.terms" for information on usage and redistribution +'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. +'\" +'\" SCCS: @(#) socket.n 1.14 97/10/31 12:51:12 +.so man.macros +.TH socket n 7.5 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 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 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. +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. + +.SH CONFIGURATION OPTIONS +The \fBfconfigure\fR command can be used to query several readonly +configuration options for socket channels: +.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 |