diff options
Diffstat (limited to 'tcl8.6/doc/socket.n')
-rw-r--r-- | tcl8.6/doc/socket.n | 235 |
1 files changed, 0 insertions, 235 deletions
diff --git a/tcl8.6/doc/socket.n b/tcl8.6/doc/socket.n deleted file mode 100644 index 3efdb37..0000000 --- a/tcl8.6/doc/socket.n +++ /dev/null @@ -1,235 +0,0 @@ -'\" -'\" 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. -'\" -.TH socket n 8.6 Tcl "Tcl Built-In Commands" -.so man.macros -.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 over IPv4 and IPv6; 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. -.PP -Note that the default encoding for \fIall\fR sockets is the system -encoding, as returned by \fBencoding system\fR. Most of the time, you -will need to use \fBchan configure\fR to alter this to something else, -such as \fIutf\-8\fR (ideal for communicating with other Tcl -processes) or \fIiso8859\-1\fR (useful for many network protocols, -especially the older ones). -.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.tcl.tk\fR or -a numerical IPv4 or IPv6 address such as \fB127.0.0.1\fR or \fB2001:DB8::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 -. -This 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. -.RS -.PP -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. Synchronous client sockets may -be switched (after they have connected) to operating in asynchronous -mode using: -.PP -.CS -\fBchan configure \fIchan \fB\-blocking 0\fR -.CE -.PP -See the \fBchan configure\fR command for more details. -.PP -The Tcl event loop should be running while an asynchronous connection -is in progress, because it may have to do several connection attempts -in the background. Running the event loop also allows you to set up a -writable channel event on the socket to get notified when the -asynchronous connection has succeeded or failed. See the \fBvwait\fR -and the \fBchan\fR commands for more details on the event loop and -channel events. -.PP -The \fBchan configure\fR option \fB-connecting\fR may be used to check if the connect is still running. To verify a successful connect, the option \fB-error\fR may be checked when \fB-connecting\fR returned 0. -.PP -Operation without the event queue requires at the moment calls to \fBchan configure\fR to advance the internal state machine. -.RE -.SH "SERVER SOCKETS" -.PP -If the \fB\-server\fR option is specified then the new socket will be -a server that listens on the given \fIport\fR (either an integer or a -service name, where supported and understood by the host operating -system; if \fIport\fR is zero, the operating system will allocate a -free port to the server socket which may be discovered by using -\fBchan configure\fR to read the \fB\-sockname\fR option). If the host -supports both, IPv4 and IPv6, the socket will listen on both address -families. 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 (properly -a command prefix list, see the \fBEXAMPLES\fR below) 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 \fIport\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 -wildcard address so that it can accept connections from any -interface. If \fIaddr\fR is a domain name that resolves to multiple IP -addresses that are available on the local machine, the socket will -listen on all of them. -.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 does not 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 may be retrieved from the created server socket using the -\fBchan configure\fR command to retrieve the \fB\-sockname\fR option as -described below. -.SH "CONFIGURATION OPTIONS" -.PP -The \fBchan configure\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. -.RS -.PP -Note that the error status is reset by the read operation; this mimics -the underlying getsockopt(SO_ERROR) call. -.RE -.TP -\fB\-sockname\fR -. -For client sockets (including the channels that get created when a -client connects to a server socket) 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. -.RS -.PP -For server sockets this option returns a list of a multiple of three -elements each group of which have the same meaning as described -above. The list contains more than one group when the server socket -was created without \fB\-myaddr\fR or with the argument to -\fB\-myaddr\fR being a domain name that resolves multiple IP addresses -that are local to the invoking host. -.RE -.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. -.TP -\fB\-connecting\fR -. -This option is not supported by server sockets. For client sockets, this option returns 1 if an asyncroneous connect is still in progress, 0 otherwise. -.PP -.SH "EXAMPLES" -.PP -Here is a very simple time server: -.PP -.CS -proc Server {startTime channel clientaddr clientport} { - puts "Connection from $clientaddr registered" - set now [clock seconds] - puts $channel [clock format $now] - puts $channel "[expr {$now - $startTime}] since start" - close $channel -} - -\fBsocket -server\fR [list Server [clock seconds]] 9900 -vwait forever -.CE -.PP -And here is the corresponding client to talk to the server and extract -some information: -.PP -.CS -set server localhost -set sockChan [\fBsocket\fR $server 9900] -gets $sockChan line1 -gets $sockChan line2 -close $sockChan -puts "The time on $server is $line1" -puts "That is [lindex $line2 0]s since the server started" -.CE -.SH "HISTORY" -Support for IPv6 was added in Tcl 8.6. -.SH "SEE ALSO" -chan(n), flush(n), open(n), read(n) -.SH KEYWORDS -asynchronous I/O, bind, channel, connection, domain name, host, network address, socket, tcp -'\" Local Variables: -'\" mode: nroff -'\" End: |