'\"
'\" Generated from file 'udp\&.man' by tcllib/doctools with format 'nroff'
'\" Copyright (c) 1999-2000 Columbia University; all rights reserved
'\"
.TH "udp" n 1\&.0\&.14 udp "Tcl UDP extension"
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.BS
.SH NAME
udp \- Create UDP sockets in Tcl
.SH SYNOPSIS
package require \fBTcl 8\&.5-\fR
.sp
package require \fBudp 1\&.0\&.14\fR
.sp
\fBudp_open\fR ?\fIlocalport\fR? ?\fBreuse\fR? ?\fBipv6\fR?
.sp
\fBudp_conf\fR \fIchannel\fR \fIhost\fR \fIport\fR
.sp
\fBudp_conf\fR \fIchannel\fR \fI?optionName?\fR \fI?value?\fR \fI?optionName value \&.\&.\&.?\fR
.sp
\fBudp_peek\fR \fIchannel\fR ?\fIbuffersize\fR?
.sp
\fB::udp::build-info\fR
.sp
\fB::udp::getaddrinfo\fR \fB-hostname\fR \fIname\fR \fI?optionName value \&.\&.\&.?\fR
.sp
\fB::udp::getnameinfo\fR \fIaddress\fR \fB?ipv6?\fR
.sp
.BE
.SH DESCRIPTION
This package provides support for using UDP through Tcl\&. The package provides
a new channel type and attempts to permit the use of packet oriented UDP
over stream oriented Tcl channels\&. The package defined three commands but
\fBudp_conf\fR should be considered depreciated in favor of the standard
Tcl command \fBfconfigure\fR\&.
.SH COMMANDS
.TP
\fBudp_open\fR ?\fIlocalport\fR? ?\fBreuse\fR? ?\fBipv6\fR?
\fBudp_open\fR will open a UDP socket\&. If a \fIlocalport\fR is specified the UDP
socket will be opened on that port\&. Otherwise the system will choose a port
and the user can use the \fBudp_conf\fR command to obtain the port number
if required\&.
.sp
The following keywords can be used to specify options on the opened socket\&.
.RS
.TP
\fBreuse\fR
Using this keyword sets the SO_REUSEADDR socket option which permits multiple
sockets to be bound to the same address/port combination\&.
.TP
\fBipv6\fR
By default a IPv4 socket is created\&. When keyword \fBipv6\fR is specified, an IPv6
socket is opened\&.
.RE
.TP
\fBudp_conf\fR \fIchannel\fR \fIhost\fR \fIport\fR
\fIDeprecated\fR in favor of the standard Tcl \fBfconfigure\fR or
\fBchan configure\fR commands\&.
.sp
\fBudp_conf\fR in this configuration is used to specify the remote destination
for packets written to this \fIchannel\fR\&. You must call this command before
writing data to the UDP socket\&.
.TP
\fBudp_conf\fR \fIchannel\fR \fI?optionName?\fR \fI?value?\fR \fI?optionName value \&.\&.\&.?\fR
\fIDeprecated\fR in favor of the standard Tcl \fBfconfigure\fR or
\fBchan configure\fR commands\&.
.sp
In addition to being used to configure the remote host, the \fBudp_conf\fR
command is used to obtain information about the UDP socket\&. NOTE all these
options are now available using the standard Tcl \fBfconfigure\fR or
\fBchan configure\fR command\&.
.RS
.TP
\fB-myport\fR
Returns the local port number of the socket\&. Read-only option\&.
.TP
\fB-remote\fR \fI?address port?\fR
Specifies or returns the remote hostname and port number\&. Can also be set using
\fBudp_conf\fR \fIchannel\fR \fIhost\fR \fIport\fR\&.
.TP
\fB-peer\fR
Returns the remote hostname and port number for the packet most recently
received by this socket\&. Read-only option\&.
.TP
\fB-family\fR
Returns whether socket is configured for IPv4 or IPv6\&. Read-only option\&.
.TP
\fB-broadcast\fR \fI?boolean?\fR
Specifies or returns whether can listen and send on the broadcast address\&. For some systems
a flag must be set on the socket to use broadcast\&. This option is not permitted when
using IPv6, instead use multicast\&.
.TP
\fB-ttl\fR \fI?count?\fR
The time-to-live is given as the number of router hops the packet may do\&. For
multicast packets this is important in specifying the distribution of the
packet\&. The system default for multicast is 1 which restricts the packet
to the local subnet\&. To permit packets to pass routers, you must increase the
ttl\&. A value of 31 should keep it within a site, while 255 is global\&.
.TP
\fB-mcastadd\fR groupaddr
.TP
\fB-mcastadd\fR "groupaddr netwif"
.TP
\fB-mcastdrop\fR groupaddr
.TP
\fB-mcastdrop\fR "groupaddr netwif"
.TP
\fB-mcastgroups\fR
\fBtcludp\fR sockets can support IPv4 and IPv6 multicast operations\&. To receive
multicast packets the application has to notify the operating system that
it should join a particular multicast group\&. For IPv4 these are specified as addresses
in the range 224\&.0\&.0\&.0 to 239\&.255\&.255\&.255\&.
.sp
When specifying only the \fIgroupaddr\fR the system will determine the network interface to use\&.
Specifying the \fInetwif\fR will join a multicast group on a specific network interface\&.
This is useful on a multihomed system with multiple network interfaces\&.
On windows you must specify the network interface index\&. For other platforms the network
interface (e\&.g\&. 'eth0') name can be specified\&.
.sp
To view the current set of multicast groups for a channel use \fI-mcastgroups\fR
.TP
\fB-mcastif\fR
Returns which interface is used for outgoing multicast packets\&. UNIX only\&.
.TP
\fB-mcastloop\fR \fI?boolean?\fR
With multicast udp the system can choose to receive packets that it has sent
or it can drop them\&. This is known as multicast loopback and can be controlled
using this option\&. By default the value is true and your application will receive
its own transmissions\&.
.RE
.TP
\fBudp_peek\fR \fIchannel\fR ?\fIbuffersize\fR?
Examine a packet without removing it from the buffer\&. Option \fIbuffersize\fR specifies the
maximum buffer size\&. Value must be between 0 and 16\&.
.sp
This function is not available on windows\&.
.TP
\fB::udp::build-info\fR
Return information on the build environment\&.
.TP
\fB::udp::getaddrinfo\fR \fB-hostname\fR \fIname\fR \fI?optionName value \&.\&.\&.?\fR
Returns a list with info on the IP address matching the specified parameters\&.
Valid options are:
.RS
.TP
\fB-hostname\fR \fIname\fR
Specifies which IP address to use for lookup\&. Can use IP address or name\&. Required option\&.
.TP
\fB-port\fR \fInumber\fR
Specifies which port number to use for lookup\&.
.TP
\fB-service\fR \fIname\fR
Specifies which well-known service (i\&.e\&. http, https, etc\&.) to use for port in lookup\&.
.TP
\fB-ipv4\fR
Only return IP v4 addresses\&.
.TP
\fB-ipv6\fR
Only return IP v6 addresses\&.
.TP
\fB-server\fR
Only return services for which hostname is a server\&.
.TP
\fB-tcp\fR
Only return TCP services\&.
.TP
\fB-udp\fR
Only return UDP services\&.
.RE
.TP
\fB::udp::getnameinfo\fR \fIaddress\fR \fB?ipv6?\fR
\fB::udp::getnameinfo\fR will return the name(s) corresponding to IP
address \fIaddress\fR\&. With \fIipv6\fR, address is an IPv6 address\&.
.PP
.SH EXAMPLES
.PP
.CS


# Send data to a remote UDP socket
proc udp_puts {host port} {
    set s [udp_open]
    fconfigure $s -remote [list $host $port]
    puts $s "Hello, World"
    close $f
}

.CE
.CS


# A simple UDP server
package require udp

proc udpEventHandler {sock} {
    set pkt [read $sock]
    set peer [fconfigure $sock -peer]
    puts "$peer: [string length $pkt] {$pkt}"
    return
}

proc udp_listen {port} {
    set srv [udp_open $port]
    fconfigure $srv -buffering none -translation binary
    fileevent $srv readable [list ::udpEventHandler $srv]
    puts "Listening on udp port: [fconfigure $srv -myport]"
    return $srv
}

set sock [udp_listen 53530]
vwait forever
close $sock

.CE
.CS


# A multicast demo\&.
proc udpEvent {chan} {
    set data [read $chan]
    set peer [fconfigure $chan -peer]
    puts "$peer [string length $data] '$data'"
    if {[string match "QUIT*" $data]} {
        close $chan
        set ::forever 1
    }
    return
}

set group 224\&.5\&.1\&.21
set port  7771
set s [udp_open $port]
fconfigure $s -buffering none -blocking 0
fconfigure $s -mcastadd $group -remote [list $group $port]
fileevent $s readable [list udpEvent $s]
puts -nonewline $s "hello, world"
set ::forever 0
vwait ::forever
exit

.CE
.SH HISTORY
Some of the code in this extension is copied from Michael Miller's tcludp
package\&. (http://www\&.neosoft\&.com/tcl/ftparchive/sorted/comm/tcludp-1\&.0/)
Compared with Michael's UDP extension, this extension provides Windows
support and provides the ability of using 'gets/puts' to read/write
the socket\&. In addition, it provides more configuration ability\&.
.PP
Enhancements to support binary data and to setup the package for the Tcl
Extension Architecture by Pat Thoyts\&.
.PP
Support for IPv6 and allowing a multicast join on a specific network interface is added by Huub Eikens\&.
.SH "SEE ALSO"
socket
.SH KEYWORDS
I/O, IP Address, TclUDP, UDP, asynchronous I/O, bind, channel, connection, domain, host, name, network, network address, networking, socket, udp
.SH COPYRIGHT
.nf
Copyright (c) 1999-2000 Columbia University; all rights reserved

.fi
