#!/usr/local/bin/perl
;#
;# tcpreceive: read input from tcp port and output to stdout
;#
;# Copyright (c) 1991-1994 Kazumasa Utashiro <utashiro@sra.co.jp>
;# Software Research Associates, Inc., Japan
;# 1-1-1 Hirakawa-cho, Chiyoda-ku, Tokyo 102, Japan
;#
;;								$_=<<";#.";
;# Usage: tcpreceive [-p port] [-i userid] [client]
;#
;# Options:
;#	-p port		local port number (taken from system if not specified)
;#	-i userid	restrict remote user using ident protocol
;#	-d		debug option
;#	-h		show this message
;#
;#	client		specify remote host if necessary
;#.
;; ($usage = $_) =~ s/(^|\n);# ?/\1/g;
;; $rcsid = '$Id: tcpreceive,v 1.2 1994/04/27 07:47:00 utashiro Exp $'
;#
;#
;# DESCRIPTION
;#
;#	Tcpreceive opens port, wait for connection from remote host
;#	and prints incoming data to the standard output.  It works
;#	like a pipe across the network and useful when used with
;#	tcpconnect command.
;#
;#
;# Example:
;#
;#	On one machine:
;#		% tcpreceive | tar xf -
;#		Please connect to port=xxxx
;#
;#	On the other machine:
;#		% tar cf - . | tcpconnect client:xxxx
;#

;# require 'sys/socket.ph';
unless (do 'sys/socket.ph') {
    print STDERR "File sys/socket.ph is not found. Using default...\n";
    eval 'sub SOCK_STREAM {1;} sub AF_INET {2;} sub PF_INET { &AF_INET;}';
}

;#
;# &usage2opts: Generate getopts string from usage
;#
sub usage2opts {
    local($_, $opts) = shift;
    while (/(^|\n)\t-(\w)(\t|\s\s)?/g) {
	$opts .= $2 . ($3 ? '' : ':');
    }
    $opts;
}
require 'getopts.pl';
sub usage { print $usage, "\n$rcsid\n"; exit 1; }
&Getopts(&usage2opts($usage)) || &usage;
&usage if $opt_h;

$debug = $opt_d;
$silent = $opt_s;
$localport = $opt_p;
$userid = $opt_i;

$clientname = shift;

if ($userid) {
    require 'ident.pl';
    $ident'debug = $debug;
}

$sockaddr='S n a4 x8';
($name, $aliases, $TCP) = getprotobyname('tcp');

select(STDERR);

chop($localname = `hostname`);
($name, $aliases, $type, $len, $localaddr) = gethostbyname($localname);
if ($clientname) {
    $clientaddr = &getaddr($clientname) || die "Unknown client $clientname.\n";
}
$serverport = (getservbyname($serverport, 'tcp'))[2]
    unless $serverport =~ /^\d+$/;

$this = pack($sockaddr, &AF_INET, $localport, pack('N', 0));
socket(S, &PF_INET, &SOCK_STREAM, $TCP) || die "socket: $!\n";
bind(S, $this) || die "bind: $!\n";
listen(S, 1) || die "listen: $!\n";
$newport = (unpack($sockaddr, getsockname(S)))[1];

printf STDERR "Please connect to port=%d\n", $newport;

($addr = accept(NS, S)) || die "accept: $!\n";

($af, $peerport, $peeraddr) = unpack($sockaddr, $addr);
if ($clientaddr && $peeraddr ne $clientaddr) {
    printf STDERR "Host \"%s\" is not allowed!\n", &dotted($peeraddr);
    exit 1;
}
printf STDERR
    "Connection established with %s(%d)\n",
    &dotted($peeraddr), $peerport
    if $debug;

if ($userid) {
    $remoteuser = &ident(NS);
    if ($userid ne $remoteuser) {
	if ($remoteuser) {
	    printf STDERR "User \"%s\" is not allowed!\n", $remoteuser;
	} else {
	    printf STDERR "Can't ident remote user.\n";
	}
	exit 1;
    }
    printf STDERR "Remote user is \"%s\".\n", $remoteuser if $debug;
}

&forward(NS, STDOUT);

print STDERR "$0($$): exiting\n" if $debug;
exit 0;

sub forward {
    local($from, $to) = @_;
    eval "print $to \$_ while(read($from, \$_, 4096));";
    shutdown($from, 1); shutdown($to, 0);
}

sub getaddr {
    local($_) = @_;
    /^[0-9\.]+$/ ? pack("C4", split(/\./)) : (gethostbyname($_))[4];
}

sub dotted { join('.', unpack('C4', shift)); }