/*  * This file is part of the UCB release of Plan 9. It is subject to the license * terms in the LICENSE file found in the top-level directory of this * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No * part of the UCB release of Plan 9, including this file, may be copied, * modified, propagated, or distributed except according to the terms contained * in the LICENSE file. */ #include <u.h>#include <libc.h>#include <ip.h> voidusage(void){	fprint(2, "usage: %s [-x netmtpt]\n", argv0);	exits("usage");} voidmain(int argc, char **argv){	int fd, cfd, n;	char buf[4096], data[128], devdir[40], net[32]; 	setnetmtpt(net, sizeof net, nil); 	ARGBEGIN{	case 'x':		setnetmtpt(net, sizeof net, EARGF(usage()));		break;	}ARGEND; 	sprint(data, "%s/udp!*!echo", net);	cfd = announce(data, devdir);	if(cfd < 0)		sysfatal("can't announce %s: %r", data);	if(fprint(cfd, "headers") < 0)		sysfatal("can't set header mode: %r"); 	sprint(data, "%s/data", devdir);	fd = open(data, ORDWR);	if(fd < 0)		sysfatal("open %s: %r", data);	while ((n = read(fd, buf, sizeof buf)) > 0)		write(fd, buf, n);	if (n < 0)		sysfatal("error reading: %r");	exits(0);}