implement Virgild; include "sys.m";sys: Sys; include "draw.m"; include "ip.m"; Virgild: module{	init:	fn(ctxt: ref Draw->Context, argv: list of string);}; stderr: ref Sys->FD; Udphdrsize: con IP->Udphdrlen; init(nil: ref Draw->Context, nil: list of string){	sys = load Sys Sys->PATH; 	stderr = sys->fildes(2); 	sys->pctl(Sys->FORKNS|Sys->FORKFD, nil);	if(sys->chdir("/lib/ndb") < 0){		sys->fprint(stderr, "virgild: no database\n");		return;	} 	for(;;sys->sleep(10*1000)){		fd := openlisten();		if(fd == nil)			return; 		buf := array[512] of byte;		for(;;){			n := sys->read(fd, buf, len buf);			if(n <= Udphdrsize){				break;			}			if(n <= Udphdrsize+1)				continue; 			# dump any cruft after the question			for(i := Udphdrsize; i < n; i++){				c := int buf[i];				if(c == ' ' || c == 0 || c == '\n')					break;			} 			answer := query(string buf[Udphdrsize:i]);			if(answer == nil)				continue; 			# reply			r := array of byte answer;			if(len r > len buf - Udphdrsize)				continue;			buf[Udphdrsize:] = r;			sys->write(fd, buf, Udphdrsize+len r);		}		fd = nil;	}} openlisten(): ref Sys->FD{	(ok, c) := sys->announce("udp!*!virgil");	if(ok < 0){		sys->fprint(stderr, "virgild: can't open port: %r\n");		return nil;	} 	if(sys->fprint(c.cfd, "headers") <= 0){		sys->fprint(stderr, "virgild: can't set headers: %r\n");		return nil;	} 	c.dfd = sys->open(c.dir+"/data", Sys->ORDWR);	if(c.dfd == nil) {		sys->fprint(stderr, "virgild: can't open data file\n");		return nil;	}	return c.dfd;} ##  query is userid?question##  for now, we're ignoring userid#query(request: string): string{	(n, l) := sys->tokenize(request, "?");	if(n < 2){		sys->fprint(stderr, "virgild: bad request %s %d\n", request, n);		return nil;	} 	#	#  until we have something better, ask cs	#  to translate, make the request look cs-like	#	fd := sys->open("/net/cs", Sys->ORDWR);	if(fd == nil){		sys->fprint(stderr, "virgild: can't open /net/cs - %r\n");		return nil;	}	q := array of byte ("tcp!" + hd(tl l) + "!1000");	if(sys->write(fd, q, len q) < 0){		sys->fprint(stderr, "virgild: can't write /net/cs - %r: %s\n", string q);		return nil;	}	sys->seek(fd, big 0, 0);	buf := array[512-Udphdrsize-len request-1] of byte;	n = sys->read(fd, buf, len buf);	if(n <= 0){		sys->fprint(stderr, "virgild: can't read /net/cs - %r\n");		return nil;	} 	(nil, l) = sys->tokenize(string buf[0:n], " \t");	(nil, l) = sys->tokenize(hd(tl l), "!");	return request + "=" + hd l;}