##       Software from the book "Inferno Programming with Limbo"#       published by John Wiley & Sons, January 2003.##       p. Stanley-Marbell <pip@gemusehaken.org>#implement StyxHTTPtunnel; include "sys.m";include "draw.m";include "string.m";include "shtun.m"; sys		: Sys;str 		: String; Connection 	: import Sys;export_pipe	: array of ref Sys->FD;StyxMAX		: con 29;  init(nil : ref Draw->Context, nil : list of string){	sys = load Sys Sys->PATH;	str = load String String->PATH;         sys->bind("#|", "/chan", sys->MBEFORE);	export_pipe = array [2] of ref Sys->FD;	sys->pipe(export_pipe); 	if (sys->export(export_pipe[0], sys->EXPASYNC))	{		sys->print("Error - Could not export : %r\n");                exit;	} 	(n, conn) := sys->announce("tcp!*!"+SRVPORT);	if (n < 0)	{		sys->print("StyxHTTPtunnel - announce failed : %r\n");		exit;	} 	while (1)	{		listen(conn);	}} listen(conn : Connection){	(ok, c) := sys->listen(conn);	if (ok < 0)	{		sys->print("StyxHTTPtunnel - listen failed : %r\n");		exit;	} 	spawn hdlrthread(c);} hdlrthread(conn : Connection){	#	At most, we have a full Styx message encap. in padding HTML	buf := array [2*Sys->ATOMICIO] of byte;	n : int = 0;  	#	The connections data file is not opened by default,	#	must explicitly do so to accept the new connection	rdfd := sys->open(conn.dir + "/data", Sys->OREAD);	wdfd := sys->open(conn.dir + "/data", Sys->OWRITE);	rfd := sys->open(conn.dir + "/remote", Sys->OREAD); 	n = sys->read(rfd, buf, len buf);	sys->print("\nStyxHTTPtunnel : Got new connection from %s",			string buf[:n]); 	n = sys->read(rdfd, buf, len buf);	if (n < 1)	{		sys->print("Received empty request, discarding...\n");		return;	} 	#	Get the request from the client and deliver it to the Export	(clientdatalen, clientdata) := requestdecode(buf[:n]);	if (int clientdata[0] > StyxMAX)	{		sys->print("Bad msgtype [%d] from client", int clientdata[0]);		return;	} 	if (sys->write(export_pipe[1], clientdata, clientdatalen) !=		clientdatalen)	{		sys->print("Could not write to export_pipe : %r");	} 	#	Get the response from the Export and deliver it to the client	n = sys->read(export_pipe[1], buf, len buf);	if (n < 1)	{		sys->print("Empty read from export pipe\n");		return;	} 	if (int buf[0] > StyxMAX)	{		sys->raise(sys->sprint(			"fail:Bad msgtype [%d] from Export",int buf[0]));	} 	(n, buf) = clientfmt(buf, n); 	if (sys->write(wdfd, buf[:n], n) != n)	{		sys->raise(sys->sprint("fail:Could not write to wfd : %r"));	}} clientfmt(buf : array of byte, size : int) : (int, array of byte){	a := StyxHTTPtunnel->REPLYHDPAD;	b := StyxHTTPtunnel->REPLYTLPAD; 	bytes := array [size+a+b] of byte;	numbytes := len bytes; 	bytes[0:] = array of byte "<HTML><!";	bytes[a-2] = byte (numbytes & 16rFF);	bytes[a-1] = byte ((numbytes >> 8) & 16rFF);	bytes[a:] = buf[:size];	bytes[a+size:] = array of byte "></HTML>\r\n"; 	return (numbytes, bytes);} requestdecode(body : array of byte) : (int, array of byte){	a := StyxHTTPtunnel->QUERYHDPAD;	b := StyxHTTPtunnel->QUERYTLPAD; 	return (len body - (a+b), body[a: len body - b]);}