implement Smtp; include "sys.m";	sys : Sys;include "bufio.m";	bufio : Bufio;include "smtp.m"; FD, Connection: import sys;Iobuf : import bufio; ibuf, obuf : ref Bufio->Iobuf;conn : int = 0;init : int = 0; rpid : int = -1;cread : chan of (int, string); DEBUG : con 0; open(server : string): (int, string){	s : string; 	if (!init) {		sys = load Sys Sys->PATH;		bufio = load Bufio Bufio->PATH;		init = 1;	}	if (conn)		return (-1, "connection is already open");	if (server == nil)		server = "$smtp";	(ok, c) := sys->dial ("tcp!" + server + "!25", nil);	if (ok < 0)		return (-1, "dialup failed");	ibuf = bufio->fopen(c.dfd, Bufio->OREAD);	obuf = bufio->fopen(c.dfd, Bufio->OWRITE);	if (ibuf == nil || obuf == nil)		return (-1, "failed to open bufio");	cread = chan of (int, string);	spawn mreader(cread);	(rpid, nil) = <- cread; 	(ok, s) = mread();	if (ok < 0)		return (-1, s);	conn = 1;	return (1, nil);} sendmail (fromwho : string, towho : list of string, cc : list of string, mlist: list of string): (int, string){	ok : int;	s, t, line : string; 	if (!conn)		return (-1, "connection is not open");	(ok, s) = mcmd("RSET");	if (ok < 0)		return (-1, s);	(user, dom) := split(fromwho, '@');	if (fromwho == nil || user == nil)		return (-1, "no 'from' name");	if (towho == nil)		return (-1, "no 'to' name");	if (dom == nil)		return (-1, "no domain name");	(ok, s) = mcmd("HELO " + dom);	if (ok < 0)		return (-1, s);	(ok, s) = mcmd("MAIL FROM:<" + fromwho + ">");	if (ok < 0)		return (-1, s);	all := concat(towho, cc);	t = nil;	for ( ; all != nil; all = tl all) {		(ok, s) = mcmd("RCPT TO:<" + hd all + ">");		if (ok < 0)			t += " " + s;	}	if (t != nil)		return (-1, t);	(ok, s) = mcmd("DATA");	if (ok < 0)		return (-1, s);	for ( ; mlist != nil; mlist = tl mlist) {		for (msg := hd mlist; msg != nil; ) {			(line, msg) = split(msg, '\n');	# BUG: too much copying for larger messages			if (putline(line) < 0)				return (-1, sys->sprint("write to server failed: %r"));		}	}	obuf.flush();	(ok, s) = mcmd(".");      	if (ok < 0)  		return (-1, s);  	return (1, nil);} putline(line: string): int{	ln := len line;	if (ln > 0 && line[ln-1] == '\r')		line = line[0:ln-1];	if (line != nil && line[0] == '.'){		if(obuf.putb(byte '.') < 0)			return -1;	}	if(line != nil && obuf.puts(line) < 0)		return -1;	return obuf.puts("\r\n");} close(): (int, string){	ok : int; 	if (!conn)		return (-1, "connection is not open");	ok = mwrite("QUIT");	kill(rpid);	ibuf.close();	obuf.close();	conn = 0;	if (ok < 0)		return (-1, "failed to close connection");	return (1, nil);} SLPTIME : con 100;MAXSLPTIME : con 10000; mread() : (int, string){	t := 0;	while (t < MAXSLPTIME) {		alt {			(ok, s) := <- cread =>				return (ok, s);			* =>				t += SLPTIME;				sys->sleep(SLPTIME);		}	}	kill(rpid);	return (-1, "smtp timed out\n");		} mreader(c : chan of (int, string)){	c <- = (sys->pctl(0, nil), nil);	for (;;) {		line := ibuf.gets('\n');		if (DEBUG)			sys->print("mread : %s", line);		if (line == nil) {			c <- = (-1, "could not read response from server");			continue;		}		l := len line;		if (line[l-1] == '\n')			l--;		if (line[l-1] == '\r')			l--;		if (l < 3) {			c <- = (-1, "short response from server");			continue;		}		if (l > 0 && (line[0] == '1' || line[0] == '2' || line[0] == '3')) {			c <- = (1, nil);			continue;		}		c <- = (-1, line[3:l]);	}} mwrite(s : string): int{	s += "\r\n";	if (DEBUG)		sys->print("mwrite : %s", s);	b := array of byte s;	l := len b;	nb := obuf.write(b, l);	obuf.flush();	if (nb != l)		return -1;	return 1;} mcmd(s : string) : (int, string){	ok : int;	r : string; 	ok = mwrite(s);	if (ok < 0)		return (-1, err(s) + " send failed");	(ok, r) = mread();	if (ok < 0)		return (-1, err(s) + " receive failed (" + r + ")");	return (1, nil);} split(s : string, c : int) : (string, string){	for (i := 0; i < len s; i++)		if (s[i] == c)			return (s[0:i], s[i+1:]);	return (s, nil);} concat(l1, l2 : list of string) : list of string{	ls : list of string; 	ls = nil;	for (l := l1; l != nil; l = tl l)		ls = hd l :: ls;	for (l = l2; l != nil; l = tl l)		ls = hd l :: ls;	return ls;} err(s : string) : string{	for (i := 0; i < len s; i++)		if (s[i] == ' ' || s[i] == ':')			return s[0:i];	return s;} kill(pid : int) : int{	if (pid < 0)		return 0;	fd := sys->open("#p/" + string pid + "/ctl", sys->OWRITE);	if (fd == nil || sys->fprint(fd, "kill") < 0)		return -1;	return 0;}