implement Dial; include "sys.m";	sys: Sys; include "dial.m"; ## the dialstring is of the form '[/net/]proto!dest'#dial(addr: string, local: string): ref Connection{	if(sys == nil)		sys = load Sys Sys->PATH;	(netdir, proto, rem) := dialparse(addr);	if(netdir != nil)		return csdial(netdir, proto, rem, local); 	c := csdial("/net", proto, rem, local);	if(c != nil)		return c;	err := sys->sprint("%r");	if(lookstr(err, "refused") >= 0)		return nil;	c = csdial("/net.alt", proto, rem, local);	if(c != nil)		return c;	# ignore the least precise one	alterr := sys->sprint("%r");	if(lookstr(alterr, "translate")>=0 || lookstr(alterr, "does not exist")>=0)		sys->werrstr(err);	else		sys->werrstr(alterr);	return nil;} ## ask the connection server to translate#csdial(netdir: string, proto: string, rem: string, local: string): ref Connection{	fd := sys->open(netdir+"/cs", Sys->ORDWR);	if(fd == nil){		# no connection server, don't translate		return call(netdir+"/"+proto+"/clone", rem, local);	} 	if(sys->fprint(fd, "%s!%s", proto, rem) < 0)		return  nil; 	# try each recipe until we get one that works	besterr, err: string;	sys->seek(fd, big 0, 0);	for(;;){		(clonefile, addr) := csread(fd);		if(clonefile == nil)			break;		c := call(redir(clonefile, netdir), addr, local);		if(c != nil)			return c;		err = sys->sprint("%r");		if(lookstr(err, "does not exist") < 0)			besterr = err;	}	if(besterr != nil)		sys->werrstr(besterr);	else		sys->werrstr(err);	return nil;} call(clonefile: string, dest: string, local: string): ref Connection{	(cfd, convdir) := clone(clonefile);	if(cfd == nil)		return nil; 	if(local != nil)		rv := sys->fprint(cfd, "connect %s %s", dest, local);	else		rv = sys->fprint(cfd, "connect %s", dest);	if(rv < 0)		return nil; 	fd := sys->open(convdir+"/data", Sys->ORDWR);	if(fd == nil)		return nil;	return ref Connection(fd, cfd, convdir);} clone(clonefile: string): (ref Sys->FD, string){	pdir := parent(clonefile);	if(pdir == nil){		sys->werrstr(sys->sprint("bad clone file name: %q", clonefile));		return (nil, nil);	}	cfd := sys->open(clonefile, Sys->ORDWR);	if(cfd == nil)		return (nil, nil);	lno := readchan(cfd);	if(lno == nil)		return (nil, nil);	return (cfd, pdir+"/"+lno);} readchan(cfd: ref Sys->FD): string{	buf := array[Sys->NAMEMAX] of byte;	n := sys->read(cfd, buf, len buf);	if(n < 0)		return nil;	if(n == 0){		sys->werrstr("empty clone file");		return nil;	}	return string int string buf[0: n];} redir(old: string, newdir: string): string{	# because cs is in a different name space, replace the mount point	# assumes the mount point is directory in root (eg, /net/proto/clone)	if(len old > 1 && old[0] == '/'){		p := lookc(old[1:], '/');		if(p >= 0)			return newdir+"/"+old[1+p+1:];	}	return newdir+"/"+old;} lookc(s: string, c: int): int{	for(i := 0; i < len s; i++)		if(s[i] == c)			return i;	return -1;} backc(s: string, i: int, c: int): int{	if(i >= len s)		return -1;	while(i >= 0 && s[i] != c)		i--;	return i;} lookstr(s: string, t: string): int{	lt := len t;	# we know it's not zeroSearch:	for(i := 0; i <= len s - lt; i++){		for(j := 0; j < lt; j++)			if(s[i+j] != t[j])				continue Search;		return i;	}	return -1;} ## [[/netdir/]proto!]remainder#dialparse(addr: string): (string, string, string){	p := lookc(addr, '!');	if(p < 0)		return (nil, "net", addr);	if(addr[0] != '/' && addr[0] != '#')		return (nil, addr[0: p], addr[p+1:]);	p2 := backc(addr, p, '/');	if(p2 <= 0)		return (addr[0: p], "net", addr[p+1:]);	# plan 9 returns proto ""	return (addr[0: p2], addr[p2+1: p], addr[p+1:]);} ## announce a network service#announce(addr: string): ref Connection{	if(sys == nil)		sys = load Sys Sys->PATH; 	(naddr, clonefile) := nettrans(addr);	if(naddr == nil)		return nil; 	(ctl, convdir) := clone(clonefile);	if(ctl == nil){		sys->werrstr(sys->sprint("announce %r"));		return nil;	} 	if(sys->fprint(ctl, "announce %s", naddr) < 0){		sys->werrstr(sys->sprint("announce writing %s: %r", clonefile));		return nil;	} 	return ref Connection(nil, ctl, convdir);} ## listen for an incoming call on announced connection#listen(ac: ref Connection): ref Connection{	if(sys == nil)		sys = load Sys Sys->PATH; 	pdir := parent(ac.dir);	# ac.dir should be /netdir/N	if(pdir == nil){		sys->werrstr(sys->sprint("listen directory format: %q", ac.dir));		return nil;	} 	ctl := sys->open(ac.dir+"/listen", Sys->ORDWR);	if(ctl == nil){		sys->werrstr(sys->sprint("listen opening %s: %r", ac.dir+"/listen"));		return nil;	} 	lno := readchan(ctl);	if(lno == nil){		sys->werrstr(sys->sprint("listen reading %s/listen: %r", ac.dir));		return nil;	}	return ref Connection(nil, ctl, pdir+"/"+lno); } ## translate an address [[/netdir/]proto!rem] using /netdir/cs# returning (newaddress, clonefile)#nettrans(addr: string): (string, string){	(netdir, proto, rem) := dialparse(addr);	if(proto == nil || proto == "net"){		sys->werrstr(sys->sprint("bad dial string: %s", addr));		return (nil, nil);	}	if(netdir == nil)		netdir = "/net"; 	# try to translate using connection server	fd := sys->open(netdir+"/cs", Sys->ORDWR);	if(fd == nil){		# use it untranslated		if(rem == nil){			sys->werrstr(sys->sprint("bad dial string: %s", addr));			return (nil, nil);		}		return (rem, netdir+"/"+proto+"/clone");	}	if(sys->fprint(fd, "%s!%s", proto, rem) < 0)		return (nil, nil);	sys->seek(fd, big 0, 0);	(clonefile, naddr) := csread(fd);	if(clonefile == nil)		return (nil, nil); 	return (naddr, redir(clonefile, netdir));} csread(fd: ref Sys->FD): (string, string){	buf := array[Sys->NAMEMAX] of byte;	n := sys->read(fd, buf, len buf);	if(n < 0)		return (nil, nil);	line := string buf[0: n];	p := lookc(line, ' ');	if(p < 0)		return (nil, nil);	if(p == 0){		sys->werrstr("cs: no translation");		return (nil, nil);	}	return (line[0:p], line[p+1:]);} ## accept a call, return an fd to the open data file#accept(c: ref Connection): ref Sys->FD{	if(sys == nil)		sys = load Sys Sys->PATH;	sys->fprint(c.cfd, "accept %s", lastname(c.dir));	# ignore return value, network might not need accepts	return sys->open(c.dir+"/data", Sys->ORDWR);} ## reject a call, tell device the reason for the rejection#reject(c: ref Connection, why: string): int{	if(sys == nil)		sys = load Sys Sys->PATH;	if(sys->fprint(c.cfd, "reject %s %q", lastname(c.dir), why) < 0)		return -1;	return 0;} lastname(dir: string): string{	p := backc(dir, len dir-1, '/');	if(p < 0)		return dir;	return dir[p+1:];	# N in /net/N} parent(dir: string): string{	p := backc(dir, len dir-1, '/');	if(p < 0)		return nil;	return dir[0: p];} netmkaddr(addr, net, svc: string): string{	if(sys == nil)		sys = load Sys Sys->PATH;	if(net == nil)		net = "net";	(n, nil) := sys->tokenize(addr, "!");	if(n <= 1){		if(svc== nil)			return sys->sprint("%s!%s", net, addr);		return sys->sprint("%s!%s!%s", net, addr, svc);	}	if(svc == nil || n > 2)		return addr;	return sys->sprint("%s!%s", addr, svc);} netinfo(c: ref Connection): ref Conninfo{	if(sys == nil)		sys = load Sys Sys->PATH;	if((dir := c.dir) == nil){		if(c.dfd == nil)			return nil;		dir = parent(sys->fd2path(c.dfd));		if(dir == nil)			return nil;	}	ci := ref Conninfo;	ci.dir = dir;	ci.root = parent(dir);	while((p := parent(ci.root)) != nil && p != "/")		ci.root = p;	(ok, d) := sys->stat(ci.dir);	if(ok >= 0)		ci.spec = sys->sprint("#%c%d", d.dtype, d.dev);	(ci.lsys, ci.lserv) = getendpoint(ci.dir, "local");	(ci.rsys, ci.rserv) = getendpoint(ci.dir, "remote");	p = parent(ci.dir);	if(p == nil)		return nil;	if(len p >= 5 && p[0:5] == "/net/")		p = p[5:];	ci.laddr = sys->sprint("%s!%s!%s", p, ci.lsys, ci.lserv);	ci.raddr = sys->sprint("%s!%s!%s", p, ci.rsys, ci.rserv);	return ci;} getendpoint(dir: string, file: string): (string, string){	fd := sys->open(dir+"/"+file, Sys->OREAD);	buf := array[128] of byte;	if(fd == nil || (n := sys->read(fd, buf, len buf)) <= 0)		return ("???", "???");	# compatible, but probably poor defaults	if(n > 0 && buf[n-1] == byte '\n')		n--;	s := string buf[0: n];	p := lookc(s, '!');	if(p < 0)		return (s, "???");	return (s[0:p], s[p+1:]);}