/*
 * exportfs - Export a plan 9 name space across a network
 */
#include <u.h>
#include <libc.h>
#include <auth.h>
#include <fcall.h>
#include <libsec.h>

enum {
	Encnone,
	Encssl,
	Enctls,
};

#define DEBUG if(dbg)fprint
#define DFD 2

int	dbg;
int	netfd;
int	srvfd = -1;
int	nonone = 1;
char	*filterp;
char	*ealgs = "rc4_256 sha1";
char	*aanfilter = "/bin/aan";
int	encproto = Encnone;

static void	mksecret(char *, uchar *);
static int localread9pmsg(int, void *, uint, ulong *);
static char *anstring  = "tcp!*!0";
int	filter(int, char *);
void	fatal(char*, ...);
void copylog(int, int, char*);

int	export(int, char*, int);

void
usage(void)
{
	fprint(2, "usage:	%s [-ads] [-f dbgfile] [-m msize] [-r root] [-S srvfile] [-e 'crypt hash'] [-A announce-string]\n", argv0);
	fprint(2, "	%s -B address\n", argv0);
	fatal("usage");
}

void
main(int argc, char **argv)
{
	char buf[ERRMAX], ebuf[ERRMAX];
	int n, fd;
	char *dbfile, *srv, *file, *na, *nsfile, *keyspec;
	AuthInfo *ai;
	ulong initial;
	int negotiate;

	dbfile = "/tmp/exportdb";
	srv = nil;
	srvfd = -1;
	na = nil;
	nsfile = nil;
	keyspec = "";
	
	netfd = 0;
	dup(2, 1);

	negotiate = 1;
	ai = nil;
	fmtinstall('F', fcallfmt);
	fmtinstall('D', dirmodefmt);
	fmtinstall('H', encodefmt);
	
	ARGBEGIN{
	case 'a':
		/*
		 * We use p9any so we don't have to visit this code again, with the
		 * cost that this code is incompatible with the old world, which
		 * requires p9sk2. (The two differ in who talks first, so compatibility
		 * is awkward.)
		 */
		ai = auth_proxy(0, auth_getkey, "proto=p9any role=server %s", keyspec);
		if(ai == nil)
			fatal("auth_proxy: %r");
		if(nonone && strcmp(ai->cuid, "none") == 0)
			fatal("exportfs by none disallowed");
		if(auth_chuid(ai, nsfile) < 0)
			fatal("auth_chuid: %r");
		putenv("service", "exportfs");
		break;

	case 'k':
		keyspec = EARGF(usage());
		break;

	case 'e':
		ealgs = ARGF();
		if(ealgs == nil)
			usage();
		if(*ealgs == 0 || strcmp(ealgs, "clear") == 0)
			ealgs = nil;
		break;

	case 'S':
		if(srvfd != -1)
			usage();
		file = EARGF(usage());
		if((srvfd = open(file, ORDWR)) < 0)
			sysfatal("open '%s': %r", file);
		break;

	case 'd':
		dbg++;
		break;

	case 'f':
		dbfile = EARGF(usage());
		break;

	case 'n':
		nonone = 0;
		break;

	case 'N':
		nsfile = EARGF(usage());
		break;

	case 'r':
		srv = EARGF(usage());
		break;

	case 's':
		srv = "/";
		break;

	case 'A':
		anstring = EARGF(usage());
		break;

	case 'Z':
		negotiate = 0;
		break;

	default:
		usage();
	}ARGEND
	USED(argc, argv);

	if(na){
		if(srv == nil)
			sysfatal("-B requires -s");

		if((fd = dial(netmkaddr(na, 0, "importfs"), 0, 0, 0)) < 0)
			sysfatal("can't dial %s: %r", na);
	
		ai = auth_proxy(fd, auth_getkey, "proto=p9any role=client %s", keyspec);
		if(ai == nil)
			sysfatal("%r: %s", na);

		dup(fd, 0);
		dup(fd, 1);
		close(fd);
	}

	if(dbg){
		n = create(dbfile, OWRITE|OTRUNC, 0666);
		dup(n, 2);
		dup(2, 1);
		if(n > 2)
			close(n);
	}
	
	if(srvfd >= 0 && srv){
		fprint(2, "exportfs: -S cannot be used with -r or -s\n");
		usage();
	}

	DEBUG(DFD, "exportfs: started\n");

	rfork(RFNOTEG);

	/*
	 * Get tree to serve from network connection,
	 * check we can get there and ack the connection
 	 */
	if(srvfd != -1) {
		/* do nothing */
	}
	else if(srv) {
		chdir(srv);
		DEBUG(DFD, "invoked as server for %s", srv);
		strncpy(buf, srv, sizeof buf);
	}
	else {
		buf[0] = 0;
		n = read(0, buf, sizeof(buf)-1);
		if(n < 0) {
			errstr(buf, sizeof buf);
			fprint(0, "read(0): %s", buf);
			DEBUG(DFD, "read(0): %s", buf);
			exits(buf);
		}
		buf[n] = 0;
		if(chdir(buf) < 0) {
			errstr(ebuf, sizeof ebuf);
			fprint(0, "chdir(%d:\"%s\"): %s", n, buf, ebuf);
			DEBUG(DFD, "chdir(%d:\"%s\"): %s", n, buf, ebuf);
			exits(ebuf);
		}
	}

	DEBUG(DFD, "exportfs: %s\n", buf);

	if(srv == nil && srvfd == -1 && write(0, "OK", 2) != 2)
		fatal("open ack write");

	if(!negotiate)
		goto serve;
		
	if(readn(netfd, &initial, sizeof(ulong)) < sizeof(ulong))
		fatal("can't read initial string: %r\n");

	if (strncmp((char *)&initial, "impo", sizeof(ulong)) != 0)
		fatal("cannot negotiate");

	{
		char buf[128], *p, *args[3];

		// New import.  Read import's parameters...
		initial = 0;

		p = buf;
		while (p - buf < sizeof buf) {
			if ((n = read(netfd, p, 1)) < 0)
				fatal("can't read impo arguments: %r\n");

			if (n == 0)
				fatal("connection closed while reading arguments\n");

			if (*p == '\n') 
				*p = '\0';
			if (*p++ == '\0')
				break;
		}
		
		if (tokenize(buf, args, nelem(args)) != 2)
			fatal("impo arguments invalid: impo%s...\n", buf);

		if (!strcmp(args[0], "aan"))
			filterp = aanfilter;
		else if (strcmp(args[0], "nofilter"))
			fatal("import filter argument unsupported: %s\n", args[0]);

		if (!strcmp(args[1], "ssl"))
			encproto = Encssl;
		else if (!strcmp(args[1], "tls"))
			encproto = Enctls;
		else if (strcmp(args[1], "clear"))
			fatal("import encryption proto unsupported: %s\n", args[1]);

		if (encproto == Enctls)
			sysfatal("%s: tls has not yet been implemented\n", argv[0]);
	}

	if (encproto != Encnone && ealgs && ai) {
		uchar key[16];
		uchar digest[SHA1dlen];
		char fromclientsecret[21];
		char fromserversecret[21];
		int i;

		memmove(key+4, ai->secret, ai->nsecret);

		/* exchange random numbers */
		srand(truerand());
		for(i = 0; i < 4; i++)
			key[i+12] = rand();

		if (initial) 
			fatal("Protocol botch: old import\n");
		if(readn(netfd, key, 4) != 4)
			fatal("can't read key part; %r\n");

		if(write(netfd, key+12, 4) != 4)
			fatal("can't write key part; %r\n");

		/* scramble into two secrets */
		sha1(key, sizeof(key), digest, nil);
		mksecret(fromclientsecret, digest);
		mksecret(fromserversecret, digest+10);

		if (filterp)
			netfd = filter(netfd, filterp);

		switch (encproto) {
		case Encssl:
			netfd = pushssl(netfd, ealgs, fromserversecret, 
						fromclientsecret, nil);
			break;
		case Enctls:
		default:
			fatal("Unsupported encryption protocol\n");
		}

		if(netfd < 0)
			fatal("can't establish ssl connection: %r");
	}
	else if (filterp) {
		if (initial) 
			fatal("Protocol botch: don't know how to deal with this\n");
		netfd = filter(netfd, filterp);
	}

serve:
	
	if(dbg){
		int p[2];
		
		pipe(p);
		switch(fork()){
		case -1:
			fatal("fork");
		case 0:
			close(p[0]);
			switch(fork()){
			case -1:
				fatal("fork");
			case 0:
				fprint(2, "%d: copylog\n", getpid());
				copylog(netfd, p[1], "");
				postnote(PNGROUP, getpid(), "die");
				break;
			default:
				fprint(2, "%d: copylog\n", getpid());
				copylog(p[1], netfd, "  ");
				postnote(PNGROUP, getpid(), "die");
				break;
			}
			_exits(nil);
		default:
			close(p[1]);
			close(netfd);
			netfd = p[0];
		}
	}		
	
	fprint(2, "%d: export\n", getpid());
	export(netfd, ".", 0);
	postnote(PNGROUP, getpid(), "die");
	fprint(2, "%d: export finished\n", getpid());
	fatal(nil);
}

void
copylog(int r, int w, char *prefix)
{
	int n;
	static uchar buf[16384], buf0[16384];
	Fcall f;
	vlong t;
	Tm *tm;
	
	for(;;){
		n = read9pmsg(r, buf, sizeof buf);
		if(n <= 0)
			break;
		memmove(buf0, buf, n);
		t = nsec();
		tm = localtime(t/1000000000);
		if(convM2S(buf0, n, &f) < 0){
			fprint(2, "%s%02d:%02d:%02d.%06d convM2S failed\n", 
				prefix, tm->hour, tm->min, tm->sec, 
				(int)((t/1000)%1000000));
			break;
		}
		fprint(2, "%s%02d:%02d:%02d.%06d %F\n", 
			prefix, tm->hour, tm->min, tm->sec, 
			(int)((t/1000)%1000000), &f);
		if(write(w, buf, n) < 0)
			break;
	}
}


void
fatal(char *s, ...)
{
	char buf[ERRMAX];
	va_list arg;

	if (s) {
		va_start(arg, s);
		vsnprint(buf, ERRMAX, s, arg);
		va_end(arg);
	}

	if (s) 
		sysfatal(buf);
	else
		exits(nil);
}

/* Network on fd1, mount driver on fd0 */
int
filter(int fd, char *cmd)
{
	int p[2], lfd, len, nb, argc;
	char newport[128], buf[128], devdir[40], *s, *file, *argv[16];

	// Get a free port and post it to the client.
	if (announce(anstring, devdir) < 0)
		sysfatal("filter: Cannot announce %s: %r\n", anstring);

	snprint(buf, sizeof(buf), "%s/local", devdir);
	buf[sizeof buf - 1] = '\0';
	if ((lfd = open(buf, OREAD)) < 0)
		sysfatal("filter: Cannot open %s: %r\n", buf);
	if ((len = read(lfd, newport, sizeof newport - 1)) < 0)
		sysfatal("filter: Cannot read %s: %r\n", buf);
	close(lfd);
	newport[len] = '\0';

	if ((s = strchr(newport, '\n')) != nil)
		*s = '\0';

	if ((nb = write(fd, newport, len)) < 0) 
		sysfatal("getport; cannot write port; %r");
	assert(nb == len);

	argc = tokenize(cmd, argv, nelem(argv)-2);
	if (argc == 0)
		sysfatal("filter: empty command");
	argv[argc++] = buf;
	argv[argc] = nil;
	file = argv[0];
	if (s = strrchr(argv[0], '/'))
		argv[0] = s+1;

	if(pipe(p) < 0)
		fatal("pipe");

	switch(rfork(RFNOWAIT|RFPROC|RFFDG)) {
	case -1:
		fatal("rfork record module");
	case 0:
		if (dup(p[0], 1) < 0)
			fatal("filter: Cannot dup to 1; %r\n");
		if (dup(p[0], 0) < 0)
			fatal("filter: Cannot dup to 0; %r\n");
		close(p[0]);
		close(p[1]);
		exec(file, argv);
		fatal("exec record module");
	default:
		close(fd);
		close(p[0]);
	}
	return p[1];	
}

static void
mksecret(char *t, uchar *f)
{
	sprint(t, "%2.2ux%2.2ux%2.2ux%2.2ux%2.2ux%2.2ux%2.2ux%2.2ux%2.2ux%2.2ux",
		f[0], f[1], f[2], f[3], f[4], f[5], f[6], f[7], f[8], f[9]);
}