1 /*
2  * Copyright (c) 2021 Omar Polo <op@omarpolo.com>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #include "compat.h"
18 
19 #include <sys/stat.h>
20 
21 #include <dirent.h>
22 #include <endian.h>
23 #include <errno.h>
24 #include <fcntl.h>
25 #include <pwd.h>
26 #include <signal.h>
27 #include <stdlib.h>
28 #include <string.h>
29 #include <syslog.h>
30 #include <unistd.h>
31 
32 #include "client.h"
33 #include "kamid.h"
34 #include "log.h"
35 #include "sandbox.h"
36 #include "utils.h"
37 
38 /*
39  * XXX: atm is difficult to accept messages bigger than MAX_IMSGSIZE
40  * minus IMSG_HEADER_SIZE, we need something to split messages into
41  * chunks and receive them one by the other.
42  *
43  * CLIENT_MSIZE is thus the maximum message size we can handle now.
44  */
45 #define CLIENT_MSIZE (MAX_IMSGSIZE - IMSG_HEADER_SIZE)
46 
47 #define DEBUG_PACKETS 0
48 
49 /* straight outta /src/usr.bin/ssh/scp.c */
50 #define TYPE_OVERFLOW(type, val) \
51 	((sizeof(type) == 4 && (val) > INT32_MAX) || \
52 	 (sizeof(type) == 8 && (val) > INT64_MAX) || \
53 	 (sizeof(type) != 4 && sizeof(type) != 8))
54 
55 STAILQ_HEAD(dirhead, dir) dirs;
56 struct dir {
57 	int			 refcount;
58 	int			 fd;
59 	STAILQ_ENTRY(dir)	 entries;
60 };
61 
62 STAILQ_HEAD(fidhead, fid) fids;
63 struct fid {
64 	uint32_t		 fid;
65 
66 	char			 fpath[PATH_MAX];
67 
68 	/*
69 	 * the flags passed to open(2).  O_CLOEXEC means ORCLOSE, that
70 	 * is to unlink the file upon Tclunk.
71 	 */
72 	int			 iomode;
73 
74 	/*
75 	 * if fd is not -1 this fid was opened, fd represents its
76 	 * file descriptor and iomode the flags passed to open(2).
77 	 */
78 	int			 fd;
79 	DIR			*d;
80 	struct evbuffer		*evb;
81 
82 	/*
83 	 * expected offset for Tread against a directory.
84 	 */
85 	uint64_t		 offset;
86 
87 	struct qid		 qid;
88 	struct dir		*dir;
89 	STAILQ_ENTRY(fid)	 entries;
90 };
91 
92 static struct imsgev	*iev_listener;
93 static struct evbuffer	*evb;
94 static uint32_t		 peerid;
95 
96 static int		 handshaked;
97 uint32_t		 msize;
98 
99 static __dead void	client_shutdown(void);
100 static void		client_sig_handler(int, short, void *);
101 static void		client_dispatch_listener(int, short, void *);
102 static void		client_privdrop(const char *, const char *);
103 
104 static int		client_send_listener(int, const void *, uint16_t);
105 
106 static void		 qid_update_from_sb(struct qid *, struct stat *);
107 
108 static struct dir	*new_dir(int);
109 static struct dir	*dir_incref(struct dir *);
110 static void		 dir_decref(struct dir *);
111 
112 static struct fid	*new_fid(struct dir *, uint32_t, const char *, struct qid *);
113 static struct fid	*fid_by_id(uint32_t);
114 static void		 free_fid(struct fid *);
115 
116 static void		parse_message(const uint8_t *, size_t,
117 			    struct np_msg_header *, uint8_t **);
118 
119 static void		np_write16(struct evbuffer *, uint16_t);
120 static void		np_write32(struct evbuffer *, uint32_t);
121 static void		np_write64(struct evbuffer *, uint64_t);
122 static void		np_header(uint32_t, uint8_t, uint16_t);
123 static void		np_string(struct evbuffer *, uint16_t, const char *);
124 static void		np_qid(struct evbuffer *, struct qid *);
125 static void		do_send(void);
126 
127 static void		np_version(uint16_t, uint32_t, const char *);
128 static void		np_attach(uint16_t, struct qid *);
129 static void		np_clunk(uint16_t);
130 static void		np_flush(uint16_t);
131 static void		np_walk(uint16_t, int, struct qid *);
132 static void		np_open(uint16_t, struct qid *, uint32_t);
133 static void		np_create(uint16_t, struct qid *, uint32_t);
134 static void		np_read(uint16_t, uint32_t, void *);
135 static void		np_write(uint16_t, uint32_t);
136 static void		np_stat(uint16_t, uint32_t, void *);
137 static void		np_remove(uint16_t);
138 static void		np_error(uint16_t, const char *);
139 static void		np_errno(uint16_t);
140 
141 static int	np_read8(const char *, const char *, uint8_t *,
142 		    const uint8_t **, size_t *);
143 static int	np_read16(const char *, const char *, uint16_t *,
144 		    const uint8_t **, size_t *);
145 static int	np_read32(const char *, const char *, uint32_t *,
146 		    const uint8_t **, size_t *);
147 static int	np_read64(const char *, const char *, uint64_t *,
148 		    const uint8_t **, size_t *);
149 
150 #define READSTRERR	-1
151 #define READSTRTRUNC	-2
152 static int	np_readstr(const char *, const char *, char *, size_t,
153 		    const uint8_t **, size_t *);
154 
155 #define NPREAD8(f, dst, src, len)  np_read8(__func__, f, dst, src, len)
156 #define NPREAD16(f, dst, src, len) np_read16(__func__, f, dst, src, len)
157 #define NPREAD32(f, dst, src, len) np_read32(__func__, f, dst, src, len)
158 #define NPREAD64(f, dst, src, len) np_read64(__func__, f, dst, src, len)
159 
160 #define NPREADSTR(f, b, bl, src, len) np_readstr(__func__, f, b, bl, src, len)
161 
162 static void	tversion(struct np_msg_header *, const uint8_t *, size_t);
163 static void	tattach(struct np_msg_header *, const uint8_t *, size_t);
164 static void	tclunk(struct np_msg_header *, const uint8_t *, size_t);
165 static void	tflush(struct np_msg_header *, const uint8_t *, size_t);
166 static void	twalk(struct np_msg_header *, const uint8_t *, size_t);
167 static void	topen(struct np_msg_header *, const uint8_t *, size_t);
168 static void	tcreate(struct np_msg_header *, const uint8_t *, size_t);
169 static void	tread(struct np_msg_header *, const uint8_t *, size_t);
170 static void	twrite(struct np_msg_header *, const uint8_t *, size_t);
171 static void	tstat(struct np_msg_header *, const uint8_t *, size_t);
172 static void	tremove(struct np_msg_header *, const uint8_t *, size_t);
173 static void	handle_message(struct imsg *, size_t);
174 
175 __dead void
176 client(int debug, int verbose)
177 {
178 	struct event	ev_sigint, ev_sigterm;
179 
180 	log_init(debug, LOG_DAEMON);
181 	log_setverbose(verbose);
182 
183 	setproctitle("client");
184 	log_procinit("client");
185 
186 	log_debug("warming up");
187 
188 	event_init();
189 
190 	/* Setup signal handlers */
191 	signal_set(&ev_sigint, SIGINT, client_sig_handler, NULL);
192 	signal_set(&ev_sigterm, SIGTERM, client_sig_handler, NULL);
193 
194 	signal_add(&ev_sigint, NULL);
195 	signal_add(&ev_sigterm, NULL);
196 
197 	signal(SIGPIPE, SIG_IGN);
198 	signal(SIGHUP, SIG_IGN);
199 
200 	/* Setup pipe and event handler to the listener process */
201 	if ((iev_listener = malloc(sizeof(*iev_listener))) == NULL)
202 		fatal(NULL);
203 
204 	imsg_init(&iev_listener->ibuf, 3);
205 	iev_listener->handler = client_dispatch_listener;
206 
207 	/* Setup event handlers. */
208 	iev_listener->events = EV_READ;
209 	event_set(&iev_listener->ev, iev_listener->ibuf.fd,
210 	    iev_listener->events, iev_listener->handler, iev_listener);
211 	event_add(&iev_listener->ev, NULL);
212 
213 	event_dispatch();
214 	client_shutdown();
215 }
216 
217 static __dead void
218 client_shutdown(void)
219 {
220 	if (evb != NULL)
221 		evbuffer_free(evb);
222 
223 	msgbuf_clear(&iev_listener->ibuf.w);
224 	close(iev_listener->ibuf.fd);
225 
226         free(iev_listener);
227 
228 	log_debug("client exiting");
229 	exit(0);
230 }
231 
232 static void
233 client_sig_handler(int sig, short event, void *d)
234 {
235 	/*
236 	 * Normal signal handler rules don't apply because libevent
237 	 * decouples for us.
238 	 */
239 
240 	switch (sig) {
241 	case SIGINT:
242 	case SIGTERM:
243 		client_shutdown();
244 	default:
245 		fatalx("unexpected signal %d", sig);
246 	}
247 }
248 
249 #define AUTH_NONE 0
250 #define AUTH_USER 1
251 #define AUTH_DONE 2
252 
253 static void
254 client_dispatch_listener(int fd, short event, void *d)
255 {
256 	static int		 auth = AUTH_NONE;
257 	static char		 username[64] = {0};
258 	static char		 dir[PATH_MAX] = {0};
259 	struct imsg		 imsg;
260 	struct imsgev		*iev = d;
261 	struct imsgbuf		*ibuf;
262 	ssize_t			 n;
263 	int			 shut = 0;
264 
265 	ibuf = &iev->ibuf;
266 
267 	if (event & EV_READ) {
268 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
269 			fatal("imsg_read error");
270 		if (n == 0)	/* Connection closed */
271 			shut = 1;
272 	}
273 	if (event & EV_WRITE) {
274 		if ((n = msgbuf_write(&ibuf->w)) == -1 && errno != EAGAIN)
275 			fatal("msgbuf_write");
276 		if (n == 0)	/* Connection closed */
277 			shut = 1;
278 	}
279 
280 	for (;;) {
281 		if ((n = imsg_get(ibuf, &imsg)) == -1)
282 			fatal("%s: imsg_get error", __func__);
283 		if (n == 0)	/* No more messages. */
284 			break;
285 
286 		switch (imsg.hdr.type) {
287 		case IMSG_AUTH:
288 			peerid = imsg.hdr.peerid;
289 			if (auth)
290 				fatalx("%s: IMSG_AUTH already done", __func__);
291 			auth = AUTH_USER;
292 			((char *)imsg.data)[IMSG_DATA_SIZE(imsg)-1] = '\0';
293 			strlcpy(username, imsg.data, sizeof(username));
294 			break;
295 		case IMSG_AUTH_DIR:
296 			if (auth != AUTH_USER)
297 				fatalx("%s: IMSG_AUTH_DIR not after IMSG_AUTH",
298 				    __func__);
299 			auth = AUTH_DONE;
300 			((char *)imsg.data)[IMSG_DATA_SIZE(imsg)-1] = '\0';
301 			strlcpy(dir, imsg.data, sizeof(dir));
302 			client_privdrop(username, dir);
303 			memset(username, 0, sizeof(username));
304 			memset(dir, 0, sizeof(username));
305 			break;
306 		case IMSG_BUF:
307 			/* echo! */
308 			if (!auth)
309 				fatalx("%s: can't handle messages before"
310 				    " doing the auth", __func__);
311 			handle_message(&imsg, IMSG_DATA_SIZE(imsg));
312 			break;
313 		case IMSG_CONN_GONE:
314 			log_debug("closing");
315 			shut = 1;
316 			break;
317 		default:
318 			log_debug("%s: unexpected imsg %d",
319 			    __func__, imsg.hdr.type);
320 			break;
321 		}
322 		imsg_free(&imsg);
323 	}
324 
325 	if (!shut)
326 		imsg_event_add(iev);
327 	else {
328 		/* This pipe is dead.  Remove its event handler. */
329 		event_del(&iev->ev);
330 		log_debug("pipe closed, shutting down...");
331 		event_loopexit(NULL);
332 	}
333 }
334 
335 static void
336 client_privdrop(const char *username, const char *dir)
337 {
338 	struct passwd *pw;
339 
340 	setproctitle("client %s", username);
341 
342 	if ((pw = getpwnam(username)) == NULL)
343 		fatalx("getpwnam(%s) failed", username);
344 
345 	if (chroot(dir) == -1)
346 		fatal("chroot");
347 	if (chdir("/") == -1)
348 		fatal("chdir(\"/\")");
349 
350 	if (setgroups(1, &pw->pw_gid) ||
351 	    setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) ||
352 	    setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid))
353 		fatal("can't drop privileges");
354 
355 	sandbox_client();
356 	log_debug("client ready; user=%s dir=%s", username, dir);
357 
358 	if ((evb = evbuffer_new()) == NULL)
359 		fatal("evbuffer_new");
360 }
361 
362 static int
363 client_send_listener(int type, const void *data, uint16_t len)
364 {
365 	int ret;
366 
367 	if ((ret = imsg_compose(&iev_listener->ibuf, type, peerid, 0, -1,
368 	    data, len)) != -1)
369 		imsg_event_add(iev_listener);
370 
371 	return ret;
372 }
373 
374 /* set qid fields from sb */
375 static void
376 qid_update_from_sb(struct qid *qid, struct stat *sb)
377 {
378 	qid->path = sb->st_ino;
379 
380 	/*
381 	 * Theoretically (and hopefully!) this should be a 64 bit
382 	 * number.  Unfortunately, 9P uses 32 bit timestamps.
383 	 */
384 	qid->vers = sb->st_mtim.tv_sec;
385 
386 	if (S_ISREG(sb->st_mode))
387 		qid->type = QTFILE;
388 	else if (S_ISDIR(sb->st_mode))
389 		qid->type = QTDIR;
390 	else if (S_ISLNK(sb->st_mode))
391 		qid->type = QTSYMLINK;
392 }
393 
394 /* creates a qid given a fd */
395 static struct dir *
396 new_dir(int fd)
397 {
398 	struct dir	*dir;
399 
400 	if ((dir = calloc(1, sizeof(*dir))) == NULL)
401 		return NULL;
402 
403 	dir->fd = fd;
404 	STAILQ_INSERT_HEAD(&dirs, dir, entries);
405 	return dir;
406 }
407 
408 static struct dir *
409 dir_incref(struct dir *dir)
410 {
411 	dir->refcount++;
412 	return dir;
413 }
414 
415 static void
416 dir_decref(struct dir *dir)
417 {
418 	if (--dir->refcount > 0)
419 		return;
420 
421 	STAILQ_REMOVE(&dirs, dir, dir, entries);
422 
423 	close(dir->fd);
424 	free(dir);
425 }
426 
427 static struct fid *
428 new_fid(struct dir *dir, uint32_t fid, const char *path, struct qid *qid)
429 {
430 	struct fid	*f;
431 	struct qid	 q;
432 	struct stat	sb;
433 
434 	if (qid == NULL) {
435 		if (fstatat(dir->fd, path, &sb, 0)) {
436 			log_warn("fstatat(%s)", path);
437 			return NULL;
438 		}
439 		qid_update_from_sb(&q, &sb);
440 		qid = &q;
441 	}
442 
443 	if ((f = calloc(1, sizeof(*f))) == NULL)
444 		return NULL;
445 
446 	f->dir = dir_incref(dir);
447 	f->fid = fid;
448 	f->fd = -1;
449 
450 	strlcpy(f->fpath, path, sizeof(f->fpath));
451 
452 	memcpy(&f->qid, qid, sizeof(f->qid));
453 
454 	STAILQ_INSERT_HEAD(&fids, f, entries);
455 
456 	return f;
457 }
458 
459 static struct fid *
460 fid_by_id(uint32_t fid)
461 {
462 	struct fid	*f;
463 
464 	STAILQ_FOREACH(f, &fids, entries) {
465 		if (f->fid == fid)
466 			return f;
467 	}
468 
469 	return NULL;
470 }
471 
472 static void
473 free_fid(struct fid *f)
474 {
475 	int r;
476 
477 	if (f->fd != -1) {
478 		if (f->d != NULL)
479 			r = closedir(f->d);
480 		else
481 			r = close(f->fd);
482 
483 		if (r == -1)
484 			fatal("can't close fid %d", f->fid);
485 
486 		if (f->evb != NULL)
487 			evbuffer_free(f->evb);
488 
489 		/* try to honour ORCLOSE if requested */
490 		if (f->iomode & O_CLOEXEC)
491 			unlinkat(f->dir->fd, f->fpath, 0);
492 	}
493 
494 	dir_decref(f->dir);
495 
496 	STAILQ_REMOVE(&fids, f, fid, entries);
497 	free(f);
498 }
499 
500 static void
501 parse_message(const uint8_t *data, size_t len, struct np_msg_header *hdr,
502     uint8_t **cnt)
503 {
504 	size_t olen = len;
505 
506 	if (!NPREAD32("len", &hdr->len, &data, &len) ||
507 	    !NPREAD8("type", &hdr->type, &data, &len) ||
508 	    !NPREAD16("tag", &hdr->tag, &data, &len))
509 		goto err;
510 
511 	if (olen != hdr->len)
512 		goto err;
513 
514 	if (hdr->type < Tversion ||
515 	    hdr->type >= Tmax    ||
516 	    hdr->type == Terror  ||
517 	    (hdr->type & 0x1) != 0) /* cannot recv a R* */
518 		goto err;
519 
520 	hdr->tag = le32toh(hdr->tag);
521 
522 	*cnt = (uint8_t *)data;
523 	return;
524 
525 err:
526 	/* TODO: send a proper message to terminate the connection. */
527 	fatalx("got invalid message");
528 }
529 
530 static void
531 np_write16(struct evbuffer *e, uint16_t x)
532 {
533 	x = htole16(x);
534 	evbuffer_add(e, &x, sizeof(x));
535 }
536 
537 static void
538 np_write32(struct evbuffer *e, uint32_t x)
539 {
540 	x = htole32(x);
541 	evbuffer_add(e, &x, sizeof(x));
542 }
543 
544 static void
545 np_write64(struct evbuffer *e, uint64_t x)
546 {
547 	x = htole64(x);
548 	evbuffer_add(e, &x, sizeof(x));
549 }
550 
551 static void
552 np_writebuf(struct evbuffer *e, size_t len, void *data)
553 {
554 	evbuffer_add(e, data, len);
555 }
556 
557 static void
558 np_header(uint32_t len, uint8_t type, uint16_t tag)
559 {
560 	len += HEADERSIZE;
561 
562 	len = htole32(len);
563 	tag = htole16(tag);
564 
565 	evbuffer_add(evb, &len, sizeof(len));
566 	evbuffer_add(evb, &type, sizeof(type));
567 	evbuffer_add(evb, &tag, sizeof(tag));
568 }
569 
570 static void
571 np_string(struct evbuffer *e, uint16_t len, const char *str)
572 {
573 	uint16_t l = len;
574 
575 	len = htole16(len);
576 	evbuffer_add(e, &len, sizeof(len));
577 	evbuffer_add(e, str, l);
578 }
579 
580 static void
581 np_qid(struct evbuffer *e, struct qid *qid)
582 {
583 	uint64_t	path;
584 	uint32_t	vers;
585 
586 	path = htole64(qid->path);
587 	vers = htole32(qid->vers);
588 
589 	evbuffer_add(e, &qid->type, sizeof(qid->type));
590 	evbuffer_add(e, &vers, sizeof(vers));
591 	evbuffer_add(e, &path, sizeof(path));
592 }
593 
594 static void
595 do_send(void)
596 {
597 	size_t	 len;
598 	void	*data;
599 
600 	len = EVBUFFER_LENGTH(evb);
601 	data = EVBUFFER_DATA(evb);
602 
603 #if DEBUG_PACKETS
604 	hexdump("outgoing packet", data, len);
605 #endif
606 	client_send_listener(IMSG_BUF, data, len);
607 	evbuffer_drain(evb, len);
608 }
609 
610 static void
611 np_version(uint16_t tag, uint32_t msize, const char *version)
612 {
613 	uint16_t l;
614 
615 	l = strlen(version);
616 
617 	msize = htole32(msize);
618 
619 	np_header(sizeof(msize) + sizeof(l) + l, Rversion, tag);
620 	evbuffer_add(evb, &msize, sizeof(msize));
621 	np_string(evb, l, version);
622 	do_send();
623 }
624 
625 static void
626 np_attach(uint16_t tag, struct qid *qid)
627 {
628 	np_header(QIDSIZE, Rattach, tag);
629 	np_qid(evb, qid);
630 	do_send();
631 }
632 
633 static void
634 np_clunk(uint16_t tag)
635 {
636 	np_header(0, Rclunk, tag);
637 	do_send();
638 }
639 
640 static void
641 np_flush(uint16_t tag)
642 {
643 	np_header(0, Rflush, tag);
644 	do_send();
645 }
646 
647 static void
648 np_walk(uint16_t tag, int nwqid, struct qid *wqid)
649 {
650 	int i;
651 
652 	/* two bytes for the counter */
653 	np_header(2 + QIDSIZE * nwqid, Rwalk, tag);
654 	np_write16(evb, nwqid);
655 	for (i = 0; i < nwqid; ++i)
656 		np_qid(evb, wqid + i);
657 
658 	do_send();
659 }
660 
661 static void
662 np_open(uint16_t tag, struct qid *qid, uint32_t iounit)
663 {
664 	np_header(QIDSIZE + sizeof(iounit), Ropen, tag);
665 	np_qid(evb, qid);
666 	np_write32(evb, iounit);
667 	do_send();
668 }
669 
670 static void
671 np_create(uint16_t tag, struct qid *qid, uint32_t iounit)
672 {
673 	np_header(QIDSIZE + sizeof(iounit), Rcreate, tag);
674 	np_qid(evb, qid);
675 	np_write32(evb, iounit);
676 	do_send();
677 }
678 
679 static void
680 np_read(uint16_t tag, uint32_t count, void *data)
681 {
682 	np_header(sizeof(count) + count, Rread, tag);
683 	np_write32(evb, count);
684 	np_writebuf(evb, count, data);
685 	do_send();
686 }
687 
688 static void
689 np_write(uint16_t tag, uint32_t count)
690 {
691 	np_header(sizeof(count), Rwrite, tag);
692 	np_write32(evb, count);
693 	do_send();
694 }
695 
696 static void
697 np_stat(uint16_t tag, uint32_t count, void *data)
698 {
699 	np_header(count, Rstat, tag);
700 	np_writebuf(evb, count, data);
701 	do_send();
702 }
703 
704 static void
705 np_remove(uint16_t tag)
706 {
707 	np_header(0, Rremove, tag);
708 	do_send();
709 }
710 
711 static void
712 np_error(uint16_t tag, const char *errstr)
713 {
714 	uint16_t l;
715 
716 	l = strlen(errstr);
717 
718 	np_header(sizeof(l) + l, Rerror, tag);
719 	np_string(evb, l, errstr);
720 	do_send();
721 }
722 
723 static void
724 np_errno(uint16_t tag)
725 {
726 	int saved_errno;
727 	char buf[64];
728 
729 	saved_errno = errno;
730 
731 	strerror_r(errno, buf, sizeof(buf));
732 	np_error(tag, buf);
733 
734 	errno = saved_errno;
735 }
736 
737 static int
738 np_read8(const char *t, const char *f, uint8_t *dst, const uint8_t **src,
739     size_t *len)
740 {
741 	if (*len < sizeof(*dst)) {
742 		log_warnx("%s: wanted %zu bytes for the %s field but only "
743 		    "%zu are available.", t, sizeof(*dst), f, *len);
744 		return -1;
745 	}
746 
747 	memcpy(dst, *src, sizeof(*dst));
748 	*src += sizeof(*dst);
749 	*len -= sizeof(*dst);
750 
751 	return 1;
752 }
753 
754 static int
755 np_read16(const char *t, const char *f, uint16_t *dst, const uint8_t **src,
756     size_t *len)
757 {
758 	if (*len < sizeof(*dst)) {
759 		log_warnx("%s: wanted %zu bytes for the %s field but only "
760 		    "%zu are available.", t, sizeof(*dst), f, *len);
761 		return -1;
762 	}
763 
764 	memcpy(dst, *src, sizeof(*dst));
765 	*src += sizeof(*dst);
766 	*len -= sizeof(*dst);
767 	*dst = le16toh(*dst);
768 
769 	return 1;
770 }
771 
772 static int
773 np_read32(const char *t, const char *f, uint32_t *dst, const uint8_t **src,
774     size_t *len)
775 {
776 	if (*len < sizeof(*dst)) {
777 		log_warnx("%s: wanted %zu bytes for the %s field but only "
778 		    "%zu are available.", t, sizeof(*dst), f, *len);
779 		return -1;
780 	}
781 
782 	memcpy(dst, *src, sizeof(*dst));
783 	*src += sizeof(*dst);
784 	*len -= sizeof(*dst);
785 	*dst = le32toh(*dst);
786 
787 	return 1;
788 }
789 
790 static int
791 np_read64(const char *t, const char *f, uint64_t *dst, const uint8_t **src,
792     size_t *len)
793 {
794 	if (*len < sizeof(*dst)) {
795 		log_warnx("%s: wanted %zu bytes for the %s field but only "
796 		    "%zu are available.", t, sizeof(*dst), f, *len);
797 		return -1;
798 	}
799 
800 	memcpy(dst, *src, sizeof(*dst));
801 	*src += sizeof(*dst);
802 	*len -= sizeof(*dst);
803 	*dst = le64toh(*dst);
804 
805 	return 1;
806 }
807 
808 static int
809 np_readstr(const char *t, const char *f, char *res, size_t reslen,
810     const uint8_t **src, size_t *len)
811 {
812 	uint16_t	sl;
813 	char		buf[32];
814 
815 	strlcpy(buf, f, sizeof(buf));
816 	strlcat(buf, "-len", sizeof(buf));
817 
818 	if (!np_read16(t, buf, &sl, src, len))
819 		return READSTRERR;
820 
821 	if (*len < sl) {
822 		log_warnx("%s: wanted %d bytes for the %s field but only "
823 		    "%zu are available.", t, sl, f, *len);
824 		return READSTRERR;
825 	}
826 
827 	if (*len > reslen-1)
828 		return READSTRTRUNC;
829 
830 	memcpy(res, *src, sl);
831 	res[sl] = '\0';
832 	*src += sl;
833 	*len -= sl;
834 
835 	return 0;
836 }
837 
838 static void
839 tversion(struct np_msg_header *hdr, const uint8_t *data, size_t len)
840 {
841 	char *dot, version[32];
842 
843 	if (handshaked)
844 		goto err;
845 
846 	/* msize[4] version[s] */
847 	if (!NPREAD32("msize", &msize, &data, &len))
848 		goto err;
849 
850 	switch (NPREADSTR("version", version, sizeof(version), &data, &len)) {
851 	case READSTRERR:
852 		goto err;
853 	case READSTRTRUNC:
854 		log_warnx("9P version string too long, truncated");
855 		goto mismatch;
856 	}
857 
858 	if ((dot = strchr(version, '.')) != NULL)
859 		*dot = '\0';
860 
861 	if (strcmp(version, VERSION9P) != 0 ||
862 	    msize == 0)
863 		goto mismatch;
864 
865 	/* version matched */
866 	handshaked = 1;
867 	msize = MIN(msize, CLIENT_MSIZE);
868 	client_send_listener(IMSG_MSIZE, &msize, sizeof(msize));
869 	np_version(hdr->tag, msize, VERSION9P);
870 	return;
871 
872 mismatch:
873 	log_warnx("unknown 9P version string: \"%s\", want "VERSION9P,
874 	    version);
875 	np_version(hdr->tag, MSIZE9P, "unknown");
876 	return;
877 
878 err:
879 	client_send_listener(IMSG_CLOSE, NULL, 0);
880 	client_shutdown();
881 }
882 
883 static void
884 tattach(struct np_msg_header *hdr, const uint8_t *data, size_t len)
885 {
886 	struct dir	*dir;
887 	struct fid	*f;
888 	uint32_t	 fid, afid;
889 	int		 fd;
890 	char		 aname[PATH_MAX];
891 
892 	/* fid[4] afid[4] uname[s] aname[s] */
893 
894 	if (!NPREAD32("fid", &fid, &data, &len) ||
895 	    !NPREAD32("afid", &afid, &data, &len))
896 		goto err;
897 
898 	/* read the uname but don't actually use it */
899 	switch (NPREADSTR("uname", aname, sizeof(aname), &data, &len)) {
900 	case READSTRERR:
901 		goto err;
902 	case READSTRTRUNC:
903 		np_error(hdr->tag, "name too long");
904 		return;
905 	}
906 
907 	switch (NPREADSTR("aname", aname, sizeof(aname), &data, &len)) {
908 	case READSTRERR:
909 		goto err;
910 	case READSTRTRUNC:
911 		np_error(hdr->tag, "name too long");
912 		return;
913 	}
914 
915 	if (fid_by_id(fid) != NULL || afid != NOFID) {
916 		np_error(hdr->tag, "invalid fid or afid");
917 		return;
918 	}
919 
920 	if ((fd = open(aname, O_RDONLY|O_DIRECTORY)) == -1)
921 		goto fail;
922 
923 	if ((dir = new_dir(fd)) == NULL)
924 		goto fail;
925 
926 	log_debug("attached %s to %d", aname, fid);
927 
928 	if ((f = new_fid(dir, fid, aname, NULL)) == NULL) {
929 		dir_decref(dir);
930 		goto fail;
931 	}
932 
933 	np_attach(hdr->tag, &f->qid);
934 	return;
935 
936 fail:
937 	np_errno(hdr->tag);
938 	log_warn("failed to attach %s", aname);
939 	return;
940 
941 err:
942 	client_send_listener(IMSG_CLOSE, NULL, 0);
943 	client_shutdown();
944 }
945 
946 static void
947 tclunk(struct np_msg_header *hdr, const uint8_t *data, size_t len)
948 {
949 	struct fid	*f;
950 	uint32_t	 fid;
951 
952 	/* fid[4] */
953 	if (!NPREAD32("fid", &fid, &data, &len)) {
954 		client_send_listener(IMSG_CLOSE, NULL, 0);
955 		client_shutdown();
956 		return;
957 	}
958 
959 	if ((f = fid_by_id(fid)) == NULL) {
960 		np_error(hdr->tag, "invalid fid");
961 		return;
962 	}
963 
964 	free_fid(f);
965 	np_clunk(hdr->tag);
966 }
967 
968 static void
969 tflush(struct np_msg_header *hdr, const uint8_t *data, size_t len)
970 {
971 	uint16_t	oldtag;
972 
973 	/*
974 	 * We're doing only synchronous I/O.  Tflush is implemented
975 	 * only because it's illegal to reply with a Rerror.
976 	 */
977 
978 	/* oldtag[2] */
979 	if (len != sizeof(oldtag)) {
980 		log_warnx("Tflush with the wrong size: got %zu want %zu",
981 		    len, sizeof(oldtag));
982 		client_send_listener(IMSG_CLOSE, NULL, 0);
983 		client_shutdown();
984 		return;
985 	}
986 
987 	np_flush(hdr->tag);
988 }
989 
990 static void
991 twalk(struct np_msg_header *hdr, const uint8_t *data, size_t len)
992 {
993 	struct stat	 sb;
994 	struct dir	*dir;
995 	struct qid	 wqid[MAXWELEM] = {0};
996 	struct fid	*f, *nf;
997 	uint32_t	 fid, newfid;
998 	uint16_t	 nwname;
999 	int		 fd, oldfd, no, nwqid = 0;
1000 	char		 wnam[PATH_MAX];
1001 
1002 	if (!NPREAD32("fid", &fid, &data, &len)       ||
1003 	    !NPREAD32("newfid", &newfid, &data, &len) ||
1004 	    !NPREAD16("nwname", &nwname, &data, &len))
1005 		goto err;
1006 
1007 	if (nwname > MAXWELEM) {
1008 		log_warnx("Twalk: more than %d path elements: %d",
1009 		    MAXWELEM, nwname);
1010 		goto err;
1011 	}
1012 
1013 	if ((f = fid_by_id(fid)) == NULL) {
1014 		np_error(hdr->tag, "invalid fid");
1015 		return;
1016 	}
1017 
1018 	if (f->fd != -1) {
1019 		np_error(hdr->tag, "fid already opened for I/O");
1020 		return;
1021 	}
1022 
1023 	if (fid == newfid)
1024 		nf = f;
1025 	else if ((nf = fid_by_id(newfid)) != NULL) {
1026 		np_error(hdr->tag, "newfid already in use");
1027 		return;
1028 	} else
1029 		nf = NULL;
1030 
1031 	/* special case: fid duplication */
1032 	if (nwname == 0) {
1033 		/*
1034 		 * TODO: should we forbid fids duplication when fid ==
1035 		 * newfid?
1036 		 */
1037 		if (nf == NULL && 
1038 		    (nf = new_fid(f->dir, newfid, f->fpath, &f->qid)) == NULL)
1039 			fatal("new_fid duplication");
1040 
1041 		np_walk(hdr->tag, 0, NULL);
1042 		return;
1043 	}
1044 
1045 	if (!(f->qid.type & QTDIR)) {
1046 		np_error(hdr->tag, "fid doesn't represent a directory");
1047 		return;
1048 	}
1049 
1050 	oldfd = f->dir->fd;
1051 
1052 	for (nwqid = 0; nwqid < nwname; nwqid++) {
1053 		switch (NPREADSTR("wname", wnam, sizeof(wnam), &data, &len)) {
1054 		case READSTRERR:
1055 			goto err;
1056 		case READSTRTRUNC:
1057 			np_error(hdr->tag, "wname too long");
1058 			return;
1059 		}
1060 
1061 		if (*wnam == '\0' ||
1062 		    strchr(wnam, '/') != NULL ||
1063 		    !strcmp(wnam, ".")) {
1064 			errno = EINVAL;
1065 			goto cantopen;
1066 		}
1067 
1068 		if ((fd = openat(oldfd, wnam, O_RDONLY|O_DIRECTORY)) == -1 &&
1069 		    errno != ENOTDIR)
1070 			goto cantopen;
1071 
1072 		if ((fd == -1 && fstatat(oldfd, wnam, &sb, 0) == -1) ||
1073 		    (fd != -1 && fstat(fd, &sb) == -1))
1074 			goto cantopen;
1075 
1076 		qid_update_from_sb(&wqid[nwqid], &sb);
1077 
1078 		/* reached a file but we still have other components */
1079 		if (fd == -1 && nwqid+1 < nwname)
1080 			goto cantopen;
1081 
1082 		/* reached the end and found a file */
1083 		if (fd == -1 && nwqid+1 == nwname)
1084 			continue;
1085 
1086 		if (oldfd != f->dir->fd)
1087 			close(oldfd);
1088 		oldfd = fd;
1089 	}
1090 
1091 	/* 
1092 	 * If fd is -1 we've reached a file, otherwise we've just
1093 	 * reached another directory.  We must pay attention to what
1094 	 * file descriptor we use to create the dir, because if we've
1095 	 * reached a file and oldfd is f->dir->fd then we *must* share
1096 	 * the same dir (it was a walk of one path from a directory to a
1097 	 * file, otherwise fun is bound to happen as soon as the client
1098      	 * closes the fid for the directory but keeps the one for the
1099 	 * file.
1100 	 */
1101 	if (fd == -1 && oldfd == f->dir->fd)
1102 		dir = f->dir;
1103 	else if (fd == -1)
1104 		dir = new_dir(oldfd);
1105 	else
1106 		dir = new_dir(fd);
1107 
1108 	if (dir == NULL)
1109 		fatal("new_dir");
1110 
1111 	if (nf == NULL) {
1112 		if ((nf = new_fid(dir, newfid, wnam, &wqid[nwqid-1])) == NULL)
1113 			fatal("new fid");
1114 	} else {
1115 		/* update the dir */
1116 		dir_decref(nf->dir);
1117 		nf->dir = dir_incref(dir);
1118 	}
1119 
1120 	np_walk(hdr->tag, nwqid, wqid);
1121 	return;
1122 
1123 cantopen:
1124 	if (oldfd != f->dir->fd)
1125 		close(oldfd);
1126 	no = errno;
1127 	if (nwqid == 0)
1128 		np_error(hdr->tag, strerror(no));
1129 	else
1130 		np_walk(hdr->tag, nwqid, wqid);
1131 	return;
1132 
1133 err:
1134 	client_send_listener(IMSG_CLOSE, NULL, 0);
1135 	client_shutdown();
1136 }
1137 
1138 static inline int
1139 npmode_to_unix(uint8_t mode, int *flags)
1140 {
1141 	switch (mode & 0x0F) {
1142 	case KOREAD:
1143 		*flags = O_RDONLY;
1144 		break;
1145 	case KOWRITE:
1146 		*flags = O_WRONLY;
1147 		break;
1148 	case KORDWR:
1149 		*flags = O_RDWR;
1150 		break;
1151 	case KOEXEC:
1152 		log_warnx("tried to open something with KOEXEC");
1153 		/* fallthrough */
1154 	default:
1155 		return -1;
1156 	}
1157 
1158 	if (mode & KOTRUNC)
1159 		*flags |= O_TRUNC;
1160 	if (mode & KORCLOSE)
1161 		*flags |= O_CLOEXEC;
1162 
1163 	return 0;
1164 }
1165 
1166 static void
1167 topen(struct np_msg_header *hdr, const uint8_t *data, size_t len)
1168 {
1169 	struct stat	 sb;
1170 	struct qid	 qid;
1171 	struct fid	*f;
1172 	uint32_t	 fid;
1173 	uint8_t		 mode;
1174 	const char	*path;
1175 
1176 	/* fid[4] mode[1] */
1177 	if (!NPREAD32("fid", &fid, &data, &len) ||
1178 	    !NPREAD8("mode", &mode, &data, &len)) {
1179 		client_send_listener(IMSG_CLOSE, NULL, 0);
1180 		client_shutdown();
1181 		return;
1182 	}
1183 
1184 	if ((f = fid_by_id(fid)) == NULL || f->fd != -1) {
1185 		np_error(hdr->tag, "invalid fid");
1186 		return;
1187 	}
1188 
1189 	if (npmode_to_unix(mode, &f->iomode) == -1) {
1190 		np_error(hdr->tag, "invalid mode");
1191 		return;
1192 	}
1193 
1194 	path = f->fpath;
1195 	if (f->qid.type & QTDIR)
1196 		path = ".";
1197 
1198 	if ((f->fd = openat(f->dir->fd, path, f->iomode)) == -1) {
1199 		np_error(hdr->tag, strerror(errno));
1200 		return;
1201 	}
1202 
1203 	if (fstat(f->fd, &sb) == -1)
1204 		fatal("fstat");
1205 
1206 	if (S_ISDIR(sb.st_mode)) {
1207 		if ((f->d = fdopendir(f->fd)) == NULL) {
1208 			np_errno(hdr->tag);
1209 			close(f->fd);
1210 			f->fd = -1;
1211 			return;
1212 		}
1213 
1214 		if ((f->evb = evbuffer_new()) == NULL) {
1215 			np_errno(hdr->tag);
1216 			closedir(f->d);
1217 			f->d = NULL;
1218 			f->fd = -1;
1219 		}
1220 	}
1221 
1222 	f->offset = 0;
1223 
1224 	qid_update_from_sb(&qid, &sb);
1225 	np_open(hdr->tag, &qid, sb.st_blksize);
1226 }
1227 
1228 static void
1229 tcreate(struct np_msg_header *hdr, const uint8_t *data, size_t len)
1230 {
1231 	struct stat	 sb;
1232 	struct qid	 qid;
1233 	struct fid	*f;
1234 	uint32_t	 fid, perm;
1235 	uint8_t		 mode;
1236 	char		 name[PATH_MAX];
1237 
1238 	/* fid[4] name[s] perm[4] mode[1] */
1239 	if (!NPREAD32("fid", &fid, &data, &len))
1240 		goto err;
1241 	switch (NPREADSTR("name", name, sizeof(name), &data, &len)) {
1242 	case READSTRERR:
1243 		goto err;
1244 	case READSTRTRUNC:
1245 		np_error(hdr->tag, "name too long");
1246 		return;
1247 	}
1248 	if (!NPREAD32("perm", &perm, &data, &len) ||
1249 	    !NPREAD8("mode", &mode, &data, &len))
1250 		goto err;
1251 
1252 	if (!strcmp(name, ".") || !strcmp(name, "..") ||
1253 	    strchr(name, '/') != NULL) {
1254 		np_error(hdr->tag, "invalid name");
1255 		return;
1256 	}
1257 
1258 	if ((f = fid_by_id(fid)) == NULL || f->fd != -1) {
1259 		np_error(hdr->tag, "invalid fid");
1260 		return;
1261 	}
1262 
1263 	if (!(f->qid.type & QTDIR)) {
1264 		np_error(hdr->tag, "fid doesn't identify a directory");
1265 		return;
1266 	}
1267 
1268 	if (npmode_to_unix(mode, &f->iomode) == -1) {
1269 		np_error(hdr->tag, "invalid mode");
1270 		return;
1271 	}
1272 
1273 	if (f->iomode & O_RDONLY) {
1274 		np_error(hdr->tag, "can't create a read-only file");
1275 		return;
1276 	}
1277 
1278 	/* TODO: parse the mode */
1279 
1280 	if (perm & 0x80000000) {
1281 		/* create a directory */
1282 		f->fd = mkdirat(f->dir->fd, name, 0755);
1283 	} else {
1284 		/* create a file */
1285 		f->fd = openat(f->dir->fd, name, f->iomode | O_CREAT | O_TRUNC,
1286 		    0644);
1287 	}
1288 
1289 	if (f->fd == -1) {
1290 		np_errno(hdr->tag);
1291 		return;
1292 	}
1293 
1294 	if (fstat(f->fd, &sb) == -1)
1295 		fatal("fstat");
1296 
1297 	if (S_ISDIR(sb.st_mode)) {
1298 		if ((f->d = fdopendir(f->fd)) == NULL) {
1299 			np_errno(hdr->tag);
1300 			close(f->fd);
1301 			f->fd = -1;
1302 			return;
1303 		}
1304 
1305 		if ((f->evb = evbuffer_new()) == NULL) {
1306 			np_errno(hdr->tag);
1307 			closedir(f->d);
1308 			f->d = NULL;
1309 			f->fd = -1;
1310 		}
1311 	}
1312 
1313 	f->offset = 0;
1314 
1315 	qid_update_from_sb(&qid, &sb);
1316 	np_create(hdr->tag, &qid, sb.st_blksize);
1317 
1318 	return;
1319 
1320 err:
1321 	client_send_listener(IMSG_CLOSE, NULL, 0);
1322 	client_shutdown();
1323 }
1324 
1325 static inline void
1326 serialize_stat(const char *fname, struct stat *sb, struct evbuffer *evb)
1327 {
1328 	struct qid	 qid;
1329 	const char	*uid, *gid, *muid;
1330 	size_t		 tot;
1331 	uint16_t	 namlen, uidlen, gidlen, ulen;
1332 
1333 	qid_update_from_sb(&qid, sb);
1334 
1335 	/* TODO: fill these fields */
1336 	uid = "";
1337 	gid = "";
1338 	muid = "";
1339 
1340 	namlen = strlen(fname);
1341 	uidlen = strlen(uid);
1342 	gidlen = strlen(gid);
1343 	ulen = strlen(muid);
1344 
1345 	tot = NPSTATSIZ(namlen, uidlen, gidlen, ulen);
1346 	if (tot > UINT32_MAX) {
1347 		log_warnx("stat info for dir entry %s would overflow",
1348 		    fname);
1349 		return;
1350 	}
1351 
1352 	np_write16(evb, tot);			/*	size[2]		*/
1353 	np_write16(evb, sb->st_rdev);		/*	type[2]		*/
1354 	np_write32(evb, sb->st_dev);		/*	dev[4]		*/
1355 	np_qid(evb, &qid);			/*	qid[13]		*/
1356 
1357 	/* XXX: translate? */
1358 	np_write32(evb, sb->st_mode);		/*	mode[4]		*/
1359 
1360 	np_write32(evb, sb->st_atim.tv_sec);	/*	atime[4]	*/
1361 	np_write32(evb, sb->st_mtim.tv_sec);	/*	mtime[4]	*/
1362 	np_write64(evb, sb->st_size);		/*	length[8]	*/
1363 	np_string(evb, namlen, fname);		/*	name[s]		*/
1364 	np_string(evb, uidlen, uid);		/*	uid[s]		*/
1365 	np_string(evb, gidlen, gid);		/*	gid[s]		*/
1366 	np_string(evb, ulen, muid);		/*	muid[s]		*/
1367 }
1368 
1369 static void
1370 tread(struct np_msg_header *hdr, const uint8_t *data, size_t len)
1371 {
1372 	struct fid	*f;
1373 	ssize_t		 r;
1374 	uint64_t	 off;
1375 	uint32_t	 fid, count;
1376 	char		 buf[2048];
1377 
1378 	/* fid[4] offset[8] count[4] */
1379 	if (!NPREAD32("fid", &fid, &data, &len) ||
1380 	    !NPREAD64("offset", &off, &data, &len) ||
1381 	    !NPREAD32("count", &count, &data, &len)) {
1382 		client_send_listener(IMSG_CLOSE, NULL, 0);
1383 		client_shutdown();
1384 		return;
1385 	}
1386 
1387 	if ((f = fid_by_id(fid)) == NULL || f->fd == -1) {
1388 		np_error(hdr->tag, "invalid fid");
1389 		return;
1390 	}
1391 
1392 	if (TYPE_OVERFLOW(off_t, off)) {
1393 		log_warnx("unexpected off_t size");
1394 		np_error(hdr->tag, "invalid offset");
1395 		return;
1396 	}
1397 
1398 	if (f->d == NULL) {
1399 		/* read a file */
1400 		r = pread(f->fd, buf, sizeof(buf), (off_t)off);
1401 		if (r == -1)
1402 			np_errno(hdr->tag);
1403 		else
1404 			np_read(hdr->tag, r, buf);
1405 	} else {
1406 		if (off == 0 && f->offset != 0) {
1407 			rewinddir(f->d);
1408 			f->offset = 0;
1409 			evbuffer_drain(f->evb, EVBUFFER_LENGTH(f->evb));
1410 		}
1411 
1412 		if (off != f->offset) {
1413 			np_error(hdr->tag, "can't seek in directories");
1414 			return;
1415 		}
1416 
1417 		while (EVBUFFER_LENGTH(f->evb) < count) {
1418 			struct dirent *d;
1419 			struct stat sb;
1420 
1421 			if ((d = readdir(f->d)) == NULL)
1422 				break;
1423 			if (fstatat(f->fd, d->d_name, &sb, 0) == -1) {
1424 				warn("fstatat");
1425 				continue;
1426 			}
1427 			serialize_stat(d->d_name, &sb, f->evb);
1428 		}
1429 
1430 		count = MIN(count, EVBUFFER_LENGTH(f->evb));
1431 		np_read(hdr->tag, count, EVBUFFER_DATA(f->evb));
1432 		evbuffer_drain(f->evb, count);
1433 
1434 		f->offset += count;
1435 	}
1436 }
1437 
1438 static void
1439 twrite(struct np_msg_header *hdr, const uint8_t *data, size_t len)
1440 {
1441 	struct fid	*f;
1442 	ssize_t		 r;
1443 	uint64_t	 off;
1444 	uint32_t	 fid, count;
1445 
1446 	/* fid[4] offset[8] count[4] data[count] */
1447 	if (!NPREAD32("fid", &fid, &data, &len) ||
1448 	    !NPREAD64("off", &off, &data, &len) ||
1449 	    !NPREAD32("count", &count, &data, &len) ||
1450 	    len != count) {
1451 		client_send_listener(IMSG_CLOSE, NULL, 0);
1452 		client_shutdown();
1453 		return;
1454 	}
1455 
1456 	if ((f = fid_by_id(fid)) == NULL || f->fd == -1) {
1457 		np_error(hdr->tag, "invalid fid");
1458 		return;
1459 	}
1460 
1461 	if (!(f->iomode & O_WRONLY) &&
1462 	    !(f->iomode & O_RDWR)) {
1463 		np_error(hdr->tag, "fid not opened for writing");
1464 		return;
1465 	}
1466 
1467 	if (TYPE_OVERFLOW(off_t, off)) {
1468 		log_warnx("unexpected off_t size");
1469 		np_error(hdr->tag, "invalid offset");
1470 		return;
1471 	}
1472 
1473 	if ((r = pwrite(f->fd, data, len, off)) == -1)
1474 		np_errno(hdr->tag);
1475 	else
1476 		np_write(hdr->tag, r);
1477 }
1478 
1479 static void
1480 tstat(struct np_msg_header *hdr, const uint8_t *data, size_t len)
1481 {
1482 	struct evbuffer	*evb;
1483 	struct stat	 sb;
1484 	struct fid	*f;
1485 	int		 r;
1486 	uint32_t	 fid;
1487 
1488 	/* fid[4] */
1489 	if (!NPREAD32("fid", &fid, &data, &len)) {
1490 		client_send_listener(IMSG_CLOSE, NULL, 0);
1491 		client_shutdown();
1492 		return;
1493 	}
1494 
1495 	/*
1496 	 * plan9' stat(9P) is not clear on whether the stat is allowed
1497 	 * on opened fids or not.
1498 	 */
1499 	if ((f = fid_by_id(fid)) == NULL) {
1500 		np_error(hdr->tag, "invalid fid");
1501 		return;
1502 	}
1503 
1504 	if ((evb = evbuffer_new()) == NULL)
1505 		fatal("evbuffer_new");
1506 
1507 	if (f->fd != -1)
1508 		r = fstat(f->fd, &sb);
1509 	else
1510 		r = fstatat(f->dir->fd, f->fpath, &sb, 0);
1511 
1512 	if (r == -1) {
1513 		np_errno(hdr->tag);
1514 		evbuffer_free(evb);
1515 		return;
1516 	}
1517 
1518 	serialize_stat(f->fpath, &sb, evb);
1519 	np_stat(hdr->tag, EVBUFFER_LENGTH(evb), EVBUFFER_DATA(evb));
1520 	evbuffer_free(evb);
1521 }
1522 
1523 static void
1524 tremove(struct np_msg_header *hdr, const uint8_t *data, size_t len)
1525 {
1526 	struct fid	*f;
1527 	uint32_t	 fid;
1528 	int		 r;
1529 	char		 dirpath[PATH_MAX + 3];
1530 
1531 	/* fid[4] */
1532 	if (!NPREAD32("fid", &fid, &data, &len)) {
1533 		client_send_listener(IMSG_CLOSE, NULL, 0);
1534 		client_shutdown();
1535 		return;
1536 	}
1537 
1538 	if ((f = fid_by_id(fid)) == NULL) {
1539 		np_error(hdr->tag, "invalid fid");
1540 		return;
1541 	}
1542 
1543 	if (f->qid.type & QTDIR) { /* directory */
1544 		strlcpy(dirpath, "../", sizeof(dirpath));
1545 		strlcat(dirpath, f->fpath, sizeof(dirpath));
1546 		r = unlinkat(f->dir->fd, dirpath, AT_REMOVEDIR);
1547 	} else /* file */
1548 		r = unlinkat(f->dir->fd, f->fpath, 0);
1549 
1550 	if (r == -1)
1551 		np_errno(hdr->tag);
1552 	else
1553 		np_remove(hdr->tag);
1554 
1555 	free_fid(f);
1556 }
1557 
1558 static void
1559 handle_message(struct imsg *imsg, size_t len)
1560 {
1561 	struct msg {
1562 		uint8_t	 type;
1563 		void	(*fn)(struct np_msg_header *, const uint8_t *, size_t);
1564 	} msgs[] = {
1565 		{Tversion,	tversion},
1566 		{Tattach,	tattach},
1567 		{Tclunk,	tclunk},
1568 		{Tflush,	tflush},
1569 		{Twalk,		twalk},
1570 		{Topen,		topen},
1571 		{Tcreate,	tcreate},
1572 		{Tread,		tread},
1573 		{Twrite,	twrite},
1574 		{Tstat,		tstat},
1575 		{Tremove,	tremove},
1576 	};
1577 	struct np_msg_header	 hdr;
1578 	size_t			 i;
1579 	uint8_t			*data;
1580 
1581 #if DEBUG_PACKETS
1582 	hexdump("incoming packet", imsg->data, len);
1583 #endif
1584 
1585 	parse_message(imsg->data, len, &hdr, &data);
1586 	len -= HEADERSIZE;
1587 
1588 	log_debug("got request: len=%d type=%d[%s] tag=%d",
1589 	    hdr.len, hdr.type, pp_msg_type(hdr.type), hdr.tag);
1590 
1591 	if (!handshaked && hdr.type != Tversion) {
1592 		client_send_listener(IMSG_CLOSE, NULL, 0);
1593 		client_shutdown();
1594 		return;
1595 	}
1596 
1597 	for (i = 0; i < sizeof(msgs)/sizeof(msgs[0]); ++i) {
1598 		if (msgs[i].type != hdr.type)
1599 			continue;
1600 
1601 		msgs[i].fn(&hdr, data, len);
1602 		return;
1603 	}
1604 
1605 	np_error(hdr.tag, "Not supported.");
1606 }