1 /*
2  * Copyright (c) 2021, 2022 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 #include <sys/types.h>
21 #include <sys/uio.h>
22 
23 #include <dirent.h>
24 #include <endian.h>
25 #include <errno.h>
26 #include <fcntl.h>
27 #include <inttypes.h>
28 #include <libgen.h>
29 #include <pwd.h>
30 #include <signal.h>
31 #include <stdint.h>
32 #include <stdio.h>
33 #include <stdlib.h>
34 #include <string.h>
35 #include <syslog.h>
36 #include <unistd.h>
37 
38 #include "client.h"
39 #include "kami.h"
40 #include "kamid.h"
41 #include "log.h"
42 #include "sandbox.h"
43 #include "utils.h"
44 
45 /*
46  * XXX: atm is difficult to accept messages bigger than MAX_IMSGSIZE
47  * minus IMSG_HEADER_SIZE, we need something to split messages into
48  * chunks and receive them one by the other.
49  *
50  * CLIENT_MSIZE is thus the maximum message size we can handle now.
51  */
52 #define CLIENT_MSIZE (MAX_IMSGSIZE - IMSG_HEADER_SIZE)
53 
54 #define DEBUG_PACKETS 0
55 
56 /* straight outta /src/usr.bin/ssh/scp.c */
57 #define TYPE_OVERFLOW(type, val) \
58 	((sizeof(type) == 4 && (val) > INT32_MAX) || \
59 	 (sizeof(type) == 8 && (val) > INT64_MAX) || \
60 	 (sizeof(type) != 4 && sizeof(type) != 8))
61 
62 STAILQ_HEAD(dirhead, dir) dirs;
63 struct dir {
64 	int			 refcount;
65 	int			 fd;
66 	STAILQ_ENTRY(dir)	 entries;
67 };
68 
69 STAILQ_HEAD(fidhead, fid) fids;
70 struct fid {
71 	uint32_t		 fid;
72 
73 	char			 fname[NAME_MAX];
74 
75 	/*
76 	 * the flags passed to open(2).  O_CLOEXEC means ORCLOSE, that
77 	 * is to unlink the file upon Tclunk.
78 	 */
79 	int			 iomode;
80 
81 	/*
82 	 * if fd is not -1 this fid was opened, fd represents its
83 	 * file descriptor and iomode the flags passed to open(2).
84 	 */
85 	int			 fd;
86 	DIR			*d;
87 	struct evbuffer		*evb;
88 
89 	/*
90 	 * expected offset for Tread against a directory.
91 	 */
92 	uint64_t		 offset;
93 
94 	struct qid		 qid;
95 	struct dir		*dir;
96 	STAILQ_ENTRY(fid)	 entries;
97 };
98 
99 static struct imsgev	*iev_listener;
100 static struct evbuffer	*evb;
101 static uint32_t		 peerid;
102 
103 static int		 handshaked;
104 uint32_t		 msize;
105 
106 static __dead void	client_shutdown(void);
107 static void		client_sig_handler(int, short, void *);
108 static void		client_dispatch_listener(int, short, void *);
109 static void		client_privdrop(const char *, const char *);
110 
111 static int		client_send_listenerp(int, uint32_t, const void *, uint16_t);
112 static int		client_send_listener(int, const void *, uint16_t);
113 
114 static void		 qid_update_from_sb(struct qid *, struct stat *);
115 
116 static struct dir	*new_dir(int);
117 static struct dir	*dir_incref(struct dir *);
118 static void		 dir_decref(struct dir *);
119 
120 static struct fid	*new_fid(struct dir *, uint32_t, const char *, struct qid *);
121 static struct fid	*fid_by_id(uint32_t);
122 static void		 free_fid(struct fid *);
123 
124 static void		parse_message(const uint8_t *, size_t,
125 			    struct np_msg_header *, uint8_t **);
126 
127 static void		np_write16(struct evbuffer *, uint16_t);
128 static void		np_write32(struct evbuffer *, uint32_t);
129 static void		np_write64(struct evbuffer *, uint64_t);
130 static void		np_header(uint32_t, uint8_t, uint16_t);
131 static void		np_string(struct evbuffer *, uint16_t, const char *);
132 static void		np_qid(struct evbuffer *, struct qid *);
133 static void		do_send(void);
134 
135 static void		np_version(uint16_t, uint32_t, const char *);
136 static void		np_attach(uint16_t, struct qid *);
137 static void		np_clunk(uint16_t);
138 static void		np_flush(uint16_t);
139 static void		np_walk(uint16_t, int, struct qid *);
140 static void		np_open(uint16_t, struct qid *, uint32_t);
141 static void		np_create(uint16_t, struct qid *, uint32_t);
142 static void		np_read(uint16_t, uint32_t, void *);
143 static void		np_write(uint16_t, uint32_t);
144 static void		np_stat(uint16_t, uint32_t, void *);
145 static void		np_wstat(uint16_t);
146 static void		np_remove(uint16_t);
147 static void		np_error(uint16_t, const char *);
148 static void		np_errno(uint16_t);
149 
150 static int	np_read8(const char *, const char *, uint8_t *,
151 		    const uint8_t **, size_t *);
152 static int	np_read16(const char *, const char *, uint16_t *,
153 		    const uint8_t **, size_t *);
154 static int	np_read32(const char *, const char *, uint32_t *,
155 		    const uint8_t **, size_t *);
156 static int	np_read64(const char *, const char *, uint64_t *,
157 		    const uint8_t **, size_t *);
158 
159 #define READSTRERR	-1
160 #define READSTRTRUNC	-2
161 static int	np_readstr(const char *, const char *, char *, size_t,
162 		    const uint8_t **, size_t *);
163 
164 static int	np_readst(const char *, const char *, struct np_stat *,
165 		    char *, size_t, const uint8_t **, size_t *);
166 
167 #define NPREAD8(f, dst, src, len)  np_read8(__func__, f, dst, src, len)
168 #define NPREAD16(f, dst, src, len) np_read16(__func__, f, dst, src, len)
169 #define NPREAD32(f, dst, src, len) np_read32(__func__, f, dst, src, len)
170 #define NPREAD64(f, dst, src, len) np_read64(__func__, f, dst, src, len)
171 
172 #define NPREADSTR(f, b, bl, src, len) np_readstr(__func__, f, b, bl, src, len)
173 
174 #define NPREADST(f, dst, n, nl, src, len) np_readst(__func__, f, dst, n, nl, src, len)
175 
176 static void	tversion(struct np_msg_header *, const uint8_t *, size_t);
177 static void	tattach(struct np_msg_header *, const uint8_t *, size_t);
178 static void	tclunk(struct np_msg_header *, const uint8_t *, size_t);
179 static void	tflush(struct np_msg_header *, const uint8_t *, size_t);
180 static void	twalk(struct np_msg_header *, const uint8_t *, size_t);
181 static void	topen(struct np_msg_header *, const uint8_t *, size_t);
182 static void	tcreate(struct np_msg_header *, const uint8_t *, size_t);
183 static void	tread(struct np_msg_header *, const uint8_t *, size_t);
184 static void	twrite(struct np_msg_header *, const uint8_t *, size_t);
185 static void	tstat(struct np_msg_header *, const uint8_t *, size_t);
186 static void	twstat(struct np_msg_header *, const uint8_t *, size_t);
187 static void	tremove(struct np_msg_header *, const uint8_t *, size_t);
188 static void	handle_message(struct imsg *, size_t);
189 
190 __dead void
191 client(int debug, int verbose)
192 {
193 	struct event	ev_sigint, ev_sigterm;
194 
195 	log_init(debug, LOG_DAEMON);
196 	log_setverbose(verbose);
197 
198 	setproctitle("client");
199 	log_procinit("client");
200 
201 	log_debug("warming up");
202 
203 	event_init();
204 
205 	/* Setup signal handlers */
206 	signal_set(&ev_sigint, SIGINT, client_sig_handler, NULL);
207 	signal_set(&ev_sigterm, SIGTERM, client_sig_handler, NULL);
208 
209 	signal_add(&ev_sigint, NULL);
210 	signal_add(&ev_sigterm, NULL);
211 
212 	signal(SIGPIPE, SIG_IGN);
213 	signal(SIGHUP, SIG_IGN);
214 
215 	/* Setup pipe and event handler to the listener process */
216 	if ((iev_listener = malloc(sizeof(*iev_listener))) == NULL)
217 		fatal(NULL);
218 
219 	imsg_init(&iev_listener->ibuf, 3);
220 	iev_listener->handler = client_dispatch_listener;
221 
222 	/* Setup event handlers. */
223 	iev_listener->events = EV_READ;
224 	event_set(&iev_listener->ev, iev_listener->ibuf.fd,
225 	    iev_listener->events, iev_listener->handler, iev_listener);
226 	event_add(&iev_listener->ev, NULL);
227 
228 	event_dispatch();
229 	client_shutdown();
230 }
231 
232 static __dead void
233 client_shutdown(void)
234 {
235 	if (evb != NULL)
236 		evbuffer_free(evb);
237 
238 	msgbuf_clear(&iev_listener->ibuf.w);
239 	close(iev_listener->ibuf.fd);
240 
241         free(iev_listener);
242 
243 	log_debug("client exiting");
244 	exit(0);
245 }
246 
247 static void
248 client_sig_handler(int sig, short event, void *d)
249 {
250 	/*
251 	 * Normal signal handler rules don't apply because libevent
252 	 * decouples for us.
253 	 */
254 
255 	switch (sig) {
256 	case SIGINT:
257 	case SIGTERM:
258 		client_shutdown();
259 	default:
260 		fatalx("unexpected signal %d", sig);
261 	}
262 }
263 
264 static void
265 client_dispatch_listener(int fd, short event, void *d)
266 {
267 	static int		 auth = 0;
268 	struct kd_auth_proc	 rauth;
269 	struct kd_debug_info	 debug;
270 	struct fid		*f;
271 	struct imsg		 imsg;
272 	struct imsgev		*iev = d;
273 	struct imsgbuf		*ibuf;
274 	ssize_t			 n;
275 	int			 shut = 0;
276 
277 	ibuf = &iev->ibuf;
278 
279 	if (event & EV_READ) {
280 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
281 			fatal("imsg_read error");
282 		if (n == 0)	/* Connection closed */
283 			shut = 1;
284 	}
285 	if (event & EV_WRITE) {
286 		if ((n = msgbuf_write(&ibuf->w)) == -1 && errno != EAGAIN)
287 			fatal("msgbuf_write");
288 		if (n == 0)	/* Connection closed */
289 			shut = 1;
290 	}
291 
292 	for (;;) {
293 		if ((n = imsg_get(ibuf, &imsg)) == -1)
294 			fatal("%s: imsg_get error", __func__);
295 		if (n == 0)	/* No more messages. */
296 			break;
297 
298 		switch (imsg.hdr.type) {
299 		case IMSG_CTL_LOG_VERBOSE:
300 			if (IMSG_DATA_SIZE(imsg) != sizeof(verbose))
301 				fatalx("%s: IMSG_CTL_LOG_VERBOSE wrong size",
302 				    __func__);
303 			memcpy(&verbose, imsg.data, sizeof(verbose));
304 			log_setverbose(verbose);
305 			break;
306 		case IMSG_CTL_DEBUG:
307 			STAILQ_FOREACH(f, &fids, entries) {
308 				memset(&debug, 0, sizeof(debug));
309 				debug.fid = f->fid;
310 				strlcpy(debug.path, f->fname,
311 				    sizeof(debug.path));
312 				client_send_listenerp(IMSG_CTL_DEBUG_BACK,
313 				    imsg.hdr.peerid, &debug, sizeof(debug));
314 			}
315 			client_send_listenerp(IMSG_CTL_DEBUG_END,
316 			    imsg.hdr.peerid, NULL, 0);
317 			break;
318 		case IMSG_AUTH:
319 			peerid = imsg.hdr.peerid;
320 			if (auth)
321 				fatalx("%s: IMSG_AUTH already done", __func__);
322 			auth = 1;
323 
324 			if (IMSG_DATA_SIZE(imsg) != sizeof(rauth))
325 				fatalx("mismatching size for IMSG_AUTH");
326 			memcpy(&rauth, imsg.data, sizeof(rauth));
327 			if (rauth.uname[sizeof(rauth.uname)-1] != '\0' ||
328 			    rauth.dir[sizeof(rauth.dir)-1] != '\0')
329 				fatalx("IMSG_AUTH strings not NUL-terminated");
330 
331 			client_privdrop(rauth.uname, rauth.dir);
332 			explicit_bzero(&rauth, sizeof(rauth));
333 			break;
334 		case IMSG_BUF:
335 			if (!auth)
336 				fatalx("%s: can't handle messages before"
337 				    " doing the auth", __func__);
338 			handle_message(&imsg, IMSG_DATA_SIZE(imsg));
339 			break;
340 		case IMSG_CONN_GONE:
341 			log_debug("closing");
342 			shut = 1;
343 			break;
344 		default:
345 			log_debug("%s: unexpected imsg %d",
346 			    __func__, imsg.hdr.type);
347 			break;
348 		}
349 		imsg_free(&imsg);
350 	}
351 
352 	if (!shut)
353 		imsg_event_add(iev);
354 	else {
355 		/* This pipe is dead.  Remove its event handler. */
356 		event_del(&iev->ev);
357 		log_debug("pipe closed, shutting down...");
358 		event_loopexit(NULL);
359 	}
360 }
361 
362 static void
363 client_privdrop(const char *username, const char *dir)
364 {
365 	struct passwd *pw;
366 
367 	setproctitle("client %s", username);
368 
369 	if ((pw = getpwnam(username)) == NULL)
370 		fatalx("getpwnam(%s) failed", username);
371 
372 	if (chroot(dir) == -1)
373 		fatal("chroot");
374 	if (chdir("/") == -1)
375 		fatal("chdir(\"/\")");
376 
377 	if (setgroups(1, &pw->pw_gid) ||
378 	    setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) ||
379 	    setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid))
380 		fatal("can't drop privileges");
381 
382 	sandbox_client();
383 	log_debug("client ready; user=%s dir=%s", username, dir);
384 
385 	if ((evb = evbuffer_new()) == NULL)
386 		fatal("evbuffer_new");
387 }
388 
389 static int
390 client_send_listenerp(int type, uint32_t peerid, const void *data, uint16_t len)
391 {
392 	int ret;
393 
394 	if ((ret = imsg_compose(&iev_listener->ibuf, type, peerid, 0, -1,
395 	    data, len)) != -1)
396 		imsg_event_add(iev_listener);
397 
398 	return ret;
399 }
400 
401 static int
402 client_send_listener(int type, const void *data, uint16_t len)
403 {
404 	return client_send_listenerp(type, peerid, data, len);
405 }
406 
407 /* set qid fields from sb */
408 static void
409 qid_update_from_sb(struct qid *qid, struct stat *sb)
410 {
411 	qid->path = sb->st_ino;
412 
413 	/*
414 	 * Theoretically (and hopefully!) this should be a 64 bit
415 	 * number.  Unfortunately, 9P uses 32 bit timestamps.
416 	 */
417 	qid->vers = sb->st_mtim.tv_sec;
418 
419 	if (S_ISREG(sb->st_mode))
420 		qid->type = QTFILE;
421 	else if (S_ISDIR(sb->st_mode))
422 		qid->type = QTDIR;
423 	else if (S_ISLNK(sb->st_mode))
424 		qid->type = QTSYMLINK;
425 }
426 
427 /* creates a qid given a fd */
428 static struct dir *
429 new_dir(int fd)
430 {
431 	struct dir	*dir;
432 
433 	if ((dir = calloc(1, sizeof(*dir))) == NULL)
434 		return NULL;
435 
436 	dir->fd = fd;
437 	STAILQ_INSERT_HEAD(&dirs, dir, entries);
438 	return dir;
439 }
440 
441 static struct dir *
442 dir_incref(struct dir *dir)
443 {
444 	dir->refcount++;
445 	return dir;
446 }
447 
448 static void
449 dir_decref(struct dir *dir)
450 {
451 	if (--dir->refcount > 0)
452 		return;
453 
454 	STAILQ_REMOVE(&dirs, dir, dir, entries);
455 
456 	close(dir->fd);
457 	free(dir);
458 }
459 
460 static struct fid *
461 new_fid(struct dir *dir, uint32_t fid, const char *path, struct qid *qid)
462 {
463 	struct fid	*f;
464 	struct qid	 q;
465 	struct stat	sb;
466 
467 	if (qid == NULL) {
468 		if (fstatat(dir->fd, path, &sb, 0)) {
469 			log_warn("fstatat(%s)", path);
470 			return NULL;
471 		}
472 		qid_update_from_sb(&q, &sb);
473 		qid = &q;
474 	}
475 
476 	if ((f = calloc(1, sizeof(*f))) == NULL)
477 		return NULL;
478 
479 	f->dir = dir_incref(dir);
480 	f->fid = fid;
481 	f->fd = -1;
482 
483 	strlcpy(f->fname, path, sizeof(f->fname));
484 
485 	memcpy(&f->qid, qid, sizeof(f->qid));
486 
487 	STAILQ_INSERT_HEAD(&fids, f, entries);
488 
489 	return f;
490 }
491 
492 static struct fid *
493 fid_by_id(uint32_t fid)
494 {
495 	struct fid	*f;
496 
497 	STAILQ_FOREACH(f, &fids, entries) {
498 		if (f->fid == fid)
499 			return f;
500 	}
501 
502 	return NULL;
503 }
504 
505 static void
506 free_fid(struct fid *f)
507 {
508 	int r;
509 
510 	if (f->fd != -1) {
511 		if (f->d != NULL)
512 			r = closedir(f->d);
513 		else
514 			r = close(f->fd);
515 
516 		if (r == -1)
517 			fatal("can't close fid %d", f->fid);
518 
519 		if (f->evb != NULL)
520 			evbuffer_free(f->evb);
521 
522 		/* try to honour ORCLOSE if requested */
523 		if (f->iomode & O_CLOEXEC)
524 			unlinkat(f->dir->fd, f->fname, 0);
525 	}
526 
527 	dir_decref(f->dir);
528 
529 	STAILQ_REMOVE(&fids, f, fid, entries);
530 	free(f);
531 }
532 
533 static void
534 parse_message(const uint8_t *data, size_t len, struct np_msg_header *hdr,
535     uint8_t **cnt)
536 {
537 	size_t olen = len;
538 
539 	if (!NPREAD32("len", &hdr->len, &data, &len) ||
540 	    !NPREAD8("type", &hdr->type, &data, &len) ||
541 	    !NPREAD16("tag", &hdr->tag, &data, &len))
542 		goto err;
543 
544 	if (olen != hdr->len)
545 		goto err;
546 
547 	if (hdr->type < Tversion ||
548 	    hdr->type >= Tmax    ||
549 	    hdr->type == Terror  ||
550 	    (hdr->type & 0x1) != 0) /* cannot recv a R* */
551 		goto err;
552 
553 	hdr->tag = le32toh(hdr->tag);
554 
555 	*cnt = (uint8_t *)data;
556 	return;
557 
558 err:
559 	/* TODO: send a proper message to terminate the connection. */
560 	fatalx("got invalid message");
561 }
562 
563 static void
564 np_write16(struct evbuffer *e, uint16_t x)
565 {
566 	x = htole16(x);
567 	evbuffer_add(e, &x, sizeof(x));
568 }
569 
570 static void
571 np_write32(struct evbuffer *e, uint32_t x)
572 {
573 	x = htole32(x);
574 	evbuffer_add(e, &x, sizeof(x));
575 }
576 
577 static void
578 np_write64(struct evbuffer *e, uint64_t x)
579 {
580 	x = htole64(x);
581 	evbuffer_add(e, &x, sizeof(x));
582 }
583 
584 static void
585 np_writebuf(struct evbuffer *e, size_t len, void *data)
586 {
587 	evbuffer_add(e, data, len);
588 }
589 
590 static void
591 np_header(uint32_t len, uint8_t type, uint16_t tag)
592 {
593 	len += HEADERSIZE;
594 
595 	len = htole32(len);
596 	tag = htole16(tag);
597 
598 	evbuffer_add(evb, &len, sizeof(len));
599 	evbuffer_add(evb, &type, sizeof(type));
600 	evbuffer_add(evb, &tag, sizeof(tag));
601 }
602 
603 static void
604 np_string(struct evbuffer *e, uint16_t len, const char *str)
605 {
606 	uint16_t l = len;
607 
608 	len = htole16(len);
609 	evbuffer_add(e, &len, sizeof(len));
610 	evbuffer_add(e, str, l);
611 }
612 
613 static void
614 np_qid(struct evbuffer *e, struct qid *qid)
615 {
616 	uint64_t	path;
617 	uint32_t	vers;
618 
619 	path = htole64(qid->path);
620 	vers = htole32(qid->vers);
621 
622 	evbuffer_add(e, &qid->type, sizeof(qid->type));
623 	evbuffer_add(e, &vers, sizeof(vers));
624 	evbuffer_add(e, &path, sizeof(path));
625 }
626 
627 static void
628 do_send(void)
629 {
630 	size_t	 len;
631 	void	*data;
632 
633 	len = EVBUFFER_LENGTH(evb);
634 	data = EVBUFFER_DATA(evb);
635 
636 #if DEBUG_PACKETS
637 	hexdump("outgoing packet", data, len);
638 #endif
639 	client_send_listener(IMSG_BUF, data, len);
640 	evbuffer_drain(evb, len);
641 }
642 
643 static void
644 np_version(uint16_t tag, uint32_t msize, const char *version)
645 {
646 	uint16_t l;
647 
648 	l = strlen(version);
649 
650 	msize = htole32(msize);
651 
652 	np_header(sizeof(msize) + sizeof(l) + l, Rversion, tag);
653 	evbuffer_add(evb, &msize, sizeof(msize));
654 	np_string(evb, l, version);
655 	do_send();
656 }
657 
658 static void
659 np_attach(uint16_t tag, struct qid *qid)
660 {
661 	np_header(QIDSIZE, Rattach, tag);
662 	np_qid(evb, qid);
663 	do_send();
664 }
665 
666 static void
667 np_clunk(uint16_t tag)
668 {
669 	np_header(0, Rclunk, tag);
670 	do_send();
671 }
672 
673 static void
674 np_flush(uint16_t tag)
675 {
676 	np_header(0, Rflush, tag);
677 	do_send();
678 }
679 
680 static void
681 np_walk(uint16_t tag, int nwqid, struct qid *wqid)
682 {
683 	int i;
684 
685 	/* two bytes for the counter */
686 	np_header(2 + QIDSIZE * nwqid, Rwalk, tag);
687 	np_write16(evb, nwqid);
688 	for (i = 0; i < nwqid; ++i)
689 		np_qid(evb, wqid + i);
690 
691 	do_send();
692 }
693 
694 static void
695 np_open(uint16_t tag, struct qid *qid, uint32_t iounit)
696 {
697 	np_header(QIDSIZE + sizeof(iounit), Ropen, tag);
698 	np_qid(evb, qid);
699 	np_write32(evb, iounit);
700 	do_send();
701 }
702 
703 static void
704 np_create(uint16_t tag, struct qid *qid, uint32_t iounit)
705 {
706 	np_header(QIDSIZE + sizeof(iounit), Rcreate, tag);
707 	np_qid(evb, qid);
708 	np_write32(evb, iounit);
709 	do_send();
710 }
711 
712 static void
713 np_read(uint16_t tag, uint32_t count, void *data)
714 {
715 	if (sizeof(count) + count + HEADERSIZE >= msize) {
716 		np_error(tag, "Rread would overflow");
717 		return;
718 	}
719 
720 	np_header(sizeof(count) + count, Rread, tag);
721 	np_write32(evb, count);
722 	np_writebuf(evb, count, data);
723 	do_send();
724 }
725 
726 static void
727 np_write(uint16_t tag, uint32_t count)
728 {
729 	np_header(sizeof(count), Rwrite, tag);
730 	np_write32(evb, count);
731 	do_send();
732 }
733 
734 static void
735 np_stat(uint16_t tag, uint32_t count, void *data)
736 {
737 	if (sizeof(count) + count + HEADERSIZE >= msize) {
738 		np_error(tag, "Rstat would overflow");
739 		return;
740 	}
741 
742 	np_header(count, Rstat, tag);
743 	np_writebuf(evb, count, data);
744 	do_send();
745 }
746 
747 static void
748 np_wstat(uint16_t tag)
749 {
750 	np_header(0, Rwstat, tag);
751 	do_send();
752 }
753 
754 static void
755 np_remove(uint16_t tag)
756 {
757 	np_header(0, Rremove, tag);
758 	do_send();
759 }
760 
761 static void
762 np_error(uint16_t tag, const char *errstr)
763 {
764 	uint16_t l;
765 
766 	l = strlen(errstr);
767 
768 	np_header(sizeof(l) + l, Rerror, tag);
769 	np_string(evb, l, errstr);
770 	do_send();
771 }
772 
773 static void
774 np_errno(uint16_t tag)
775 {
776 	int saved_errno;
777 	char buf[NL_TEXTMAX] = {0};
778 
779 	saved_errno = errno;
780 
781 	strerror_r(errno, buf, sizeof(buf));
782 	np_error(tag, buf);
783 
784 	errno = saved_errno;
785 }
786 
787 static int
788 np_read8(const char *t, const char *f, uint8_t *dst, const uint8_t **src,
789     size_t *len)
790 {
791 	if (*len < sizeof(*dst)) {
792 		log_warnx("%s: wanted %zu bytes for the %s field but only "
793 		    "%zu are available.", t, sizeof(*dst), f, *len);
794 		return 0;
795 	}
796 
797 	memcpy(dst, *src, sizeof(*dst));
798 	*src += sizeof(*dst);
799 	*len -= sizeof(*dst);
800 
801 	return 1;
802 }
803 
804 static int
805 np_read16(const char *t, const char *f, uint16_t *dst, const uint8_t **src,
806     size_t *len)
807 {
808 	if (*len < sizeof(*dst)) {
809 		log_warnx("%s: wanted %zu bytes for the %s field but only "
810 		    "%zu are available.", t, sizeof(*dst), f, *len);
811 		return 0;
812 	}
813 
814 	memcpy(dst, *src, sizeof(*dst));
815 	*src += sizeof(*dst);
816 	*len -= sizeof(*dst);
817 	*dst = le16toh(*dst);
818 
819 	return 1;
820 }
821 
822 static int
823 np_read32(const char *t, const char *f, uint32_t *dst, const uint8_t **src,
824     size_t *len)
825 {
826 	if (*len < sizeof(*dst)) {
827 		log_warnx("%s: wanted %zu bytes for the %s field but only "
828 		    "%zu are available.", t, sizeof(*dst), f, *len);
829 		return 0;
830 	}
831 
832 	memcpy(dst, *src, sizeof(*dst));
833 	*src += sizeof(*dst);
834 	*len -= sizeof(*dst);
835 	*dst = le32toh(*dst);
836 
837 	return 1;
838 }
839 
840 static int
841 np_read64(const char *t, const char *f, uint64_t *dst, const uint8_t **src,
842     size_t *len)
843 {
844 	if (*len < sizeof(*dst)) {
845 		log_warnx("%s: wanted %zu bytes for the %s field but only "
846 		    "%zu are available.", t, sizeof(*dst), f, *len);
847 		return 0;
848 	}
849 
850 	memcpy(dst, *src, sizeof(*dst));
851 	*src += sizeof(*dst);
852 	*len -= sizeof(*dst);
853 	*dst = le64toh(*dst);
854 
855 	return 1;
856 }
857 
858 static int
859 np_readstr(const char *t, const char *f, char *res, size_t reslen,
860     const uint8_t **src, size_t *len)
861 {
862 	uint16_t	sl;
863 	char		buf[32];
864 
865 	strlcpy(buf, f, sizeof(buf));
866 	strlcat(buf, "-len", sizeof(buf));
867 
868 	if (!np_read16(t, buf, &sl, src, len))
869 		return READSTRERR;
870 
871 	if (*len < sl) {
872 		log_warnx("%s: wanted %d bytes for the %s field but only "
873 		    "%zu are available.", t, sl, f, *len);
874 		return READSTRERR;
875 	}
876 
877 	if (*len > reslen-1)
878 		return READSTRTRUNC;
879 
880 	memcpy(res, *src, sl);
881 	res[sl] = '\0';
882 	*src += sl;
883 	*len -= sl;
884 
885 	return 0;
886 }
887 
888 static int
889 np_readst(const char *t, const char *f, struct np_stat *st,
890     char *name, size_t namelen, const uint8_t **src, size_t *len)
891 {
892 	memset(st, 0, sizeof(*st));
893 
894 	if (!np_read16(t, "stat.size", &st->size, src, len) ||
895 	    !np_read16(t, "stat.type", &st->type, src, len) ||
896 	    !np_read32(t, "stat.dev", &st->dev, src, len) ||
897 	    !np_read64(t, "stat.qid.path", &st->qid.path, src, len) ||
898 	    !np_read32(t, "stat.qid.vers", &st->qid.vers, src, len) ||
899 	    !np_read8(t, "stat.qid.type", &st->qid.type, src, len) ||
900 	    !np_read32(t, "stat.mode", &st->mode, src, len) ||
901 	    !np_read32(t, "stat.atime", &st->atime, src, len) ||
902 	    !np_read32(t, "stat.mtime", &st->mtime, src, len) ||
903 	    !np_read64(t, "stat.length", &st->length, src, len))
904 		return READSTRERR;
905 
906 	/*
907 	 * ignore everything but the name, we don't support
908 	 * changing those fields anyway
909 	 */
910 	st->name = name;
911 	return np_readstr(t, "stat.name", name, namelen, src, len);
912 }
913 
914 static void
915 tversion(struct np_msg_header *hdr, const uint8_t *data, size_t len)
916 {
917 	char *dot, version[32];
918 
919 	if (handshaked)
920 		goto err;
921 
922 	/* msize[4] version[s] */
923 	if (!NPREAD32("msize", &msize, &data, &len))
924 		goto err;
925 
926 	switch (NPREADSTR("version", version, sizeof(version), &data, &len)) {
927 	case READSTRERR:
928 		goto err;
929 	case READSTRTRUNC:
930 		log_warnx("9P version string too long, truncated");
931 		goto mismatch;
932 	}
933 
934 	if (len != 0)
935 		goto err;
936 
937 	if ((dot = strchr(version, '.')) != NULL)
938 		*dot = '\0';
939 
940 	if (strcmp(version, VERSION9P) != 0 ||
941 	    msize == 0)
942 		goto mismatch;
943 
944 	/* version matched */
945 	handshaked = 1;
946 	msize = MIN(msize, CLIENT_MSIZE);
947 	client_send_listener(IMSG_MSIZE, &msize, sizeof(msize));
948 	np_version(hdr->tag, msize, VERSION9P);
949 	return;
950 
951 mismatch:
952 	log_warnx("unknown 9P version string: \"%s\", want "VERSION9P,
953 	    version);
954 	np_version(hdr->tag, MSIZE9P, "unknown");
955 	return;
956 
957 err:
958 	client_send_listener(IMSG_CLOSE, NULL, 0);
959 	client_shutdown();
960 }
961 
962 static void
963 tattach(struct np_msg_header *hdr, const uint8_t *data, size_t len)
964 {
965 	struct dir	*dir;
966 	struct fid	*f;
967 	uint32_t	 fid, afid;
968 	int		 fd;
969 	char		 aname[PATH_MAX];
970 
971 	/* fid[4] afid[4] uname[s] aname[s] */
972 
973 	if (!NPREAD32("fid", &fid, &data, &len) ||
974 	    !NPREAD32("afid", &afid, &data, &len))
975 		goto err;
976 
977 	/* read the uname but don't actually use it */
978 	switch (NPREADSTR("uname", aname, sizeof(aname), &data, &len)) {
979 	case READSTRERR:
980 		goto err;
981 	case READSTRTRUNC:
982 		np_error(hdr->tag, "name too long");
983 		return;
984 	}
985 
986 	switch (NPREADSTR("aname", aname, sizeof(aname), &data, &len)) {
987 	case READSTRERR:
988 		goto err;
989 	case READSTRTRUNC:
990 		np_error(hdr->tag, "name too long");
991 		return;
992 	}
993 
994 	if (len != 0)
995 		goto err;
996 
997 	if (fid_by_id(fid) != NULL || afid != NOFID) {
998 		np_error(hdr->tag, "invalid fid or afid");
999 		return;
1000 	}
1001 
1002 	if ((fd = open(aname, O_RDONLY|O_DIRECTORY)) == -1)
1003 		goto fail;
1004 
1005 	if ((dir = new_dir(fd)) == NULL)
1006 		goto fail;
1007 
1008 	log_debug("attached %s to %d", aname, fid);
1009 
1010 	if ((f = new_fid(dir, fid, aname, NULL)) == NULL) {
1011 		dir_decref(dir);
1012 		goto fail;
1013 	}
1014 
1015 	np_attach(hdr->tag, &f->qid);
1016 	return;
1017 
1018 fail:
1019 	np_errno(hdr->tag);
1020 	log_warn("failed to attach %s", aname);
1021 	return;
1022 
1023 err:
1024 	client_send_listener(IMSG_CLOSE, NULL, 0);
1025 	client_shutdown();
1026 }
1027 
1028 static void
1029 tclunk(struct np_msg_header *hdr, const uint8_t *data, size_t len)
1030 {
1031 	struct fid	*f;
1032 	uint32_t	 fid;
1033 
1034 	/* fid[4] */
1035 	if (!NPREAD32("fid", &fid, &data, &len) ||
1036 	    len != 0) {
1037 		client_send_listener(IMSG_CLOSE, NULL, 0);
1038 		client_shutdown();
1039 		return;
1040 	}
1041 
1042 	if ((f = fid_by_id(fid)) == NULL) {
1043 		np_error(hdr->tag, "invalid fid");
1044 		return;
1045 	}
1046 
1047 	free_fid(f);
1048 	np_clunk(hdr->tag);
1049 }
1050 
1051 static void
1052 tflush(struct np_msg_header *hdr, const uint8_t *data, size_t len)
1053 {
1054 	uint16_t	oldtag;
1055 
1056 	/*
1057 	 * We're doing only synchronous I/O.  Tflush is implemented
1058 	 * only because it's illegal to reply with a Rerror.
1059 	 */
1060 
1061 	/* oldtag[2] */
1062 	if (len != sizeof(oldtag)) {
1063 		log_warnx("Tflush with the wrong size: got %zu want %zu",
1064 		    len, sizeof(oldtag));
1065 		client_send_listener(IMSG_CLOSE, NULL, 0);
1066 		client_shutdown();
1067 		return;
1068 	}
1069 
1070 	np_flush(hdr->tag);
1071 }
1072 
1073 static void
1074 twalk(struct np_msg_header *hdr, const uint8_t *data, size_t len)
1075 {
1076 	struct stat	 sb;
1077 	struct dir	*dir;
1078 	struct qid	 wqid[MAXWELEM] = {0};
1079 	struct fid	*f, *nf;
1080 	uint32_t	 fid, newfid;
1081 	uint16_t	 nwname;
1082 	int		 fd, oldfd, no, nwqid = 0;
1083 	char		 wnam[PATH_MAX];
1084 
1085 	if (!NPREAD32("fid", &fid, &data, &len)       ||
1086 	    !NPREAD32("newfid", &newfid, &data, &len) ||
1087 	    !NPREAD16("nwname", &nwname, &data, &len))
1088 		goto err;
1089 
1090 	if (nwname > MAXWELEM) {
1091 		log_warnx("Twalk: more than %d path elements: %d",
1092 		    MAXWELEM, nwname);
1093 		goto err;
1094 	}
1095 
1096 	if ((f = fid_by_id(fid)) == NULL) {
1097 		np_error(hdr->tag, "invalid fid");
1098 		return;
1099 	}
1100 
1101 	if (f->fd != -1) {
1102 		np_error(hdr->tag, "fid already opened for I/O");
1103 		return;
1104 	}
1105 
1106 	if (fid == newfid)
1107 		nf = f;
1108 	else if ((nf = fid_by_id(newfid)) != NULL) {
1109 		np_error(hdr->tag, "newfid already in use");
1110 		return;
1111 	} else
1112 		nf = NULL;
1113 
1114 	/* special case: fid duplication */
1115 	if (nwname == 0) {
1116 		/*
1117 		 * TODO: should we forbid fids duplication when fid ==
1118 		 * newfid?
1119 		 */
1120 		if (nf == NULL &&
1121 		    (nf = new_fid(f->dir, newfid, f->fname, &f->qid)) == NULL)
1122 			fatal("new_fid duplication");
1123 
1124 		np_walk(hdr->tag, 0, NULL);
1125 		return;
1126 	}
1127 
1128 	if (!(f->qid.type & QTDIR)) {
1129 		np_error(hdr->tag, "fid doesn't represent a directory");
1130 		return;
1131 	}
1132 
1133 	oldfd = f->dir->fd;
1134 
1135 	for (nwqid = 0; nwqid < nwname; nwqid++) {
1136 		switch (NPREADSTR("wname", wnam, sizeof(wnam), &data, &len)) {
1137 		case READSTRERR:
1138 			goto err;
1139 		case READSTRTRUNC:
1140 			np_error(hdr->tag, "wname too long");
1141 			return;
1142 		}
1143 
1144 		if (*wnam == '\0' ||
1145 		    strchr(wnam, '/') != NULL ||
1146 		    !strcmp(wnam, ".")) {
1147 			errno = EINVAL;
1148 			goto cantopen;
1149 		}
1150 
1151 		if ((fd = openat(oldfd, wnam, O_RDONLY|O_DIRECTORY)) == -1 &&
1152 		    errno != ENOTDIR)
1153 			goto cantopen;
1154 
1155 		if ((fd == -1 && fstatat(oldfd, wnam, &sb, 0) == -1) ||
1156 		    (fd != -1 && fstat(fd, &sb) == -1))
1157 			goto cantopen;
1158 
1159 		qid_update_from_sb(&wqid[nwqid], &sb);
1160 
1161 		/* reached a file but we still have other components */
1162 		if (fd == -1 && nwqid+1 < nwname)
1163 			goto cantopen;
1164 
1165 		/* reached the end and found a file */
1166 		if (fd == -1 && nwqid+1 == nwname)
1167 			continue;
1168 
1169 		if (oldfd != f->dir->fd)
1170 			close(oldfd);
1171 		oldfd = fd;
1172 	}
1173 
1174 	if (len != 0)
1175 		goto err;
1176 
1177 	/*
1178 	 * If fd is -1 we've reached a file, otherwise we've just
1179 	 * reached another directory.  We must pay attention to what
1180 	 * file descriptor we use to create the dir, because if we've
1181 	 * reached a file and oldfd is f->dir->fd then we *must* share
1182 	 * the same dir (it was a walk of one path from a directory to a
1183 	 * file, otherwise fun is bound to happen as soon as the client
1184      	 * closes the fid for the directory but keeps the one for the
1185 	 * file.
1186 	 */
1187 	if (fd == -1 && oldfd == f->dir->fd)
1188 		dir = f->dir;
1189 	else if (fd == -1)
1190 		dir = new_dir(oldfd);
1191 	else
1192 		dir = new_dir(fd);
1193 
1194 	if (dir == NULL)
1195 		fatal("new_dir");
1196 
1197 	if (nf == NULL) {
1198 		if ((nf = new_fid(dir, newfid, wnam, &wqid[nwqid-1])) == NULL)
1199 			fatal("new fid");
1200 	} else {
1201 		/* update the dir */
1202 		dir_decref(nf->dir);
1203 		nf->dir = dir_incref(dir);
1204 	}
1205 
1206 	np_walk(hdr->tag, nwqid, wqid);
1207 	return;
1208 
1209 cantopen:
1210 	if (oldfd != f->dir->fd)
1211 		close(oldfd);
1212 	no = errno;
1213 	if (nwqid == 0)
1214 		np_error(hdr->tag, strerror(no));
1215 	else
1216 		np_walk(hdr->tag, nwqid, wqid);
1217 	return;
1218 
1219 err:
1220 	client_send_listener(IMSG_CLOSE, NULL, 0);
1221 	client_shutdown();
1222 }
1223 
1224 static inline int
1225 npmode_to_unix(uint8_t mode, int *flags)
1226 {
1227 	switch (mode & 0x0F) {
1228 	case KOREAD:
1229 		*flags = O_RDONLY;
1230 		break;
1231 	case KOWRITE:
1232 		*flags = O_WRONLY;
1233 		break;
1234 	case KORDWR:
1235 		*flags = O_RDWR;
1236 		break;
1237 	case KOEXEC:
1238 		log_warnx("tried to open something with KOEXEC");
1239 		/* fallthrough */
1240 	default:
1241 		return -1;
1242 	}
1243 
1244 	if (mode & KOTRUNC)
1245 		*flags |= O_TRUNC;
1246 	if (mode & KORCLOSE)
1247 		*flags |= O_CLOEXEC;
1248 
1249 	return 0;
1250 }
1251 
1252 static void
1253 topen(struct np_msg_header *hdr, const uint8_t *data, size_t len)
1254 {
1255 	struct stat	 sb;
1256 	struct qid	 qid;
1257 	struct fid	*f;
1258 	uint32_t	 fid;
1259 	uint8_t		 mode;
1260 	const char	*path;
1261 
1262 	/* fid[4] mode[1] */
1263 	if (!NPREAD32("fid", &fid, &data, &len) ||
1264 	    !NPREAD8("mode", &mode, &data, &len) ||
1265 	    len != 0) {
1266 		client_send_listener(IMSG_CLOSE, NULL, 0);
1267 		client_shutdown();
1268 		return;
1269 	}
1270 
1271 	if ((f = fid_by_id(fid)) == NULL || f->fd != -1) {
1272 		np_error(hdr->tag, "invalid fid");
1273 		return;
1274 	}
1275 
1276 	if (npmode_to_unix(mode, &f->iomode) == -1) {
1277 		np_error(hdr->tag, "invalid mode");
1278 		return;
1279 	}
1280 
1281 	path = f->fname;
1282 	if (f->qid.type & QTDIR)
1283 		path = ".";
1284 
1285 	if ((f->fd = openat(f->dir->fd, path, f->iomode)) == -1) {
1286 		np_error(hdr->tag, strerror(errno));
1287 		return;
1288 	}
1289 
1290 	if (fstat(f->fd, &sb) == -1)
1291 		fatal("fstat");
1292 
1293 	if (S_ISDIR(sb.st_mode)) {
1294 		if ((f->d = fdopendir(f->fd)) == NULL) {
1295 			np_errno(hdr->tag);
1296 			close(f->fd);
1297 			f->fd = -1;
1298 			return;
1299 		}
1300 
1301 		if ((f->evb = evbuffer_new()) == NULL) {
1302 			np_errno(hdr->tag);
1303 			closedir(f->d);
1304 			f->d = NULL;
1305 			f->fd = -1;
1306 		}
1307 	}
1308 
1309 	f->offset = 0;
1310 
1311 	qid_update_from_sb(&qid, &sb);
1312 	np_open(hdr->tag, &qid, sb.st_blksize);
1313 }
1314 
1315 static void
1316 tcreate(struct np_msg_header *hdr, const uint8_t *data, size_t len)
1317 {
1318 	struct stat	 sb;
1319 	struct qid	 qid;
1320 	struct fid	*f;
1321 	uint32_t	 fid, perm;
1322 	uint8_t		 mode;
1323 	char		 name[PATH_MAX];
1324 
1325 	/* fid[4] name[s] perm[4] mode[1] */
1326 	if (!NPREAD32("fid", &fid, &data, &len))
1327 		goto err;
1328 	switch (NPREADSTR("name", name, sizeof(name), &data, &len)) {
1329 	case READSTRERR:
1330 		goto err;
1331 	case READSTRTRUNC:
1332 		np_error(hdr->tag, "name too long");
1333 		return;
1334 	}
1335 	if (!NPREAD32("perm", &perm, &data, &len) ||
1336 	    !NPREAD8("mode", &mode, &data, &len) ||
1337 	    len != 0)
1338 		goto err;
1339 
1340 	if (!strcmp(name, ".") || !strcmp(name, "..") ||
1341 	    strchr(name, '/') != NULL) {
1342 		np_error(hdr->tag, "invalid name");
1343 		return;
1344 	}
1345 
1346 	if ((f = fid_by_id(fid)) == NULL || f->fd != -1) {
1347 		np_error(hdr->tag, "invalid fid");
1348 		return;
1349 	}
1350 
1351 	if (!(f->qid.type & QTDIR)) {
1352 		np_error(hdr->tag, "fid doesn't identify a directory");
1353 		return;
1354 	}
1355 
1356 	if (npmode_to_unix(mode, &f->iomode) == -1) {
1357 		np_error(hdr->tag, "invalid mode");
1358 		return;
1359 	}
1360 
1361 	if (f->iomode & O_RDONLY) {
1362 		np_error(hdr->tag, "can't create a read-only file");
1363 		return;
1364 	}
1365 
1366 	/* TODO: parse the mode */
1367 
1368 	if (perm & 0x80000000) {
1369 		/* create a directory */
1370 		f->fd = mkdirat(f->dir->fd, name, 0755);
1371 	} else {
1372 		/* create a file */
1373 		f->fd = openat(f->dir->fd, name, f->iomode | O_CREAT | O_TRUNC,
1374 		    0644);
1375 	}
1376 
1377 	if (f->fd == -1) {
1378 		np_errno(hdr->tag);
1379 		return;
1380 	}
1381 
1382 	if (fstat(f->fd, &sb) == -1)
1383 		fatal("fstat");
1384 
1385 	if (S_ISDIR(sb.st_mode)) {
1386 		if ((f->d = fdopendir(f->fd)) == NULL) {
1387 			np_errno(hdr->tag);
1388 			close(f->fd);
1389 			f->fd = -1;
1390 			return;
1391 		}
1392 
1393 		if ((f->evb = evbuffer_new()) == NULL) {
1394 			np_errno(hdr->tag);
1395 			closedir(f->d);
1396 			f->d = NULL;
1397 			f->fd = -1;
1398 		}
1399 	}
1400 
1401 	f->offset = 0;
1402 
1403 	qid_update_from_sb(&qid, &sb);
1404 	np_create(hdr->tag, &qid, sb.st_blksize);
1405 
1406 	return;
1407 
1408 err:
1409 	client_send_listener(IMSG_CLOSE, NULL, 0);
1410 	client_shutdown();
1411 }
1412 
1413 static inline void
1414 serialize_stat(const char *fname, struct stat *sb, struct evbuffer *evb)
1415 {
1416 	struct qid	 qid;
1417 	const char	*uid, *gid, *muid;
1418 	size_t		 tot;
1419 	uint16_t	 namlen, uidlen, gidlen, ulen;
1420 
1421 	qid_update_from_sb(&qid, sb);
1422 
1423 	/* TODO: fill these fields */
1424 	uid = "";
1425 	gid = "";
1426 	muid = "";
1427 
1428 	namlen = strlen(fname);
1429 	uidlen = strlen(uid);
1430 	gidlen = strlen(gid);
1431 	ulen = strlen(muid);
1432 
1433 	tot = NPSTATSIZ(namlen, uidlen, gidlen, ulen);
1434 	if (tot > UINT32_MAX) {
1435 		log_warnx("stat info for dir entry %s would overflow",
1436 		    fname);
1437 		return;
1438 	}
1439 
1440 	np_write16(evb, tot);			/*	size[2]		*/
1441 	np_write16(evb, sb->st_rdev);		/*	type[2]		*/
1442 	np_write32(evb, sb->st_dev);		/*	dev[4]		*/
1443 	np_qid(evb, &qid);			/*	qid[13]		*/
1444 
1445 	/* XXX: translate? */
1446 	np_write32(evb, sb->st_mode);		/*	mode[4]		*/
1447 
1448 	np_write32(evb, sb->st_atim.tv_sec);	/*	atime[4]	*/
1449 	np_write32(evb, sb->st_mtim.tv_sec);	/*	mtime[4]	*/
1450 
1451 	/* special case: directories have size 0 */
1452 	if (qid.type & QTDIR)
1453 		np_write64(evb, 0);
1454 	else
1455 		np_write64(evb, sb->st_size);	/*	length[8]	*/
1456 
1457 	np_string(evb, namlen, fname);		/*	name[s]		*/
1458 	np_string(evb, uidlen, uid);		/*	uid[s]		*/
1459 	np_string(evb, gidlen, gid);		/*	gid[s]		*/
1460 	np_string(evb, ulen, muid);		/*	muid[s]		*/
1461 }
1462 
1463 static void
1464 tread(struct np_msg_header *hdr, const uint8_t *data, size_t len)
1465 {
1466 	struct fid	*f;
1467 	ssize_t		 r;
1468 	size_t		 howmuch;
1469 	uint64_t	 off;
1470 	uint32_t	 fid, count;
1471 	char		 buf[2048];
1472 
1473 	/* fid[4] offset[8] count[4] */
1474 	if (!NPREAD32("fid", &fid, &data, &len) ||
1475 	    !NPREAD64("offset", &off, &data, &len) ||
1476 	    !NPREAD32("count", &count, &data, &len) ||
1477 	    len != 0) {
1478 		client_send_listener(IMSG_CLOSE, NULL, 0);
1479 		client_shutdown();
1480 		return;
1481 	}
1482 
1483 	if ((f = fid_by_id(fid)) == NULL || f->fd == -1) {
1484 		np_error(hdr->tag, "invalid fid");
1485 		return;
1486 	}
1487 
1488 	if (TYPE_OVERFLOW(off_t, off)) {
1489 		log_warnx("unexpected off_t size");
1490 		np_error(hdr->tag, "invalid offset");
1491 		return;
1492 	}
1493 
1494 	if (f->d == NULL) {
1495 		/* read a file */
1496 		howmuch = MIN(sizeof(buf), count);
1497 		r = pread(f->fd, buf, howmuch, (off_t)off);
1498 		if (r == -1)
1499 			np_errno(hdr->tag);
1500 		else
1501 			np_read(hdr->tag, r, buf);
1502 	} else {
1503 		if (off == 0 && f->offset != 0) {
1504 			rewinddir(f->d);
1505 			f->offset = 0;
1506 			evbuffer_drain(f->evb, EVBUFFER_LENGTH(f->evb));
1507 		}
1508 
1509 		if (off != f->offset) {
1510 			np_error(hdr->tag, "can't seek in directories");
1511 			return;
1512 		}
1513 
1514 		while (EVBUFFER_LENGTH(f->evb) < count) {
1515 			struct dirent *d;
1516 			struct stat sb;
1517 
1518 			if ((d = readdir(f->d)) == NULL)
1519 				break;
1520 			if (fstatat(f->fd, d->d_name, &sb, 0) == -1) {
1521 				warn("fstatat");
1522 				continue;
1523 			}
1524 			serialize_stat(d->d_name, &sb, f->evb);
1525 		}
1526 
1527 		count = MIN(count, EVBUFFER_LENGTH(f->evb));
1528 		np_read(hdr->tag, count, EVBUFFER_DATA(f->evb));
1529 		evbuffer_drain(f->evb, count);
1530 
1531 		f->offset += count;
1532 	}
1533 }
1534 
1535 static void
1536 twrite(struct np_msg_header *hdr, const uint8_t *data, size_t len)
1537 {
1538 	struct fid	*f;
1539 	ssize_t		 r;
1540 	uint64_t	 off;
1541 	uint32_t	 fid, count;
1542 
1543 	/* fid[4] offset[8] count[4] data[count] */
1544 	if (!NPREAD32("fid", &fid, &data, &len) ||
1545 	    !NPREAD64("off", &off, &data, &len) ||
1546 	    !NPREAD32("count", &count, &data, &len) ||
1547 	    len != count) {
1548 		client_send_listener(IMSG_CLOSE, NULL, 0);
1549 		client_shutdown();
1550 		return;
1551 	}
1552 
1553 	if ((f = fid_by_id(fid)) == NULL || f->fd == -1) {
1554 		np_error(hdr->tag, "invalid fid");
1555 		return;
1556 	}
1557 
1558 	if (!(f->iomode & O_WRONLY) &&
1559 	    !(f->iomode & O_RDWR)) {
1560 		np_error(hdr->tag, "fid not opened for writing");
1561 		return;
1562 	}
1563 
1564 	if (TYPE_OVERFLOW(off_t, off)) {
1565 		log_warnx("unexpected off_t size");
1566 		np_error(hdr->tag, "invalid offset");
1567 		return;
1568 	}
1569 
1570 	if ((r = pwrite(f->fd, data, len, off)) == -1)
1571 		np_errno(hdr->tag);
1572 	else
1573 		np_write(hdr->tag, r);
1574 }
1575 
1576 static void
1577 tstat(struct np_msg_header *hdr, const uint8_t *data, size_t len)
1578 {
1579 	struct evbuffer	*evb;
1580 	struct stat	 sb;
1581 	struct fid	*f;
1582 	int		 r;
1583 	uint32_t	 fid;
1584 
1585 	/* fid[4] */
1586 	if (!NPREAD32("fid", &fid, &data, &len) ||
1587 	    len != 0) {
1588 		client_send_listener(IMSG_CLOSE, NULL, 0);
1589 		client_shutdown();
1590 		return;
1591 	}
1592 
1593 	/*
1594 	 * plan9' stat(9P) is not clear on whether the stat is allowed
1595 	 * on opened fids or not.  We're allowing stat regardless of the
1596 	 * status of the fid.
1597 	 */
1598 
1599 	if ((f = fid_by_id(fid)) == NULL) {
1600 		np_error(hdr->tag, "invalid fid");
1601 		return;
1602 	}
1603 
1604 	if ((evb = evbuffer_new()) == NULL)
1605 		fatal("evbuffer_new");
1606 
1607 	if (f->fd != -1)
1608 		r = fstat(f->fd, &sb);
1609 	else if (f->qid.type & QTDIR)
1610 		r = fstat(f->dir->fd, &sb);
1611 	else
1612 		r = fstatat(f->dir->fd, f->fname, &sb, 0);
1613 
1614 	if (r == -1) {
1615 		np_errno(hdr->tag);
1616 		evbuffer_free(evb);
1617 		return;
1618 	}
1619 
1620 	serialize_stat(f->fname, &sb, evb);
1621 	np_stat(hdr->tag, EVBUFFER_LENGTH(evb), EVBUFFER_DATA(evb));
1622 	evbuffer_free(evb);
1623 }
1624 
1625 static void
1626 twstat(struct np_msg_header *hdr, const uint8_t *data, size_t len)
1627 {
1628 	struct timespec	 times[2];
1629 	struct np_stat	 st;
1630 	struct fid	*f;
1631 	int		 r;
1632 	uint32_t	 fid;
1633 	char		 name[PATH_MAX];
1634 
1635 	/* fid[4] stat[n] */
1636 	if (!NPREAD32("fid", &fid, &data, &len))
1637 		goto err;
1638 
1639 	switch (NPREADST("stat", &st, name, sizeof(name), &data, &len)) {
1640 	case READSTRERR:
1641 		goto err;
1642 	case READSTRTRUNC:
1643 		log_warnx("wstat new name would overflow");
1644 		np_error(hdr->tag, "new name too long");
1645 		return;
1646 	}
1647 
1648 	/*
1649 	 * We skip the reading of some fields voluntarily because we
1650 	 * don't support chown, so len will always be > 0!
1651 	 */
1652 #ifdef notyet
1653 	if (len != 0)
1654 		goto err;
1655 #endif
1656 
1657 	if ((f = fid_by_id(fid)) == NULL) {
1658 		np_error(hdr->tag, "invalid fid");
1659 		return;
1660 	}
1661 
1662 	/*
1663 	 * 9P wants these edits to be done in an atomic fashion,
1664 	 * something that I don't think it's possible on UNIX without
1665 	 * some special kernel help.  Changing atime or mtime,
1666 	 * permissions, or rename the file are different syscalls.
1667 	 *
1668 	 * Also, silently ignore stuff we can't/don't want to modify.
1669 	 */
1670 
1671 	/* change the permissions */
1672 	if (st.mode != (uint32_t)-1) {
1673 		mode_t m = st.mode & 0x7F; /* silently truncate higer bits */
1674 		if (f->fd != -1)
1675 			r = fchmod(f->fd, m);
1676 		else
1677 			r = fchmodat(f->dir->fd, f->fname, m, 0);
1678 
1679 		if (r == -1) {
1680 			np_errno(hdr->tag);
1681 			return;
1682 		}
1683 	}
1684 
1685 	/* change the atime/mtime of the fid, opened or not */
1686 	if (st.atime != (uint32_t)-1 || st.mtime != (uint32_t)-1) {
1687 		times[0].tv_nsec = UTIME_OMIT;
1688 		times[1].tv_nsec = UTIME_OMIT;
1689 
1690 		if (st.atime != (uint32_t)-1) {
1691 			times[0].tv_sec = st.atime;
1692 			times[0].tv_nsec = 0;
1693 		}
1694 		if (st.mtime != (uint32_t)-1) {
1695 			times[1].tv_sec = st.mtime;
1696 			times[1].tv_nsec = 0;
1697 		}
1698 
1699 		if (f->fd != -1)
1700 			r = futimens(f->fd, times);
1701 		else
1702 			r = utimensat(f->dir->fd, f->fname, times, 0);
1703 
1704 		if (r == -1) {
1705 			np_errno(hdr->tag);
1706 			return;
1707 		}
1708 	}
1709 
1710 	/* truncate */
1711 	if (st.length != (uint64_t)-1) {
1712 		if (f->fd == -1) {
1713 			np_error(hdr->tag, "can't truncate a non-opened fid");
1714 			return;
1715 		}
1716 
1717 		if (f->qid.type & QTDIR && st.length != 0) {
1718 			np_error(hdr->tag, "can't truncate directories");
1719 			return;
1720 		}
1721 
1722 		if (TYPE_OVERFLOW(off_t, st.length)) {
1723 			log_warnx("truncate request overflows off_t: %"PRIu64,
1724 			    st.length);
1725 			np_error(hdr->tag, "length overflows");
1726 			return;
1727 		}
1728 
1729 		if (f->qid.type == 0 &&
1730 		    ftruncate(f->fd, st.length) == -1) {
1731 			np_errno(hdr->tag);
1732 			return;
1733 		}
1734 	}
1735 
1736 	/* rename (change the name entry) */
1737 	if (*st.name != '\0') {
1738 		struct stat sb;
1739 		const char *newname;
1740 
1741 		/*
1742 		 * XXX: 9P requires that we disallow changing the name
1743 		 * to that of an existing file.  We can't do that
1744 		 * atomically (rename is happy about stealing names)
1745 		 * so this is just a best effort.
1746 		 */
1747 		if (fstatat(f->dir->fd, st.name, &sb, 0) == -1 &&
1748 		    errno != ENOENT) {
1749 			np_error(hdr->tag, "target file exists");
1750 			return;
1751 		}
1752 
1753 		r = renameat(f->dir->fd, f->fname, f->dir->fd, st.name);
1754 		if (r == -1) {
1755 			np_errno(hdr->tag);
1756 			return;
1757 		}
1758 
1759 		/* fix the fid so it points to the new file */
1760 
1761 		if ((newname = strchr(st.name, '/')) != NULL)
1762 			newname++; /* skip / */
1763 		else
1764 			newname = st.name;
1765 		strlcpy(f->fname, newname, sizeof(f->fname));
1766 
1767 		if (strchr(st.name, '/') != NULL) {
1768 			struct dir *dir;
1769 			char *dname;
1770 			int fd;
1771 
1772 			dname = dirname(st.name);
1773 			fd = openat(f->dir->fd, dname, O_RDONLY|O_DIRECTORY);
1774 			if (fd == -1) {
1775 				np_errno(hdr->tag);
1776 				free_fid(f);
1777 				return;
1778 			}
1779 
1780 			if ((dir = new_dir(fd)) == NULL) {
1781 				np_errno(hdr->tag);
1782 				free_fid(f);
1783 				return;
1784 			}
1785 
1786 			dir_decref(f->dir);
1787 			f->dir = dir_incref(dir);
1788 		}
1789 	}
1790 
1791 	np_wstat(hdr->tag);
1792 	return;
1793 
1794 err:
1795 	client_send_listener(IMSG_CLOSE, NULL, 0);
1796 	client_shutdown();
1797 }
1798 
1799 static void
1800 tremove(struct np_msg_header *hdr, const uint8_t *data, size_t len)
1801 {
1802 	struct fid	*f;
1803 	uint32_t	 fid;
1804 	int		 r;
1805 	char		 dirpath[PATH_MAX + 3];
1806 
1807 	/* fid[4] */
1808 	if (!NPREAD32("fid", &fid, &data, &len) ||
1809 	    len != 0) {
1810 		client_send_listener(IMSG_CLOSE, NULL, 0);
1811 		client_shutdown();
1812 		return;
1813 	}
1814 
1815 	if ((f = fid_by_id(fid)) == NULL) {
1816 		np_error(hdr->tag, "invalid fid");
1817 		return;
1818 	}
1819 
1820 	if (f->qid.type & QTDIR) { /* directory */
1821 		strlcpy(dirpath, "../", sizeof(dirpath));
1822 		strlcat(dirpath, f->fname, sizeof(dirpath));
1823 		r = unlinkat(f->dir->fd, dirpath, AT_REMOVEDIR);
1824 	} else /* file */
1825 		r = unlinkat(f->dir->fd, f->fname, 0);
1826 
1827 	if (r == -1)
1828 		np_errno(hdr->tag);
1829 	else
1830 		np_remove(hdr->tag);
1831 
1832 	free_fid(f);
1833 }
1834 
1835 static void
1836 handle_message(struct imsg *imsg, size_t len)
1837 {
1838 	struct msg {
1839 		uint8_t	 type;
1840 		void	(*fn)(struct np_msg_header *, const uint8_t *, size_t);
1841 	} msgs[] = {
1842 		{Tversion,	tversion},
1843 		{Tattach,	tattach},
1844 		{Tclunk,	tclunk},
1845 		{Tflush,	tflush},
1846 		{Twalk,		twalk},
1847 		{Topen,		topen},
1848 		{Tcreate,	tcreate},
1849 		{Tread,		tread},
1850 		{Twrite,	twrite},
1851 		{Tstat,		tstat},
1852 		{Twstat,	twstat},
1853 		{Tremove,	tremove},
1854 	};
1855 	struct np_msg_header	 hdr;
1856 	size_t			 i;
1857 	uint8_t			*data;
1858 
1859 #if DEBUG_PACKETS
1860 	hexdump("incoming packet", imsg->data, len);
1861 #endif
1862 
1863 	parse_message(imsg->data, len, &hdr, &data);
1864 	len -= HEADERSIZE;
1865 
1866 	log_debug("got request: len=%d type=%d[%s] tag=%d",
1867 	    hdr.len, hdr.type, pp_msg_type(hdr.type), hdr.tag);
1868 
1869 	if (!handshaked && hdr.type != Tversion) {
1870 		client_send_listener(IMSG_CLOSE, NULL, 0);
1871 		client_shutdown();
1872 		return;
1873 	}
1874 
1875 	for (i = 0; i < sizeof(msgs)/sizeof(msgs[0]); ++i) {
1876 		if (msgs[i].type != hdr.type)
1877 			continue;
1878 
1879 		msgs[i].fn(&hdr, data, len);
1880 		return;
1881 	}
1882 
1883 	np_error(hdr.tag, "Not supported.");
1884 }