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Date:: Fri Jan 28 21:49:15 2022 UTC
Message:: cache listener flags in struct client this saves us from the small chance that a client accepted before reconf uses the flags from a listener post reconf.
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1 /*
2  * Copyright (c) 2021, 2022 Omar Polo <op@omarpolo.com>
3  * Copyright (c) 2018 Florian Obser <florian@openbsd.org>
4  * Copyright (c) 2004, 2005 Claudio Jeker <claudio@openbsd.org>
5  * Copyright (c) 2004 Esben Norby <norby@openbsd.org>
6  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
7  *
8  * Permission to use, copy, modify, and distribute this software for any
9  * purpose with or without fee is hereby granted, provided that the above
10  * copyright notice and this permission notice appear in all copies.
11  *
12  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
13  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
14  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
15  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
16  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
17  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
18  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
19  */
20 
21 #include "compat.h"
22 
23 #include <sys/socket.h>
24 #include <sys/types.h>
25 #include <sys/uio.h>
26 
27 #include <endian.h>
28 #include <errno.h>
29 #include <inttypes.h>
30 #include <pwd.h>
31 #include <signal.h>
32 #include <stdint.h>
33 #include <stdio.h>
34 #include <stdlib.h>
35 #include <string.h>
36 #include <syslog.h>
37 #include <unistd.h>
38 
39 #include "control.h"
40 #include "kami.h"
41 #include "kamid.h"
42 #include "listener.h"
43 #include "log.h"
44 #include "sandbox.h"
45 #include "utils.h"
46 
47 static struct kd_conf	*listener_conf;
48 static struct imsgev	*iev_main;
49 
50 static void	listener_sig_handler(int, short, void *);
51 __dead void	listener_shutdown(void);
52 
53 SPLAY_HEAD(clients_tree_id, client) clients;
54 
55 struct client {
56 	uint32_t		 id;
57 	uint32_t		 lid;
58 	uint32_t		 lflags;
59 	uint32_t		 msize;
60 	int			 fd;
61 	struct tls		*ctx;
62 	struct event		 event;
63 	struct imsgev		 iev;
64 	struct bufferevent	*bev;
65 	SPLAY_ENTRY(client)	 sp_entry;
66 };
67 
68 static void	listener_imsg_event_add(struct imsgev *, void *);
69 static void	listener_dispatch_client(int, short, void *);
70 static int	listener_imsg_compose_client(struct client *, int,
71     uint32_t, const void *, uint16_t);
72 
73 static void	apply_config(struct kd_conf *);
74 static void	handle_accept(int, short, void *);
75 
76 static void	handle_handshake(int, short, void *);
77 static void	client_read(struct bufferevent *, void *);
78 static void	client_write(struct bufferevent *, void *);
79 static void	client_error(struct bufferevent *, short, void *);
80 static void	client_tls_readcb(int, short, void *);
81 static void	client_tls_writecb(int, short, void *);
82 static void	close_conn(struct client *);
83 static void	handle_close(int, short, void *);
84 
85 static inline int
86 clients_tree_cmp(struct client *a, struct client *b)
87 {
88 	if (a->id == b->id)
89 		return 0;
90 	else if (a->id < b->id)
91 		return -1;
92 	else
93 		return +1;
94 }
95 
96 SPLAY_PROTOTYPE(clients_tree_id, client, sp_entry, clients_tree_cmp);
97 SPLAY_GENERATE(clients_tree_id, client, sp_entry, clients_tree_cmp)
98 
99 static void
100 listener_sig_handler(int sig, short event, void *d)
101 {
102 	/*
103 	 * Normal signal handler rules don't apply because libevent
104 	 * decouples for us.
105 	 */
106 
107 	switch (sig) {
108 	case SIGINT:
109 	case SIGTERM:
110 		listener_shutdown();
111 	default:
112 		fatalx("unexpected signal %d", sig);
113 	}
114 }
115 
116 void
117 listener(int debug, int verbose)
118 {
119 	struct event		 ev_sigint, ev_sigterm;
120 	struct passwd		*pw;
121 
122 	/* listener_conf = config_new_empty(); */
123 
124 	log_init(debug, LOG_DAEMON);
125 	log_setverbose(verbose);
126 
127 	if ((pw = getpwnam(KD_USER)) == NULL)
128 		fatal("getpwnam");
129 
130 	if (chroot(pw->pw_dir) == -1)
131 		fatal("chroot");
132 	if (chdir("/") == -1)
133 		fatal("chdir(\"/\")");
134 
135 	setproctitle("listener");
136 	log_procinit("listener");
137 
138 	if (setgroups(1, &pw->pw_gid) ||
139 	    setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) ||
140 	    setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid))
141 		fatal("can't drop privileges");
142 
143 	event_init();
144 
145 	/* Setup signal handlers(s). */
146 	signal_set(&ev_sigint, SIGINT, listener_sig_handler, NULL);
147 	signal_set(&ev_sigterm, SIGTERM, listener_sig_handler, NULL);
148 
149 	signal_add(&ev_sigint, NULL);
150 	signal_add(&ev_sigterm, NULL);
151 
152 	signal(SIGPIPE, SIG_IGN);
153 	signal(SIGHUP, SIG_IGN);
154 
155 	/* Setup pipe and event handler to the main process. */
156 	if ((iev_main = malloc(sizeof(*iev_main))) == NULL)
157 		fatal(NULL);
158 
159 	imsg_init(&iev_main->ibuf, 3);
160 	iev_main->handler = listener_dispatch_main;
161 
162 	/* Setup event handlers. */
163 	iev_main->events = EV_READ;
164 	event_set(&iev_main->ev, iev_main->ibuf.fd, iev_main->events,
165 	    iev_main->handler, iev_main);
166 	event_add(&iev_main->ev, NULL);
167 
168 	sandbox_listener();
169 	event_dispatch();
170 	listener_shutdown();
171 }
172 
173 __dead void
174 listener_shutdown(void)
175 {
176 	msgbuf_clear(&iev_main->ibuf.w);
177 	close(iev_main->ibuf.fd);
178 
179 	clear_config(listener_conf);
180 
181 	free(iev_main);
182 
183 	log_info("listener exiting");
184 	exit(0);
185 }
186 
187 static void
188 listener_receive_config(struct imsg *imsg, struct kd_conf **nconf,
189     struct kd_pki_conf **pki)
190 {
191 	struct kd_listen_conf *listen;
192 	char *t;
193 
194 	switch (imsg->hdr.type) {
195 	case IMSG_RECONF_CONF:
196 		if (*nconf != NULL)
197 			fatalx("%s: IMSG_RECONF_CONF already in "
198 			    "progress", __func__);
199 
200 		if (listener_conf != NULL)
201 			fatalx("%s: don't know how reload the "
202 			    "configuration yet", __func__);
203 
204 		if (IMSG_DATA_SIZE(*imsg) != sizeof(struct kd_conf))
205 			fatalx("%s: IMSG_RECONF_CONF wrong length: %lu",
206 			    __func__, IMSG_DATA_SIZE(*imsg));
207 		if ((*nconf = malloc(sizeof(**nconf))) == NULL)
208 			fatal(NULL);
209 		memcpy(*nconf, imsg->data, sizeof(**nconf));
210 		STAILQ_INIT(&(*nconf)->pki_head);
211 		STAILQ_INIT(&(*nconf)->table_head);
212 		STAILQ_INIT(&(*nconf)->listen_head);
213 		break;
214 	case IMSG_RECONF_PKI:
215 		if (*nconf == NULL)
216 			fatalx("%s: IMSG_RECONF_PKI without "
217 			    "IMSG_RECONF_CONF", __func__);
218 		*pki = xcalloc(1, sizeof(**pki));
219 		t = imsg->data;
220 		t[IMSG_DATA_SIZE(*imsg)-1] = '\0';
221 		strlcpy((*pki)->name, t, sizeof((*pki)->name));
222 		break;
223 	case IMSG_RECONF_PKI_CERT:
224 		if (*pki == NULL)
225 			fatalx("%s: IMSG_RECONF_PKI_CERT without "
226 			    "IMSG_RECONF_PKI", __func__);
227 		(*pki)->certlen = IMSG_DATA_SIZE(*imsg);
228 		(*pki)->cert = xmemdup(imsg->data, (*pki)->certlen);
229 		break;
230 	case IMSG_RECONF_PKI_KEY:
231 		if (*pki == NULL)
232 			fatalx("%s: IMSG_RECONF_PKI_KEY without "
233 			    "IMSG_RECONF_PKI", __func__);
234 		(*pki)->keylen = IMSG_DATA_SIZE(*imsg);
235 		(*pki)->key = xmemdup(imsg->data, (*pki)->keylen);
236 		STAILQ_INSERT_HEAD(&(*nconf)->pki_head, *pki, entry);
237 		pki = NULL;
238 		break;
239 	case IMSG_RECONF_LISTEN:
240 		if (*nconf == NULL)
241 			fatalx("%s: IMSG_RECONF_LISTEN without "
242 			    "IMSG_RECONF_CONF", __func__);
243 		if (IMSG_DATA_SIZE(*imsg) != sizeof(*listen))
244 			fatalx("%s: IMSG_RECONF_LISTEN wrong length: %lu",
245 			    __func__, IMSG_DATA_SIZE(*imsg));
246 		listen = xcalloc(1, sizeof(*listen));
247 		memcpy(listen, imsg->data, sizeof(*listen));
248 		memset(&listen->entry, 0, sizeof(listen->entry));
249 		if ((listen->fd = imsg->fd) == -1)
250 			fatalx("%s: IMSG_RECONF_LISTEN no fd",
251 			    __func__);
252 		listen->auth_table = NULL;
253 		memset(&listen->ev, 0, sizeof(listen->ev));
254 		STAILQ_INSERT_HEAD(&(*nconf)->listen_head, listen, entry);
255 		break;
256 	case IMSG_RECONF_END:
257 		if (*nconf == NULL)
258 			fatalx("%s: IMSG_RECONF_END without "
259 			    "IMSG_RECONF_CONF", __func__);
260 		apply_config(*nconf);
261 		*nconf = NULL;
262 		break;
263 	}
264 }
265 
266 static inline struct kd_listen_conf *
267 listen_by_id(uint32_t id)
268 {
269 	struct kd_listen_conf *l;
270 
271 	STAILQ_FOREACH(l, &listener_conf->listen_head, entry) {
272 		if (l->id == id)
273 			return l;
274 	}
275 	return NULL;
276 }
277 
278 void
279 listener_dispatch_main(int fd, short event, void *d)
280 {
281 	static struct kd_conf		*nconf;
282 	static struct kd_pki_conf	*pki;
283 	struct kd_listen_conf		*listen;
284 	struct client			*client, find;
285 	struct imsg			 imsg;
286 	struct imsgev			*iev = d;
287 	struct imsgbuf			*ibuf;
288 	ssize_t				 n;
289 	int				 shut = 0;
290 
291 	ibuf = &iev->ibuf;
292 
293 	if (event & EV_READ) {
294 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
295 			fatal("imsg_read error");
296 		if (n == 0)	/* Connection closed. */
297 			shut = 1;
298 	}
299 	if (event & EV_WRITE) {
300 		if ((n = msgbuf_write(&ibuf->w)) == -1 && errno != EAGAIN)
301 			fatal("msgbuf_write");
302 		if (n == 0)	/* Connection closed. */
303 			shut = 1;
304 	}
305 
306 	for (;;) {
307 		if ((n = imsg_get(ibuf, &imsg)) == -1)
308 			fatal("%s: imsg_get error", __func__);
309 		if (n == 0)	/* No more messages. */
310 			break;
311 
312 		switch (imsg.hdr.type) {
313 		case IMSG_CTL_LOG_VERBOSE:
314 			if (IMSG_DATA_SIZE(imsg) != sizeof(verbose))
315 				fatalx("wrong size for IMSG_CTL_LOG_VERBOSE");
316 			memcpy(&verbose, imsg.data, sizeof(verbose));
317 			log_setverbose(verbose);
318 			SPLAY_FOREACH(client, clients_tree_id, &clients)
319 				listener_imsg_compose_client(client,
320 				    imsg.hdr.type, 0,
321 				    &verbose, sizeof(verbose));
322 			break;
323 		case IMSG_RECONF_CONF:
324 		case IMSG_RECONF_PKI:
325 		case IMSG_RECONF_PKI_CERT:
326 		case IMSG_RECONF_PKI_KEY:
327 		case IMSG_RECONF_LISTEN:
328 		case IMSG_RECONF_END:
329 			listener_receive_config(&imsg, &nconf, &pki);
330 			break;
331 		case IMSG_AUTH:
332 			if (IMSG_DATA_SIZE(imsg) != sizeof(struct kd_auth_proc))
333 				fatalx("mismatching size for IMSG_AUTH");
334 
335 			find.id = imsg.hdr.peerid;
336 			client = SPLAY_FIND(clients_tree_id, &clients, &find);
337 			if (client == NULL) {
338 				if (imsg.fd != -1)
339 					close(imsg.fd);
340 				break;
341 			}
342 			if (imsg.fd == -1) {
343 				log_info("got fd = -1, auth failed?");
344 				close_conn(client);
345 				break;
346 			}
347 			imsg_init(&client->iev.ibuf, imsg.fd);
348 			client->iev.events = EV_READ;
349 			client->iev.handler = listener_dispatch_client;
350 			event_set(&client->iev.ev, client->iev.ibuf.fd,
351 			    client->iev.events, client->iev.handler, client);
352 			listener_imsg_compose_client(client, IMSG_AUTH,
353 			    client->id, imsg.data, IMSG_DATA_SIZE(imsg));
354 
355 			client->bev = bufferevent_new(client->fd,
356 			    client_read, client_write, client_error,
357 			    client);
358 			if (client->bev == NULL) {
359 				log_info("failed to allocate client buffer");
360 				close_conn(client);
361 				return;
362 			}
363 
364 #if HAVE_EVENT2
365 			evbuffer_unfreeze(client->bev->input, 0);
366 			evbuffer_unfreeze(client->bev->output, 1);
367 #endif
368 
369 			if (client->lflags & L_TLS) {
370 				event_set(&client->bev->ev_read, client->fd,
371 				    EV_READ, client_tls_readcb, client->bev);
372 				event_set(&client->bev->ev_write, client->fd,
373 				    EV_WRITE, client_tls_writecb, client->bev);
374 			}
375 
376 			/*
377 			 * Read or write at least a header before
378 			 * firing the callbacks.  High watermark of 0
379 			 * to never stop reading/writing; probably to
380 			 * be revisited.
381 			 */
382 			/* bufferevent_setwatermark(client->bev, EV_READ|EV_WRITE, */
383 			    /* sizeof(struct np_msg_header), 0); */
384 			bufferevent_enable(client->bev, EV_READ|EV_WRITE);
385 			break;
386 
387 		default:
388 			log_debug("%s: unexpected imsg %d", __func__,
389 			    imsg.hdr.type);
390 			break;
391 		}
392 		imsg_free(&imsg);
393 	}
394 
395 	if (!shut)
396 		listener_imsg_event_add(iev, d);
397 	else {
398 		/* This pipe is dead.  Remove its event handler. */
399 		event_del(&iev->ev);
400 		log_warnx("pipe closed, shutting down...");
401 		event_loopexit(NULL);
402 	}
403 }
404 
405 int
406 listener_imsg_compose_main(int type, uint32_t peerid, const void *data,
407     uint16_t datalen)
408 {
409 	return imsg_compose_event(iev_main, type, peerid, 0, -1, data,
410 	    datalen);
411 }
412 
413 static void
414 listener_imsg_event_add(struct imsgev *iev, void *d)
415 {
416 	iev->events = EV_READ;
417 	if (iev->ibuf.w.queued)
418 		iev->events |= EV_WRITE;
419 
420 	event_del(&iev->ev);
421 	event_set(&iev->ev, iev->ibuf.fd, iev->events, iev->handler, d);
422 	event_add(&iev->ev, NULL);
423 }
424 
425 static void
426 listener_dispatch_client(int fd, short event, void *d)
427 {
428         struct client	 find, *client = d;
429 	struct imsg	 imsg;
430 	struct imsgev	*iev;
431 	struct imsgbuf	*ibuf;
432 	ssize_t		 n;
433 	int		 r, shut = 0;
434 
435 	iev = &client->iev;
436 	ibuf = &iev->ibuf;
437 
438 	if (event & EV_READ) {
439 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
440 			fatal("imsg_read error");
441 		if (n == 0)	/* Connection closed */
442 			shut = 1;
443 	}
444 
445 	if (event & EV_WRITE) {
446 		if ((n = msgbuf_write(&ibuf->w)) == -1 && errno != EAGAIN)
447 			fatal("msgbuf_write");
448 		if (n == 0)	/* Connection closed. */
449 			shut = 1;
450 	}
451 
452 	for (;;) {
453 		if ((n = imsg_get(ibuf, &imsg)) == -1)
454 			fatal("%s: imsg_get error", __func__);
455 		if (n == 0)	/* No more messages. */
456 			break;
457 
458 		switch (imsg.hdr.type) {
459 		case IMSG_BUF:
460 			find.id = imsg.hdr.peerid;
461 			client = SPLAY_FIND(clients_tree_id, &clients, &find);
462 			if (client == NULL) {
463 				log_info("got IMSG_BUF but client (%d) gone",
464 				    imsg.hdr.peerid);
465 				break;
466 			}
467 			r = bufferevent_write(client->bev, imsg.data,
468 			    IMSG_DATA_SIZE(imsg));
469 			if (r == -1) {
470 				log_warn("%s: bufferevent_write failed",
471 				    __func__);
472 				close_conn(client);
473 				break;
474 			}
475 			break;
476 
477 		case IMSG_MSIZE:
478 			if (IMSG_DATA_SIZE(imsg) != sizeof(client->msize))
479 				fatal("IMSG_MSIZE size mismatch: "
480 				    "got %zu want %zu", IMSG_DATA_SIZE(imsg),
481 				    sizeof(client->msize));
482 
483 			memcpy(&client->msize, imsg.data,
484 			    sizeof(client->msize));
485 
486 			if (client->msize == 0)
487 				fatal("IMSG_MSIZE got msize = 0");
488 
489 			break;
490 
491 		case IMSG_CLOSE:
492 			/*
493 			 * Both EVBUFFER_READ or EVBUFFER_WRITE should
494 			 * be fine.
495 			 */
496 			client_error(client->bev, EVBUFFER_READ, client);
497 			break;
498 
499 		default:
500 			log_debug("%s: unexpected imsg %d", __func__,
501 			    imsg.hdr.type);
502 			break;
503 		}
504 		imsg_free(&imsg);
505 	}
506 
507 	if (!shut)
508 		listener_imsg_event_add(iev, d);
509 	else {
510 		/* This pipe is dead.  Remove its handler */
511 		log_debug("client proc vanished");
512                 close_conn(client);
513 	}
514 }
515 
516 static int
517 listener_imsg_compose_client(struct client *client, int type,
518     uint32_t peerid, const void *data, uint16_t len)
519 {
520 	int ret;
521 
522 	if ((ret = imsg_compose(&client->iev.ibuf, type, peerid, 0, -1,
523 	    data, len)) != -1)
524 		listener_imsg_event_add(&client->iev, client);
525 
526 	return ret;
527 }
528 
529 static inline struct kd_pki_conf *
530 pki_by_name(const char *name)
531 {
532         struct kd_pki_conf *pki;
533 
534 	STAILQ_FOREACH(pki, &listener_conf->pki_head, entry) {
535 		if (!strcmp(name, pki->name))
536 			return pki;
537 	}
538 
539 	return NULL;
540 }
541 
542 static void
543 apply_config(struct kd_conf *conf)
544 {
545 	struct kd_pki_conf *pki;
546 	struct kd_listen_conf *listen;
547 	struct client *c;
548 
549 	/* drop any pre-auth inflight connections */
550 	SPLAY_FOREACH(c, clients_tree_id, &clients) {
551 		/*
552 		 * c->event is set only during the handshake and the teardown
553 		 * of the connection; c->bev is set only after auth.  Checking
554 		 * for both ensures we drop only incoming connection in the
555 		 * pre-auth state.
556 		 */
557 		if (event_pending(&c->event, EV_READ|EV_WRITE, NULL) &&
558 		    c->bev == NULL) {
559 			log_warn("closing in-flight connection due to reload");
560 			close_conn(c);
561 		}
562 	}
563 
564 	/* swap the now config with the current one */
565 	clear_config(listener_conf);
566 	listener_conf = conf;
567 
568 	/* prepare the various tls_config */
569 	STAILQ_FOREACH(pki, &listener_conf->pki_head, entry) {
570 		if ((pki->tlsconf = tls_config_new()) == NULL)
571 			fatal("tls_config_new");
572 		tls_config_verify_client_optional(pki->tlsconf);
573 		tls_config_insecure_noverifycert(pki->tlsconf);
574 		if (tls_config_set_keypair_mem(pki->tlsconf,
575 		    pki->cert, pki->certlen,
576 		    pki->key, pki->keylen) == -1)
577 			fatalx("tls_config_set_keypair_mem: %s",
578 			    tls_config_error(pki->tlsconf));
579 	}
580 
581 	/* prepare and kickoff the listeners */
582 	STAILQ_FOREACH(listen, &listener_conf->listen_head, entry) {
583 		if ((listen->ctx = tls_server()) == NULL)
584 			fatal("tls_server");
585 
586 		pki = pki_by_name(listen->pki);
587 		if (tls_configure(listen->ctx, pki->tlsconf) == -1)
588 			fatalx("tls_configure: %s",
589 			    tls_config_error(pki->tlsconf));
590 
591 		event_set(&listen->ev, listen->fd, EV_READ|EV_PERSIST,
592 		    handle_accept, listen);
593 		event_add(&listen->ev, NULL);
594 	}
595 }
596 
597 static inline void
598 yield_r(struct client *c, void (*fn)(int, short, void *))
599 {
600 	if (event_pending(&c->event, EV_WRITE|EV_READ, NULL))
601 		event_del(&c->event);
602 	event_set(&c->event, c->fd, EV_READ, fn, c);
603 	event_add(&c->event, NULL);
604 }
605 
606 static inline void
607 yield_w(struct client *c, void (*fn)(int, short, void *))
608 {
609 	if (event_pending(&c->event, EV_WRITE|EV_READ, NULL))
610 		event_del(&c->event);
611 	event_set(&c->event, c->fd, EV_WRITE, fn, c);
612 	event_add(&c->event, NULL);
613 }
614 
615 static void
616 handle_accept(int fd, short ev, void *data)
617 {
618 	static uint32_t counter;
619 	struct kd_listen_conf *listen = data;
620 	struct client *c;
621 	int s;
622 
623 	if ((s = accept(fd, NULL, NULL)) == -1) {
624 		log_warn("accept");
625 		return;
626 	}
627 
628 	c = xcalloc(1, sizeof(*c));
629 	c->msize = MSIZE9P;
630 	c->lid = listen->id;
631 	c->lflags = listen->flags;
632 	c->iev.ibuf.fd = -1;
633 
634 	if (tls_accept_socket(listen->ctx, &c->ctx, s) == -1) {
635 		log_warnx("tls_accept_socket: %s",
636 		    tls_error(listen->ctx));
637 		free(c);
638 		close(s);
639 		return;
640 	}
641 
642 	c->fd = s;
643 	c->id = counter++;
644 
645 	SPLAY_INSERT(clients_tree_id, &clients, c);
646 
647 	/* initialize the event */
648 	event_set(&c->event, c->fd, EV_READ, NULL, NULL);
649 
650 	yield_r(c, handle_handshake);
651 }
652 
653 static void
654 handle_handshake(int fd, short ev, void *data)
655 {
656 	struct client *c = data;
657 	struct kd_auth_req auth;
658 	ssize_t r;
659 	const char *hash;
660 
661 	switch (r = tls_handshake(c->ctx)) {
662 	case TLS_WANT_POLLIN:
663 		yield_r(c, handle_handshake);
664 		return;
665 	case TLS_WANT_POLLOUT:
666 		yield_w(c, handle_handshake);
667 		return;
668 	case -1:
669 		log_debug("handhsake failed: %s", tls_error(c->ctx));
670 		close_conn(c);
671 		return;
672 	}
673 
674 	if ((hash = tls_peer_cert_hash(c->ctx)) == NULL) {
675 		log_warnx("client didn't provide certificate");
676 		close_conn(c);
677 		return;
678 	}
679 
680 	memset(&auth, 0, sizeof(auth));
681 	auth.listen_id = c->lid;
682 	strlcpy(auth.hash, hash, sizeof(auth.hash));
683 	log_debug("sending hash %s", auth.hash);
684 
685 	listener_imsg_compose_main(IMSG_AUTH_TLS, c->id,
686 	    &auth, sizeof(auth));
687 }
688 
689 static void
690 client_read(struct bufferevent *bev, void *d)
691 {
692 	struct client	*client = d;
693 	struct evbuffer	*src = EVBUFFER_INPUT(bev);
694 	uint32_t	 len;
695 
696 	for (;;) {
697 		if (EVBUFFER_LENGTH(src) < 4)
698 			return;
699 
700 		memcpy(&len, EVBUFFER_DATA(src), sizeof(len));
701 		len = le32toh(len);
702 		log_debug("expecting a message %"PRIu32" bytes long "
703 		    "(of wich %zu already read)",
704 		    len, EVBUFFER_LENGTH(src));
705 
706 		if (len < HEADERSIZE) {
707 			log_warnx("invalid message size %d (too low)", len);
708 			client_error(bev, EVBUFFER_READ, client);
709 			return;
710 		}
711 
712 		if (len > client->msize) {
713 			log_warnx("incoming message bigger than msize "
714 			    "(%"PRIu32" vs %"PRIu32")", len, client->msize);
715 			client_error(bev, EVBUFFER_READ, client);
716 			return;
717 		}
718 
719 		if (len > EVBUFFER_LENGTH(src))
720 			return;
721 
722 		listener_imsg_compose_client(client, IMSG_BUF, client->id,
723 		    EVBUFFER_DATA(src), len);
724 		evbuffer_drain(src, len);
725 	}
726 }
727 
728 static void
729 client_write(struct bufferevent *bev, void *d)
730 {
731 	/*
732 	 * here we can do some fancy logic like deciding when to call
733 	 *
734 	 *	(*bev->errorcb)(bev, EVBUFFER_WRITE, bev->cbarg)
735 	 *
736 	 * to signal the end of the transaction.
737 	 */
738 
739 	return;
740 }
741 
742 static void
743 client_error(struct bufferevent *bev, short err, void *d)
744 {
745 	struct client	*client = d;
746 	struct evbuffer	*buf;
747 
748         if (err & EVBUFFER_ERROR) {
749 		if (errno == EFBIG) {
750 			bufferevent_enable(bev, EV_READ);
751 			return;
752 		}
753 		log_debug("buffer event error");
754                 close_conn(client);
755 		return;
756 	}
757 
758 	if (err & EVBUFFER_EOF) {
759                 close_conn(client);
760 		return;
761 	}
762 
763 	if (err & (EVBUFFER_READ|EVBUFFER_WRITE)) {
764 		bufferevent_disable(bev, EV_READ|EV_WRITE);
765 
766 		buf = EVBUFFER_OUTPUT(client->bev);
767 		if (EVBUFFER_LENGTH(buf) != 0) {
768 			/* finish writing all the data first */
769 			bufferevent_enable(client->bev, EV_WRITE);
770 			return;
771 		}
772 
773 		close_conn(client);
774 		return;
775 	}
776 
777 	log_warnx("unknown event error, closing client connection");
778 	close_conn(client);
779 }
780 
781 static void
782 client_tls_readcb(int fd, short event, void *d)
783 {
784 	struct bufferevent	*bufev = d;
785 	struct client		*client = bufev->cbarg;
786 	char			 buf[IBUF_READ_SIZE];
787 	int			 what = EVBUFFER_READ;
788 	int			 howmuch = IBUF_READ_SIZE;
789 	ssize_t			 ret;
790 	size_t			 len;
791 
792 	if (event == EV_TIMEOUT) {
793 		what |= EVBUFFER_TIMEOUT;
794 		goto err;
795 	}
796 
797 	if (bufev->wm_read.high != 0)
798 		howmuch = MIN(sizeof(buf), bufev->wm_read.high);
799 
800         switch (ret = tls_read(client->ctx, buf, howmuch)) {
801 	case TLS_WANT_POLLIN:
802 	case TLS_WANT_POLLOUT:
803 		goto retry;
804 	case -1:
805 		what |= EVBUFFER_ERROR;
806 		goto err;
807 	}
808 	len = ret;
809 
810 	if (len == 0) {
811 		what |= EVBUFFER_EOF;
812 		goto err;
813 	}
814 
815 	if (evbuffer_add(bufev->input, buf, len) == -1) {
816 		what |= EVBUFFER_ERROR;
817 		goto err;
818 	}
819 
820 	event_add(&bufev->ev_read, NULL);
821 
822 	len = EVBUFFER_LENGTH(bufev->input);
823 	if (bufev->wm_read.low != 0 && len < bufev->wm_read.low)
824 		return;
825 	if (bufev->wm_read.high != 0 && len > bufev->wm_read.high) {
826 		/*
827 		 * here we could implement some read pressure
828 		 * mechanism.
829 		 */
830 	}
831 
832 	if (bufev->readcb != NULL)
833 		(*bufev->readcb)(bufev, bufev->cbarg);
834 
835 	return;
836 
837 retry:
838 	event_add(&bufev->ev_read, NULL);
839 	return;
840 
841 err:
842 	(*bufev->errorcb)(bufev, what, bufev->cbarg);
843 }
844 
845 static void
846 client_tls_writecb(int fd, short event, void *d)
847 {
848 	struct bufferevent	*bufev = d;
849 	struct client		*client = bufev->cbarg;
850 	ssize_t			 ret;
851 	size_t			 len;
852 	short			 what = EVBUFFER_WRITE;
853 
854 	if (event == EV_TIMEOUT) {
855 		what |= EVBUFFER_TIMEOUT;
856 		goto err;
857 	}
858 
859 	if (EVBUFFER_LENGTH(bufev->output) != 0) {
860 		ret = tls_write(client->ctx,
861 		    EVBUFFER_DATA(bufev->output),
862 		    EVBUFFER_LENGTH(bufev->output));
863 		switch (ret) {
864 		case TLS_WANT_POLLIN:
865 		case TLS_WANT_POLLOUT:
866 			goto retry;
867 		case -1:
868 			what |= EVBUFFER_ERROR;
869 			goto err;
870 		}
871 		len = ret;
872 		evbuffer_drain(bufev->output, len);
873 	}
874 
875 	if (EVBUFFER_LENGTH(bufev->output) != 0)
876 		event_add(&bufev->ev_write, NULL);
877 
878 	if (bufev->writecb != NULL &&
879 	    EVBUFFER_LENGTH(bufev->output) <= bufev->wm_write.low)
880 		(*bufev->writecb)(bufev, bufev->cbarg);
881 	return;
882 
883 retry:
884 	event_add(&bufev->ev_write, NULL);
885 	return;
886 
887 err:
888 	(*bufev->errorcb)(bufev, what, bufev->cbarg);
889 }
890 
891 static void
892 close_conn(struct client *c)
893 {
894 	log_debug("closing connection");
895 
896 	SPLAY_REMOVE(clients_tree_id, &clients, c);
897 
898 	if (c->iev.ibuf.fd != -1) {
899 		listener_imsg_compose_client(c, IMSG_CONN_GONE, 0, NULL, 0);
900 		imsg_flush(&c->iev.ibuf);
901 		msgbuf_clear(&c->iev.ibuf.w);
902 		event_del(&c->iev.ev);
903 		close(c->iev.ibuf.fd);
904 	}
905 
906 	handle_close(c->fd, 0, c);
907 }
908 
909 static void
910 handle_close(int fd, short ev, void *d)
911 {
912 	struct client *c = d;
913 
914 	switch (tls_close(c->ctx)) {
915 	case TLS_WANT_POLLIN:
916 		yield_r(c, handle_close);
917 		return;
918 	case TLS_WANT_POLLOUT:
919 		yield_w(c, handle_close);
920 		return;
921 	}
922 
923 	event_del(&c->event);
924 	tls_free(c->ctx);
925 	close(c->fd);
926 	free(c);
927 }