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Date:: Sun May 5 09:51:27 2024 UTC
Message:: fix an issue where 'git fetch' would error or hang against gotd If Git has more than 16 have-lines to send it will send a flush-pkt followed by more have-lines. Due to a misunderstanding on my part, gotd didn't like this because it assumed that the flush-pkt terminates the list. Add a test coverage in a new file which we can use to test Git interop issues. Fixes a problem seen by Thomas Adam upon git fetch from got.g.o.
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1 /*
2  * Copyright (c) 2022, 2023 Stefan Sperling <stsp@openbsd.org>
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 <sys/types.h>
18 #include <sys/queue.h>
19 #include <sys/tree.h>
20 #include <sys/socket.h>
21 #include <sys/stat.h>
22 #include <sys/uio.h>
23 
24 #include <errno.h>
25 #include <event.h>
26 #include <limits.h>
27 #include <sha1.h>
28 #include <sha2.h>
29 #include <signal.h>
30 #include <stdint.h>
31 #include <stdio.h>
32 #include <stdlib.h>
33 #include <string.h>
34 #include <imsg.h>
35 #include <unistd.h>
36 
37 #include "got_error.h"
38 #include "got_repository.h"
39 #include "got_object.h"
40 #include "got_path.h"
41 #include "got_reference.h"
42 #include "got_opentemp.h"
43 
44 #include "got_lib_hash.h"
45 #include "got_lib_delta.h"
46 #include "got_lib_object.h"
47 #include "got_lib_object_cache.h"
48 #include "got_lib_pack.h"
49 #include "got_lib_repository.h"
50 #include "got_lib_gitproto.h"
51 
52 #include "gotd.h"
53 #include "log.h"
54 #include "session_read.h"
55 
56 enum gotd_session_read_state {
57 	GOTD_STATE_EXPECT_LIST_REFS,
58 	GOTD_STATE_EXPECT_CAPABILITIES,
59 	GOTD_STATE_EXPECT_WANT,
60 	GOTD_STATE_EXPECT_HAVE_OR_DONE,
61 	GOTD_STATE_DONE,
62 };
63 
64 static struct gotd_session_read {
65 	pid_t pid;
66 	const char *title;
67 	struct got_repository *repo;
68 	struct gotd_repo *repo_cfg;
69 	int *pack_fds;
70 	int *temp_fds;
71 	struct gotd_imsgev parent_iev;
72 	struct gotd_imsgev notifier_iev;
73 	struct timeval request_timeout;
74 	enum gotd_session_read_state state;
75 	struct gotd_imsgev repo_child_iev;
76 } gotd_session;
77 
78 static struct gotd_session_client {
79 	struct gotd_client_capability	*capabilities;
80 	size_t				 ncapa_alloc;
81 	size_t				 ncapabilities;
82 	uint32_t			 id;
83 	int				 fd;
84 	int				 delta_cache_fd;
85 	struct gotd_imsgev		 iev;
86 	struct event			 tmo;
87 	uid_t				 euid;
88 	gid_t				 egid;
89 	char				*username;
90 	char				*packfile_path;
91 	char				*packidx_path;
92 	int				 nref_updates;
93 	int				 accept_flush_pkt;
94 	int				 flush_disconnect;
95 } gotd_session_client;
96 
97 static void session_read_shutdown(void);
98 
99 static void
100 disconnect(struct gotd_session_client *client)
101 {
102 	log_debug("uid %d: disconnecting", client->euid);
103 
104 	if (gotd_imsg_compose_event(&gotd_session.parent_iev,
105 	    GOTD_IMSG_DISCONNECT, PROC_SESSION_READ, -1, NULL, 0) == -1)
106 		log_warn("imsg compose DISCONNECT");
107 
108 	imsg_clear(&gotd_session.repo_child_iev.ibuf);
109 	event_del(&gotd_session.repo_child_iev.ev);
110 	evtimer_del(&client->tmo);
111 	close(client->fd);
112 	if (client->delta_cache_fd != -1)
113 		close(client->delta_cache_fd);
114 	if (client->packfile_path) {
115 		if (unlink(client->packfile_path) == -1 && errno != ENOENT)
116 			log_warn("unlink %s: ", client->packfile_path);
117 		free(client->packfile_path);
118 	}
119 	if (client->packidx_path) {
120 		if (unlink(client->packidx_path) == -1 && errno != ENOENT)
121 			log_warn("unlink %s: ", client->packidx_path);
122 		free(client->packidx_path);
123 	}
124 	free(client->capabilities);
125 
126 	session_read_shutdown();
127 }
128 
129 static void
130 disconnect_on_error(struct gotd_session_client *client,
131     const struct got_error *err)
132 {
133 	struct imsgbuf ibuf;
134 
135 	if (err->code != GOT_ERR_EOF) {
136 		log_warnx("uid %d: %s", client->euid, err->msg);
137 		imsg_init(&ibuf, client->fd);
138 		gotd_imsg_send_error(&ibuf, 0, PROC_SESSION_READ, err);
139 		imsg_clear(&ibuf);
140 	}
141 
142 	disconnect(client);
143 }
144 
145 static void
146 gotd_request_timeout(int fd, short events, void *arg)
147 {
148 	struct gotd_session_client *client = arg;
149 
150 	log_warnx("disconnecting uid %d due to timeout", client->euid);
151 	disconnect(client);
152 }
153 
154 static void
155 session_read_sighdlr(int sig, short event, void *arg)
156 {
157 	/*
158 	 * Normal signal handler rules don't apply because libevent
159 	 * decouples for us.
160 	 */
161 
162 	switch (sig) {
163 	case SIGHUP:
164 		log_info("%s: ignoring SIGHUP", __func__);
165 		break;
166 	case SIGUSR1:
167 		log_info("%s: ignoring SIGUSR1", __func__);
168 		break;
169 	case SIGTERM:
170 	case SIGINT:
171 		session_read_shutdown();
172 		/* NOTREACHED */
173 		break;
174 	default:
175 		fatalx("unexpected signal");
176 	}
177 }
178 
179 static const struct got_error *
180 recv_packfile_done(struct imsg *imsg)
181 {
182 	size_t datalen;
183 
184 	log_debug("packfile-done received");
185 
186 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
187 	if (datalen != 0)
188 		return got_error(GOT_ERR_PRIVSEP_LEN);
189 
190 	return NULL;
191 }
192 
193 static void
194 session_dispatch_repo_child(int fd, short event, void *arg)
195 {
196 	struct gotd_imsgev *iev = arg;
197 	struct imsgbuf *ibuf = &iev->ibuf;
198 	struct gotd_session_client *client = &gotd_session_client;
199 	ssize_t n;
200 	int shut = 0;
201 	struct imsg imsg;
202 
203 	if (event & EV_READ) {
204 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
205 			fatal("imsg_read error");
206 		if (n == 0) {
207 			/* Connection closed. */
208 			shut = 1;
209 			goto done;
210 		}
211 	}
212 
213 	if (event & EV_WRITE) {
214 		n = msgbuf_write(&ibuf->w);
215 		if (n == -1 && errno != EAGAIN)
216 			fatal("msgbuf_write");
217 		if (n == 0) {
218 			/* Connection closed. */
219 			shut = 1;
220 			goto done;
221 		}
222 	}
223 
224 	for (;;) {
225 		const struct got_error *err = NULL;
226 		uint32_t client_id = 0;
227 		int do_disconnect = 0;
228 
229 		if ((n = imsg_get(ibuf, &imsg)) == -1)
230 			fatal("%s: imsg_get error", __func__);
231 		if (n == 0)	/* No more messages. */
232 			break;
233 
234 		switch (imsg.hdr.type) {
235 		case GOTD_IMSG_ERROR:
236 			do_disconnect = 1;
237 			err = gotd_imsg_recv_error(&client_id, &imsg);
238 			break;
239 		case GOTD_IMSG_PACKFILE_DONE:
240 			do_disconnect = 1;
241 			err = recv_packfile_done(&imsg);
242 			break;
243 		default:
244 			log_debug("unexpected imsg %d", imsg.hdr.type);
245 			break;
246 		}
247 
248 		if (do_disconnect) {
249 			if (err)
250 				disconnect_on_error(client, err);
251 			else
252 				disconnect(client);
253 		} else {
254 			if (err)
255 				log_warnx("uid %d: %s", client->euid, err->msg);
256 		}
257 		imsg_free(&imsg);
258 	}
259 done:
260 	if (!shut) {
261 		gotd_imsg_event_add(iev);
262 	} else {
263 		/* This pipe is dead. Remove its event handler */
264 		event_del(&iev->ev);
265 		event_loopexit(NULL);
266 	}
267 }
268 
269 static const struct got_error *
270 recv_capabilities(struct gotd_session_client *client, struct imsg *imsg)
271 {
272 	struct gotd_imsg_capabilities icapas;
273 	size_t datalen;
274 
275 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
276 	if (datalen != sizeof(icapas))
277 		return got_error(GOT_ERR_PRIVSEP_LEN);
278 	memcpy(&icapas, imsg->data, sizeof(icapas));
279 
280 	client->ncapa_alloc = icapas.ncapabilities;
281 	client->capabilities = calloc(client->ncapa_alloc,
282 	    sizeof(*client->capabilities));
283 	if (client->capabilities == NULL) {
284 		client->ncapa_alloc = 0;
285 		return got_error_from_errno("calloc");
286 	}
287 
288 	log_debug("expecting %zu capabilities from uid %d",
289 	    client->ncapa_alloc, client->euid);
290 	return NULL;
291 }
292 
293 static const struct got_error *
294 recv_capability(struct gotd_session_client *client, struct imsg *imsg)
295 {
296 	struct gotd_imsg_capability icapa;
297 	struct gotd_client_capability *capa;
298 	size_t datalen;
299 	char *key, *value = NULL;
300 
301 	if (client->capabilities == NULL ||
302 	    client->ncapabilities >= client->ncapa_alloc) {
303 		return got_error_msg(GOT_ERR_BAD_REQUEST,
304 		    "unexpected capability received");
305 	}
306 
307 	memset(&icapa, 0, sizeof(icapa));
308 
309 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
310 	if (datalen < sizeof(icapa))
311 		return got_error(GOT_ERR_PRIVSEP_LEN);
312 	memcpy(&icapa, imsg->data, sizeof(icapa));
313 
314 	if (datalen != sizeof(icapa) + icapa.key_len + icapa.value_len)
315 		return got_error(GOT_ERR_PRIVSEP_LEN);
316 
317 	key = strndup(imsg->data + sizeof(icapa), icapa.key_len);
318 	if (key == NULL)
319 		return got_error_from_errno("strndup");
320 	if (icapa.value_len > 0) {
321 		value = strndup(imsg->data + sizeof(icapa) + icapa.key_len,
322 		    icapa.value_len);
323 		if (value == NULL) {
324 			free(key);
325 			return got_error_from_errno("strndup");
326 		}
327 	}
328 
329 	capa = &client->capabilities[client->ncapabilities++];
330 	capa->key = key;
331 	capa->value = value;
332 
333 	if (value)
334 		log_debug("uid %d: capability %s=%s", client->euid, key, value);
335 	else
336 		log_debug("uid %d: capability %s", client->euid, key);
337 
338 	return NULL;
339 }
340 
341 static const struct got_error *
342 forward_want(struct gotd_session_client *client, struct imsg *imsg)
343 {
344 	struct gotd_imsg_want ireq;
345 	struct gotd_imsg_want iwant;
346 	size_t datalen;
347 
348 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
349 	if (datalen != sizeof(ireq))
350 		return got_error(GOT_ERR_PRIVSEP_LEN);
351 
352 	memcpy(&ireq, imsg->data, datalen);
353 
354 	memset(&iwant, 0, sizeof(iwant));
355 	memcpy(iwant.object_id, ireq.object_id, SHA1_DIGEST_LENGTH);
356 
357 	if (gotd_imsg_compose_event(&gotd_session.repo_child_iev,
358 	    GOTD_IMSG_WANT, PROC_SESSION_READ, -1,
359 	    &iwant, sizeof(iwant)) == -1)
360 		return got_error_from_errno("imsg compose WANT");
361 
362 	return NULL;
363 }
364 
365 static const struct got_error *
366 forward_have(struct gotd_session_client *client, struct imsg *imsg)
367 {
368 	struct gotd_imsg_have ireq;
369 	struct gotd_imsg_have ihave;
370 	size_t datalen;
371 
372 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
373 	if (datalen != sizeof(ireq))
374 		return got_error(GOT_ERR_PRIVSEP_LEN);
375 
376 	memcpy(&ireq, imsg->data, datalen);
377 
378 	memset(&ihave, 0, sizeof(ihave));
379 	memcpy(ihave.object_id, ireq.object_id, SHA1_DIGEST_LENGTH);
380 
381 	if (gotd_imsg_compose_event(&gotd_session.repo_child_iev,
382 	    GOTD_IMSG_HAVE, PROC_SESSION_READ, -1,
383 	    &ihave, sizeof(ihave)) == -1)
384 		return got_error_from_errno("imsg compose HAVE");
385 
386 	return NULL;
387 }
388 
389 static int
390 client_has_capability(struct gotd_session_client *client, const char *capastr)
391 {
392 	struct gotd_client_capability *capa;
393 	size_t i;
394 
395 	if (client->ncapabilities == 0)
396 		return 0;
397 
398 	for (i = 0; i < client->ncapabilities; i++) {
399 		capa = &client->capabilities[i];
400 		if (strcmp(capa->key, capastr) == 0)
401 			return 1;
402 	}
403 
404 	return 0;
405 }
406 
407 static const struct got_error *
408 send_packfile(struct gotd_session_client *client)
409 {
410 	const struct got_error *err = NULL;
411 	struct gotd_imsg_send_packfile ipack;
412 	int pipe[2];
413 
414 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, pipe) == -1)
415 		return got_error_from_errno("socketpair");
416 
417 	memset(&ipack, 0, sizeof(ipack));
418 
419 	if (client_has_capability(client, GOT_CAPA_SIDE_BAND_64K))
420 		ipack.report_progress = 1;
421 
422 	client->delta_cache_fd = got_opentempfd();
423 	if (client->delta_cache_fd == -1)
424 		return got_error_from_errno("got_opentempfd");
425 
426 	if (gotd_imsg_compose_event(&gotd_session.repo_child_iev,
427 	    GOTD_IMSG_SEND_PACKFILE, PROC_GOTD, client->delta_cache_fd,
428 	    &ipack, sizeof(ipack)) == -1) {
429 		err = got_error_from_errno("imsg compose SEND_PACKFILE");
430 		close(pipe[0]);
431 		close(pipe[1]);
432 		return err;
433 	}
434 
435 	/* Send pack pipe end 0 to repo child process. */
436 	if (gotd_imsg_compose_event(&gotd_session.repo_child_iev,
437 	    GOTD_IMSG_PACKFILE_PIPE, PROC_GOTD, pipe[0], NULL, 0) == -1) {
438 		err = got_error_from_errno("imsg compose PACKFILE_PIPE");
439 		close(pipe[1]);
440 		return err;
441 	}
442 
443 	/* Send pack pipe end 1 to gotsh(1) (expects just an fd, no data). */
444 	if (gotd_imsg_compose_event(&client->iev,
445 	    GOTD_IMSG_PACKFILE_PIPE, PROC_GOTD, pipe[1], NULL, 0) == -1)
446 		err = got_error_from_errno("imsg compose PACKFILE_PIPE");
447 
448 	return err;
449 }
450 
451 static void
452 session_dispatch_client(int fd, short events, void *arg)
453 {
454 	struct gotd_imsgev *iev = arg;
455 	struct imsgbuf *ibuf = &iev->ibuf;
456 	struct gotd_session_client *client = &gotd_session_client;
457 	const struct got_error *err = NULL;
458 	struct imsg imsg;
459 	ssize_t n;
460 
461 	if (events & EV_WRITE) {
462 		while (ibuf->w.queued) {
463 			n = msgbuf_write(&ibuf->w);
464 			if (n == -1 && errno != EAGAIN) {
465 				err = got_error_from_errno("imsg_flush");
466 				disconnect_on_error(client, err);
467 				return;
468 			}
469 			if (n == 0) {
470 				/* Connection closed. */
471 				err = got_error(GOT_ERR_EOF);
472 				disconnect_on_error(client, err);
473 				return;
474 			}
475 		}
476 
477 		if (client->flush_disconnect) {
478 			disconnect(client);
479 			return;
480 		}
481 	}
482 
483 	if ((events & EV_READ) == 0)
484 		return;
485 
486 	memset(&imsg, 0, sizeof(imsg));
487 
488 	while (err == NULL) {
489 		err = gotd_imsg_recv(&imsg, ibuf, 0);
490 		if (err) {
491 			if (err->code == GOT_ERR_PRIVSEP_READ)
492 				err = NULL;
493 			else if (err->code == GOT_ERR_EOF &&
494 			    gotd_session.state ==
495 			    GOTD_STATE_EXPECT_CAPABILITIES) {
496 				/*
497 				 * The client has closed its socket before
498 				 * sending its capability announcement.
499 				 * This can happen when Git clients have
500 				 * no ref-updates to send.
501 				 */
502 				disconnect_on_error(client, err);
503 				return;
504 			}
505 			break;
506 		}
507 
508 		evtimer_del(&client->tmo);
509 
510 		switch (imsg.hdr.type) {
511 		case GOTD_IMSG_CAPABILITIES:
512 			if (gotd_session.state !=
513 			    GOTD_STATE_EXPECT_CAPABILITIES) {
514 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
515 				    "unexpected capabilities received");
516 				break;
517 			}
518 			log_debug("receiving capabilities from uid %d",
519 			    client->euid);
520 			err = recv_capabilities(client, &imsg);
521 			break;
522 		case GOTD_IMSG_CAPABILITY:
523 			if (gotd_session.state != GOTD_STATE_EXPECT_CAPABILITIES) {
524 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
525 				    "unexpected capability received");
526 				break;
527 			}
528 			err = recv_capability(client, &imsg);
529 			if (err || client->ncapabilities < client->ncapa_alloc)
530 				break;
531 			gotd_session.state = GOTD_STATE_EXPECT_WANT;
532 			client->accept_flush_pkt = 1;
533 			log_debug("uid %d: expecting want-lines", client->euid);
534 			break;
535 		case GOTD_IMSG_WANT:
536 			if (gotd_session.state != GOTD_STATE_EXPECT_WANT) {
537 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
538 				    "unexpected want-line received");
539 				break;
540 			}
541 			log_debug("received want-line from uid %d",
542 			    client->euid);
543 			client->accept_flush_pkt = 1;
544 			err = forward_want(client, &imsg);
545 			break;
546 		case GOTD_IMSG_HAVE:
547 			if (gotd_session.state !=
548 			    GOTD_STATE_EXPECT_HAVE_OR_DONE) {
549 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
550 				    "unexpected have-line received");
551 				break;
552 			}
553 			log_debug("received have-line from uid %d",
554 			    client->euid);
555 			err = forward_have(client, &imsg);
556 			if (err)
557 				break;
558 			client->accept_flush_pkt = 1;
559 			break;
560 		case GOTD_IMSG_FLUSH:
561 			if (gotd_session.state != GOTD_STATE_EXPECT_WANT && 
562 			    gotd_session.state !=
563 			    GOTD_STATE_EXPECT_HAVE_OR_DONE) {
564 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
565 				    "unexpected flush-pkt received");
566 				break;
567 			}
568 			if (!client->accept_flush_pkt) {
569 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
570 				    "unexpected flush-pkt received");
571 				break;
572 			}
573 
574 			/*
575 			 * Accept just one flush packet at a time.
576 			 * Future client state transitions will set this flag
577 			 * again if another flush packet is expected.
578 			 */
579 			client->accept_flush_pkt = 0;
580 
581 			log_debug("received flush-pkt from uid %d",
582 			    client->euid);
583 			if (gotd_session.state == GOTD_STATE_EXPECT_WANT) {
584 				gotd_session.state =
585 				    GOTD_STATE_EXPECT_HAVE_OR_DONE;
586 				log_debug("uid %d: expecting have-lines "
587 				    "or 'done'", client->euid);
588 			} else if (gotd_session.state ==
589 			    GOTD_STATE_EXPECT_HAVE_OR_DONE) {
590 				client->accept_flush_pkt = 1;
591 				log_debug("uid %d: expecting more have-lines "
592 				    "or 'done'", client->euid);
593 			} else if (gotd_session.state !=
594 			    GOTD_STATE_EXPECT_HAVE_OR_DONE) {
595 				/* should not happen, see above */
596 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
597 				    "unexpected client state");
598 				break;
599 			}
600 			break;
601 		case GOTD_IMSG_DONE:
602 			if (gotd_session.state !=
603 			    GOTD_STATE_EXPECT_HAVE_OR_DONE) {
604 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
605 				    "unexpected flush-pkt received");
606 				break;
607 			}
608 			log_debug("received 'done' from uid %d", client->euid);
609 			gotd_session.state = GOTD_STATE_DONE;
610 			client->accept_flush_pkt = 1;
611 			err = send_packfile(client);
612 			break;
613 		default:
614 			log_debug("unexpected imsg %d", imsg.hdr.type);
615 			err = got_error(GOT_ERR_PRIVSEP_MSG);
616 			break;
617 		}
618 
619 		imsg_free(&imsg);
620 	}
621 
622 	if (err) {
623 		if (err->code != GOT_ERR_EOF)
624 			disconnect_on_error(client, err);
625 	} else {
626 		gotd_imsg_event_add(iev);
627 		evtimer_add(&client->tmo, &gotd_session.request_timeout);
628 	}
629 }
630 
631 static const struct got_error *
632 list_refs_request(void)
633 {
634 	static const struct got_error *err;
635 	struct gotd_session_client *client = &gotd_session_client;
636 	struct gotd_imsgev *iev = &gotd_session.repo_child_iev;
637 	int fd;
638 
639 	if (gotd_session.state != GOTD_STATE_EXPECT_LIST_REFS)
640 		return got_error(GOT_ERR_PRIVSEP_MSG);
641 
642 	fd = dup(client->fd);
643 	if (fd == -1)
644 		return got_error_from_errno("dup");
645 
646 	if (gotd_imsg_compose_event(iev, GOTD_IMSG_LIST_REFS_INTERNAL,
647 	    PROC_SESSION_READ, fd, NULL, 0) == -1) {
648 		err = got_error_from_errno("imsg compose LIST_REFS_INTERNAL");
649 		close(fd);
650 		return err;
651 	}
652 
653 	gotd_session.state = GOTD_STATE_EXPECT_CAPABILITIES;
654 	log_debug("uid %d: expecting capabilities", client->euid);
655 	return NULL;
656 }
657 
658 static const struct got_error *
659 recv_connect(struct imsg *imsg)
660 {
661 	struct gotd_session_client *client = &gotd_session_client;
662 	struct gotd_imsg_connect iconnect;
663 	size_t datalen;
664 
665 	if (gotd_session.state != GOTD_STATE_EXPECT_LIST_REFS)
666 		return got_error(GOT_ERR_PRIVSEP_MSG);
667 
668 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
669 	if (datalen < sizeof(iconnect))
670 		return got_error(GOT_ERR_PRIVSEP_LEN);
671 	memcpy(&iconnect, imsg->data, sizeof(iconnect));
672 	if (iconnect.username_len == 0 ||
673 	    datalen != sizeof(iconnect) + iconnect.username_len)
674 		return got_error(GOT_ERR_PRIVSEP_LEN);
675 
676 	client->euid = iconnect.euid;
677 	client->egid = iconnect.egid;
678 	client->fd = imsg_get_fd(imsg);
679 	if (client->fd == -1)
680 		return got_error(GOT_ERR_PRIVSEP_NO_FD);
681 
682 	client->username = strndup(imsg->data + sizeof(iconnect),
683 	    iconnect.username_len);
684 	if (client->username == NULL)
685 		return got_error_from_errno("strndup");
686 
687 	imsg_init(&client->iev.ibuf, client->fd);
688 	client->iev.handler = session_dispatch_client;
689 	client->iev.events = EV_READ;
690 	client->iev.handler_arg = NULL;
691 	event_set(&client->iev.ev, client->iev.ibuf.fd, EV_READ,
692 	    session_dispatch_client, &client->iev);
693 	gotd_imsg_event_add(&client->iev);
694 	evtimer_set(&client->tmo, gotd_request_timeout, client);
695 	evtimer_add(&client->tmo, &gotd_session.request_timeout);
696 
697 	return NULL;
698 }
699 
700 static const struct got_error *
701 recv_repo_child(struct imsg *imsg)
702 {
703 	struct gotd_imsg_connect_repo_child ichild;
704 	struct gotd_session_client *client = &gotd_session_client;
705 	size_t datalen;
706 	int fd;
707 
708 	if (gotd_session.state != GOTD_STATE_EXPECT_LIST_REFS)
709 		return got_error(GOT_ERR_PRIVSEP_MSG);
710 
711 	/* We should already have received a pipe to the listener. */
712 	if (client->fd == -1)
713 		return got_error(GOT_ERR_PRIVSEP_MSG);
714 
715 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
716 	if (datalen != sizeof(ichild))
717 		return got_error(GOT_ERR_PRIVSEP_LEN);
718 
719 	memcpy(&ichild, imsg->data, sizeof(ichild));
720 
721 	if (ichild.proc_id != PROC_REPO_READ)
722 		return got_error_msg(GOT_ERR_PRIVSEP_MSG,
723 		    "bad child process type");
724 
725 	fd = imsg_get_fd(imsg);
726 	if (fd == -1)
727 		return got_error(GOT_ERR_PRIVSEP_NO_FD);
728 
729 	imsg_init(&gotd_session.repo_child_iev.ibuf, fd);
730 	gotd_session.repo_child_iev.handler = session_dispatch_repo_child;
731 	gotd_session.repo_child_iev.events = EV_READ;
732 	gotd_session.repo_child_iev.handler_arg = NULL;
733 	event_set(&gotd_session.repo_child_iev.ev,
734 	    gotd_session.repo_child_iev.ibuf.fd, EV_READ,
735 	    session_dispatch_repo_child, &gotd_session.repo_child_iev);
736 	gotd_imsg_event_add(&gotd_session.repo_child_iev);
737 
738 	/* The "recvfd" pledge promise is no longer needed. */
739 	if (pledge("stdio rpath wpath cpath sendfd fattr flock", NULL) == -1)
740 		fatal("pledge");
741 
742 	return NULL;
743 }
744 
745 static void
746 session_dispatch(int fd, short event, void *arg)
747 {
748 	struct gotd_imsgev *iev = arg;
749 	struct imsgbuf *ibuf = &iev->ibuf;
750 	struct gotd_session_client *client = &gotd_session_client;
751 	ssize_t n;
752 	int shut = 0;
753 	struct imsg imsg;
754 
755 	if (event & EV_READ) {
756 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
757 			fatal("imsg_read error");
758 		if (n == 0) {
759 			/* Connection closed. */
760 			shut = 1;
761 			goto done;
762 		}
763 	}
764 
765 	if (event & EV_WRITE) {
766 		n = msgbuf_write(&ibuf->w);
767 		if (n == -1 && errno != EAGAIN)
768 			fatal("msgbuf_write");
769 		if (n == 0) {
770 			/* Connection closed. */
771 			shut = 1;
772 			goto done;
773 		}
774 	}
775 
776 	for (;;) {
777 		const struct got_error *err = NULL;
778 		uint32_t client_id = 0;
779 		int do_disconnect = 0, do_list_refs = 0;
780 
781 		if ((n = imsg_get(ibuf, &imsg)) == -1)
782 			fatal("%s: imsg_get error", __func__);
783 		if (n == 0)	/* No more messages. */
784 			break;
785 
786 		switch (imsg.hdr.type) {
787 		case GOTD_IMSG_ERROR:
788 			do_disconnect = 1;
789 			err = gotd_imsg_recv_error(&client_id, &imsg);
790 			break;
791 		case GOTD_IMSG_CONNECT:
792 			err = recv_connect(&imsg);
793 			break;
794 		case GOTD_IMSG_DISCONNECT:
795 			do_disconnect = 1;
796 			break;
797 		case GOTD_IMSG_CONNECT_REPO_CHILD:
798 			err = recv_repo_child(&imsg);
799 			if (err)
800 				break;
801 			do_list_refs = 1;
802 			break;
803 		default:
804 			log_debug("unexpected imsg %d", imsg.hdr.type);
805 			break;
806 		}
807 		imsg_free(&imsg);
808 
809 		if (do_disconnect) {
810 			if (err)
811 				disconnect_on_error(client, err);
812 			else
813 				disconnect(client);
814 		} else if (do_list_refs)
815 			err = list_refs_request();
816 
817 		if (err)
818 			log_warnx("uid %d: %s", client->euid, err->msg);
819 	}
820 done:
821 	if (!shut) {
822 		gotd_imsg_event_add(iev);
823 	} else {
824 		/* This pipe is dead. Remove its event handler */
825 		event_del(&iev->ev);
826 		event_loopexit(NULL);
827 	}
828 }
829 
830 void
831 session_read_main(const char *title, const char *repo_path,
832     int *pack_fds, int *temp_fds, struct timeval *request_timeout,
833     struct gotd_repo *repo_cfg)
834 {
835 	const struct got_error *err = NULL;
836 	struct event evsigint, evsigterm, evsighup, evsigusr1;
837 
838 	gotd_session.title = title;
839 	gotd_session.pid = getpid();
840 	gotd_session.pack_fds = pack_fds;
841 	gotd_session.temp_fds = temp_fds;
842 	memcpy(&gotd_session.request_timeout, request_timeout,
843 	    sizeof(gotd_session.request_timeout));
844 	gotd_session.repo_cfg = repo_cfg;
845 
846 	imsg_init(&gotd_session.notifier_iev.ibuf, -1);
847 
848 	err = got_repo_open(&gotd_session.repo, repo_path, NULL, pack_fds);
849 	if (err)
850 		goto done;
851 	if (!got_repo_is_bare(gotd_session.repo)) {
852 		err = got_error_msg(GOT_ERR_NOT_GIT_REPO,
853 		    "bare git repository required");
854 		goto done;
855 	}
856 
857 	got_repo_temp_fds_set(gotd_session.repo, temp_fds);
858 
859 	signal_set(&evsigint, SIGINT, session_read_sighdlr, NULL);
860 	signal_set(&evsigterm, SIGTERM, session_read_sighdlr, NULL);
861 	signal_set(&evsighup, SIGHUP, session_read_sighdlr, NULL);
862 	signal_set(&evsigusr1, SIGUSR1, session_read_sighdlr, NULL);
863 	signal(SIGPIPE, SIG_IGN);
864 
865 	signal_add(&evsigint, NULL);
866 	signal_add(&evsigterm, NULL);
867 	signal_add(&evsighup, NULL);
868 	signal_add(&evsigusr1, NULL);
869 
870 	gotd_session.state = GOTD_STATE_EXPECT_LIST_REFS;
871 
872 	gotd_session_client.fd = -1;
873 	gotd_session_client.nref_updates = -1;
874 	gotd_session_client.delta_cache_fd = -1;
875 	gotd_session_client.accept_flush_pkt = 1;
876 
877 	imsg_init(&gotd_session.parent_iev.ibuf, GOTD_FILENO_MSG_PIPE);
878 	gotd_session.parent_iev.handler = session_dispatch;
879 	gotd_session.parent_iev.events = EV_READ;
880 	gotd_session.parent_iev.handler_arg = NULL;
881 	event_set(&gotd_session.parent_iev.ev, gotd_session.parent_iev.ibuf.fd,
882 	    EV_READ, session_dispatch, &gotd_session.parent_iev);
883 	if (gotd_imsg_compose_event(&gotd_session.parent_iev,
884 	    GOTD_IMSG_CLIENT_SESSION_READY, PROC_SESSION_READ,
885 	    -1, NULL, 0) == -1) {
886 		err = got_error_from_errno("imsg compose CLIENT_SESSION_READY");
887 		goto done;
888 	}
889 
890 	event_dispatch();
891 done:
892 	if (err)
893 		log_warnx("%s: %s", title, err->msg);
894 	session_read_shutdown();
895 }
896 
897 static void
898 session_read_shutdown(void)
899 {
900 	log_debug("%s: shutting down", gotd_session.title);
901 
902 	if (gotd_session.repo)
903 		got_repo_close(gotd_session.repo);
904 	got_repo_pack_fds_close(gotd_session.pack_fds);
905 	got_repo_temp_fds_close(gotd_session.temp_fds);
906 	free(gotd_session_client.username);
907 	exit(0);
908 }