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Date:: Mon Apr 29 12:23:45 2024 UTC
Message:: expose authenticated gotd user account in HTTP notifications ok op@
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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 "got_compat.h"
18 
19 #include <sys/types.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 <signal.h>
28 #include <stdint.h>
29 #include <stdio.h>
30 #include <stdlib.h>
31 #include <string.h>
32 #include <imsg.h>
33 #include <unistd.h>
34 
35 #include "got_compat.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_write.h"
55 
56 struct gotd_session_notif {
57 	STAILQ_ENTRY(gotd_session_notif) entry;
58 	int fd;
59 	enum gotd_notification_action action;
60 	char *refname;
61 	struct got_object_id old_id;
62 	struct got_object_id new_id;
63 };
64 STAILQ_HEAD(gotd_session_notifications, gotd_session_notif) notifications;
65 
66 enum gotd_session_write_state {
67 	GOTD_STATE_EXPECT_LIST_REFS,
68 	GOTD_STATE_EXPECT_CAPABILITIES,
69 	GOTD_STATE_EXPECT_REF_UPDATE,
70 	GOTD_STATE_EXPECT_MORE_REF_UPDATES,
71 	GOTD_STATE_EXPECT_PACKFILE,
72 	GOTD_STATE_NOTIFY,
73 };
74 
75 static struct gotd_session_write {
76 	pid_t pid;
77 	const char *title;
78 	struct got_repository *repo;
79 	struct gotd_repo *repo_cfg;
80 	int *pack_fds;
81 	int *temp_fds;
82 	struct gotd_imsgev parent_iev;
83 	struct gotd_imsgev notifier_iev;
84 	struct timeval request_timeout;
85 	enum gotd_session_write_state state;
86 	struct gotd_imsgev repo_child_iev;
87 } gotd_session;
88 
89 static struct gotd_session_client {
90 	struct gotd_client_capability	*capabilities;
91 	size_t				 ncapa_alloc;
92 	size_t				 ncapabilities;
93 	uint32_t			 id;
94 	int				 fd;
95 	int				 delta_cache_fd;
96 	struct gotd_imsgev		 iev;
97 	struct event			 tmo;
98 	uid_t				 euid;
99 	gid_t				 egid;
100 	char				*username;
101 	char				*packfile_path;
102 	char				*packidx_path;
103 	int				 nref_updates;
104 	int				 accept_flush_pkt;
105 	int				 flush_disconnect;
106 } gotd_session_client;
107 
108 static void session_write_shutdown(void);
109 
110 static void
111 disconnect(struct gotd_session_client *client)
112 {
113 	log_debug("uid %d: disconnecting", client->euid);
114 
115 	if (gotd_imsg_compose_event(&gotd_session.parent_iev,
116 	    GOTD_IMSG_DISCONNECT, PROC_SESSION_WRITE, -1, NULL, 0) == -1)
117 		log_warn("imsg compose DISCONNECT");
118 
119 	imsg_clear(&gotd_session.repo_child_iev.ibuf);
120 	event_del(&gotd_session.repo_child_iev.ev);
121 	evtimer_del(&client->tmo);
122 	close(client->fd);
123 	if (client->delta_cache_fd != -1)
124 		close(client->delta_cache_fd);
125 	if (client->packfile_path) {
126 		if (unlink(client->packfile_path) == -1 && errno != ENOENT)
127 			log_warn("unlink %s: ", client->packfile_path);
128 		free(client->packfile_path);
129 	}
130 	if (client->packidx_path) {
131 		if (unlink(client->packidx_path) == -1 && errno != ENOENT)
132 			log_warn("unlink %s: ", client->packidx_path);
133 		free(client->packidx_path);
134 	}
135 	free(client->capabilities);
136 
137 	session_write_shutdown();
138 }
139 
140 static void
141 disconnect_on_error(struct gotd_session_client *client,
142     const struct got_error *err)
143 {
144 	struct imsgbuf ibuf;
145 
146 	if (err->code != GOT_ERR_EOF) {
147 		log_warnx("uid %d: %s", client->euid, err->msg);
148 		imsg_init(&ibuf, client->fd);
149 		gotd_imsg_send_error(&ibuf, 0, PROC_SESSION_WRITE, err);
150 		imsg_clear(&ibuf);
151 	}
152 
153 	disconnect(client);
154 }
155 
156 static void
157 gotd_request_timeout(int fd, short events, void *arg)
158 {
159 	struct gotd_session_client *client = arg;
160 
161 	log_debug("disconnecting uid %d due to timeout", client->euid);
162 	disconnect(client);
163 }
164 
165 static void
166 session_write_sighdlr(int sig, short event, void *arg)
167 {
168 	/*
169 	 * Normal signal handler rules don't apply because libevent
170 	 * decouples for us.
171 	 */
172 
173 	switch (sig) {
174 	case SIGHUP:
175 		log_info("%s: ignoring SIGHUP", __func__);
176 		break;
177 	case SIGUSR1:
178 		log_info("%s: ignoring SIGUSR1", __func__);
179 		break;
180 	case SIGTERM:
181 	case SIGINT:
182 		session_write_shutdown();
183 		/* NOTREACHED */
184 		break;
185 	default:
186 		fatalx("unexpected signal");
187 	}
188 }
189 
190 static const struct got_error *
191 recv_packfile_install(struct imsg *imsg)
192 {
193 	struct gotd_imsg_packfile_install inst;
194 	size_t datalen;
195 
196 	log_debug("packfile-install received");
197 
198 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
199 	if (datalen != sizeof(inst))
200 		return got_error(GOT_ERR_PRIVSEP_LEN);
201 	memcpy(&inst, imsg->data, sizeof(inst));
202 
203 	return NULL;
204 }
205 
206 static const struct got_error *
207 recv_ref_updates_start(struct imsg *imsg)
208 {
209 	struct gotd_imsg_ref_updates_start istart;
210 	size_t datalen;
211 
212 	log_debug("ref-updates-start received");
213 
214 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
215 	if (datalen != sizeof(istart))
216 		return got_error(GOT_ERR_PRIVSEP_LEN);
217 	memcpy(&istart, imsg->data, sizeof(istart));
218 
219 	return NULL;
220 }
221 
222 static const struct got_error *
223 recv_ref_update(struct imsg *imsg)
224 {
225 	struct gotd_imsg_ref_update iref;
226 	size_t datalen;
227 
228 	log_debug("ref-update received");
229 
230 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
231 	if (datalen < sizeof(iref))
232 		return got_error(GOT_ERR_PRIVSEP_LEN);
233 	memcpy(&iref, imsg->data, sizeof(iref));
234 
235 	return NULL;
236 }
237 
238 static const struct got_error *
239 send_ref_update_ok(struct gotd_session_client *client,
240     struct gotd_imsg_ref_update *iref, const char *refname)
241 {
242 	struct gotd_imsg_ref_update_ok iok;
243 	struct gotd_imsgev *iev = &client->iev;
244 	struct ibuf *wbuf;
245 	size_t len;
246 
247 	memset(&iok, 0, sizeof(iok));
248 	memcpy(iok.old_id, iref->old_id, SHA1_DIGEST_LENGTH);
249 	memcpy(iok.new_id, iref->new_id, SHA1_DIGEST_LENGTH);
250 	iok.name_len = strlen(refname);
251 
252 	len = sizeof(iok) + iok.name_len;
253 	wbuf = imsg_create(&iev->ibuf, GOTD_IMSG_REF_UPDATE_OK,
254 	    PROC_SESSION_WRITE, gotd_session.pid, len);
255 	if (wbuf == NULL)
256 		return got_error_from_errno("imsg_create REF_UPDATE_OK");
257 
258 	if (imsg_add(wbuf, &iok, sizeof(iok)) == -1)
259 		return got_error_from_errno("imsg_add REF_UPDATE_OK");
260 	if (imsg_add(wbuf, refname, iok.name_len) == -1)
261 		return got_error_from_errno("imsg_add REF_UPDATE_OK");
262 
263 	imsg_close(&iev->ibuf, wbuf);
264 	gotd_imsg_event_add(iev);
265 	return NULL;
266 }
267 
268 static void
269 send_refs_updated(struct gotd_session_client *client)
270 {
271 	if (gotd_imsg_compose_event(&client->iev, GOTD_IMSG_REFS_UPDATED,
272 	    PROC_SESSION_WRITE, -1, NULL, 0) == -1)
273 		log_warn("imsg compose REFS_UPDATED");
274 }
275 
276 static const struct got_error *
277 send_ref_update_ng(struct gotd_session_client *client,
278     struct gotd_imsg_ref_update *iref, const char *refname,
279     const char *reason)
280 {
281 	const struct got_error *ng_err;
282 	struct gotd_imsg_ref_update_ng ing;
283 	struct gotd_imsgev *iev = &client->iev;
284 	struct ibuf *wbuf;
285 	size_t len;
286 
287 	memset(&ing, 0, sizeof(ing));
288 	memcpy(ing.old_id, iref->old_id, SHA1_DIGEST_LENGTH);
289 	memcpy(ing.new_id, iref->new_id, SHA1_DIGEST_LENGTH);
290 	ing.name_len = strlen(refname);
291 
292 	ng_err = got_error_fmt(GOT_ERR_REF_BUSY, "%s", reason);
293 	ing.reason_len = strlen(ng_err->msg);
294 
295 	len = sizeof(ing) + ing.name_len + ing.reason_len;
296 	wbuf = imsg_create(&iev->ibuf, GOTD_IMSG_REF_UPDATE_NG,
297 	    PROC_SESSION_WRITE, gotd_session.pid, len);
298 	if (wbuf == NULL)
299 		return got_error_from_errno("imsg_create REF_UPDATE_NG");
300 
301 	if (imsg_add(wbuf, &ing, sizeof(ing)) == -1)
302 		return got_error_from_errno("imsg_add REF_UPDATE_NG");
303 	if (imsg_add(wbuf, refname, ing.name_len) == -1)
304 		return got_error_from_errno("imsg_add REF_UPDATE_NG");
305 	if (imsg_add(wbuf, ng_err->msg, ing.reason_len) == -1)
306 		return got_error_from_errno("imsg_add REF_UPDATE_NG");
307 
308 	imsg_close(&iev->ibuf, wbuf);
309 	gotd_imsg_event_add(iev);
310 	return NULL;
311 }
312 
313 static const struct got_error *
314 install_pack(struct gotd_session_client *client, const char *repo_path,
315     struct imsg *imsg)
316 {
317 	const struct got_error *err = NULL;
318 	struct gotd_imsg_packfile_install inst;
319 	char hex[SHA1_DIGEST_STRING_LENGTH];
320 	size_t datalen;
321 	char *packfile_path = NULL, *packidx_path = NULL;
322 
323 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
324 	if (datalen != sizeof(inst))
325 		return got_error(GOT_ERR_PRIVSEP_LEN);
326 	memcpy(&inst, imsg->data, sizeof(inst));
327 
328 	if (client->packfile_path == NULL)
329 		return got_error_msg(GOT_ERR_BAD_REQUEST,
330 		    "client has no pack file");
331 	if (client->packidx_path == NULL)
332 		return got_error_msg(GOT_ERR_BAD_REQUEST,
333 		    "client has no pack file index");
334 
335 	if (got_sha1_digest_to_str(inst.pack_sha1, hex, sizeof(hex)) == NULL)
336 		return got_error_msg(GOT_ERR_NO_SPACE,
337 		    "could not convert pack file SHA1 to hex");
338 
339 	if (asprintf(&packfile_path, "/%s/%s/pack-%s.pack",
340 	    repo_path, GOT_OBJECTS_PACK_DIR, hex) == -1) {
341 		err = got_error_from_errno("asprintf");
342 		goto done;
343 	}
344 
345 	if (asprintf(&packidx_path, "/%s/%s/pack-%s.idx",
346 	    repo_path, GOT_OBJECTS_PACK_DIR, hex) == -1) {
347 		err = got_error_from_errno("asprintf");
348 		goto done;
349 	}
350 
351 	if (rename(client->packfile_path, packfile_path) == -1) {
352 		err = got_error_from_errno3("rename", client->packfile_path,
353 		    packfile_path);
354 		goto done;
355 	}
356 
357 	free(client->packfile_path);
358 	client->packfile_path = NULL;
359 
360 	if (rename(client->packidx_path, packidx_path) == -1) {
361 		err = got_error_from_errno3("rename", client->packidx_path,
362 		    packidx_path);
363 		goto done;
364 	}
365 
366 	/* Ensure we re-read the pack index list upon next access. */
367 	gotd_session.repo->pack_path_mtime.tv_sec = 0;
368 	gotd_session.repo->pack_path_mtime.tv_nsec = 0;
369 
370 	free(client->packidx_path);
371 	client->packidx_path = NULL;
372 done:
373 	free(packfile_path);
374 	free(packidx_path);
375 	return err;
376 }
377 
378 static const struct got_error *
379 begin_ref_updates(struct gotd_session_client *client, struct imsg *imsg)
380 {
381 	struct gotd_imsg_ref_updates_start istart;
382 	size_t datalen;
383 
384 	if (client->nref_updates != -1)
385 		return got_error(GOT_ERR_PRIVSEP_MSG);
386 
387 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
388 	if (datalen != sizeof(istart))
389 		return got_error(GOT_ERR_PRIVSEP_LEN);
390 	memcpy(&istart, imsg->data, sizeof(istart));
391 
392 	if (istart.nref_updates <= 0)
393 		return got_error(GOT_ERR_PRIVSEP_MSG);
394 
395 	client->nref_updates = istart.nref_updates;
396 	return NULL;
397 }
398 
399 static const struct got_error *
400 validate_namespace(const char *namespace)
401 {
402 	size_t len = strlen(namespace);
403 
404 	if (len < 5 || strncmp("refs/", namespace, 5) != 0 ||
405 	    namespace[len - 1] != '/') {
406 		return got_error_fmt(GOT_ERR_BAD_REF_NAME,
407 		    "reference namespace '%s'", namespace);
408 	}
409 
410 	return NULL;
411 }
412 
413 static const struct got_error *
414 queue_notification(struct got_object_id *old_id, struct got_object_id *new_id,
415     struct got_repository *repo, struct got_reference *ref)
416 {
417 	const struct got_error *err = NULL;
418 	struct gotd_repo *repo_cfg = gotd_session.repo_cfg;
419 	struct gotd_imsgev *iev = &gotd_session.repo_child_iev;
420 	struct got_pathlist_entry *pe;
421 	struct gotd_session_notif *notif;
422 
423 	if (iev->ibuf.fd == -1 ||
424 	    STAILQ_EMPTY(&repo_cfg->notification_targets))
425 		return NULL; /* notifications unused */
426 
427 	TAILQ_FOREACH(pe, &repo_cfg->notification_refs, entry) {
428 		const char *refname = pe->path;
429 		if (strcmp(got_ref_get_name(ref), refname) == 0)
430 			break;
431 	}
432 	if (pe == NULL) {
433 		TAILQ_FOREACH(pe, &repo_cfg->notification_ref_namespaces,
434 		    entry) {
435 			const char *namespace = pe->path;
436 
437 			err = validate_namespace(namespace);
438 			if (err)
439 				return err;
440 			if (strncmp(namespace, got_ref_get_name(ref),
441 			    strlen(namespace)) == 0)
442 				break;
443 		}
444 	}
445 
446 	/*
447 	 * If a branch or a reference namespace was specified in the
448 	 * configuration file then only send notifications if a match
449 	 * was found.
450 	 */
451 	if (pe == NULL && (!TAILQ_EMPTY(&repo_cfg->notification_refs) ||
452 	    !TAILQ_EMPTY(&repo_cfg->notification_ref_namespaces)))
453 		return NULL;
454 
455 	notif = calloc(1, sizeof(*notif));
456 	if (notif == NULL)
457 		return got_error_from_errno("calloc");
458 
459 	notif->fd = -1;
460 
461 	if (old_id == NULL)
462 		notif->action = GOTD_NOTIF_ACTION_CREATED;
463 	else if (new_id == NULL)
464 		notif->action = GOTD_NOTIF_ACTION_REMOVED;
465 	else
466 		notif->action = GOTD_NOTIF_ACTION_CHANGED;
467 
468 	if (old_id != NULL)
469 		memcpy(&notif->old_id, old_id, sizeof(notif->old_id));
470 	if (new_id != NULL)
471 		memcpy(&notif->new_id, new_id, sizeof(notif->new_id));
472 
473 	notif->refname = strdup(got_ref_get_name(ref));
474 	if (notif->refname == NULL) {
475 		err = got_error_from_errno("strdup");
476 		goto done;
477 	}
478 
479 	STAILQ_INSERT_TAIL(&notifications, notif, entry);
480 done:
481 	if (err && notif) {
482 		free(notif->refname);
483 		free(notif);
484 	}
485 	return err;
486 }
487 
488 /* Forward notification content to the NOTIFY process. */
489 static const struct got_error *
490 forward_notification(struct gotd_session_client *client, struct imsg *imsg)
491 {
492 	const struct got_error *err = NULL;
493 	struct gotd_imsgev *iev = &gotd_session.notifier_iev;
494 	struct gotd_session_notif *notif;
495 	struct gotd_imsg_notification_content icontent;
496 	char *refname = NULL;
497 	size_t datalen;
498 	struct gotd_imsg_notify inotify;
499 	const char *action;
500 	struct ibuf *wbuf;
501 
502 	memset(&inotify, 0, sizeof(inotify));
503 
504 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
505 	if (datalen < sizeof(icontent))
506 		return got_error(GOT_ERR_PRIVSEP_LEN);
507 	memcpy(&icontent, imsg->data, sizeof(icontent));
508 	if (datalen != sizeof(icontent) + icontent.refname_len)
509 		return got_error(GOT_ERR_PRIVSEP_LEN);
510 	refname = strndup(imsg->data + sizeof(icontent), icontent.refname_len);
511 	if (refname == NULL)
512 		return got_error_from_errno("strndup");
513 
514 	notif = STAILQ_FIRST(&notifications);
515 	if (notif == NULL)
516 		return got_error(GOT_ERR_PRIVSEP_MSG);
517 
518 	STAILQ_REMOVE(&notifications, notif, gotd_session_notif, entry);
519 
520 	if (notif->action != icontent.action || notif->fd == -1 ||
521 	    strcmp(notif->refname, refname) != 0) {
522 		err = got_error(GOT_ERR_PRIVSEP_MSG);
523 		goto done;
524 	}
525 	if (notif->action == GOTD_NOTIF_ACTION_CREATED) {
526 		if (memcmp(notif->new_id.sha1, icontent.new_id,
527 		    SHA1_DIGEST_LENGTH) != 0) {
528 			err = got_error_msg(GOT_ERR_PRIVSEP_MSG,
529 			    "received notification content for unknown event");
530 			goto done;
531 		}
532 	} else if (notif->action == GOTD_NOTIF_ACTION_REMOVED) {
533 		if (memcmp(notif->old_id.sha1, icontent.old_id,
534 		    SHA1_DIGEST_LENGTH) != 0) {
535 			err = got_error_msg(GOT_ERR_PRIVSEP_MSG,
536 			    "received notification content for unknown event");
537 			goto done;
538 		}
539 	} else if (memcmp(notif->old_id.sha1, icontent.old_id,
540 	    SHA1_DIGEST_LENGTH) != 0 ||
541 	    memcmp(notif->new_id.sha1, icontent.new_id,
542 	    SHA1_DIGEST_LENGTH) != 0) {
543 		err = got_error_msg(GOT_ERR_PRIVSEP_MSG,
544 		    "received notification content for unknown event");
545 		goto done;
546 	}
547 
548 	switch (notif->action) {
549 	case GOTD_NOTIF_ACTION_CREATED:
550 		action = "created";
551 		break;
552 	case GOTD_NOTIF_ACTION_REMOVED:
553 		action = "removed";
554 		break;
555 	case GOTD_NOTIF_ACTION_CHANGED:
556 		action = "changed";
557 		break;
558 	default:
559 		err = got_error(GOT_ERR_PRIVSEP_MSG);
560 		goto done;
561 	}
562 
563 	strlcpy(inotify.repo_name, gotd_session.repo_cfg->name,
564 	    sizeof(inotify.repo_name));
565 
566 	snprintf(inotify.subject_line, sizeof(inotify.subject_line),
567 	    "%s: %s %s %s", gotd_session.repo_cfg->name,
568 	    client->username, action, notif->refname);
569 
570 	inotify.username_len = strlen(client->username);
571 	wbuf = imsg_create(&iev->ibuf, GOTD_IMSG_NOTIFY,
572 	    PROC_SESSION_WRITE, gotd_session.pid,
573 	    sizeof(inotify) + inotify.username_len);
574 	if (wbuf == NULL) {
575 		err = got_error_from_errno("imsg_create NOTIFY");
576 		goto done;
577 	}
578 	if (imsg_add(wbuf, &inotify, sizeof(inotify)) == -1) {
579 		err = got_error_from_errno("imsg_add NOTIFY");
580 		goto done;
581 	}
582 	if (imsg_add(wbuf, client->username, inotify.username_len) == -1) {
583 		err = got_error_from_errno("imsg_add NOTIFY");
584 		goto done;
585 	}
586 
587 	ibuf_fd_set(wbuf, notif->fd);
588 	notif->fd = -1;
589 
590 	imsg_close(&iev->ibuf, wbuf);
591 	gotd_imsg_event_add(iev);
592 done:
593 	if (notif->fd != -1)
594 		close(notif->fd);
595 	free(notif);
596 	free(refname);
597 	return err;
598 }
599 
600 /* Request notification content from REPO_WRITE process. */
601 static const struct got_error *
602 request_notification(struct gotd_session_notif *notif)
603 {
604 	const struct got_error *err = NULL;
605 	struct gotd_imsgev *iev = &gotd_session.repo_child_iev;
606 	struct gotd_imsg_notification_content icontent;
607 	struct ibuf *wbuf;
608 	size_t len;
609 	int fd;
610 
611 	fd = got_opentempfd();
612 	if (fd == -1)
613 		return got_error_from_errno("got_opentemp");
614 
615 	memset(&icontent, 0, sizeof(icontent));
616 
617 	icontent.action = notif->action;
618 	memcpy(&icontent.old_id, &notif->old_id, sizeof(notif->old_id));
619 	memcpy(&icontent.new_id, &notif->new_id, sizeof(notif->new_id));
620 	icontent.refname_len = strlen(notif->refname);
621 
622 	len = sizeof(icontent) + icontent.refname_len;
623 	wbuf = imsg_create(&iev->ibuf, GOTD_IMSG_NOTIFY,
624 	    PROC_SESSION_WRITE, gotd_session.pid, len);
625 	if (wbuf == NULL) {
626 		err = got_error_from_errno("imsg_create NOTIFY");
627 		goto done;
628 	}
629 	if (imsg_add(wbuf, &icontent, sizeof(icontent)) == -1) {
630 		err = got_error_from_errno("imsg_add NOTIFY");
631 		goto done;
632 	}
633 	if (imsg_add(wbuf, notif->refname, icontent.refname_len) == -1) {
634 		err = got_error_from_errno("imsg_add NOTIFY");
635 		goto done;
636 	}
637 
638 	notif->fd = dup(fd);
639 	if (notif->fd == -1) {
640 		err = got_error_from_errno("dup");
641 		goto done;
642 	}
643 
644 	ibuf_fd_set(wbuf, fd);
645 	fd = -1;
646 
647 	imsg_close(&iev->ibuf, wbuf);
648 	gotd_imsg_event_add(iev);
649 done:
650 	if (err && fd != -1)
651 		close(fd);
652 	return err;
653 }
654 
655 static const struct got_error *
656 update_ref(int *shut, struct gotd_session_client *client,
657     const char *repo_path, struct imsg *imsg)
658 {
659 	const struct got_error *err = NULL;
660 	struct got_repository *repo = gotd_session.repo;
661 	struct got_reference *ref = NULL;
662 	struct gotd_imsg_ref_update iref;
663 	struct got_object_id old_id, new_id;
664 	struct gotd_session_notif *notif;
665 	struct got_object_id *id = NULL;
666 	char *refname = NULL;
667 	size_t datalen;
668 	int locked = 0;
669 	char hex1[SHA1_DIGEST_STRING_LENGTH];
670 	char hex2[SHA1_DIGEST_STRING_LENGTH];
671 
672 	log_debug("update-ref from uid %d", client->euid);
673 
674 	if (client->nref_updates <= 0)
675 		return got_error(GOT_ERR_PRIVSEP_MSG);
676 
677 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
678 	if (datalen < sizeof(iref))
679 		return got_error(GOT_ERR_PRIVSEP_LEN);
680 	memcpy(&iref, imsg->data, sizeof(iref));
681 	if (datalen != sizeof(iref) + iref.name_len)
682 		return got_error(GOT_ERR_PRIVSEP_LEN);
683 	refname = strndup(imsg->data + sizeof(iref), iref.name_len);
684 	if (refname == NULL)
685 		return got_error_from_errno("strndup");
686 
687 	log_debug("updating ref %s for uid %d", refname, client->euid);
688 
689 	memcpy(old_id.sha1, iref.old_id, SHA1_DIGEST_LENGTH);
690 	memcpy(new_id.sha1, iref.new_id, SHA1_DIGEST_LENGTH);
691 	err = got_repo_find_object_id(iref.delete_ref ? &old_id : &new_id,
692 	    repo);
693 	if (err)
694 		goto done;
695 
696 	if (iref.ref_is_new) {
697 		err = got_ref_open(&ref, repo, refname, 0);
698 		if (err) {
699 			if (err->code != GOT_ERR_NOT_REF)
700 				goto done;
701 			err = got_ref_alloc(&ref, refname, &new_id);
702 			if (err)
703 				goto done;
704 			err = got_ref_write(ref, repo); /* will lock/unlock */
705 			if (err)
706 				goto done;
707 			err = queue_notification(NULL, &new_id, repo, ref);
708 			if (err)
709 				goto done;
710 		} else {
711 			err = got_ref_resolve(&id, repo, ref);
712 			if (err)
713 				goto done;
714 			got_object_id_hex(&new_id, hex1, sizeof(hex1));
715 			got_object_id_hex(id, hex2, sizeof(hex2));
716 			err = got_error_fmt(GOT_ERR_REF_BUSY,
717 			    "Addition %s: %s failed; %s: %s has been "
718 			    "created by someone else while transaction "
719 			    "was in progress",
720 			    got_ref_get_name(ref), hex1,
721 			    got_ref_get_name(ref), hex2);
722 			goto done;
723 		}
724 	} else if (iref.delete_ref) {
725 		err = got_ref_open(&ref, repo, refname, 1 /* lock */);
726 		if (err)
727 			goto done;
728 		locked = 1;
729 
730 		err = got_ref_resolve(&id, repo, ref);
731 		if (err)
732 			goto done;
733 
734 		if (got_object_id_cmp(id, &old_id) != 0) {
735 			got_object_id_hex(&old_id, hex1, sizeof(hex1));
736 			got_object_id_hex(id, hex2, sizeof(hex2));
737 			err = got_error_fmt(GOT_ERR_REF_BUSY,
738 			    "Deletion %s: %s failed; %s: %s has been "
739 			    "created by someone else while transaction "
740 			    "was in progress",
741 			    got_ref_get_name(ref), hex1,
742 			    got_ref_get_name(ref), hex2);
743 			goto done;
744 		}
745 
746 		err = got_ref_delete(ref, repo);
747 		if (err)
748 			goto done;
749 		err = queue_notification(&old_id, NULL, repo, ref);
750 		if (err)
751 			goto done;
752 		free(id);
753 		id = NULL;
754 	} else {
755 		err = got_ref_open(&ref, repo, refname, 1 /* lock */);
756 		if (err)
757 			goto done;
758 		locked = 1;
759 
760 		err = got_ref_resolve(&id, repo, ref);
761 		if (err)
762 			goto done;
763 
764 		if (got_object_id_cmp(id, &old_id) != 0) {
765 			got_object_id_hex(&old_id, hex1, sizeof(hex1));
766 			got_object_id_hex(id, hex2, sizeof(hex2));
767 			err = got_error_fmt(GOT_ERR_REF_BUSY,
768 			    "Update %s: %s failed; %s: %s has been "
769 			    "created by someone else while transaction "
770 			    "was in progress",
771 			    got_ref_get_name(ref), hex1,
772 			    got_ref_get_name(ref), hex2);
773 			goto done;
774 		}
775 
776 		if (got_object_id_cmp(&new_id, &old_id) != 0) {
777 			err = got_ref_change_ref(ref, &new_id);
778 			if (err)
779 				goto done;
780 			err = got_ref_write(ref, repo);
781 			if (err)
782 				goto done;
783 			err = queue_notification(&old_id, &new_id, repo, ref);
784 			if (err)
785 				goto done;
786 		}
787 
788 		free(id);
789 		id = NULL;
790 	}
791 done:
792 	if (err) {
793 		if (err->code == GOT_ERR_LOCKFILE_TIMEOUT) {
794 			err = got_error_fmt(GOT_ERR_LOCKFILE_TIMEOUT,
795 			    "could not acquire exclusive file lock for %s",
796 			    refname);
797 		}
798 		send_ref_update_ng(client, &iref, refname, err->msg);
799 	} else
800 		send_ref_update_ok(client, &iref, refname);
801 
802 	if (client->nref_updates > 0) {
803 		client->nref_updates--;
804 		if (client->nref_updates == 0) {
805 			send_refs_updated(client);
806 			notif = STAILQ_FIRST(&notifications);
807 			if (notif) {
808 				gotd_session.state = GOTD_STATE_NOTIFY;
809 				err = request_notification(notif);
810 				if (err) {
811 					log_warn("could not send notification: "
812 					    "%s", err->msg);
813 					client->flush_disconnect = 1;
814 				}
815 			} else
816 				client->flush_disconnect = 1;
817 		}
818 
819 	}
820 	if (locked) {
821 		const struct got_error *unlock_err;
822 		unlock_err = got_ref_unlock(ref);
823 		if (unlock_err && err == NULL)
824 			err = unlock_err;
825 	}
826 	if (ref)
827 		got_ref_close(ref);
828 	free(refname);
829 	free(id);
830 	return err;
831 }
832 
833 static const struct got_error *
834 recv_notification_content(struct imsg *imsg)
835 {
836 	struct gotd_imsg_notification_content inotif;
837 	size_t datalen;
838 
839 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
840 	if (datalen < sizeof(inotif))
841 		return got_error(GOT_ERR_PRIVSEP_LEN);
842 	memcpy(&inotif, imsg->data, sizeof(inotif));
843 
844 	return NULL;
845 }
846 
847 static void
848 session_dispatch_repo_child(int fd, short event, void *arg)
849 {
850 	struct gotd_imsgev *iev = arg;
851 	struct imsgbuf *ibuf = &iev->ibuf;
852 	struct gotd_session_client *client = &gotd_session_client;
853 	ssize_t n;
854 	int shut = 0;
855 	struct imsg imsg;
856 
857 	if (event & EV_READ) {
858 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
859 			fatal("imsg_read error");
860 		if (n == 0) {
861 			/* Connection closed. */
862 			shut = 1;
863 			goto done;
864 		}
865 	}
866 
867 	if (event & EV_WRITE) {
868 		n = msgbuf_write(&ibuf->w);
869 		if (n == -1 && errno != EAGAIN)
870 			fatal("msgbuf_write");
871 		if (n == 0) {
872 			/* Connection closed. */
873 			shut = 1;
874 			goto done;
875 		}
876 	}
877 
878 	for (;;) {
879 		const struct got_error *err = NULL;
880 		uint32_t client_id = 0;
881 		int do_disconnect = 0;
882 		int do_ref_updates = 0, do_ref_update = 0;
883 		int do_packfile_install = 0, do_notify = 0;
884 
885 		if ((n = imsg_get(ibuf, &imsg)) == -1)
886 			fatal("%s: imsg_get error", __func__);
887 		if (n == 0)	/* No more messages. */
888 			break;
889 
890 		switch (imsg.hdr.type) {
891 		case GOTD_IMSG_ERROR:
892 			do_disconnect = 1;
893 			err = gotd_imsg_recv_error(&client_id, &imsg);
894 			break;
895 		case GOTD_IMSG_PACKFILE_INSTALL:
896 			err = recv_packfile_install(&imsg);
897 			if (err == NULL)
898 				do_packfile_install = 1;
899 			break;
900 		case GOTD_IMSG_REF_UPDATES_START:
901 			err = recv_ref_updates_start(&imsg);
902 			if (err == NULL)
903 				do_ref_updates = 1;
904 			break;
905 		case GOTD_IMSG_REF_UPDATE:
906 			err = recv_ref_update(&imsg);
907 			if (err == NULL)
908 				do_ref_update = 1;
909 			break;
910 		case GOTD_IMSG_NOTIFY:
911 			err = recv_notification_content(&imsg);
912 			if (err == NULL)
913 				do_notify = 1;
914 			break;
915 		default:
916 			log_debug("unexpected imsg %d", imsg.hdr.type);
917 			break;
918 		}
919 
920 		if (do_disconnect || err) {
921 			if (err)
922 				disconnect_on_error(client, err);
923 			else
924 				disconnect(client);
925 		} else {
926 			struct gotd_session_notif *notif;
927 
928 			if (do_packfile_install)
929 				err = install_pack(client,
930 				    gotd_session.repo->path, &imsg);
931 			else if (do_ref_updates)
932 				err = begin_ref_updates(client, &imsg);
933 			else if (do_ref_update)
934 				err = update_ref(&shut, client,
935 				    gotd_session.repo->path, &imsg);
936 			else if (do_notify)
937 				err = forward_notification(client, &imsg);
938 			if (err)
939 				log_warnx("uid %d: %s", client->euid, err->msg);
940 
941 			notif = STAILQ_FIRST(&notifications);
942 			if (notif && do_notify) {
943 				/* Request content for next notification. */
944 				err = request_notification(notif);
945 				if (err) {
946 					log_warn("could not send notification: "
947 					    "%s", err->msg);
948 					shut = 1;
949 				}
950 			}
951 		}
952 		imsg_free(&imsg);
953 	}
954 done:
955 	if (!shut) {
956 		gotd_imsg_event_add(iev);
957 	} else {
958 		/* This pipe is dead. Remove its event handler */
959 		event_del(&iev->ev);
960 		event_loopexit(NULL);
961 	}
962 }
963 
964 static const struct got_error *
965 recv_capabilities(struct gotd_session_client *client, struct imsg *imsg)
966 {
967 	struct gotd_imsg_capabilities icapas;
968 	size_t datalen;
969 
970 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
971 	if (datalen != sizeof(icapas))
972 		return got_error(GOT_ERR_PRIVSEP_LEN);
973 	memcpy(&icapas, imsg->data, sizeof(icapas));
974 
975 	client->ncapa_alloc = icapas.ncapabilities;
976 	client->capabilities = calloc(client->ncapa_alloc,
977 	    sizeof(*client->capabilities));
978 	if (client->capabilities == NULL) {
979 		client->ncapa_alloc = 0;
980 		return got_error_from_errno("calloc");
981 	}
982 
983 	log_debug("expecting %zu capabilities from uid %d",
984 	    client->ncapa_alloc, client->euid);
985 	return NULL;
986 }
987 
988 static const struct got_error *
989 recv_capability(struct gotd_session_client *client, struct imsg *imsg)
990 {
991 	struct gotd_imsg_capability icapa;
992 	struct gotd_client_capability *capa;
993 	size_t datalen;
994 	char *key, *value = NULL;
995 
996 	if (client->capabilities == NULL ||
997 	    client->ncapabilities >= client->ncapa_alloc) {
998 		return got_error_msg(GOT_ERR_BAD_REQUEST,
999 		    "unexpected capability received");
1000 	}
1001 
1002 	memset(&icapa, 0, sizeof(icapa));
1003 
1004 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
1005 	if (datalen < sizeof(icapa))
1006 		return got_error(GOT_ERR_PRIVSEP_LEN);
1007 	memcpy(&icapa, imsg->data, sizeof(icapa));
1008 
1009 	if (datalen != sizeof(icapa) + icapa.key_len + icapa.value_len)
1010 		return got_error(GOT_ERR_PRIVSEP_LEN);
1011 
1012 	key = strndup(imsg->data + sizeof(icapa), icapa.key_len);
1013 	if (key == NULL)
1014 		return got_error_from_errno("strndup");
1015 	if (icapa.value_len > 0) {
1016 		value = strndup(imsg->data + sizeof(icapa) + icapa.key_len,
1017 		    icapa.value_len);
1018 		if (value == NULL) {
1019 			free(key);
1020 			return got_error_from_errno("strndup");
1021 		}
1022 	}
1023 
1024 	capa = &client->capabilities[client->ncapabilities++];
1025 	capa->key = key;
1026 	capa->value = value;
1027 
1028 	if (value)
1029 		log_debug("uid %d: capability %s=%s", client->euid, key, value);
1030 	else
1031 		log_debug("uid %d: capability %s", client->euid, key);
1032 
1033 	return NULL;
1034 }
1035 
1036 static const struct got_error *
1037 forward_ref_update(struct gotd_session_client *client, struct imsg *imsg)
1038 {
1039 	const struct got_error *err = NULL;
1040 	struct gotd_imsg_ref_update ireq;
1041 	struct gotd_imsg_ref_update *iref = NULL;
1042 	size_t datalen;
1043 
1044 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
1045 	if (datalen < sizeof(ireq))
1046 		return got_error(GOT_ERR_PRIVSEP_LEN);
1047 	memcpy(&ireq, imsg->data, sizeof(ireq));
1048 	if (datalen != sizeof(ireq) + ireq.name_len)
1049 		return got_error(GOT_ERR_PRIVSEP_LEN);
1050 
1051 	iref = malloc(datalen);
1052 	if (iref == NULL)
1053 		return got_error_from_errno("malloc");
1054 	memcpy(iref, imsg->data, datalen);
1055 
1056 	if (gotd_imsg_compose_event(&gotd_session.repo_child_iev,
1057 	    GOTD_IMSG_REF_UPDATE, PROC_SESSION_WRITE, -1,
1058 	    iref, datalen) == -1)
1059 		err = got_error_from_errno("imsg compose REF_UPDATE");
1060 	free(iref);
1061 	return err;
1062 }
1063 
1064 static int
1065 client_has_capability(struct gotd_session_client *client, const char *capastr)
1066 {
1067 	struct gotd_client_capability *capa;
1068 	size_t i;
1069 
1070 	if (client->ncapabilities == 0)
1071 		return 0;
1072 
1073 	for (i = 0; i < client->ncapabilities; i++) {
1074 		capa = &client->capabilities[i];
1075 		if (strcmp(capa->key, capastr) == 0)
1076 			return 1;
1077 	}
1078 
1079 	return 0;
1080 }
1081 
1082 static const struct got_error *
1083 recv_packfile(struct gotd_session_client *client)
1084 {
1085 	const struct got_error *err = NULL;
1086 	struct gotd_imsg_recv_packfile ipack;
1087 	char *basepath = NULL, *pack_path = NULL, *idx_path = NULL;
1088 	int packfd = -1, idxfd = -1;
1089 	int pipe[2] = { -1, -1 };
1090 
1091 	if (client->packfile_path) {
1092 		return got_error_fmt(GOT_ERR_PRIVSEP_MSG,
1093 		    "uid %d already has a pack file", client->euid);
1094 	}
1095 
1096 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, pipe) == -1)
1097 		return got_error_from_errno("socketpair");
1098 
1099 	/* Send pack pipe end 0 to repo child process. */
1100 	if (gotd_imsg_compose_event(&gotd_session.repo_child_iev,
1101 	    GOTD_IMSG_PACKFILE_PIPE, PROC_SESSION_WRITE, pipe[0],
1102 	        NULL, 0) == -1) {
1103 		err = got_error_from_errno("imsg compose PACKFILE_PIPE");
1104 		pipe[0] = -1;
1105 		goto done;
1106 	}
1107 	pipe[0] = -1;
1108 
1109 	/* Send pack pipe end 1 to gotsh(1) (expects just an fd, no data). */
1110 	if (gotd_imsg_compose_event(&client->iev,
1111 	    GOTD_IMSG_PACKFILE_PIPE, PROC_SESSION_WRITE, pipe[1],
1112 	    NULL, 0) == -1)
1113 		err = got_error_from_errno("imsg compose PACKFILE_PIPE");
1114 	pipe[1] = -1;
1115 
1116 	if (asprintf(&basepath, "%s/%s/receiving-from-uid-%d.pack",
1117 	    got_repo_get_path(gotd_session.repo), GOT_OBJECTS_PACK_DIR,
1118 	    client->euid) == -1) {
1119 		err = got_error_from_errno("asprintf");
1120 		goto done;
1121 	}
1122 
1123 	err = got_opentemp_named_fd(&pack_path, &packfd, basepath, "");
1124 	if (err)
1125 		goto done;
1126 	if (fchmod(packfd, GOT_DEFAULT_PACK_MODE) == -1) {
1127 		err = got_error_from_errno2("fchmod", pack_path);
1128 		goto done;
1129 	}
1130 
1131 	free(basepath);
1132 	if (asprintf(&basepath, "%s/%s/receiving-from-uid-%d.idx",
1133 	    got_repo_get_path(gotd_session.repo), GOT_OBJECTS_PACK_DIR,
1134 	    client->euid) == -1) {
1135 		err = got_error_from_errno("asprintf");
1136 		basepath = NULL;
1137 		goto done;
1138 	}
1139 	err = got_opentemp_named_fd(&idx_path, &idxfd, basepath, "");
1140 	if (err)
1141 		goto done;
1142 	if (fchmod(idxfd, GOT_DEFAULT_PACK_MODE) == -1) {
1143 		err = got_error_from_errno2("fchmod", idx_path);
1144 		goto done;
1145 	}
1146 
1147 	if (gotd_imsg_compose_event(&gotd_session.repo_child_iev,
1148 	    GOTD_IMSG_PACKIDX_FILE, PROC_SESSION_WRITE,
1149 	    idxfd, NULL, 0) == -1) {
1150 		err = got_error_from_errno("imsg compose PACKIDX_FILE");
1151 		idxfd = -1;
1152 		goto done;
1153 	}
1154 	idxfd = -1;
1155 
1156 	memset(&ipack, 0, sizeof(ipack));
1157 	if (client_has_capability(client, GOT_CAPA_REPORT_STATUS))
1158 		ipack.report_status = 1;
1159 
1160 	if (gotd_imsg_compose_event(&gotd_session.repo_child_iev,
1161 	    GOTD_IMSG_RECV_PACKFILE, PROC_SESSION_WRITE, packfd,
1162 	    &ipack, sizeof(ipack)) == -1) {
1163 		err = got_error_from_errno("imsg compose RECV_PACKFILE");
1164 		packfd = -1;
1165 		goto done;
1166 	}
1167 	packfd = -1;
1168 
1169 done:
1170 	free(basepath);
1171 	if (pipe[0] != -1 && close(pipe[0]) == -1 && err == NULL)
1172 		err = got_error_from_errno("close");
1173 	if (pipe[1] != -1 && close(pipe[1]) == -1 && err == NULL)
1174 		err = got_error_from_errno("close");
1175 	if (packfd != -1 && close(packfd) == -1 && err == NULL)
1176 		err = got_error_from_errno("close");
1177 	if (idxfd != -1 && close(idxfd) == -1 && err == NULL)
1178 		err = got_error_from_errno("close");
1179 	if (err) {
1180 		free(pack_path);
1181 		free(idx_path);
1182 	} else {
1183 		client->packfile_path = pack_path;
1184 		client->packidx_path = idx_path;
1185 	}
1186 	return err;
1187 }
1188 
1189 static void
1190 session_dispatch_client(int fd, short events, void *arg)
1191 {
1192 	struct gotd_imsgev *iev = arg;
1193 	struct imsgbuf *ibuf = &iev->ibuf;
1194 	struct gotd_session_client *client = &gotd_session_client;
1195 	const struct got_error *err = NULL;
1196 	struct imsg imsg;
1197 	ssize_t n;
1198 
1199 	if (events & EV_WRITE) {
1200 		while (ibuf->w.queued) {
1201 			n = msgbuf_write(&ibuf->w);
1202 			if (n == -1 && errno == EPIPE) {
1203 				/*
1204 				 * The client has closed its socket.
1205 				 * This can happen when Git clients are
1206 				 * done sending pack file data.
1207 				 */
1208 				msgbuf_clear(&ibuf->w);
1209 				continue;
1210 			} else if (n == -1 && errno != EAGAIN) {
1211 				err = got_error_from_errno("imsg_flush");
1212 				disconnect_on_error(client, err);
1213 				return;
1214 			}
1215 			if (n == 0) {
1216 				/* Connection closed. */
1217 				err = got_error(GOT_ERR_EOF);
1218 				disconnect_on_error(client, err);
1219 				return;
1220 			}
1221 		}
1222 
1223 		if (client->flush_disconnect) {
1224 			disconnect(client);
1225 			return;
1226 		}
1227 	}
1228 
1229 	if ((events & EV_READ) == 0)
1230 		return;
1231 
1232 	memset(&imsg, 0, sizeof(imsg));
1233 
1234 	while (err == NULL) {
1235 		err = gotd_imsg_recv(&imsg, ibuf, 0);
1236 		if (err) {
1237 			if (err->code == GOT_ERR_PRIVSEP_READ)
1238 				err = NULL;
1239 			else if (err->code == GOT_ERR_EOF &&
1240 			    gotd_session.state ==
1241 			    GOTD_STATE_EXPECT_CAPABILITIES) {
1242 				/*
1243 				 * The client has closed its socket before
1244 				 * sending its capability announcement.
1245 				 * This can happen when Git clients have
1246 				 * no ref-updates to send.
1247 				 */
1248 				disconnect_on_error(client, err);
1249 				return;
1250 			}
1251 			break;
1252 		}
1253 
1254 		evtimer_del(&client->tmo);
1255 
1256 		switch (imsg.hdr.type) {
1257 		case GOTD_IMSG_CAPABILITIES:
1258 			if (gotd_session.state !=
1259 			    GOTD_STATE_EXPECT_CAPABILITIES) {
1260 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1261 				    "unexpected capabilities received");
1262 				break;
1263 			}
1264 			log_debug("receiving capabilities from uid %d",
1265 			    client->euid);
1266 			err = recv_capabilities(client, &imsg);
1267 			break;
1268 		case GOTD_IMSG_CAPABILITY:
1269 			if (gotd_session.state != GOTD_STATE_EXPECT_CAPABILITIES) {
1270 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1271 				    "unexpected capability received");
1272 				break;
1273 			}
1274 			err = recv_capability(client, &imsg);
1275 			if (err || client->ncapabilities < client->ncapa_alloc)
1276 				break;
1277 			gotd_session.state = GOTD_STATE_EXPECT_REF_UPDATE;
1278 			client->accept_flush_pkt = 1;
1279 			log_debug("uid %d: expecting ref-update-lines",
1280 			    client->euid);
1281 			break;
1282 		case GOTD_IMSG_REF_UPDATE:
1283 			if (gotd_session.state != GOTD_STATE_EXPECT_REF_UPDATE &&
1284 			    gotd_session.state !=
1285 			    GOTD_STATE_EXPECT_MORE_REF_UPDATES) {
1286 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1287 				    "unexpected ref-update-line received");
1288 				break;
1289 			}
1290 			log_debug("received ref-update-line from uid %d",
1291 			    client->euid);
1292 			err = forward_ref_update(client, &imsg);
1293 			if (err)
1294 				break;
1295 			gotd_session.state = GOTD_STATE_EXPECT_MORE_REF_UPDATES;
1296 			client->accept_flush_pkt = 1;
1297 			break;
1298 		case GOTD_IMSG_FLUSH:
1299 			if (gotd_session.state !=
1300 			    GOTD_STATE_EXPECT_MORE_REF_UPDATES) {
1301 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1302 				    "unexpected flush-pkt received");
1303 				break;
1304 			}
1305 			if (!client->accept_flush_pkt) {
1306 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1307 				    "unexpected flush-pkt received");
1308 				break;
1309 			}
1310 
1311 			/*
1312 			 * Accept just one flush packet at a time.
1313 			 * Future client state transitions will set this flag
1314 			 * again if another flush packet is expected.
1315 			 */
1316 			client->accept_flush_pkt = 0;
1317 
1318 			log_debug("received flush-pkt from uid %d",
1319 			    client->euid);
1320 			if (gotd_session.state ==
1321 			    GOTD_STATE_EXPECT_MORE_REF_UPDATES) {
1322 				gotd_session.state = GOTD_STATE_EXPECT_PACKFILE;
1323 				log_debug("uid %d: expecting packfile",
1324 				    client->euid);
1325 				err = recv_packfile(client);
1326 			} else {
1327 				/* should not happen, see above */
1328 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1329 				    "unexpected client state");
1330 				break;
1331 			}
1332 			break;
1333 		default:
1334 			log_debug("unexpected imsg %d", imsg.hdr.type);
1335 			err = got_error(GOT_ERR_PRIVSEP_MSG);
1336 			break;
1337 		}
1338 
1339 		imsg_free(&imsg);
1340 	}
1341 
1342 	if (err) {
1343 		if (err->code != GOT_ERR_EOF ||
1344 		    gotd_session.state != GOTD_STATE_EXPECT_PACKFILE)
1345 			disconnect_on_error(client, err);
1346 	} else {
1347 		gotd_imsg_event_add(iev);
1348 		evtimer_add(&client->tmo, &gotd_session.request_timeout);
1349 	}
1350 }
1351 
1352 static const struct got_error *
1353 list_refs_request(void)
1354 {
1355 	static const struct got_error *err;
1356 	struct gotd_session_client *client = &gotd_session_client;
1357 	struct gotd_imsgev *iev = &gotd_session.repo_child_iev;
1358 	int fd;
1359 
1360 	if (gotd_session.state != GOTD_STATE_EXPECT_LIST_REFS)
1361 		return got_error(GOT_ERR_PRIVSEP_MSG);
1362 
1363 	fd = dup(client->fd);
1364 	if (fd == -1)
1365 		return got_error_from_errno("dup");
1366 
1367 	if (gotd_imsg_compose_event(iev, GOTD_IMSG_LIST_REFS_INTERNAL,
1368 	    PROC_SESSION_WRITE, fd, NULL, 0) == -1) {
1369 		err = got_error_from_errno("imsg compose LIST_REFS_INTERNAL");
1370 		close(fd);
1371 		return err;
1372 	}
1373 
1374 	gotd_session.state = GOTD_STATE_EXPECT_CAPABILITIES;
1375 	log_debug("uid %d: expecting capabilities", client->euid);
1376 	return NULL;
1377 }
1378 
1379 static const struct got_error *
1380 recv_connect(struct imsg *imsg)
1381 {
1382 	struct gotd_session_client *client = &gotd_session_client;
1383 	struct gotd_imsg_connect iconnect;
1384 	size_t datalen;
1385 
1386 	if (gotd_session.state != GOTD_STATE_EXPECT_LIST_REFS)
1387 		return got_error(GOT_ERR_PRIVSEP_MSG);
1388 
1389 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
1390 	if (datalen < sizeof(iconnect))
1391 		return got_error(GOT_ERR_PRIVSEP_LEN);
1392 	memcpy(&iconnect, imsg->data, sizeof(iconnect));
1393 	if (iconnect.username_len == 0 ||
1394 	    datalen != sizeof(iconnect) + iconnect.username_len)
1395 		return got_error(GOT_ERR_PRIVSEP_LEN);
1396 
1397 	client->euid = iconnect.euid;
1398 	client->egid = iconnect.egid;
1399 	client->fd = imsg_get_fd(imsg);
1400 	if (client->fd == -1)
1401 		return got_error(GOT_ERR_PRIVSEP_NO_FD);
1402 
1403 	client->username = strndup(imsg->data + sizeof(iconnect),
1404 	    iconnect.username_len);
1405 	if (client->username == NULL)
1406 		return got_error_from_errno("strndup");
1407 
1408 	imsg_init(&client->iev.ibuf, client->fd);
1409 	client->iev.handler = session_dispatch_client;
1410 	client->iev.events = EV_READ;
1411 	client->iev.handler_arg = NULL;
1412 	event_set(&client->iev.ev, client->iev.ibuf.fd, EV_READ,
1413 	    session_dispatch_client, &client->iev);
1414 	gotd_imsg_event_add(&client->iev);
1415 	evtimer_set(&client->tmo, gotd_request_timeout, client);
1416 
1417 	return NULL;
1418 }
1419 
1420 static void
1421 session_dispatch_notifier(int fd, short event, void *arg)
1422 {
1423 	const struct got_error *err;
1424 	struct gotd_session_client *client = &gotd_session_client;
1425 	struct gotd_imsgev *iev = arg;
1426 	struct imsgbuf *ibuf = &iev->ibuf;
1427 	ssize_t n;
1428 	int shut = 0;
1429 	struct imsg imsg;
1430 	struct gotd_session_notif *notif;
1431 
1432 	if (event & EV_READ) {
1433 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
1434 			fatal("imsg_read error");
1435 		if (n == 0) {
1436 			/* Connection closed. */
1437 			shut = 1;
1438 			goto done;
1439 		}
1440 	}
1441 
1442 	if (event & EV_WRITE) {
1443 		n = msgbuf_write(&ibuf->w);
1444 		if (n == -1 && errno != EAGAIN)
1445 			fatal("msgbuf_write");
1446 		if (n == 0) {
1447 			/* Connection closed. */
1448 			shut = 1;
1449 			goto done;
1450 		}
1451 	}
1452 
1453 	for (;;) {
1454 		if ((n = imsg_get(ibuf, &imsg)) == -1)
1455 			fatal("%s: imsg_get error", __func__);
1456 		if (n == 0)	/* No more messages. */
1457 			break;
1458 
1459 		switch (imsg.hdr.type) {
1460 		case GOTD_IMSG_NOTIFICATION_SENT:
1461 			if (gotd_session.state != GOTD_STATE_NOTIFY) {
1462 				log_warn("unexpected imsg %d", imsg.hdr.type);
1463 				break;
1464 			}
1465 			notif = STAILQ_FIRST(&notifications);
1466 			if (notif == NULL) {
1467 				disconnect(client);
1468 				break; /* NOTREACHED */
1469 			}
1470 			/* Request content for the next notification. */
1471 			err = request_notification(notif);
1472 			if (err) {
1473 				log_warn("could not send notification: %s",
1474 				    err->msg);
1475 				disconnect(client);
1476 			}
1477 			break;
1478 		default:
1479 			log_debug("unexpected imsg %d", imsg.hdr.type);
1480 			break;
1481 		}
1482 
1483 		imsg_free(&imsg);
1484 	}
1485 done:
1486 	if (!shut) {
1487 		gotd_imsg_event_add(iev);
1488 	} else {
1489 		/* This pipe is dead. Remove its event handler */
1490 		event_del(&iev->ev);
1491 		imsg_clear(&iev->ibuf);
1492 		imsg_init(&iev->ibuf, -1);
1493 	}
1494 }
1495 
1496 static const struct got_error *
1497 recv_notifier(struct imsg *imsg)
1498 {
1499 	struct gotd_imsgev *iev = &gotd_session.notifier_iev;
1500 	struct gotd_session_client *client = &gotd_session_client;
1501 	size_t datalen;
1502 	int fd;
1503 
1504 	if (gotd_session.state != GOTD_STATE_EXPECT_LIST_REFS)
1505 		return got_error(GOT_ERR_PRIVSEP_MSG);
1506 
1507 	/* We should already have received a pipe to the listener. */
1508 	if (client->fd == -1)
1509 		return got_error(GOT_ERR_PRIVSEP_MSG);
1510 
1511 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
1512 	if (datalen != 0)
1513 		return got_error(GOT_ERR_PRIVSEP_LEN);
1514 
1515 	fd = imsg_get_fd(imsg);
1516 	if (fd == -1)
1517 		return NULL; /* notifications unused */
1518 
1519 	imsg_init(&iev->ibuf, fd);
1520 	iev->handler = session_dispatch_notifier;
1521 	iev->events = EV_READ;
1522 	iev->handler_arg = NULL;
1523 	event_set(&iev->ev, iev->ibuf.fd, EV_READ,
1524 	    session_dispatch_notifier, iev);
1525 	gotd_imsg_event_add(iev);
1526 
1527 	return NULL;
1528 }
1529 
1530 static const struct got_error *
1531 recv_repo_child(struct imsg *imsg)
1532 {
1533 	struct gotd_imsg_connect_repo_child ichild;
1534 	struct gotd_session_client *client = &gotd_session_client;
1535 	size_t datalen;
1536 	int fd;
1537 
1538 	if (gotd_session.state != GOTD_STATE_EXPECT_LIST_REFS)
1539 		return got_error(GOT_ERR_PRIVSEP_MSG);
1540 
1541 	/* We should already have received a pipe to the listener. */
1542 	if (client->fd == -1)
1543 		return got_error(GOT_ERR_PRIVSEP_MSG);
1544 
1545 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
1546 	if (datalen != sizeof(ichild))
1547 		return got_error(GOT_ERR_PRIVSEP_LEN);
1548 
1549 	memcpy(&ichild, imsg->data, sizeof(ichild));
1550 
1551 	if (ichild.proc_id != PROC_REPO_WRITE)
1552 		return got_error_msg(GOT_ERR_PRIVSEP_MSG,
1553 		    "bad child process type");
1554 
1555 	fd = imsg_get_fd(imsg);
1556 	if (fd == -1)
1557 		return got_error(GOT_ERR_PRIVSEP_NO_FD);
1558 
1559 	imsg_init(&gotd_session.repo_child_iev.ibuf, fd);
1560 	gotd_session.repo_child_iev.handler = session_dispatch_repo_child;
1561 	gotd_session.repo_child_iev.events = EV_READ;
1562 	gotd_session.repo_child_iev.handler_arg = NULL;
1563 	event_set(&gotd_session.repo_child_iev.ev,
1564 	    gotd_session.repo_child_iev.ibuf.fd, EV_READ,
1565 	    session_dispatch_repo_child, &gotd_session.repo_child_iev);
1566 	gotd_imsg_event_add(&gotd_session.repo_child_iev);
1567 
1568 	/* The "recvfd" pledge promise is no longer needed. */
1569 	if (pledge("stdio rpath wpath cpath sendfd fattr flock", NULL) == -1)
1570 		fatal("pledge");
1571 
1572 	return NULL;
1573 }
1574 
1575 static void
1576 session_dispatch(int fd, short event, void *arg)
1577 {
1578 	struct gotd_imsgev *iev = arg;
1579 	struct imsgbuf *ibuf = &iev->ibuf;
1580 	struct gotd_session_client *client = &gotd_session_client;
1581 	ssize_t n;
1582 	int shut = 0;
1583 	struct imsg imsg;
1584 
1585 	if (event & EV_READ) {
1586 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
1587 			fatal("imsg_read error");
1588 		if (n == 0) {
1589 			/* Connection closed. */
1590 			shut = 1;
1591 			goto done;
1592 		}
1593 	}
1594 
1595 	if (event & EV_WRITE) {
1596 		n = msgbuf_write(&ibuf->w);
1597 		if (n == -1 && errno != EAGAIN)
1598 			fatal("msgbuf_write");
1599 		if (n == 0) {
1600 			/* Connection closed. */
1601 			shut = 1;
1602 			goto done;
1603 		}
1604 	}
1605 
1606 	for (;;) {
1607 		const struct got_error *err = NULL;
1608 		uint32_t client_id = 0;
1609 		int do_disconnect = 0, do_list_refs = 0;
1610 
1611 		if ((n = imsg_get(ibuf, &imsg)) == -1)
1612 			fatal("%s: imsg_get error", __func__);
1613 		if (n == 0)	/* No more messages. */
1614 			break;
1615 
1616 		switch (imsg.hdr.type) {
1617 		case GOTD_IMSG_ERROR:
1618 			do_disconnect = 1;
1619 			err = gotd_imsg_recv_error(&client_id, &imsg);
1620 			break;
1621 		case GOTD_IMSG_CONNECT:
1622 			err = recv_connect(&imsg);
1623 			break;
1624 		case GOTD_IMSG_DISCONNECT:
1625 			do_disconnect = 1;
1626 			break;
1627 		case GOTD_IMSG_CONNECT_NOTIFIER:
1628 			err = recv_notifier(&imsg);
1629 			break;
1630 		case GOTD_IMSG_CONNECT_REPO_CHILD:
1631 			err = recv_repo_child(&imsg);
1632 			if (err)
1633 				break;
1634 			do_list_refs = 1;
1635 			break;
1636 		default:
1637 			log_debug("unexpected imsg %d", imsg.hdr.type);
1638 			break;
1639 		}
1640 		imsg_free(&imsg);
1641 
1642 		if (do_disconnect) {
1643 			if (err)
1644 				disconnect_on_error(client, err);
1645 			else
1646 				disconnect(client);
1647 		} else if (do_list_refs)
1648 			err = list_refs_request();
1649 
1650 		if (err)
1651 			log_warnx("uid %d: %s", client->euid, err->msg);
1652 	}
1653 done:
1654 	if (!shut) {
1655 		gotd_imsg_event_add(iev);
1656 	} else {
1657 		/* This pipe is dead. Remove its event handler */
1658 		event_del(&iev->ev);
1659 		event_loopexit(NULL);
1660 	}
1661 }
1662 
1663 void
1664 session_write_main(const char *title, const char *repo_path,
1665     int *pack_fds, int *temp_fds, struct timeval *request_timeout,
1666     struct gotd_repo *repo_cfg)
1667 {
1668 	const struct got_error *err = NULL;
1669 	struct event evsigint, evsigterm, evsighup, evsigusr1;
1670 
1671 	STAILQ_INIT(&notifications);
1672 
1673 	gotd_session.title = title;
1674 	gotd_session.pid = getpid();
1675 	gotd_session.pack_fds = pack_fds;
1676 	gotd_session.temp_fds = temp_fds;
1677 	memcpy(&gotd_session.request_timeout, request_timeout,
1678 	    sizeof(gotd_session.request_timeout));
1679 	gotd_session.repo_cfg = repo_cfg;
1680 
1681 	imsg_init(&gotd_session.notifier_iev.ibuf, -1);
1682 
1683 	err = got_repo_open(&gotd_session.repo, repo_path, NULL, pack_fds);
1684 	if (err)
1685 		goto done;
1686 	if (!got_repo_is_bare(gotd_session.repo)) {
1687 		err = got_error_msg(GOT_ERR_NOT_GIT_REPO,
1688 		    "bare git repository required");
1689 		goto done;
1690 	}
1691 
1692 	got_repo_temp_fds_set(gotd_session.repo, temp_fds);
1693 
1694 	signal_set(&evsigint, SIGINT, session_write_sighdlr, NULL);
1695 	signal_set(&evsigterm, SIGTERM, session_write_sighdlr, NULL);
1696 	signal_set(&evsighup, SIGHUP, session_write_sighdlr, NULL);
1697 	signal_set(&evsigusr1, SIGUSR1, session_write_sighdlr, NULL);
1698 	signal(SIGPIPE, SIG_IGN);
1699 
1700 	signal_add(&evsigint, NULL);
1701 	signal_add(&evsigterm, NULL);
1702 	signal_add(&evsighup, NULL);
1703 	signal_add(&evsigusr1, NULL);
1704 
1705 	gotd_session.state = GOTD_STATE_EXPECT_LIST_REFS;
1706 
1707 	gotd_session_client.fd = -1;
1708 	gotd_session_client.nref_updates = -1;
1709 	gotd_session_client.delta_cache_fd = -1;
1710 	gotd_session_client.accept_flush_pkt = 1;
1711 
1712 	imsg_init(&gotd_session.parent_iev.ibuf, GOTD_FILENO_MSG_PIPE);
1713 	gotd_session.parent_iev.handler = session_dispatch;
1714 	gotd_session.parent_iev.events = EV_READ;
1715 	gotd_session.parent_iev.handler_arg = NULL;
1716 	event_set(&gotd_session.parent_iev.ev, gotd_session.parent_iev.ibuf.fd,
1717 	    EV_READ, session_dispatch, &gotd_session.parent_iev);
1718 	if (gotd_imsg_compose_event(&gotd_session.parent_iev,
1719 	    GOTD_IMSG_CLIENT_SESSION_READY, PROC_SESSION_WRITE,
1720 	    -1, NULL, 0) == -1) {
1721 		err = got_error_from_errno("imsg compose CLIENT_SESSION_READY");
1722 		goto done;
1723 	}
1724 
1725 	event_dispatch();
1726 done:
1727 	if (err)
1728 		log_warnx("%s: %s", title, err->msg);
1729 	session_write_shutdown();
1730 }
1731 
1732 static void
1733 session_write_shutdown(void)
1734 {
1735 	struct gotd_session_notif *notif;
1736 
1737 	log_debug("%s: shutting down", gotd_session.title);
1738 
1739 	while (!STAILQ_EMPTY(&notifications)) {
1740 		notif = STAILQ_FIRST(&notifications);
1741 		STAILQ_REMOVE_HEAD(&notifications, entry);
1742 		if (notif->fd != -1)
1743 			close(notif->fd);
1744 		free(notif->refname);
1745 		free(notif);
1746 	}
1747 
1748 	if (gotd_session.repo)
1749 		got_repo_close(gotd_session.repo);
1750 	got_repo_pack_fds_close(gotd_session.pack_fds);
1751 	got_repo_temp_fds_close(gotd_session.temp_fds);
1752 	free(gotd_session_client.username);
1753 	exit(0);
1754 }