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Date:: Sat Jan 28 08:09:45 2023 UTC
Message:: gotd: implement the delete-refs capability Allow clients to run "got send -d" against gotd. Clients will send a zero-id as new id for a reference and, in the special but more common case of just deleting and not updating, no pack file will be sent. ok and tweaks by stsp@
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1 /*
2  * Copyright (c) 2022 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/uio.h>
20 
21 #include <errno.h>
22 #include <event.h>
23 #include <poll.h>
24 #include <limits.h>
25 #include <sha1.h>
26 #include <stdio.h>
27 #include <stdint.h>
28 #include <stdlib.h>
29 #include <string.h>
30 #include <imsg.h>
31 #include <unistd.h>
32 
33 #include "got_error.h"
34 #include "got_serve.h"
35 #include "got_path.h"
36 #include "got_version.h"
37 #include "got_reference.h"
38 
39 #include "got_lib_pkt.h"
40 #include "got_lib_dial.h"
41 #include "got_lib_gitproto.h"
42 #include "got_lib_sha1.h"
43 #include "got_lib_poll.h"
44 
45 #include "gotd.h"
46 
47 #ifndef nitems
48 #define nitems(_a)	(sizeof((_a)) / sizeof((_a)[0]))
49 #endif
50 
51 static const struct got_capability read_capabilities[] = {
52 	{ GOT_CAPA_AGENT, "got/" GOT_VERSION_STR },
53 	{ GOT_CAPA_OFS_DELTA, NULL },
54 	{ GOT_CAPA_SIDE_BAND_64K, NULL },
55 };
56 
57 static const struct got_capability write_capabilities[] = {
58 	{ GOT_CAPA_AGENT, "got/" GOT_VERSION_STR },
59 	{ GOT_CAPA_OFS_DELTA, NULL },
60 	{ GOT_CAPA_REPORT_STATUS, NULL },
61 	{ GOT_CAPA_NO_THIN, NULL },
62 	{ GOT_CAPA_DELETE_REFS, NULL },
63 };
64 
65 const struct got_error *
66 got_serve_parse_command(char **command, char **repo_path, const char *gitcmd)
67 {
68 	const struct got_error *err = NULL;
69 	size_t len, cmdlen, pathlen;
70 	char *path0 = NULL, *path, *abspath = NULL, *canonpath = NULL;
71 	const char *relpath;
72 
73 	*command = NULL;
74 	*repo_path = NULL;
75 
76 	len = strlen(gitcmd);
77 
78 	if (len >= strlen(GOT_SERVE_CMD_SEND) &&
79 	    strncmp(gitcmd, GOT_SERVE_CMD_SEND,
80 	    strlen(GOT_SERVE_CMD_SEND)) == 0)
81 		cmdlen = strlen(GOT_SERVE_CMD_SEND);
82 	else if (len >= strlen(GOT_SERVE_CMD_FETCH) &&
83 	    strncmp(gitcmd, GOT_SERVE_CMD_FETCH,
84 	    strlen(GOT_SERVE_CMD_FETCH)) == 0)
85 		cmdlen = strlen(GOT_SERVE_CMD_FETCH);
86 	else
87 		return got_error(GOT_ERR_BAD_PACKET);
88 
89 	if (len <= cmdlen + 1 || gitcmd[cmdlen] != ' ')
90 		return got_error(GOT_ERR_BAD_PACKET);
91 
92 	if (memchr(&gitcmd[cmdlen + 1], '\0', len - cmdlen) == NULL)
93 		return got_error(GOT_ERR_BAD_PATH);
94 
95 	/* Forbid linefeeds in paths, like Git does. */
96 	if (memchr(&gitcmd[cmdlen + 1], '\n', len - cmdlen) != NULL)
97 		return got_error(GOT_ERR_BAD_PATH);
98 
99 	path0 = strdup(&gitcmd[cmdlen + 1]);
100 	if (path0 == NULL)
101 		return got_error_from_errno("strdup");
102 	path = path0;
103 	pathlen = strlen(path);
104 
105 	/*
106 	 * Git clients send a shell command.
107 	 * Trim spaces and quotes around the path.
108 	 */
109 	while (path[0] == '\'' || path[0] == '\"' || path[0] == ' ') {
110 		path++;
111 		pathlen--;
112 	}
113 	while (pathlen > 0 &&
114 	    (path[pathlen - 1] == '\'' || path[pathlen - 1] == '\"' ||
115 	    path[pathlen - 1] == ' ')) {
116 		path[pathlen - 1] = '\0';
117 		pathlen--;
118 	}
119 
120 	/* Deny an empty repository path. */
121 	if (path[0] == '\0' || got_path_is_root_dir(path)) {
122 		err = got_error(GOT_ERR_NOT_GIT_REPO);
123 		goto done;
124 	}
125 
126 	if (asprintf(&abspath, "/%s", path) == -1) {
127 		err = got_error_from_errno("asprintf");
128 		goto done;
129 	}
130 	pathlen = strlen(abspath);
131 	canonpath = malloc(pathlen);
132 	if (canonpath == NULL) {
133 		err = got_error_from_errno("malloc");
134 		goto done;
135 	}
136 	err = got_canonpath(abspath, canonpath, pathlen);
137 	if (err)
138 		goto done;
139 
140 	relpath = canonpath;
141 	while (relpath[0] == '/')
142 		relpath++;
143 	*repo_path = strdup(relpath);
144 	if (*repo_path == NULL) {
145 		err = got_error_from_errno("strdup");
146 		goto done;
147 	}
148 	*command = strndup(gitcmd, cmdlen);
149 	if (*command == NULL)
150 		err = got_error_from_errno("strndup");
151 done:
152 	free(path0);
153 	free(abspath);
154 	free(canonpath);
155 	if (err) {
156 		free(*repo_path);
157 		*repo_path = NULL;
158 	}
159 	return err;
160 }
161 
162 static const struct got_error *
163 append_read_capabilities(size_t *capalen, size_t len, const char *symrefstr,
164     uint8_t *buf, size_t bufsize)
165 {
166 	struct got_capability capa[nitems(read_capabilities) + 1];
167 	size_t ncapa;
168 
169 	memcpy(&capa, read_capabilities, sizeof(read_capabilities));
170 	if (symrefstr) {
171 		capa[nitems(read_capabilities)].key = "symref";
172 		capa[nitems(read_capabilities)].value = symrefstr;
173 		ncapa = nitems(capa);
174 	} else
175 		ncapa = nitems(read_capabilities);
176 
177 	return got_gitproto_append_capabilities(capalen, buf, len,
178 	    bufsize, capa, ncapa);
179 }
180 
181 static const struct got_error *
182 send_ref(int outfd, uint8_t *id, const char *refname, int send_capabilities,
183     int client_is_reading, const char *symrefstr, int chattygot)
184 {
185 	const struct got_error *err = NULL;
186 	char hex[SHA1_DIGEST_STRING_LENGTH];
187 	char buf[GOT_PKT_MAX];
188 	size_t len, capalen = 0;
189 
190 	if (got_sha1_digest_to_str(id, hex, sizeof(hex)) == NULL)
191 		return got_error(GOT_ERR_BAD_OBJ_ID);
192 
193 	len = snprintf(buf, sizeof(buf), "%s %s", hex, refname);
194 	if (len >= sizeof(buf))
195 		return got_error(GOT_ERR_NO_SPACE);
196 
197 	if (send_capabilities) {
198 		if (client_is_reading) {
199 			err = append_read_capabilities(&capalen, len,
200 			    symrefstr, buf, sizeof(buf));
201 		} else {
202 			err = got_gitproto_append_capabilities(&capalen,
203 			    buf, len, sizeof(buf), write_capabilities,
204 			    nitems(write_capabilities));
205 		}
206 		if (err)
207 			return err;
208 		len += capalen;
209 	}
210 
211 	if (len + 1 >= sizeof(buf))
212 		return got_error(GOT_ERR_NO_SPACE);
213 	buf[len] = '\n';
214 	len++;
215 	buf[len] = '\0';
216 
217 	return got_pkt_writepkt(outfd, buf, len, chattygot);
218 }
219 
220 static const struct got_error *
221 send_zero_refs(int outfd, int client_is_reading, int chattygot)
222 {
223 	const struct got_error *err = NULL;
224 	char buf[GOT_PKT_MAX];
225 	uint8_t zero[SHA1_DIGEST_LENGTH];
226 	char hex[SHA1_DIGEST_STRING_LENGTH];
227 	size_t len, capalen = 0;
228 
229 	memset(&zero, 0, sizeof(zero));
230 
231 	if (got_sha1_digest_to_str(zero, hex, sizeof(hex)) == NULL)
232 		return got_error(GOT_ERR_BAD_OBJ_ID);
233 
234 	len = snprintf(buf, sizeof(buf), "%s capabilities^{}", hex);
235 	if (len >= sizeof(buf))
236 		return got_error(GOT_ERR_NO_SPACE);
237 
238 	if (client_is_reading) {
239 		err = got_gitproto_append_capabilities(&capalen, buf, len,
240 		    sizeof(buf), read_capabilities, nitems(read_capabilities));
241 		if (err)
242 			return err;
243 	} else {
244 		err = got_gitproto_append_capabilities(&capalen, buf, len,
245 		    sizeof(buf), write_capabilities,
246 		    nitems(write_capabilities));
247 		if (err)
248 			return err;
249 	}
250 
251 	return got_pkt_writepkt(outfd, buf, len + capalen, chattygot);
252 }
253 
254 static void
255 echo_error(const struct got_error *err, int outfd, int chattygot)
256 {
257 	char buf[4 + GOT_ERR_MAX_MSG_SIZE];
258 	size_t len;
259 
260 	/*
261 	 * Echo the error to the client on a pkt-line.
262 	 * The client should then terminate its session.
263 	 */
264 	buf[0] = 'E'; buf[1] = 'R'; buf[2] = 'R'; buf[3] = ' '; buf[4] = '\0';
265 	len = strlcat(buf, err->msg, sizeof(buf));
266 	got_pkt_writepkt(outfd, buf, len, chattygot);
267 }
268 
269 static const struct got_error *
270 announce_refs(int outfd, struct imsgbuf *ibuf, int client_is_reading,
271     const char *repo_path, int chattygot)
272 {
273 	const struct got_error *err = NULL;
274 	struct imsg imsg;
275 	size_t datalen;
276 	struct gotd_imsg_list_refs lsref;
277 	struct gotd_imsg_reflist ireflist;
278 	struct gotd_imsg_ref iref;
279 	struct gotd_imsg_symref isymref;
280 	size_t nrefs = 0;
281 	int have_nrefs = 0, sent_capabilities = 0;
282 	char *symrefname = NULL, *symreftarget = NULL, *symrefstr = NULL;
283 	char *refname = NULL;
284 
285 	memset(&imsg, 0, sizeof(imsg));
286 	memset(&lsref, 0, sizeof(lsref));
287 
288 	if (strlcpy(lsref.repo_name, repo_path, sizeof(lsref.repo_name)) >=
289 	    sizeof(lsref.repo_name))
290 		return got_error(GOT_ERR_NO_SPACE);
291 	lsref.client_is_reading = client_is_reading;
292 
293 	if (imsg_compose(ibuf, GOTD_IMSG_LIST_REFS, 0, 0, -1,
294 	    &lsref, sizeof(lsref)) == -1)
295 		return got_error_from_errno("imsg_compose LIST_REFS");
296 
297 	err = gotd_imsg_flush(ibuf);
298 	if (err)
299 		return err;
300 
301 	while (!have_nrefs || nrefs > 0) {
302 		err = gotd_imsg_poll_recv(&imsg, ibuf, 0);
303 		if (err)
304 			goto done;
305 		datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
306 		switch (imsg.hdr.type) {
307 		case GOTD_IMSG_ERROR:
308 			err = gotd_imsg_recv_error(NULL, &imsg);
309 			goto done;
310 		case GOTD_IMSG_REFLIST:
311 			if (have_nrefs || nrefs > 0) {
312 				err = got_error(GOT_ERR_PRIVSEP_MSG);
313 				goto done;
314 			}
315 			if (datalen != sizeof(ireflist)) {
316 				err = got_error(GOT_ERR_PRIVSEP_MSG);
317 				goto done;
318 			}
319 			memcpy(&ireflist, imsg.data, sizeof(ireflist));
320 			nrefs = ireflist.nrefs;
321 			have_nrefs = 1;
322 			if (nrefs == 0)
323 				err = send_zero_refs(outfd, client_is_reading,
324 				    chattygot);
325 			break;
326 		case GOTD_IMSG_REF:
327 			if (!have_nrefs || nrefs == 0) {
328 				err = got_error(GOT_ERR_PRIVSEP_MSG);
329 				goto done;
330 			}
331 			if (datalen < sizeof(iref)) {
332 				err = got_error(GOT_ERR_PRIVSEP_MSG);
333 				goto done;
334 			}
335 			memcpy(&iref, imsg.data, sizeof(iref));
336 			if (datalen != sizeof(iref) + iref.name_len) {
337 				err = got_error(GOT_ERR_PRIVSEP_LEN);
338 				goto done;
339 			}
340 			refname = strndup(imsg.data + sizeof(iref),
341 			    iref.name_len);
342 			if (refname == NULL) {
343 				err = got_error_from_errno("strndup");
344 				goto done;
345 			}
346 			err = send_ref(outfd, iref.id, refname,
347 			    !sent_capabilities, client_is_reading,
348 			    NULL, chattygot);
349 			free(refname);
350 			refname = NULL;
351 			if (err)
352 				goto done;
353 			sent_capabilities = 1;
354 			if (nrefs > 0)
355 				nrefs--;
356 			break;
357 		case GOTD_IMSG_SYMREF:
358 			if (!have_nrefs || nrefs == 0) {
359 				err = got_error(GOT_ERR_PRIVSEP_MSG);
360 				goto done;
361 			}
362 			if (datalen < sizeof(isymref)) {
363 				err = got_error(GOT_ERR_PRIVSEP_LEN);
364 				goto done;
365 			}
366 			memcpy(&isymref, imsg.data, sizeof(isymref));
367 			if (datalen != sizeof(isymref) + isymref.name_len +
368 			    isymref.target_len) {
369 				err = got_error(GOT_ERR_PRIVSEP_LEN);
370 				goto done;
371 			}
372 
373 			/*
374 			 * For now, we only announce one symbolic ref,
375 			 * as part of our capability advertisement.
376 			 */
377 			if (sent_capabilities || symrefstr != NULL ||
378 			    symrefname != NULL || symreftarget != NULL)
379 				break;
380 
381 			symrefname = strndup(imsg.data + sizeof(isymref),
382 			    isymref.name_len);
383 			if (symrefname == NULL) {
384 				err = got_error_from_errno("malloc");
385 				goto done;
386 			}
387 
388 			symreftarget = strndup(
389 			    imsg.data + sizeof(isymref) + isymref.name_len,
390 			    isymref.target_len);
391 			if (symreftarget == NULL) {
392 				err = got_error_from_errno("strndup");
393 				goto done;
394 			}
395 
396 			if (asprintf(&symrefstr, "%s:%s", symrefname,
397 			    symreftarget) == -1) {
398 				err = got_error_from_errno("asprintf");
399 				goto done;
400 			}
401 			err = send_ref(outfd, isymref.target_id, symrefname,
402 			    !sent_capabilities, client_is_reading, symrefstr,
403 			    chattygot);
404 			free(refname);
405 			refname = NULL;
406 			if (err)
407 				goto done;
408 			sent_capabilities = 1;
409 			if (nrefs > 0)
410 				nrefs--;
411 			break;
412 		default:
413 			err = got_error(GOT_ERR_PRIVSEP_MSG);
414 			break;
415 		}
416 
417 		imsg_free(&imsg);
418 	}
419 
420 	err = got_pkt_flushpkt(outfd, chattygot);
421 	if (err)
422 		goto done;
423 done:
424 	free(symrefstr);
425 	free(symrefname);
426 	free(symreftarget);
427 	return err;
428 }
429 
430 static const struct got_error *
431 parse_want_line(char **common_capabilities, uint8_t *id, char *buf, size_t len)
432 {
433 	const struct got_error *err;
434 	char *id_str = NULL, *client_capabilities = NULL;
435 
436 	err = got_gitproto_parse_want_line(&id_str,
437 	    &client_capabilities, buf, len);
438 	if (err)
439 		return err;
440 
441 	if (!got_parse_sha1_digest(id, id_str)) {
442 		err = got_error_msg(GOT_ERR_BAD_PACKET,
443 		    "want-line with bad object ID");
444 		goto done;
445 	}
446 
447 	if (client_capabilities) {
448 		err = got_gitproto_match_capabilities(common_capabilities,
449 		    NULL, client_capabilities, read_capabilities,
450 		    nitems(read_capabilities));
451 		if (err)
452 			goto done;
453 	}
454 done:
455 	free(id_str);
456 	free(client_capabilities);
457 	return err;
458 }
459 
460 static const struct got_error *
461 parse_have_line(uint8_t *id, char *buf, size_t len)
462 {
463 	const struct got_error *err;
464 	char *id_str = NULL;
465 
466 	err = got_gitproto_parse_have_line(&id_str, buf, len);
467 	if (err)
468 		return err;
469 
470 	if (!got_parse_sha1_digest(id, id_str)) {
471 		err = got_error_msg(GOT_ERR_BAD_PACKET,
472 		    "have-line with bad object ID");
473 		goto done;
474 	}
475 done:
476 	free(id_str);
477 	return err;
478 }
479 
480 static const struct got_error *
481 send_capability(struct got_capability *capa, struct imsgbuf *ibuf)
482 {
483 	const struct got_error *err = NULL;
484 	struct gotd_imsg_capability icapa;
485 	size_t len;
486 	struct ibuf *wbuf;
487 
488 	memset(&icapa, 0, sizeof(icapa));
489 
490 	icapa.key_len = strlen(capa->key);
491 	len = sizeof(icapa) + icapa.key_len;
492 	if (capa->value) {
493 		icapa.value_len = strlen(capa->value);
494 		len += icapa.value_len;
495 	}
496 
497 	wbuf = imsg_create(ibuf, GOTD_IMSG_CAPABILITY, 0, 0, len);
498 	if (wbuf == NULL) {
499 		err = got_error_from_errno("imsg_create CAPABILITY");
500 		return err;
501 	}
502 
503 	if (imsg_add(wbuf, &icapa, sizeof(icapa)) == -1)
504 		return got_error_from_errno("imsg_add CAPABILITY");
505 	if (imsg_add(wbuf, capa->key, icapa.key_len) == -1)
506 		return got_error_from_errno("imsg_add CAPABILITY");
507 	if (capa->value) {
508 		if (imsg_add(wbuf, capa->value, icapa.value_len) == -1)
509 			return got_error_from_errno("imsg_add CAPABILITY");
510 	}
511 
512 	wbuf->fd = -1;
513 	imsg_close(ibuf, wbuf);
514 
515 	return NULL;
516 }
517 
518 static const struct got_error *
519 send_capabilities(int *use_sidebands, int *report_status,
520     char *capabilities_str, struct imsgbuf *ibuf)
521 {
522 	const struct got_error *err = NULL;
523 	struct gotd_imsg_capabilities icapas;
524 	struct got_capability *capa = NULL;
525 	size_t ncapa, i;
526 
527 	err = got_gitproto_split_capabilities_str(&capa, &ncapa,
528 	    capabilities_str);
529 	if (err)
530 		return err;
531 
532 	icapas.ncapabilities = ncapa;
533 	if (imsg_compose(ibuf, GOTD_IMSG_CAPABILITIES, 0, 0, -1,
534 	    &icapas, sizeof(icapas)) == -1) {
535 		err = got_error_from_errno("imsg_compose IMSG_CAPABILITIES");
536 		goto done;
537 	}
538 
539 	for (i = 0; i < ncapa; i++) {
540 		err = send_capability(&capa[i], ibuf);
541 		if (err)
542 			goto done;
543 		if (use_sidebands &&
544 		    strcmp(capa[i].key, GOT_CAPA_SIDE_BAND_64K) == 0)
545 			*use_sidebands = 1;
546 		if (report_status &&
547 		    strcmp(capa[i].key, GOT_CAPA_REPORT_STATUS) == 0)
548 			*report_status = 1;
549 	}
550 done:
551 	free(capa);
552 	return err;
553 }
554 
555 static const struct got_error *
556 forward_flushpkt(struct imsgbuf *ibuf)
557 {
558 	if (imsg_compose(ibuf, GOTD_IMSG_FLUSH, 0, 0, -1, NULL, 0) == -1)
559 		return got_error_from_errno("imsg_compose FLUSH");
560 
561 	return gotd_imsg_flush(ibuf);
562 }
563 
564 static const struct got_error *
565 recv_ack(struct imsg *imsg, uint8_t *expected_id)
566 {
567 	struct gotd_imsg_ack iack;
568 	size_t datalen;
569 
570 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
571 	if (datalen != sizeof(iack))
572 		return got_error(GOT_ERR_PRIVSEP_LEN);
573 
574 	memcpy(&iack, imsg->data, sizeof(iack));
575 	if (memcmp(iack.object_id, expected_id, SHA1_DIGEST_LENGTH) != 0)
576 		return got_error(GOT_ERR_BAD_OBJ_ID);
577 
578 	return NULL;
579 }
580 
581 static const struct got_error *
582 recv_nak(struct imsg *imsg, uint8_t *expected_id)
583 {
584 	struct gotd_imsg_ack inak;
585 	size_t datalen;
586 
587 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
588 	if (datalen != sizeof(inak))
589 		return got_error(GOT_ERR_PRIVSEP_LEN);
590 
591 	memcpy(&inak, imsg->data, sizeof(inak));
592 	if (memcmp(inak.object_id, expected_id, SHA1_DIGEST_LENGTH) != 0)
593 		return got_error(GOT_ERR_BAD_OBJ_ID);
594 
595 	return NULL;
596 }
597 
598 
599 static const struct got_error *
600 recv_want(int *use_sidebands, int outfd, struct imsgbuf *ibuf,
601     char *buf, size_t len, int expect_capabilities, int chattygot)
602 {
603 	const struct got_error *err;
604 	struct gotd_imsg_want iwant;
605 	char *capabilities_str;
606 	int done = 0;
607 	struct imsg imsg;
608 
609 	memset(&iwant, 0, sizeof(iwant));
610 	memset(&imsg, 0, sizeof(imsg));
611 
612 	err = parse_want_line(&capabilities_str, iwant.object_id, buf, len);
613 	if (err)
614 		return err;
615 
616 	if (capabilities_str) {
617 		if (!expect_capabilities) {
618 			err = got_error_msg(GOT_ERR_BAD_PACKET,
619 			    "unexpected capability announcement received");
620 			goto done;
621 		}
622 		err = send_capabilities(use_sidebands, NULL, capabilities_str,
623 		    ibuf);
624 		if (err)
625 			goto done;
626 
627 	}
628 
629 	if (imsg_compose(ibuf, GOTD_IMSG_WANT, 0, 0, -1,
630 	    &iwant, sizeof(iwant)) == -1) {
631 		err = got_error_from_errno("imsg_compose WANT");
632 		goto done;
633 	}
634 
635 	err = gotd_imsg_flush(ibuf);
636 	if (err)
637 		goto done;
638 
639 	/*
640 	 * Wait for an ACK, or an error in case the desired object
641 	 * does not exist.
642 	 */
643 	while (!done && err == NULL) {
644 		err = gotd_imsg_poll_recv(&imsg, ibuf, 0);
645 		if (err)
646 			break;
647 		switch (imsg.hdr.type) {
648 		case GOTD_IMSG_ERROR:
649 			err = gotd_imsg_recv_error(NULL, &imsg);
650 			break;
651 		case GOTD_IMSG_ACK:
652 			err = recv_ack(&imsg, iwant.object_id);
653 			if (err)
654 				break;
655 			done = 1;
656 			break;
657 		default:
658 			err = got_error(GOT_ERR_PRIVSEP_MSG);
659 			break;
660 		}
661 
662 		imsg_free(&imsg);
663 	}
664 done:
665 	free(capabilities_str);
666 	return err;
667 }
668 
669 static const struct got_error *
670 send_ack(int outfd, uint8_t *id, int chattygot)
671 {
672 	char hex[SHA1_DIGEST_STRING_LENGTH];
673 	char buf[GOT_PKT_MAX];
674 	int len;
675 
676 	if (got_sha1_digest_to_str(id, hex, sizeof(hex)) == NULL)
677 		return got_error(GOT_ERR_BAD_OBJ_ID);
678 
679 	len = snprintf(buf, sizeof(buf), "ACK %s\n", hex);
680 	if (len >= sizeof(buf))
681 		return got_error(GOT_ERR_NO_SPACE);
682 
683 	return got_pkt_writepkt(outfd, buf, len, chattygot);
684 }
685 
686 static const struct got_error *
687 send_nak(int outfd, int chattygot)
688 {
689 	char buf[5];
690 	int len;
691 
692 	len = snprintf(buf, sizeof(buf), "NAK\n");
693 	if (len >= sizeof(buf))
694 		return got_error(GOT_ERR_NO_SPACE);
695 
696 	return got_pkt_writepkt(outfd, buf, len, chattygot);
697 }
698 
699 static const struct got_error *
700 recv_have(int *have_ack, int outfd, struct imsgbuf *ibuf, char *buf,
701     size_t len, int chattygot)
702 {
703 	const struct got_error *err;
704 	struct gotd_imsg_have ihave;
705 	int done = 0;
706 	struct imsg imsg;
707 
708 	memset(&ihave, 0, sizeof(ihave));
709 	memset(&imsg, 0, sizeof(imsg));
710 
711 	err = parse_have_line(ihave.object_id, buf, len);
712 	if (err)
713 		return err;
714 
715 	if (imsg_compose(ibuf, GOTD_IMSG_HAVE, 0, 0, -1,
716 	    &ihave, sizeof(ihave)) == -1)
717 		return got_error_from_errno("imsg_compose HAVE");
718 
719 	err = gotd_imsg_flush(ibuf);
720 	if (err)
721 		return err;
722 
723 	/*
724 	 * Wait for an ACK or a NAK, indicating whether a common
725 	 * commit object has been found.
726 	 */
727 	while (!done && err == NULL) {
728 		err = gotd_imsg_poll_recv(&imsg, ibuf, 0);
729 		if (err)
730 			return err;
731 		switch (imsg.hdr.type) {
732 		case GOTD_IMSG_ERROR:
733 			err = gotd_imsg_recv_error(NULL, &imsg);
734 			break;
735 		case GOTD_IMSG_ACK:
736 			err = recv_ack(&imsg, ihave.object_id);
737 			if (err)
738 				break;
739 			if (!*have_ack) {
740 				err = send_ack(outfd, ihave.object_id,
741 				    chattygot);
742 				if (err)
743 					return err;
744 				*have_ack = 1;
745 			}
746 			done = 1;
747 			break;
748 		case GOTD_IMSG_NAK:
749 			err = recv_nak(&imsg, ihave.object_id);
750 			if (err)
751 				break;
752 			done = 1;
753 			break;
754 		default:
755 			err = got_error(GOT_ERR_PRIVSEP_MSG);
756 			break;
757 		}
758 
759 		imsg_free(&imsg);
760 	}
761 
762 	return err;
763 }
764 
765 static const struct got_error *
766 recv_done(int *packfd, int outfd, struct imsgbuf *ibuf, int chattygot)
767 {
768 	const struct got_error *err;
769 	struct imsg imsg;
770 
771 	*packfd = -1;
772 
773 	if (imsg_compose(ibuf, GOTD_IMSG_DONE, 0, 0, -1, NULL, 0) == -1)
774 		return got_error_from_errno("imsg_compose DONE");
775 
776 	err = gotd_imsg_flush(ibuf);
777 	if (err)
778 		return err;
779 
780 	while (*packfd == -1 && err == NULL) {
781 		err = gotd_imsg_poll_recv(&imsg, ibuf, 0);
782 		if (err)
783 			break;
784 
785 		switch (imsg.hdr.type) {
786 		case GOTD_IMSG_ERROR:
787 			err = gotd_imsg_recv_error(NULL, &imsg);
788 			break;
789 		case GOTD_IMSG_PACKFILE_PIPE:
790 			if (imsg.fd != -1)
791 				*packfd = imsg.fd;
792 			else
793 				err = got_error(GOT_ERR_PRIVSEP_NO_FD);
794 			break;
795 		default:
796 			err = got_error(GOT_ERR_PRIVSEP_MSG);
797 			break;
798 		}
799 
800 		imsg_free(&imsg);
801 	}
802 
803 	return err;
804 }
805 
806 static const struct got_error *
807 relay_progress_reports(struct imsgbuf *ibuf, int outfd, int chattygot)
808 {
809 	const struct got_error *err = NULL;
810 	int pack_starting = 0;
811 	struct gotd_imsg_packfile_progress iprog;
812 	char buf[GOT_PKT_MAX];
813 	struct imsg imsg;
814 	size_t datalen;
815 	int p_deltify = 0, n;
816 	const char *eol = "\r";
817 
818 	memset(&imsg, 0, sizeof(imsg));
819 
820 	while (!pack_starting && err == NULL) {
821 		err = gotd_imsg_poll_recv(&imsg, ibuf, 0);
822 		if (err)
823 			break;
824 
825 		datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
826 		switch (imsg.hdr.type) {
827 		case GOTD_IMSG_ERROR:
828 			err = gotd_imsg_recv_error(NULL, &imsg);
829 			break;
830 		case GOTD_IMSG_PACKFILE_READY:
831 			eol = "\n";
832 			pack_starting = 1;
833 			/* fallthrough */
834 		case GOTD_IMSG_PACKFILE_PROGRESS:
835 			if (datalen != sizeof(iprog)) {
836 				err = got_error(GOT_ERR_PRIVSEP_LEN);
837 				break;
838 			}
839 			memcpy(&iprog, imsg.data, sizeof(iprog));
840 			if (iprog.nobj_total > 0) {
841 				p_deltify = (iprog.nobj_deltify * 100) /
842 				    iprog.nobj_total;
843 			}
844 			buf[0] = GOT_SIDEBAND_PROGRESS_INFO;
845 			n = snprintf(&buf[1], sizeof(buf) - 1,
846 			    "%d commits colored, "
847 			    "%d objects found, "
848 			    "deltify %d%%%s",
849 			    iprog.ncolored,
850 			    iprog.nfound,
851 			    p_deltify, eol);
852 			if (n >= sizeof(buf) - 1)
853 				break;
854 			err = got_pkt_writepkt(outfd, buf, 1 + n, chattygot);
855 			break;
856 		default:
857 			err = got_error(GOT_ERR_PRIVSEP_MSG);
858 			break;
859 		}
860 
861 		imsg_free(&imsg);
862 	}
863 
864 	return err;
865 }
866 
867 static const struct got_error *
868 serve_read(int infd, int outfd, int gotd_sock, const char *repo_path,
869     int chattygot)
870 {
871 	const struct got_error *err = NULL;
872 	char buf[GOT_PKT_MAX];
873 	struct imsgbuf ibuf;
874 	enum protostate {
875 		STATE_EXPECT_WANT,
876 		STATE_EXPECT_MORE_WANT,
877 		STATE_EXPECT_HAVE,
878 		STATE_EXPECT_DONE,
879 		STATE_DONE,
880 	};
881 	enum protostate curstate = STATE_EXPECT_WANT;
882 	int have_ack = 0, use_sidebands = 0, seen_have = 0;
883 	int packfd = -1;
884 	size_t pack_chunksize;
885 
886 	imsg_init(&ibuf, gotd_sock);
887 
888 	err = announce_refs(outfd, &ibuf, 1, repo_path, chattygot);
889 	if (err)
890 		goto done;
891 
892 	while (curstate != STATE_DONE) {
893 		int n;
894 		buf[0] = '\0';
895 		err = got_pkt_readpkt(&n, infd, buf, sizeof(buf), chattygot);
896 		if (err)
897 			goto done;
898 		if (n == 0) {
899 			if (curstate != STATE_EXPECT_WANT &&
900 			    curstate != STATE_EXPECT_MORE_WANT &&
901 			    curstate != STATE_EXPECT_HAVE &&
902 			    curstate != STATE_EXPECT_DONE) {
903 				err = got_error_msg(GOT_ERR_BAD_PACKET,
904 				    "unexpected flush packet received");
905 				goto done;
906 			}
907 
908 			if (curstate == STATE_EXPECT_WANT) {
909 				ssize_t r;
910 				/*
911 				 * If the client does not want to fetch
912 				 * anything we should receive a flush
913 				 * packet followed by EOF.
914 				 */
915 				r = read(infd, buf, sizeof(buf));
916 				if (r == -1) {
917 					err = got_error_from_errno("read");
918 					goto done;
919 				}
920 				if (r == 0) /* EOF */
921 					goto done;
922 
923 				/* Zero-length field followed by payload. */
924 				err = got_error_msg(GOT_ERR_BAD_PACKET,
925 				    "unexpected flush packet received");
926 				goto done;
927 			}
928 
929 			if (curstate == STATE_EXPECT_WANT ||
930 			    curstate == STATE_EXPECT_MORE_WANT ||
931 			    curstate == STATE_EXPECT_HAVE) {
932 				err = forward_flushpkt(&ibuf);
933 				if (err)
934 					goto done;
935 			}
936 			if (curstate == STATE_EXPECT_HAVE && !have_ack) {
937 				err = send_nak(outfd, chattygot);
938 				if (err)
939 					goto done;
940 			}
941 			if (curstate == STATE_EXPECT_MORE_WANT)
942 				curstate = STATE_EXPECT_HAVE;
943 			else
944 				curstate = STATE_EXPECT_DONE;
945 		} else if (n >= 5 && strncmp(buf, "want ", 5) == 0) {
946 			if (curstate != STATE_EXPECT_WANT &&
947 			    curstate != STATE_EXPECT_MORE_WANT) {
948 				err = got_error_msg(GOT_ERR_BAD_PACKET,
949 				    "unexpected 'want' packet");
950 				goto done;
951 			}
952 			err = recv_want(&use_sidebands, outfd, &ibuf, buf, n,
953 			    curstate == STATE_EXPECT_WANT ? 1 : 0, chattygot);
954 			if (err)
955 				goto done;
956 			if (curstate == STATE_EXPECT_WANT)
957 				curstate = STATE_EXPECT_MORE_WANT;
958 		} else if (n >= 5 && strncmp(buf, "have ", 5) == 0) {
959 			if (curstate != STATE_EXPECT_HAVE &&
960 			    curstate != STATE_EXPECT_DONE) {
961 				err = got_error_msg(GOT_ERR_BAD_PACKET,
962 				    "unexpected 'have' packet");
963 				goto done;
964 			}
965 			if (curstate == STATE_EXPECT_HAVE) {
966 				err = recv_have(&have_ack, outfd, &ibuf,
967 				    buf, n, chattygot);
968 				if (err)
969 					goto done;
970 				seen_have = 1;
971 				if (have_ack)
972 					curstate = STATE_EXPECT_DONE;
973 			}
974 		} else if (n == 5 && strncmp(buf, "done\n", 5) == 0) {
975 			if (curstate != STATE_EXPECT_HAVE &&
976 			    curstate != STATE_EXPECT_DONE) {
977 				err = got_error_msg(GOT_ERR_BAD_PACKET,
978 				    "unexpected 'done' packet");
979 				goto done;
980 			}
981 			err = recv_done(&packfd, outfd, &ibuf, chattygot);
982 			if (err)
983 				goto done;
984 			curstate = STATE_DONE;
985 			break;
986 		} else {
987 			err = got_error(GOT_ERR_BAD_PACKET);
988 			goto done;
989 		}
990 	}
991 
992 	if (!seen_have) {
993 		err = send_nak(outfd, chattygot);
994 		if (err)
995 			goto done;
996 	}
997 
998 	if (use_sidebands) {
999 		err = relay_progress_reports(&ibuf, outfd, chattygot);
1000 		if (err)
1001 			goto done;
1002 		pack_chunksize = GOT_SIDEBAND_64K_PACKFILE_DATA_MAX;
1003 	} else
1004 		pack_chunksize = sizeof(buf);
1005 
1006 	for (;;) {
1007 		ssize_t r;
1008 
1009 		r = read(packfd, use_sidebands ? &buf[1] : buf,
1010 		    pack_chunksize);
1011 		if (r == -1) {
1012 			err = got_error_from_errno("read");
1013 			break;
1014 		} else if (r == 0) {
1015 			err = got_pkt_flushpkt(outfd, chattygot);
1016 			break;
1017 		}
1018 
1019 		if (use_sidebands) {
1020 			buf[0] = GOT_SIDEBAND_PACKFILE_DATA;
1021 			err = got_pkt_writepkt(outfd, buf, 1 + r, chattygot);
1022 			if (err)
1023 				break;
1024 		} else {
1025 			err = got_poll_write_full(outfd, buf, r);
1026 			if (err) {
1027 				if (err->code == GOT_ERR_EOF)
1028 					err = NULL;
1029 				break;
1030 			}
1031 		}
1032 	}
1033 done:
1034 	imsg_clear(&ibuf);
1035 	if (packfd != -1 && close(packfd) == -1 && err == NULL)
1036 		err = got_error_from_errno("close");
1037 	if (err)
1038 		echo_error(err, outfd, chattygot);
1039 	return err;
1040 }
1041 
1042 static const struct got_error *
1043 parse_ref_update_line(char **common_capabilities, char **refname,
1044     uint8_t *old_id, uint8_t *new_id, char *buf, size_t len)
1045 {
1046 	const struct got_error *err;
1047 	char *old_id_str = NULL, *new_id_str = NULL;
1048 	char *client_capabilities = NULL;
1049 
1050 	*refname = NULL;
1051 
1052 	err = got_gitproto_parse_ref_update_line(&old_id_str, &new_id_str,
1053 	    refname, &client_capabilities, buf, len);
1054 	if (err)
1055 		return err;
1056 
1057 	if (!got_parse_sha1_digest(old_id, old_id_str) ||
1058 	    !got_parse_sha1_digest(new_id, new_id_str)) {
1059 		err = got_error_msg(GOT_ERR_BAD_PACKET,
1060 		    "ref-update with bad object ID");
1061 		goto done;
1062 	}
1063 	if (!got_ref_name_is_valid(*refname)) {
1064 		err = got_error_msg(GOT_ERR_BAD_PACKET,
1065 		    "ref-update with bad reference name");
1066 		goto done;
1067 	}
1068 
1069 	if (client_capabilities) {
1070 		err = got_gitproto_match_capabilities(common_capabilities,
1071 		    NULL, client_capabilities, write_capabilities,
1072 		    nitems(write_capabilities));
1073 		if (err)
1074 			goto done;
1075 	}
1076 done:
1077 	free(old_id_str);
1078 	free(new_id_str);
1079 	free(client_capabilities);
1080 	if (err) {
1081 		free(*refname);
1082 		*refname = NULL;
1083 	}
1084 	return err;
1085 }
1086 
1087 static const struct got_error *
1088 recv_ref_update(int *report_status, int outfd, struct imsgbuf *ibuf,
1089     char *buf, size_t len, int expect_capabilities, int chattygot)
1090 {
1091 	const struct got_error *err;
1092 	struct gotd_imsg_ref_update iref;
1093 	struct ibuf *wbuf;
1094 	char *capabilities_str = NULL, *refname = NULL;
1095 	int done = 0;
1096 	struct imsg imsg;
1097 
1098 	memset(&iref, 0, sizeof(iref));
1099 	memset(&imsg, 0, sizeof(imsg));
1100 
1101 	err = parse_ref_update_line(&capabilities_str, &refname,
1102 	    iref.old_id, iref.new_id, buf, len);
1103 	if (err)
1104 		return err;
1105 
1106 	if (capabilities_str) {
1107 		if (!expect_capabilities) {
1108 			err = got_error_msg(GOT_ERR_BAD_PACKET,
1109 			    "unexpected capability announcement received");
1110 			goto done;
1111 		}
1112 		err = send_capabilities(NULL, report_status, capabilities_str,
1113 		    ibuf);
1114 		if (err)
1115 			goto done;
1116 	}
1117 
1118 	iref.name_len = strlen(refname);
1119 	len = sizeof(iref) + iref.name_len;
1120 	wbuf = imsg_create(ibuf, GOTD_IMSG_REF_UPDATE, 0, 0, len);
1121 	if (wbuf == NULL) {
1122 		err = got_error_from_errno("imsg_create REF_UPDATE");
1123 		goto done;
1124 	}
1125 
1126 	if (imsg_add(wbuf, &iref, sizeof(iref)) == -1)
1127 		return got_error_from_errno("imsg_add REF_UPDATE");
1128 	if (imsg_add(wbuf, refname, iref.name_len) == -1)
1129 		return got_error_from_errno("imsg_add REF_UPDATE");
1130 	wbuf->fd = -1;
1131 	imsg_close(ibuf, wbuf);
1132 
1133 	err = gotd_imsg_flush(ibuf);
1134 	if (err)
1135 		goto done;
1136 
1137 	/* Wait for ACK or an error. */
1138 	while (!done && err == NULL) {
1139 		err = gotd_imsg_poll_recv(&imsg, ibuf, 0);
1140 		if (err)
1141 			break;
1142 		switch (imsg.hdr.type) {
1143 		case GOTD_IMSG_ERROR:
1144 			err = gotd_imsg_recv_error(NULL, &imsg);
1145 			break;
1146 		case GOTD_IMSG_ACK:
1147 			err = recv_ack(&imsg, iref.new_id);
1148 			if (err)
1149 				break;
1150 			done = 1;
1151 			break;
1152 		default:
1153 			err = got_error(GOT_ERR_PRIVSEP_MSG);
1154 			break;
1155 		}
1156 
1157 		imsg_free(&imsg);
1158 	}
1159 done:
1160 	free(capabilities_str);
1161 	free(refname);
1162 	return err;
1163 }
1164 
1165 static const struct got_error *
1166 recv_packfile(struct imsg *imsg, int infd)
1167 {
1168 	const struct got_error *err = NULL;
1169 	size_t datalen;
1170 	int packfd;
1171 	char buf[GOT_PKT_MAX];
1172 	int pack_done = 0;
1173 
1174 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
1175 	if (datalen != 0)
1176 		return got_error(GOT_ERR_PRIVSEP_MSG);
1177 
1178 	if (imsg->fd == -1)
1179 		return got_error(GOT_ERR_PRIVSEP_NO_FD);
1180 
1181 	packfd = imsg->fd;
1182 	while (!pack_done) {
1183 		ssize_t r = 0;
1184 
1185 		err = got_poll_fd(infd, POLLIN, 1);
1186 		if (err) {
1187 			if (err->code != GOT_ERR_TIMEOUT)
1188 				break;
1189 			err = NULL;
1190 		} else {
1191 			r = read(infd, buf, sizeof(buf));
1192 			if (r == -1) {
1193 				err = got_error_from_errno("read");
1194 				break;
1195 			}
1196 			if (r == 0) {
1197 				/*
1198 				 * Git clients hang up their side of the
1199 				 * connection after sending the pack file.
1200 				 */
1201 				err = NULL;
1202 				pack_done = 1;
1203 				break;
1204 			}
1205 		}
1206 
1207 		if (r == 0) {
1208 			/* Detect gotd(8) closing the pack pipe when done. */
1209 			err = got_poll_fd(packfd, POLLOUT, 1);
1210 			if (err) {
1211 				if (err->code != GOT_ERR_EOF)
1212 					break;
1213 				err = NULL;
1214 				pack_done = 1;
1215 			}
1216 		} else {
1217 			/* Write pack data and/or detect pipe being closed. */
1218 			err = got_poll_write_full(packfd, buf, r);
1219 			if (err) {
1220 				if (err->code == GOT_ERR_EOF)
1221 					err = NULL;
1222 				break;
1223 			}
1224 		}
1225 	}
1226 
1227 	close(packfd);
1228 	return err;
1229 }
1230 
1231 static const struct got_error *
1232 report_unpack_status(struct imsg *imsg, int outfd, int chattygot)
1233 {
1234 	const struct got_error *err = NULL;
1235 	struct gotd_imsg_packfile_status istatus;
1236 	char buf[GOT_PKT_MAX];
1237 	size_t datalen, len;
1238 	char *reason = NULL;
1239 
1240 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
1241 	if (datalen < sizeof(istatus))
1242 		return got_error(GOT_ERR_PRIVSEP_LEN);
1243 	memcpy(&istatus, imsg->data, sizeof(istatus));
1244 	if (datalen != sizeof(istatus) + istatus.reason_len)
1245 		return got_error(GOT_ERR_PRIVSEP_LEN);
1246 
1247 	reason = strndup(imsg->data + sizeof(istatus), istatus.reason_len);
1248 	if (reason == NULL) {
1249 		err = got_error_from_errno("strndup");
1250 		goto done;
1251 	}
1252 
1253 	if (err == NULL)
1254 		len = snprintf(buf, sizeof(buf), "unpack ok\n");
1255 	else
1256 		len = snprintf(buf, sizeof(buf), "unpack %s\n", reason);
1257 	if (len >= sizeof(buf)) {
1258 		err = got_error(GOT_ERR_NO_SPACE);
1259 		goto done;
1260 	}
1261 
1262 	err = got_pkt_writepkt(outfd, buf, len, chattygot);
1263 done:
1264 	free(reason);
1265 	return err;
1266 }
1267 
1268 static const struct got_error *
1269 recv_ref_update_ok(struct imsg *imsg, int outfd, int chattygot)
1270 {
1271 	const struct got_error *err = NULL;
1272 	struct gotd_imsg_ref_update_ok iok;
1273 	size_t datalen, len;
1274 	char buf[GOT_PKT_MAX];
1275 	char *refname = NULL;
1276 
1277 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
1278 	if (datalen < sizeof(iok))
1279 		return got_error(GOT_ERR_PRIVSEP_LEN);
1280 	memcpy(&iok, imsg->data, sizeof(iok));
1281 	if (datalen != sizeof(iok) + iok.name_len)
1282 		return got_error(GOT_ERR_PRIVSEP_LEN);
1283 
1284 	memcpy(&iok, imsg->data, sizeof(iok));
1285 
1286 	refname = strndup(imsg->data + sizeof(iok), iok.name_len);
1287 	if (refname == NULL)
1288 		return got_error_from_errno("strndup");
1289 
1290 	len = snprintf(buf, sizeof(buf), "ok %s\n", refname);
1291 	if (len >= sizeof(buf)) {
1292 		err = got_error(GOT_ERR_NO_SPACE);
1293 		goto done;
1294 	}
1295 
1296 	err = got_pkt_writepkt(outfd, buf, len, chattygot);
1297 done:
1298 	free(refname);
1299 	return err;
1300 }
1301 
1302 static const struct got_error *
1303 recv_ref_update_ng(struct imsg *imsg, int outfd, int chattygot)
1304 {
1305 	const struct got_error *err = NULL;
1306 	struct gotd_imsg_ref_update_ng ing;
1307 	size_t datalen, len;
1308 	char buf[GOT_PKT_MAX];
1309 	char *refname = NULL, *reason = NULL;
1310 
1311 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
1312 	if (datalen < sizeof(ing))
1313 		return got_error(GOT_ERR_PRIVSEP_LEN);
1314 	memcpy(&ing, imsg->data, sizeof(ing));
1315 	if (datalen != sizeof(ing) + ing.name_len + ing.reason_len)
1316 		return got_error(GOT_ERR_PRIVSEP_LEN);
1317 
1318 	memcpy(&ing, imsg->data, sizeof(ing));
1319 
1320 	refname = strndup(imsg->data + sizeof(ing), ing.name_len);
1321 	if (refname == NULL)
1322 		return got_error_from_errno("strndup");
1323 
1324 	reason = strndup(imsg->data + sizeof(ing) + ing.name_len,
1325 	    ing.reason_len);
1326 	if (reason == NULL) {
1327 		err = got_error_from_errno("strndup");
1328 		goto done;
1329 	}
1330 
1331 	len = snprintf(buf, sizeof(buf), "ng %s %s\n", refname, reason);
1332 	if (len >= sizeof(buf)) {
1333 		err = got_error(GOT_ERR_NO_SPACE);
1334 		goto done;
1335 	}
1336 
1337 	err = got_pkt_writepkt(outfd, buf, len, chattygot);
1338 done:
1339 	free(refname);
1340 	free(reason);
1341 	return err;
1342 }
1343 
1344 static const struct got_error *
1345 serve_write(int infd, int outfd, int gotd_sock, const char *repo_path,
1346     int chattygot)
1347 {
1348 	const struct got_error *err = NULL;
1349 	char buf[GOT_PKT_MAX];
1350 	struct imsgbuf ibuf;
1351 	enum protostate {
1352 		STATE_EXPECT_REF_UPDATE,
1353 		STATE_EXPECT_MORE_REF_UPDATES,
1354 		STATE_EXPECT_PACKFILE,
1355 		STATE_PACKFILE_RECEIVED,
1356 		STATE_REFS_UPDATED,
1357 	};
1358 	enum protostate curstate = STATE_EXPECT_REF_UPDATE;
1359 	struct imsg imsg;
1360 	int report_status = 0;
1361 
1362 	imsg_init(&ibuf, gotd_sock);
1363 	memset(&imsg, 0, sizeof(imsg));
1364 
1365 	err = announce_refs(outfd, &ibuf, 0, repo_path, chattygot);
1366 	if (err)
1367 		goto done;
1368 
1369 	while (curstate != STATE_EXPECT_PACKFILE) {
1370 		int n;
1371 		buf[0] = '\0';
1372 		err = got_pkt_readpkt(&n, infd, buf, sizeof(buf), chattygot);
1373 		if (err)
1374 			goto done;
1375 		if (n == 0) {
1376 			if (curstate != STATE_EXPECT_MORE_REF_UPDATES) {
1377 				err = got_error_msg(GOT_ERR_BAD_PACKET,
1378 				    "unexpected flush packet received");
1379 				goto done;
1380 			}
1381 			err = forward_flushpkt(&ibuf);
1382 			if (err)
1383 				goto done;
1384 			curstate = STATE_EXPECT_PACKFILE;
1385 		} else if (n >= (SHA1_DIGEST_STRING_LENGTH * 2) + 2) {
1386 			if (curstate != STATE_EXPECT_REF_UPDATE &&
1387 			    curstate != STATE_EXPECT_MORE_REF_UPDATES) {
1388 				err = got_error_msg(GOT_ERR_BAD_PACKET,
1389 				    "unexpected ref-update packet");
1390 				goto done;
1391 			}
1392 			if (curstate == STATE_EXPECT_REF_UPDATE) {
1393 				err = recv_ref_update(&report_status,
1394 				    outfd, &ibuf, buf, n, 1, chattygot);
1395 			} else {
1396 				err = recv_ref_update(NULL, outfd, &ibuf,
1397 				    buf, n, 0, chattygot);
1398 			}
1399 			if (err)
1400 				goto done;
1401 			curstate = STATE_EXPECT_MORE_REF_UPDATES;
1402 		} else {
1403 			err = got_error(GOT_ERR_BAD_PACKET);
1404 			goto done;
1405 		}
1406 	}
1407 
1408 	while (curstate != STATE_PACKFILE_RECEIVED) {
1409 		err = gotd_imsg_poll_recv(&imsg, &ibuf, 0);
1410 		if (err)
1411 			goto done;
1412 		switch (imsg.hdr.type) {
1413 		case GOTD_IMSG_ERROR:
1414 			err = gotd_imsg_recv_error(NULL, &imsg);
1415 			goto done;
1416 		case GOTD_IMSG_PACKFILE_PIPE:
1417 			err = recv_packfile(&imsg, infd);
1418 			if (err) {
1419 				if (err->code != GOT_ERR_EOF)
1420 					goto done;
1421 				/*
1422 				 * EOF is reported when the client hangs up,
1423 				 * which can happen with Git clients.
1424 				 * The socket should stay half-open so we
1425 				 * can still send our reports if requested.
1426 				 */
1427 				err = NULL;
1428 			}
1429 			curstate = STATE_PACKFILE_RECEIVED;
1430 			break;
1431 		default:
1432 			err = got_error(GOT_ERR_PRIVSEP_MSG);
1433 			break;
1434 		}
1435 
1436 		imsg_free(&imsg);
1437 		if (err)
1438 			goto done;
1439 	}
1440 
1441 	while (curstate != STATE_REFS_UPDATED && err == NULL) {
1442 		err = gotd_imsg_poll_recv(&imsg, &ibuf, 0);
1443 		if (err)
1444 			break;
1445 		switch (imsg.hdr.type) {
1446 		case GOTD_IMSG_ERROR:
1447 			err = gotd_imsg_recv_error(NULL, &imsg);
1448 			break;
1449 		case GOTD_IMSG_PACKFILE_STATUS:
1450 			if (!report_status)
1451 				break;
1452 			err = report_unpack_status(&imsg, outfd, chattygot);
1453 			break;
1454 		case GOTD_IMSG_REF_UPDATE_OK:
1455 			if (!report_status)
1456 				break;
1457 			err = recv_ref_update_ok(&imsg, outfd, chattygot);
1458 			break;
1459 		case GOTD_IMSG_REF_UPDATE_NG:
1460 			if (!report_status)
1461 				break;
1462 			err = recv_ref_update_ng(&imsg, outfd, chattygot);
1463 			break;
1464 		case GOTD_IMSG_REFS_UPDATED:
1465 			curstate = STATE_REFS_UPDATED;
1466 			err = got_pkt_flushpkt(outfd, chattygot);
1467 			break;
1468 		default:
1469 			err = got_error(GOT_ERR_PRIVSEP_MSG);
1470 			break;
1471 		}
1472 
1473 		imsg_free(&imsg);
1474 	}
1475 done:
1476 	imsg_clear(&ibuf);
1477 	if (err)
1478 		echo_error(err, outfd, chattygot);
1479 	return err;
1480 }
1481 
1482 const struct got_error *
1483 got_serve(int infd, int outfd, const char *command, const char *repo_path,
1484     int gotd_sock, int chattygot)
1485 {
1486 	const struct got_error *err = NULL;
1487 
1488 	if (strcmp(command, GOT_SERVE_CMD_FETCH) == 0)
1489 		err = serve_read(infd, outfd, gotd_sock, repo_path, chattygot);
1490 	else if (strcmp(command, GOT_SERVE_CMD_SEND) == 0)
1491 		err = serve_write(infd, outfd, gotd_sock, repo_path,
1492 		    chattygot);
1493 	else
1494 		err = got_error(GOT_ERR_BAD_PACKET);
1495 
1496 	return err;
1497 }