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Date:: Tue Nov 8 20:06:17 2022 UTC
Message:: fix capabilities announced by gotsh when no reference exist in repository ok op@
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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 #if 0
63 	{ GOT_CAPA_DELETE_REFS, NULL },
64 #endif
65 };
66 
67 static const struct got_error *
68 parse_command(char **command, char **repo_path, const char *gitcmd)
69 {
70 	const struct got_error *err = NULL;
71 	size_t len, cmdlen, pathlen;
72 	char *path0 = NULL, *path, *abspath = NULL, *canonpath = NULL;
73 	const char *relpath;
74 
75 	*command = NULL;
76 	*repo_path = NULL;
77 
78 	len = strlen(gitcmd);
79 
80 	if (len >= strlen(GOT_SERVE_CMD_SEND) &&
81 	    strncmp(gitcmd, GOT_SERVE_CMD_SEND,
82 	    strlen(GOT_SERVE_CMD_SEND)) == 0)
83 		cmdlen = strlen(GOT_SERVE_CMD_SEND);
84 	else if (len >= strlen(GOT_SERVE_CMD_FETCH) &&
85 	    strncmp(gitcmd, GOT_SERVE_CMD_FETCH,
86 	    strlen(GOT_SERVE_CMD_FETCH)) == 0)
87 		cmdlen = strlen(GOT_SERVE_CMD_FETCH);
88 	else
89 		return got_error(GOT_ERR_BAD_PACKET);
90 
91 	if (len <= cmdlen + 1 || gitcmd[cmdlen] != ' ')
92 		return got_error(GOT_ERR_BAD_PACKET);
93 
94 	if (memchr(&gitcmd[cmdlen + 1], '\0', len - cmdlen) == NULL)
95 		return got_error(GOT_ERR_BAD_PATH);
96 
97 	/* Forbid linefeeds in paths, like Git does. */
98 	if (memchr(&gitcmd[cmdlen + 1], '\n', len - cmdlen) != NULL)
99 		return got_error(GOT_ERR_BAD_PATH);
100 
101 	path0 = strdup(&gitcmd[cmdlen + 1]);
102 	if (path0 == NULL)
103 		return got_error_from_errno("strdup");
104 	path = path0;
105 	pathlen = strlen(path);
106 
107 	/*
108 	 * Git clients send a shell command.
109 	 * Trim spaces and quotes around the path.
110 	 */
111 	while (path[0] == '\'' || path[0] == '\"' || path[0] == ' ') {
112 		path++;
113 		pathlen--;
114 	}
115 	while (pathlen > 0 &&
116 	    (path[pathlen - 1] == '\'' || path[pathlen - 1] == '\"' ||
117 	    path[pathlen - 1] == ' ')) {
118 		path[pathlen - 1] = '\0';
119 		pathlen--;
120 	}
121 
122 	/* Deny an empty repository path. */
123 	if (path[0] == '\0' || got_path_is_root_dir(path)) {
124 		err = got_error(GOT_ERR_NOT_GIT_REPO);
125 		goto done;
126 	}
127 
128 	if (asprintf(&abspath, "/%s", path) == -1) {
129 		err = got_error_from_errno("asprintf");
130 		goto done;
131 	}
132 	pathlen = strlen(abspath);
133 	canonpath = malloc(pathlen);
134 	if (canonpath == NULL) {
135 		err = got_error_from_errno("malloc");
136 		goto done;
137 	}
138 	err = got_canonpath(abspath, canonpath, pathlen);
139 	if (err)
140 		goto done;
141 
142 	relpath = canonpath;
143 	while (relpath[0] == '/')
144 		relpath++;
145 	*repo_path = strdup(relpath);
146 	if (*repo_path == NULL) {
147 		err = got_error_from_errno("strdup");
148 		goto done;
149 	}
150 	*command = strndup(gitcmd, cmdlen);
151 	if (*command == NULL)
152 		err = got_error_from_errno("strndup");
153 done:
154 	free(path0);
155 	free(abspath);
156 	free(canonpath);
157 	if (err) {
158 		free(*repo_path);
159 		*repo_path = NULL;
160 	}
161 	return err;
162 }
163 
164 static const struct got_error *
165 append_read_capabilities(size_t *capalen, size_t len, const char *symrefstr,
166     uint8_t *buf, size_t bufsize)
167 {
168 	struct got_capability capa[nitems(read_capabilities) + 1];
169 	size_t ncapa;
170 
171 	memcpy(&capa, read_capabilities, sizeof(read_capabilities));
172 	if (symrefstr) {
173 		capa[nitems(read_capabilities)].key = "symref";
174 		capa[nitems(read_capabilities)].value = symrefstr;
175 		ncapa = nitems(capa);
176 	} else
177 		ncapa = nitems(read_capabilities);
178 
179 	return got_gitproto_append_capabilities(capalen, buf, len,
180 	    bufsize, capa, ncapa);
181 }
182 
183 static const struct got_error *
184 send_ref(int outfd, uint8_t *id, const char *refname, int send_capabilities,
185     int client_is_reading, const char *symrefstr, int chattygot)
186 {
187 	const struct got_error *err = NULL;
188 	char hex[SHA1_DIGEST_STRING_LENGTH];
189 	char buf[GOT_PKT_MAX];
190 	size_t len, capalen = 0;
191 
192 	if (got_sha1_digest_to_str(id, hex, sizeof(hex)) == NULL)
193 		return got_error(GOT_ERR_BAD_OBJ_ID);
194 
195 	len = snprintf(buf, sizeof(buf), "%s %s", hex, refname);
196 	if (len >= sizeof(buf))
197 		return got_error(GOT_ERR_NO_SPACE);
198 
199 	if (send_capabilities) {
200 		if (client_is_reading) {
201 			err = append_read_capabilities(&capalen, len,
202 			    symrefstr, buf, sizeof(buf));
203 		} else {
204 			err = got_gitproto_append_capabilities(&capalen,
205 			    buf, len, sizeof(buf), write_capabilities,
206 			    nitems(write_capabilities));
207 		}
208 		if (err)
209 			return err;
210 		len += capalen;
211 	}
212 
213 	if (len + 1 >= sizeof(buf))
214 		return got_error(GOT_ERR_NO_SPACE);
215 	buf[len] = '\n';
216 	len++;
217 	buf[len] = '\0';
218 
219 	return got_pkt_writepkt(outfd, buf, len, chattygot);
220 }
221 
222 static const struct got_error *
223 send_zero_refs(int outfd, int client_is_reading, int chattygot)
224 {
225 	const struct got_error *err = NULL;
226 	char buf[GOT_PKT_MAX];
227 	uint8_t zero[SHA1_DIGEST_LENGTH];
228 	char hex[SHA1_DIGEST_STRING_LENGTH];
229 	size_t len, capalen = 0;
230 
231 	memset(&zero, 0, sizeof(zero));
232 
233 	if (got_sha1_digest_to_str(zero, hex, sizeof(hex)) == NULL)
234 		return got_error(GOT_ERR_BAD_OBJ_ID);
235 
236 	len = snprintf(buf, sizeof(buf), "%s capabilities^{}", hex);
237 	if (len >= sizeof(buf))
238 		return got_error(GOT_ERR_NO_SPACE);
239 
240 	if (client_is_reading) {
241 		err = got_gitproto_append_capabilities(&capalen, buf, len,
242 		    sizeof(buf), read_capabilities, nitems(read_capabilities));
243 		if (err)
244 			return err;
245 	} else {
246 		err = got_gitproto_append_capabilities(&capalen, buf, len,
247 		    sizeof(buf), write_capabilities,
248 		    nitems(write_capabilities));
249 		if (err)
250 			return err;
251 	}
252 
253 	return got_pkt_writepkt(outfd, buf, len + capalen, chattygot);
254 }
255 
256 static void
257 echo_error(const struct got_error *err, int outfd, int chattygot)
258 {
259 	char buf[4 + GOT_ERR_MAX_MSG_SIZE];
260 	size_t len;
261 
262 	/*
263 	 * Echo the error to the client on a pkt-line.
264 	 * The client should then terminate its session.
265 	 */
266 	buf[0] = 'E'; buf[1] = 'R'; buf[2] = 'R'; buf[3] = ' '; buf[4] = '\0';
267 	len = strlcat(buf, err->msg, sizeof(buf));
268 	err = got_pkt_writepkt(outfd, buf, len, chattygot);
269 	abort();
270 }
271 
272 static const struct got_error *
273 announce_refs(int outfd, struct imsgbuf *ibuf, int client_is_reading,
274     const char *repo_path, int chattygot)
275 {
276 	const struct got_error *err = NULL;
277 	struct imsg imsg;
278 	size_t datalen;
279 	struct gotd_imsg_list_refs lsref;
280 	struct gotd_imsg_reflist ireflist;
281 	struct gotd_imsg_ref iref;
282 	struct gotd_imsg_symref isymref;
283 	size_t nrefs = 0;
284 	int have_nrefs = 0, sent_capabilities = 0;
285 	char *symrefname = NULL, *symreftarget = NULL, *symrefstr = NULL;
286 	char *refname = NULL;
287 
288 	memset(&imsg, 0, sizeof(imsg));
289 	memset(&lsref, 0, sizeof(lsref));
290 
291 	if (strlcpy(lsref.repo_name, repo_path, sizeof(lsref.repo_name)) >=
292 	    sizeof(lsref.repo_name))
293 		return got_error(GOT_ERR_NO_SPACE);
294 	lsref.client_is_reading = client_is_reading;
295 	
296 	if (imsg_compose(ibuf, GOTD_IMSG_LIST_REFS, 0, 0, -1,
297 	    &lsref, sizeof(lsref)) == -1)
298 		return got_error_from_errno("imsg_compose LIST_REFS");
299 
300 	err = gotd_imsg_flush(ibuf);
301 	if (err)
302 		return err;
303 
304 	while (!have_nrefs || nrefs > 0) {
305 		err = gotd_imsg_poll_recv(&imsg, ibuf, 0);
306 		if (err)
307 			goto done;
308 		datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
309 		switch (imsg.hdr.type) {
310 		case GOTD_IMSG_ERROR:
311 			err = gotd_imsg_recv_error(NULL, &imsg);
312 			goto done;
313 		case GOTD_IMSG_REFLIST:
314 			if (have_nrefs || nrefs > 0) {
315 				err = got_error(GOT_ERR_PRIVSEP_MSG);
316 				goto done;
317 			}
318 			if (datalen != sizeof(ireflist)) {
319 				err = got_error(GOT_ERR_PRIVSEP_MSG);
320 				goto done;
321 			}
322 			memcpy(&ireflist, imsg.data, sizeof(ireflist));
323 			nrefs = ireflist.nrefs;
324 			have_nrefs = 1;
325 			if (nrefs == 0)
326 				err = send_zero_refs(outfd, client_is_reading,
327 				    chattygot);
328 			break;
329 		case GOTD_IMSG_REF:
330 			if (!have_nrefs || nrefs == 0) {
331 				err = got_error(GOT_ERR_PRIVSEP_MSG);
332 				goto done;
333 			}
334 			if (datalen < sizeof(iref)) {
335 				err = got_error(GOT_ERR_PRIVSEP_MSG);
336 				goto done;
337 			}
338 			memcpy(&iref, imsg.data, sizeof(iref));
339 			if (datalen != sizeof(iref) + iref.name_len) {
340 				err = got_error(GOT_ERR_PRIVSEP_LEN);
341 				goto done;
342 			}
343 			refname = malloc(iref.name_len + 1);
344 			if (refname == NULL) {
345 				err = got_error_from_errno("malloc");
346 				goto done;
347 			}
348 			memcpy(refname, imsg.data + sizeof(iref),
349 			    iref.name_len);
350 			refname[iref.name_len] = '\0';
351 			err = send_ref(outfd, iref.id, refname,
352 			    !sent_capabilities, client_is_reading,
353 			    NULL, chattygot);
354 			free(refname);
355 			refname = NULL;
356 			if (err)
357 				goto done;
358 			sent_capabilities = 1;
359 			if (nrefs > 0)
360 				nrefs--;
361 			break;
362 		case GOTD_IMSG_SYMREF:
363 			if (!have_nrefs || nrefs == 0) {
364 				err = got_error(GOT_ERR_PRIVSEP_MSG);
365 				goto done;
366 			}
367 			if (datalen < sizeof(isymref)) {
368 				err = got_error(GOT_ERR_PRIVSEP_LEN);
369 				goto done;
370 			}
371 			memcpy(&isymref, imsg.data, sizeof(isymref));
372 			if (datalen != sizeof(isymref) + isymref.name_len +
373 			    isymref.target_len) {
374 				err = got_error(GOT_ERR_PRIVSEP_LEN);
375 				goto done;
376 			}
377 
378 			/*
379 			 * For now, we only announce one symbolic ref,
380 			 * as part of our capability advertisement.
381 			 */
382 			if (sent_capabilities || symrefstr != NULL ||
383 			    symrefname != NULL || symreftarget != NULL)
384 				break;
385 
386 			symrefname = malloc(isymref.name_len + 1);
387 			if (symrefname == NULL) {
388 				err = got_error_from_errno("malloc");
389 				goto done;
390 			}
391 			memcpy(symrefname, imsg.data + sizeof(isymref),
392 			    isymref.name_len);
393 			symrefname[isymref.name_len] = '\0';
394 
395 			symreftarget = malloc(isymref.target_len + 1);
396 			if (symreftarget == NULL) {
397 				err = got_error_from_errno("malloc");
398 				goto done;
399 			}
400 			memcpy(symreftarget,
401 			    imsg.data + sizeof(isymref) + isymref.name_len,
402 			    isymref.target_len);
403 			symreftarget[isymref.target_len] = '\0';
404 
405 			if (asprintf(&symrefstr, "%s:%s", symrefname,
406 			    symreftarget) == -1) {
407 				err = got_error_from_errno("asprintf");
408 				goto done;
409 			}
410 			err = send_ref(outfd, isymref.target_id, symrefname,
411 			    !sent_capabilities, client_is_reading, symrefstr,
412 			    chattygot);
413 			free(refname);
414 			refname = NULL;
415 			if (err)
416 				goto done;
417 			sent_capabilities = 1;
418 			if (nrefs > 0)
419 				nrefs--;
420 			break;
421 		default:
422 			err = got_error(GOT_ERR_PRIVSEP_MSG);
423 			break;
424 		}
425 
426 		imsg_free(&imsg);
427 	}
428 
429 	err = got_pkt_flushpkt(outfd, chattygot);
430 	if (err)
431 		goto done;
432 done:
433 	free(symrefstr);
434 	free(symrefname);
435 	free(symreftarget);
436 	return err;
437 }
438 
439 static const struct got_error *
440 parse_want_line(char **common_capabilities, uint8_t *id, char *buf, size_t len)
441 {
442 	const struct got_error *err;
443 	char *id_str = NULL, *client_capabilities = NULL;
444 
445 	err = got_gitproto_parse_want_line(&id_str,
446 	    &client_capabilities, buf, len);
447 	if (err)
448 		return err;
449 
450 	if (!got_parse_sha1_digest(id, id_str)) {
451 		err = got_error_msg(GOT_ERR_BAD_PACKET,
452 		    "want-line with bad object ID");
453 		goto done;
454 	}
455 
456 	if (client_capabilities) {
457 		err = got_gitproto_match_capabilities(common_capabilities,
458 		    NULL, client_capabilities, read_capabilities,
459 		    nitems(read_capabilities));
460 		if (err)
461 			goto done;
462 	}
463 done:
464 	free(id_str);
465 	free(client_capabilities);
466 	return err;
467 }
468 
469 static const struct got_error *
470 parse_have_line(uint8_t *id, char *buf, size_t len)
471 {
472 	const struct got_error *err;
473 	char *id_str = NULL;
474 
475 	err = got_gitproto_parse_have_line(&id_str, buf, len);
476 	if (err)
477 		return err;
478 
479 	if (!got_parse_sha1_digest(id, id_str)) {
480 		err = got_error_msg(GOT_ERR_BAD_PACKET,
481 		    "have-line with bad object ID");
482 		goto done;
483 	}
484 done:
485 	free(id_str);
486 	return err;
487 }
488 
489 static const struct got_error *
490 send_capability(struct got_capability *capa, struct imsgbuf *ibuf)
491 {
492 	const struct got_error *err = NULL;
493 	struct gotd_imsg_capability icapa;
494 	size_t len;
495 	struct ibuf *wbuf;
496 
497 	memset(&icapa, 0, sizeof(icapa));
498 
499 	icapa.key_len = strlen(capa->key);
500 	len = sizeof(icapa) + icapa.key_len;
501 	if (capa->value) {
502 		icapa.value_len = strlen(capa->value);
503 		len += icapa.value_len;
504 	}
505 
506 	wbuf = imsg_create(ibuf, GOTD_IMSG_CAPABILITY, 0, 0, len);
507 	if (wbuf == NULL) {
508 		err = got_error_from_errno("imsg_create CAPABILITY");
509 		return err;
510 	}
511 
512 	if (imsg_add(wbuf, &icapa, sizeof(icapa)) == -1)
513 		return got_error_from_errno("imsg_add CAPABILITY");
514 	if (imsg_add(wbuf, capa->key, icapa.key_len) == -1)
515 		return got_error_from_errno("imsg_add CAPABILITY");
516 	if (capa->value) {
517 		if (imsg_add(wbuf, capa->value, icapa.value_len) == -1)
518 			return got_error_from_errno("imsg_add CAPABILITY");
519 	}
520 
521 	wbuf->fd = -1;
522 	imsg_close(ibuf, wbuf);
523 
524 	return NULL;
525 }
526 
527 static const struct got_error *
528 send_capabilities(int *use_sidebands, int *report_status,
529     char *capabilities_str, struct imsgbuf *ibuf)
530 {
531 	const struct got_error *err = NULL;
532 	struct gotd_imsg_capabilities icapas;
533 	struct got_capability *capa = NULL;
534 	size_t ncapa, i;
535 
536 	err = got_gitproto_split_capabilities_str(&capa, &ncapa,
537 	    capabilities_str);
538 	if (err)
539 		return err;
540 
541 	icapas.ncapabilities = ncapa;
542 	if (imsg_compose(ibuf, GOTD_IMSG_CAPABILITIES, 0, 0, -1,
543 	    &icapas, sizeof(icapas)) == -1) {
544 		err = got_error_from_errno("imsg_compose IMSG_CAPABILITIES");
545 		goto done;
546 	}
547 
548 	for (i = 0; i < ncapa; i++) {
549 		err = send_capability(&capa[i], ibuf);
550 		if (err)
551 			goto done;
552 		if (use_sidebands &&
553 		    strcmp(capa[i].key, GOT_CAPA_SIDE_BAND_64K) == 0)
554 			*use_sidebands = 1;
555 		if (report_status &&
556 		    strcmp(capa[i].key, GOT_CAPA_REPORT_STATUS) == 0)
557 			*report_status = 1;
558 	}
559 done:
560 	free(capa);
561 	return err;
562 }
563 
564 static const struct got_error *
565 forward_flushpkt(struct imsgbuf *ibuf)
566 {
567 	if (imsg_compose(ibuf, GOTD_IMSG_FLUSH, 0, 0, -1, NULL, 0) == -1)
568 		return got_error_from_errno("imsg_compose FLUSH");
569 
570 	return gotd_imsg_flush(ibuf);
571 }
572 
573 static const struct got_error *
574 recv_ack(struct imsg *imsg, uint8_t *expected_id)
575 {
576 	struct gotd_imsg_ack iack;
577 	size_t datalen;
578 
579 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
580 	if (datalen != sizeof(iack))
581 		return got_error(GOT_ERR_PRIVSEP_LEN);
582 
583 	memcpy(&iack, imsg->data, sizeof(iack));
584 	if (memcmp(iack.object_id, expected_id, SHA1_DIGEST_LENGTH) != 0)
585 		return got_error(GOT_ERR_BAD_OBJ_ID);
586 
587 	return NULL;
588 }
589 
590 static const struct got_error *
591 recv_nak(struct imsg *imsg, uint8_t *expected_id)
592 {
593 	struct gotd_imsg_ack inak;
594 	size_t datalen;
595 
596 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
597 	if (datalen != sizeof(inak))
598 		return got_error(GOT_ERR_PRIVSEP_LEN);
599 
600 	memcpy(&inak, imsg->data, sizeof(inak));
601 	if (memcmp(inak.object_id, expected_id, SHA1_DIGEST_LENGTH) != 0)
602 		return got_error(GOT_ERR_BAD_OBJ_ID);
603 
604 	return NULL;
605 }
606 
607 
608 static const struct got_error *
609 recv_want(int *use_sidebands, int outfd, struct imsgbuf *ibuf,
610     char *buf, size_t len, int expect_capabilities, int chattygot)
611 {
612 	const struct got_error *err;
613 	struct gotd_imsg_want iwant;
614 	char *capabilities_str;
615 	int done = 0;
616 	struct imsg imsg;
617 
618 	memset(&iwant, 0, sizeof(iwant));
619 	memset(&imsg, 0, sizeof(imsg));
620 
621 	err = parse_want_line(&capabilities_str, iwant.object_id, buf, len);
622 	if (err)
623 		return err;
624 
625 	if (capabilities_str) {
626 		if (!expect_capabilities) {
627 			err = got_error_msg(GOT_ERR_BAD_PACKET,
628 			    "unexpected capability announcement received");
629 			goto done;
630 		}
631 		err = send_capabilities(use_sidebands, NULL, capabilities_str,
632 		    ibuf);
633 		if (err)
634 			goto done;
635 
636 	}
637 
638 	if (imsg_compose(ibuf, GOTD_IMSG_WANT, 0, 0, -1,
639 	    &iwant, sizeof(iwant)) == -1) {
640 		err = got_error_from_errno("imsg_compose WANT");
641 		goto done;
642 	}
643 
644 	err = gotd_imsg_flush(ibuf);
645 	if (err)
646 		goto done;
647 
648 	/*
649 	 * Wait for an ACK, or an error in case the desired object
650 	 * does not exist.
651 	 */
652 	while (!done && err == NULL) {
653 		err = gotd_imsg_poll_recv(&imsg, ibuf, 0);
654 		if (err)
655 			break;
656 		switch (imsg.hdr.type) {
657 		case GOTD_IMSG_ERROR:
658 			err = gotd_imsg_recv_error(NULL, &imsg);
659 			break;
660 		case GOTD_IMSG_ACK:
661 			err = recv_ack(&imsg, iwant.object_id);
662 			if (err)
663 				break;
664 			done = 1;
665 			break;
666 		default:
667 			err = got_error(GOT_ERR_PRIVSEP_MSG);
668 			break;
669 		}
670 
671 		imsg_free(&imsg);
672 	}
673 done:
674 	free(capabilities_str);
675 	return err;
676 }
677 
678 static const struct got_error *
679 send_ack(int outfd, uint8_t *id, int chattygot)
680 {
681 	char hex[SHA1_DIGEST_STRING_LENGTH];
682 	char buf[GOT_PKT_MAX];
683 	int len;
684 
685 	if (got_sha1_digest_to_str(id, hex, sizeof(hex)) == NULL)
686 		return got_error(GOT_ERR_BAD_OBJ_ID);
687 
688 	len = snprintf(buf, sizeof(buf), "ACK %s\n", hex);
689 	if (len >= sizeof(buf))
690 		return got_error(GOT_ERR_NO_SPACE);
691 
692 	return got_pkt_writepkt(outfd, buf, len, chattygot);
693 }
694 
695 static const struct got_error *
696 send_nak(int outfd, int chattygot)
697 {
698 	char buf[5];
699 	int len;
700 
701 	len = snprintf(buf, sizeof(buf), "NAK\n");
702 	if (len >= sizeof(buf))
703 		return got_error(GOT_ERR_NO_SPACE);
704 
705 	return got_pkt_writepkt(outfd, buf, len, chattygot);
706 }
707 
708 static const struct got_error *
709 recv_have(int *have_ack, int outfd, struct imsgbuf *ibuf, char *buf,
710     size_t len, int chattygot)
711 {
712 	const struct got_error *err;
713 	struct gotd_imsg_have ihave;
714 	int done = 0;
715 	struct imsg imsg;
716 
717 	memset(&ihave, 0, sizeof(ihave));
718 	memset(&imsg, 0, sizeof(imsg));
719 
720 	err = parse_have_line(ihave.object_id, buf, len);
721 	if (err)
722 		return err;
723 
724 	if (imsg_compose(ibuf, GOTD_IMSG_HAVE, 0, 0, -1,
725 	    &ihave, sizeof(ihave)) == -1)
726 		return got_error_from_errno("imsg_compose HAVE");
727 
728 	err = gotd_imsg_flush(ibuf);
729 	if (err)
730 		return err;
731 
732 	/*
733 	 * Wait for an ACK or a NAK, indicating whether a common
734 	 * commit object has been found.
735 	 */
736 	while (!done && err == NULL) {
737 		err = gotd_imsg_poll_recv(&imsg, ibuf, 0);
738 		if (err)
739 			return err;
740 		switch (imsg.hdr.type) {
741 		case GOTD_IMSG_ERROR:
742 			err = gotd_imsg_recv_error(NULL, &imsg);
743 			break;
744 		case GOTD_IMSG_ACK:
745 			err = recv_ack(&imsg, ihave.object_id);
746 			if (err)
747 				break;
748 			if (!*have_ack) {
749 				err = send_ack(outfd, ihave.object_id,
750 				    chattygot);
751 				if (err)
752 					return err;
753 				*have_ack = 1;
754 			}
755 			done = 1;
756 			break;
757 		case GOTD_IMSG_NAK:
758 			err = recv_nak(&imsg, ihave.object_id);
759 			if (err)
760 				break;
761 			done = 1;
762 			break;
763 		default:
764 			err = got_error(GOT_ERR_PRIVSEP_MSG);
765 			break;
766 		}
767 
768 		imsg_free(&imsg);
769 	}
770 
771 	return err;
772 }
773 
774 static const struct got_error *
775 recv_done(int *packfd, int outfd, struct imsgbuf *ibuf, int chattygot)
776 {
777 	const struct got_error *err;
778 	struct imsg imsg;
779 
780 	*packfd = -1;
781 
782 	if (imsg_compose(ibuf, GOTD_IMSG_DONE, 0, 0, -1, NULL, 0) == -1)
783 		return got_error_from_errno("imsg_compose DONE");
784 
785 	err = gotd_imsg_flush(ibuf);
786 	if (err)
787 		return err;
788 
789 	while (*packfd == -1 && err == NULL) {
790 		err = gotd_imsg_poll_recv(&imsg, ibuf, 0);
791 		if (err)
792 			break;
793 
794 		switch (imsg.hdr.type) {
795 		case GOTD_IMSG_ERROR:
796 			err = gotd_imsg_recv_error(NULL, &imsg);
797 			break;
798 		case GOTD_IMSG_PACKFILE_PIPE:
799 			if (imsg.fd != -1)
800 				*packfd = imsg.fd;
801 			else
802 				err = got_error(GOT_ERR_PRIVSEP_NO_FD);
803 			break;
804 		default:
805 			err = got_error(GOT_ERR_PRIVSEP_MSG);
806 			break;
807 		}
808 
809 		imsg_free(&imsg);
810 	}
811 
812 	return err;
813 }
814 
815 static const struct got_error *
816 relay_progress_reports(struct imsgbuf *ibuf, int outfd, int chattygot)
817 {
818 	const struct got_error *err = NULL;
819 	int pack_starting = 0;
820 	struct gotd_imsg_packfile_progress iprog;
821 	char buf[GOT_PKT_MAX];
822 	struct imsg imsg;
823 	size_t datalen;
824 	int p_deltify = 0, n;
825 	const char *eol = "\r";
826 
827 	memset(&imsg, 0, sizeof(imsg));
828 
829 	while (!pack_starting && err == NULL) {
830 		err = gotd_imsg_poll_recv(&imsg, ibuf, 0);
831 		if (err)
832 			break;
833 
834 		datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
835 		switch (imsg.hdr.type) {
836 		case GOTD_IMSG_ERROR:
837 			err = gotd_imsg_recv_error(NULL, &imsg);
838 			break;
839 		case GOTD_IMSG_PACKFILE_READY:
840 			eol = "\n";
841 			pack_starting = 1;
842 			/* fallthrough */
843 		case GOTD_IMSG_PACKFILE_PROGRESS:
844 			if (datalen != sizeof(iprog)) {
845 				err = got_error(GOT_ERR_PRIVSEP_LEN);
846 				break;
847 			}
848 			memcpy(&iprog, imsg.data, sizeof(iprog));
849 			if (iprog.nobj_total > 0) {
850 				p_deltify = (iprog.nobj_deltify * 100) /
851 				    iprog.nobj_total;
852 			}
853 			buf[0] = GOT_SIDEBAND_PROGRESS_INFO;
854 			n = snprintf(&buf[1], sizeof(buf) - 1,
855 			    "%d commits colored, "
856 			    "%d objects found, "
857 			    "deltify %d%%%s",
858 			    iprog.ncolored,
859 			    iprog.nfound,
860 			    p_deltify, eol);
861 			if (n >= sizeof(buf) - 1)
862 				break;
863 			err = got_pkt_writepkt(outfd, buf, 1 + n, chattygot);
864 			break;
865 		default:
866 			err = got_error(GOT_ERR_PRIVSEP_MSG);
867 			break;
868 		}
869 
870 		imsg_free(&imsg);
871 	}
872 
873 	return err;
874 }
875 
876 static const struct got_error *
877 serve_read(int infd, int outfd, int gotd_sock, const char *repo_path,
878     int chattygot)
879 {
880 	const struct got_error *err = NULL;
881 	char buf[GOT_PKT_MAX];
882 	struct imsgbuf ibuf;
883 	enum protostate {
884 		STATE_EXPECT_WANT,
885 		STATE_EXPECT_MORE_WANT,
886 		STATE_EXPECT_HAVE,
887 		STATE_EXPECT_DONE,
888 		STATE_DONE,
889 	};
890 	enum protostate curstate = STATE_EXPECT_WANT;
891 	int have_ack = 0, use_sidebands = 0, seen_have = 0;
892 	int packfd = -1;
893 	size_t pack_chunksize;
894 
895 	imsg_init(&ibuf, gotd_sock);
896 
897 	err = announce_refs(outfd, &ibuf, 1, repo_path, chattygot);
898 	if (err)
899 		goto done;
900 
901 	while (curstate != STATE_DONE) {
902 		int n;
903 		buf[0] = '\0';
904 		err = got_pkt_readpkt(&n, infd, buf, sizeof(buf), chattygot);
905 		if (err)
906 			break;
907 		if (n == 0) {
908 			if (curstate != STATE_EXPECT_MORE_WANT &&
909 			    curstate != STATE_EXPECT_HAVE) {
910 				err = got_error_msg(GOT_ERR_BAD_PACKET,
911 				    "unexpected flush packet received");
912 				goto done;
913 			}
914 			err = forward_flushpkt(&ibuf);
915 			if (err)
916 				goto done;
917 			if (curstate == STATE_EXPECT_HAVE && !have_ack) {
918 				err = send_nak(outfd, chattygot);
919 				if (err)
920 					goto done;
921 			}
922 			if (curstate == STATE_EXPECT_MORE_WANT)
923 				curstate = STATE_EXPECT_HAVE;
924 			else
925 				curstate = STATE_EXPECT_DONE;
926 		} else if (n >= 5 && strncmp(buf, "want ", 5) == 0) {
927 			if (curstate != STATE_EXPECT_WANT &&
928 			    curstate != STATE_EXPECT_MORE_WANT) {
929 				err = got_error_msg(GOT_ERR_BAD_PACKET,
930 				    "unexpected 'want' packet");
931 				goto done;
932 			}
933 			err = recv_want(&use_sidebands, outfd, &ibuf, buf, n,
934 			    curstate == STATE_EXPECT_WANT ? 1 : 0, chattygot);
935 			if (err)
936 				goto done;
937 			if (curstate == STATE_EXPECT_WANT)
938 				curstate = STATE_EXPECT_MORE_WANT;
939 		} else if (n >= 5 && strncmp(buf, "have ", 5) == 0) {
940 			if (curstate != STATE_EXPECT_HAVE) {
941 				err = got_error_msg(GOT_ERR_BAD_PACKET,
942 				    "unexpected 'have' packet");
943 				goto done;
944 			}
945 			err = recv_have(&have_ack, outfd, &ibuf, buf, n,
946 			    chattygot);
947 			if (err)
948 				goto done;
949 			seen_have = 1;
950 		} else if (n == 5 && strncmp(buf, "done\n", 5) == 0) {
951 			if (curstate != STATE_EXPECT_HAVE &&
952 			    curstate != STATE_EXPECT_DONE) {
953 				err = got_error_msg(GOT_ERR_BAD_PACKET,
954 				    "unexpected 'done' packet");
955 				goto done;
956 			}
957 			err = recv_done(&packfd, outfd, &ibuf, chattygot);
958 			if (err)
959 				goto done;
960 			curstate = STATE_DONE;
961 			break;
962 		} else {
963 			err = got_error(GOT_ERR_BAD_PACKET);
964 			goto done;
965 		}
966 	}
967 
968 	if (!seen_have) {
969 		err = send_nak(outfd, chattygot);
970 		if (err)
971 			goto done;
972 	}
973 
974 	if (use_sidebands) {
975 		err = relay_progress_reports(&ibuf, outfd, chattygot);
976 		if (err)
977 			goto done;
978 		pack_chunksize = GOT_SIDEBAND_64K_PACKFILE_DATA_MAX;
979 	} else
980 		pack_chunksize = sizeof(buf);
981 
982 	for (;;) {
983 		ssize_t r;
984 
985 		r = read(packfd, use_sidebands ? &buf[1] : buf,
986 		    pack_chunksize);
987 		if (r == -1) {
988 			err = got_error_from_errno("read");
989 			break;
990 		} else if (r == 0) {
991 			err = got_pkt_flushpkt(outfd, chattygot);
992 			break;
993 		}
994 
995 		if (use_sidebands) {
996 			buf[0] = GOT_SIDEBAND_PACKFILE_DATA;
997 			err = got_pkt_writepkt(outfd, buf, 1 + r, chattygot);
998 			if (err)
999 				break;
1000 		} else {
1001 			err = got_poll_write_full(outfd, buf, r);
1002 			if (err) {
1003 				if (err->code == GOT_ERR_EOF)
1004 					err = NULL;
1005 				break;
1006 			}
1007 		}
1008 	}
1009 done:
1010 	imsg_clear(&ibuf);
1011 	if (packfd != -1 && close(packfd) == -1 && err == NULL)
1012 		err = got_error_from_errno("close");
1013 	if (err)
1014 		echo_error(err, outfd, chattygot);
1015 	return err;
1016 }
1017 
1018 static const struct got_error *
1019 parse_ref_update_line(char **common_capabilities, char **refname,
1020     uint8_t *old_id, uint8_t *new_id, char *buf, size_t len)
1021 {
1022 	const struct got_error *err;
1023 	char *old_id_str = NULL, *new_id_str = NULL;
1024 	char *client_capabilities = NULL;
1025 
1026 	*refname = NULL;
1027 
1028 	err = got_gitproto_parse_ref_update_line(&old_id_str, &new_id_str,
1029 	    refname, &client_capabilities, buf, len);
1030 	if (err)
1031 		return err;
1032 
1033 	if (!got_parse_sha1_digest(old_id, old_id_str) ||
1034 	    !got_parse_sha1_digest(new_id, new_id_str)) {
1035 		err = got_error_msg(GOT_ERR_BAD_PACKET,
1036 		    "ref-update with bad object ID");
1037 		goto done;
1038 	}
1039 	if (!got_ref_name_is_valid(*refname)) {
1040 		err = got_error_msg(GOT_ERR_BAD_PACKET,
1041 		    "ref-update with bad reference name");
1042 		goto done;
1043 	}
1044 
1045 	if (client_capabilities) {
1046 		err = got_gitproto_match_capabilities(common_capabilities,
1047 		    NULL, client_capabilities, write_capabilities,
1048 		    nitems(write_capabilities));
1049 		if (err)
1050 			goto done;
1051 	}
1052 done:
1053 	free(old_id_str);
1054 	free(new_id_str);
1055 	free(client_capabilities);
1056 	if (err) {
1057 		free(*refname);
1058 		*refname = NULL;
1059 	}
1060 	return err;
1061 }
1062 
1063 static const struct got_error *
1064 recv_ref_update(int *report_status, int outfd, struct imsgbuf *ibuf,
1065     char *buf, size_t len, int expect_capabilities, int chattygot)
1066 {
1067 	const struct got_error *err;
1068 	struct gotd_imsg_ref_update iref;
1069 	struct ibuf *wbuf;
1070 	char *capabilities_str = NULL, *refname = NULL;
1071 	int done = 0;
1072 	struct imsg imsg;
1073 
1074 	memset(&iref, 0, sizeof(iref));
1075 	memset(&imsg, 0, sizeof(imsg));
1076 
1077 	err = parse_ref_update_line(&capabilities_str, &refname,
1078 	    iref.old_id, iref.new_id, buf, len);
1079 	if (err)
1080 		return err;
1081 
1082 	if (capabilities_str) {
1083 		if (!expect_capabilities) {
1084 			err = got_error_msg(GOT_ERR_BAD_PACKET,
1085 			    "unexpected capability announcement received");
1086 			goto done;
1087 		}
1088 		err = send_capabilities(NULL, report_status, capabilities_str,
1089 		    ibuf);
1090 		if (err)
1091 			goto done;
1092 	}
1093 
1094 	iref.name_len = strlen(refname);
1095 	len = sizeof(iref) + iref.name_len;
1096 	wbuf = imsg_create(ibuf, GOTD_IMSG_REF_UPDATE, 0, 0, len);
1097 	if (wbuf == NULL) {
1098 		err = got_error_from_errno("imsg_create REF_UPDATE");
1099 		goto done;
1100 	}
1101 
1102 	if (imsg_add(wbuf, &iref, sizeof(iref)) == -1)
1103 		return got_error_from_errno("imsg_add REF_UPDATE");
1104 	if (imsg_add(wbuf, refname, iref.name_len) == -1)
1105 		return got_error_from_errno("imsg_add REF_UPDATE");
1106 	wbuf->fd = -1;
1107 	imsg_close(ibuf, wbuf);
1108 
1109 	err = gotd_imsg_flush(ibuf);
1110 	if (err)
1111 		goto done;
1112 
1113 	/* Wait for ACK or an error. */
1114 	while (!done && err == NULL) {
1115 		err = gotd_imsg_poll_recv(&imsg, ibuf, 0);
1116 		if (err)
1117 			break;
1118 		switch (imsg.hdr.type) {
1119 		case GOTD_IMSG_ERROR:
1120 			err = gotd_imsg_recv_error(NULL, &imsg);
1121 			break;
1122 		case GOTD_IMSG_ACK:
1123 			err = recv_ack(&imsg, iref.new_id);
1124 			if (err)
1125 				break;
1126 			done = 1;
1127 			break;
1128 		default:
1129 			err = got_error(GOT_ERR_PRIVSEP_MSG);
1130 			break;
1131 		}
1132 
1133 		imsg_free(&imsg);
1134 	}
1135 done:
1136 	free(capabilities_str);
1137 	free(refname);
1138 	return err;
1139 }
1140 
1141 static const struct got_error *
1142 recv_packfile(struct imsg *imsg, int infd)
1143 {
1144 	const struct got_error *err = NULL;
1145 	size_t datalen;
1146 	int packfd;
1147 	char buf[GOT_PKT_MAX];
1148 	int pack_done = 0;
1149 
1150 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
1151 	if (datalen != 0)
1152 		return got_error(GOT_ERR_PRIVSEP_MSG);
1153 
1154 	if (imsg->fd == -1)
1155 		return got_error(GOT_ERR_PRIVSEP_NO_FD);
1156 	
1157 	packfd = imsg->fd;
1158 	while (!pack_done) {
1159 		ssize_t r = 0;
1160 
1161 		err = got_poll_fd(infd, POLLIN, 1);
1162 		if (err) {
1163 			if (err->code != GOT_ERR_TIMEOUT)
1164 				break;
1165 			err = NULL;
1166 		} else {
1167 			r = read(infd, buf, sizeof(buf));
1168 			if (r == -1) {
1169 				err = got_error_from_errno("read");
1170 				break;
1171 			}
1172 			if (r == 0) {
1173 				/*
1174 				 * Git clients hang up their side of the
1175 				 * connection after sending the pack file.
1176 				 */
1177 				err = NULL;
1178 				pack_done = 1;
1179 				break;
1180 			}
1181 		}
1182 
1183 		if (r == 0) {
1184 			/* Detect gotd(8) closing the pack pipe when done. */
1185 			err = got_poll_fd(packfd, POLLOUT, 1);
1186 			if (err) {
1187 				if (err->code != GOT_ERR_EOF)
1188 					break;
1189 				err = NULL;
1190 				pack_done = 1;
1191 			}
1192 		} else {
1193 			/* Write pack data and/or detect pipe being closed. */
1194 			err = got_poll_write_full(packfd, buf, r);
1195 			if (err) {
1196 				if (err->code == GOT_ERR_EOF)
1197 					err = NULL;
1198 				break;
1199 			}
1200 		}
1201 	}
1202 
1203 	close(packfd);
1204 	return err;
1205 }
1206 
1207 static const struct got_error *
1208 report_unpack_status(struct imsg *imsg, int outfd, int chattygot)
1209 {
1210 	const struct got_error *err = NULL;
1211 	struct gotd_imsg_packfile_status istatus;
1212 	char buf[GOT_PKT_MAX];
1213 	size_t datalen, len;
1214 	char *reason = NULL;
1215 
1216 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
1217 	if (datalen < sizeof(istatus))
1218 		return got_error(GOT_ERR_PRIVSEP_LEN);
1219 	memcpy(&istatus, imsg->data, sizeof(istatus));
1220 	if (datalen != sizeof(istatus) + istatus.reason_len)
1221 		return got_error(GOT_ERR_PRIVSEP_LEN);
1222 
1223 	reason = malloc(istatus.reason_len + 1);
1224 	if (reason == NULL) {
1225 		err = got_error_from_errno("malloc");
1226 		goto done;
1227 	}
1228 	memcpy(reason, imsg->data + sizeof(istatus), istatus.reason_len);
1229 	reason[istatus.reason_len] = '\0';
1230 
1231 	if (err == NULL)
1232 		len = snprintf(buf, sizeof(buf), "unpack ok\n");
1233 	else
1234 		len = snprintf(buf, sizeof(buf), "unpack %s\n", reason);
1235 	if (len >= sizeof(buf)) {
1236 		err = got_error(GOT_ERR_NO_SPACE);
1237 		goto done;
1238 	}
1239 
1240 	err = got_pkt_writepkt(outfd, buf, len, chattygot);
1241 done:
1242 	free(reason);
1243 	return err;
1244 }
1245 
1246 static const struct got_error *
1247 recv_ref_update_ok(struct imsg *imsg, int outfd, int chattygot)
1248 {
1249 	const struct got_error *err = NULL;
1250 	struct gotd_imsg_ref_update_ok iok;
1251 	size_t datalen, len;
1252 	char buf[GOT_PKT_MAX];
1253 	char *refname = NULL;
1254 
1255 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
1256 	if (datalen < sizeof(iok))
1257 		return got_error(GOT_ERR_PRIVSEP_LEN);
1258 	memcpy(&iok, imsg->data, sizeof(iok));
1259 	if (datalen != sizeof(iok) + iok.name_len)
1260 		return got_error(GOT_ERR_PRIVSEP_LEN);
1261 
1262 	memcpy(&iok, imsg->data, sizeof(iok));
1263 
1264 	refname = malloc(iok.name_len + 1);
1265 	if (refname == NULL)
1266 		return got_error_from_errno("malloc");
1267 	memcpy(refname, imsg->data + sizeof(iok), iok.name_len);
1268 	refname[iok.name_len] = '\0';
1269 
1270 	len = snprintf(buf, sizeof(buf), "ok %s\n", refname);
1271 	if (len >= sizeof(buf)) {
1272 		err = got_error(GOT_ERR_NO_SPACE);
1273 		goto done;
1274 	}
1275 
1276 	err = got_pkt_writepkt(outfd, buf, len, chattygot);
1277 done:
1278 	free(refname);
1279 	return err;
1280 }
1281 
1282 static const struct got_error *
1283 recv_ref_update_ng(struct imsg *imsg, int outfd, int chattygot)
1284 {
1285 	const struct got_error *err = NULL;
1286 	struct gotd_imsg_ref_update_ng ing;
1287 	size_t datalen, len;
1288 	char buf[GOT_PKT_MAX];
1289 	char *refname = NULL, *reason = NULL;
1290 
1291 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
1292 	if (datalen < sizeof(ing))
1293 		return got_error(GOT_ERR_PRIVSEP_LEN);
1294 	memcpy(&ing, imsg->data, sizeof(ing));
1295 	if (datalen != sizeof(ing) + ing.name_len + ing.reason_len)
1296 		return got_error(GOT_ERR_PRIVSEP_LEN);
1297 
1298 	memcpy(&ing, imsg->data, sizeof(ing));
1299 
1300 	refname = malloc(ing.name_len + 1);
1301 	if (refname == NULL)
1302 		return got_error_from_errno("malloc");
1303 	memcpy(refname, imsg->data + sizeof(ing), ing.name_len);
1304 	refname[ing.name_len] = '\0';
1305 
1306 	reason = malloc(ing.reason_len + 1);
1307 	if (reason == NULL) {
1308 		err = got_error_from_errno("malloc");
1309 		goto done;
1310 	}
1311 	memcpy(refname, imsg->data + sizeof(ing) + ing.name_len,
1312 	    ing.reason_len);
1313 	refname[ing.reason_len] = '\0';
1314 
1315 	len = snprintf(buf, sizeof(buf), "ng %s %s\n", refname, reason);
1316 	if (len >= sizeof(buf)) {
1317 		err = got_error(GOT_ERR_NO_SPACE);
1318 		goto done;
1319 	}
1320 
1321 	err = got_pkt_writepkt(outfd, buf, len, chattygot);
1322 done:
1323 	free(refname);
1324 	free(reason);
1325 	return err;
1326 }
1327 
1328 static const struct got_error *
1329 serve_write(int infd, int outfd, int gotd_sock, const char *repo_path,
1330     int chattygot)
1331 {
1332 	const struct got_error *err = NULL;
1333 	char buf[GOT_PKT_MAX];
1334 	struct imsgbuf ibuf;
1335 	enum protostate {
1336 		STATE_EXPECT_REF_UPDATE,
1337 		STATE_EXPECT_MORE_REF_UPDATES,
1338 		STATE_EXPECT_PACKFILE,
1339 		STATE_PACKFILE_RECEIVED,
1340 		STATE_REFS_UPDATED,
1341 	};
1342 	enum protostate curstate = STATE_EXPECT_REF_UPDATE;
1343 	struct imsg imsg;
1344 	int report_status = 0;
1345 
1346 	imsg_init(&ibuf, gotd_sock);
1347 	memset(&imsg, 0, sizeof(imsg));
1348 
1349 	err = announce_refs(outfd, &ibuf, 0, repo_path, chattygot);
1350 	if (err)
1351 		goto done;
1352 
1353 	while (curstate != STATE_EXPECT_PACKFILE) {
1354 		int n;
1355 		buf[0] = '\0';
1356 		err = got_pkt_readpkt(&n, infd, buf, sizeof(buf), chattygot);
1357 		if (err)
1358 			break;
1359 		if (n == 0) {
1360 			if (curstate != STATE_EXPECT_MORE_REF_UPDATES) {
1361 				err = got_error_msg(GOT_ERR_BAD_PACKET,
1362 				    "unexpected flush packet received");
1363 				goto done;
1364 			}
1365 			err = forward_flushpkt(&ibuf);
1366 			if (err)
1367 				goto done;
1368 			curstate = STATE_EXPECT_PACKFILE;
1369 		} else if (n >= (SHA1_DIGEST_STRING_LENGTH * 2) + 2) {
1370 			if (curstate != STATE_EXPECT_REF_UPDATE &&
1371 			    curstate != STATE_EXPECT_MORE_REF_UPDATES) {
1372 				err = got_error_msg(GOT_ERR_BAD_PACKET,
1373 				    "unexpected ref-update packet");
1374 				goto done;
1375 			}
1376 			if (curstate == STATE_EXPECT_REF_UPDATE) {
1377 				err = recv_ref_update(&report_status,
1378 				    outfd, &ibuf, buf, n, 1, chattygot);
1379 			} else {
1380 				err = recv_ref_update(NULL, outfd, &ibuf,
1381 				    buf, n, 0, chattygot);
1382 			}
1383 			if (err)
1384 				goto done;
1385 			curstate = STATE_EXPECT_MORE_REF_UPDATES;
1386 		} else {
1387 			err = got_error(GOT_ERR_BAD_PACKET);
1388 			goto done;
1389 		}
1390 	}
1391 
1392 	while (curstate != STATE_PACKFILE_RECEIVED) {
1393 		err = gotd_imsg_poll_recv(&imsg, &ibuf, 0);
1394 		if (err)
1395 			goto done;
1396 		switch (imsg.hdr.type) {
1397 		case GOTD_IMSG_ERROR:
1398 			err = gotd_imsg_recv_error(NULL, &imsg);
1399 			goto done;
1400 		case GOTD_IMSG_PACKFILE_PIPE:
1401 			err = recv_packfile(&imsg, infd);
1402 			if (err) {
1403 				if (err->code != GOT_ERR_EOF)
1404 					goto done;
1405 				/*
1406 				 * EOF is reported when the client hangs up,
1407 				 * which can happen with Git clients.
1408 				 * The socket should stay half-open so we
1409 				 * can still send our reports if requested.
1410 				 */
1411 				err = NULL;
1412 			}
1413 			curstate = STATE_PACKFILE_RECEIVED;
1414 			break;
1415 		default:
1416 			err = got_error(GOT_ERR_PRIVSEP_MSG);
1417 			break;
1418 		}
1419 
1420 		imsg_free(&imsg);
1421 		if (err)
1422 			goto done;
1423 	}
1424 
1425 	while (curstate != STATE_REFS_UPDATED && err == NULL) {
1426 		err = gotd_imsg_poll_recv(&imsg, &ibuf, 0);
1427 		if (err)
1428 			break;
1429 		switch (imsg.hdr.type) {
1430 		case GOTD_IMSG_ERROR:
1431 			err = gotd_imsg_recv_error(NULL, &imsg);
1432 			break;
1433 		case GOTD_IMSG_PACKFILE_STATUS:
1434 			if (!report_status)
1435 				break;
1436 			err = report_unpack_status(&imsg, outfd, chattygot);
1437 			break;
1438 		case GOTD_IMSG_REF_UPDATE_OK:
1439 			if (!report_status)
1440 				break;
1441 			err = recv_ref_update_ok(&imsg, outfd, chattygot);
1442 			break;
1443 		case GOTD_IMSG_REF_UPDATE_NG:
1444 			if (!report_status)
1445 				break;
1446 			err = recv_ref_update_ng(&imsg, outfd, chattygot);
1447 			break;
1448 		case GOTD_IMSG_REFS_UPDATED:
1449 			curstate = STATE_REFS_UPDATED;
1450 			err = got_pkt_flushpkt(outfd, chattygot);
1451 			break;
1452 		default:
1453 			err = got_error(GOT_ERR_PRIVSEP_MSG);
1454 			break;
1455 		}
1456 
1457 		imsg_free(&imsg);
1458 	}
1459 done:
1460 	imsg_clear(&ibuf);
1461 	if (err)
1462 		echo_error(err, outfd, chattygot);
1463 	return err;
1464 }
1465 
1466 const struct got_error *
1467 got_serve(int infd, int outfd, const char *gitcmd, int gotd_sock, int chattygot)
1468 {
1469 	const struct got_error *err = NULL;
1470 	char *command = NULL, *repo_path = NULL;
1471 
1472 	err = parse_command(&command, &repo_path, gitcmd);
1473 	if (err)
1474 		return err;
1475 
1476 	if (strcmp(command, GOT_SERVE_CMD_FETCH) == 0)
1477 		err = serve_read(infd, outfd, gotd_sock, repo_path, chattygot);
1478 	else if (strcmp(command, GOT_SERVE_CMD_SEND) == 0)
1479 		err = serve_write(infd, outfd, gotd_sock, repo_path, chattygot);
1480 	else
1481 		err = got_error(GOT_ERR_BAD_PACKET);
1482 
1483 	free(command);
1484 	free(repo_path);
1485 	return err;
1486 }