1 /*
2  * Copyright (c) 2019 Ori Bernstein <ori@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 #include <sys/time.h>
21 #include <sys/stat.h>
22 
23 #include <stdint.h>
24 #include <errno.h>
25 #include <imsg.h>
26 #include <limits.h>
27 #include <signal.h>
28 #include <stdio.h>
29 #include <stdlib.h>
30 #include <string.h>
31 #include <ctype.h>
32 #include <sha1.h>
33 #include <fcntl.h>
34 #include <unistd.h>
35 #include <zlib.h>
36 #include <err.h>
37 
38 #include "got_error.h"
39 #include "got_object.h"
40 #include "got_path.h"
41 #include "got_version.h"
42 #include "got_fetch.h"
43 #include "got_reference.h"
44 
45 #include "got_lib_sha1.h"
46 #include "got_lib_delta.h"
47 #include "got_lib_object.h"
48 #include "got_lib_object_parse.h"
49 #include "got_lib_privsep.h"
50 #include "got_lib_pack.h"
51 #include "got_lib_pkt.h"
52 #include "got_lib_gitproto.h"
53 #include "got_lib_ratelimit.h"
54 
55 #ifndef MIN
56 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
57 #endif
58 
59 #ifndef nitems
60 #define nitems(_a)	(sizeof((_a)) / sizeof((_a)[0]))
61 #endif
62 
63 struct got_object *indexed;
64 static int chattygot;
65 
66 static const struct got_capability got_capabilities[] = {
67 	{ GOT_CAPA_AGENT, "got/" GOT_VERSION_STR },
68 	{ GOT_CAPA_OFS_DELTA, NULL },
69 	{ GOT_CAPA_SIDE_BAND_64K, NULL },
70 };
71 
72 static void
73 match_remote_ref(struct got_pathlist_head *have_refs,
74     struct got_object_id *my_id, const char *refname)
75 {
76 	struct got_pathlist_entry *pe;
77 
78 	/* XXX zero-hash signifies we don't have this ref;
79 	 * we should use a flag instead */
80 	memset(my_id, 0, sizeof(*my_id));
81 
82 	TAILQ_FOREACH(pe, have_refs, entry) {
83 		struct got_object_id *id = pe->data;
84 		if (strcmp(pe->path, refname) == 0) {
85 			memcpy(my_id, id, sizeof(*my_id));
86 			break;
87 		}
88 	}
89 }
90 
91 static int
92 match_branch(const char *branch, const char *wanted_branch)
93 {
94 	if (strncmp(branch, "refs/heads/", 11) != 0)
95 		return 0;
96 
97 	if (strncmp(wanted_branch, "refs/heads/", 11) == 0)
98 		wanted_branch += 11;
99 
100 	return (strcmp(branch + 11, wanted_branch) == 0);
101 }
102 
103 static int
104 match_wanted_ref(const char *refname, const char *wanted_ref)
105 {
106 	if (strncmp(refname, "refs/", 5) != 0)
107 		return 0;
108 	refname += 5;
109 
110 	/*
111 	 * Prevent fetching of references that won't make any
112 	 * sense outside of the remote repository's context.
113 	 */
114 	if (strncmp(refname, "got/", 4) == 0)
115 		return 0;
116 	if (strncmp(refname, "remotes/", 8) == 0)
117 		return 0;
118 
119 	if (strncmp(wanted_ref, "refs/", 5) == 0)
120 		wanted_ref += 5;
121 
122 	/* Allow prefix match. */
123 	if (got_path_is_child(refname, wanted_ref, strlen(wanted_ref)))
124 		return 1;
125 
126 	/* Allow exact match. */
127 	return (strcmp(refname, wanted_ref) == 0);
128 }
129 
130 static const struct got_error *
131 send_fetch_server_progress(struct imsgbuf *ibuf, const char *msg, size_t msglen)
132 {
133 	if (msglen > MAX_IMSGSIZE - IMSG_HEADER_SIZE)
134 		return got_error(GOT_ERR_NO_SPACE);
135 
136 	if (msglen == 0)
137 		return NULL;
138 
139 	if (imsg_compose(ibuf, GOT_IMSG_FETCH_SERVER_PROGRESS, 0, 0, -1,
140 	    msg, msglen) == -1)
141 		return got_error_from_errno(
142 		    "imsg_compose FETCH_SERVER_PROGRESS");
143 
144 	return got_privsep_flush_imsg(ibuf);
145 }
146 
147 static const struct got_error *
148 send_fetch_download_progress(struct imsgbuf *ibuf, off_t bytes,
149     struct got_ratelimit *rl)
150 {
151 	const struct got_error *err;
152 	int elapsed = 0;
153 
154 	if (rl) {
155 		err = got_ratelimit_check(&elapsed, rl);
156 		if (err || !elapsed)
157 			return err;
158 	}
159 
160 	if (imsg_compose(ibuf, GOT_IMSG_FETCH_DOWNLOAD_PROGRESS, 0, 0, -1,
161 	    &bytes, sizeof(bytes)) == -1)
162 		return got_error_from_errno(
163 		    "imsg_compose FETCH_DOWNLOAD_PROGRESS");
164 
165 	return got_privsep_flush_imsg(ibuf);
166 }
167 
168 static const struct got_error *
169 send_fetch_done(struct imsgbuf *ibuf, uint8_t *pack_sha1)
170 {
171 	if (imsg_compose(ibuf, GOT_IMSG_FETCH_DONE, 0, 0, -1,
172 	    pack_sha1, SHA1_DIGEST_LENGTH) == -1)
173 		return got_error_from_errno("imsg_compose FETCH");
174 	return got_privsep_flush_imsg(ibuf);
175 }
176 
177 static const struct got_error *
178 fetch_progress(struct imsgbuf *ibuf, const char *buf, size_t len)
179 {
180 	size_t i;
181 
182 	if (len == 0)
183 		return NULL;
184 
185 	/*
186 	 * Truncate messages which exceed the maximum imsg payload size.
187 	 * Server may send up to 64k.
188 	 */
189 	if (len > MAX_IMSGSIZE - IMSG_HEADER_SIZE)
190 		len = MAX_IMSGSIZE - IMSG_HEADER_SIZE;
191 
192 	/* Only allow printable ASCII. */
193 	for (i = 0; i < len; i++) {
194 		if (isprint((unsigned char)buf[i]) ||
195 		    isspace((unsigned char)buf[i]))
196 			continue;
197 		return got_error_msg(GOT_ERR_BAD_PACKET,
198 		    "non-printable progress message received from server");
199 	}
200 
201 	return send_fetch_server_progress(ibuf, buf, len);
202 }
203 
204 static const struct got_error *
205 fetch_error(const char *buf, size_t len)
206 {
207 	static char msg[1024];
208 	size_t i;
209 
210 	for (i = 0; i < len && i < sizeof(msg) - 1; i++) {
211 		if (!isprint((unsigned char)buf[i]))
212 			return got_error_msg(GOT_ERR_BAD_PACKET,
213 			    "non-printable error message received from server");
214 		msg[i] = buf[i];
215 	}
216 	msg[i] = '\0';
217 	return got_error_msg(GOT_ERR_FETCH_FAILED, msg);
218 }
219 
220 static const struct got_error *
221 send_fetch_symrefs(struct imsgbuf *ibuf, struct got_pathlist_head *symrefs)
222 {
223 	struct ibuf *wbuf;
224 	size_t len, nsymrefs = 0;
225 	struct got_pathlist_entry *pe;
226 
227 	len = sizeof(struct got_imsg_fetch_symrefs);
228 	TAILQ_FOREACH(pe, symrefs, entry) {
229 		const char *target = pe->data;
230 		len += sizeof(struct got_imsg_fetch_symref) +
231 		    pe->path_len + strlen(target);
232 		nsymrefs++;
233 	}
234 
235 	if (len >= MAX_IMSGSIZE - IMSG_HEADER_SIZE)
236 		return got_error(GOT_ERR_NO_SPACE);
237 
238 	wbuf = imsg_create(ibuf, GOT_IMSG_FETCH_SYMREFS, 0, 0, len);
239 	if (wbuf == NULL)
240 		return got_error_from_errno("imsg_create FETCH_SYMREFS");
241 
242 	/* Keep in sync with struct got_imsg_fetch_symrefs definition! */
243 	if (imsg_add(wbuf, &nsymrefs, sizeof(nsymrefs)) == -1)
244 		return got_error_from_errno("imsg_add FETCH_SYMREFS");
245 
246 	TAILQ_FOREACH(pe, symrefs, entry) {
247 		const char *name = pe->path;
248 		size_t name_len = pe->path_len;
249 		const char *target = pe->data;
250 		size_t target_len = strlen(target);
251 
252 		/* Keep in sync with struct got_imsg_fetch_symref definition! */
253 		if (imsg_add(wbuf, &name_len, sizeof(name_len)) == -1)
254 			return got_error_from_errno("imsg_add FETCH_SYMREFS");
255 		if (imsg_add(wbuf, &target_len, sizeof(target_len)) == -1)
256 			return got_error_from_errno("imsg_add FETCH_SYMREFS");
257 		if (imsg_add(wbuf, name, name_len) == -1)
258 			return got_error_from_errno("imsg_add FETCH_SYMREFS");
259 		if (imsg_add(wbuf, target, target_len) == -1)
260 			return got_error_from_errno("imsg_add FETCH_SYMREFS");
261 	}
262 
263 	wbuf->fd = -1;
264 	imsg_close(ibuf, wbuf);
265 	return got_privsep_flush_imsg(ibuf);
266 }
267 
268 static const struct got_error *
269 send_fetch_ref(struct imsgbuf *ibuf, struct got_object_id *refid,
270     const char *refname)
271 {
272 	struct ibuf *wbuf;
273 	size_t len, reflen = strlen(refname);
274 
275 	len = sizeof(struct got_imsg_fetch_ref) + reflen;
276 	if (len >= MAX_IMSGSIZE - IMSG_HEADER_SIZE)
277 		return got_error(GOT_ERR_NO_SPACE);
278 
279 	wbuf = imsg_create(ibuf, GOT_IMSG_FETCH_REF, 0, 0, len);
280 	if (wbuf == NULL)
281 		return got_error_from_errno("imsg_create FETCH_REF");
282 
283 	/* Keep in sync with struct got_imsg_fetch_ref definition! */
284 	if (imsg_add(wbuf, refid, sizeof(*refid)) == -1)
285 		return got_error_from_errno("imsg_add FETCH_REF");
286 	if (imsg_add(wbuf, refname, reflen) == -1)
287 		return got_error_from_errno("imsg_add FETCH_REF");
288 
289 	wbuf->fd = -1;
290 	imsg_close(ibuf, wbuf);
291 	return got_privsep_flush_imsg(ibuf);
292 }
293 
294 static const struct got_error *
295 fetch_ref(struct imsgbuf *ibuf, struct got_pathlist_head *have_refs,
296     struct got_object_id *have, struct got_object_id *want,
297     const char *refname, const char *id_str)
298 {
299 	const struct got_error *err;
300 	char *theirs = NULL, *mine = NULL;
301 
302 	if (!got_parse_sha1_digest(want->sha1, id_str)) {
303 		err = got_error(GOT_ERR_BAD_OBJ_ID_STR);
304 		goto done;
305 	}
306 
307 	match_remote_ref(have_refs, have, refname);
308 	err = send_fetch_ref(ibuf, want, refname);
309 	if (err)
310 		goto done;
311 
312 	if (chattygot)
313 		fprintf(stderr, "%s: %s will be fetched\n",
314 		    getprogname(), refname);
315 	if (chattygot > 1) {
316 		err = got_object_id_str(&theirs, want);
317 		if (err)
318 			goto done;
319 		err = got_object_id_str(&mine, have);
320 		if (err)
321 			goto done;
322 		fprintf(stderr, "%s: remote: %s\n%s: local:  %s\n",
323 		    getprogname(), theirs, getprogname(), mine);
324 	}
325 done:
326 	free(theirs);
327 	free(mine);
328 	return err;
329 }
330 
331 static const struct got_error *
332 fetch_pack(int fd, int packfd, uint8_t *pack_sha1,
333     struct got_pathlist_head *have_refs, int fetch_all_branches,
334     struct got_pathlist_head *wanted_branches,
335     struct got_pathlist_head *wanted_refs, int list_refs_only,
336     const char *worktree_branch, const char *remote_head,
337     int no_head, struct imsgbuf *ibuf)
338 {
339 	const struct got_error *err = NULL;
340 	char buf[GOT_PKT_MAX];
341 	char hashstr[SHA1_DIGEST_STRING_LENGTH];
342 	struct got_object_id *have, *want;
343 	int is_firstpkt = 1, nref = 0, refsz = 16;
344 	int i, n, nwant = 0, nhave = 0, acked = 0;
345 	off_t packsz = 0, last_reported_packsz = 0;
346 	char *id_str = NULL, *default_id_str = NULL, *refname = NULL;
347 	char *server_capabilities = NULL, *my_capabilities = NULL;
348 	const char *default_branch = NULL;
349 	struct got_pathlist_head symrefs;
350 	struct got_pathlist_entry *pe;
351 	int sent_my_capabilites = 0, have_sidebands = 0;
352 	int found_branch = 0;
353 	SHA1_CTX sha1_ctx;
354 	uint8_t sha1_buf[SHA1_DIGEST_LENGTH];
355 	size_t sha1_buf_len = 0;
356 	ssize_t w;
357 	struct got_ratelimit rl;
358 
359 	TAILQ_INIT(&symrefs);
360 	SHA1Init(&sha1_ctx);
361 	got_ratelimit_init(&rl, 0, 500);
362 
363 	have = malloc(refsz * sizeof(have[0]));
364 	if (have == NULL)
365 		return got_error_from_errno("malloc");
366 	want = malloc(refsz * sizeof(want[0]));
367 	if (want == NULL) {
368 		err = got_error_from_errno("malloc");
369 		goto done;
370 	}
371 	while (1) {
372 		err = got_pkt_readpkt(&n, fd, buf, sizeof(buf), chattygot);
373 		if (err)
374 			goto done;
375 		if (n == 0)
376 			break;
377 		if (n >= 4 && strncmp(buf, "ERR ", 4) == 0) {
378 			err = fetch_error(&buf[4], n - 4);
379 			goto done;
380 		}
381 		free(id_str);
382 		free(refname);
383 		err = got_gitproto_parse_refline(&id_str, &refname,
384 		    &server_capabilities, buf, n);
385 		if (err)
386 			goto done;
387 
388 		if (refsz == nref + 1) {
389 			struct got_object_id *h, *w;
390 
391 			refsz *= 2;
392 			h = reallocarray(have, refsz, sizeof(have[0]));
393 			if (h == NULL) {
394 				err = got_error_from_errno("reallocarray");
395 				goto done;
396 			}
397 			have = h;
398 			w = reallocarray(want, refsz, sizeof(want[0]));
399 			if (w == NULL) {
400 				err = got_error_from_errno("reallocarray");
401 				goto done;
402 			}
403 			want = w;
404 		}
405 
406 		if (is_firstpkt) {
407 			if (chattygot && server_capabilities[0] != '\0')
408 				fprintf(stderr, "%s: server capabilities: %s\n",
409 				    getprogname(), server_capabilities);
410 			err = got_gitproto_match_capabilities(&my_capabilities,
411 			    &symrefs, server_capabilities,
412 			    got_capabilities, nitems(got_capabilities));
413 			if (err)
414 				goto done;
415 			if (chattygot)
416 				fprintf(stderr, "%s: my capabilities:%s\n",
417 				    getprogname(), my_capabilities != NULL ?
418 				    my_capabilities : "");
419 			err = send_fetch_symrefs(ibuf, &symrefs);
420 			if (err)
421 				goto done;
422 			is_firstpkt = 0;
423 			if (!fetch_all_branches) {
424 				TAILQ_FOREACH(pe, &symrefs, entry) {
425 					const char *name = pe->path;
426 					const char *symref_target = pe->data;
427 					if (strcmp(name, GOT_REF_HEAD) != 0)
428 						continue;
429 					default_branch = symref_target;
430 					break;
431 				}
432 			}
433 			if (default_branch)
434 				continue;
435 		}
436 		if (strstr(refname, "^{}")) {
437 			if (chattygot) {
438 				fprintf(stderr, "%s: ignoring %s\n",
439 				    getprogname(), refname);
440 			}
441 			continue;
442 		}
443 		if (default_branch && default_id_str == NULL &&
444 		    strcmp(refname, default_branch) == 0) {
445 			default_id_str = strdup(id_str);
446 			if (default_id_str == NULL) {
447 				err = got_error_from_errno("strdup");
448 				goto done;
449 			}
450 		}
451 
452 		if (list_refs_only || strncmp(refname, "refs/tags/", 10) == 0) {
453 			err = fetch_ref(ibuf, have_refs, &have[nref],
454 			    &want[nref], refname, id_str);
455 			if (err)
456 				goto done;
457 			nref++;
458 		} else if (strncmp(refname, "refs/heads/", 11) == 0) {
459 			if (fetch_all_branches) {
460 				err = fetch_ref(ibuf, have_refs, &have[nref],
461 				    &want[nref], refname, id_str);
462 				if (err)
463 					goto done;
464 				nref++;
465 				found_branch = 1;
466 				continue;
467 			}
468 			TAILQ_FOREACH(pe, wanted_branches, entry) {
469 				if (match_branch(refname, pe->path))
470 					break;
471 			}
472 			if (pe != NULL || (worktree_branch != NULL &&
473 			    match_branch(refname, worktree_branch))) {
474 				err = fetch_ref(ibuf, have_refs, &have[nref],
475 				    &want[nref], refname, id_str);
476 				if (err)
477 					goto done;
478 				nref++;
479 				found_branch = 1;
480 			} else if (chattygot) {
481 				fprintf(stderr, "%s: ignoring %s\n",
482 				    getprogname(), refname);
483 			}
484 		} else {
485 			TAILQ_FOREACH(pe, wanted_refs, entry) {
486 				if (match_wanted_ref(refname, pe->path))
487 					break;
488 			}
489 			if (pe != NULL) {
490 				err = fetch_ref(ibuf, have_refs, &have[nref],
491 				    &want[nref], refname, id_str);
492 				if (err)
493 					goto done;
494 				nref++;
495 			} else if (chattygot) {
496 				fprintf(stderr, "%s: ignoring %s\n",
497 				    getprogname(), refname);
498 			}
499 		}
500 	}
501 
502 	if (list_refs_only)
503 		goto done;
504 
505 	/*
506 	 * If -b was not used and either none of the requested branches
507 	 * (got.conf, worktree) were found or the client already has the
508 	 * remote HEAD symref but its target changed, fetch remote's HEAD.
509 	 */
510 	if (!no_head && default_branch && default_id_str &&
511 	    strncmp(default_branch, "refs/heads/", 11) == 0) {
512 		int remote_head_changed = 0;
513 
514 		if (remote_head) {
515 			if (strcmp(remote_head, default_branch + 11) != 0)
516 				remote_head_changed = 1;
517 		}
518 
519 		if (!found_branch || remote_head_changed) {
520 			err = fetch_ref(ibuf, have_refs, &have[nref],
521 			    &want[nref], default_branch, default_id_str);
522 			if (err)
523 				goto done;
524 			nref++;
525 		}
526 	}
527 
528 	/* Abort if we haven't found anything to fetch. */
529 	if (nref == 0) {
530 		struct got_pathlist_entry *pe;
531 		static char msg[PATH_MAX + 33];
532 
533 		pe = TAILQ_FIRST(wanted_branches);
534 		if (pe) {
535 			snprintf(msg, sizeof(msg),
536 			    "branch \"%s\" not found on server", pe->path);
537 			err = got_error_msg(GOT_ERR_FETCH_NO_BRANCH, msg);
538 			goto done;
539 		}
540 
541 		pe = TAILQ_FIRST(wanted_refs);
542 		if (pe) {
543 			snprintf(msg, sizeof(msg),
544 			    "reference \"%s\" not found on server", pe->path);
545 			err = got_error_msg(GOT_ERR_FETCH_NO_BRANCH, msg);
546 			goto done;
547 		}
548 
549 		err = got_error(GOT_ERR_FETCH_NO_BRANCH);
550 		goto done;
551 	}
552 
553 	for (i = 0; i < nref; i++) {
554 		if (got_object_id_cmp(&have[i], &want[i]) == 0)
555 			continue;
556 		got_sha1_digest_to_str(want[i].sha1, hashstr, sizeof(hashstr));
557 		n = snprintf(buf, sizeof(buf), "want %s%s\n", hashstr,
558 		    sent_my_capabilites || my_capabilities == NULL ?
559 		    "" : my_capabilities);
560 		if (n < 0 || (size_t)n >= sizeof(buf)) {
561 			err = got_error(GOT_ERR_NO_SPACE);
562 			goto done;
563 		}
564 		err = got_pkt_writepkt(fd, buf, n, chattygot);
565 		if (err)
566 			goto done;
567 		sent_my_capabilites = 1;
568 		nwant++;
569 	}
570 	err = got_pkt_flushpkt(fd, chattygot);
571 	if (err)
572 		goto done;
573 
574 	if (nwant == 0)
575 		goto done;
576 
577 	TAILQ_FOREACH(pe, have_refs, entry) {
578 		struct got_object_id *id = pe->data;
579 		got_sha1_digest_to_str(id->sha1, hashstr, sizeof(hashstr));
580 		n = snprintf(buf, sizeof(buf), "have %s\n", hashstr);
581 		if (n < 0 || (size_t)n >= sizeof(buf)) {
582 			err = got_error(GOT_ERR_NO_SPACE);
583 			goto done;
584 		}
585 		err = got_pkt_writepkt(fd, buf, n, chattygot);
586 		if (err)
587 			goto done;
588 		nhave++;
589 	}
590 
591 	n = strlcpy(buf, "done\n", sizeof(buf));
592 	err = got_pkt_writepkt(fd, buf, n, chattygot);
593 	if (err)
594 		goto done;
595 
596 	while (nhave > 0 && !acked) {
597 		struct got_object_id common_id;
598 
599 		/* The server should ACK the object IDs we need. */
600 		err = got_pkt_readpkt(&n, fd, buf, sizeof(buf), chattygot);
601 		if (err)
602 			goto done;
603 		if (n >= 4 && strncmp(buf, "ERR ", 4) == 0) {
604 			err = fetch_error(&buf[4], n - 4);
605 			goto done;
606 		}
607 		if (n >= 4 && strncmp(buf, "NAK\n", 4) == 0) {
608 			/*
609 			 * Server could not find a common ancestor.
610 			 * Perhaps it is an out-of-date mirror, or there
611 			 * is a repository with unrelated history.
612 			 */
613 			break;
614 		}
615 		if (n < 4 + SHA1_DIGEST_STRING_LENGTH ||
616 		    strncmp(buf, "ACK ", 4) != 0) {
617 			err = got_error_msg(GOT_ERR_BAD_PACKET,
618 			    "unexpected message from server");
619 			goto done;
620 		}
621 		if (!got_parse_sha1_digest(common_id.sha1, buf + 4)) {
622 			err = got_error_msg(GOT_ERR_BAD_PACKET,
623 			    "bad object ID in ACK packet from server");
624 			goto done;
625 		}
626 		acked++;
627 	}
628 
629 	if (nhave == 0) {
630 		err = got_pkt_readpkt(&n, fd, buf, sizeof(buf), chattygot);
631 		if (err)
632 			goto done;
633 		if (n != 4 || strncmp(buf, "NAK\n", n) != 0) {
634 			err = got_error_msg(GOT_ERR_BAD_PACKET,
635 			    "unexpected message from server");
636 			goto done;
637 		}
638 	}
639 
640 	if (chattygot)
641 		fprintf(stderr, "%s: fetching...\n", getprogname());
642 
643 	if (my_capabilities != NULL &&
644 	    strstr(my_capabilities, GOT_CAPA_SIDE_BAND_64K) != NULL)
645 		have_sidebands = 1;
646 
647 	while (1) {
648 		ssize_t r = 0;
649 		int datalen = -1;
650 
651 		if (have_sidebands) {
652 			err = got_pkt_readhdr(&datalen, fd, chattygot);
653 			if (err)
654 				goto done;
655 			if (datalen <= 0)
656 				break;
657 
658 			/* Read sideband channel ID (one byte). */
659 			r = read(fd, buf, 1);
660 			if (r == -1) {
661 				err = got_error_from_errno("read");
662 				goto done;
663 			}
664 			if (r != 1) {
665 				err = got_error_msg(GOT_ERR_BAD_PACKET,
666 				    "short packet");
667 				goto done;
668 			}
669 			if (datalen > sizeof(buf) - 5) {
670 				err = got_error_msg(GOT_ERR_BAD_PACKET,
671 				    "bad packet length");
672 				goto done;
673 			}
674 			datalen--; /* sideband ID has been read */
675 			if (buf[0] == GOT_SIDEBAND_PACKFILE_DATA) {
676 				/* Read packfile data. */
677 				err = got_pkt_readn(&r, fd, buf, datalen);
678 				if (err)
679 					goto done;
680 				if (r != datalen) {
681 					err = got_error_msg(GOT_ERR_BAD_PACKET,
682 					    "packet too short");
683 					goto done;
684 				}
685 			} else if (buf[0] == GOT_SIDEBAND_PROGRESS_INFO) {
686 				err = got_pkt_readn(&r, fd, buf, datalen);
687 				if (err)
688 					goto done;
689 				if (r != datalen) {
690 					err = got_error_msg(GOT_ERR_BAD_PACKET,
691 					    "packet too short");
692 					goto done;
693 				}
694 				err = fetch_progress(ibuf, buf, r);
695 				if (err)
696 					goto done;
697 				continue;
698 			} else if (buf[0] == GOT_SIDEBAND_ERROR_INFO) {
699 				err = got_pkt_readn(&r, fd, buf, datalen);
700 				if (err)
701 					goto done;
702 				if (r != datalen) {
703 					err = got_error_msg(GOT_ERR_BAD_PACKET,
704 					    "packet too short");
705 					goto done;
706 				}
707 				err = fetch_error(buf, r);
708 				goto done;
709 			} else if (buf[0] == 'A') {
710 				err = got_pkt_readn(&r, fd, buf, datalen);
711 				if (err)
712 					goto done;
713 				if (r != datalen) {
714 					err = got_error_msg(GOT_ERR_BAD_PACKET,
715 					    "packet too short");
716 					goto done;
717 				}
718 				/*
719 				 * Git server responds with ACK after 'done'
720 				 * even though multi_ack is disabled?!?
721 				 */
722 				buf[r] = '\0';
723 				if (strncmp(buf, "CK ", 3) == 0)
724 					continue; /* ignore */
725 				err = got_error_msg(GOT_ERR_BAD_PACKET,
726 				    "unexpected message from server");
727 				goto done;
728 			} else {
729 				err = got_error_msg(GOT_ERR_BAD_PACKET,
730 				    "unknown side-band received from server");
731 				goto done;
732 			}
733 		} else {
734 			/* No sideband channel. Every byte is packfile data. */
735 			err = got_pkt_readn(&r, fd, buf, sizeof buf);
736 			if (err)
737 				goto done;
738 			if (r <= 0)
739 				break;
740 		}
741 
742 		/*
743 		 * An expected SHA1 checksum sits at the end of the pack file.
744 		 * Since we don't know the file size ahead of time we have to
745 		 * keep SHA1_DIGEST_LENGTH bytes buffered and avoid mixing
746 		 * those bytes into our SHA1 checksum computation until we
747 		 * know for sure that additional pack file data bytes follow.
748 		 *
749 		 * We can assume r > 0 since otherwise the loop would exit.
750 		 */
751 		if (r < SHA1_DIGEST_LENGTH) {
752 			if (sha1_buf_len < SHA1_DIGEST_LENGTH) {
753 				/*
754 				 * If there's enough buffered + read data to
755 				 * fill up the buffer then shift a sufficient
756 				 * amount of bytes out at the front to make
757 				 * room, mixing those bytes into the checksum.
758 				 */
759 				if (sha1_buf_len > 0 &&
760 				    sha1_buf_len + r > SHA1_DIGEST_LENGTH) {
761 					size_t nshift = MIN(sha1_buf_len + r -
762 					    SHA1_DIGEST_LENGTH, sha1_buf_len);
763 					SHA1Update(&sha1_ctx, sha1_buf, nshift);
764 					memmove(sha1_buf, sha1_buf + nshift,
765 					    sha1_buf_len - nshift);
766 					sha1_buf_len -= nshift;
767 				}
768 
769 				/* Buffer potential checksum bytes. */
770 				memcpy(sha1_buf + sha1_buf_len, buf, r);
771 				sha1_buf_len += r;
772 			} else {
773 				/*
774 				 * Mix in previously buffered bytes which
775 				 * are not part of the checksum after all.
776 				 */
777 				SHA1Update(&sha1_ctx, sha1_buf, r);
778 
779 				/* Update potential checksum buffer. */
780 				memmove(sha1_buf, sha1_buf + r,
781 				    sha1_buf_len - r);
782 				memcpy(sha1_buf + sha1_buf_len - r, buf, r);
783 			}
784 		} else {
785 			/* Mix in any previously buffered bytes. */
786 			SHA1Update(&sha1_ctx, sha1_buf, sha1_buf_len);
787 
788 			/* Mix in bytes read minus potential checksum bytes. */
789 			SHA1Update(&sha1_ctx, buf, r - SHA1_DIGEST_LENGTH);
790 
791 			/* Buffer potential checksum bytes. */
792 			memcpy(sha1_buf, buf + r - SHA1_DIGEST_LENGTH,
793 			    SHA1_DIGEST_LENGTH);
794 			sha1_buf_len = SHA1_DIGEST_LENGTH;
795 		}
796 
797 		/* Write packfile data to temporary pack file. */
798 		w = write(packfd, buf, r);
799 		if (w == -1) {
800 			err = got_error_from_errno("write");
801 			goto done;
802 		}
803 		if (w != r) {
804 			err = got_error(GOT_ERR_IO);
805 			goto done;
806 		}
807 		packsz += w;
808 
809 		/* Don't send too many progress privsep messages. */
810 		if (packsz > last_reported_packsz + 1024) {
811 			err = send_fetch_download_progress(ibuf, packsz, &rl);
812 			if (err)
813 				goto done;
814 			last_reported_packsz = packsz;
815 		}
816 	}
817 	err = send_fetch_download_progress(ibuf, packsz, NULL);
818 	if (err)
819 		goto done;
820 
821 	SHA1Final(pack_sha1, &sha1_ctx);
822 	if (sha1_buf_len != SHA1_DIGEST_LENGTH ||
823 	    memcmp(pack_sha1, sha1_buf, sha1_buf_len) != 0) {
824 		err = got_error_msg(GOT_ERR_BAD_PACKFILE,
825 		    "pack file checksum mismatch");
826 	}
827 done:
828 	got_pathlist_free(&symrefs, GOT_PATHLIST_FREE_ALL);
829 	free(have);
830 	free(want);
831 	free(id_str);
832 	free(default_id_str);
833 	free(refname);
834 	free(server_capabilities);
835 	return err;
836 }
837 
838 
839 int
840 main(int argc, char **argv)
841 {
842 	const struct got_error *err = NULL;
843 	int fetchfd = -1, packfd = -1;
844 	uint8_t pack_sha1[SHA1_DIGEST_LENGTH];
845 	struct imsgbuf ibuf;
846 	struct imsg imsg;
847 	struct got_pathlist_head have_refs;
848 	struct got_pathlist_head wanted_branches;
849 	struct got_pathlist_head wanted_refs;
850 	struct got_imsg_fetch_request fetch_req;
851 	struct got_imsg_fetch_have_ref href;
852 	struct got_imsg_fetch_wanted_branch wbranch;
853 	struct got_imsg_fetch_wanted_ref wref;
854 	size_t datalen, i;
855 	char *remote_head = NULL, *worktree_branch = NULL;
856 #if 0
857 	static int attached;
858 	while (!attached)
859 		sleep (1);
860 #endif
861 
862 	TAILQ_INIT(&have_refs);
863 	TAILQ_INIT(&wanted_branches);
864 	TAILQ_INIT(&wanted_refs);
865 
866 	imsg_init(&ibuf, GOT_IMSG_FD_CHILD);
867 #ifndef PROFILE
868 	/* revoke access to most system calls */
869 	if (pledge("stdio recvfd", NULL) == -1) {
870 		err = got_error_from_errno("pledge");
871 		got_privsep_send_error(&ibuf, err);
872 		return 1;
873 	}
874 #endif
875 	err = got_privsep_recv_imsg(&imsg, &ibuf, 0);
876 	if (err) {
877 		if (err->code == GOT_ERR_PRIVSEP_PIPE)
878 			err = NULL;
879 		goto done;
880 	}
881 	if (imsg.hdr.type == GOT_IMSG_STOP)
882 		goto done;
883 	if (imsg.hdr.type != GOT_IMSG_FETCH_REQUEST) {
884 		err = got_error(GOT_ERR_PRIVSEP_MSG);
885 		goto done;
886 	}
887 	datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
888 	if (datalen < sizeof(fetch_req)) {
889 		err = got_error(GOT_ERR_PRIVSEP_LEN);
890 		goto done;
891 	}
892 	memcpy(&fetch_req, imsg.data, sizeof(fetch_req));
893 	fetchfd = imsg.fd;
894 
895 	if (datalen != sizeof(fetch_req) +
896 	    fetch_req.worktree_branch_len + fetch_req.remote_head_len) {
897 		err = got_error(GOT_ERR_PRIVSEP_LEN);
898 		goto done;
899 	}
900 
901 	if (fetch_req.worktree_branch_len != 0) {
902 		worktree_branch = strndup(imsg.data +
903 		    sizeof(fetch_req), fetch_req.worktree_branch_len);
904 		if (worktree_branch == NULL) {
905 			err = got_error_from_errno("strndup");
906 			goto done;
907 		}
908 	}
909 
910 	if (fetch_req.remote_head_len != 0) {
911 		remote_head = strndup(imsg.data + sizeof(fetch_req) +
912 		    fetch_req.worktree_branch_len, fetch_req.remote_head_len);
913 		if (remote_head == NULL) {
914 			err = got_error_from_errno("strndup");
915 			goto done;
916 		}
917 	}
918 
919 	imsg_free(&imsg);
920 
921 	if (fetch_req.verbosity > 0)
922 		chattygot += fetch_req.verbosity;
923 
924 	for (i = 0; i < fetch_req.n_have_refs; i++) {
925 		struct got_object_id *id;
926 		char *refname;
927 
928 		err = got_privsep_recv_imsg(&imsg, &ibuf, 0);
929 		if (err) {
930 			if (err->code == GOT_ERR_PRIVSEP_PIPE)
931 				err = NULL;
932 			goto done;
933 		}
934 		if (imsg.hdr.type == GOT_IMSG_STOP)
935 			goto done;
936 		if (imsg.hdr.type != GOT_IMSG_FETCH_HAVE_REF) {
937 			err = got_error(GOT_ERR_PRIVSEP_MSG);
938 			goto done;
939 		}
940 		datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
941 		if (datalen < sizeof(href)) {
942 			err = got_error(GOT_ERR_PRIVSEP_LEN);
943 			goto done;
944 		}
945 		memcpy(&href, imsg.data, sizeof(href));
946 		if (datalen - sizeof(href) < href.name_len) {
947 			err = got_error(GOT_ERR_PRIVSEP_LEN);
948 			goto done;
949 		}
950 		refname = strndup(imsg.data + sizeof(href), href.name_len);
951 		if (refname == NULL) {
952 			err = got_error_from_errno("strndup");
953 			goto done;
954 		}
955 
956 		id = malloc(sizeof(*id));
957 		if (id == NULL) {
958 			free(refname);
959 			err = got_error_from_errno("malloc");
960 			goto done;
961 		}
962 		memcpy(id, &href.id, sizeof(*id));
963 		err = got_pathlist_append(&have_refs, refname, id);
964 		if (err) {
965 			free(refname);
966 			free(id);
967 			goto done;
968 		}
969 
970 		imsg_free(&imsg);
971 	}
972 
973 	for (i = 0; i < fetch_req.n_wanted_branches; i++) {
974 		char *refname;
975 
976 		err = got_privsep_recv_imsg(&imsg, &ibuf, 0);
977 		if (err) {
978 			if (err->code == GOT_ERR_PRIVSEP_PIPE)
979 				err = NULL;
980 			goto done;
981 		}
982 		if (imsg.hdr.type == GOT_IMSG_STOP)
983 			goto done;
984 		if (imsg.hdr.type != GOT_IMSG_FETCH_WANTED_BRANCH) {
985 			err = got_error(GOT_ERR_PRIVSEP_MSG);
986 			goto done;
987 		}
988 		datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
989 		if (datalen < sizeof(wbranch)) {
990 			err = got_error(GOT_ERR_PRIVSEP_LEN);
991 			goto done;
992 		}
993 		memcpy(&wbranch, imsg.data, sizeof(wbranch));
994 		if (datalen - sizeof(wbranch) < wbranch.name_len) {
995 			err = got_error(GOT_ERR_PRIVSEP_LEN);
996 			goto done;
997 		}
998 		refname = strndup(imsg.data + sizeof(wbranch),
999 		    wbranch.name_len);
1000 		if (refname == NULL) {
1001 			err = got_error_from_errno("strndup");
1002 			goto done;
1003 		}
1004 
1005 		err = got_pathlist_append(&wanted_branches, refname, NULL);
1006 		if (err) {
1007 			free(refname);
1008 			goto done;
1009 		}
1010 
1011 		imsg_free(&imsg);
1012 	}
1013 
1014 	for (i = 0; i < fetch_req.n_wanted_refs; i++) {
1015 		char *refname;
1016 
1017 		err = got_privsep_recv_imsg(&imsg, &ibuf, 0);
1018 		if (err) {
1019 			if (err->code == GOT_ERR_PRIVSEP_PIPE)
1020 				err = NULL;
1021 			goto done;
1022 		}
1023 		if (imsg.hdr.type == GOT_IMSG_STOP)
1024 			goto done;
1025 		if (imsg.hdr.type != GOT_IMSG_FETCH_WANTED_REF) {
1026 			err = got_error(GOT_ERR_PRIVSEP_MSG);
1027 			goto done;
1028 		}
1029 		datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
1030 		if (datalen < sizeof(wref)) {
1031 			err = got_error(GOT_ERR_PRIVSEP_LEN);
1032 			goto done;
1033 		}
1034 		memcpy(&wref, imsg.data, sizeof(wref));
1035 		if (datalen - sizeof(wref) < wref.name_len) {
1036 			err = got_error(GOT_ERR_PRIVSEP_LEN);
1037 			goto done;
1038 		}
1039 		refname = strndup(imsg.data + sizeof(wref), wref.name_len);
1040 		if (refname == NULL) {
1041 			err = got_error_from_errno("strndup");
1042 			goto done;
1043 		}
1044 
1045 		err = got_pathlist_append(&wanted_refs, refname, NULL);
1046 		if (err) {
1047 			free(refname);
1048 			goto done;
1049 		}
1050 
1051 		imsg_free(&imsg);
1052 	}
1053 
1054 	err = got_privsep_recv_imsg(&imsg, &ibuf, 0);
1055 	if (err) {
1056 		if (err->code == GOT_ERR_PRIVSEP_PIPE)
1057 			err = NULL;
1058 		goto done;
1059 	}
1060 	if (imsg.hdr.type == GOT_IMSG_STOP)
1061 		goto done;
1062 	if (imsg.hdr.type != GOT_IMSG_FETCH_OUTFD) {
1063 		err = got_error(GOT_ERR_PRIVSEP_MSG);
1064 		goto done;
1065 	}
1066 	if (imsg.hdr.len - IMSG_HEADER_SIZE != 0) {
1067 		err = got_error(GOT_ERR_PRIVSEP_LEN);
1068 		goto done;
1069 	}
1070 	packfd = imsg.fd;
1071 
1072 	err = fetch_pack(fetchfd, packfd, pack_sha1, &have_refs,
1073 	    fetch_req.fetch_all_branches, &wanted_branches,
1074 	    &wanted_refs, fetch_req.list_refs_only,
1075 	    worktree_branch, remote_head, fetch_req.no_head, &ibuf);
1076 done:
1077 	free(worktree_branch);
1078 	free(remote_head);
1079 	got_pathlist_free(&have_refs, GOT_PATHLIST_FREE_ALL);
1080 	got_pathlist_free(&wanted_branches, GOT_PATHLIST_FREE_PATH);
1081 	if (fetchfd != -1 && close(fetchfd) == -1 && err == NULL)
1082 		err = got_error_from_errno("close");
1083 	if (packfd != -1 && close(packfd) == -1 && err == NULL)
1084 		err = got_error_from_errno("close");
1085 	if (err != NULL)
1086 		got_privsep_send_error(&ibuf, err);
1087 	else
1088 		err = send_fetch_done(&ibuf, pack_sha1);
1089 	if (err != NULL) {
1090 		fprintf(stderr, "%s: %s\n", getprogname(), err->msg);
1091 		got_privsep_send_error(&ibuf, err);
1092 	}
1093 
1094 	exit(0);
1095 }