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 <sha2.h>
34 #include <fcntl.h>
35 #include <unistd.h>
36 #include <zlib.h>
37 #include <err.h>
38 
39 #include "got_error.h"
40 #include "got_object.h"
41 #include "got_path.h"
42 #include "got_version.h"
43 #include "got_fetch.h"
44 #include "got_reference.h"
45 
46 #include "got_lib_hash.h"
47 #include "got_lib_delta.h"
48 #include "got_lib_object.h"
49 #include "got_lib_object_parse.h"
50 #include "got_lib_privsep.h"
51 #include "got_lib_pack.h"
52 #include "got_lib_pkt.h"
53 #include "got_lib_gitproto.h"
54 #include "got_lib_ratelimit.h"
55 
56 #ifndef MIN
57 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
58 #endif
59 
60 #ifndef nitems
61 #define nitems(_a)	(sizeof((_a)) / sizeof((_a)[0]))
62 #endif
63 
64 struct got_object *indexed;
65 static int chattygot;
66 
67 static const struct got_capability got_capabilities[] = {
68 	{ GOT_CAPA_AGENT, "got/" GOT_VERSION_STR },
69 	{ GOT_CAPA_OFS_DELTA, NULL },
70 	{ GOT_CAPA_SIDE_BAND_64K, NULL },
71 };
72 
73 static void
74 match_remote_ref(struct got_pathlist_head *have_refs,
75     struct got_object_id *my_id, const char *refname)
76 {
77 	struct got_pathlist_entry *pe;
78 
79 	/* XXX zero-hash signifies we don't have this ref;
80 	 * we should use a flag instead */
81 	memset(my_id, 0, sizeof(*my_id));
82 
83 	TAILQ_FOREACH(pe, have_refs, entry) {
84 		struct got_object_id *id = pe->data;
85 		if (strcmp(pe->path, refname) == 0) {
86 			memcpy(my_id, id, sizeof(*my_id));
87 			break;
88 		}
89 	}
90 }
91 
92 static int
93 match_branch(const char *branch, const char *wanted_branch)
94 {
95 	if (strncmp(branch, "refs/heads/", 11) != 0)
96 		return 0;
97 
98 	if (strncmp(wanted_branch, "refs/heads/", 11) == 0)
99 		wanted_branch += 11;
100 
101 	return (strcmp(branch + 11, wanted_branch) == 0);
102 }
103 
104 static int
105 match_wanted_ref(const char *refname, const char *wanted_ref)
106 {
107 	if (strncmp(refname, "refs/", 5) != 0)
108 		return 0;
109 	refname += 5;
110 
111 	/*
112 	 * Prevent fetching of references that won't make any
113 	 * sense outside of the remote repository's context.
114 	 */
115 	if (strncmp(refname, "got/", 4) == 0)
116 		return 0;
117 	if (strncmp(refname, "remotes/", 8) == 0)
118 		return 0;
119 
120 	if (strncmp(wanted_ref, "refs/", 5) == 0)
121 		wanted_ref += 5;
122 
123 	/* Allow prefix match. */
124 	if (got_path_is_child(refname, wanted_ref, strlen(wanted_ref)))
125 		return 1;
126 
127 	/* Allow exact match. */
128 	return (strcmp(refname, wanted_ref) == 0);
129 }
130 
131 static const struct got_error *
132 send_fetch_server_progress(struct imsgbuf *ibuf, const char *msg, size_t msglen)
133 {
134 	if (msglen > MAX_IMSGSIZE - IMSG_HEADER_SIZE)
135 		return got_error(GOT_ERR_NO_SPACE);
136 
137 	if (msglen == 0)
138 		return NULL;
139 
140 	if (imsg_compose(ibuf, GOT_IMSG_FETCH_SERVER_PROGRESS, 0, 0, -1,
141 	    msg, msglen) == -1)
142 		return got_error_from_errno(
143 		    "imsg_compose FETCH_SERVER_PROGRESS");
144 
145 	return got_privsep_flush_imsg(ibuf);
146 }
147 
148 static const struct got_error *
149 send_fetch_download_progress(struct imsgbuf *ibuf, off_t bytes,
150     struct got_ratelimit *rl)
151 {
152 	const struct got_error *err;
153 	int elapsed = 0;
154 
155 	if (rl) {
156 		err = got_ratelimit_check(&elapsed, rl);
157 		if (err || !elapsed)
158 			return err;
159 	}
160 
161 	if (imsg_compose(ibuf, GOT_IMSG_FETCH_DOWNLOAD_PROGRESS, 0, 0, -1,
162 	    &bytes, sizeof(bytes)) == -1)
163 		return got_error_from_errno(
164 		    "imsg_compose FETCH_DOWNLOAD_PROGRESS");
165 
166 	return got_privsep_flush_imsg(ibuf);
167 }
168 
169 static const struct got_error *
170 send_fetch_done(struct imsgbuf *ibuf, uint8_t *pack_sha1)
171 {
172 	if (imsg_compose(ibuf, GOT_IMSG_FETCH_DONE, 0, 0, -1,
173 	    pack_sha1, SHA1_DIGEST_LENGTH) == -1)
174 		return got_error_from_errno("imsg_compose FETCH");
175 	return got_privsep_flush_imsg(ibuf);
176 }
177 
178 static const struct got_error *
179 fetch_progress(struct imsgbuf *ibuf, const char *buf, size_t len)
180 {
181 	size_t i;
182 
183 	if (len == 0)
184 		return NULL;
185 
186 	/*
187 	 * Truncate messages which exceed the maximum imsg payload size.
188 	 * Server may send up to 64k.
189 	 */
190 	if (len > MAX_IMSGSIZE - IMSG_HEADER_SIZE)
191 		len = MAX_IMSGSIZE - IMSG_HEADER_SIZE;
192 
193 	/* Only allow printable ASCII. */
194 	for (i = 0; i < len; i++) {
195 		if (isprint((unsigned char)buf[i]) ||
196 		    isspace((unsigned char)buf[i]))
197 			continue;
198 		return got_error_msg(GOT_ERR_BAD_PACKET,
199 		    "non-printable progress message received from server");
200 	}
201 
202 	return send_fetch_server_progress(ibuf, buf, len);
203 }
204 
205 static const struct got_error *
206 fetch_error(const char *buf, size_t len)
207 {
208 	static char msg[1024];
209 	size_t i;
210 
211 	for (i = 0; i < len && i < sizeof(msg) - 1; i++) {
212 		if (!isprint((unsigned char)buf[i]))
213 			return got_error_msg(GOT_ERR_BAD_PACKET,
214 			    "non-printable error message received from server");
215 		msg[i] = buf[i];
216 	}
217 	msg[i] = '\0';
218 	return got_error_msg(GOT_ERR_FETCH_FAILED, msg);
219 }
220 
221 static const struct got_error *
222 send_fetch_symrefs(struct imsgbuf *ibuf, struct got_pathlist_head *symrefs)
223 {
224 	struct ibuf *wbuf;
225 	size_t len, nsymrefs = 0;
226 	struct got_pathlist_entry *pe;
227 
228 	len = sizeof(struct got_imsg_fetch_symrefs);
229 	TAILQ_FOREACH(pe, symrefs, entry) {
230 		const char *target = pe->data;
231 		len += sizeof(struct got_imsg_fetch_symref) +
232 		    pe->path_len + strlen(target);
233 		nsymrefs++;
234 	}
235 
236 	if (len >= MAX_IMSGSIZE - IMSG_HEADER_SIZE)
237 		return got_error(GOT_ERR_NO_SPACE);
238 
239 	wbuf = imsg_create(ibuf, GOT_IMSG_FETCH_SYMREFS, 0, 0, len);
240 	if (wbuf == NULL)
241 		return got_error_from_errno("imsg_create FETCH_SYMREFS");
242 
243 	/* Keep in sync with struct got_imsg_fetch_symrefs definition! */
244 	if (imsg_add(wbuf, &nsymrefs, sizeof(nsymrefs)) == -1)
245 		return got_error_from_errno("imsg_add FETCH_SYMREFS");
246 
247 	TAILQ_FOREACH(pe, symrefs, entry) {
248 		const char *name = pe->path;
249 		size_t name_len = pe->path_len;
250 		const char *target = pe->data;
251 		size_t target_len = strlen(target);
252 
253 		/* Keep in sync with struct got_imsg_fetch_symref definition! */
254 		if (imsg_add(wbuf, &name_len, sizeof(name_len)) == -1)
255 			return got_error_from_errno("imsg_add FETCH_SYMREFS");
256 		if (imsg_add(wbuf, &target_len, sizeof(target_len)) == -1)
257 			return got_error_from_errno("imsg_add FETCH_SYMREFS");
258 		if (imsg_add(wbuf, name, name_len) == -1)
259 			return got_error_from_errno("imsg_add FETCH_SYMREFS");
260 		if (imsg_add(wbuf, target, target_len) == -1)
261 			return got_error_from_errno("imsg_add FETCH_SYMREFS");
262 	}
263 
264 	wbuf->fd = -1;
265 	imsg_close(ibuf, wbuf);
266 	return got_privsep_flush_imsg(ibuf);
267 }
268 
269 static const struct got_error *
270 send_fetch_ref(struct imsgbuf *ibuf, struct got_object_id *refid,
271     const char *refname)
272 {
273 	struct ibuf *wbuf;
274 	size_t len, reflen = strlen(refname);
275 
276 	len = sizeof(struct got_imsg_fetch_ref) + reflen;
277 	if (len >= MAX_IMSGSIZE - IMSG_HEADER_SIZE)
278 		return got_error(GOT_ERR_NO_SPACE);
279 
280 	wbuf = imsg_create(ibuf, GOT_IMSG_FETCH_REF, 0, 0, len);
281 	if (wbuf == NULL)
282 		return got_error_from_errno("imsg_create FETCH_REF");
283 
284 	/* Keep in sync with struct got_imsg_fetch_ref definition! */
285 	if (imsg_add(wbuf, refid, sizeof(*refid)) == -1)
286 		return got_error_from_errno("imsg_add FETCH_REF");
287 	if (imsg_add(wbuf, refname, reflen) == -1)
288 		return got_error_from_errno("imsg_add FETCH_REF");
289 
290 	wbuf->fd = -1;
291 	imsg_close(ibuf, wbuf);
292 	return got_privsep_flush_imsg(ibuf);
293 }
294 
295 static const struct got_error *
296 fetch_ref(struct imsgbuf *ibuf, struct got_pathlist_head *have_refs,
297     struct got_object_id *have, struct got_object_id *want,
298     const char *refname, const char *id_str)
299 {
300 	const struct got_error *err;
301 	char *theirs = NULL, *mine = NULL;
302 
303 	if (!got_parse_object_id(want, id_str, GOT_HASH_SHA1)) {
304 		err = got_error(GOT_ERR_BAD_OBJ_ID_STR);
305 		goto done;
306 	}
307 
308 	match_remote_ref(have_refs, have, refname);
309 	err = send_fetch_ref(ibuf, want, refname);
310 	if (err)
311 		goto done;
312 
313 	if (chattygot)
314 		fprintf(stderr, "%s: %s will be fetched\n",
315 		    getprogname(), refname);
316 	if (chattygot > 1) {
317 		err = got_object_id_str(&theirs, want);
318 		if (err)
319 			goto done;
320 		err = got_object_id_str(&mine, have);
321 		if (err)
322 			goto done;
323 		fprintf(stderr, "%s: remote: %s\n%s: local:  %s\n",
324 		    getprogname(), theirs, getprogname(), mine);
325 	}
326 done:
327 	free(theirs);
328 	free(mine);
329 	return err;
330 }
331 
332 static const struct got_error *
333 fetch_pack(int fd, int packfd, uint8_t *pack_sha1,
334     struct got_pathlist_head *have_refs, int fetch_all_branches,
335     struct got_pathlist_head *wanted_branches,
336     struct got_pathlist_head *wanted_refs, int list_refs_only,
337     const char *worktree_branch, const char *remote_head,
338     int no_head, struct imsgbuf *ibuf)
339 {
340 	const struct got_error *err = NULL;
341 	char buf[GOT_PKT_MAX];
342 	char hashstr[SHA1_DIGEST_STRING_LENGTH];
343 	struct got_object_id *have, *want;
344 	int is_firstpkt = 1, nref = 0, refsz = 16;
345 	int i, n, nwant = 0, nhave = 0, acked = 0;
346 	off_t packsz = 0, last_reported_packsz = 0;
347 	char *id_str = NULL, *default_id_str = NULL, *refname = NULL;
348 	char *server_capabilities = NULL, *my_capabilities = NULL;
349 	const char *default_branch = NULL;
350 	struct got_pathlist_head symrefs;
351 	struct got_pathlist_entry *pe;
352 	int sent_my_capabilites = 0, have_sidebands = 0;
353 	int found_branch = 0;
354 	struct got_hash ctx;
355 	uint8_t sha1_buf[SHA1_DIGEST_LENGTH];
356 	size_t sha1_buf_len = 0;
357 	ssize_t w;
358 	struct got_ratelimit rl;
359 
360 	TAILQ_INIT(&symrefs);
361 	got_hash_init(&ctx, GOT_HASH_SHA1);
362 	got_ratelimit_init(&rl, 0, 500);
363 
364 	have = malloc(refsz * sizeof(have[0]));
365 	if (have == NULL)
366 		return got_error_from_errno("malloc");
367 	want = malloc(refsz * sizeof(want[0]));
368 	if (want == NULL) {
369 		err = got_error_from_errno("malloc");
370 		goto done;
371 	}
372 	while (1) {
373 		err = got_pkt_readpkt(&n, fd, buf, sizeof(buf), chattygot);
374 		if (err)
375 			goto done;
376 		if (n == 0)
377 			break;
378 		if (n >= 4 && strncmp(buf, "ERR ", 4) == 0) {
379 			err = fetch_error(&buf[4], n - 4);
380 			goto done;
381 		}
382 		free(id_str);
383 		free(refname);
384 		err = got_gitproto_parse_refline(&id_str, &refname,
385 		    &server_capabilities, buf, n);
386 		if (err)
387 			goto done;
388 
389 		if (refsz == nref + 1) {
390 			struct got_object_id *h, *w;
391 
392 			refsz *= 2;
393 			h = reallocarray(have, refsz, sizeof(have[0]));
394 			if (h == NULL) {
395 				err = got_error_from_errno("reallocarray");
396 				goto done;
397 			}
398 			have = h;
399 			w = reallocarray(want, refsz, sizeof(want[0]));
400 			if (w == NULL) {
401 				err = got_error_from_errno("reallocarray");
402 				goto done;
403 			}
404 			want = w;
405 		}
406 
407 		if (is_firstpkt) {
408 			if (chattygot && server_capabilities[0] != '\0')
409 				fprintf(stderr, "%s: server capabilities: %s\n",
410 				    getprogname(), server_capabilities);
411 			err = got_gitproto_match_capabilities(&my_capabilities,
412 			    &symrefs, server_capabilities,
413 			    got_capabilities, nitems(got_capabilities));
414 			if (err)
415 				goto done;
416 			if (chattygot)
417 				fprintf(stderr, "%s: my capabilities:%s\n",
418 				    getprogname(), my_capabilities != NULL ?
419 				    my_capabilities : "");
420 			err = send_fetch_symrefs(ibuf, &symrefs);
421 			if (err)
422 				goto done;
423 			is_firstpkt = 0;
424 			if (!fetch_all_branches) {
425 				TAILQ_FOREACH(pe, &symrefs, entry) {
426 					const char *name = pe->path;
427 					const char *symref_target = pe->data;
428 					if (strcmp(name, GOT_REF_HEAD) != 0)
429 						continue;
430 					default_branch = symref_target;
431 					break;
432 				}
433 			}
434 			if (default_branch)
435 				continue;
436 		}
437 		if (strstr(refname, "^{}")) {
438 			if (chattygot) {
439 				fprintf(stderr, "%s: ignoring %s\n",
440 				    getprogname(), refname);
441 			}
442 			continue;
443 		}
444 		if (default_branch && default_id_str == NULL &&
445 		    strcmp(refname, default_branch) == 0) {
446 			default_id_str = strdup(id_str);
447 			if (default_id_str == NULL) {
448 				err = got_error_from_errno("strdup");
449 				goto done;
450 			}
451 		}
452 
453 		if (list_refs_only || strncmp(refname, "refs/tags/", 10) == 0) {
454 			err = fetch_ref(ibuf, have_refs, &have[nref],
455 			    &want[nref], refname, id_str);
456 			if (err)
457 				goto done;
458 			nref++;
459 		} else if (strncmp(refname, "refs/heads/", 11) == 0) {
460 			if (fetch_all_branches) {
461 				err = fetch_ref(ibuf, have_refs, &have[nref],
462 				    &want[nref], refname, id_str);
463 				if (err)
464 					goto done;
465 				nref++;
466 				found_branch = 1;
467 				continue;
468 			}
469 			TAILQ_FOREACH(pe, wanted_branches, entry) {
470 				if (match_branch(refname, pe->path))
471 					break;
472 			}
473 			if (pe != NULL || (worktree_branch != NULL &&
474 			    match_branch(refname, worktree_branch))) {
475 				err = fetch_ref(ibuf, have_refs, &have[nref],
476 				    &want[nref], refname, id_str);
477 				if (err)
478 					goto done;
479 				nref++;
480 				found_branch = 1;
481 			} else if (chattygot) {
482 				fprintf(stderr, "%s: ignoring %s\n",
483 				    getprogname(), refname);
484 			}
485 		} else {
486 			TAILQ_FOREACH(pe, wanted_refs, entry) {
487 				if (match_wanted_ref(refname, pe->path))
488 					break;
489 			}
490 			if (pe != NULL) {
491 				err = fetch_ref(ibuf, have_refs, &have[nref],
492 				    &want[nref], refname, id_str);
493 				if (err)
494 					goto done;
495 				nref++;
496 			} else if (chattygot) {
497 				fprintf(stderr, "%s: ignoring %s\n",
498 				    getprogname(), refname);
499 			}
500 		}
501 	}
502 
503 	if (list_refs_only)
504 		goto done;
505 
506 	/*
507 	 * If -b was not used and either none of the requested branches
508 	 * (got.conf, worktree) were found or the client already has the
509 	 * remote HEAD symref but its target changed, fetch remote's HEAD.
510 	 */
511 	if (!no_head && default_branch && default_id_str &&
512 	    strncmp(default_branch, "refs/heads/", 11) == 0) {
513 		int remote_head_changed = 0;
514 
515 		if (remote_head) {
516 			if (strcmp(remote_head, default_branch + 11) != 0)
517 				remote_head_changed = 1;
518 		}
519 
520 		if (!found_branch || remote_head_changed) {
521 			err = fetch_ref(ibuf, have_refs, &have[nref],
522 			    &want[nref], default_branch, default_id_str);
523 			if (err)
524 				goto done;
525 			nref++;
526 		}
527 	}
528 
529 	/* Abort if we haven't found anything to fetch. */
530 	if (nref == 0) {
531 		struct got_pathlist_entry *pe;
532 		static char msg[PATH_MAX + 33];
533 
534 		pe = TAILQ_FIRST(wanted_branches);
535 		if (pe) {
536 			snprintf(msg, sizeof(msg),
537 			    "branch \"%s\" not found on server", pe->path);
538 			err = got_error_msg(GOT_ERR_FETCH_NO_BRANCH, msg);
539 			goto done;
540 		}
541 
542 		pe = TAILQ_FIRST(wanted_refs);
543 		if (pe) {
544 			snprintf(msg, sizeof(msg),
545 			    "reference \"%s\" not found on server", pe->path);
546 			err = got_error_msg(GOT_ERR_FETCH_NO_BRANCH, msg);
547 			goto done;
548 		}
549 
550 		err = got_error(GOT_ERR_FETCH_NO_BRANCH);
551 		goto done;
552 	}
553 
554 	for (i = 0; i < nref; i++) {
555 		if (got_object_id_cmp(&have[i], &want[i]) == 0)
556 			continue;
557 		got_sha1_digest_to_str(want[i].sha1, hashstr, sizeof(hashstr));
558 		n = snprintf(buf, sizeof(buf), "want %s%s\n", hashstr,
559 		    sent_my_capabilites || my_capabilities == NULL ?
560 		    "" : my_capabilities);
561 		if (n < 0 || (size_t)n >= sizeof(buf)) {
562 			err = got_error(GOT_ERR_NO_SPACE);
563 			goto done;
564 		}
565 		err = got_pkt_writepkt(fd, buf, n, chattygot);
566 		if (err)
567 			goto done;
568 		sent_my_capabilites = 1;
569 		nwant++;
570 	}
571 	err = got_pkt_flushpkt(fd, chattygot);
572 	if (err)
573 		goto done;
574 
575 	if (nwant == 0)
576 		goto done;
577 
578 	TAILQ_FOREACH(pe, have_refs, entry) {
579 		struct got_object_id *id = pe->data;
580 		got_sha1_digest_to_str(id->sha1, hashstr, sizeof(hashstr));
581 		n = snprintf(buf, sizeof(buf), "have %s\n", hashstr);
582 		if (n < 0 || (size_t)n >= sizeof(buf)) {
583 			err = got_error(GOT_ERR_NO_SPACE);
584 			goto done;
585 		}
586 		err = got_pkt_writepkt(fd, buf, n, chattygot);
587 		if (err)
588 			goto done;
589 		nhave++;
590 	}
591 
592 	n = strlcpy(buf, "done\n", sizeof(buf));
593 	err = got_pkt_writepkt(fd, buf, n, chattygot);
594 	if (err)
595 		goto done;
596 
597 	while (nhave > 0 && !acked) {
598 		struct got_object_id common_id;
599 
600 		/* The server should ACK the object IDs we need. */
601 		err = got_pkt_readpkt(&n, fd, buf, sizeof(buf), chattygot);
602 		if (err)
603 			goto done;
604 		if (n >= 4 && strncmp(buf, "ERR ", 4) == 0) {
605 			err = fetch_error(&buf[4], n - 4);
606 			goto done;
607 		}
608 		if (n >= 4 && strncmp(buf, "NAK\n", 4) == 0) {
609 			/*
610 			 * Server could not find a common ancestor.
611 			 * Perhaps it is an out-of-date mirror, or there
612 			 * is a repository with unrelated history.
613 			 */
614 			break;
615 		}
616 		if (n < 4 + SHA1_DIGEST_STRING_LENGTH ||
617 		    strncmp(buf, "ACK ", 4) != 0) {
618 			err = got_error_msg(GOT_ERR_BAD_PACKET,
619 			    "unexpected message from server");
620 			goto done;
621 		}
622 		if (!got_parse_object_id(&common_id, buf + 4,
623 		    GOT_HASH_SHA1)) {
624 			err = got_error_msg(GOT_ERR_BAD_PACKET,
625 			    "bad object ID in ACK packet from server");
626 			goto done;
627 		}
628 		acked++;
629 	}
630 
631 	if (nhave == 0) {
632 		err = got_pkt_readpkt(&n, fd, buf, sizeof(buf), chattygot);
633 		if (err)
634 			goto done;
635 		if (n != 4 || strncmp(buf, "NAK\n", n) != 0) {
636 			err = got_error_msg(GOT_ERR_BAD_PACKET,
637 			    "unexpected message from server");
638 			goto done;
639 		}
640 	}
641 
642 	if (chattygot)
643 		fprintf(stderr, "%s: fetching...\n", getprogname());
644 
645 	if (my_capabilities != NULL &&
646 	    strstr(my_capabilities, GOT_CAPA_SIDE_BAND_64K) != NULL)
647 		have_sidebands = 1;
648 
649 	while (1) {
650 		ssize_t r = 0;
651 		int datalen = -1;
652 
653 		if (have_sidebands) {
654 			err = got_pkt_readhdr(&datalen, fd, chattygot);
655 			if (err)
656 				goto done;
657 			if (datalen <= 0)
658 				break;
659 
660 			/* Read sideband channel ID (one byte). */
661 			r = read(fd, buf, 1);
662 			if (r == -1) {
663 				err = got_error_from_errno("read");
664 				goto done;
665 			}
666 			if (r != 1) {
667 				err = got_error_msg(GOT_ERR_BAD_PACKET,
668 				    "short packet");
669 				goto done;
670 			}
671 			if (datalen > sizeof(buf) - 5) {
672 				err = got_error_msg(GOT_ERR_BAD_PACKET,
673 				    "bad packet length");
674 				goto done;
675 			}
676 			datalen--; /* sideband ID has been read */
677 			if (buf[0] == GOT_SIDEBAND_PACKFILE_DATA) {
678 				/* Read packfile data. */
679 				err = got_pkt_readn(&r, fd, buf, datalen);
680 				if (err)
681 					goto done;
682 				if (r != datalen) {
683 					err = got_error_msg(GOT_ERR_BAD_PACKET,
684 					    "packet too short");
685 					goto done;
686 				}
687 			} else if (buf[0] == GOT_SIDEBAND_PROGRESS_INFO) {
688 				err = got_pkt_readn(&r, fd, buf, datalen);
689 				if (err)
690 					goto done;
691 				if (r != datalen) {
692 					err = got_error_msg(GOT_ERR_BAD_PACKET,
693 					    "packet too short");
694 					goto done;
695 				}
696 				err = fetch_progress(ibuf, buf, r);
697 				if (err)
698 					goto done;
699 				continue;
700 			} else if (buf[0] == GOT_SIDEBAND_ERROR_INFO) {
701 				err = got_pkt_readn(&r, fd, buf, datalen);
702 				if (err)
703 					goto done;
704 				if (r != datalen) {
705 					err = got_error_msg(GOT_ERR_BAD_PACKET,
706 					    "packet too short");
707 					goto done;
708 				}
709 				err = fetch_error(buf, r);
710 				goto done;
711 			} else if (buf[0] == 'A') {
712 				err = got_pkt_readn(&r, fd, buf, datalen);
713 				if (err)
714 					goto done;
715 				if (r != datalen) {
716 					err = got_error_msg(GOT_ERR_BAD_PACKET,
717 					    "packet too short");
718 					goto done;
719 				}
720 				/*
721 				 * Git server responds with ACK after 'done'
722 				 * even though multi_ack is disabled?!?
723 				 */
724 				buf[r] = '\0';
725 				if (strncmp(buf, "CK ", 3) == 0)
726 					continue; /* ignore */
727 				err = got_error_msg(GOT_ERR_BAD_PACKET,
728 				    "unexpected message from server");
729 				goto done;
730 			} else {
731 				err = got_error_msg(GOT_ERR_BAD_PACKET,
732 				    "unknown side-band received from server");
733 				goto done;
734 			}
735 		} else {
736 			/* No sideband channel. Every byte is packfile data. */
737 			err = got_pkt_readn(&r, fd, buf, sizeof buf);
738 			if (err)
739 				goto done;
740 			if (r <= 0)
741 				break;
742 		}
743 
744 		/*
745 		 * An expected SHA1 checksum sits at the end of the pack file.
746 		 * Since we don't know the file size ahead of time we have to
747 		 * keep SHA1_DIGEST_LENGTH bytes buffered and avoid mixing
748 		 * those bytes into our SHA1 checksum computation until we
749 		 * know for sure that additional pack file data bytes follow.
750 		 *
751 		 * We can assume r > 0 since otherwise the loop would exit.
752 		 */
753 		if (r < SHA1_DIGEST_LENGTH) {
754 			if (sha1_buf_len < SHA1_DIGEST_LENGTH) {
755 				/*
756 				 * If there's enough buffered + read data to
757 				 * fill up the buffer then shift a sufficient
758 				 * amount of bytes out at the front to make
759 				 * room, mixing those bytes into the checksum.
760 				 */
761 				if (sha1_buf_len > 0 &&
762 				    sha1_buf_len + r > SHA1_DIGEST_LENGTH) {
763 					size_t nshift = MIN(sha1_buf_len + r -
764 					    SHA1_DIGEST_LENGTH, sha1_buf_len);
765 					got_hash_update(&ctx, sha1_buf,
766 					    nshift);
767 					memmove(sha1_buf, sha1_buf + nshift,
768 					    sha1_buf_len - nshift);
769 					sha1_buf_len -= nshift;
770 				}
771 
772 				/* Buffer potential checksum bytes. */
773 				memcpy(sha1_buf + sha1_buf_len, buf, r);
774 				sha1_buf_len += r;
775 			} else {
776 				/*
777 				 * Mix in previously buffered bytes which
778 				 * are not part of the checksum after all.
779 				 */
780 				got_hash_update(&ctx, sha1_buf, r);
781 
782 				/* Update potential checksum buffer. */
783 				memmove(sha1_buf, sha1_buf + r,
784 				    sha1_buf_len - r);
785 				memcpy(sha1_buf + sha1_buf_len - r, buf, r);
786 			}
787 		} else {
788 			/* Mix in any previously buffered bytes. */
789 			got_hash_update(&ctx, sha1_buf, sha1_buf_len);
790 
791 			/* Mix in bytes read minus potential checksum bytes. */
792 			got_hash_update(&ctx, buf, r - SHA1_DIGEST_LENGTH);
793 
794 			/* Buffer potential checksum bytes. */
795 			memcpy(sha1_buf, buf + r - SHA1_DIGEST_LENGTH,
796 			    SHA1_DIGEST_LENGTH);
797 			sha1_buf_len = SHA1_DIGEST_LENGTH;
798 		}
799 
800 		/* Write packfile data to temporary pack file. */
801 		w = write(packfd, buf, r);
802 		if (w == -1) {
803 			err = got_error_from_errno("write");
804 			goto done;
805 		}
806 		if (w != r) {
807 			err = got_error(GOT_ERR_IO);
808 			goto done;
809 		}
810 		packsz += w;
811 
812 		/* Don't send too many progress privsep messages. */
813 		if (packsz > last_reported_packsz + 1024) {
814 			err = send_fetch_download_progress(ibuf, packsz, &rl);
815 			if (err)
816 				goto done;
817 			last_reported_packsz = packsz;
818 		}
819 	}
820 	err = send_fetch_download_progress(ibuf, packsz, NULL);
821 	if (err)
822 		goto done;
823 
824 	got_hash_final(&ctx, pack_sha1);
825 	if (sha1_buf_len != SHA1_DIGEST_LENGTH ||
826 	    memcmp(pack_sha1, sha1_buf, sha1_buf_len) != 0) {
827 		err = got_error_msg(GOT_ERR_BAD_PACKFILE,
828 		    "pack file checksum mismatch");
829 	}
830 done:
831 	got_pathlist_free(&symrefs, GOT_PATHLIST_FREE_ALL);
832 	free(have);
833 	free(want);
834 	free(id_str);
835 	free(default_id_str);
836 	free(refname);
837 	free(server_capabilities);
838 	return err;
839 }
840 
841 
842 int
843 main(int argc, char **argv)
844 {
845 	const struct got_error *err = NULL;
846 	int fetchfd = -1, packfd = -1;
847 	uint8_t pack_sha1[SHA1_DIGEST_LENGTH];
848 	struct imsgbuf ibuf;
849 	struct imsg imsg;
850 	struct got_pathlist_head have_refs;
851 	struct got_pathlist_head wanted_branches;
852 	struct got_pathlist_head wanted_refs;
853 	struct got_imsg_fetch_request fetch_req;
854 	struct got_imsg_fetch_have_ref href;
855 	struct got_imsg_fetch_wanted_branch wbranch;
856 	struct got_imsg_fetch_wanted_ref wref;
857 	size_t datalen, i;
858 	char *remote_head = NULL, *worktree_branch = NULL;
859 #if 0
860 	static int attached;
861 	while (!attached)
862 		sleep (1);
863 #endif
864 
865 	TAILQ_INIT(&have_refs);
866 	TAILQ_INIT(&wanted_branches);
867 	TAILQ_INIT(&wanted_refs);
868 
869 	imsg_init(&ibuf, GOT_IMSG_FD_CHILD);
870 #ifndef PROFILE
871 	/* revoke access to most system calls */
872 	if (pledge("stdio recvfd", NULL) == -1) {
873 		err = got_error_from_errno("pledge");
874 		got_privsep_send_error(&ibuf, err);
875 		return 1;
876 	}
877 #endif
878 	err = got_privsep_recv_imsg(&imsg, &ibuf, 0);
879 	if (err) {
880 		if (err->code == GOT_ERR_PRIVSEP_PIPE)
881 			err = NULL;
882 		goto done;
883 	}
884 	if (imsg.hdr.type == GOT_IMSG_STOP)
885 		goto done;
886 	if (imsg.hdr.type != GOT_IMSG_FETCH_REQUEST) {
887 		err = got_error(GOT_ERR_PRIVSEP_MSG);
888 		goto done;
889 	}
890 	datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
891 	if (datalen < sizeof(fetch_req)) {
892 		err = got_error(GOT_ERR_PRIVSEP_LEN);
893 		goto done;
894 	}
895 	memcpy(&fetch_req, imsg.data, sizeof(fetch_req));
896 	fetchfd = imsg.fd;
897 
898 	if (datalen != sizeof(fetch_req) +
899 	    fetch_req.worktree_branch_len + fetch_req.remote_head_len) {
900 		err = got_error(GOT_ERR_PRIVSEP_LEN);
901 		goto done;
902 	}
903 
904 	if (fetch_req.worktree_branch_len != 0) {
905 		worktree_branch = strndup(imsg.data +
906 		    sizeof(fetch_req), fetch_req.worktree_branch_len);
907 		if (worktree_branch == NULL) {
908 			err = got_error_from_errno("strndup");
909 			goto done;
910 		}
911 	}
912 
913 	if (fetch_req.remote_head_len != 0) {
914 		remote_head = strndup(imsg.data + sizeof(fetch_req) +
915 		    fetch_req.worktree_branch_len, fetch_req.remote_head_len);
916 		if (remote_head == NULL) {
917 			err = got_error_from_errno("strndup");
918 			goto done;
919 		}
920 	}
921 
922 	imsg_free(&imsg);
923 
924 	if (fetch_req.verbosity > 0)
925 		chattygot += fetch_req.verbosity;
926 
927 	for (i = 0; i < fetch_req.n_have_refs; i++) {
928 		struct got_object_id *id;
929 		char *refname;
930 
931 		err = got_privsep_recv_imsg(&imsg, &ibuf, 0);
932 		if (err) {
933 			if (err->code == GOT_ERR_PRIVSEP_PIPE)
934 				err = NULL;
935 			goto done;
936 		}
937 		if (imsg.hdr.type == GOT_IMSG_STOP)
938 			goto done;
939 		if (imsg.hdr.type != GOT_IMSG_FETCH_HAVE_REF) {
940 			err = got_error(GOT_ERR_PRIVSEP_MSG);
941 			goto done;
942 		}
943 		datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
944 		if (datalen < sizeof(href)) {
945 			err = got_error(GOT_ERR_PRIVSEP_LEN);
946 			goto done;
947 		}
948 		memcpy(&href, imsg.data, sizeof(href));
949 		if (datalen - sizeof(href) < href.name_len) {
950 			err = got_error(GOT_ERR_PRIVSEP_LEN);
951 			goto done;
952 		}
953 		refname = strndup(imsg.data + sizeof(href), href.name_len);
954 		if (refname == NULL) {
955 			err = got_error_from_errno("strndup");
956 			goto done;
957 		}
958 
959 		id = malloc(sizeof(*id));
960 		if (id == NULL) {
961 			free(refname);
962 			err = got_error_from_errno("malloc");
963 			goto done;
964 		}
965 		memcpy(id, &href.id, sizeof(*id));
966 		err = got_pathlist_append(&have_refs, refname, id);
967 		if (err) {
968 			free(refname);
969 			free(id);
970 			goto done;
971 		}
972 
973 		imsg_free(&imsg);
974 	}
975 
976 	for (i = 0; i < fetch_req.n_wanted_branches; i++) {
977 		char *refname;
978 
979 		err = got_privsep_recv_imsg(&imsg, &ibuf, 0);
980 		if (err) {
981 			if (err->code == GOT_ERR_PRIVSEP_PIPE)
982 				err = NULL;
983 			goto done;
984 		}
985 		if (imsg.hdr.type == GOT_IMSG_STOP)
986 			goto done;
987 		if (imsg.hdr.type != GOT_IMSG_FETCH_WANTED_BRANCH) {
988 			err = got_error(GOT_ERR_PRIVSEP_MSG);
989 			goto done;
990 		}
991 		datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
992 		if (datalen < sizeof(wbranch)) {
993 			err = got_error(GOT_ERR_PRIVSEP_LEN);
994 			goto done;
995 		}
996 		memcpy(&wbranch, imsg.data, sizeof(wbranch));
997 		if (datalen - sizeof(wbranch) < wbranch.name_len) {
998 			err = got_error(GOT_ERR_PRIVSEP_LEN);
999 			goto done;
1000 		}
1001 		refname = strndup(imsg.data + sizeof(wbranch),
1002 		    wbranch.name_len);
1003 		if (refname == NULL) {
1004 			err = got_error_from_errno("strndup");
1005 			goto done;
1006 		}
1007 
1008 		err = got_pathlist_append(&wanted_branches, refname, NULL);
1009 		if (err) {
1010 			free(refname);
1011 			goto done;
1012 		}
1013 
1014 		imsg_free(&imsg);
1015 	}
1016 
1017 	for (i = 0; i < fetch_req.n_wanted_refs; i++) {
1018 		char *refname;
1019 
1020 		err = got_privsep_recv_imsg(&imsg, &ibuf, 0);
1021 		if (err) {
1022 			if (err->code == GOT_ERR_PRIVSEP_PIPE)
1023 				err = NULL;
1024 			goto done;
1025 		}
1026 		if (imsg.hdr.type == GOT_IMSG_STOP)
1027 			goto done;
1028 		if (imsg.hdr.type != GOT_IMSG_FETCH_WANTED_REF) {
1029 			err = got_error(GOT_ERR_PRIVSEP_MSG);
1030 			goto done;
1031 		}
1032 		datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
1033 		if (datalen < sizeof(wref)) {
1034 			err = got_error(GOT_ERR_PRIVSEP_LEN);
1035 			goto done;
1036 		}
1037 		memcpy(&wref, imsg.data, sizeof(wref));
1038 		if (datalen - sizeof(wref) < wref.name_len) {
1039 			err = got_error(GOT_ERR_PRIVSEP_LEN);
1040 			goto done;
1041 		}
1042 		refname = strndup(imsg.data + sizeof(wref), wref.name_len);
1043 		if (refname == NULL) {
1044 			err = got_error_from_errno("strndup");
1045 			goto done;
1046 		}
1047 
1048 		err = got_pathlist_append(&wanted_refs, refname, NULL);
1049 		if (err) {
1050 			free(refname);
1051 			goto done;
1052 		}
1053 
1054 		imsg_free(&imsg);
1055 	}
1056 
1057 	err = got_privsep_recv_imsg(&imsg, &ibuf, 0);
1058 	if (err) {
1059 		if (err->code == GOT_ERR_PRIVSEP_PIPE)
1060 			err = NULL;
1061 		goto done;
1062 	}
1063 	if (imsg.hdr.type == GOT_IMSG_STOP)
1064 		goto done;
1065 	if (imsg.hdr.type != GOT_IMSG_FETCH_OUTFD) {
1066 		err = got_error(GOT_ERR_PRIVSEP_MSG);
1067 		goto done;
1068 	}
1069 	if (imsg.hdr.len - IMSG_HEADER_SIZE != 0) {
1070 		err = got_error(GOT_ERR_PRIVSEP_LEN);
1071 		goto done;
1072 	}
1073 	packfd = imsg.fd;
1074 
1075 	err = fetch_pack(fetchfd, packfd, pack_sha1, &have_refs,
1076 	    fetch_req.fetch_all_branches, &wanted_branches,
1077 	    &wanted_refs, fetch_req.list_refs_only,
1078 	    worktree_branch, remote_head, fetch_req.no_head, &ibuf);
1079 done:
1080 	free(worktree_branch);
1081 	free(remote_head);
1082 	got_pathlist_free(&have_refs, GOT_PATHLIST_FREE_ALL);
1083 	got_pathlist_free(&wanted_branches, GOT_PATHLIST_FREE_PATH);
1084 	if (fetchfd != -1 && close(fetchfd) == -1 && err == NULL)
1085 		err = got_error_from_errno("close");
1086 	if (packfd != -1 && close(packfd) == -1 && err == NULL)
1087 		err = got_error_from_errno("close");
1088 	if (err != NULL)
1089 		got_privsep_send_error(&ibuf, err);
1090 	else
1091 		err = send_fetch_done(&ibuf, pack_sha1);
1092 	if (err != NULL) {
1093 		fprintf(stderr, "%s: %s\n", getprogname(), err->msg);
1094 		got_privsep_send_error(&ibuf, err);
1095 	}
1096 
1097 	exit(0);
1098 }