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