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