aboutsummaryrefslogtreecommitdiff
path: root/src/fs/fs_download.c
blob: 80758ebc72dc3b16b69177d67b19b5f7ee0c49d6 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
/*
     This file is part of GNUnet.
     (C) 2001, 2002, 2003, 2004, 2005, 2006, 2008, 2009, 2010 Christian Grothoff (and other contributing authors)

     GNUnet is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published
     by the Free Software Foundation; either version 3, or (at your
     option) any later version.

     GNUnet is distributed in the hope that it will be useful, but
     WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     General Public License for more details.

     You should have received a copy of the GNU General Public License
     along with GNUnet; see the file COPYING.  If not, write to the
     Free Software Foundation, Inc., 59 Temple Place - Suite 330,
     Boston, MA 02111-1307, USA.
*/
/**
 * @file fs/fs_download.c
 * @brief download methods
 * @author Christian Grothoff
 *
 * TODO:
 * - different priority for scheduling probe downloads?
 * - check if iblocks can be computed from existing blocks (can wait, hard)
 */
#include "platform.h"
#include "gnunet_constants.h"
#include "gnunet_fs_service.h"
#include "fs.h"
#include "fs_tree.h"

#define DEBUG_DOWNLOAD GNUNET_NO

/**
 * Determine if the given download (options and meta data) should cause
 * use to try to do a recursive download.
 */
static int
is_recursive_download (struct GNUNET_FS_DownloadContext *dc)
{
  return  (0 != (dc->options & GNUNET_FS_DOWNLOAD_OPTION_RECURSIVE)) &&
    ( (GNUNET_YES == GNUNET_FS_meta_data_test_for_directory (dc->meta)) ||
      ( (dc->meta == NULL) &&
	( (NULL == dc->filename) ||	       
	  ( (strlen (dc->filename) >= strlen (GNUNET_FS_DIRECTORY_EXT)) &&
	    (NULL !=
	     strstr (dc->filename + strlen(dc->filename) - strlen(GNUNET_FS_DIRECTORY_EXT),
		     GNUNET_FS_DIRECTORY_EXT)) ) ) ) );		     
}


/**
 * We're storing the IBLOCKS after the DBLOCKS on disk (so that we
 * only have to truncate the file once we're done).
 *
 * Given the offset of a block (with respect to the DBLOCKS) and its
 * depth, return the offset where we would store this block in the
 * file.
 * 
 * @param fsize overall file size
 * @param off offset of the block in the file
 * @param depth depth of the block in the tree
 * @param treedepth maximum depth of the tree
 * @return off for DBLOCKS (depth == treedepth),
 *         otherwise an offset past the end
 *         of the file that does not overlap
 *         with the range for any other block
 */
static uint64_t
compute_disk_offset (uint64_t fsize,
		     uint64_t off,
		     unsigned int depth,
		     unsigned int treedepth)
{
  unsigned int i;
  uint64_t lsize; /* what is the size of all IBlocks for depth "i"? */
  uint64_t loff; /* where do IBlocks for depth "i" start? */
  unsigned int ioff; /* which IBlock corresponds to "off" at depth "i"? */
  
  if (depth == treedepth)
    return off;
  /* first IBlocks start at the end of file, rounded up
     to full DBLOCK_SIZE */
  loff = ((fsize + DBLOCK_SIZE - 1) / DBLOCK_SIZE) * DBLOCK_SIZE;
  lsize = ( (fsize + DBLOCK_SIZE-1) / DBLOCK_SIZE) * sizeof (struct ContentHashKey);
  GNUNET_assert (0 == (off % DBLOCK_SIZE));
  ioff = (off / DBLOCK_SIZE);
  for (i=treedepth-1;i>depth;i--)
    {
      loff += lsize;
      lsize = (lsize + CHK_PER_INODE - 1) / CHK_PER_INODE;
      GNUNET_assert (lsize > 0);
      GNUNET_assert (0 == (ioff % CHK_PER_INODE));
      ioff /= CHK_PER_INODE;
    }
  return loff + ioff * sizeof (struct ContentHashKey);
}


/**
 * Given a file of the specified treedepth and a block at the given
 * offset and depth, calculate the offset for the CHK at the given
 * index.
 *
 * @param offset the offset of the first
 *        DBLOCK in the subtree of the 
 *        identified IBLOCK
 * @param depth the depth of the IBLOCK in the tree
 * @param treedepth overall depth of the tree
 * @param k which CHK in the IBLOCK are we 
 *        talking about
 * @return offset if k=0, otherwise an appropriately
 *         larger value (i.e., if depth = treedepth-1,
 *         the returned value should be offset+DBLOCK_SIZE)
 */
static uint64_t
compute_dblock_offset (uint64_t offset,
		       unsigned int depth,
		       unsigned int treedepth,
		       unsigned int k)
{
  unsigned int i;
  uint64_t lsize; /* what is the size of the sum of all DBlocks 
		     that a CHK at depth i corresponds to? */

  if (depth == treedepth)
    return offset;
  lsize = DBLOCK_SIZE;
  for (i=treedepth-1;i>depth;i--)
    lsize *= CHK_PER_INODE;
  return offset + k * lsize;
}


/**
 * Fill in all of the generic fields for a download event and call the
 * callback.
 *
 * @param pi structure to fill in
 * @param dc overall download context
 */
void
GNUNET_FS_download_make_status_ (struct GNUNET_FS_ProgressInfo *pi,
				 struct GNUNET_FS_DownloadContext *dc)
{
  pi->value.download.dc = dc;
  pi->value.download.cctx
    = dc->client_info;
  pi->value.download.pctx
    = (dc->parent == NULL) ? NULL : dc->parent->client_info;
  pi->value.download.sctx
    = (dc->search == NULL) ? NULL : dc->search->client_info;
  pi->value.download.uri 
    = dc->uri;
  pi->value.download.filename
    = dc->filename;
  pi->value.download.size
    = dc->length;
  pi->value.download.duration
    = GNUNET_TIME_absolute_get_duration (dc->start_time);
  pi->value.download.completed
    = dc->completed;
  pi->value.download.anonymity
    = dc->anonymity;
  pi->value.download.eta
    = GNUNET_TIME_calculate_eta (dc->start_time,
				 dc->completed,
				 dc->length);
  pi->value.download.is_active = (dc->client == NULL) ? GNUNET_NO : GNUNET_YES;
  if (0 == (dc->options & GNUNET_FS_DOWNLOAD_IS_PROBE))
    dc->client_info = dc->h->upcb (dc->h->upcb_cls,
				   pi);
  else
    dc->client_info = GNUNET_FS_search_probe_progress_ (NULL,
							pi);
}

/**
 * We're ready to transmit a search request to the
 * file-sharing service.  Do it.  If there is 
 * more than one request pending, try to send 
 * multiple or request another transmission.
 *
 * @param cls closure
 * @param size number of bytes available in buf
 * @param buf where the callee should write the message
 * @return number of bytes written to buf
 */
static size_t
transmit_download_request (void *cls,
			   size_t size, 
			   void *buf);


/**
 * Closure for iterator processing results.
 */
struct ProcessResultClosure
{
  
  /**
   * Hash of data.
   */
  GNUNET_HashCode query;

  /**
   * Data found in P2P network.
   */ 
  const void *data;

  /**
   * Our download context.
   */
  struct GNUNET_FS_DownloadContext *dc;
		
  /**
   * Number of bytes in data.
   */
  size_t size;

  /**
   * Type of data.
   */
  enum GNUNET_BLOCK_Type type;

  /**
   * Flag to indicate if this block should be stored on disk.
   */
  int do_store;
  
};


/**
 * Iterator over entries in the pending requests in the 'active' map for the
 * reply that we just got.
 *
 * @param cls closure (our 'struct ProcessResultClosure')
 * @param key query for the given value / request
 * @param value value in the hash map (a 'struct DownloadRequest')
 * @return GNUNET_YES (we should continue to iterate); unless serious error
 */
static int
process_result_with_request (void *cls,
			     const GNUNET_HashCode * key,
			     void *value);


/**
 * We've found a matching block without downloading it.
 * Encrypt it and pass it to our "receive" function as
 * if we had received it from the network.
 * 
 * @param dc download in question
 * @param chk request this relates to
 * @param sm request details
 * @param block plaintext data matching request
 * @param len number of bytes in block
 * @param depth depth of the block
 * @param do_store should we still store the block on disk?
 * @return GNUNET_OK on success
 */
static int
encrypt_existing_match (struct GNUNET_FS_DownloadContext *dc,
			const struct ContentHashKey *chk,
			struct DownloadRequest *sm,
			const char * block,		       
			size_t len,
			int depth,
			int do_store)
{
  struct ProcessResultClosure prc;
  char enc[len];
  struct GNUNET_CRYPTO_AesSessionKey sk;
  struct GNUNET_CRYPTO_AesInitializationVector iv;
  GNUNET_HashCode query;
  
  GNUNET_CRYPTO_hash_to_aes_key (&chk->key, &sk, &iv);
  if (-1 == GNUNET_CRYPTO_aes_encrypt (block, len,
				       &sk,
				       &iv,
				       enc))
    {
      GNUNET_break (0);
      return GNUNET_SYSERR;
    }
  GNUNET_CRYPTO_hash (enc, len, &query);
  if (0 != memcmp (&query,
		   &chk->query,
		   sizeof (GNUNET_HashCode)))
    {
      GNUNET_break_op (0);
      return GNUNET_SYSERR;
    }
#if DEBUG_DOWNLOAD
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
	      "Matching block already present, no need for download!\n");
#endif
  /* already got it! */
  prc.dc = dc;
  prc.data = enc;
  prc.size = len;
  prc.type = (dc->treedepth == depth) 
    ? GNUNET_BLOCK_TYPE_DBLOCK 
    : GNUNET_BLOCK_TYPE_IBLOCK;
  prc.query = chk->query;
  prc.do_store = do_store;
  process_result_with_request (&prc,
			       &chk->key,
			       sm);
  return GNUNET_OK;
}


/**
 * Closure for match_full_data.
 */
struct MatchDataContext 
{
  /**
   * CHK we are looking for.
   */
  const struct ContentHashKey *chk;

  /**
   * Download we're processing.
   */
  struct GNUNET_FS_DownloadContext *dc;

  /**
   * Request details.
   */
  struct DownloadRequest *sm;

  /**
   * Overall offset in the file.
   */
  uint64_t offset;

  /**
   * Desired length of the block.
   */
  size_t len;

  /**
   * Flag set to GNUNET_YES on success.
   */
  int done;
};

/**
 * Type of a function that libextractor calls for each
 * meta data item found.
 *
 * @param cls closure (user-defined)
 * @param plugin_name name of the plugin that produced this value;
 *        special values can be used (i.e. '<zlib>' for zlib being
 *        used in the main libextractor library and yielding
 *        meta data).
 * @param type libextractor-type describing the meta data
 * @param format basic format information about data 
 * @param data_mime_type mime-type of data (not of the original file);
 *        can be NULL (if mime-type is not known)
 * @param data actual meta-data found
 * @param data_len number of bytes in data
 * @return 0 to continue extracting, 1 to abort
 */ 
static int
match_full_data (void *cls,
		 const char *plugin_name,
		 enum EXTRACTOR_MetaType type,
		 enum EXTRACTOR_MetaFormat format,
		 const char *data_mime_type,
		 const char *data,
		 size_t data_len)
{
  struct MatchDataContext *mdc = cls;
  GNUNET_HashCode key;

  if (type == EXTRACTOR_METATYPE_GNUNET_FULL_DATA) 
    {
      if ( (mdc->offset > data_len) ||
	   (mdc->offset + mdc->len > data_len) )
	return 1;
      GNUNET_CRYPTO_hash (&data[mdc->offset],
			  mdc->len,
			  &key);
      if (0 != memcmp (&key,
		       &mdc->chk->key,
		       sizeof (GNUNET_HashCode)))
	{
	  GNUNET_break_op (0);
	  return 1;
	}
      /* match found! */
      if (GNUNET_OK !=
	  encrypt_existing_match (mdc->dc,
				  mdc->chk,
				  mdc->sm,
				  &data[mdc->offset],
				  mdc->len,
				  0,
				  GNUNET_YES))
	{
	  GNUNET_break_op (0);
	  return 1;
	}
      mdc->done = GNUNET_YES;
      return 1;
    }
  return 0;
}


/**
 * Schedule the download of the specified block in the tree.
 *
 * @param dc overall download this block belongs to
 * @param chk content-hash-key of the block
 * @param offset offset of the block in the file
 *         (for IBlocks, the offset is the lowest
 *          offset of any DBlock in the subtree under
 *          the IBlock)
 * @param depth depth of the block, 0 is the root of the tree
 */
static void
schedule_block_download (struct GNUNET_FS_DownloadContext *dc,
			 const struct ContentHashKey *chk,
			 uint64_t offset,
			 unsigned int depth)
{
  struct DownloadRequest *sm;
  uint64_t total;
  uint64_t off;
  size_t len;
  char block[DBLOCK_SIZE];
  GNUNET_HashCode key;
  struct MatchDataContext mdc;
  struct GNUNET_DISK_FileHandle *fh;

  total = GNUNET_ntohll (dc->uri->data.chk.file_length);
  len = GNUNET_FS_tree_calculate_block_size (total,
					     dc->treedepth,
					     offset,
					     depth);
  off = compute_disk_offset (total,
			     offset,
			     depth,
			     dc->treedepth);
  sm = GNUNET_malloc (sizeof (struct DownloadRequest));
  sm->chk = *chk;
  sm->offset = offset;
  sm->depth = depth;
  sm->is_pending = GNUNET_YES;
  sm->next = dc->pending;
  dc->pending = sm;
  GNUNET_CONTAINER_multihashmap_put (dc->active,
				     &chk->query,
				     sm,
				     GNUNET_CONTAINER_MULTIHASHMAPOPTION_MULTIPLE);
  if ( (dc->tried_full_data == GNUNET_NO) &&
       (depth == 0) )
    {      
      mdc.dc = dc;
      mdc.sm = sm;
      mdc.chk = chk;
      mdc.offset = offset;
      mdc.len = len;
      mdc.done = GNUNET_NO;
      GNUNET_CONTAINER_meta_data_iterate (dc->meta,
					  &match_full_data,
					  &mdc);
      if (mdc.done == GNUNET_YES)
	return;
      dc->tried_full_data = GNUNET_YES; 
    }
#if DEBUG_DOWNLOAD
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
	      "Scheduling download at offset %llu and depth %u for `%s'\n",
	      (unsigned long long) offset,
	      depth,
	      GNUNET_h2s (&chk->query));
#endif
  fh = NULL;
  if ( (dc->old_file_size > off) &&
       (dc->filename != NULL) )    
    fh = GNUNET_DISK_file_open (dc->filename,
				GNUNET_DISK_OPEN_READ,
				GNUNET_DISK_PERM_NONE);    
  if ( (fh != NULL) &&
       (off  == 
	GNUNET_DISK_file_seek (fh,
			       off,
			       GNUNET_DISK_SEEK_SET) ) &&
       (len == 
	GNUNET_DISK_file_read (fh,
			       block,
			       len)) )
    {
      GNUNET_CRYPTO_hash (block, len, &key);
      if ( (0 == memcmp (&key,
			 &chk->key,
			 sizeof (GNUNET_HashCode))) &&
	   (GNUNET_OK ==
	    encrypt_existing_match (dc,
				    chk,
				    sm,
				    block,
				    len,
				    depth,
				    GNUNET_NO)) )
	{
	  GNUNET_break (GNUNET_OK == GNUNET_DISK_file_close (fh));
	  return;
	}
    }
  if (fh != NULL)
    GNUNET_break (GNUNET_OK == GNUNET_DISK_file_close (fh));
  if (depth < dc->treedepth)
    {
      // FIXME: try if we could
      // reconstitute this IBLOCK
      // from the existing blocks on disk (can wait)
      // (read block(s), encode, compare with
      // query; if matches, simply return)
    }

  if ( (dc->th == NULL) &&
       (dc->client != NULL) )
    {
#if DEBUG_DOWNLOAD
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
		  "Asking for transmission to FS service\n");
#endif
      dc->th = GNUNET_CLIENT_notify_transmit_ready (dc->client,
						    sizeof (struct SearchMessage),
						    GNUNET_CONSTANTS_SERVICE_TIMEOUT,
						    GNUNET_NO,
						    &transmit_download_request,
						    dc);
    }
  else
    {
#if DEBUG_DOWNLOAD
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
		  "Transmission request not issued (%p %p)\n",
		  dc->th, 
		  dc->client);
#endif

    }

}



/**
 * Suggest a filename based on given metadata.
 * 
 * @param md given meta data
 * @return NULL if meta data is useless for suggesting a filename
 */
char *
GNUNET_FS_meta_data_suggest_filename (const struct GNUNET_CONTAINER_MetaData *md)
{
  static const char *mimeMap[][2] = {
    {"application/bz2", ".bz2"},
    {"application/gnunet-directory", ".gnd"},
    {"application/java", ".class"},
    {"application/msword", ".doc"},
    {"application/ogg", ".ogg"},
    {"application/pdf", ".pdf"},
    {"application/pgp-keys", ".key"},
    {"application/pgp-signature", ".pgp"},
    {"application/postscript", ".ps"},
    {"application/rar", ".rar"},
    {"application/rtf", ".rtf"},
    {"application/xml", ".xml"},
    {"application/x-debian-package", ".deb"},
    {"application/x-dvi", ".dvi"},
    {"applixation/x-flac", ".flac"},
    {"applixation/x-gzip", ".gz"},
    {"application/x-java-archive", ".jar"},
    {"application/x-java-vm", ".class"},
    {"application/x-python-code", ".pyc"},
    {"application/x-redhat-package-manager", ".rpm"},
    {"application/x-rpm", ".rpm"},
    {"application/x-tar", ".tar"},
    {"application/x-tex-pk", ".pk"},
    {"application/x-texinfo", ".texinfo"},
    {"application/x-xcf", ".xcf"},
    {"application/x-xfig", ".xfig"},
    {"application/zip", ".zip"},
    
    {"audio/midi", ".midi"},
    {"audio/mpeg", ".mp3"},
    {"audio/real", ".rm"},
    {"audio/x-wav", ".wav"},
    
    {"image/gif", ".gif"},
    {"image/jpeg", ".jpg"},
    {"image/pcx", ".pcx"},
    {"image/png", ".png"},
    {"image/tiff", ".tiff"},
    {"image/x-ms-bmp", ".bmp"},
    {"image/x-xpixmap", ".xpm"},
    
    {"text/css", ".css"},
    {"text/html", ".html"},
    {"text/plain", ".txt"},
    {"text/rtf", ".rtf"},
    {"text/x-c++hdr", ".h++"},
    {"text/x-c++src", ".c++"},
    {"text/x-chdr", ".h"},
    {"text/x-csrc", ".c"},
    {"text/x-java", ".java"},
    {"text/x-moc", ".moc"},
    {"text/x-pascal", ".pas"},
    {"text/x-perl", ".pl"},
    {"text/x-python", ".py"},
    {"text/x-tex", ".tex"},
    
    {"video/avi", ".avi"},
    {"video/mpeg", ".mpeg"},
    {"video/quicktime", ".qt"},
    {"video/real", ".rm"},
    {"video/x-msvideo", ".avi"},
    {NULL, NULL},
  };
  char *ret;
  unsigned int i;
  char *mime;
  char *base;
  const char *ext;

  ret = GNUNET_CONTAINER_meta_data_get_by_type (md,
						EXTRACTOR_METATYPE_FILENAME);
  if (ret != NULL)
    return ret;  
  ext = NULL;
  mime = GNUNET_CONTAINER_meta_data_get_by_type (md,
						 EXTRACTOR_METATYPE_MIMETYPE);
  if (mime != NULL)
    {
      i = 0;
      while ( (mimeMap[i][0] != NULL) && 
	      (0 != strcmp (mime, mimeMap[i][0])))
        i++;
      if (mimeMap[i][1] == NULL)
        GNUNET_log (GNUNET_ERROR_TYPE_DEBUG | 
		    GNUNET_ERROR_TYPE_BULK,
		    _("Did not find mime type `%s' in extension list.\n"),
		    mime);
      else
	ext = mimeMap[i][1];
      GNUNET_free (mime);
    }
  base = GNUNET_CONTAINER_meta_data_get_first_by_types (md,
							EXTRACTOR_METATYPE_TITLE,
							EXTRACTOR_METATYPE_BOOK_TITLE,
							EXTRACTOR_METATYPE_ORIGINAL_TITLE,
							EXTRACTOR_METATYPE_PACKAGE_NAME,
							EXTRACTOR_METATYPE_URL,
							EXTRACTOR_METATYPE_URI, 
							EXTRACTOR_METATYPE_DESCRIPTION,
							EXTRACTOR_METATYPE_ISRC,
							EXTRACTOR_METATYPE_JOURNAL_NAME,
							EXTRACTOR_METATYPE_AUTHOR_NAME,
							EXTRACTOR_METATYPE_SUBJECT,
							EXTRACTOR_METATYPE_ALBUM,
							EXTRACTOR_METATYPE_ARTIST,
							EXTRACTOR_METATYPE_KEYWORDS,
							EXTRACTOR_METATYPE_COMMENT,
							EXTRACTOR_METATYPE_UNKNOWN,
							-1);
  if ( (base == NULL) &&
       (ext == NULL) )
    return NULL;
  if (base == NULL)
    return GNUNET_strdup (ext);
  if (ext == NULL)
    return base;
  GNUNET_asprintf (&ret,
		   "%s%s",
		   base,
		   ext);
  GNUNET_free (base);
  return ret;
}


/**
 * We've lost our connection with the FS service.
 * Re-establish it and re-transmit all of our
 * pending requests.
 *
 * @param dc download context that is having trouble
 */
static void
try_reconnect (struct GNUNET_FS_DownloadContext *dc);


/**
 * We found an entry in a directory.  Check if the respective child
 * already exists and if not create the respective child download.
 *
 * @param cls the parent download
 * @param filename name of the file in the directory
 * @param uri URI of the file (CHK or LOC)
 * @param meta meta data of the file
 * @param length number of bytes in data
 * @param data contents of the file (or NULL if they were not inlined)
 */
static void 
trigger_recursive_download (void *cls,
			    const char *filename,
			    const struct GNUNET_FS_Uri *uri,
			    const struct GNUNET_CONTAINER_MetaData *meta,
			    size_t length,
			    const void *data);


/**
 * We're done downloading a directory.  Open the file and
 * trigger all of the (remaining) child downloads.
 *
 * @param dc context of download that just completed
 */
static void
full_recursive_download (struct GNUNET_FS_DownloadContext *dc)
{
  size_t size;
  uint64_t size64;
  void *data;
  struct GNUNET_DISK_FileHandle *h;
  struct GNUNET_DISK_MapHandle *m;
  
  size64 = GNUNET_FS_uri_chk_get_file_size (dc->uri);
  size = (size_t) size64;
  if (size64 != (uint64_t) size)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
		  _("Recursive downloads of directories larger than 4 GB are not supported on 32-bit systems\n"));
      return;
    }
  if (dc->filename != NULL)
    {
      h = GNUNET_DISK_file_open (dc->filename,
				 GNUNET_DISK_OPEN_READ,
				 GNUNET_DISK_PERM_NONE);
    }
  else
    {
      GNUNET_assert (dc->temp_filename != NULL);
      h = GNUNET_DISK_file_open (dc->temp_filename,
				 GNUNET_DISK_OPEN_READ,
				 GNUNET_DISK_PERM_NONE);
    }
  if (h == NULL)
    return; /* oops */
  data = GNUNET_DISK_file_map (h, &m, GNUNET_DISK_MAP_TYPE_READ, size);
  if (data == NULL)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
		  _("Directory too large for system address space\n"));
    }
  else
    {
      GNUNET_FS_directory_list_contents (size,
					 data,
					 0,
					 &trigger_recursive_download,
					 dc);         
      GNUNET_DISK_file_unmap (m);
    }
  GNUNET_DISK_file_close (h);
  if (dc->filename == NULL)
    {
      if (0 != UNLINK (dc->temp_filename))
	GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_WARNING,
				  "unlink",
				  dc->temp_filename);
      GNUNET_free (dc->temp_filename);
      dc->temp_filename = NULL;
    }
}


/**
 * Check if all child-downloads have completed and
 * if so, signal completion (and possibly recurse to
 * parent).
 */
static void
check_completed (struct GNUNET_FS_DownloadContext *dc)
{
  struct GNUNET_FS_ProgressInfo pi;
  struct GNUNET_FS_DownloadContext *pos;

  pos = dc->child_head;
  while (pos != NULL)
    {
      if ( (pos->emsg == NULL) &&
	   (pos->completed < pos->length) )
	return; /* not done yet */
      if ( (pos->child_head != NULL) &&
	   (pos->has_finished != GNUNET_YES) )
	return; /* not transitively done yet */
      pos = pos->next;
    }
  dc->has_finished = GNUNET_YES;
  GNUNET_FS_download_sync_ (dc);
  /* signal completion */
  pi.status = GNUNET_FS_STATUS_DOWNLOAD_COMPLETED;
  GNUNET_FS_download_make_status_ (&pi, dc);
  if (dc->parent != NULL)
    check_completed (dc->parent);  
}


/**
 * We found an entry in a directory.  Check if the respective child
 * already exists and if not create the respective child download.
 *
 * @param cls the parent download
 * @param filename name of the file in the directory
 * @param uri URI of the file (CHK or LOC)
 * @param meta meta data of the file
 * @param length number of bytes in data
 * @param data contents of the file (or NULL if they were not inlined)
 */
static void 
trigger_recursive_download (void *cls,
			    const char *filename,
			    const struct GNUNET_FS_Uri *uri,
			    const struct GNUNET_CONTAINER_MetaData *meta,
			    size_t length,
			    const void *data)
{
  struct GNUNET_FS_DownloadContext *dc = cls;  
  struct GNUNET_FS_DownloadContext *cpos;
  struct GNUNET_DISK_FileHandle *fh;
  char *temp_name;
  const char *real_name;
  char *fn;
  char *us;
  char *ext;
  char *dn;
  char *pos;
  char *full_name;

  if (NULL == uri)
    return; /* entry for the directory itself */
  cpos = dc->child_head;
  while (cpos != NULL)
    {
      if ( (GNUNET_FS_uri_test_equal (uri,
				      cpos->uri)) ||
	   ( (filename != NULL) &&
	     (0 == strcmp (cpos->filename,
			   filename)) ) )
	break;	
      cpos = cpos->next;
    }
  if (cpos != NULL)
    return; /* already exists */
  fn = NULL;
  if (NULL == filename)
    {
      fn = GNUNET_FS_meta_data_suggest_filename (meta);
      if (fn == NULL)
	{
	  us = GNUNET_FS_uri_to_string (uri);
	  fn = GNUNET_strdup (&us [strlen (GNUNET_FS_URI_PREFIX 
					   GNUNET_FS_URI_CHK_INFIX)]);
	  GNUNET_free (us);
	}
      else if (fn[0] == '.')
	{
	  ext = fn;
	  us = GNUNET_FS_uri_to_string (uri);
	  GNUNET_asprintf (&fn,
			   "%s%s",
			   &us[strlen (GNUNET_FS_URI_PREFIX 
				       GNUNET_FS_URI_CHK_INFIX)], ext);
	  GNUNET_free (ext);
	  GNUNET_free (us);
	}
      /* change '\' to '/' (this should have happened
       during insertion, but malicious peers may
       not have done this) */
      while (NULL != (pos = strstr (fn, "\\")))
	*pos = '/';
      /* remove '../' everywhere (again, well-behaved
	 peers don't do this, but don't trust that
	 we did not get something nasty) */
      while (NULL != (pos = strstr (fn, "../")))
	{
	  pos[0] = '_';
	  pos[1] = '_';
	  pos[2] = '_';
	}
      filename = fn;
    }
  if (dc->filename == NULL)
    {
      full_name = NULL;
    }
  else
    {
      dn = GNUNET_strdup (dc->filename);
      GNUNET_break ( (strlen (dn) >= strlen (GNUNET_FS_DIRECTORY_EXT)) &&
		     (NULL !=
		      strstr (dn + strlen(dn) - strlen(GNUNET_FS_DIRECTORY_EXT),
			      GNUNET_FS_DIRECTORY_EXT)) );
      if ( (strlen (dn) >= strlen (GNUNET_FS_DIRECTORY_EXT)) &&
	   (NULL !=
	    strstr (dn + strlen(dn) - strlen(GNUNET_FS_DIRECTORY_EXT),
		    GNUNET_FS_DIRECTORY_EXT)) )      
	dn[strlen(dn) - strlen (GNUNET_FS_DIRECTORY_EXT)] = '\0';      
      if ( (GNUNET_YES == GNUNET_FS_meta_data_test_for_directory (meta)) &&
	   ( (strlen (filename) < strlen (GNUNET_FS_DIRECTORY_EXT)) ||
	     (NULL ==
	      strstr (filename + strlen(filename) - strlen(GNUNET_FS_DIRECTORY_EXT),
		      GNUNET_FS_DIRECTORY_EXT)) ) )
	{
	  GNUNET_asprintf (&full_name,
			   "%s%s%s%s",
			   dn,
			   DIR_SEPARATOR_STR,
			   filename,
			   GNUNET_FS_DIRECTORY_EXT);
	}
      else
	{
	  GNUNET_asprintf (&full_name,
			   "%s%s%s",
			   dn,
			   DIR_SEPARATOR_STR,
			   filename);
	}
      GNUNET_free (dn);
    }
  if ( (full_name != NULL) &&
       (GNUNET_OK !=
	GNUNET_DISK_directory_create_for_file (full_name)) )
    {
      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
		  _("Failed to create directory for recursive download of `%s'\n"),
		  full_name);
      GNUNET_free (full_name);
      GNUNET_free_non_null (fn);
      return;
    }

  temp_name = NULL;
  if ( (data != NULL) &&
       (GNUNET_FS_uri_chk_get_file_size (uri) == length) )
    {
      if (full_name == NULL)
	{
	  temp_name = GNUNET_DISK_mktemp ("gnunet-directory-download-tmp");
	  real_name = temp_name;
	}
      else
	{
	  real_name = full_name;
	}
      /* write to disk, then trigger normal download which will instantly progress to completion */
      fh = GNUNET_DISK_file_open (real_name,
				  GNUNET_DISK_OPEN_WRITE | GNUNET_DISK_OPEN_TRUNCATE | GNUNET_DISK_OPEN_CREATE,
				  GNUNET_DISK_PERM_USER_READ | GNUNET_DISK_PERM_USER_WRITE);
      if (fh == NULL)
	{
	  GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_ERROR,
				    "open",
				    real_name);	      
	  GNUNET_free (full_name);
	  GNUNET_free_non_null (fn);
	  return;
	}
      if (length != 
	  GNUNET_DISK_file_write (fh,
				  data,
				  length))
	{
	  GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_ERROR,
				    "write",
				    full_name);	      
	}
      GNUNET_DISK_file_close (fh);
    }
  GNUNET_FS_download_start (dc->h,
			    uri,
			    meta,
			    full_name, temp_name,
			    0,
			    GNUNET_FS_uri_chk_get_file_size (uri),
			    dc->anonymity,
			    dc->options,
			    NULL,
			    dc);
  GNUNET_free_non_null (full_name);
  GNUNET_free_non_null (temp_name);
  GNUNET_free_non_null (fn);
}


/**
 * Free entries in the map.
 *
 * @param cls unused (NULL)
 * @param key unused
 * @param entry entry of type "struct DownloadRequest" which is freed
 * @return GNUNET_OK
 */
static int
free_entry (void *cls,
	    const GNUNET_HashCode *key,
	    void *entry)
{
  GNUNET_free (entry);
  return GNUNET_OK;
}


/**
 * Iterator over entries in the pending requests in the 'active' map for the
 * reply that we just got.
 *
 * @param cls closure (our 'struct ProcessResultClosure')
 * @param key query for the given value / request
 * @param value value in the hash map (a 'struct DownloadRequest')
 * @return GNUNET_YES (we should continue to iterate); unless serious error
 */
static int
process_result_with_request (void *cls,
			     const GNUNET_HashCode * key,
			     void *value)
{
  struct ProcessResultClosure *prc = cls;
  struct DownloadRequest *sm = value;
  struct DownloadRequest *ppos;
  struct DownloadRequest *pprev;
  struct GNUNET_DISK_FileHandle *fh;
  struct GNUNET_FS_DownloadContext *dc = prc->dc;
  struct GNUNET_CRYPTO_AesSessionKey skey;
  struct GNUNET_CRYPTO_AesInitializationVector iv;
  char pt[prc->size];
  struct GNUNET_FS_ProgressInfo pi;
  uint64_t off;
  size_t bs;
  size_t app;
  int i;
  struct ContentHashKey *chk;

  fh = NULL;
  bs = GNUNET_FS_tree_calculate_block_size (GNUNET_ntohll (dc->uri->data.chk.file_length),
					    dc->treedepth,
					    sm->offset,
					    sm->depth);
  if (prc->size != bs)
    {
#if DEBUG_DOWNLOAD
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
		  "Internal error or bogus download URI (expected %u bytes, got %u)\n",
		  bs,
		  prc->size);
#endif
      dc->emsg = GNUNET_strdup ("Internal error or bogus download URI");
      goto signal_error;
    }
  GNUNET_assert (GNUNET_YES ==
		 GNUNET_CONTAINER_multihashmap_remove (dc->active,
						       &prc->query,
						       sm));
  /* if this request is on the pending list, remove it! */
  pprev = NULL;
  ppos = dc->pending;
  while (ppos != NULL)
    {
      if (ppos == sm)
	{
	  if (pprev == NULL)
	    dc->pending = ppos->next;
	  else
	    pprev->next = ppos->next;
	  break;
	}
      pprev = ppos;
      ppos = ppos->next;
    }
  GNUNET_CRYPTO_hash_to_aes_key (&sm->chk.key, &skey, &iv);
  if (-1 == GNUNET_CRYPTO_aes_decrypt (prc->data,
				       prc->size,
				       &skey,
				       &iv,
				       pt))
    {
      GNUNET_break (0);
      dc->emsg = GNUNET_strdup ("internal error decrypting content");
      goto signal_error;
    }
  off = compute_disk_offset (GNUNET_ntohll (dc->uri->data.chk.file_length),
			     sm->offset,
			     sm->depth,
			     dc->treedepth);
  /* save to disk */
  if ( ( GNUNET_YES == prc->do_store) &&
       ( (dc->filename != NULL) ||
	 (is_recursive_download (dc)) ) &&
       ( (sm->depth == dc->treedepth) ||
	 (0 == (dc->options & GNUNET_FS_DOWNLOAD_NO_TEMPORARIES)) ) )
    {
      fh = GNUNET_DISK_file_open (dc->filename != NULL 
				  ? dc->filename 
				  : dc->temp_filename, 
				  GNUNET_DISK_OPEN_READWRITE | 
				  GNUNET_DISK_OPEN_CREATE,
				  GNUNET_DISK_PERM_USER_READ |
				  GNUNET_DISK_PERM_USER_WRITE |
				  GNUNET_DISK_PERM_GROUP_READ |
				  GNUNET_DISK_PERM_OTHER_READ);
    }
  if ( (NULL == fh) &&
       (GNUNET_YES == prc->do_store) &&
       ( (dc->filename != NULL) ||
	 (is_recursive_download (dc)) ) &&
       ( (sm->depth == dc->treedepth) ||
	 (0 == (dc->options & GNUNET_FS_DOWNLOAD_NO_TEMPORARIES)) ) )
    {
      GNUNET_asprintf (&dc->emsg,
		       _("Download failed: could not open file `%s': %s\n"),
		       dc->filename,
		       STRERROR (errno));
      goto signal_error;
    }
  if (fh != NULL)
    {
#if DEBUG_DOWNLOAD
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
		  "Saving decrypted block to disk at offset %llu\n",
		  (unsigned long long) off);
#endif
      if ( (off  != 
	    GNUNET_DISK_file_seek (fh,
				   off,
				   GNUNET_DISK_SEEK_SET) ) )
	{
	  GNUNET_asprintf (&dc->emsg,
			   _("Failed to seek to offset %llu in file `%s': %s\n"),
			   (unsigned long long) off,
			   dc->filename,
			   STRERROR (errno));
	  goto signal_error;
	}
      if (prc->size !=
	  GNUNET_DISK_file_write (fh,
				  pt,
				  prc->size))
	{
	  GNUNET_asprintf (&dc->emsg,
			   _("Failed to write block of %u bytes at offset %llu in file `%s': %s\n"),
			   (unsigned int) prc->size,
			   (unsigned long long) off,
			   dc->filename,
			   STRERROR (errno));
	  goto signal_error;
	}
      GNUNET_break (GNUNET_OK == GNUNET_DISK_file_close (fh));
      fh = NULL;
    }
  if (sm->depth == dc->treedepth) 
    {
      app = prc->size;
      if (sm->offset < dc->offset)
	{
	  /* starting offset begins in the middle of pt,
	     do not count first bytes as progress */
	  GNUNET_assert (app > (dc->offset - sm->offset));
	  app -= (dc->offset - sm->offset);	  
	}
      if (sm->offset + prc->size > dc->offset + dc->length)
	{
	  /* end of block is after relevant range,
	     do not count last bytes as progress */
	  GNUNET_assert (app > (sm->offset + prc->size) - (dc->offset + dc->length));
	  app -= (sm->offset + prc->size) - (dc->offset + dc->length);
	}
      dc->completed += app;

      /* do recursive download if option is set and either meta data
	 says it is a directory or if no meta data is given AND filename 
	 ends in '.gnd' (top-level case) */
      if (is_recursive_download (dc))
	GNUNET_FS_directory_list_contents (prc->size,
					   pt,
					   off,
					   &trigger_recursive_download,
					   dc);         
	    
    }
  pi.status = GNUNET_FS_STATUS_DOWNLOAD_PROGRESS;
  pi.value.download.specifics.progress.data = pt;
  pi.value.download.specifics.progress.offset = sm->offset;
  pi.value.download.specifics.progress.data_len = prc->size;
  pi.value.download.specifics.progress.depth = sm->depth;
  GNUNET_FS_download_make_status_ (&pi, dc);
  GNUNET_assert (dc->completed <= dc->length);
  if (dc->completed == dc->length)
    {
#if DEBUG_DOWNLOAD
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
		  "Download completed, truncating file to desired length %llu\n",
		  (unsigned long long) GNUNET_ntohll (dc->uri->data.chk.file_length));
#endif
      /* truncate file to size (since we store IBlocks at the end) */
      if (dc->filename != NULL)
	{
	  if (0 != truncate (dc->filename,
			     GNUNET_ntohll (dc->uri->data.chk.file_length)))
	    GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_WARNING,
				      "truncate",
				      dc->filename);
	}
      if (dc->job_queue != NULL)
	{
	  GNUNET_FS_dequeue_ (dc->job_queue);
	  dc->job_queue = NULL;
	}
      if (is_recursive_download (dc))
	full_recursive_download (dc);
      if (dc->child_head == NULL)
	{
	  /* signal completion */
	  pi.status = GNUNET_FS_STATUS_DOWNLOAD_COMPLETED;
	  GNUNET_FS_download_make_status_ (&pi, dc);
	  if (dc->parent != NULL)
	    check_completed (dc->parent);
	}
      GNUNET_assert (sm->depth == dc->treedepth);
    }
  if (sm->depth == dc->treedepth) 
    {
      GNUNET_FS_download_sync_ (dc);
      GNUNET_free (sm);      
      return GNUNET_YES;
    }
#if DEBUG_DOWNLOAD
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
	      "Triggering downloads of children (this block was at depth %u and offset %llu)\n",
	      sm->depth,
	      (unsigned long long) sm->offset);
#endif
  GNUNET_assert (0 == (prc->size % sizeof(struct ContentHashKey)));
  chk = (struct ContentHashKey*) pt;
  for (i=(prc->size / sizeof(struct ContentHashKey))-1;i>=0;i--)
    {
      off = compute_dblock_offset (sm->offset,
				   sm->depth,
				   dc->treedepth,
				   i);
      if ( (off + DBLOCK_SIZE >= dc->offset) &&
	   (off < dc->offset + dc->length) ) 
	schedule_block_download (dc,
				 &chk[i],
				 off,
				 sm->depth + 1);
    }
  GNUNET_free (sm);
  GNUNET_FS_download_sync_ (dc);
  return GNUNET_YES;

 signal_error:
  if (fh != NULL)
    GNUNET_DISK_file_close (fh);
  pi.status = GNUNET_FS_STATUS_DOWNLOAD_ERROR;
  pi.value.download.specifics.error.message = dc->emsg;
  GNUNET_FS_download_make_status_ (&pi, dc);
  /* abort all pending requests */
  if (NULL != dc->th)
    {
      GNUNET_CLIENT_notify_transmit_ready_cancel (dc->th);
      dc->th = NULL;
    }
  GNUNET_CLIENT_disconnect (dc->client, GNUNET_NO);
  GNUNET_CONTAINER_multihashmap_iterate (dc->active,
					 &free_entry,
					 NULL);
  dc->pending = NULL;
  dc->client = NULL;
  GNUNET_free (sm);
  GNUNET_FS_download_sync_ (dc);
  return GNUNET_NO;
}


/**
 * Process a download result.
 *
 * @param dc our download context
 * @param type type of the result
 * @param data the (encrypted) response
 * @param size size of data
 */
static void
process_result (struct GNUNET_FS_DownloadContext *dc,
		enum GNUNET_BLOCK_Type type,
		const void *data,
		size_t size)
{
  struct ProcessResultClosure prc;

  prc.dc = dc;
  prc.data = data;
  prc.size = size;
  prc.type = type;
  prc.do_store = GNUNET_YES;
  GNUNET_CRYPTO_hash (data, size, &prc.query);
#if DEBUG_DOWNLOAD
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
	      "Received result for query `%s' from `%s'-service\n",
	      GNUNET_h2s (&prc.query),
	      "FS");
#endif
  GNUNET_CONTAINER_multihashmap_get_multiple (dc->active,
					      &prc.query,
					      &process_result_with_request,
					      &prc);
}


/**
 * Type of a function to call when we receive a message
 * from the service.
 *
 * @param cls closure
 * @param msg message received, NULL on timeout or fatal error
 */
static void 
receive_results (void *cls,
		 const struct GNUNET_MessageHeader * msg)
{
  struct GNUNET_FS_DownloadContext *dc = cls;
  const struct PutMessage *cm;
  uint16_t msize;

  if ( (NULL == msg) ||
       (ntohs (msg->type) != GNUNET_MESSAGE_TYPE_FS_PUT) ||
       (sizeof (struct PutMessage) > ntohs(msg->size)) )
    {
      GNUNET_break (msg == NULL);	
      try_reconnect (dc);
      return;
    }
  msize = ntohs(msg->size);
  cm = (const struct PutMessage*) msg;
  process_result (dc, 
		  ntohl (cm->type),
		  &cm[1],
		  msize - sizeof (struct PutMessage));
  if (dc->client == NULL)
    return; /* fatal error */
  /* continue receiving */
  GNUNET_CLIENT_receive (dc->client,
			 &receive_results,
			 dc,
			 GNUNET_TIME_UNIT_FOREVER_REL);
}



/**
 * We're ready to transmit a search request to the
 * file-sharing service.  Do it.  If there is 
 * more than one request pending, try to send 
 * multiple or request another transmission.
 *
 * @param cls closure
 * @param size number of bytes available in buf
 * @param buf where the callee should write the message
 * @return number of bytes written to buf
 */
static size_t
transmit_download_request (void *cls,
			   size_t size, 
			   void *buf)
{
  struct GNUNET_FS_DownloadContext *dc = cls;
  size_t msize;
  struct SearchMessage *sm;

  dc->th = NULL;
  if (NULL == buf)
    {
#if DEBUG_DOWNLOAD
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
		  "Transmitting download request failed, trying to reconnect\n");
#endif
      try_reconnect (dc);
      return 0;
    }
  GNUNET_assert (size >= sizeof (struct SearchMessage));
  msize = 0;
  sm = buf;
  while ( (dc->pending != NULL) &&
	  (size >= msize + sizeof (struct SearchMessage)) )
    {
#if DEBUG_DOWNLOAD
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
		  "Transmitting download request for `%s' to `%s'-service\n",
		  GNUNET_h2s (&dc->pending->chk.query),
		  "FS");
#endif
      memset (sm, 0, sizeof (struct SearchMessage));
      sm->header.size = htons (sizeof (struct SearchMessage));
      sm->header.type = htons (GNUNET_MESSAGE_TYPE_FS_START_SEARCH);
      if (0 != (dc->options & GNUNET_FS_DOWNLOAD_OPTION_LOOPBACK_ONLY))
	sm->options = htonl (1);
      else
	sm->options = htonl (0);      
      if (dc->pending->depth == dc->treedepth)
	sm->type = htonl (GNUNET_BLOCK_TYPE_DBLOCK);
      else
	sm->type = htonl (GNUNET_BLOCK_TYPE_IBLOCK);
      sm->anonymity_level = htonl (dc->anonymity);
      sm->target = dc->target.hashPubKey;
      sm->query = dc->pending->chk.query;
      dc->pending->is_pending = GNUNET_NO;
      dc->pending = dc->pending->next;
      msize += sizeof (struct SearchMessage);
      sm++;
    }
  if (dc->pending != NULL)
    dc->th = GNUNET_CLIENT_notify_transmit_ready (dc->client,
						  sizeof (struct SearchMessage),
						  GNUNET_CONSTANTS_SERVICE_TIMEOUT,
						  GNUNET_NO,
						  &transmit_download_request,
						  dc); 
  return msize;
}


/**
 * Reconnect to the FS service and transmit our queries NOW.
 *
 * @param cls our download context
 * @param tc unused
 */
static void
do_reconnect (void *cls,
	      const struct GNUNET_SCHEDULER_TaskContext *tc)
{
  struct GNUNET_FS_DownloadContext *dc = cls;
  struct GNUNET_CLIENT_Connection *client;
  
  dc->task = GNUNET_SCHEDULER_NO_TASK;
  client = GNUNET_CLIENT_connect (dc->h->sched,
				  "fs",
				  dc->h->cfg);
  if (NULL == client)
    {
      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
		  "Connecting to `%s'-service failed, will try again.\n",
		  "FS");
      try_reconnect (dc);
      return;
    }
  dc->client = client;
  dc->th = GNUNET_CLIENT_notify_transmit_ready (client,
						sizeof (struct SearchMessage),
						GNUNET_CONSTANTS_SERVICE_TIMEOUT,
						GNUNET_NO,
						&transmit_download_request,
						dc);  
  GNUNET_CLIENT_receive (client,
			 &receive_results,
			 dc,
			 GNUNET_TIME_UNIT_FOREVER_REL);
}


/**
 * Add entries that are not yet pending back to the pending list.
 *
 * @param cls our download context
 * @param key unused
 * @param entry entry of type "struct DownloadRequest"
 * @return GNUNET_OK
 */
static int
retry_entry (void *cls,
	     const GNUNET_HashCode *key,
	     void *entry)
{
  struct GNUNET_FS_DownloadContext *dc = cls;
  struct DownloadRequest *dr = entry;

  if (! dr->is_pending)
    {
      dr->next = dc->pending;
      dr->is_pending = GNUNET_YES;
      dc->pending = entry;
    }
  return GNUNET_OK;
}


/**
 * We've lost our connection with the FS service.
 * Re-establish it and re-transmit all of our
 * pending requests.
 *
 * @param dc download context that is having trouble
 */
static void
try_reconnect (struct GNUNET_FS_DownloadContext *dc)
{
  
  if (NULL != dc->client)
    {
#if DEBUG_DOWNLOAD
      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
		  "Moving all requests back to pending list\n");
#endif
      if (NULL != dc->th)
	{
	  GNUNET_CLIENT_notify_transmit_ready_cancel (dc->th);
	  dc->th = NULL;
	}
      GNUNET_CONTAINER_multihashmap_iterate (dc->active,
					     &retry_entry,
					     dc);
      GNUNET_CLIENT_disconnect (dc->client, GNUNET_NO);
      dc->client = NULL;
    }
#if DEBUG_DOWNLOAD
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
	      "Will try to reconnect in 1s\n");
#endif
  dc->task
    = GNUNET_SCHEDULER_add_delayed (dc->h->sched,
				    GNUNET_TIME_UNIT_SECONDS,
				    &do_reconnect,
				    dc);
}



/**
 * We're allowed to ask the FS service for our blocks.  Start the download.
 *
 * @param cls the 'struct GNUNET_FS_DownloadContext'
 * @param client handle to use for communcation with FS (we must destroy it!)
 */
static void
activate_fs_download (void *cls,
		      struct GNUNET_CLIENT_Connection *client)
{
  struct GNUNET_FS_DownloadContext *dc = cls;
  struct GNUNET_FS_ProgressInfo pi;

#if DEBUG_DOWNLOAD
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
	      "Download activated\n");
#endif
  GNUNET_assert (NULL != client);
  GNUNET_assert (dc->client == NULL);
  GNUNET_assert (dc->th == NULL);
  dc->client = client;
  GNUNET_CLIENT_receive (client,
			 &receive_results,
			 dc,
			 GNUNET_TIME_UNIT_FOREVER_REL);
  pi.status = GNUNET_FS_STATUS_DOWNLOAD_ACTIVE;
  GNUNET_FS_download_make_status_ (&pi, dc);
  GNUNET_CONTAINER_multihashmap_iterate (dc->active,
					 &retry_entry,
					 dc);
#if DEBUG_DOWNLOAD
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
	      "Asking for transmission to FS service\n");
#endif
  dc->th = GNUNET_CLIENT_notify_transmit_ready (dc->client,
						sizeof (struct SearchMessage),
						GNUNET_CONSTANTS_SERVICE_TIMEOUT,
						GNUNET_NO,
						&transmit_download_request,
						dc);    
  GNUNET_assert (dc->th != NULL);
}


/**
 * We must stop to ask the FS service for our blocks.  Pause the download.
 *
 * @param cls the 'struct GNUNET_FS_DownloadContext'
 */
static void
deactivate_fs_download (void *cls)
{
  struct GNUNET_FS_DownloadContext *dc = cls;
  struct GNUNET_FS_ProgressInfo pi;

#if DEBUG_DOWNLOAD
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
	      "Download deactivated\n");
#endif  
  if (NULL != dc->th)
    {
      GNUNET_CLIENT_notify_transmit_ready_cancel (dc->th);
      dc->th = NULL;
    }
  if (NULL != dc->client)
    {
      GNUNET_CLIENT_disconnect (dc->client, GNUNET_NO);
      dc->client = NULL;
    }
  pi.status = GNUNET_FS_STATUS_DOWNLOAD_INACTIVE;
  GNUNET_FS_download_make_status_ (&pi, dc);
}


/**
 * Create SUSPEND event for the given download operation
 * and then clean up our state (without stop signal).
 *
 * @param cls the 'struct GNUNET_FS_DownloadContext' to signal for
 */
void
GNUNET_FS_download_signal_suspend_ (void *cls)
{
  struct GNUNET_FS_DownloadContext *dc = cls;
  struct GNUNET_FS_ProgressInfo pi;
  
  if (dc->top != NULL)
    GNUNET_FS_end_top (dc->h, dc->top);
  while (NULL != dc->child_head)
    GNUNET_FS_download_signal_suspend_ (dc->child_head);  
  if (dc->search != NULL)
    {
      dc->search->download = NULL;
      dc->search = NULL;
    }
  if (dc->job_queue != NULL)
    {
      GNUNET_FS_dequeue_ (dc->job_queue);
      dc->job_queue = NULL;
    }
  if (dc->parent != NULL)
    GNUNET_CONTAINER_DLL_remove (dc->parent->child_head,
				 dc->parent->child_tail,
				 dc);  
  pi.status = GNUNET_FS_STATUS_DOWNLOAD_SUSPEND;
  GNUNET_FS_download_make_status_ (&pi, dc);
  if (GNUNET_SCHEDULER_NO_TASK != dc->task)
    GNUNET_SCHEDULER_cancel (dc->h->sched,
			     dc->task);
  GNUNET_CONTAINER_multihashmap_iterate (dc->active,
					 &free_entry,
					 NULL);
  GNUNET_CONTAINER_multihashmap_destroy (dc->active);
  GNUNET_free_non_null (dc->filename);
  GNUNET_CONTAINER_meta_data_destroy (dc->meta);
  GNUNET_FS_uri_destroy (dc->uri);
  GNUNET_free_non_null (dc->temp_filename);
  GNUNET_free_non_null (dc->serialization);
  GNUNET_free (dc);
}


/**
 * Download parts of a file.  Note that this will store
 * the blocks at the respective offset in the given file.  Also, the
 * download is still using the blocking of the underlying FS
 * encoding.  As a result, the download may *write* outside of the
 * given boundaries (if offset and length do not match the 32k FS
 * block boundaries). <p>
 *
 * This function should be used to focus a download towards a
 * particular portion of the file (optimization), not to strictly
 * limit the download to exactly those bytes.
 *
 * @param h handle to the file sharing subsystem
 * @param uri the URI of the file (determines what to download); CHK or LOC URI
 * @param meta known metadata for the file (can be NULL)
 * @param filename where to store the file, maybe NULL (then no file is
 *        created on disk and data must be grabbed from the callbacks)
 * @param tempname where to store temporary file data, not used if filename is non-NULL;
 *        can be NULL (in which case we will pick a name if needed); the temporary file
 *        may already exist, in which case we will try to use the data that is there and
 *        if it is not what is desired, will overwrite it
 * @param offset at what offset should we start the download (typically 0)
 * @param length how many bytes should be downloaded starting at offset
 * @param anonymity anonymity level to use for the download
 * @param options various options
 * @param cctx initial value for the client context for this download
 * @param parent parent download to associate this download with (use NULL
 *        for top-level downloads; useful for manually-triggered recursive downloads)
 * @return context that can be used to control this download
 */
struct GNUNET_FS_DownloadContext *
GNUNET_FS_download_start (struct GNUNET_FS_Handle *h,
			  const struct GNUNET_FS_Uri *uri,
			  const struct GNUNET_CONTAINER_MetaData *meta,
			  const char *filename,
			  const char *tempname,
			  uint64_t offset,
			  uint64_t length,
			  uint32_t anonymity,
			  enum GNUNET_FS_DownloadOptions options,
			  void *cctx,
			  struct GNUNET_FS_DownloadContext *parent)
{
  struct GNUNET_FS_ProgressInfo pi;
  struct GNUNET_FS_DownloadContext *dc;

  GNUNET_assert (GNUNET_FS_uri_test_chk (uri));
  if ( (offset + length < offset) ||
       (offset + length > uri->data.chk.file_length) )
    {      
      GNUNET_break (0);
      return NULL;
    }
#if DEBUG_DOWNLOAD
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
	      "Starting download `%s' of %llu bytes\n",
	      filename,
	      (unsigned long long) length);
#endif
  dc = GNUNET_malloc (sizeof(struct GNUNET_FS_DownloadContext));
  dc->h = h;
  dc->parent = parent;
  if (parent != NULL)
    {
      GNUNET_CONTAINER_DLL_insert (parent->child_head,
				   parent->child_tail,
				   dc);
    }
  dc->uri = GNUNET_FS_uri_dup (uri);
  dc->meta = GNUNET_CONTAINER_meta_data_duplicate (meta);
  dc->client_info = cctx;
  dc->start_time = GNUNET_TIME_absolute_get ();
  if (NULL != filename)
    {
      dc->filename = GNUNET_strdup (filename);
      if (GNUNET_YES == GNUNET_DISK_file_test (filename))
	GNUNET_DISK_file_size (filename,
			       &dc->old_file_size,
			       GNUNET_YES);
    }
  if (GNUNET_FS_uri_test_loc (dc->uri))
    GNUNET_assert (GNUNET_OK ==
		   GNUNET_FS_uri_loc_get_peer_identity (dc->uri,
							&dc->target));
  dc->offset = offset;
  dc->length = length;
  dc->anonymity = anonymity;
  dc->options = options;
  dc->active = GNUNET_CONTAINER_multihashmap_create (1 + 2 * (length / DBLOCK_SIZE));
  dc->treedepth = GNUNET_FS_compute_depth (GNUNET_ntohll(dc->uri->data.chk.file_length));
  if ( (filename == NULL) &&
       (is_recursive_download (dc) ) )
    {
      if (tempname != NULL)
	dc->temp_filename = GNUNET_strdup (tempname);
      else
	dc->temp_filename = GNUNET_DISK_mktemp ("gnunet-directory-download-tmp");    
    }

#if DEBUG_DOWNLOAD
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
	      "Download tree has depth %u\n",
	      dc->treedepth);
#endif
  if (parent == NULL)
    {
      dc->top = GNUNET_FS_make_top (dc->h,
				    &GNUNET_FS_download_signal_suspend_,
				    dc);
    }
  pi.status = GNUNET_FS_STATUS_DOWNLOAD_START;
  pi.value.download.specifics.start.meta = meta;
  GNUNET_FS_download_make_status_ (&pi, dc);
  schedule_block_download (dc, 
			   &dc->uri->data.chk.chk,
			   0, 
			   1 /* 0 == CHK, 1 == top */); 
  GNUNET_FS_download_sync_ (dc);
  GNUNET_FS_download_start_downloading_ (dc);
  return dc;
}


/**
 * Download parts of a file based on a search result.  The download
 * will be associated with the search result (and the association
 * will be preserved when serializing/deserializing the state).
 * If the search is stopped, the download will not be aborted but
 * be 'promoted' to a stand-alone download.
 *
 * As with the other download function, this will store
 * the blocks at the respective offset in the given file.  Also, the
 * download is still using the blocking of the underlying FS
 * encoding.  As a result, the download may *write* outside of the
 * given boundaries (if offset and length do not match the 32k FS
 * block boundaries). <p>
 *
 * The given range can be used to focus a download towards a
 * particular portion of the file (optimization), not to strictly
 * limit the download to exactly those bytes.
 *
 * @param h handle to the file sharing subsystem
 * @param sr the search result to use for the download (determines uri and
 *        meta data and associations)
 * @param filename where to store the file, maybe NULL (then no file is
 *        created on disk and data must be grabbed from the callbacks)
 * @param tempname where to store temporary file data, not used if filename is non-NULL;
 *        can be NULL (in which case we will pick a name if needed); the temporary file
 *        may already exist, in which case we will try to use the data that is there and
 *        if it is not what is desired, will overwrite it
 * @param offset at what offset should we start the download (typically 0)
 * @param length how many bytes should be downloaded starting at offset
 * @param anonymity anonymity level to use for the download
 * @param options various download options
 * @param cctx initial value for the client context for this download
 * @return context that can be used to control this download
 */
struct GNUNET_FS_DownloadContext *
GNUNET_FS_download_start_from_search (struct GNUNET_FS_Handle *h,
				      struct GNUNET_FS_SearchResult *sr,
				      const char *filename,
				      const char *tempname,
				      uint64_t offset,
				      uint64_t length,
				      uint32_t anonymity,
				      enum GNUNET_FS_DownloadOptions options,
				      void *cctx)
{
  struct GNUNET_FS_ProgressInfo pi;
  struct GNUNET_FS_DownloadContext *dc;

  if ( (sr == NULL) ||
       (sr->download != NULL) )
    {
      GNUNET_break (0);
      return NULL;
    }
  GNUNET_assert (GNUNET_FS_uri_test_chk (sr->uri));
  if ( (offset + length < offset) ||
       (offset + length > sr->uri->data.chk.file_length) )
    {      
      GNUNET_break (0);
      return NULL;
    }
#if DEBUG_DOWNLOAD
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
	      "Starting download `%s' of %llu bytes\n",
	      filename,
	      (unsigned long long) length);
#endif
  dc = GNUNET_malloc (sizeof(struct GNUNET_FS_DownloadContext));
  dc->h = h;
  dc->search = sr;
  sr->download = dc;
  if (sr->probe_ctx != NULL)
    {
      GNUNET_FS_download_stop (sr->probe_ctx, GNUNET_YES);
      sr->probe_ctx = NULL;      
    }
  dc->uri = GNUNET_FS_uri_dup (sr->uri);
  dc->meta = GNUNET_CONTAINER_meta_data_duplicate (sr->meta);
  dc->client_info = cctx;
  dc->start_time = GNUNET_TIME_absolute_get ();
  if (NULL != filename)
    {
      dc->filename = GNUNET_strdup (filename);
      if (GNUNET_YES == GNUNET_DISK_file_test (filename))
	GNUNET_DISK_file_size (filename,
			       &dc->old_file_size,
			       GNUNET_YES);
    }
  if (GNUNET_FS_uri_test_loc (dc->uri))
    GNUNET_assert (GNUNET_OK ==
		   GNUNET_FS_uri_loc_get_peer_identity (dc->uri,
							&dc->target));
  dc->offset = offset;
  dc->length = length;
  dc->anonymity = anonymity;
  dc->options = options;
  dc->active = GNUNET_CONTAINER_multihashmap_create (1 + 2 * (length / DBLOCK_SIZE));
  dc->treedepth = GNUNET_FS_compute_depth (GNUNET_ntohll(dc->uri->data.chk.file_length));
  if ( (filename == NULL) &&
       (is_recursive_download (dc) ) )
    {
      if (tempname != NULL)
	dc->temp_filename = GNUNET_strdup (tempname);
      else
	dc->temp_filename = GNUNET_DISK_mktemp ("gnunet-directory-download-tmp");    
    }

#if DEBUG_DOWNLOAD
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
	      "Download tree has depth %u\n",
	      dc->treedepth);
#endif
  pi.status = GNUNET_FS_STATUS_DOWNLOAD_START;
  pi.value.download.specifics.start.meta = dc->meta;
  GNUNET_FS_download_make_status_ (&pi, dc);
  schedule_block_download (dc, 
			   &dc->uri->data.chk.chk,
			   0, 
			   1 /* 0 == CHK, 1 == top */); 
  GNUNET_FS_download_sync_ (dc);
  GNUNET_FS_download_start_downloading_ (dc);
  return dc;  
}


/**
 * Start the downloading process (by entering the queue).
 *
 * @param dc our download context
 */
void
GNUNET_FS_download_start_downloading_ (struct GNUNET_FS_DownloadContext *dc)
{
  GNUNET_assert (dc->job_queue == NULL);
  dc->job_queue = GNUNET_FS_queue_ (dc->h, 
				    &activate_fs_download,
				    &deactivate_fs_download,
				    dc,
				    (dc->length + DBLOCK_SIZE-1) / DBLOCK_SIZE);
}


/**
 * Stop a download (aborts if download is incomplete).
 *
 * @param dc handle for the download
 * @param do_delete delete files of incomplete downloads
 */
void
GNUNET_FS_download_stop (struct GNUNET_FS_DownloadContext *dc,
			 int do_delete)
{
  struct GNUNET_FS_ProgressInfo pi;
  int have_children;

  if (dc->top != NULL)
    GNUNET_FS_end_top (dc->h, dc->top);
  if (dc->search != NULL)
    {
      dc->search->download = NULL;
      dc->search = NULL;
    }
  if (dc->job_queue != NULL)
    {
      GNUNET_FS_dequeue_ (dc->job_queue);
      dc->job_queue = NULL;
    }
  have_children = (NULL != dc->child_head) ? GNUNET_YES : GNUNET_NO;
  while (NULL != dc->child_head)
    GNUNET_FS_download_stop (dc->child_head, 
			     do_delete);
  if (dc->parent != NULL)
    GNUNET_CONTAINER_DLL_remove (dc->parent->child_head,
				 dc->parent->child_tail,
				 dc);  
  if (dc->serialization != NULL)
    GNUNET_FS_remove_sync_file_ (dc->h,
				 ( (dc->parent != NULL)  || (dc->search != NULL) )
				 ? GNUNET_FS_SYNC_PATH_CHILD_DOWNLOAD 
				 : GNUNET_FS_SYNC_PATH_MASTER_DOWNLOAD , 
				 dc->serialization);
  if ( (GNUNET_YES == have_children) &&
       (dc->parent == NULL) )
    GNUNET_FS_remove_sync_dir_ (dc->h, 
				(dc->search != NULL) 
				? GNUNET_FS_SYNC_PATH_CHILD_DOWNLOAD 
				: GNUNET_FS_SYNC_PATH_MASTER_DOWNLOAD,
				dc->serialization);  
  pi.status = GNUNET_FS_STATUS_DOWNLOAD_STOPPED;
  GNUNET_FS_download_make_status_ (&pi, dc);
  if (GNUNET_SCHEDULER_NO_TASK != dc->task)
    GNUNET_SCHEDULER_cancel (dc->h->sched,
			     dc->task);
  GNUNET_CONTAINER_multihashmap_iterate (dc->active,
					 &free_entry,
					 NULL);
  GNUNET_CONTAINER_multihashmap_destroy (dc->active);
  if (dc->filename != NULL)
    {
      if ( (dc->completed != dc->length) &&
	   (GNUNET_YES == do_delete) )
	{
	  if (0 != UNLINK (dc->filename))
	    GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_WARNING,
				      "unlink",
				      dc->filename);
	}
      GNUNET_free (dc->filename);
    }
  GNUNET_CONTAINER_meta_data_destroy (dc->meta);
  GNUNET_FS_uri_destroy (dc->uri);
  if (NULL != dc->temp_filename)
    {
      if (0 != UNLINK (dc->temp_filename))
	GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_ERROR,
				  "unlink",
				  dc->temp_filename);
      GNUNET_free (dc->temp_filename);
    }
  GNUNET_free_non_null (dc->serialization);
  GNUNET_free (dc);
}

/* end of fs_download.c */