forked from anacrolix/torrent
-
Notifications
You must be signed in to change notification settings - Fork 0
/
misc.go
87 lines (76 loc) · 2.13 KB
/
misc.go
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
package torrent
import (
"errors"
"github.com/anacrolix/torrent/metainfo"
pp "github.com/anacrolix/torrent/peer_protocol"
)
type chunkSpec struct {
Begin, Length pp.Integer
}
type request struct {
Index pp.Integer
chunkSpec
}
func newRequest(index, begin, length pp.Integer) request {
return request{index, chunkSpec{begin, length}}
}
// The size in bytes of a metadata extension piece.
func metadataPieceSize(totalSize int, piece int) int {
ret := totalSize - piece*(1<<14)
if ret > 1<<14 {
ret = 1 << 14
}
return ret
}
// Return the request that would include the given offset into the torrent data.
func torrentOffsetRequest(torrentLength, pieceSize, chunkSize, offset int64) (
r request, ok bool) {
if offset < 0 || offset >= torrentLength {
return
}
r.Index = pp.Integer(offset / pieceSize)
r.Begin = pp.Integer(offset % pieceSize / chunkSize * chunkSize)
r.Length = pp.Integer(chunkSize)
pieceLeft := pp.Integer(pieceSize - int64(r.Begin))
if r.Length > pieceLeft {
r.Length = pieceLeft
}
torrentLeft := torrentLength - int64(r.Index)*pieceSize - int64(r.Begin)
if int64(r.Length) > torrentLeft {
r.Length = pp.Integer(torrentLeft)
}
ok = true
return
}
func torrentRequestOffset(torrentLength, pieceSize int64, r request) (off int64) {
off = int64(r.Index)*pieceSize + int64(r.Begin)
if off < 0 || off >= torrentLength {
panic("invalid request")
}
return
}
func validateInfo(info *metainfo.Info) error {
if len(info.Pieces)%20 != 0 {
return errors.New("pieces has invalid length")
}
if info.PieceLength == 0 {
if info.TotalLength() != 0 {
return errors.New("zero piece length")
}
} else {
if int((info.TotalLength()+info.PieceLength-1)/info.PieceLength) != info.NumPieces() {
return errors.New("piece count and file lengths are at odds")
}
}
return nil
}
func chunkIndexSpec(index int, pieceLength, chunkSize pp.Integer) chunkSpec {
ret := chunkSpec{pp.Integer(index) * chunkSize, chunkSize}
if ret.Begin+ret.Length > pieceLength {
ret.Length = pieceLength - ret.Begin
}
return ret
}
func connLessTrusted(l, r *connection) bool {
return l.netGoodPiecesDirtied() < r.netGoodPiecesDirtied()
}