我对种子了解不多，至少不足以了解某些网站如何同时提供普通下载链接和种子链接来下载用户上传的文件。
正在生成一个种子链接，这是一种常见且易于实现的东西。我需要安装服务器吗？
我从 Java 源代码制作了一个丑陋的 C# 实现，为了确保我的一些编码变量是正确的，我使用了来自 Lars Warholm 的 NBEncode 。
// There are 'args' because I'm using it from command-line. (arg0 is an option not used here)
// Source file
args[1] = Directory.GetCurrentDirectory() + args[1];
// Name to give to the torrent file
args[2] = Directory.GetCurrentDirectory() + args[2];
var inFileStream = new FileStream(args[1], FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
var filename = args[2];
//BEncoding with NBEencode
var transform = new BObjectTransform();
MemoryStream s = new MemoryStream();
OSS.NBEncode.Entities.BDictionary bod = new OSS.NBEncode.Entities.BDictionary();
OSS.NBEncode.Entities.BDictionary meta = new OSS.NBEncode.Entities.BDictionary();
// Preparing the first part of the file by creating BEncoded objects
string announceURL = "https://www.mysite.com/announce";
int pieceLength = 512 * 1024;
bod.Value.Add(new BByteString("name"), new OSS.NBEncode.Entities.BByteString(filename));
bod.Value.Add(new BByteString("length"), new OSS.NBEncode.Entities.BInteger(inFileStream.Length));
bod.Value.Add(new BByteString("piece length"), new OSS.NBEncode.Entities.BInteger(pieceLength));
bod.Value.Add(new BByteString("pieces"), new BByteString(""));
meta.Value.Add(new BByteString("announce"), new BByteString(announceURL));
meta.Value.Add(new BByteString("info"), bod);
byte[] pieces = hashPieces(args[1], pieceLength);
transform.EncodeObject(meta, s);
s.Close();
// Notice that we finish with a dictionary entry of "pieces" with an empty string.
byte[] trs = s.ToArray();
s.Close();
inFileStream.Close();
// I don't know how to write array of bytes using NBEncode library, so let's continue manually
// All data has been written a MemoryStreamp, except the byte array with the hash info about each parts of the file
Stream st = new FileStream(filename + ".torrent", FileMode.Create);
BinaryWriter bw = new BinaryWriter(st);
// Let's write these Bencoded variables to the torrent file:
// The -4 is there to skip the current end of the file created by NBEncode
for (int i = 0; i < trs.Length - 4; i++)
{
bw.BaseStream.WriteByte(trs[i]);
}
// We'll add the length of the pieces SHA1 hashes:
var bt = stringToBytes(pieces.Length.ToString() + ":");
// Then we'll close the Bencoded dictionary with 'ee'
var bu = stringToBytes("ee");
// Let's append this to the end of the file.
foreach (byte b in bt)
{
bw.BaseStream.WriteByte(b);
}
foreach (byte b in pieces)
{
bw.BaseStream.WriteByte(b);
}
foreach (byte b in bu)
{
bw.BaseStream.WriteByte(b);
}
bw.Close();
st.Close();
// That's it.
}
使用的功能：
private static byte[] stringToBytes(String str)
{
System.Text.UTF8Encoding encoding = new System.Text.UTF8Encoding();
Byte[] bytes = encoding.GetBytes(str);
return bytes;
}
private static byte[] hashPieces(string file, int pieceLength)
{
SHA1 sha1 = new SHA1CryptoServiceProvider();
StreamReader inn = new StreamReader(file);
MemoryStream pieces = new MemoryStream();
byte[] bytes = new byte[pieceLength];
byte[] digest = new byte[20];
int pieceByteCount = 0, readCount = inn.BaseStream.Read(bytes, 0, pieceLength);
while (readCount != 0)
{
pieceByteCount += readCount;
digest = sha1.ComputeHash(bytes, 0, readCount);
if (pieceByteCount == pieceLength)
{
pieceByteCount = 0;
foreach (byte b in digest)
{
pieces.WriteByte(b);
}
}
readCount = inn.BaseStream.Read(bytes, 0, pieceLength - pieceByteCount);
}
inn.Close();
if (pieceByteCount > 0)
foreach (byte b in digest)
{
pieces.WriteByte(b);
}
return pieces.ToArray();
}