我该如何阅读 BitTorrent 作品？

Question

我目前正在为 Ruby 开发一个 torrent 元信息管理库。

我在读取文件中的片段时遇到问题。我只是不明白我该怎么做。我知道我应该对文件的片段长度字节进行一次SHA1摘要（或多次读取片段长度字节，或者什么？）

我指望你的帮助。 伪/Python/Ruby/PHP 代码优先。

提前致谢。

Answer 1

C#

// Open the file
using (var file = File.Open(...))
{
    // Move to the relevant place in the file where the piece begins
    file.Seek(piece * pieceLength, SeekOrigin.Begin);

    // Attempt to read up to pieceLength bytes from the file into a buffer
    byte[] buffer = new byte[pieceLength];
    int totalRead = 0;
    while (totalRead < pieceLength)
    {
        var read = stream.Read(buffer, totalRead, pieceLength-totalRead);
        if (read == 0)
        {
            // the piece is smaller than the pieceLength,
            // because it’s the last in the file
            Array.Resize(ref buffer, totalRead);
            break;
        }
        totalRead += read;
    }

    // If you want the raw data for the piece:
    return buffer;

    // If you want the SHA1 hashsum:
    return SHA1.Create().ComputeHash(buffer);
}

Answer 2

请在此处查看此发行版：

http://prdownload.berlios.de /torrentparse/TorrentParse.GTK.0.21.zip

用 PHP 编写，它包含一个编码器和解码器以及我相信的输入和输出！