Torrent 管理：UDP 协议错误

Question

我正在尝试使用 jlibitorrent 库在 java 中开发一个 torrent 管理器，但是当执行该程序时我收到以下错误：

Bencoding Exception: unknown protocol: udp at com.torrent.util.TorrentInfo.(TorrentInfo.java:160) at st.ST.main(ST.java:70)

程序的参数是从网上下载的torrent，传输也可以。

给我报错信息的函数代码是：

@SuppressWarnings("unchecked")
public TorrentInfo(byte[] torrent_file_bytes) throws BencodingException
{   
    // Make sure the input is valid
    if(torrent_file_bytes == null || torrent_file_bytes.length == 0)
        throw new IllegalArgumentException("Torrent file bytes must be non-null and have at least 1 byte.");

    // Assign the byte array
    this.torrent_file_bytes = torrent_file_bytes;

    // Assign the metainfo map
    this.torrent_file_map = (Map<ByteBuffer,Object>)Bencoder2.decode(torrent_file_bytes);

    // Try to extract the announce URL
    ByteBuffer url_buff = (ByteBuffer)this.torrent_file_map.get(TorrentInfo.KEY_ANNOUNCE);
    if(url_buff == null)
        throw new BencodingException("Could not retrieve anounce URL from torrent metainfo.  Corrupt file?");

    try {
        String url_string = new String(url_buff.array(), "ASCII");
        URL announce_url = new URL(url_string);
        this.announce_url = announce_url;
    }
    catch(UnsupportedEncodingException uee)
    {
        throw new BencodingException(uee.getLocalizedMessage());
    }
    catch(MalformedURLException murle)
    {
        throw new BencodingException(murle.getLocalizedMessage());
    }

    // Try to extract the info dictionary
    ByteBuffer info_bytes = Bencoder2.getInfoBytes(torrent_file_bytes);
    Map<ByteBuffer,Object> info_map = (Map<ByteBuffer,Object>)this.torrent_file_map.get(TorrentInfo.KEY_INFO);

    if(info_map == null)
        throw new BencodingException("Could not extract info dictionary from torrent metainfo dictionary.  Corrupt file?");
    this.info_map = info_map;

    // Try to generate the info hash value
    try {
        MessageDigest digest = MessageDigest.getInstance("SHA-1");
        digest.update(info_bytes.array());
        byte[] info_hash = digest.digest();
        this.info_hash = ByteBuffer.wrap(info_hash);
    }
    catch(NoSuchAlgorithmException nsae)
    {
        throw new BencodingException(nsae.getLocalizedMessage());
    }

    // Extract the piece length from the info dictionary
    Integer piece_length = (Integer)this.info_map.get(TorrentInfo.KEY_PIECE_LENGTH);
    if(piece_length == null)
        throw new BencodingException("Could not extract piece length from info dictionary.  Corrupt file?");
    this.piece_length = piece_length.intValue();

    // Extract the file name from the info dictionary
    ByteBuffer name_bytes = (ByteBuffer)this.info_map.get(TorrentInfo.KEY_NAME);
    if(name_bytes == null)
        throw new BencodingException("Could not retrieve file name from info dictionary.  Corrupt file?");
    try {
        this.file_name = new String(name_bytes.array(),"ASCII");
    }
    catch(UnsupportedEncodingException uee)
    {
        throw new BencodingException(uee.getLocalizedMessage());
    }

    // Extract the file length from the info dictionary
    Integer file_length = (Integer)this.info_map.get(TorrentInfo.KEY_LENGTH);
    if(file_length == null)
        throw new BencodingException("Could not extract file length from info dictionary.  Corrupt file?");
    this.file_length = file_length.intValue();

    // Extract the piece hashes from the info dictionary
    ByteBuffer all_hashes = (ByteBuffer)this.info_map.get(TorrentInfo.KEY_PIECES);
    if(all_hashes == null)
        throw new BencodingException("Could not extract piece hashes from info dictionary.  Corrupt file?");
    byte[] all_hashes_array = all_hashes.array();

    // Verify that the length of the array is a multiple of 20 bytes (160 bits)
    if(all_hashes_array.length % 20 != 0)
        throw new BencodingException("Piece hashes length is not a multiple of 20.  Corrupt file?");
    int num_pieces = all_hashes_array.length / 20;

    // Copy the values of the piece hashes into the local field
    this.piece_hashes = new ByteBuffer[num_pieces];
    for(int i = 0; i < num_pieces; i++)
    {
        byte[] temp_buff = new byte[20];
        System.arraycopy(all_hashes_array,i*20,temp_buff,0,20);
        this.piece_hashes[i] = ByteBuffer.wrap(temp_buff);
    }
}

}

我看了两天代码，不知道哪里出错了，非常感谢大家的帮助。谢谢

Answer 1

Torrents 可以包含 udp://... 宣布用于 UDP trackers 的 URLs。虽然方案名称有点过于通用，但事实就是如此。

默认情况下，

Java 的 URL class 无法处理这些。有关可能的解决方案，请参阅 this SO question。

有人可能会争辩说这是库中的一个错误，因为它不仅仅是 return 一个字符串，因此 Torrent 解码不会仅仅因为格式错误或未知的 URI 而中止。实现在他们接受的内容上应该是自由的（在合理范围内），所以在这种情况下，他们应该简单地过滤掉他们无法处理的 URI 方案。

Torrent 管理：UDP 协议错误

Torrent Management: error with protocol UDP

java

bittorrent

torrent