/// <summary>
/// Computes the "info_hash" of the provided torrent (BDictionary).
/// </summary>
/// <param name="torrent">The BDicionary containing the torrent file.</param>
/// <returns>An InfoHash object with the SHA1 hash.</returns>
public static InfoHash ComputeInfoHash(BDictionary torrent)
{
IBValue info = null;
//looks for the "info" dictionary
foreach (KeyValuePair <string, IBValue> item in torrent.Items)
{
if (item.Key == "info" && item.Value is BDictionary)
{
info = item.Value;
break;
}
}
//if found, then computes the SHA1 hash and returns it
if (info != null)
{
//the info_hash is the sha1 hash of the bencoded "info" dictionary, so gets it
string bencoded = info.ToBEncodedString();
List <byte> bytes = new List <byte>(bencoded.Length);
//adds its bytes to a list to be used in the ComputeHash function
foreach (char c in info.ToBEncodedString())
{
bytes.Add((byte)c);
}
SHA1 sha1 = SHA1.Create();
return(InfoHash.FromByteArray(sha1.ComputeHash(bytes.ToArray())));
}
//if the "info" dictionary is not found, then returns an empty InfoHash to avoid exceptions...
return(InfoHash.FromByteArray(new byte[] { }));
}
/// <summary>
/// 解读一条用户连接消息。
/// </summary>
/// <param name="message">待解读的消息。</param>
/// <param name="infoHash">解读出的 InfoHash。</param>
/// <param name="bitTorrentClientPort">解读出的用户监听端口。</param>
/// <exception cref="System.ArgumentException">解读的不是用户连接消息时发生。</exception>
public static void GetPeerMessageContent(KMessage message, out InfoHash infoHash, out ushort bitTorrentClientPort)
{
//if (message.Content.Data.Length != 22)
//{
// throw new ArgumentException("要解读的不是一条用户连接消息。");
//}
//infoHash = InfoHash.FromByteArray(message.Content.Data.Take(20).ToArray());
//bitTorrentClientPort = BitConverter.ToUInt16(message.Content.Data, 20);
BEncodedDictionary dictionary;
try
{
dictionary = BEncodedValue.Decode <BEncodedDictionary>(message.Content.Data);
infoHash = InfoHash.FromByteArray((dictionary["infohash"] as BEncodedString).TextBytes);
bitTorrentClientPort = (ushort)((dictionary["bt client port"] as BEncodedNumber).Number);
}
catch (Exception)
{
throw new ArgumentException("附带数据不是用户连接消息数据。");
}
// 这里遇到了一个奇怪的问题，就是编解码的时候
#warning 系统的编解码和网络的编解码字节序可能不同！
// BitConverter 的编解码和网络的编解码顺序可能不同
// 但是奇怪的是，即使这样，KMessage 还能正常解码，地址大多数是正常的，但是端口大多数是不正常的
// 即使是端口，也只是低2字节被颠倒了，高2字节都为零所以无法验证
// 所以目前的临时方法是直接将低2字节颠倒回来，而且只保留低2字节
// 再次测试后发现似乎是 μTorrent 自己的诈和……（以前）第一次收到的是错误的（后来在调试的时候，第一次好像也对了），接下来收到的都是正确的……
//var b1 = (byte)((bitTorrentClientPort & 0x0000ff00) >> 8);
//var b2 = (byte)(bitTorrentClientPort & 0x000000ff);
//bitTorrentClientPort = (int)(((int)b2 << 8) + b1);
}
/// <summary>
/// 解码连接到接入点时收到的字节数组，并应用这些信息。
/// </summary>
/// <param name="data">收到的数据。</param>
///// <param name="sendPeerEnter">解码过程中是否应该广播 PeerEnterNetwork 消息。</param>
/// <exception cref="System.FormatException">解码失败时发生。</exception>
/// <remarks>
/// 需要发送 PeerEnterNetwork 消息的情况会发生于：A开启客户端和μT，B开启客户端和μT，A（用户列表非空）再尝试连接B，此时如果B并没有保存全网的用户列表，那么A就要广播 PeerEnterNetwork。
/// </remarks>
private void DecodeTargetInformation(byte[] data)
{
// 如果对方发过来的是空，那么就肯定不会有数据啦
if (data.Length > 0)
{
BEncodedDictionary dictionary = BEncodedDictionary.Decode(data) as BEncodedDictionary;
if (dictionary == null)
{
throw new FormatException("无法解码。");
}
BEncodedList connList = dictionary["connections"] as BEncodedList;
BEncodedDictionary peersDict = dictionary["peers"] as BEncodedDictionary;
// 规范 v1.2
// 先确认自己，同时 if ... 是兼容老版的通信
if (dictionary.ContainsKey("your endpoint"))
{
BEncodedDictionary yourEndPoint = dictionary["your endpoint"] as BEncodedDictionary;
var ip = new IPAddress((yourEndPoint["ip"] as BEncodedString).TextBytes);
var port = BitConverter.ToUInt16((yourEndPoint["port"] as BEncodedString).TextBytes, 0);
// 分别设置 KClient、TrackerServer 和 BT 客户端的自己
SetLocalEndPoint(new IPEndPoint(ip, port));
TrackerServer.SetLocalEndPoint(new IPEndPoint(ip, TrackerServer.LocalEndPoint.Port));
TrackerServer.SetMyself(new IPEndPoint(ip, TrackerServer.Myself.EndPoint.GetPortNumber()));
this.FreeToGo = true;
TrackerServer.FreeToGo = true;
}
// ...
lock (ConnectionList)
{
foreach (var item in connList)
{
var d = item as BEncodedDictionary;
KEndPoint kep = KEndPoint.Empty;
kep.SetAddress((d["ip"] as BEncodedString).TextBytes);
kep.SetPort((int)BitConverter.ToUInt16((d["port"] as BEncodedString).TextBytes, 0));
try
{
AddToConnectionList(kep);
}
catch (Exception)
{
}
}
}
// 如果已经有用户登记了，那么应该广播
if (TrackerServer.Seeds.Count > 0)
{
lock (TrackerServer.Seeds)
{
foreach (var kv in TrackerServer.Seeds)
{
// 广播消息
BroadcastMyselfAddAsPeer(kv.Key);
}
}
}
lock (TrackerServer.Seeds)
{
foreach (var kv in peersDict)
{
InfoHash infoHash = InfoHash.FromByteArray(kv.Key.TextBytes);
List <Peer> peers = new List <Peer>((kv.Value as BEncodedList).Count);
foreach (var item in (kv.Value as BEncodedList))
{
var d = item as BEncodedDictionary;
KEndPoint kep = KEndPoint.Empty;
kep.SetAddress((d["ip"] as BEncodedString).TextBytes);
kep.SetPort((int)BitConverter.ToUInt16((d["port"] as BEncodedString).TextBytes, 0));
Peer peer = Peer.Create(kep);
peers.Add(peer);
}
try
{
TrackerServer.Seeds.Add(infoHash, peers);
}
catch (Exception)
{
}
}
}
}
else
{
Logger.Log("待解码的数据为空，这意味着对方客户端目前持有的连接列表和用户列表为空。");
}
}
