/// <summary>
/// Get the single file mode meta information
/// </summary>
/// <param name="rootNode">the root node of torrent</param>
/// <param name="infoNode">the info node of torrent</param>
/// <returns>Return the single file mode meta information</returns>
private static SingleFileMetaInfo GetSingleFileMetaInfo(DictNode rootNode, DictNode infoNode)
{
SingleFileMetaInfo result = new SingleFileMetaInfo();
DecodeRootNode(result, rootNode);
DecodeInfoNode(result, infoNode);
BytesNode nameNode = infoNode["name"] as BytesNode;
Debug.Assert(nameNode != null);
result.Name = nameNode.StringText;
IntNode lengthNode = infoNode["length"] as IntNode;
Debug.Assert(lengthNode != null);
result.Length = lengthNode.Value;
if (infoNode.ContainsKey("md5sum"))
{
BytesNode md5SumNode = infoNode["md5sum"] as BytesNode;
Debug.Assert(md5SumNode != null);
result.Md5Sum = md5SumNode.StringText;
}
else
{
result.Md5Sum = String.Empty;
}
return(result);
}
/// <summary>
/// Node字典类的解码函数
/// </summary>
/// <param name="source">待解码的字节数组</param>
/// <param name="index">字节数组的解码位置</param>
/// <returns>解码的字节数组长度</returns>
public override int Decode(byte[] source, ref int index)
{
//保存初始位置
int start = index;
//跳过字符'd'
index++;
try
{
//当遇到'e'(ASCII码为101),解析结束
while (source[index] != 101)
{
//解析字符串
BytesNode keyNode = new BytesNode();
keyNode.Decode(source, ref index);
if (keyNode.ByteArray.LongLength == 0)
{
throw new BitTorrentException("待添加的字符串长度为0");
}
//解析Handler
BEncodedNode valueNode = BEncodingFactory.Decode(source, ref index);
//'e'(ASCII码为101),解析结束
if (valueNode == null)
{
throw new BitTorrentException("待添加的Handler节点为空");
}
//字典添加key和value
_dict.Add(keyNode.StringText, valueNode);
}
}
//当捕捉IndexOutOfRangeException,抛出BitTorrentException
catch (IndexOutOfRangeException)
{
throw new BitTorrentException("BEncode字典类的字符串长度异常");
}
//当捕捉ArgumentException,抛出BitTorrentException
catch (ArgumentException)
{
throw new BitTorrentException("BEncode字典类中包含相同的字符串关键字");
}
//跳过字符'e'
index++;
//返回所解析的数组长度
return(index - start);
}
/// <summary>
/// Handler字典类的编码函数
/// </summary>
/// <param name="ms">待编码的内存写入流</param>
public override void Encode(MemoryStream ms)
{
//向内存流写入'd'(ASCII码为100)
ms.WriteByte(100);
//对于每一个node进行编码
foreach (string key in _dict.Keys)
{
BytesNode keyNode = new BytesNode(key, Encoding.UTF8);
keyNode.Encode(ms);
_dict[key].Encode(ms);
}
//向内存流写入'e'(ASCII码为101)
ms.WriteByte(101);
}
private static void DecodeInfoNode(MetaInfo metaInfo, DictNode infoNode)
{
IntNode pieceLengthNode = infoNode["piece length"] as IntNode;
Debug.Assert(pieceLengthNode != null);
metaInfo.PieceLength = pieceLengthNode.IntValue;
BytesNode piecesNode = infoNode["pieces"] as BytesNode;
Debug.Assert(piecesNode != null);
metaInfo.SetFullHashValues(piecesNode.ByteArray);
if (infoNode.ContainsKey("private"))
{
IntNode privateNode = infoNode["private"] as IntNode;
Debug.Assert(privateNode != null);
metaInfo.Private = privateNode.Value == 1;
}
}
/// <summary>
/// 解码函数,不带错误判断
/// </summary>
/// <param name="source">待解码的字节数组</param>
/// <param name="position">字节数组的位置</param>
/// <returns>返回Handler基类类型</returns>
public static BEncodedNode Decode(byte[] source, ref int position)
{
byte b = source[position];
BEncodedNode interpreter;
//如果source[position]等于'l'(ASCII码为108),就返回ListHandler
if (b == 108)
{
interpreter = new ListNode();
}
//如果source[position]等于'd'(ASCII码为100),就返回DictionaryHandler
else if (b == 100)
{
interpreter = new DictNode();
}
//如果source[position]等于'index'(ASCII码为105),就返回IntHandler
else if (b == 105)
{
interpreter = new IntNode();
}
//如果source[position]等于'0' - '9'(ASCII码为48 - 57),就返回ByteArrayHandler
else if (b >= 48 && b <= 57)
{
interpreter = new BytesNode();
}
//其它的情况,抛出异常
else
{
throw new BitTorrentException("待解码的字节数组的首位字节异常");
}
interpreter.Decode(source, ref position);
return(interpreter);
}
private static void DecodeRootNode(MetaInfo metaInfo, DictNode rootNode)
{
BytesNode annouceNode = rootNode["announce"] as BytesNode;
Debug.Assert(annouceNode != null);
metaInfo.Announce = annouceNode.StringText;
if (rootNode.ContainsKey("announce-list"))
{
ListNode announceListNode = rootNode["announce-list"] as ListNode;
Debug.Assert(announceListNode != null);
foreach (ListNode announceArrayNode in announceListNode)
{
Debug.Assert(announceArrayNode != null);
IList <string> announceArray = new List <string>();
foreach (BytesNode node in announceArrayNode)
{
Debug.Assert(node != null);
announceArray.Add(node.StringText);
}
metaInfo.AddAnnounceArray(announceArray);
}
}
if (rootNode.ContainsKey("creation date"))
{
IntNode creationDataNode = rootNode["creation date"] as IntNode;
Debug.Assert(creationDataNode != null);
metaInfo.CreationDate = creationDataNode.Value.FromUnixEpochFormat();
}
else
{
metaInfo.CreationDate = new DateTime(1970, 1, 1);
}
if (rootNode.ContainsKey("comment"))
{
BytesNode commentNode = rootNode["comment"] as BytesNode;
Debug.Assert(commentNode != null);
metaInfo.Comment = commentNode.StringText;
}
else
{
metaInfo.Comment = String.Empty;
}
if (rootNode.ContainsKey("created by"))
{
BytesNode createdByNode = rootNode["created by"] as BytesNode;
Debug.Assert(createdByNode != null);
metaInfo.CreatedBy = createdByNode.StringText;
}
else
{
metaInfo.CreatedBy = String.Empty;
}
if (rootNode.ContainsKey("encoding"))
{
BytesNode encodingNode = rootNode["encoding"] as BytesNode;
Debug.Assert(encodingNode != null);
metaInfo.Encoding = encodingNode.StringText;
}
else
{
metaInfo.Encoding = "ASCII";
}
}
/// <summary>
/// Get the multi file mode meta information
/// </summary>
/// <param name="rootNode">the root node of torrent</param>
/// <param name="infoNode">the info node of torrent</param>
/// <returns>Return the multi file mode meta information</returns>
private static MultiFileMetaInfo GetMultiFileMetaInfo(DictNode rootNode, DictNode infoNode)
{
MultiFileMetaInfo result = new MultiFileMetaInfo();
DecodeRootNode(result, rootNode);
DecodeInfoNode(result, infoNode);
BytesNode nameNode = infoNode["name"] as BytesNode;
Debug.Assert(nameNode != null);
result.Name = nameNode.StringText;
ListNode filesNode = infoNode["files"] as ListNode;
Debug.Assert(filesNode != null);
long begin = 0;
FileInfo[] fileInfoArray = new FileInfo[filesNode.Count];
for (int i = 0; i < filesNode.Count; i++)
{
DictNode node = filesNode[i] as DictNode;
IntNode lengthNode = node["length"] as IntNode;
Debug.Assert(lengthNode != null);
FileInfo fileInfo = new FileInfo();
fileInfo.Length = lengthNode.Value;
fileInfo.Begin = begin;
fileInfo.End = begin + fileInfo.Length;
begin = fileInfo.End;
ListNode pathNode = node["path"] as ListNode;
Debug.Assert(pathNode != null);
StringBuilder sb = new StringBuilder();
BytesNode firstPathNode = pathNode[0] as BytesNode;
Debug.Assert(firstPathNode != null);
sb.Append(firstPathNode.StringText);
for (int j = 1; j < pathNode.Count; j++)
{
BytesNode subPathNode = pathNode[j] as BytesNode;
Debug.Assert(subPathNode != null);
sb.AppendFormat(@"\{0}", subPathNode.StringText);
}
fileInfo.Path = sb.ToString();
if (!node.ContainsKey("md5sum"))
{
fileInfo.Md5Sum = String.Empty;
}
else
{
BytesNode md5SumNode = node["md5sum"] as BytesNode;
Debug.Assert(md5SumNode != null);
fileInfo.Md5Sum = md5SumNode.StringText;
}
fileInfoArray[i] = fileInfo;
}
result.SetFileInfoArray(fileInfoArray);
return(result);
}