银河星尘

#define _GNU_SOURCE	// 没这个编译时会有warning, 详见下文
#include <stdio .h>
 
ssize_t getline(char **lineptr, size_t *n, FILE *stream);
ssize_t getdelim(char **lineptr, size_t *n, int delim, FILE *stream);
</stdio>

    //013231原創,u2.dmhy.org首發,轉載或使用需注明出處.
    class Torrent
    {
        public Torrent(string filename)
        {
            this.filename = filename;
            using (FileStream fs = new FileStream(filename, FileMode.Open, FileAccess.Read))
            {
                bencodeArray = new byte[fs.Length];
                fs.Read(bencodeArray, 0, (int)fs.Length);
            }
            curIndex = 0;
            rootDictionary = scan() as Dictionary<string ,object>;
            files = getFiles();
        }
 
        object scan()
        {
            switch ((char)bencodeArray[curIndex])
            {
                case '0':
                case '1':
                case '2':
                case '3':
                case '4':
                case '5':
                case '6':
                case '7':
                case '8':
                case '9':
                    return string_b();
                case 'i':
                    return integer_b();
                case 'l':
                    return list_b();
                case 'd':
                    return dictionary_b();
                default:
                    throw (new Exception("文件結構錯誤."));
            }
        }
 
        string string_b()
        {
            int length = (int)extraction_integer();
            match(':');
            if (curKey != "pieces")
            {
                UTF8Encoding utf8Encoding = new UTF8Encoding();
                curIndex += length;
                return utf8Encoding.GetString(bencodeArray, curIndex-length, length);
            }
            else
            {
                StringBuilder hashSB = new StringBuilder();
                for (int i = 0; i != length; ++i)
                    hashSB.Append(bencodeArray[curIndex++].ToString("X2"));
                return hashSB.ToString();
            }
        }
 
        long integer_b()
        {
            match('i');
            long i = extraction_integer();
            match('e');
            return i;
        }
 
        List<object> list_b()
        {
            match('l');
            List</object><object> list = new List</object><object>();
            while (bencodeArray[curIndex] != 'e')
                list.Add(scan());
            match('e');
            return list;
        }
 
        Dictionary<string ,object> dictionary_b()
        {
            match('d');
            Dictionary</string><string , object> dic = new Dictionary</string><string , object>();
            while (bencodeArray[curIndex] != 'e')
            {
                curKey = string_b();
                dic[curKey] = scan();
                curKey = "";
            }
            match('e');
            return dic;
        }
 
        long extraction_integer()
        {
            StringBuilder intSB = new StringBuilder();
            while ('0'< =bencodeArray[curIndex] && bencodeArray[curIndex] <= '9' || bencodeArray[curIndex]=='-')
                intSB.Append((char)bencodeArray[curIndex++]);
            return long.Parse(intSB.ToString());
        }
 
        void match(char c)
        {
            if (bencodeArray[curIndex++] != c)
                throw (new Exception("文件結構錯誤."));
        }
 
        List<FileInTorrent> getFiles()
        {
            Dictionary</string><string , object> info = rootDictionary["info"] as Dictionary</string><string , object>;
            if (info.ContainsKey("files"))
            {
                List<fileintorrent> files = new List</fileintorrent><fileintorrent>();
                List<object> fileList = info["files"] as List</object><object>;
                foreach (Dictionary<string , object> file in fileList)
                {
                    List<object> pathList = file["path"] as List</object><object>;
                    string path = "";
                    foreach (string s in pathList)
                        path += "\\"+s;
                    files.Add(new FileInTorrent(path, (long)file["length"]));
                }
                return files;
            }
            else
            {
                List<fileintorrent> files = new List</fileintorrent><fileintorrent>();
                files.Add(new FileInTorrent(info["name"] as string, (long)info["length"]));
                return files;
            }
        }
 
        public string Announce
        {
            get { return rootDictionary["announce"] as string; }
        }
 
        public string CreatedBy
        {
            get { return rootDictionary["created by"] as string; }
        }
 
        public DateTime CreationDate
        {
            get { return new DateTime(1970, 1, 1, 0, 0, 0).AddSeconds((long)rootDictionary["creation date"]); }
        }
 
        public string Encoding
        {
            get { return rootDictionary["encoding"] as string; }
        }
 
        public long PieceLength
        {
            get { return (long)(rootDictionary["info"] as Dictionary<string ,object>)["piece length"]; }
        }
 
        public string Pieces
        {
            get { return (string)(rootDictionary["info"] as Dictionary</string><string , object>)["pieces"]; }
        }
 
        public List<fileintorrent> Files
        {
            get { return files; }
        }
 
        public bool Private
        {
            get
            {
                if ((rootDictionary["info"] as Dictionary<string ,object>).ContainsKey("private"))
                    return (long)(rootDictionary["info"] as Dictionary</string><string , object>)["private"] == 1;
                else
                    return false;
            }
        }
 
        string filename;
        int curIndex;
        string curKey;
        byte[] bencodeArray;
        Dictionary</string><string , object> rootDictionary;
        List<fileintorrent> files;
    }
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