New: Implemented Torrent Download Clients: uTorrent, Transmission and Deluge. And several public and private Torrent Indexers.

src/MonoTorrent/InfoHash.cs

@@ -0,0 +1,171 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using MonoTorrent.Common;
+using System.Web;
+
+namespace MonoTorrent
+{
+    public class InfoHash : IEquatable <InfoHash>
+    {
+        static Dictionary<char, byte> base32DecodeTable;
+
+        static InfoHash()
+        {
+            base32DecodeTable = new Dictionary<char, byte>();
+            string table = "abcdefghijklmnopqrstuvwxyz234567";
+            for (int i = 0; i < table.Length; i++)
+                base32DecodeTable[table[i]] = (byte)i;
+        }
+
+        byte[] hash;
+
+        internal byte[] Hash
+        {
+            get { return hash; }
+        }
+
+        public InfoHash(byte[] infoHash)
+        {
+            Check.InfoHash(infoHash);
+            if (infoHash.Length != 20)
+                throw new ArgumentException("Infohash must be exactly 20 bytes long");
+            hash = (byte[])infoHash.Clone();
+        }
+
+        public override bool Equals(object obj)
+        {
+            return Equals(obj as InfoHash);
+        }
+
+        public bool Equals(byte[] other)
+        {
+            return other == null || other.Length != 20 ? false : Toolbox.ByteMatch(Hash, other);
+        }
+
+        public bool Equals(InfoHash other)
+        {
+            return this == other;
+        }
+
+        public override int GetHashCode()
+        {
+            // Equality is based generally on checking 20 positions, checking 4 should be enough
+            // for the hashcode as infohashes are randomly distributed.
+            return Hash[0] | (Hash[1] << 8) | (Hash[2] << 16) | (Hash[3] << 24);
+        }
+
+        public byte[] ToArray()
+        {
+            return (byte[])hash.Clone();
+        }
+
+        public string ToHex()
+        {
+            StringBuilder sb = new StringBuilder(40);
+            for (int i = 0; i < hash.Length; i++)
+            {
+                string hex = hash[i].ToString("X");
+                if (hex.Length != 2)
+                    sb.Append("0");
+                sb.Append(hex);
+            }
+            return sb.ToString();
+        }
+
+        public override string ToString()
+        {
+            return BitConverter.ToString(hash);
+        }
+
+        public string UrlEncode()
+        {
+            return UriHelper.UrlEncode(Hash);
+        }
+
+        public static bool operator ==(InfoHash left, InfoHash right)
+        {
+            if ((object)left == null)
+                return (object)right == null;
+            if ((object)right == null)
+                return false;
+            return Toolbox.ByteMatch(left.Hash, right.Hash);
+        }
+
+        public static bool operator !=(InfoHash left, InfoHash right)
+        {
+            return !(left == right);
+        }
+
+        public static InfoHash FromBase32(string infoHash)
+        {
+            Check.InfoHash (infoHash);
+            if (infoHash.Length != 32)
+                throw new ArgumentException("Infohash must be a base32 encoded 32 character string");
+            
+            infoHash = infoHash.ToLower();
+            int infohashOffset =0 ;
+            byte[] hash = new byte[20];
+            var temp = new byte[8];
+            for (int i = 0; i < hash.Length; ) {
+                for (int j=0; j < 8; j++)
+                    if (!base32DecodeTable.TryGetValue(infoHash[infohashOffset++], out temp[j]))
+                        throw new ArgumentException ("infoHash", "Value is not a valid base32 encoded string");
+
+                //8 * 5bits = 40 bits = 5 bytes
+                hash[i++] = (byte)((temp[0] << 3) | (temp [1]>> 2));
+                hash[i++] = (byte)((temp[1] << 6) | (temp[2] << 1) | (temp[3] >> 4));
+                hash[i++] = (byte)((temp[3] << 4) | (temp [4]>> 1));
+                hash[i++] = (byte)((temp[4] << 7) | (temp[5] << 2) | (temp [6]>> 3));
+                hash[i++] = (byte)((temp[6] << 5) | temp[7]);
+            }
+
+            return new InfoHash(hash);
+        }
+
+        public static InfoHash FromHex(string infoHash)
+        {
+            Check.InfoHash (infoHash);
+            if (infoHash.Length != 40)
+                throw new ArgumentException("Infohash must be 40 characters long");
+            
+            byte[] hash = new byte[20];
+            for (int i = 0; i < hash.Length; i++)
+                hash[i] = byte.Parse(infoHash.Substring(i * 2, 2), System.Globalization.NumberStyles.HexNumber);
+
+            return new InfoHash(hash);
+        }
+
+        public static InfoHash FromMagnetLink(string magnetLink)
+        {
+            Check.MagnetLink(magnetLink);
+            if (!magnetLink.StartsWith("magnet:?"))
+                throw new ArgumentException("Invalid magnet link format");
+            magnetLink = magnetLink.Substring("magnet:?".Length);
+            int hashStart = magnetLink.IndexOf("xt=urn:btih:");
+            if (hashStart == -1)
+                throw new ArgumentException("Magnet link does not contain an infohash");
+            hashStart += "xt=urn:btih:".Length;
+
+            int hashEnd = magnetLink.IndexOf('&', hashStart);
+            if (hashEnd == -1)
+                hashEnd = magnetLink.Length;
+
+            switch (hashEnd - hashStart)
+            {
+                case 32:
+                    return FromBase32(magnetLink.Substring(hashStart, 32));
+                case 40:
+                    return FromHex(magnetLink.Substring(hashStart, 40));
+                default:
+                    throw new ArgumentException("Infohash must be base32 or hex encoded.");
+            }
+        }
+
+        public static InfoHash UrlDecode(string infoHash)
+        {
+            Check.InfoHash(infoHash);
+            return new InfoHash(UriHelper.UrlDecode(infoHash));
+        }
+    }
+}