/// <summary>
/// Decodes a BEncodedString from the supplied StreamReader
/// </summary>
/// <param name="reader">The StreamReader containing the BEncodedString</param>
internal override void DecodeInternal(RawReader reader)
{
if (reader == null)
{
throw new ArgumentNullException("reader");
}
int letterCount;
string length = string.Empty;
while ((reader.PeekByte() != -1) && (reader.PeekByte() != ':')) // read in how many characters
{
length += (char)reader.ReadByte(); // the string is
}
if (reader.ReadByte() != ':') // remove the ':'
{
throw new BEncodingException("Invalid data found. Aborting");
}
if (!int.TryParse(length, out letterCount))
{
throw new BEncodingException(string.Format("Invalid BEncodedString. Length was '{0}' instead of a number", length));
}
this.textBytes = new byte[letterCount];
if (reader.Read(textBytes, 0, letterCount) != letterCount)
{
throw new BEncodingException("Couldn't decode string");
}
}
/// <summary>
/// Special decoding method for torrent files - allows dictionary attributes to be out of order for the
/// overall torrent file, but imposes strict rules on the info dictionary.
/// </summary>
/// <returns></returns>
public static BEncodedDictionary DecodeTorrent(RawReader reader)
{
BEncodedString key = null;
BEncodedValue value = null;
var torrent = new BEncodedDictionary();
if (reader.ReadByte() != 'd')
{
throw new BEncodingException("Invalid data found. Aborting"); // Remove the leading 'd'
}
while ((reader.PeekByte() != -1) && (reader.PeekByte() != 'e'))
{
key = (BEncodedString)Decode(reader); // keys have to be BEncoded strings
if (reader.PeekByte() == 'd')
{
value = new BEncodedDictionary();
((BEncodedDictionary)value).DecodeInternal(reader, key.Text.ToLower().Equals("info"));
}
else
{
value = Decode(reader); // the value is a BEncoded value
}
torrent.dictionary.Add(key, value);
}
if (reader.ReadByte() != 'e') // remove the trailing 'e'
{
throw new BEncodingException("Invalid data found. Aborting");
}
return(torrent);
}
private void DecodeInternal(RawReader reader, bool strictDecoding)
{
BEncodedString key = null;
BEncodedValue value = null;
BEncodedString oldkey = null;
if (reader.ReadByte() != 'd')
{
throw new BEncodingException("Invalid data found. Aborting"); // Remove the leading 'd'
}
while ((reader.PeekByte() != -1) && (reader.PeekByte() != 'e'))
{
key = (BEncodedString)BEncodedValue.Decode(reader); // keys have to be BEncoded strings
if (oldkey != null && oldkey.CompareTo(key) > 0)
{
if (strictDecoding)
{
throw new BEncodingException(String.Format(
"Illegal BEncodedDictionary. The attributes are not ordered correctly. Old key: {0}, New key: {1}",
oldkey, key));
}
}
oldkey = key;
value = BEncodedValue.Decode(reader); // the value is a BEncoded value
dictionary.Add(key, value);
}
if (reader.ReadByte() != 'e') // remove the trailing 'e'
{
throw new BEncodingException("Invalid data found. Aborting");
}
}
static BEncodedNumber DecodeNumber(RawReader reader)
{
int sign = 1;
long result = 0;
int val = reader.ReadByte();
if (val == '-')
{
sign = -1;
val = reader.ReadByte();
}
do
{
if (val < '0' || val > '9')
{
throw new BEncodingException("Invalid number found.");
}
result = result * 10 + (val - '0');
} while ((val = reader.ReadByte()) != 'e' && val != -1);
if (val == -1) //remove the trailing 'e'
{
throw new BEncodingException("Invalid data found. Aborting.");
}
result *= sign;
return(result);
}
internal static BEncodedDictionary DecodeTorrent(RawReader reader)
{
var torrent = new BEncodedDictionary();
if (reader.ReadByte() != 'd')
{
throw new BEncodingException("Invalid data found. Aborting"); // Remove the leading 'd'
}
int read;
while ((read = reader.ReadByte()) != -1 && read != 'e')
{
BEncodedValue value;
var key = (BEncodedString)Decode(reader, read); // keys have to be BEncoded strings
if ((read = reader.ReadByte()) == 'd')
{
value = DecodeDictionary(reader, InfoKey.Equals(key));
}
else
{
value = Decode(reader, read); // the value is a BEncoded value
}
torrent.Add(key, value);
}
if (read != 'e') // remove the trailing 'e'
{
throw new BEncodingException("Invalid data found. Aborting");
}
return(torrent);
}
/// <summary>
/// Decodes a BEncodedList from the given StreamReader
/// </summary>
/// <param name="reader"></param>
internal override void DecodeInternal(RawReader reader)
{
try
{
if (reader.ReadByte() != 'l') // Remove the leading 'l'
{
throw new BEncodingException("Invalid data found. Aborting");
}
while ((reader.PeekChar() != -1) && ((char)reader.PeekChar() != 'e'))
{
list.Add(BEncodedValue.Decode(reader));
}
if (reader.ReadByte() != 'e') // Remove the trailing 'e'
{
throw new BEncodingException("Invalid data found. Aborting");
}
}
catch (BEncodingException ex)
{
throw new BEncodingException("Couldn't decode list", ex);
}
catch
{
throw new BEncodingException("Couldn't decode list");
}
}
internal static (BEncodedDictionary torrent, InfoHash infohash) DecodeTorrent(RawReader reader)
{
var torrent = new BEncodedDictionary();
if (reader.ReadByte() != 'd')
{
throw new BEncodingException("Invalid data found. Aborting"); // Remove the leading 'd'
}
int read;
InfoHash infoHash = null;
// We can save a few resizes and array copies if we pre-allocate
// a buffer and then get the memory stream to write to it. We
// can trivially pass the final set of bytes to the hash function then.
byte[] capturedDataBytes = null;
MemoryStream capturedDataStream = null;
while ((read = reader.ReadByte()) != -1 && read != 'e')
{
BEncodedValue value;
var key = (BEncodedString)Decode(reader, read); // keys have to be BEncoded strings
if ((read = reader.ReadByte()) == 'd')
{
if (InfoKey.Equals(key))
{
capturedDataBytes = new byte[reader.Length - reader.Position];
capturedDataStream = new MemoryStream(capturedDataBytes, true);
capturedDataStream.WriteByte((byte)'d');
reader.BeginCaptureData(capturedDataStream);
}
value = DecodeDictionary(reader, reader.StrictDecoding);
if (InfoKey.Equals(key))
{
reader.EndCaptureData();
using var hasher = SHA1.Create();
infoHash = new InfoHash(hasher.ComputeHash(capturedDataBytes, 0, (int)capturedDataStream.Position));
}
}
else
{
value = Decode(reader, read); // the value is a BEncoded value
}
torrent.Add(key, value);
}
if (read != 'e') // remove the trailing 'e'
{
throw new BEncodingException("Invalid data found. Aborting");
}
return(torrent, infoHash);
}
/// <summary>
/// Decodes a BEncoded number from the supplied RawReader
/// </summary>
/// <param name="reader">RawReader containing a BEncoded Number</param>
internal override void DecodeInternal(RawReader reader)
{
var sign = 1;
if (reader == null)
{
throw new ArgumentNullException("reader");
}
try
{
if (reader.ReadByte() != 'i') // remove the leading 'i'
{
throw new BEncodingException("Invalid data found. Aborting.");
}
if (reader.PeekChar() == '-')
{
sign = -1;
reader.ReadChar();
}
int letter;
while (((letter = reader.PeekChar()) != -1) && letter != 'e')
{
if (letter < '0' || letter > '9')
{
throw new BEncodingException("Invalid number found.");
}
number = number * 10 + (letter - '0');
reader.ReadChar();
}
if (reader.ReadByte() != 'e') //remove the trailing 'e'
{
throw new BEncodingException("Invalid data found. Aborting.");
}
number *= sign;
}
catch (BEncodingException ex)
{
throw new BEncodingException("Couldn't decode number", ex);
}
catch
{
throw new BEncodingException("Couldn't decode number");
}
}
static BEncodedString DecodeString(RawReader reader, int length)
{
int read;
while ((read = reader.ReadByte()) != -1 && read != ':')
{
if (read < '0' || read > '9')
{
throw new BEncodingException($"Invalid BEncodedString. Length was '{length}' instead of a number");
}
length = length * 10 + (read - '0');
}
if (read != ':')
{
throw new BEncodingException("Invalid data found. Aborting");
}
var bytes = new byte[length];
if (reader.Read(bytes, 0, length) != length)
{
throw new BEncodingException("Couldn't decode string");
}
return(new BEncodedString(bytes));
}
static BEncodedDictionary DecodeDictionary(RawReader reader, bool strictDecoding)
{
int read;
BEncodedString oldkey = null;
var dictionary = new BEncodedDictionary();
while ((read = reader.ReadByte()) != -1 && read != 'e')
{
BEncodedString key = DecodeString(reader, read - '0'); // keys have to be BEncoded strings
if (oldkey != null && oldkey.CompareTo(key) > 0)
{
if (strictDecoding)
{
throw new BEncodingException(
$"Illegal BEncodedDictionary. The attributes are not ordered correctly. Old key: {oldkey}, New key: {key}");
}
}
oldkey = key;
BEncodedValue value = Decode(reader); // the value is a BEncoded value
dictionary.Add(key, value);
}
if (read != 'e') // remove the trailing 'e'
{
throw new BEncodingException("Invalid data found. Aborting");
}
return(dictionary);
}
/// <summary>
/// Special decoding method for torrent files - allows dictionary attributes to be out of order for the
/// overall torrent file, but imposes strict rules on the info dictionary.
/// </summary>
/// <returns></returns>
public static BEncodedDictionary DecodeTorrent(RawReader reader)
{
BEncodedString key = null;
BEncodedValue value = null;
BEncodedDictionary torrent = new BEncodedDictionary();
try
{
if (reader.ReadByte() != 'd')
{
throw new BEncodingException("Invalid data found. Aborting"); // Remove the leading 'd'
}
while ((reader.PeekChar() != -1) && ((char)reader.PeekChar() != 'e'))
{
key = (BEncodedString)BEncodedValue.Decode(reader); // keys have to be BEncoded strings
if (reader.PeekChar() == 'd')
{
value = new BEncodedDictionary();
if (key.Text.ToLower().Equals("info"))
{
((BEncodedDictionary)value).DecodeInternal(reader, true);
}
else
{
((BEncodedDictionary)value).DecodeInternal(reader, false);
}
}
else
{
value = BEncodedValue.Decode(reader); // the value is a BEncoded value
}
torrent.dictionary.Add(key, value);
}
if (reader.ReadByte() != 'e') // remove the trailing 'e'
{
throw new BEncodingException("Invalid data found. Aborting");
}
return(torrent);
}
catch (Exception ex)
{
throw new BEncodingException("Couldn't decode dictionary", ex);
}
}
/// <summary>
/// Decodes a BEncodedList from the given StreamReader
/// </summary>
/// <param name="reader"></param>
internal override void DecodeInternal(RawReader reader)
{
if (reader.ReadByte() != 'l') // Remove the leading 'l'
{
throw new BEncodingException("Invalid data found. Aborting");
}
while ((reader.PeekByte() != -1) && (reader.PeekByte() != 'e'))
{
list.Add(BEncodedValue.Decode(reader));
}
if (reader.ReadByte() != 'e') // Remove the trailing 'e'
{
throw new BEncodingException("Invalid data found. Aborting");
}
}
static BEncodedList DecodeList(RawReader reader)
{
var list = new BEncodedList();
int read;
while ((read = reader.ReadByte()) != -1 && read != 'e')
{
list.Add(Decode(reader, read));
}
if (read != 'e') // Remove the trailing 'e'
{
throw new BEncodingException("Invalid data found. Aborting");
}
return(list);
}
internal static BEncodedValue Decode(RawReader reader) => Decode(reader, reader.ReadByte());