Esempio n. 1
0
        /// <summary>
        /// Parses the next <see cref="BList"/> from the stream.
        /// </summary>
        /// <param name="stream">The stream to parse from.</param>
        /// <returns>The parsed <see cref="BList"/>.</returns>
        /// <exception cref="InvalidBencodeException{BList}">Invalid bencode</exception>
        public override BList Parse(BencodeStream stream)
        {
            if (stream == null)
            {
                throw new ArgumentNullException(nameof(stream));
            }

            if (stream.Length < MinimumLength)
            {
                throw InvalidBencodeException <BList> .BelowMinimumLength(MinimumLength, stream.Length, stream.Position);
            }

            // Lists must start with 'l'
            if (stream.ReadChar() != 'l')
            {
                throw InvalidBencodeException <BList> .UnexpectedChar('l', stream.ReadPreviousChar(), stream.Position);
            }

            var list = new BList();

            // Loop until next character is the end character 'e' or end of stream
            while (stream.Peek() != 'e' && stream.Peek() != -1)
            {
                // Decode next object in stream
                var bObject = BencodeParser.Parse(stream);
                list.Add(bObject);
            }

            if (stream.ReadChar() != 'e')
            {
                throw InvalidBencodeException <BList> .InvalidEndChar(stream.ReadPreviousChar(), stream.Position);
            }

            return(list);
        }
Esempio n. 2
0
        /// <summary>
        /// Parses the next <see cref="BString"/> from the stream.
        /// </summary>
        /// <param name="stream">The stream to parse from.</param>
        /// <returns>The parsed <see cref="BString"/>.</returns>
        /// <exception cref="InvalidBencodeException{BString}">Invalid bencode</exception>
        /// <exception cref="UnsupportedBencodeException{BString}">The bencode is unsupported by this library</exception>
        public override BString Parse(BencodeStream stream)
        {
            if (stream == null)
            {
                throw new ArgumentNullException(nameof(stream));
            }

            // Minimum valid bencode string is '0:' meaning an empty string
            if (stream.Length < MinimumLength)
            {
                throw InvalidBencodeException <BString> .BelowMinimumLength(MinimumLength, stream.Length, stream.Position);
            }

            var startPosition = stream.Position;

            var lengthString = new StringBuilder();

            for (var c = stream.ReadChar(); c != ':' && c != default(char); c = stream.ReadChar())
            {
                // Because of memory limitations (~1-2 GB) we know for certain we cannot handle more than 10 digits (10GB)
                if (lengthString.Length >= BString.LengthMaxDigits)
                {
                    throw UnsupportedException(
                              $"Length of string is more than {BString.LengthMaxDigits} digits (>10GB) and is not supported (max is ~1-2GB).",
                              startPosition);
                }

                lengthString.Append(c);
            }

            long stringLength;

            if (!ParseUtil.TryParseLongFast(lengthString.ToString(), out stringLength))
            {
                throw InvalidException($"Invalid length '{lengthString}' of string.", startPosition);
            }

            // Int32.MaxValue is ~2GB and is the absolute maximum that can be handled in memory
            if (stringLength > int.MaxValue)
            {
                throw UnsupportedException(
                          $"Length of string is {stringLength:N0} but maximum supported length is {int.MaxValue:N0}.",
                          startPosition);
            }

            var bytes = stream.Read((int)stringLength);

            // If the two don't match we've reached the end of the stream before reading the expected number of chars
            if (bytes.Length != stringLength)
            {
                throw InvalidException(
                          $"Expected string to be {stringLength:N0} bytes long but could only read {bytes.Length:N0} bytes.",
                          startPosition);
            }

            return(new BString(bytes, Encoding));
        }
        /// <summary>
        /// Parses the next <see cref="BDictionary"/> from the stream and its contained keys and values.
        /// </summary>
        /// <param name="stream">The stream to parse from.</param>
        /// <returns>The parsed <see cref="BDictionary"/>.</returns>
        /// <exception cref="InvalidBencodeException{BDictionary}">Invalid bencode</exception>
        public override BDictionary Parse(BencodeStream stream)
        {
            if (stream == null)
            {
                throw new ArgumentNullException(nameof(stream));
            }

            var startPosition = stream.Position;

            if (stream.Length < MinimumLength)
            {
                throw InvalidBencodeException <BDictionary> .BelowMinimumLength(MinimumLength, stream.Length, startPosition);
            }

            // Dictionaries must start with 'd'
            if (stream.ReadChar() != 'd')
            {
                throw InvalidBencodeException <BDictionary> .UnexpectedChar('d', stream.ReadPreviousChar(), startPosition);
            }

            var dictionary = new BDictionary();

            // Loop until next character is the end character 'e' or end of stream
            while (stream.Peek() != 'e' && stream.Peek() != -1)
            {
                BString key;
                try
                {
                    // Decode next string in stream as the key
                    key = BencodeParser.Parse <BString>(stream);
                }
                catch (BencodeException <BString> ex)
                {
                    throw InvalidException("Could not parse dictionary key. Keys must be strings.", ex, startPosition);
                }

                IBObject value;
                try
                {
                    // Decode next object in stream as the value
                    value = BencodeParser.Parse(stream);
                }
                catch (BencodeException ex)
                {
                    throw InvalidException(
                              $"Could not parse dictionary value for the key '{key}'. There needs to be a value for each key.",
                              ex, startPosition);
                }

                if (dictionary.ContainsKey(key))
                {
                    throw InvalidException(
                              $"The dictionary already contains the key '{key}'. Duplicate keys are not supported.", startPosition);
                }

                dictionary.Add(key, value);
            }

            if (stream.ReadChar() != 'e')
            {
                if (stream.EndOfStream)
                {
                    throw InvalidBencodeException <BDictionary> .MissingEndChar();
                }
                throw InvalidBencodeException <BDictionary> .InvalidEndChar(stream.ReadPreviousChar(), stream.Position);
            }

            return(dictionary);
        }
Esempio n. 4
0
        /// <summary>
        /// Parses the next <see cref="BNumber"/> from the stream.
        /// </summary>
        /// <param name="stream">The stream to parse from.</param>
        /// <returns>The parsed <see cref="BNumber"/>.</returns>
        /// <exception cref="InvalidBencodeException{BNumber}">Invalid bencode</exception>
        /// <exception cref="UnsupportedBencodeException{BNumber}">The bencode is unsupported by this library</exception>
        public override BNumber Parse(BencodeStream stream)
        {
            if (stream == null)
            {
                throw new ArgumentNullException(nameof(stream));
            }

            if (stream.Length < MinimumLength)
            {
                throw InvalidBencodeException <BNumber> .BelowMinimumLength(MinimumLength, stream.Length, stream.Position);
            }

            var startPosition = stream.Position;

            // Numbers must start with 'i'
            if (stream.ReadChar() != 'i')
            {
                throw InvalidBencodeException <BNumber> .UnexpectedChar('i', stream.ReadPreviousChar(), stream.Position);
            }

            var  digits = new StringBuilder();
            char c;

            for (c = stream.ReadChar(); c != 'e' && c != default(char); c = stream.ReadChar())
            {
                digits.Append(c);
            }

            // Last read character should be 'e'
            if (c != 'e')
            {
                throw InvalidBencodeException <BNumber> .InvalidEndChar(c, stream.Position);
            }

            var isNegative     = digits[0] == '-';
            var numberOfDigits = isNegative ? digits.Length - 1 : digits.Length;

            // We do not support numbers that cannot be stored as a long (Int64)
            if (numberOfDigits > BNumber.MaxDigits)
            {
                throw UnsupportedException(
                          $"The number '{digits}' has more than 19 digits and cannot be stored as a long (Int64) and therefore is not supported.",
                          startPosition);
            }

            // We need at least one digit
            if (numberOfDigits < 1)
            {
                throw InvalidException("It contains no digits.", startPosition);
            }

            var firstDigit = isNegative ? digits[1] : digits[0];

            // Leading zeros are not valid
            if (firstDigit == '0' && numberOfDigits > 1)
            {
                throw InvalidException($"Leading '0's are not valid. Found value '{digits}'.", startPosition);
            }

            // '-0' is not valid either
            if (firstDigit == '0' && numberOfDigits == 1 && isNegative)
            {
                throw InvalidException("'-0' is not a valid number.", startPosition);
            }

            long number;

            if (!ParseUtil.TryParseLongFast(digits.ToString(), out number))
            {
                var nonSignChars = isNegative ? digits.ToString(1, digits.Length - 1) : digits.ToString();
                if (nonSignChars.Any(x => !x.IsDigit()))
                {
                    throw InvalidException($"The value '{digits}' is not a valid number.", startPosition);
                }

                throw UnsupportedException(
                          $"The value '{digits}' is not a valid long (Int64). Supported values range from '{long.MinValue:N0}' to '{long.MaxValue:N0}'.",
                          startPosition);
            }

            return(new BNumber(number));
        }