// Returns the length of a range list. E.g. "1-2, 3-4, 5-6" adds 3 ranges to 'rangeCollection'. Note that empty
// list segments are allowed, e.g. ",1-2, , 3-4,,".
internal static int GetRangeItemListLength(
StringSegment input,
int startIndex,
ICollection <RangeItemHeaderValue> rangeCollection)
{
Contract.Requires(rangeCollection != null);
Contract.Requires(startIndex >= 0);
Contract.Ensures((Contract.Result <int>() == 0) || (rangeCollection.Count > 0),
"If we can parse the string, then we expect to have at least one range item.");
if ((StringSegment.IsNullOrEmpty(input)) || (startIndex >= input.Length))
{
return(0);
}
// Empty segments are allowed, so skip all delimiter-only segments (e.g. ", ,").
var separatorFound = false;
var current = HeaderUtilities.GetNextNonEmptyOrWhitespaceIndex(input, startIndex, true, out separatorFound);
// It's OK if we didn't find leading separator characters. Ignore 'separatorFound'.
if (current == input.Length)
{
return(0);
}
RangeItemHeaderValue range = null;
while (true)
{
var rangeLength = GetRangeItemLength(input, current, out range);
if (rangeLength == 0)
{
return(0);
}
rangeCollection.Add(range);
current = current + rangeLength;
current = HeaderUtilities.GetNextNonEmptyOrWhitespaceIndex(input, current, true, out separatorFound);
// If the string is not consumed, we must have a delimiter, otherwise the string is not a valid
// range list.
if ((current < input.Length) && !separatorFound)
{
return(0);
}
if (current == input.Length)
{
return(current - startIndex);
}
}
}
public sealed override bool TryParseValue(StringSegment value, ref int index, [MaybeNull] out T parsedValue)
{
parsedValue = default;
// If multiple values are supported (i.e. list of values), then accept an empty string: The header may
// be added multiple times to the request/response message. E.g.
// Accept: text/xml; q=1
// Accept:
// Accept: text/plain; q=0.2
if (StringSegment.IsNullOrEmpty(value) || (index == value.Length))
{
return(SupportsMultipleValues);
}
var separatorFound = false;
var current = HeaderUtilities.GetNextNonEmptyOrWhitespaceIndex(value, index, SupportsMultipleValues,
out separatorFound);
if (separatorFound && !SupportsMultipleValues)
{
return(false); // leading separators not allowed if we don't support multiple values.
}
if (current == value.Length)
{
if (SupportsMultipleValues)
{
index = current;
}
return(SupportsMultipleValues);
}
T result;
var length = GetParsedValueLength(value, current, out result);
if (length == 0)
{
return(false);
}
current = current + length;
current = HeaderUtilities.GetNextNonEmptyOrWhitespaceIndex(value, current, SupportsMultipleValues,
out separatorFound);
// If we support multiple values and we've not reached the end of the string, then we must have a separator.
if ((separatorFound && !SupportsMultipleValues) || (!separatorFound && (current < value.Length)))
{
return(false);
}
index = current;
parsedValue = result;
return(true);
}
private static bool TrySetOptionalTokenList(
NameValueHeaderValue nameValue,
ref bool boolField,
ref ICollection <StringSegment> destination)
{
Contract.Requires(nameValue != null);
if (nameValue.Value == null)
{
boolField = true;
return(true);
}
// We need the string to be at least 3 chars long: 2x quotes and at least 1 character. Also make sure we
// have a quoted string. Note that NameValueHeaderValue will never have leading/trailing whitespaces.
var valueString = nameValue.Value;
if ((valueString.Length < 3) || (valueString[0] != '\"') || (valueString[valueString.Length - 1] != '\"'))
{
return(false);
}
// We have a quoted string. Now verify that the string contains a list of valid tokens separated by ','.
var current = 1; // skip the initial '"' character.
var maxLength = valueString.Length - 1; // -1 because we don't want to parse the final '"'.
var separatorFound = false;
var originalValueCount = destination == null ? 0 : destination.Count;
while (current < maxLength)
{
current = HeaderUtilities.GetNextNonEmptyOrWhitespaceIndex(valueString, current, true,
out separatorFound);
if (current == maxLength)
{
break;
}
var tokenLength = HttpRuleParser.GetTokenLength(valueString, current);
if (tokenLength == 0)
{
// We already skipped whitespaces and separators. If we don't have a token it must be an invalid
// character.
return(false);
}
if (destination == null)
{
destination = new ObjectCollection <StringSegment>(CheckIsValidTokenAction);
}
destination.Add(valueString.Subsegment(current, tokenLength));
current = current + tokenLength;
}
// After parsing a valid token list, we expect to have at least one value
if ((destination != null) && (destination.Count > originalValueCount))
{
boolField = true;
return(true);
}
return(false);
}