private static int GetMediaTypeWithQualityLength(
string input,
int start,
out MediaTypeSegmentWithQuality result)
{
result = MediaType.CreateMediaTypeSegmentWithQuality(input, start);
return(result.MediaType.HasValue ? result.MediaType.Length : 0);
}
private static bool TryParseValue(string value, ref int index, out MediaTypeSegmentWithQuality parsedValue)
{
parsedValue = default(MediaTypeSegmentWithQuality);
// The accept 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
// In this case, do not fail parsing in case one of the values is the empty string.
if (string.IsNullOrEmpty(value) || (index == value.Length))
{
return(true);
}
var currentIndex = GetNextNonEmptyOrWhitespaceIndex(value, index, out var separatorFound);
if (currentIndex == value.Length)
{
index = currentIndex;
return(true);
}
// We deliberately want to ignore media types that we are not capable of parsing.
// This is due to the fact that some browsers will send invalid media types like
// ; q=0.9 or */;q=0.2, etc.
// In this scenario, our recovery action consists of advancing the pointer to the
// next separator and moving on.
// In case we don't find the next separator, we simply advance the cursor to the
// end of the string to signal that we are done parsing.
var result = default(MediaTypeSegmentWithQuality);
var length = 0;
try
{
length = GetMediaTypeWithQualityLength(value, currentIndex, out result);
}
catch
{
length = 0;
}
if (length == 0)
{
// The parsing failed.
currentIndex = value.IndexOf(',', currentIndex);
if (currentIndex == -1)
{
index = value.Length;
return(false);
}
index = currentIndex;
return(false);
}
currentIndex = currentIndex + length;
currentIndex = GetNextNonEmptyOrWhitespaceIndex(value, currentIndex, out separatorFound);
// If we've not reached the end of the string, then we must have a separator.
// E. g application/json, text/plain <- We must be at ',' otherwise, we've failed parsing.
if (!separatorFound && (currentIndex < value.Length))
{
index = currentIndex;
return(false);
}
index = currentIndex;
parsedValue = result;
return(true);
}