/// <summary>Builds a Content-Type header which includes media type and encoding information.</summary>
/// <param name="mediaType">Media type to be used.</param>
/// <param name="encoding">Encoding to be used in response, possibly null.</param>
/// <returns>The value for the Content-Type header.</returns>
internal static string BuildContentType(MediaType mediaType, Encoding encoding)
{
DebugUtils.CheckNoExternalCallers();
Debug.Assert(mediaType != null, "mediaType != null");
string mediaTypeAsText = mediaType.ToText();
if (encoding == null)
{
return mediaTypeAsText;
}
else
{
return string.Concat(mediaTypeAsText, ";", HttpConstants.Charset, "=", encoding.WebName);
}
}
/// <summary>
/// Gets a number of non-* matching type name parts and parameters; returns the number of matching type name parts or -1 if not matching at all.
/// The <paramref name="matchingParameters"/> represent the number of matched parameters or -1 if there are no parameters to match and the candidate
/// type also has no parameters.
/// </summary>
/// <param name="candidate">Candidate media type to match.</param>
/// <param name="matchingParameters">The number of matched parameters or -1 if there are no parameters to match and the <paramref name="candidate"/> does not have parameters either.</param>
/// <param name="qualityValue">The quality value of the candidate (or -1 if none is specified).</param>
/// <param name="parameterCount">The number of parameters of this type that are not accept-parameters (and thus ignored).</param>
/// <returns>Returns the number of matching type name parts or -1 if not matching at all. The <paramref name="matchingParameters"/>
/// represent the number of matched parameters or -1 if there are no parameters to match and the candidate
/// type also has no parameters.
/// </returns>
internal int GetMatchingParts(MediaType candidate, out int matchingParameters, out int qualityValue, out int parameterCount)
{
DebugUtils.CheckNoExternalCallers();
Debug.Assert(candidate != null, "candidate must not be null.");
int matchedNameParts = -1;
if (this.type == "*")
{
matchedNameParts = 0;
}
else
{
if (HttpUtils.CompareMediaTypeNames(this.type, candidate.type))
{
if (this.subType == "*")
{
// only type matches
matchedNameParts = 1;
}
else if (HttpUtils.CompareMediaTypeNames(this.subType, candidate.subType))
{
// both type and subtype match
matchedNameParts = 2;
}
}
}
qualityValue = DefaultQualityValue;
parameterCount = 0;
matchingParameters = 0;
// NOTE: we know that the candidates don't have accept parameters so we can rely
// on the total parameter count.
IList<KeyValuePair<string, string>> candidateParameters = candidate.Parameters;
bool candidateHasParams = candidateParameters != null && candidateParameters.Count > 0;
bool thisHasParams = this.parameters != null && this.parameters.Count > 0;
if (thisHasParams)
{
for (int i = 0; i < this.parameters.Count; ++i)
{
string parameterName = this.parameters[i].Key;
if (IsQualityValueParameter(parameterName))
{
// once we hit the q-value in the parameters we know that only accept-params will follow
// that don't contribute to the matching. Parse the quality value but don't continue processing
// parameters.
qualityValue = ParseQualityValue(this.parameters[i].Value.Trim());
break;
}
parameterCount = i + 1;
if (candidateHasParams)
{
// find the current parameter name in the set of parameters of the candidate and compare the value;
// if they match increase the result count
string parameterValue;
if (TryFindMediaTypeParameter(candidateParameters, parameterName, out parameterValue) &&
string.Compare(this.parameters[i].Value.Trim(), parameterValue.Trim(), StringComparison.OrdinalIgnoreCase) == 0)
{
matchingParameters++;
}
}
}
}
// if we have no non-accept parameters special rules apply
if (!thisHasParams || parameterCount == 0)
{
if (candidateHasParams)
{
if (matchedNameParts == 0 || matchedNameParts == 1)
{
// this is a media range specification using the '*' wildcard.
// we assume that all parameters are matched for such ranges so the server
// will pick the most specific one
matchingParameters = candidateParameters.Count;
}
else
{
// the candidate type has parameters while this type has not;
// return 0 to indicate that none of the candidate's parameters match.
matchingParameters = 0;
}
}
else
{
// neither this type nor the candidate have parameters; in this case we return -1 to indicate
// that the candidate parameters are a perfect.
matchingParameters = -1;
}
}
return matchedNameParts;
}
/// <summary>Gets the best encoding available for the specified charset request.</summary>
/// <param name="acceptableCharsets">
/// The Accept-Charset header value (eg: "iso-8859-5, unicode-1-1;q=0.8").
/// </param>
/// <param name="mediaType">The media type used to compute the default encoding for the payload.</param>
/// <param name="utf8Encoding">The encoding to use for UTF-8 charsets; we use the one without the BOM.</param>
/// <param name="defaultEncoding">The encoding to use if no encoding could be computed from the <paramref name="acceptableCharsets"/> or <paramref name="mediaType"/>.</param>
/// <returns>An Encoding object appropriate to the specifed charset request.</returns>
internal static Encoding EncodingFromAcceptableCharsets(string acceptableCharsets, MediaType mediaType, Encoding utf8Encoding, Encoding defaultEncoding)
{
DebugUtils.CheckNoExternalCallers();
Debug.Assert(mediaType != null, "mediaType != null");
// Determines the appropriate encoding mapping according to
// RFC 2616.14.2 (http://tools.ietf.org/html/rfc2616#section-14.2).
Encoding result = null;
if (!string.IsNullOrEmpty(acceptableCharsets))
{
// PERF: in the future if we find that computing the encoding from the accept charsets is
// too expensive we could introduce a cache of original strings to resolved encoding.
List<CharsetPart> parts = new List<CharsetPart>(AcceptCharsetParts(acceptableCharsets));
parts.Sort(delegate(CharsetPart x, CharsetPart y)
{
return y.Quality - x.Quality;
});
foreach (CharsetPart part in parts)
{
if (part.Quality > 0)
{
// When UTF-8 is specified, select the version that doesn't use the BOM.
if (String.Compare("utf-8", part.Charset, StringComparison.OrdinalIgnoreCase) == 0)
{
result = utf8Encoding;
break;
}
else
{
result = GetEncodingFromCharsetName(part.Charset);
if (result != null)
{
break;
}
// If the charset is not supported it is ignored so other possible charsets are evaluated.
}
}
}
}
// No Charset was specifed, or if charsets were specified, no valid charset was found.
// Returning a different charset is also valid. Get the default encoding for the media type.
if (result == null)
{
result = mediaType.SelectEncoding();
if (result == null)
{
return defaultEncoding;
}
}
return result;
}
/// <summary>
/// Parses the accepted charsets and matches them against the supported encodings for the given <paramref name="payloadKind"/>.
/// </summary>
/// <param name="acceptCharsetHeader">The Accept-Charset header of the request.</param>
/// <param name="payloadKind">The <see cref="ODataPayloadKind"/> for which to compute the encoding.</param>
/// <param name="mediaType">The media type used to compute the default encoding for the payload.</param>
/// <returns>The encoding to be used for the response.</returns>
private static Encoding GetEncoding(string acceptCharsetHeader, ODataPayloadKind payloadKind, MediaType mediaType)
{
if (payloadKind == ODataPayloadKind.BinaryValue)
{
return null;
}
else
{
// TODO: we currently assume that the media type does not have a 'charset' parameter specified. This is true for
// the current uses of this method. Consider making this general purpose and also include the 'charset'
// parameter on the media type into the resolution process. (Currently the media type is only used to
// compute the default encoding).
return HttpUtils.EncodingFromAcceptableCharsets(acceptCharsetHeader, mediaType, encodingUtf8NoPreamble, encodingUtf8NoPreamble);
}
}
/// <summary>
/// Given the Accept and the Accept-Charset headers of the request message computes the media type, encoding and <see cref="ODataFormat"/>
/// to be used for the response message.
/// </summary>
/// <param name="settings">The writer settings to use for serializing the response payload.</param>
/// <param name="payloadKind">The kind of payload to be serialized as part of the response message.</param>
/// <param name="mediaType">The media type to be used in the response message.</param>
/// <param name="encoding">The encoding to be used in the response message.</param>
/// <returns>The <see cref="ODataFormat"/> used when serializing the response.</returns>
internal static ODataFormat GetContentTypeFromSettings(
ODataWriterSettings settings,
ODataPayloadKind payloadKind,
out MediaType mediaType,
out Encoding encoding)
{
DebugUtils.CheckNoExternalCallers();
Debug.Assert(settings != null, "settings != null");
// compute format, media type and encoding
ODataFormat format;
if (settings.AcceptableMediaTypes != null)
{
mediaType = GetMediaType(settings.AcceptableMediaTypes, payloadKind, out format);
encoding = GetEncoding(settings.AcceptableCharsets, payloadKind, mediaType);
}
else
{
mediaType = GetDefaultMediaType(payloadKind, settings.Format, out format);
encoding = mediaType.SelectEncoding();
}
return format;
}
/// <summary>
/// Parses the accepted charsets and matches them against the supported encodings for the given <paramref name="payloadKind"/>.
/// </summary>
/// <param name="acceptCharsetHeader">The Accept-Charset header of the request.</param>
/// <param name="payloadKind">The <see cref="ODataPayloadKind"/> for which to compute the encoding.</param>
/// <param name="mediaType">The media type used to compute the default encoding for the payload.</param>
/// <returns>The encoding to be used for the response.</returns>
private static Encoding GetEncoding(string acceptCharsetHeader, ODataPayloadKind payloadKind, MediaType mediaType)
{
if (payloadKind == ODataPayloadKind.BinaryValue)
{
return(null);
}
else
{
// TODO: we currently assume that the media type does not have a 'charset' parameter specified. This is true for
// the current uses of this method. Consider making this general purpose and also include the 'charset'
// parameter on the media type into the resolution process. (Currently the media type is only used to
// compute the default encoding).
return(HttpUtils.EncodingFromAcceptableCharsets(acceptCharsetHeader, mediaType, encodingUtf8NoPreamble, encodingUtf8NoPreamble));
}
}
