public MetadataParserResult ParseSingleItem(string metadataItem, ICollection <string> existingKeys)
{
var pairParts = metadataItem.TrimEnd(' ').Split(new[] { ' ' });
if (pairParts.Length < 1 || pairParts.Length > 2)
{
return(MetadataParserResult.FromError($"Header {HeaderConstants.UploadMetadata}: The Upload-Metadata request and response header MUST consist of one or more comma - separated key - value pairs. The key and value MUST be separated by a space.The key MUST NOT contain spaces and commas and MUST NOT be empty. The key SHOULD be ASCII encoded and the value MUST be Base64 encoded. All keys MUST be unique. The value MAY be empty. In these cases, the space, which would normally separate the key and the value, MAY be left out."));
}
var key = pairParts[0];
if (string.IsNullOrEmpty(key))
{
return(MetadataParserResult.FromError($"Header {HeaderConstants.UploadMetadata}: Key must not be empty"));
}
if (existingKeys.Contains(key))
{
return(MetadataParserResult.FromError($"Header {HeaderConstants.UploadMetadata}: Duplicate keys are not allowed"));
}
try
{
return(MetadataParserResult.FromResult(key, GetMetadataValue(pairParts)));
}
catch (FormatException)
{
return(MetadataParserResult.FromError($"Header {HeaderConstants.UploadMetadata}: Value for {key} is not properly encoded using base64"));
}
}
/// <summary>
/// Parse and validate the provided <paramref name="uploadMetadataHeaderValue"/> into a class structure.
/// </summary>
/// <param name="strategy">The strategy to use when parsing. <c>MetadataParsingStrategy.Original</c> requires that the metadata provided is composed of key value pairs while <c>MetadataParsingStrategy.AllowEmptyValues</c> allows the use of metadata keys without values.</param>
/// <param name="uploadMetadataHeaderValue"></param>
/// <returns>A <see cref="MetadataParserResult"/> containing the result of the operation.</returns>
public static MetadataParserResult ParseAndValidate(MetadataParsingStrategy strategy, string uploadMetadataHeaderValue)
{
/*
* The Upload-Metadata request and response header MUST consist of one or more comma-separated key-value pairs.
* The key and value MUST be separated by a space.
* The key MUST NOT contain spaces and commas and MUST NOT be empty.
* The key SHOULD be ASCII encoded and the value MUST be Base64 encoded.
* All keys MUST be unique.
* The value MAY be empty.
* In these cases, the space, which would normally separate the key and the value, MAY be left out.
*
* NOTE:
* Empty values were not allowed from the beginning and was added later.
* This is why we use a MetadataParserStrategy.
* MetadataParserStrategy.AllowEmptyValues will also allow an present but empty Upload-Metadata header
* to help with compatibility with clients that are less than ideal.
* */
var parser = GetParser(strategy);
if (string.IsNullOrWhiteSpace(uploadMetadataHeaderValue))
{
return(parser.GetResultForEmptyHeader());
}
var splitMetadataHeader = uploadMetadataHeaderValue.Split(',');
var parsedMetadata = new Dictionary <string, Metadata>(splitMetadataHeader.Length);
foreach (var pair in splitMetadataHeader)
{
var singleItemParseResult = parser.ParseSingleItem(pair, parsedMetadata.Keys);
if (singleItemParseResult.Success)
{
var parsedKeyAndValue = singleItemParseResult.Metadata.First();
parsedMetadata.Add(parsedKeyAndValue.Key, parsedKeyAndValue.Value);
}
else
{
return(singleItemParseResult);
}
}
return(MetadataParserResult.FromResult(parsedMetadata));
}
public MetadataParserResult GetResultForEmptyHeader()
{
return(MetadataParserResult.FromResult(new Dictionary <string, Metadata>()));
}
public MetadataParserResult GetResultForEmptyHeader()
{
return(MetadataParserResult.FromError($"Header {HeaderConstants.UploadMetadata} must consist of one or more comma-separated key-value pairs"));
}
