private static HashAlgorithm HashAlgorithmCreate(
FileDigestOptions options)
{
string algorithmName = options.DigestHashAlgorithm;
HashAlgorithm algorithm = null;
#if NETSTANDARD1_4 || NETSTANDARD2_0
switch (algorithmName)
{
case "SHA1":
case "SHA-1":
algorithm = SHA1.Create();
break;
case "SHA256":
case "SHA-256":
algorithm = SHA256.Create();
break;
case "SHA384":
case "SHA-384":
algorithm = SHA384.Create();
break;
case "SHA512":
case "SHA-512":
algorithm = SHA512.Create();
break;
}
#else
algorithm = HashAlgorithm.Create(algorithmName);
#endif
if (algorithm == null && options.DigestHashValue == null)
{
algorithm = DefaultHashAlgorithm();
options.DigestHashAlgorithm = algorithm.GetType().Name;
}
if (algorithm == null)
{
throw new InvalidOperationException($"No hash algorithm for '{algorithmName}'");
}
return(algorithm);
}
/// <summary>
/// Digest extension method on the <see cref="IFlurlClient"/>.
/// </summary>
/// <param name="content"><see cref="StreamContent"/></param>
/// <param name="fileStream"><see cref="Stream"/> of the filestream.
/// No digest is calculated if the stream is not <see cref="Stream.CanSeek"/>.</param>
/// <param name="options"><see cref="FileDigestOptions"/> digest options to use.</param>
/// <returns><see cref="IFlurlClient"/>.</returns>
public static StreamContent WithDigest(
this StreamContent content,
Stream fileStream,
FileDigestOptions options)
{
if (!options.UseFileDigesting || options.DigestHashAlgorithm == null)
{
return(content);
}
SetHashValue(fileStream, options);
string base64Digest = Convert.ToBase64String(options.DigestHashValue);
content.Headers.Add("Digest", $"{options.DigestHashAlgorithm}={base64Digest}");
return(content);
}
private static void SetHashValue(Stream fileStream, FileDigestOptions options)
{
if (options.DigestHashValue != null)
{
return;
}
if (!fileStream.CanSeek)
{
return;
}
long position = fileStream.Position;
using (var algo = HashAlgorithmCreate(options)) {
options.DigestHashValue = algo.ComputeHash(fileStream);
}
fileStream.Position = position;
}