/// <summary>
/// Validates the specified request.
/// </summary>
/// <param name="request">The <see cref="HttpRequestMessage"/> to validate</param>
/// <param name="resolver">An account name to shared secret resolver.</param>
/// <param name="maxAge">The maximum age of a message that will be accepted</param>
/// <returns>A ClaimsPrincipal for the the identity which owns the message.</returns>
public static ClaimsPrincipal Validate(HttpRequestMessage request, Func <string, byte[]> resolver, TimeSpan maxAge)
{
AuthenticationHeaderValue authenticationHeader = null;
if (request.Headers != null)
{
authenticationHeader = request.Headers.Authorization;
}
string accountName;
byte[] sentHmac;
if (request.Headers != null && DateTime.Now - request.Headers.Date > maxAge)
{
throw new ForbiddenException("Request expired.");
}
if (authenticationHeader == null ||
string.IsNullOrWhiteSpace(authenticationHeader.Parameter) ||
authenticationHeader.Scheme != SharedKeyAuthentication.Scheme ||
!SharedKeyAuthentication.TryParse(authenticationHeader.Parameter, out accountName, out sentHmac))
{
return(AnonymousPrincipal);
}
byte[] sharedKey = resolver(accountName);
if (sharedKey == null || sharedKey.Length == 0)
{
// Account not found
throw new UnauthorizedException();
}
if (request.Headers.TransferEncodingChunked == null || !(bool)request.Headers.TransferEncodingChunked)
{
if (request.Content.Headers.ContentLength != null && (long)request.Content.Headers.ContentLength > 0)
{
var sentHash = request.Content.Headers.ContentMD5;
if (sentHash == null)
{
throw new ForbiddenException(
"Content-MD5 header must be specified when a request body is included.");
}
if (!CompareHash(sentHash, SignatureValidator.CalculateBodyMd5(request).Result))
{
throw new PreconditionFailedException("Content-MD5 does not match the request body.");
}
}
}
// Now check the actual auth signature.
byte[] calculatedHmac = SharedKeySignature.Calculate(request, accountName, sharedKey);
if (!CompareHash(sentHmac, calculatedHmac))
{
throw new ForbiddenException("Token validation failed.");
}
var claims = new List <Claim> {
new Claim(ClaimTypes.Name, accountName)
};
var claimsIdentity = new ClaimsIdentity(claims, SharedKeyAuthentication.Scheme);
var claimsPrincipal = new ClaimsPrincipal(claimsIdentity);
return(claimsPrincipal);
}