private SecureString GetAppSecret(string appId)
{
SecureString secret = appSecretProvider.GetSecret(appId);
if (secret == null || secret.Length == 0)
{
throw new HmacAuthenticationException($"App secret key not found: '{appId}'");
}
return(secret);
}
protected override async Task <HttpResponseMessage> SendAsync(
HttpRequestMessage request,
CancellationToken cancellationToken)
{
var req = request;
var h = req.Headers;
if (mixedAuthMode && h.Authorization?.Scheme != Schemas.HMAC)
{
return(await base.SendAsync(request, cancellationToken));
}
var appId = h.Contains(Headers.XAppId)
? h.GetValues(Headers.XAppId).FirstOrDefault()
: null;
var authValue = h.Authorization?.Parameter;
var date = h.Date ?? DateTimeOffset.MinValue;
if (appId != null &&
authValue != null &&
time.UtcNow - date <= tolerance)
{
var builder = new CannonicalRepresentationBuilder();
var content = builder.BuildRepresentation(
h.GetValues(Headers.XNonce).FirstOrDefault(),
appId,
req.Method.Method,
req.Content.Headers.ContentType?.ToString(),
string.Join(", ", req.Headers.Accept),
req.Content.Headers.ContentMD5,
date,
req.RequestUri);
SecureString secret;
if (content != null && (secret = appSecretRepository.GetSecret(appId)) != null)
{
var signature = signingAlgorithm.Sign(secret, content);
if (authValue == signature)
{
return(await base.SendAsync(request, cancellationToken));
}
}
}
return(new HttpResponseMessage(HttpStatusCode.Unauthorized)
{
Headers =
{
{ Headers.WWWAuthenticate, Schemas.HMAC }
}
});
}
public override async Task Invoke(IOwinContext context)
{
var req = context.Request;
var res = context.Response;
var h = req.Headers;
var appId = h.Get(Headers.XAppId);
var auth = h.Get(Headers.Authorization)?.Split(' ');
var authSchema = auth?.Length == 2 ? auth[0] : null;
var authValue = auth?.Length == 2 ? auth[1] : null;
DateTimeOffset date =
DateTimeOffset.TryParse(h.Get(Headers.Date), out date)
? date
: DateTimeOffset.MinValue;
if (appId != null &&
authSchema == Schemas.HMAC &&
authValue != null &&
time.UtcNow - date <= tolerance)
{
var builder = new CannonicalRepresentationBuilder();
var content = builder.BuildRepresentation(
h.Get(Headers.XNonce),
appId,
req.Method,
req.ContentType,
req.Accept,
Convert.FromBase64String(h.Get(Headers.ContentMD5)),
date,
req.Uri);
SecureString secret;
if (content != null && (secret = appSecretRepository.GetSecret(appId)) != null)
{
var signature = signingAlgorithm.Sign(secret, content);
if (authValue == signature)
{
await Next.Invoke(context);
return;
}
}
}
res.StatusCode = 401;
res.Headers.Append(Headers.WWWAuthenticate, Schemas.HMAC);
}
internal static bool Validate(IOwinRequest req, ISigningAlgorithm algorithm, IAppSecretRepository appSecretRepository, ITime time, TimeSpan tolerance)
{
var h = req.Headers;
var appId = GetAppId(req);
var nonce = GetNonce(req);
var auth = h.Get(Headers.Authorization)?.Split(' ');
var authSchema = auth?.Length == 2 ? auth[0] : null;
var authValue = auth?.Length == 2 ? auth[1] : null;
DateTimeOffset date =
DateTimeOffset.TryParse(h.Get(Headers.Date), out date)
? date
: DateTimeOffset.MinValue;
if (appId != null &&
authSchema == Schemas.HMAC &&
authValue != null &&
time.UtcNow - date <= tolerance)
{
var contentMd5 = h.Get(Headers.ContentMD5);
var builder = new CannonicalRepresentationBuilder();
var content = builder.BuildRepresentation(
nonce,
appId,
req.Method,
req.ContentType,
req.Accept,
contentMd5 == null ? null : Convert.FromBase64String(contentMd5),
date,
req.Uri);
SecureString secret;
if (content != null && (secret = appSecretRepository.GetSecret(appId)) != null)
{
var signature = algorithm.Sign(secret, content);
if (authValue == signature)
{
return(true);
}
}
}
return(false);
}
