/// <summary>
/// Checks if a request is valid based on what the client passed
/// </summary>
/// <param name="content">The content that the client passed</param>
/// <param name="resource">The resource that the client requested (URI ENCODED)</param>
/// <param name="resourceRequestMethod">The method that the client used to request the resource (ALL UPPER)</param>
/// <param name="appId">The appId the client is claiming to be</param>
/// <param name="incomingBase64Signature">The base64 signature the client passed</param>
/// <param name="nonce">The nonce the client provided to identify the request</param>
/// <param name="requestTimeStamp">The timestamp the client provided to identify the request</param>
/// <returns>(Is the request valid, description of the result)</returns>
protected virtual Tuple <bool, HmacIsValidRequestResult> IsValidRequest(Stream content, string resource, string resourceRequestMethod, string appId,
string incomingBase64Signature, string nonce, string requestTimeStamp)
{
if (string.IsNullOrWhiteSpace(resource))
{
LoggingService.LogMessage("HMAC Auth Resource Not Valid",
"No valid request requested resource", LogLevel.Debug);
return(new Tuple <bool, HmacIsValidRequestResult>(false, HmacIsValidRequestResult.NoValidResouce));
}
string requestContentBase64String = "";
ApiKeyService.TryGetValue(appId, out string sharedKey);
if (string.IsNullOrWhiteSpace(sharedKey))
{
LoggingService.LogMessage("Api Auth Request Not Valid",
"Unable to find appId", LogLevel.Debug);
return(new Tuple <bool, HmacIsValidRequestResult>(false, HmacIsValidRequestResult.UnableToFindAppId));
}
if (IsReplayRequest(nonce, requestTimeStamp))
{
LoggingService.LogMessage("Api Auth Request Not Valid",
"Looked like a replay request.\r\nNonce - " + nonce + "\r\nRequest Timestamp - " + requestTimeStamp
+ "\r\nOur Timestamp" + (DateTime.UtcNow - Constants.DateTime.UnixEpoch).TotalSeconds, LogLevel.Debug);
return(new Tuple <bool, HmacIsValidRequestResult>(false,
HmacIsValidRequestResult.ReplayRequest));
}
// we need a content stream (we need to make sure we pass this back)
Tuple <Stream, byte[], string> hashAndContent = ComputeHash(content);
if (hashAndContent.Item2 != null)
{
requestContentBase64String = Convert.ToBase64String(hashAndContent.Item2);
}
string encodedResource =
System.Web.HttpUtility.UrlEncode(resource.ToLower());
string data =
$"{appId}{resourceRequestMethod}{encodedResource}{requestTimeStamp}{nonce}{requestContentBase64String}";
byte[] secretKeyBytes = Convert.FromBase64String(sharedKey);
byte[] signature = data.GetBytes();
using (HMACSHA256 hmac = new HMACSHA256(secretKeyBytes))
{
byte[] signatureBytes = hmac.ComputeHash(signature);
string signatureString = Convert.ToBase64String(signatureBytes);
bool matched = incomingBase64Signature.Equals(signatureString,
StringComparison.Ordinal);
if (!matched)
{
LoggingService.LogMessage("Api Auth Request Not Valid",
"Signatures didn't match.\r\nRequest Signature - " + incomingBase64Signature
+ ".\r\nInternal Signature - " + signatureString + ".\r\nInternal signature data - " + data
+ "\r\nRaw Content - " + hashAndContent.Item2,
LogLevel.Debug);
}
return(new Tuple <bool, HmacIsValidRequestResult>(matched, matched
? HmacIsValidRequestResult.NoError
: HmacIsValidRequestResult.SignaturesMismatch));
}
}
