/// <summary>
/// Create an HttpWebRequest for a content-item service message. This is experimental.
/// </summary>
/// <param name="url">The content-item service URL.</param>
/// <param name="consumerKey">The OAuth consumer key to use to sign the request.</param>
/// <param name="consumerSecret">The OAuth consumer secret to use to sign the request.</param>
/// <param name="response">The ContentItemsServiceResponse to POST.</param>
/// <returns>The HttpWebRequest that will POST the message.</returns>
private static HttpWebRequest CreateContentItemsRequest(
string url, string consumerKey, string consumerSecret,
ContentItemsServiceResponse response)
{
var webRequest = (HttpWebRequest)WebRequest.Create(url);
webRequest.Method = "POST";
webRequest.ContentType = LtiConstants.ContentItemsMediaType;
var parameters = new NameValueCollection();
parameters.AddParameter(OAuthConstants.ConsumerKeyParameter, consumerKey);
parameters.AddParameter(OAuthConstants.NonceParameter, Guid.NewGuid().ToString());
parameters.AddParameter(OAuthConstants.SignatureMethodParameter, OAuthConstants.SignatureMethodHmacSha1);
parameters.AddParameter(OAuthConstants.VersionParameter, OAuthConstants.Version10);
// Calculate the timestamp
var ts = DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0, 0);
var timestamp = Convert.ToInt64(ts.TotalSeconds);
parameters.AddParameter(OAuthConstants.TimestampParameter, timestamp);
// Calculate the body hash
using (var sha1 = new SHA1CryptoServiceProvider())
{
var json = JsonConvert.SerializeObject(response, new JsonSerializerSettings {
NullValueHandling = NullValueHandling.Ignore
});
var content = Encoding.Unicode.GetBytes(json);
webRequest.ContentLength = content.Length;
using (var stream = webRequest.GetRequestStream())
{
stream.Write(content, 0, content.Length);
}
var hash = sha1.ComputeHash(content);
var hash64 = Convert.ToBase64String(hash);
parameters.AddParameter(OAuthConstants.BodyHashParameter, hash64);
}
// Calculate the signature
var signature = OAuthUtility.GenerateSignature(webRequest.Method, webRequest.RequestUri, parameters,
consumerSecret);
parameters.AddParameter(OAuthConstants.SignatureParameter, signature);
// Build the Authorization header
var authorization = new StringBuilder(OAuthConstants.AuthScheme).Append(" ");
foreach (var key in parameters.AllKeys)
{
authorization.AppendFormat("{0}=\"{1}\",", key, HttpUtility.UrlEncode(parameters[key]));
}
webRequest.Headers["Authorization"] = authorization.ToString(0, authorization.Length - 1);
return(webRequest);
}
/// <summary>
/// Send content-item response to Tool Consumer content-item service. This is experimental.
/// </summary>
/// <param name="url">The content-item service URL (from content-item message).</param>
/// <param name="consumerKey">The OAuth consumer key to use to sign the request.</param>
/// <param name="consumerSecret">The OAuth consumer secret to use to sign the request.</param>
/// <param name="contentItems">The ContentItemPlacementResponse to POST.</param>
/// <param name="data">The data received in the original content-item message.</param>
/// <returns>Return True if the POST request is successful.</returns>
public static bool PostContentItems(
string url, string consumerKey, string consumerSecret,
ContentItemPlacementResponse contentItems, string data)
{
var serviceResponse = new ContentItemsServiceResponse
{
ContentItems = contentItems,
Data = data
};
try
{
var webRequest = CreateContentItemsRequest(url, consumerKey, consumerSecret, serviceResponse);
using (var webResponse = webRequest.GetResponse() as HttpWebResponse)
{
return(webResponse != null && webResponse.StatusCode == HttpStatusCode.OK);
}
}
catch (Exception)
{
return(false);
}
}