/// <summary>
/// Generates an OAuth Authorization header and adds it to the headers of the specified HttpWebRequest.
/// </summary>
/// <param name="webRequest">The HttpWebRequest object to sign.</param>
/// <param name="applicationCredentials">The OAuth application credentials.</param>
/// <param name="userCredentials">The OAuth user credentials.</param>
/// <param name="parameters">An IEnumerable collection of QueryParameters. For GET requests, this should include all parameters in the query string. For POST requests, this should include all parameters in the request body.</param>
public static void SignHttpWebRequest(HttpWebRequest webRequest, OAuthApplicationCredentials applicationCredentials, OAuthUserCredentials userCredentials, IEnumerable parameters = null)
{
// Get the OAuth parameters
ArrayList oauthParameters = GetOAuthParameters(applicationCredentials, userCredentials);
// Create a collection of all parameters (both OAuth authorization parameters and request parameters) for the OAuth signature
ArrayList allParameters = new ArrayList();
foreach (var p in oauthParameters)
{
allParameters.Add(p);
}
if (parameters != null)
{
foreach (var p in parameters)
{
allParameters.Add(p);
}
}
// Get the OAuth signature
// For GET requests, we need only the base URI (without the query string)
string uri = webRequest.RequestUri.AbsoluteUri;
int queryStringIndex = uri.IndexOf('?');
if (queryStringIndex >= 0)
{
uri = uri.Substring(0, queryStringIndex);
}
string oauthSignature = GenerateOAuthSignature(webRequest.Method, uri, allParameters, applicationCredentials, userCredentials);
// Add the signature to the OAuth parameters
oauthParameters.Add(new QueryParameter("oauth_signature", oauthSignature));
// Generate the Authorization header string
// Format: OAuth key1="value1", key2="value2", key3="value3"
string authorizationHeader = "OAuth ";
for (int i = 0; i < oauthParameters.Count; i++)
{
if (i > 0)
{
authorizationHeader += ", ";
}
QueryParameter parameter = (QueryParameter)oauthParameters[i];
authorizationHeader += Utility.UriEncode(parameter.Key) + "=\"" + Utility.UriEncode(parameter.Value) + "\"";
}
// Add the Authorization header to the request
webRequest.Headers.Add("Authorization", authorizationHeader);
}
private static ArrayList GetOAuthParameters(OAuthApplicationCredentials applicationCredentials, OAuthUserCredentials userCredentials)
{
ArrayList result = new ArrayList();
result.Add(new QueryParameter("oauth_consumer_key", applicationCredentials.ConsumerKey));
result.Add(new QueryParameter("oauth_nonce", Utility.GetRandomAlphanumericString(16)));
result.Add(new QueryParameter("oauth_signature_method", "HMAC-SHA1"));
result.Add(new QueryParameter("oauth_timestamp", DateTime.UtcNow.ToUnixTimestamp().ToString()));
result.Add(new QueryParameter("oauth_version", "1.0"));
result.Add(new QueryParameter("oauth_token", userCredentials.AccessToken));
return(result);
}
/// <summary>
/// Creates a TwitterClient with the specified application and user credentials.
/// </summary>
/// <param name="applicationCredentials">Application-specific credentials.</param>
/// <param name="userCredentials">User-specific credentials.</param>
public TwitterClient(OAuthApplicationCredentials applicationCredentials, OAuthUserCredentials userCredentials)
{
ApplicationCredentials = applicationCredentials;
UserCredentials = userCredentials;
}
private static string GenerateOAuthSignature(string method, string uri, IList parameters, OAuthApplicationCredentials applicationCredentials, OAuthUserCredentials userCredentials)
{
// Percent-encode each parameter
string[] encodedParameters = new string[parameters.Count];
for (int i = 0; i < parameters.Count; i++)
{
QueryParameter parameter = (QueryParameter)parameters[i];
encodedParameters[i] = Utility.UriEncode(parameter.Key) + "=" + Utility.UriEncode(parameter.Value);
}
// Sort the list of parameters alphabetically
Utility.SortList(encodedParameters);
// Join the parameters as a query string
string joinedParameters = Utility.StringJoin("&", encodedParameters);
// Generate the signature base
string signatureBase = method + '&' + Utility.UriEncode(uri) + '&' + Utility.UriEncode(joinedParameters);
// Generate the key
string key = applicationCredentials.ConsumerSecret + '&' + userCredentials.AccessTokenSecret;
// Compute the HMAC-SHA1 hash
byte[] keyBytes = Encoding.UTF8.GetBytes(key);
byte[] messageBytes = Encoding.UTF8.GetBytes(signatureBase);
byte[] hashBytes = SHA.ComputeHmacSHA1(keyBytes, messageBytes);
// The final signature should be a Base64-encoded version of the hash
return(Utility.ConvertToRFC4648Base64String(hashBytes));
}