/// <summary>
/// Retrieves an access token from ACS to call the source of the specified context token at the specified
/// targetHost. The targetHost must be registered for principal the that sent the context token.
/// </summary>
/// <param name="contextToken">Context token issued by the intended access token audience</param>
/// <param name="targetHost">Url authority of the target principal</param>
/// <returns>An access token with an audience matching the context token's source</returns>
public static OAuth2AccessTokenResponse GetAccessToken(SharePointContextToken contextToken, string targetHost)
{
string targetPrincipalName = contextToken.TargetPrincipalName;
// Extract the refreshToken from the context token
string refreshToken = contextToken.RefreshToken;
if (String.IsNullOrEmpty(refreshToken))
{
return null;
}
string realm = Realm ?? contextToken.Realm;
string resource = GetFormattedPrincipal(targetPrincipalName, targetHost, realm);
string clientId = GetFormattedPrincipal(ClientId, null, realm);
OAuth2AccessTokenRequest oauth2Request =
OAuth2MessageFactory.CreateAccessTokenRequestWithRefreshToken(
clientId,
ClientSecret,
refreshToken,
resource);
// Get token
OAuth2S2SClient client = new OAuth2S2SClient();
OAuth2AccessTokenResponse oauth2Response;
try
{
oauth2Response =
client.Issue(AcsMetadataParser.GetStsUrl(realm), oauth2Request) as OAuth2AccessTokenResponse;
}
catch (WebException wex)
{
using (StreamReader sr = new StreamReader(wex.Response.GetResponseStream()))
{
string responseText = sr.ReadToEnd();
throw new WebException(wex.Message + " - " + responseText, wex);
}
}
return oauth2Response;
}
protected void Page_Load(object sender, EventArgs e)
{
TokenHelper.TrustAllCertificates();
string contextTokenString = TokenHelper.GetContextTokenFromRequest(Request);
if (contextTokenString != null)
{
// Get context token
contextToken = TokenHelper.ReadAndValidateContextToken(contextTokenString, Request.Url.Authority);
// Get the host web's URL and the access token.
sharepointUrl = new Uri(Request.QueryString["SPHostUrl"]);
accessToken = TokenHelper.GetAccessToken(contextToken, sharepointUrl.Authority).AccessToken;
// Pass the access token to the button event handler.
Button1.CommandArgument = accessToken;
}
}