public static async Task <string> GetAccessToken(
string accessTokenUri,
string clientId,
string clientSecret,
int timeout = DEFAULT_GETACCESSTOKEN_TIMEOUT,
bool validateCertificates = DEFAULT_VALIDATE_CERTIFICATES,
ILogger logger = null)
{
if (string.IsNullOrEmpty(accessTokenUri))
{
throw new ArgumentException(nameof(accessTokenUri));
}
if (string.IsNullOrEmpty(clientId))
{
throw new ArgumentException(nameof(accessTokenUri));
}
if (string.IsNullOrEmpty(clientSecret))
{
throw new ArgumentException(nameof(accessTokenUri));
}
var request = new HttpRequestMessage(HttpMethod.Post, accessTokenUri);
HttpClient client = GetHttpClient(validateCertificates, timeout);
// If certificate validation is disabled, inject a callback to handle properly
HttpClientHelper.ConfigureCertificateValidation(validateCertificates, out SecurityProtocolType prevProtocols, out RemoteCertificateValidationCallback prevValidator);
AuthenticationHeaderValue auth = new AuthenticationHeaderValue("Basic", GetEncodedUserPassword(clientId, clientSecret));
request.Headers.Authorization = auth;
request.Content = new FormUrlEncodedContent(new Dictionary <string, string>
{
{ "grant_type", "client_credentials" }
});
try
{
using (client)
{
using (HttpResponseMessage response = await client.SendAsync(request).ConfigureAwait(false))
{
if (response.StatusCode != HttpStatusCode.OK)
{
logger?.LogInformation(
"GetAccessToken returned status: {0} while obtaining access token from: {1}",
response.StatusCode,
accessTokenUri);
return(null);
}
var payload = JObject.Parse(await response.Content.ReadAsStringAsync());
var token = payload.Value <string>("access_token");
return(token);
}
}
}
catch (Exception e)
{
logger?.LogError("GetAccessToken exception: {0} ,obtaining access token from: {1}", e, WebUtility.UrlEncode(accessTokenUri));
}
finally
{
HttpClientHelper.RestoreCertificateValidation(validateCertificates, prevProtocols, prevValidator);
}
return(null);
}