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How do I get an OAuth 2.0 authentication token in C#

I have these settings:
Auth URL (which happens to be a
"https://login.microsoftonline.com/...") if that helps.
Access Token URL "https://service.endpoint.com/api/oauth2/token"
ClientId "abc"
Clientsecret "123"
I then need to make a get call using a bearer token in the header.
I can get this to work in Postman, but have hit a wall trying to work out how to implement it in C#. I've been using RestSharp (but open to others). It all seems so opaque, when I thought it'd be pretty straight forward: it's a console app, so I don't need bells and whistles.
Ultimately, I want my app to (programatically) get a token, then use that for my subsequent calls. I'd appreciate anyone pointing me to documentation or examples, that explains what I'm after clearly. Everything I've come across is partial or for services operating on a different flow.
Thanks.

In Postman, click Generate Code and then in Generate Code Snippets dialog you can select a different coding language, including C# (RestSharp).
Also, you should only need the access token URL. The form parameters are then:
grant_type=client_credentials
client_id=abc
client_secret=123
Code Snippet:
/* using RestSharp; // https://www.nuget.org/packages/RestSharp/ */
var client = new RestClient("https://service.endpoint.com/api/oauth2/token");
var request = new RestRequest(Method.POST);
request.AddHeader("cache-control", "no-cache");
request.AddHeader("content-type", "application/x-www-form-urlencoded");
request.AddParameter("application/x-www-form-urlencoded", "grant_type=client_credentials&client_id=abc&client_secret=123", ParameterType.RequestBody);
IRestResponse response = client.Execute(request);
From the response body you can then obtain your access token. For instance for a Bearer token type you can then add the following header to subsequent authenticated requests:
request.AddHeader("authorization", "Bearer <access_token>");

The Rest Client answer is perfect! (I upvoted it)
But, just in case you want to go "raw"
..........
I got this to work with HttpClient.
"abstractly" what you are doing is
creating a POST request.
with a body of payload "type" of 'x-www-form-urlencoded'. ( see FormUrlEncodedContent https://learn.microsoft.com/en-us/dotnet/api/system.net.http.formurlencodedcontent?view=net-5.0 and note the constructor : https://learn.microsoft.com/en-us/dotnet/api/system.net.http.formurlencodedcontent.-ctor?view=net-5.0)
and in the payload of 'type' : x-www-form-urlencoded, you are putting in certain values like the grant_type, client_id, client_secret etc.
Side note, try to get it working in PostMan, and then it is easier to "code it up" using the code below.
But here we go, code using HttpClient.
.......
/*
.nuget\packages\newtonsoft.json\12.0.1
.nuget\packages\system.net.http\4.3.4
*/
using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Threading.Tasks;
using System.Web;
private static async Task<Token> GetElibilityToken(HttpClient client)
{
string baseAddress = #"https://blah.blah.blah.com/oauth2/token";
string grant_type = "client_credentials";
string client_id = "myId";
string client_secret = "shhhhhhhhhhhhhhItsSecret";
var form = new Dictionary<string, string>
{
{"grant_type", grant_type},
{"client_id", client_id},
{"client_secret", client_secret},
};
HttpResponseMessage tokenResponse = await client.PostAsync(baseAddress, new FormUrlEncodedContent(form));
var jsonContent = await tokenResponse.Content.ReadAsStringAsync();
Token tok = JsonConvert.DeserializeObject<Token>(jsonContent);
return tok;
}
internal class Token
{
[JsonProperty("access_token")]
public string AccessToken { get; set; }
[JsonProperty("token_type")]
public string TokenType { get; set; }
[JsonProperty("expires_in")]
public int ExpiresIn { get; set; }
[JsonProperty("refresh_token")]
public string RefreshToken { get; set; }
}
Here is another working example (based off the answer above)......with a few more tweaks. Sometimes the token-service is finicky:
private static async Task<Token> GetATokenToTestMyRestApiUsingHttpClient(HttpClient client)
{
/* this code has lots of commented out stuff with different permutations of tweaking the request */
/* this is a version of asking for token using HttpClient. aka, an alternate to using default libraries instead of RestClient */
OAuthValues oav = GetOAuthValues(); /* object has has simple string properties for TokenUrl, GrantType, ClientId and ClientSecret */
var form = new Dictionary<string, string>
{
{ "grant_type", oav.GrantType },
{ "client_id", oav.ClientId },
{ "client_secret", oav.ClientSecret }
};
/* now tweak the http client */
client.DefaultRequestHeaders.Clear();
client.DefaultRequestHeaders.Add("cache-control", "no-cache");
/* try 1 */
////client.DefaultRequestHeaders.Add("content-type", "application/x-www-form-urlencoded");
/* try 2 */
////client.DefaultRequestHeaders .Accept .Add(new MediaTypeWithQualityHeaderValue("application/x-www-form-urlencoded"));//ACCEPT header
/* try 3 */
////does not compile */client.Content.Headers.ContentType = new MediaTypeHeaderValue("application/x-www-form-urlencoded");
////application/x-www-form-urlencoded
HttpRequestMessage req = new HttpRequestMessage(HttpMethod.Post, oav.TokenUrl);
/////req.RequestUri = new Uri(baseAddress);
req.Content = new FormUrlEncodedContent(form);
////string jsonPayload = "{\"grant_type\":\"" + oav.GrantType + "\",\"client_id\":\"" + oav.ClientId + "\",\"client_secret\":\"" + oav.ClientSecret + "\"}";
////req.Content = new StringContent(jsonPayload, Encoding.UTF8, "application/json");//CONTENT-TYPE header
req.Content.Headers.ContentType = new MediaTypeHeaderValue("application/x-www-form-urlencoded");
/* now make the request */
////HttpResponseMessage tokenResponse = await client.PostAsync(baseAddress, new FormUrlEncodedContent(form));
HttpResponseMessage tokenResponse = await client.SendAsync(req);
Console.WriteLine(string.Format("HttpResponseMessage.ReasonPhrase='{0}'", tokenResponse.ReasonPhrase));
if (!tokenResponse.IsSuccessStatusCode)
{
throw new HttpRequestException("Call to get Token with HttpClient failed.");
}
var jsonContent = await tokenResponse.Content.ReadAsStringAsync();
Token tok = JsonConvert.DeserializeObject<Token>(jsonContent);
return tok;
}
APPEND
Bonus Material!
If you ever get a
"The remote certificate is invalid according to the validation
procedure."
exception......you can wire in a handler to see what is going on (and massage if necessary)
using System;
using System.Collections.Generic;
using System.Text;
using Newtonsoft.Json;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Threading.Tasks;
using System.Web;
using System.Net;
namespace MyNamespace
{
public class MyTokenRetrieverWithExtraStuff
{
public static async Task<Token> GetElibilityToken()
{
using (HttpClientHandler httpClientHandler = new HttpClientHandler())
{
httpClientHandler.ServerCertificateCustomValidationCallback = CertificateValidationCallBack;
using (HttpClient client = new HttpClient(httpClientHandler))
{
return await GetElibilityToken(client);
}
}
}
private static async Task<Token> GetElibilityToken(HttpClient client)
{
// throws certificate error if your cert is wired to localhost //
//string baseAddress = #"https://127.0.0.1/someapp/oauth2/token";
//string baseAddress = #"https://localhost/someapp/oauth2/token";
string baseAddress = #"https://blah.blah.blah.com/oauth2/token";
string grant_type = "client_credentials";
string client_id = "myId";
string client_secret = "shhhhhhhhhhhhhhItsSecret";
var form = new Dictionary<string, string>
{
{"grant_type", grant_type},
{"client_id", client_id},
{"client_secret", client_secret},
};
HttpResponseMessage tokenResponse = await client.PostAsync(baseAddress, new FormUrlEncodedContent(form));
var jsonContent = await tokenResponse.Content.ReadAsStringAsync();
Token tok = JsonConvert.DeserializeObject<Token>(jsonContent);
return tok;
}
private static bool CertificateValidationCallBack(
object sender,
System.Security.Cryptography.X509Certificates.X509Certificate certificate,
System.Security.Cryptography.X509Certificates.X509Chain chain,
System.Net.Security.SslPolicyErrors sslPolicyErrors)
{
// If the certificate is a valid, signed certificate, return true.
if (sslPolicyErrors == System.Net.Security.SslPolicyErrors.None)
{
return true;
}
// If there are errors in the certificate chain, look at each error to determine the cause.
if ((sslPolicyErrors & System.Net.Security.SslPolicyErrors.RemoteCertificateChainErrors) != 0)
{
if (chain != null && chain.ChainStatus != null)
{
foreach (System.Security.Cryptography.X509Certificates.X509ChainStatus status in chain.ChainStatus)
{
if ((certificate.Subject == certificate.Issuer) &&
(status.Status == System.Security.Cryptography.X509Certificates.X509ChainStatusFlags.UntrustedRoot))
{
// Self-signed certificates with an untrusted root are valid.
continue;
}
else
{
if (status.Status != System.Security.Cryptography.X509Certificates.X509ChainStatusFlags.NoError)
{
// If there are any other errors in the certificate chain, the certificate is invalid,
// so the method returns false.
return false;
}
}
}
}
// When processing reaches this line, the only errors in the certificate chain are
// untrusted root errors for self-signed certificates. These certificates are valid
// for default Exchange server installations, so return true.
return true;
}
/* overcome localhost and 127.0.0.1 issue */
if ((sslPolicyErrors & System.Net.Security.SslPolicyErrors.RemoteCertificateNameMismatch) != 0)
{
if (certificate.Subject.Contains("localhost"))
{
HttpRequestMessage castSender = sender as HttpRequestMessage;
if (null != castSender)
{
if (castSender.RequestUri.Host.Contains("127.0.0.1"))
{
return true;
}
}
}
}
return false;
}
public class Token
{
[JsonProperty("access_token")]
public string AccessToken { get; set; }
[JsonProperty("token_type")]
public string TokenType { get; set; }
[JsonProperty("expires_in")]
public int ExpiresIn { get; set; }
[JsonProperty("refresh_token")]
public string RefreshToken { get; set; }
}
}
}
........................
I recently found (Jan/2020) an article about all this. I'll add a link here....sometimes having 2 different people show/explain it helps someone trying to learn it.
http://luisquintanilla.me/2017/12/25/client-credentials-authentication-csharp/

Here is a complete example. Right click on the solution to manage nuget packages and get Newtonsoft and RestSharp:
using Newtonsoft.Json.Linq;
using RestSharp;
using System;
namespace TestAPI
{
class Program
{
static void Main(string[] args)
{
string id = "xxx";
string secret = "xxx";
var client = new RestClient("https://xxx.xxx.com/services/api/oauth2/token");
var request = new RestRequest(Method.POST);
request.AddHeader("cache-control", "no-cache");
request.AddHeader("content-type", "application/x-www-form-urlencoded");
request.AddParameter("application/x-www-form-urlencoded", "grant_type=client_credentials&scope=all&client_id=" + id + "&client_secret=" + secret, ParameterType.RequestBody);
RestResponse response = client.Execute(request);
dynamic resp = JObject.Parse(response.Content);
string token = resp.access_token;
client = new RestClient("https://xxx.xxx.com/services/api/x/users/v1/employees");
request = new RestRequest(Method.GET);
request.AddHeader("authorization", "Bearer " + token);
request.AddHeader("cache-control", "no-cache");
response = client.Execute(request);
}
}
}

I used ADAL.NET/ Microsoft Identity Platform to achieve this. The advantage of using it was that we get a nice wrapper around the code to acquire AccessToken and we get additional features like Token Cache out-of-the-box. From the documentation:
Why use ADAL.NET ?
ADAL.NET V3 (Active Directory Authentication Library for .NET) enables developers of .NET applications to acquire tokens in order to call secured Web APIs. These Web APIs can be the Microsoft Graph, or 3rd party Web APIs.
Here is the code snippet:
// Import Nuget package: Microsoft.Identity.Client
public class AuthenticationService
{
private readonly List<string> _scopes;
private readonly IConfidentialClientApplication _app;
public AuthenticationService(AuthenticationConfiguration authentication)
{
_app = ConfidentialClientApplicationBuilder
.Create(authentication.ClientId)
.WithClientSecret(authentication.ClientSecret)
.WithAuthority(authentication.Authority)
.Build();
_scopes = new List<string> {$"{authentication.Audience}/.default"};
}
public async Task<string> GetAccessToken()
{
var authenticationResult = await _app.AcquireTokenForClient(_scopes)
.ExecuteAsync();
return authenticationResult.AccessToken;
}
}

You may use the following code to get the bearer token.
private string GetBearerToken()
{
var client = new RestClient("https://service.endpoint.com");
client.Authenticator = new HttpBasicAuthenticator("abc", "123");
var request = new RestRequest("api/oauth2/token", Method.POST);
request.AddHeader("content-type", "application/json");
request.AddParameter("application/json", "{ \"grant_type\":\"client_credentials\" }",
ParameterType.RequestBody);
var responseJson = _client.Execute(request).Content;
var token = JsonConvert.DeserializeObject<Dictionary<string, object>>(responseJson)["access_token"].ToString();
if(token.Length == 0)
{
throw new AuthenticationException("API authentication failed.");
}
return token;
}

This example get token thouth HttpWebRequest
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(pathapi);
request.Method = "POST";
string postData = "grant_type=password";
ASCIIEncoding encoding = new ASCIIEncoding();
byte[] byte1 = encoding.GetBytes(postData);
request.ContentType = "application/x-www-form-urlencoded";
request.ContentLength = byte1.Length;
Stream newStream = request.GetRequestStream();
newStream.Write(byte1, 0, byte1.Length);
HttpWebResponse response = request.GetResponse() as HttpWebResponse;
using (Stream responseStream = response.GetResponseStream())
{
StreamReader reader = new StreamReader(responseStream, Encoding.UTF8);
getreaderjson = reader.ReadToEnd();
}

My client is using grant_type=Authorization_code workflow.
I have below settings:
Auth URL (which happens to be a "https://login.microsoftonline.com/...") if that helps.
Access Token URL: "https://service.endpoint.com/api/oauth2/token"
ClientId: "xyz"
Clientsecret: "123dfsdf"
I then need to make a get call using a bearer token in the header. I tried all the above code sample, But whatever I will land on Microsoft - Sign in to you account" page as
"\r\n\r\n<!-- Copyright (C) Microsoft Corporation. All rights reserved. -->\r\n<!DOCTYPE html>\r\n<html dir=\"ltr\" class=\"\" lang=\"en\">\r\n<head>\r\n <title>Sign in to your account</title>\r\n "
I am able to execute on Postman and I observed there are 2 calls in console.
GET call for Authorization Code
POST call with above Authorization Code appended in the call to the the Access token.
I tried to execute the above GET call in a separately in POSTMAN, when I do that I will be prompted with microsoftonline login page, when I enter my credentials I will get salesforce error.
if anyone can provide sample code or examples of Authorization_code grand_type workflow That will be very great help...

Clearly:
Server side generating a token example
private string GenerateToken(string userName)
{
var someClaims = new Claim[]{
new Claim(JwtRegisteredClaimNames.UniqueName, userName),
new Claim(JwtRegisteredClaimNames.Email, GetEmail(userName)),
new Claim(JwtRegisteredClaimNames.NameId,Guid.NewGuid().ToString())
};
SecurityKey securityKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(_settings.Tokenizer.Key));
var token = new JwtSecurityToken(
issuer: _settings.Tokenizer.Issuer,
audience: _settings.Tokenizer.Audience,
claims: someClaims,
expires: DateTime.Now.AddHours(_settings.Tokenizer.ExpiryHours),
signingCredentials: new SigningCredentials(securityKey, SecurityAlgorithms.HmacSha256)
);
return new JwtSecurityTokenHandler().WriteToken(token);
}
(note: Tokenizer is my helper class that contains Issuer Audience etc..)
Definitely:
Client side getting a token for authentication
public async Task<string> GetToken()
{
string token = "";
var siteSettings = DependencyResolver.Current.GetService<SiteSettings>();
var client = new HttpClient();
client.BaseAddress = new Uri(siteSettings.PopularSearchRequest.StaticApiUrl);
client.DefaultRequestHeaders.Accept.Clear();
//client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
StatisticUserModel user = new StatisticUserModel()
{
Password = siteSettings.PopularSearchRequest.Password,
Username = siteSettings.PopularSearchRequest.Username
};
string jsonUser = JsonConvert.SerializeObject(user, Formatting.Indented);
var stringContent = new StringContent(jsonUser, Encoding.UTF8, "application/json");
var response = await client.PostAsync(siteSettings.PopularSearchRequest.StaticApiUrl + "/api/token/new", stringContent);
token = await response.Content.ReadAsStringAsync();
return token;
}
You can use this token for the authorization (that is in the subsequent requests)

https://github.com/IdentityModel/IdentityModel adds extensions to HttpClient to acquire tokens using different flows and the documentation is great too. It's very handy because you don't have to think how to implement it yourself. I'm not aware if any official MS implementation exists.

I tried this way to get OAuth 2.0 authentication token using c#
namespace ConsoleApp2
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine(GetToken());
Console.Read();
}
/// <summary>
/// Get access token from api
/// </summary>
/// <returns></returns>
private static string GetToken()
{
string wClientId = "#######";
string wClientSecretKey = "*********************";
string wAccessToken;
//--------------------------- Approch-1 to get token using HttpClient -------------------------------------------------------------------------------------
HttpResponseMessage responseMessage;
using (HttpClient client = new HttpClient())
{
HttpRequestMessage tokenRequest = new HttpRequestMessage(HttpMethod.Post, "https://localhost:1001/oauth/token");
HttpContent httpContent = new FormUrlEncodedContent(
new[]
{
new KeyValuePair<string, string>("grant_type", "client_credentials"),
});
tokenRequest.Content = httpContent;
tokenRequest.Headers.Add("Authorization", "Basic " + Convert.ToBase64String(Encoding.Default.GetBytes(wClientId + ":" + wClientSecretKey)));
responseMessage = client.SendAsync(tokenRequest).Result;
}
string ResponseJSON= responseMessage.Content.ReadAsStringAsync().Result;
//--------------------------- Approch-2 to get token using HttpWebRequest and deserialize json object into ResponseModel class -------------------------------------------------------------------------------------
byte[] byte1 = Encoding.ASCII.GetBytes("grant_type=client_credentials");
HttpWebRequest oRequest = WebRequest.Create("https://localhost:1001/oauth/token") as HttpWebRequest;
oRequest.Accept = "application/json";
oRequest.Method = "POST";
oRequest.ContentType = "application/x-www-form-urlencoded";
oRequest.ContentLength = byte1.Length;
oRequest.KeepAlive = false;
oRequest.Headers.Add("Authorization", "Basic " + Convert.ToBase64String(Encoding.Default.GetBytes(wClientId + ":" + wClientSecretKey)));
Stream newStream = oRequest.GetRequestStream();
newStream.Write(byte1, 0, byte1.Length);
WebResponse oResponse = oRequest.GetResponse();
using (var reader = new StreamReader(oResponse.GetResponseStream(), Encoding.UTF8))
{
var oJsonReponse = reader.ReadToEnd();
ResponseModel oModel = JsonConvert.DeserializeObject<ResponseModel>(oJsonReponse);
wAccessToken = oModel.access_token;
}
return wAccessToken;
}
}
//----------------------------------------------------------------------------------------------------------------------------------------------------
//---------------------------------- Response Class---------------------------------------------------------------------------------------
//----------------------------------------------------------------------------------------------------------------------------------------------------
/// <summary>
/// De-serialize Web response Object into model class to read
/// </summary>
public class ResponseModel
{
public string scope { get; set; }
public string token_type { get; set; }
public string expires_in { get; set; }
public string refresh_token { get; set; }
public string access_token { get; set; }
}
}

Twilio REST Api call bad request

I've implemented Twilio REST API with C# successfully earlier. However, all of a sudden the API calls that are made keep getting 400 - BAD REQUEST.
The response body doesn't contain any specific error either...
I'll say it again, it worked for a week or two and all of sudden it returns BAD REQUEST.
The code is exact the following below.
public async Task SendSmsAsync(string number, string message)
{
var accountSid = _configuration["Authentication:Twilio:AccountSID"];
var authToken = _configuration["Authentication:Twilio:AuthToken"];
var twilioNumber = _configuration["Authentication:Twilio:Number"];
var credentials = new NetworkCredential(accountSid, authToken);
var handler = new HttpClientHandler { Credentials = credentials };
using (var client = new HttpClient(handler))
{
var url = $"https://api.twilio.com/2010-04-01/Accounts/{ accountSid }/Messages";
var body = new List<KeyValuePair<string, string>>
{
new KeyValuePair<string, string>("To", number),
new KeyValuePair<string, string>("From", twilioNumber),
new KeyValuePair<string, string>("Body", message),
};
var content = new FormUrlEncodedContent(body);
content.Headers.ContentType.CharSet = "UTF-8";
var response = await client.PostAsync(url, content);
if (response.IsSuccessStatusCode)
{
//Uri success = response.Headers.Location;
}
}
}

Calll WebAPI in Webforms application from C#, authentication

I have a WebForms application which expose some WebAPI methods. The application uses standard Forms Authentication. I'm able to call methods from browser when I properly authenticated.
Now I want to call the API from c# application using HttpClient, but always receiving error 403 "Forbidden".
I can see that cookies container contains SessionId cookie.
The code:
var cookieContainer = new CookieContainer();
// authenticate
{
var webRequestHandler = new WebRequestHandler();
webRequestHandler.CookieContainer = cookieContainer;
webRequestHandler.UseCookies = true;
var client = new HttpClient(webRequestHandler);
client.BaseAddress = new Uri("https://localhost/<WEBFORMSAPP>/");
string unid = "<USERNAME$FIELD$NAME>";
string pwdid = "<PASSWORD$FIELD$NAME>";
HttpContent loginData = new FormUrlEncodedContent(
new List<KeyValuePair<string, string>>
{
new KeyValuePair<string, string>(unid, "<USERNAME>"),
new KeyValuePair<string, string>(pwdid, "<PASSWORD>"),
}
);
System.Net.ServicePointManager.ServerCertificateValidationCallback = delegate { return true; };
var postResult = client.PostAsync("<LOGINPAGE.aspx>", loginData);
postResult.Wait();
postResult.Result.EnsureSuccessStatusCode();
}
// call web api
{
var webRequestHandler = new WebRequestHandler();
webRequestHandler.CookieContainer = cookieContainer;
webRequestHandler.UseCookies = true;
var client = new HttpClient(webRequestHandler);
client.BaseAddress = new Uri("https://localhost/<WEBFORMSAPP>/");
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
System.Net.ServicePointManager.ServerCertificateValidationCallback = delegate { return true; };
var r = client.GetAsync("api/<SOME_METHOD>");
r.Wait();
r.Result.EnsureSuccessStatusCode(); // Fails with 403 error
}

To build the proper web request we need to provide server with the correct __VIEWSTATE value and the name of the button which cause the postback (in addition to the login/password pair).
To do this first we need to make a GET request to the login page and extract then __VIEWSTATE value.
I have used code from this blog post:
http://odetocode.com/articles/162.aspx
The code to create authorization cookies:
public CookieContainer CreateAuthorizationCookies(string login, string password)
{
var result = new CookieContainer();
System.Net.ServicePointManager.ServerCertificateValidationCallback = delegate { return true; };
var webRequestHandler = new WebRequestHandler();
webRequestHandler.CookieContainer = result;
webRequestHandler.UseCookies = true;
var client = new HttpClient(webRequestHandler);
client.BaseAddress = new Uri("https://*********/");
// get viewstate
string viewstate;
{
var r = client.GetStringAsync("***/LoginPage.aspx");
r.Wait();
// see http://odetocode.com/articles/162.aspx
viewstate = ExtractViewState(r.Result);
}
HttpContent loginData = new FormUrlEncodedContent(
new List<KeyValuePair<string, string>>
{
new KeyValuePair<string, string>("__VIEWSTATE", viewstate),
new KeyValuePair<string, string>("***$UserName", login),
new KeyValuePair<string, string>("***$Password", password),
new KeyValuePair<string, string>("***$LoginButton", "Log In"), // "value" of the HTML input element
}
);
var postResult = client.PostAsync("****/LoginPage.aspx", loginData);
postResult.Wait();
postResult.Result.EnsureSuccessStatusCode();
return result;
}
After that we can use created CookieContainer in the further requests.

Adding authorization to the headers

I have the following code:
...
AuthenticationHeaderValue authHeaders = new AuthenticationHeaderValue("OAuth2", Contract.AccessToken);
string result = await PostRequest.AuthenticatedGetData(fullUrl, null, authHeaders);
return result;
...
public static async Task<string> AuthenticatedGetData(string url, FormUrlEncodedContent data, AuthenticationHeaderValue authValue)
{
HttpClient client = new HttpClient();
client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue(authValue.Parameter);
HttpResponseMessage response = await client.PostAsync(new Uri(url), data);
response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/json");
response.EnsureSuccessStatusCode();
string responseBody = await response.Content.ReadAsStringAsync();
return responseBody;
}
The response = await part just continues an ongoing loop and nothing happens. Any ideas what I am doing wrong?
The question really is, how do I send the following header:
Authorization: OAuth2 ACCESS_TOKEN
to an external web api

I struggled with this. I kept getting an error saying "invalid format" because I have a custom implementation and the Authorization header is validated against certain standards. Adding the header this way however worked:
var http = new HttpClient();
http.DefaultRequestHeaders.TryAddWithoutValidation("Authorization", "key=XXX");

This line
client.DefaultRequestHeaders.Authorization =
new AuthenticationHeaderValue(authValue.Parameter);
Will produce this header value
Authorization: ACCESS_TOKEN
Where ACCESS_TOKEN is the value of authValue.Parameter. You want to assign the value you passed instead to get the required header
client.DefaultRequestHeaders.Authorization = authValue;
Will produce
Authorization: OAuth2 ACCESS_TOKEN

Had a similar issue when getting AuthenticationHeaderValue to work with my requests.
I was also using JWT JsonWebToken from GitHub.
I was able to get a token from the API, but was struggling to use it in other GETs and POSTs.
var jwt = JsonWebToken.Encode(token, APISECRET, JwtHashAlgorithm.HS256);
var tk = GetTokenFromApi(); // basically returns an encrypted string.
Manually using WebRequest:
Which worked fine.
request.ContentType = "application/json";
request.Method = "POST";
request.Headers.Set("Authorization", string.Format("Bearer {0}", tk));
When we switched to an HttpClient, and used the AuthenticationHeaderValue, could not figure out how to set it up correctly.After looking at the request string, i saw it added the "Authorization" for me. Played around with parameters, and this finally this worked.
var authenticationHeaderValue = new AuthenticationHeaderValue("Bearer", tk);

Maybe intresting for other people. Since I searched on this for a long time. But you have to save your cookies also and give it with your next request. First this is how i got my authentication code and hold my cookies in a static variable (in the first time i call this method I give an empty value to token).
public static CookieContainer CookieContainer;
public static async Task<string> Post<TRequest>( TRequest requestBody, string path, string token = "")
{
var baseUrl = new Uri($"urlFromApi");
CookieContainer = new CookieContainer();
using (var handler = new HttpClientHandler() { CookieContainer = CookieContainer })
using(var client = new HttpClient(handler){BaseAddress = baseUrl})
{
client.DefaultRequestHeaders.ConnectionClose = false;
if (!string.IsNullOrWhiteSpace(token))
{
client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", $"{token}");
}
ServicePointManager.FindServicePoint(client.BaseAddress).ConnectionLeaseTimeout = 60 * 1000; //1 minute using (var content = new ByteArrayContent(GetByteData(requestBody)))
using (var content = new ByteArrayContent(GetByteData(requestBody)))
{
content.Headers.ContentType = new MediaTypeHeaderValue("application/json");
var response = await client.PostAsync(String.Empty, content);
return await GetResponseContent(response);
}
}
}
After this if I do any request to the api I include the cookies (token is what you get from the first response as a result)
public static async Task Get(string path, string token = "")
{
var baseUrl = $"https://innoviris-ai.collibra.com/rest/2.0{path}";
using (var handler = new HttpClientHandler() { CookieContainer = CookieContainer })
using (var client = new HttpClient(handler) {BaseAddress = new Uri(baseUrl)})
{
client.DefaultRequestHeaders.ConnectionClose = false;
if (!string.IsNullOrWhiteSpace(token))
{
client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", $"{token}");
}
ServicePointManager.FindServicePoint(client.BaseAddress).ConnectionLeaseTimeout = 60 * 1000; //1 minute
var response = await client.GetAsync(String.Empty);
return await GetResponseContent(response);
}
}

In your code you are doing this:
client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", $"{token}");
I think the following should work the same manner without using string interpolation:
client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
This is because the string interpolation is just generating a string with the token in it!

Paypal REST api call works from cURL but not from C# code

I'm trying to call Paypal api from my code. I set up the sandbox account and it works when I use curl but my code isn't working the same way, returning 401 Unauthorized instead.
Here's the curl command as documented by Paypal
curl https://api.sandbox.paypal.com/v1/oauth2/token -H "Accept: application/json" -H "Accept-Language: en_US" -u "A****:E****" -d "grant_type=client_credentials"
UPDATE: Apparently the .Credentials doesn't do the trick, instead setting Authorization header manually works (see code)
Here's the code (trimmed to its essence):
HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create("https://api.sandbox.paypal.com/v1/oauth2/token");
request.Method = "POST";
request.Accept = "application/json";
request.Headers.Add("Accept-Language:en_US")
// this doesn't work:
**request.Credentials = new NetworkCredential("A****", "E****");**
// DO THIS INSTEAD
**string authInfo = Convert.ToBase64String(System.Text.Encoding.Default.GetBytes("A****:E****"));**
**request.Headers["Authorization"] = "Basic " + authInfo;**
using (StreamWriter swt = new StreamWriter(request.GetRequestStream()))
{
swt.Write("grant_type=client_credentials");
}
request.BeginGetResponse((r) =>
{
try
{
HttpWebResponse response = request.EndGetResponse(r) as HttpWebResponse; // Exception here
....
} catch (Exception x) { .... } // log the exception - 401 Unauthorized
}, null);
This is the request from code captured by Fiddler (raw), there are no authorization parameters for some reason:
POST https://api.sandbox.paypal.com/v1/oauth2/token HTTP/1.1
Accept: application/json
Accept-Language: en_US
Host: api.sandbox.paypal.com
Content-Length: 29
Expect: 100-continue
Connection: Keep-Alive
grant_type=client_credentials

Hoping the following code help to anyone who is still looking for a good piece of cake to get connected to PayPal.
As many people, I've been investing a lot of time trying to get my PayPal token access without success, until I found the following:
public class PayPalClient
{
public async Task RequestPayPalToken()
{
// Discussion about SSL secure channel
// http://stackoverflow.com/questions/32994464/could-not-create-ssl-tls-secure-channel-despite-setting-servercertificatevalida
ServicePointManager.ServerCertificateValidationCallback += (sender, cert, chain, sslPolicyErrors) => true;
ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3 | SecurityProtocolType.Tls | SecurityProtocolType.Tls11 | SecurityProtocolType.Tls12;
try
{
// ClientId of your Paypal app API
string APIClientId = "**_[your_API_Client_Id]_**";
// secret key of you Paypal app API
string APISecret = "**_[your_API_secret]_**";
using (var client = new System.Net.Http.HttpClient())
{
var byteArray = Encoding.UTF8.GetBytes(APIClientId + ":" + APISecret);
client.DefaultRequestHeaders.Authorization = new System.Net.Http.Headers.AuthenticationHeaderValue("Basic", Convert.ToBase64String(byteArray));
var url = new Uri("https://api.sandbox.paypal.com/v1/oauth2/token", UriKind.Absolute);
client.DefaultRequestHeaders.IfModifiedSince = DateTime.UtcNow;
var requestParams = new List<KeyValuePair<string, string>>
{
new KeyValuePair<string, string>("grant_type", "client_credentials")
};
var content = new FormUrlEncodedContent(requestParams);
var webresponse = await client.PostAsync(url, content);
var jsonString = await webresponse.Content.ReadAsStringAsync();
// response will deserialized using Jsonconver
var payPalTokenModel = JsonConvert.DeserializeObject<PayPalTokenModel>(jsonString);
}
}
catch (System.Exception ex)
{
//TODO: Log connection error
}
}
}
public class PayPalTokenModel
{
public string scope { get; set; }
public string nonce { get; set; }
public string access_token { get; set; }
public string token_type { get; set; }
public string app_id { get; set; }
public int expires_in { get; set; }
}
This code works pretty well for me, hoping for you too. The credits belong to Patel Harshal who posted his solution here.

This Works using HttpClient...
'RequestT' is a generic for the PayPal request arguments, however it is not used. The 'ResponseT' is used and it is the response from PayPal according to their documentation.
'PayPalConfig' class reads the clientid and secret from the web.config file using ConfigurationManager.
The thing to remember is to set the Authorization header to "Basic" NOT "Bearer" and if and to properly construct the 'StringContent' object with right media type (x-www-form-urlencoded).
//gets PayPal accessToken
public async Task<ResponseT> InvokePostAsync<RequestT, ResponseT>(RequestT request, string actionUrl)
{
ResponseT result;
// 'HTTP Basic Auth Post' <http://stackoverflow.com/questions/21066622/how-to-send-a-http-basic-auth-post>
string clientId = PayPalConfig.clientId;
string secret = PayPalConfig.clientSecret;
string oAuthCredentials = Convert.ToBase64String(Encoding.Default.GetBytes(clientId + ":" + secret));
//base uri to PayPAl 'live' or 'stage' based on 'productionMode'
string uriString = PayPalConfig.endpoint(PayPalConfig.productionMode) + actionUrl;
HttpClient client = new HttpClient();
//construct request message
var h_request = new HttpRequestMessage(HttpMethod.Post, uriString);
h_request.Headers.Authorization = new AuthenticationHeaderValue("Basic", oAuthCredentials);
h_request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
h_request.Headers.AcceptLanguage.Add(new StringWithQualityHeaderValue("en_US"));
h_request.Content = new StringContent("grant_type=client_credentials", UTF8Encoding.UTF8, "application/x-www-form-urlencoded");
try
{
HttpResponseMessage response = await client.SendAsync(h_request);
//if call failed ErrorResponse created...simple class with response properties
if (!response.IsSuccessStatusCode)
{
var error = await response.Content.ReadAsStringAsync();
ErrorResponse errResp = JsonConvert.DeserializeObject<ErrorResponse>(error);
throw new PayPalException { error_name = errResp.name, details = errResp.details, message = errResp.message };
}
var success = await response.Content.ReadAsStringAsync();
result = JsonConvert.DeserializeObject<ResponseT>(success);
}
catch (Exception)
{
throw new HttpRequestException("Request to PayPal Service failed.");
}
return result;
}
IMPORTANT: use Task.WhenAll() to ensure you have a result.
// gets access token with HttpClient call..and ensures there is a Result before continuing
// so you don't try to pass an empty or failed token.
public async Task<TokenResponse> AuthorizeAsync(TokenRequest req)
{
TokenResponse response;
try
{
var task = new PayPalHttpClient().InvokePostAsync<TokenRequest, TokenResponse>(req, req.actionUrl);
await Task.WhenAll(task);
response = task.Result;
}
catch (PayPalException ex)
{
response = new TokenResponse { access_token = "error", Error = ex };
}
return response;
}

Paypal has deprecated TLS 1.1, and only accepts 1.2 now. Unfortunately .NET (prior to version 4.7) uses 1.1 by default, unless you configure it otherwise.
You can turn on TLS 1.2 with this line. I recomend placing it Application_Start or global.asax.
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;

I too suffered from a lack of example code and various issues with response errors and codes.
I am a big fan of RestClient as it helps a lot with integrations and the growing number of RESTful API calls.
I hope this small snippet of code using RestSharp helps someone: -
if (ServicePointManager.SecurityProtocol != SecurityProtocolType.Tls12) ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12; // forced to modern day SSL protocols
var client = new RestClient(payPalUrl) { Encoding = Encoding.UTF8 };
var authRequest = new RestRequest("oauth2/token", Method.POST) {RequestFormat = DataFormat.Json};
client.Authenticator = new HttpBasicAuthenticator(clientId, secret);
authRequest.AddParameter("grant_type","client_credentials");
var authResponse = client.Execute(authRequest);
// You can now deserialise the response to get the token as per the answer from #ryuzaki
var payPalTokenModel = JsonConvert.DeserializeObject<PayPalTokenModel>(authResponse.Content);