Multi tool use

Getting Bad Request when requesting JWT in web API from Xamarin Forms

So I made a web API that authenticates with JSON Web Tokens, however, I haven't been able to authenticate using the HttpClient from my xamarin forms application. The odd thing is that I can connect without any problem on a console application that I made for testing, and both the console application and the xamarin forms app use almost exactly the same code.

The code in the console app is like this:

public static async Task<AutenticacionModel> PostCredentialsAsync(string UserName, string Password)
{
HttpClient cliente = new HttpClient();
cliente.BaseAddress = new Uri("http://172.25.1.53:9891");
HttpResponseMessage response = new HttpResponseMessage();
string _result = String.Empty;
try
{
string Path = cliente.BaseAddress + "oauth/secreto";
HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, Path);
string autenticacion = "username=" + UserName + "&password=" + Password + "&grant_type=password";
request.Content = new StringContent(autenticacion, Encoding.UTF8, "application/x-www-form-urlencoded");
response = await cliente.SendAsync(request);
response.EnsureSuccessStatusCode();
_result = await response.Content.ReadAsStringAsync();
}
catch (Exception ex)
{
// something to do
}
return response.Content != null ? JsonConvert.DeserializeObject<AutenticacionModel>(_result) : new AutenticacionModel();
}


And the code in the Xamarin Forms:

public async Task<AutenticacionDTO> GetUsuario(string email, string clave)
{
string JSONAutenticacion;
HttpResponseMessage response = new HttpResponseMessage();

try
{
var client = new HttpClient();

client.BaseAddress = new Uri(GlobalSetting.UrlWebApi);
string Path = client.BaseAddress + "oauth/secreto";
HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, Path);
string autenticacion = "username=" + email + "&password=" + clave + "&grant_type=password";
request.Content = new StringContent(autenticacion, Encoding.UTF8, "application/x-www-form-urlencoded");
response = await client.SendAsync(request);
response.EnsureSuccessStatusCode();
JSONAutenticacion = await response.Content.ReadAsStringAsync();
}
catch (Exception ex)
{
string sss = ex.ToString();
return null;
}
return response.Content != null ? JsonConvert.DeserializeObject<AutenticacionDTO>(JSONAutenticacion) : new AutenticacionDTO();
}


When I use postman to connect to the web API that I have hosted in my local IIS, there's no problem, same with the console application. But whenever I try to connect with the Xamarin Forms App I get a 400 Bad Request response.

The code that makes the Jwt work goes like this:

public override async Task GrantResourceOwnerCredentials(OAuthGrantResourceOwnerCredentialsContext context)
{
var allowedOrigin = "*";
context.Response.Headers.Add("Access-Control-Allow-Origin", new { allowedOrigin });
Seguridad _Seguridad = new fovissste.bll.Seguridad();
LoginDTO Usuario = _Seguridad.Login(context.UserName, context.Password).FirstOrDefault();

if (Usuario == null)
{
context.SetError("invalid_grant", "Usuario o contraseña incorrectos");
return;
}

ClaimsIdentity oauthIdentity = new ClaimsIdentity(new ApplicationUser(context.UserName, "JWT"), new { new Claim(ClaimTypes.Role, "Publico") });
var ticket = await Task.Run(() => new AuthenticationTicket(oauthIdentity, null));
context.Validated(ticket);
}


Can anybody help? Is this an issue with Xamarin Forms? I truly require some comments because I honestly can't see what I'm missing. I've read other posts in this site that suggest that it can be an issue of enabling remote requests on IIS or a CORS issue but I think that's handled in this line: context.Response.Headers.Add("Access-Control-Allow-Origin", new { allowedOrigin });

context.Response.Headers.Add("Access-Control-Allow-Origin", new { allowedOrigin });

1 Answer
1

Try the following code:

using (var client = new HttpClient())
{
client.BaseAddress = new Uri("http://172.25.1.53:9891");
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

string autenticacion = "?username=" + email + "&password=" + clave + "&grant_type=password";
HttpResponseMessage response = await client.PostAsync(client.BaseAddress + "oauth/secreto", new StringContent(autenticacion, Encoding.UTF8, "application/x-www-form-urlencoded"));

response.EnsureSuccessStatusCode();

string JSONAutenticacion = await response.Content.ReadAsStringAsync();
}


What is the value of Path after this line?

Path

string Path = client.BaseAddress + "oauth/secreto";


Also try to add this line before using (var client... :

using (var client...

System.Net.ServicePointManager.ServerCertificateValidationCallback += (sender, certificate, chain, sslPolicyErrors) => true;


Changed

HttpResponseMessage response = await client.PostAsync(client.BaseAddress + autenticacion, new StringContent(autenticacion));


to

HttpResponseMessage response = await client.PostAsync(client.BaseAddress + "oauth/secreto", new StringContent(autenticacion, Encoding.UTF8, "application/x-www-form-urlencoded"));


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