Basic Authentication with Resteasy client - basic-authentication

I'm trying to perform an basic auth to the login-module which runs on my jboss using REST. I already found an StackOverflow topic which explains how to authenticate with credentials.
RESTEasy client framework authentication credentials
This does not work. Analysing the established connection with Wireshark I was not able to see an HTTP package with Authorization: Basic. After more research I found this article, http://docs.jboss.org/resteasy/docs/2.3.3.Final/userguide/html/RESTEasy_Client_Framework.html which describes how to append basic auth to ApacheHttpClient4Executor from resteasy.
// Configure HttpClient to authenticate preemptively
// by prepopulating the authentication data cache.
// 1. Create AuthCache instance
AuthCache authCache = new BasicAuthCache();
// 2. Generate BASIC scheme object and add it to the local auth cache
BasicScheme basicAuth = new BasicScheme();
authCache.put("com.bluemonkeydiamond.sippycups", basicAuth);
// 3. Add AuthCache to the execution context
BasicHttpContext localContext = new BasicHttpContext();
localContext.setAttribute(ClientContext.AUTH_CACHE, authCache);
// 4. Create client executor and proxy
httpClient = new DefaultHttpClient();
ApacheHttpClient4Executor executor = new ApacheHttpClient4Executor(httpClient, localContext);
client = ProxyFactory.create(BookStoreService.class, url, executor);
But this does not work either. There is no description how to append username and passwort for basic auth to the construct. Why is that information not associated with any class from httpcomponent?

One can use org.jboss.resteasy.client.jaxrs.BasicAuthentication which is packaged with resteasy-client 3.x and is meant specifically for basic authentication.
Client client = ClientBuilder.newClient();
ResteasyWebTarget resteasyWebTarget = (ResteasyWebTarget)client.target("http://mywebservice/rest/api");
resteasyWebTarget.register(new BasicAuthentication("username", "passwd"));

You can add a raw authorization header to your REST client by invoking .header(HttpHeaders.AUTHORIZATION, authHeader) in your client configuration.
The credentials must be packed in authorization header in the format of "user:pass", encoded as base64 byte array and then appended to the string "Basic " which identifies basic auth.
This is the whole snippet (inspired by this post on baeldung)
String auth = userName + ":" + password;
byte[] encodedAuth = Base64.encodeBase64(auth.getBytes(Charset.forName("ISO-8859-1")));
String authHeader = "Basic " + new String(encodedAuth);
authToken = restClient.target(restApiUrl + loginPath)
.request()
.accept(MediaType.TEXT_PLAIN)
.header(HttpHeaders.AUTHORIZATION, authHeader)
.get(String.class);
This worked for me in a Resteasy client. For information, when testing this with wget I had to use the --auth-no-challenge flag.

Consider the solution from Adam Bien:
You can attach an ClientRequestFilter to the RESTEasy Client, which adds the Authorization header to the request:
public class Authenticator implements ClientRequestFilter {
private final String user;
private final String password;
public Authenticator(String user, String password) {
this.user = user;
this.password = password;
}
public void filter(ClientRequestContext requestContext) throws IOException {
MultivaluedMap<String, Object> headers = requestContext.getHeaders();
final String basicAuthentication = getBasicAuthentication();
headers.add("Authorization", basicAuthentication);
}
private String getBasicAuthentication() {
String token = this.user + ":" + this.password;
try {
return "Basic " +
DatatypeConverter.printBase64Binary(token.getBytes("UTF-8"));
} catch (UnsupportedEncodingException ex) {
throw new IllegalStateException("Cannot encode with UTF-8", ex);
}
}
}
Client client = ClientBuilder.newClient()
.register(new Authenticator(user, password));

I recently upgraded to resteasy-client:4.0.0.Final to deal with some Jackson upgrade issues, and I noticed that setting headers seem to work differently (I was getting 401: Authorization Errors for every authenticated request that previously worked). I also couldn't find much documentation, (the 4.0.0.Final release is only a month old and has some dependency issues, if my experience is representative of the broader case).
The code previously injected headers into the ClientRequestContext:
public AddAuthHeadersRequestFilter(String username, String password) {
this.username = username;
this.password = password;
}
#Override
public void filter(ClientRequestContext requestContext) throws IOException {
String token = username + ":" + password;
String base64Token = Base64.encodeString(token);
requestContext.getHeaders().add("Authorization", "Basic " + base64Token);
}
}
then we set the filter on the ResteasyClient like so:
ResteasyClient client = new ResteasyClientBuilder()
.sslContext(buildSSLContext())
.hostnameVerifier(buildHostVerifier())
.build();
client.register(new AddAuthHeadersRequestFilter(user, pass));
However, this appears not to set the HeaderDelegate, which is where headers are retrieved in 4.x(?) and possibly earlier versions.
The trick was to register that filter on the ResteasyWebTarget instead of the client in the 4.0.0.Final version (you may notice the clientBuilder works a little differently now too).
ResteasyClient client = (ResteasyClient)ResteasyClientBuilder.newBuilder()
.sslContext(buildSSLContext())
.hostnameVerifier(buildHostVerifier())
.build();
ResteasyWebTarget target = client.target(url);
target.register(new AddAuthHeadersRequestFilter(user, pass));

Related

Thirdparty certificate authentication in .net core API between client and server API

I am trying to implement the certificate authentication in .net core API(Server/target) and this API will be invoked in to another API(Client) .Here is the piece of code of client api which makes request to server/target api.But I'm facing an error on the server/target api .I'm running these two services from local and both certificates have already installed
Client side controller logic
[HttpGet]
public async Task<List<WeatherForecast>> Get()
{
List<WeatherForecast> weatherForecastList = new List<WeatherForecast>();
X509Certificate2 clientCert = Authentication.GetClientCertificate();
if (clientCert == null)
{
HttpActionContext actionContext = null;
actionContext.Response = new HttpResponseMessage(System.Net.HttpStatusCode.Forbidden)
{
ReasonPhrase = "Client Certificate Required"
};
}
HttpClientHandler requestHandler = new HttpClientHandler();
requestHandler.ClientCertificates.Add(clientCert);
requestHandler.ServerCertificateCustomValidationCallback += (sender, cert, chain, sslPolicyErrors) => true;
HttpClient client = new HttpClient(requestHandler)
{
BaseAddress = new Uri("https://localhost:11111/ServerAPI")
};
client.DefaultRequestHeaders
.Accept
.Add(new MediaTypeWithQualityHeaderValue("application/xml"));//ACCEPT head
using (var httpClient = new HttpClient())
{
//httpClient.DefaultRequestHeaders.Accept.Clear();
var request = new HttpRequestMessage()
{
RequestUri = new Uri("https://localhost:44386/ServerAPI"),
Method = HttpMethod.Get,
};
request.Headers.Add("X-ARR-ClientCert", clientCert.GetRawCertDataString());
httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));//ACCEPT head
//using (var response = await httpClient.GetAsync("https://localhost:11111/ServerAPI"))
using (var response = await httpClient.SendAsync(request))
{
if (response.StatusCode == System.Net.HttpStatusCode.OK)
{
string apiResposne = await response.Content.ReadAsStringAsync();
weatherForecastList = JsonConvert.DeserializeObject<List<WeatherForecast>>(apiResposne);
}
}
}
return weatherForecastList;
}
authentication class
public static X509Certificate2 GetClientCertificate()
{
X509Store userCaStore = new X509Store(StoreName.TrustedPeople, StoreLocation.CurrentUser);
try
{
string str_API_Cert_Thumbprint = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";
userCaStore.Open(OpenFlags.ReadOnly);
X509Certificate2Collection certificatesInStore = userCaStore.Certificates;
X509Certificate2Collection findResult = certificatesInStore.Find(X509FindType.FindByThumbprint, str_API_Cert_Thumbprint, false);
X509Certificate2 clientCertificate = null;
if (findResult.Count == 1)
{
clientCertificate = findResult[0];
if(System.DateTime.Today >= System.Convert.ToDateTime(clientCertificate.GetExpirationDateString()))
{
throw new Exception("Certificate has already been expired.");
}
else if (System.Convert.ToDateTime(clientCertificate.GetExpirationDateString()).AddDays(-30) <= System.DateTime.Today)
{
throw new Exception("Certificate is about to expire in 30 days.");
}
}
else
{
throw new Exception("Unable to locate the correct client certificate.");
}
return clientCertificate;
}
catch (Exception ex)
{
throw;
}
finally
{
userCaStore.Close();
}
}
Server/target api code
[HttpGet]
public IEnumerable<WeatherForecast> Getcertdata()
{
IHeaderDictionary headers = base.Request.Headers;
X509Certificate2 clientCertificate = null;
string certHeaderString = headers["X-ARR-ClientCert"];
if (!string.IsNullOrEmpty(certHeaderString))
{
//byte[] bytes = Encoding.ASCII.GetBytes(certHeaderString);
//byte[] bytes = Convert.FromBase64String(certHeaderString);
//clientCertificate = new X509Certificate2(bytes);
clientCertificate = new X509Certificate2(WebUtility.UrlDecode(certHeaderString));
var serverCertificate = new X509Certificate2(Path.Combine("abc.pfx"), "pwd");
if (clientCertificate.Thumbprint == serverCertificate.Thumbprint)
{
//Valida Cert
}
}
var rng = new Random();
return Enumerable.Range(1, 5).Select(index => new WeatherForecast
{
Date = DateTime.Now.AddDays(index),
TemperatureC = rng.Next(-20, 55),
Summary = Summaries[rng.Next(Summaries.Length)]
}).ToArray();
//return new List<WeatherForecast>();
}
You have much more problems here, the code is significantly flawed and insecure in various ways. Let's explain each issue:
HttpClient in using clause in client side controller logic
Although you expect to wrap anything that implements IDisposable in using statement. However, it is not really the case with HttpClient. Connections are not closed immediately. And with every request to client controller action, a new connection is established to remote endpoint, while previous connections sit in TIME_WAIT state. Under certain constant load, your HttpClient will exhaust TCP port pool (which is limited) and any new attempt to create a new connection will throw an exception. Here are more details on this problem: You're using HttpClient wrong and it is destabilizing your software
Microsoft recommendation is to re-use existing connections. One way to do this is to Use IHttpClientFactory to implement resilient HTTP requests. Microsoft article talks a bit about this problem:
Though this class implements IDisposable, declaring and instantiating
it within a using statement is not preferred because when the
HttpClient object gets disposed of, the underlying socket is not
immediately released, which can lead to a socket exhaustion problem.
BTW, you have created a client variable, but do not use it in any way.
Ignore certificate validation problems
The line:
requestHandler.ServerCertificateCustomValidationCallback += (sender, cert, chain, sslPolicyErrors) => true;
make you vulnerable to MITM attack.
you are doing client certificate authentication wrong
The line:
request.Headers.Add("X-ARR-ClientCert", clientCert.GetRawCertDataString());
It is not the proper way how to do client cert authentication. What you literally doing is passing certificate's public part to server. That's all. You do not prove private key possession which is required to authenticate you. The proper way to do so is:
requestHandler.ClientCertificates.Add(clientCert);
This will force client and server to perform proper client authentication and check if you possess the private key for certificate you pass (it is done in TLS handshake automatically). If you have ASP.NET on server side, then you read it this way (in controller action):
X509Certificate2 clientCert = Request.HttpContext.Connection.ClientCertificate
if (clientCert == null) {
return Unauthorized();
}
// perform client cert validation according server-side rules.
Non-standard cert store
In authentication class you open StoreName.TrustedPeople store, while normally it should be StoreName.My. TrustedPeople isn't designed to store certs with private key. It isn't a functional problem, but it is bad practice.
unnecessary try/catch clause in authentication class
If you purposely throw exceptions in method, do not use try/catch. In your case you simply rethrow exception, thus you are doing a double work. And this:
throw new Exception("Certificate is about to expire in 30 days.");
is behind me. Throwing exception on technically valid certificate? Really?
server side code
As said, all this:
IHeaderDictionary headers = base.Request.Headers;
X509Certificate2 clientCertificate = null;
string certHeaderString = headers["X-ARR-ClientCert"];
if (!string.IsNullOrEmpty(certHeaderString))
{
//byte[] bytes = Encoding.ASCII.GetBytes(certHeaderString);
//byte[] bytes = Convert.FromBase64String(certHeaderString);
//clientCertificate = new X509Certificate2(bytes);
clientCertificate = new X509Certificate2(WebUtility.UrlDecode(certHeaderString));
var serverCertificate = new X509Certificate2(Path.Combine("abc.pfx"), "pwd");
if (clientCertificate.Thumbprint == serverCertificate.Thumbprint)
{
//Valida Cert
}
}
must be replaced with:
X509Certificate2 clientCert = Request.HttpContext.Connection.ClientCertificate
if (clientCert == null) {
return Unauthorized();
}
// perform client cert validation according server-side rules.
BTW:
var serverCertificate = new X509Certificate2(Path.Combine("abc.pfx"), "pwd");
if (clientCertificate.Thumbprint == serverCertificate.Thumbprint)
{
//Valida Cert
}
This is another disaster in your code. You are loading the server certificate from PFX just to compare their thumbprints? So, you suppose that client will have a copy of server certificate? Client and server certificates must not be the same. Next thing is you are generating a lot of copies of server certificate's private key files. More private key files you generate, the slower the process is and you just generate a lot of garbage. More details on this you can find in my blog post: Handling X509KeyStorageFlags in applications

Spring Security form post authentication

I have a page to access with form post request (webview page for mobile apps). My application can't have a login form but I need to secure it. Mobile applications will call this webview page with authentication parameters such as (email/password). I need to call third-party api with given authentication parameters and decide it was authenticated or not. Which approach should I use for my scenarios ?
If it possible to pass authentication parameters in the Authorization header, you can enable http basic authentication in your application:
#Override
public void configure(HttpSecurity http) throws Exception {
http
.authorizeRequests()
.anyRequest()
.authenticated()
.and()
.httpBasic();
}
Otherwise, you can implement your own security filter to create a UsernamePasswordAuthenticationToken (or any other class implementing Authentication) instance from your specific authentication parameters and pass to AuthenticationManager; but in the case of another class, you need to make the authentication provider below support it by overriding the public boolean supports(Class<?> authentication) method.
Then implement a custom AuthenticationProvider that will delegate authentication to the third-party API, e.g.:
public class RestAuthenticationProvider extends AbstractUserDetailsAuthenticationProvider {
private static final String AUTH_URL = "http://third-party-service/authentication/basic";
private RestTemplate restTemplate;
public RestAuthenticationProvider() {
this.restTemplate = new RestTemplate();
}
#Override
protected void additionalAuthenticationChecks(UserDetails userDetails, UsernamePasswordAuthenticationToken authentication) throws AuthenticationException {
if (authentication.getCredentials() == null) {
this.logger.debug("Authentication failed: no credentials provided");
throw new BadCredentialsException(this.messages.getMessage("AbstractUserDetailsAuthenticationProvider.badCredentials", "Bad credentials"));
}
if (!authentication.getCredentials().toString().equals(userDetails.getPassword())) {
this.logger.debug("Authentication failed: invalid credentials");
throw new BadCredentialsException(this.messages.getMessage("AbstractUserDetailsAuthenticationProvider.badCredentials", "Bad credentials"));
}
}
#Override
protected UserDetails retrieveUser(String username, UsernamePasswordAuthenticationToken authentication) {
String password = authentication.getCredentials().toString();
try {
ResponseEntity<String> authenticationResponse = authenticate(username, password);
if (authenticationResponse.getStatusCode().value() == 401) {
throw new BadCredentialsException(this.messages.getMessage("AbstractUserDetailsAuthenticationProvider.badCredentials", "Bad credentials"));
}
return createUser(authenticationResponse.getBody());
} catch (BadCredentialsException ex) {
throw ex;
} catch (Exception ex) {
throw new InternalAuthenticationServiceException(ex.getMessage(), ex);
}
}
private ResponseEntity<String> authenticate(String username, String password) {
HttpEntity entity = new HttpEntity(createHeaders(username, password));
return restTemplate.exchange(AUTH_URL, HttpMethod.GET, entity, String.class);
}
private HttpHeaders createHeaders(String username, String password) {
HttpHeaders headers = new HttpHeaders();
headers.set("Content-Type", "application/json");
String authorization = username + ":" + password;
String basic = Base64.getEncoder().encodeToString(authorization.getBytes());
headers.set("Authorization", "Basic " + basic);
return headers;
}
private UserDetails createUser(String json) {
return null; // TODO: Implement
}
}
And finally, make Spring Security to use your provider:
#Override
protected void configure(AuthenticationManagerBuilder auth) {
auth.authenticationProvider(new RestAuthenticationProvider())
.eraseCredentials(false);
}
I need to call third-party api with given authentication parameters
and decide it was authenticated or not
Assuming you need to use username / password to send to 3rd party, when you first login into the app, you can create a long lived token in back-end and sent it to the app to store in secure store. Later when you want to load the protected webview, send this token along with the request (in header or body via javascript) and in the server side pick the user / password corresponding to the token and authenticate with 3rd party.
This way you will never need to store password on client side and you can manually make the token at backend inactive too. If you like to go standard way, then you may take a look at Password Grant of OAuth 2 / OpenID Connect / . With the correct infrastructure in place you can get access tokens during login process and use that for your protected page. Spring Security has support for this flow - you can take a look here.

Spring OAuth2 - URL Encoded of username within Basic auth header for token endpoint

It seems that Basic Auth for token endpoint is not compliant with OAuth2.0 spec, which specifies that the username and password should be URL encoded before being joined with a colon and the base 64 encoded. See rfc6749
Creation of the header should be:
auth_header = 'Basic' + base64 (urlEncode (client_id) + ':' + urlEncode (client_secret))
Hence there needs a URL decode step after splitting the username from the password.
Spring is just using the BasicAuthenticationFilter to extract the credentials and there doesn't seem a way of extending this to add the URL Decode step.
So, is this an omission from Spring security OAuth2? If so, guess a bug should be raised.
I could replace the BasicAuthenticationFilter, with one that has the URL Decode step, but is there an easier way?
I am currently using Spring Security 5.0.5
Spring security does comply with OAuth 2.0 spec. What you're asking is already covered in BasicAuthenticationFilter. Here's an excerpt from the code:
protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain chain) throws IOException, ServletException {
boolean debug = this.logger.isDebugEnabled();
String header = request.getHeader("Authorization");
if (header != null && header.startsWith("Basic ")) {
try {
String[] tokens = this.extractAndDecodeHeader(header, request);
assert tokens.length == 2;
Filter reads the header that has Basic authentication, then it extracts and decode the credentials.
In the following code, notice that index of colon is used as a String delimiter.
private String[] extractAndDecodeHeader(String header, HttpServletRequest request) throws IOException {
byte[] base64Token = header.substring(6).getBytes("UTF-8");
byte[] decoded;
try {
decoded = Base64.getDecoder().decode(base64Token);
} catch (IllegalArgumentException var7) {
throw new BadCredentialsException("Failed to decode basic authentication token");
}
String token = new String(decoded, this.getCredentialsCharset(request));
int delim = token.indexOf(":");
if (delim == -1) {
throw new BadCredentialsException("Invalid basic authentication token");
} else {
return new String[]{token.substring(0, delim), token.substring(delim + 1)};
}
}

Using Hammock to Call Recurly REST API with BasicAuthCredentials

I'm trying to call the Recurly REST API using the Hammock C# library for .NET. The API calls require an Authorization header on the HttpRequest, and the authentication scheme is Basic authentication with the Base64 encoded API key in the username portion of the header. I thought that I could create a new Hammock BasicAuthCredentials object with the encoded key in the Username property of the object, then assign the object to the Credentials property of either the RestClient or RestRequest objects. However, this does not seem to generate an Authorization header on the outbound HttpRequest.
If I add the Authorization header manually using the AddHeader method on one of those objects, the API call succeeds. If I use the Credentials property with the BasicAuthCredentials object, I get an Access Denied error from Recurly.
This seems pretty basic, so I know I'm doing something wrong. So, in Hammock, is the Credentials property on either the RestClient or RestRequest object supposed to create an Authorization header on the Http request?
Thanks for any help from a super Hammock user!
The code that fails:
class Program
{
public static void Main(string[] args)
{
string encodedAPIKey = Convert.ToBase64String(Encoding.UTF8.GetBytes("APIKeyHere"));
BasicAuthCredentials credentials = new BasicAuthCredentials
{
Username = encodedAPIKey
};
RestClient client = new RestClient
{
Authority = "https://api.recurly.com",
VersionPath = "v2"
};
client.AddHeader("Accept", "application/xml");
RestRequest request = new RestRequest
{
Credentials = credentials,
Path = "plans"
};
RestResponse response = client.Request(request);
Console.WriteLine(response.Content);
Console.ReadLine();
}
}
The code that succeeds:
class Program
{
public static void Main(string[] args)
{
string encodedAPIKey = Convert.ToBase64String(Encoding.UTF8.GetBytes("APIKeyHere"));
RestClient client = new RestClient
{
Authority = "https://api.recurly.com",
VersionPath = "v2"
};
client.AddHeader("Accept", "application/xml");
client.AddHeader("Authorization", "Basic " + encodedAPIKey);
RestRequest request = new RestRequest
{
Path = "plans"
};
RestResponse response = client.Request(request);
Console.WriteLine(response.Content);
Console.ReadLine();
}
}
After getting no answers to my question, I did a search for alternative Rest libraries for .NET and found RestSharp. I was able to get it working with Recurly using its built-in Basic Authorization implementation on the first try, so I will be implementing using RestSharp. The code looks very similar, so the migration should be an easy one.

Securing ASP.NET MVC controller action which returns JSON

I have an MVC3 application, and my controller actions are secured using the [Authorize] attribute. So far, so good, forms auth works great. Now I want to add a JSON API to my application so some actions are accessible to non-browser clients.
I'm having trouble figuring out the 'right' design.
1) Each user has secret API key.
2) User ID 5 calls http://myapp.com/foocontroller/baraction/5?param1=value1&param2=value2&secure_hash=someValue. Here, secure_hash is simply the SHA1 hash of param1 and param2's values appended with the secret API key for the user
2) /foocontroller/baraction will be decorated with [CustomAuthorize]. This will be an implementation of AuthorizeAttribute which will check if the request is coming in as JSON. If it is, it will check the hash and see if it matches. Otherwise, if the request is HTML, then I call into existing authorization.
I am not at all sure if this will work. Is it normal to pass a secure hash in the query string or should I be passing it in as an HTTP header? Is it better to use HTTP basic auth instead of a hash made using the secret API key?
Tips from anyone who has made a web API using ASP.NET MVC would be welcome!
I pass the secret API key along with username and password in the request body. Once authorized, a token is generated and the client has to pass that in the Authorization header. This gets checked in the base controller on each request.
Client calls myapp.com/authorize which return auth token.
Client stores auth token locally.
Client calls myapp.com/anycontroller, with authtoken in Authorization header.
AuthorizeController inherits from controller.
Anycontroller inherits from a custom base controller which performs the authorization code.
My example requires the following route which directs POST requests to an ActionResult named post in any controller. I am typing this in by hand to simplify it as much as possible to give you the general idea. Don't expect to cut and paste and have it work :)
routes.MapRoute(
"post-object",
"{controller}",
new { controller = "Home", action = "post" {,
new { httpMethod = new HttpMethodConstraint("POST")}
);
Your auth controller can use this
public class AuthorizationController : Controller
{
public ActionResult Post()
{
string authBody;
var request = ControllerContext.HttpContext.Request;
var response = ControllerContext.HttpContext.Response;
using(var reader = new StreamReader(request.InputStream))
authBody = reader.ReadToEnd();
// authorize based on credentials passed in request body
var authToken = {result of your auth method}
response.Write(authToken);
}
}
Your other controllers inherit from a base controller
public class BaseController : Controller
{
protected override void Execute(RequestContext requestContext)
{
var request = requestContext.HttpContext.Request;
var response = requestContext.HttpContext.Response;
var authToken = Request.Headers["Authorization"];
// use token to authorize in your own method
var authorized = AmIAuthorized();
if(authorized = false) {
response.StatusCode = 401;
response.Write("Invalid token");
return;
}
response.StatusCode = 200; // OK
base.Execute(requestContext); // allow inheriting controller to continue
}
}
Sample code to call the api
public static void ExecutePostRequest(string contentType)
{
request = (HttpWebRequest)WebRequest.Create(Uri + Querystring);
request.Method = "POST";
request.ContentType = contentType; // application/json usually
request.Headers["Authorization"] = token;
using (StreamWriter writer = new StreamWriter(request.GetRequestStream()))
writer.Write(postRequestData);
// GetResponse reaises an exception on http status code 400
// We can pull response out of the exception and continue on our way
try
{
response = (HttpWebResponse)request.GetResponse();
}
catch (WebException ex)
{
response = (HttpWebResponse)ex.Response;
}
finally
{
using (StreamReader reader =
new StreamReader(response.GetResponseStream()))
responseText = reader.ReadToEnd();
httpcontext = HttpContext.Current;
}
}

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