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Return full HTTP Response in ASP.Net WebAPI Controller

I'm trying to return a full HTTP-Response to the browser within an ASP.NET WebAPI Controller.
The scenario is the following:
I make a remote call to another webserver and get a full HTTP-Message including the HTTP Headers and content. I just want do deliver this message "as is" to the browser.
Does anyone know how to do this?

Create your own IHttpHandler and configure a route for it. You have to copy all response headers from your own response to the response object of ASP.NET.
Here is a sample implementation for another scenario:
public class CorsProxyHttpHandler : IHttpHandler
{
public void ProcessRequest(HttpContext context)
{
var url = context.Request.Headers["X-CorsProxy-Url"];
if (url == null)
{
context.Response.StatusCode = 501;
context.Response.StatusDescription =
"X-CorsProxy-Url was not specified. The corsproxy should only be invoked from the proxy JavaScript.";
context.Response.End();
return;
}
try
{
var request = WebRequest.CreateHttp(url);
context.Request.CopyHeadersTo(request);
request.Method = context.Request.HttpMethod;
request.ContentType = context.Request.ContentType;
request.UserAgent = context.Request.UserAgent;
if (context.Request.AcceptTypes != null)
request.Accept = string.Join(";", context.Request.AcceptTypes);
if (context.Request.UrlReferrer != null)
request.Referer = context.Request.UrlReferrer.ToString();
if (!context.Request.HttpMethod.Equals("GET", StringComparison.OrdinalIgnoreCase))
context.Request.InputStream.CopyTo(request.GetRequestStream());
var response = (HttpWebResponse)request.GetResponse();
response.CopyHeadersTo(context.Response);
context.Response.ContentType = response.ContentType;
context.Response.StatusCode =(int) response.StatusCode;
context.Response.StatusDescription = response.StatusDescription;
var stream = response.GetResponseStream();
if (stream != null && response.ContentLength > 0)
{
stream.CopyTo(context.Response.OutputStream);
stream.Flush();
}
}
catch (WebException exception)
{
context.Response.AddHeader("X-CorsProxy-InternalFailure", "false");
var response = exception.Response as HttpWebResponse;
if (response != null)
{
context.Response.StatusCode = (int)response.StatusCode;
context.Response.StatusDescription = response.StatusDescription;
response.CopyHeadersTo(context.Response);
var stream = response.GetResponseStream();
if (stream != null)
stream.CopyTo(context.Response.OutputStream);
return;
}
context.Response.StatusCode = 501;
context.Response.StatusDescription = exception.Status.ToString();
var msg = Encoding.ASCII.GetBytes(exception.Message);
context.Response.OutputStream.Write(msg, 0, msg.Length);
context.Response.Close();
}
catch (Exception exception)
{
context.Response.StatusCode = 501;
context.Response.StatusDescription = "Failed to call proxied url.";
context.Response.AddHeader("X-CorsProxy-InternalFailure", "true");
var msg = Encoding.ASCII.GetBytes(exception.Message);
context.Response.OutputStream.Write(msg, 0, msg.Length);
context.Response.Close();
}
}
public bool IsReusable { get { return true; }}
}
(from my article: http://blog.gauffin.org/2014/04/how-to-use-cors-requests-in-internet-explorer-9-and-below/)

How do I reissue a webrequest? Must I recreate Webclient?

The following code gets stuck in a while loop when an exception is encountered. This is because GetResponse is caching the data.
According to fiddler, no data after the first request is issued.
Is it a best practice to recreate the webclient to solve the "refresh" issue I'm having?
private static ReportStatusEnum GetReportStatus(string domain, string oAuthKey, long permissionReportID)
{
string target = string.Format("https://{0}.egnyte.com/pubapi/v1/audit/jobs/{1}", domain, permissionReportID);
var client = new WebClient();
string result ="";
var request = (HttpWebRequest)WebRequest.Create(target);
request.ContentType = "application/json";
request.Headers.Add("Authorization", "Bearer " + oAuthKey);
request.AllowAutoRedirect = false;
bool callComplete = false;
while (callComplete != true)
{
try
{
using (var response = request.GetResponse())
{
using (StreamReader reader = new StreamReader(response.GetResponseStream()))
{
result = reader.ReadToEnd();
}
}
JToken result2 = JObject.Parse(result);
var statusResult = result2.SelectToken("status");
ReportStatusEnum ret = ReportStatusEnum.error;
Enum.TryParse<ReportStatusEnum>(statusResult.ToString(), out ret);
Console.WriteLine("The returned variable is:" + ret);
callComplete = true;
return ret;
}
catch (System.Net.WebException e)
{
if (e.Response != null)
if (e.Response.ContentLength > 0)
{
if (e.Response.Headers["X-Mashery-Error-Code"] == "ERR_403_DEVELOPER_OVER_QPS")
{
Thread.Sleep(60000); Console.Write("*QPS HIT*");
}
}
}
}
return ReportStatusEnum.error;
}

No. HttpWebRequests are not reusable.
Just move the creation of your WebRequest into the body of your loop:
string result ="";
bool callComplete = false;
while (callComplete != true)
{
var request = (HttpWebRequest)WebRequest.Create(target);
request.ContentType = "application/json";
request.Headers.Add("Authorization", "Bearer " + oAuthKey);
request.AllowAutoRedirect = false;
//...

Check to see if site is online, limit the timeout

I'm trying to make a function that checks if a site is online or not, but is having some problem with the timeout. I want to limit it to a max 3 sec, if there is no respons within 3 sec I should see the page as offline.
My try:
class OnlineCheck
{
public static bool IsOnline(string url)
{
try
{
WebClient webclient = new WebClient();
webclient.Headers.Add(HttpRequestHeader.KeepAlive, "1000");
webclient.OpenRead(url);
}
catch { return false; }
return true;
}
}

The WebClient doesn't support timeout. But you can use the HttpWebRequest!
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Endpoint);
request.Timeout=3000;
request.GetResponse();

If you want to check that the site is online, you are not really interested in the content of the page, just that you get a response. To make that more efficient, you should only request the http headers. Here is a quick example on how you could do:
private static IEnumerable<HttpStatusCode> onlineStatusCodes = new[]
{
HttpStatusCode.Accepted,
HttpStatusCode.Found,
HttpStatusCode.OK,
// add more codes as needed
};
private static bool IsSiteOnline(string url, int timeout)
{
HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;
{
if (request != null)
{
request.Method = "HEAD"; // get headers only
request.Timeout = timeout;
using (var response = request.GetResponse() as HttpWebResponse)
{
return response != null && onlineStatusCodes.Contains(response.StatusCode);
}
}
}
return false;
}

Use HttpWebRequest rather than WebClient. HttpWebRequest class has a timeout property.

You can try this code:
System.Net.WebRequest r = System.Net.WebRequest.Create("http://www.google.com");
r.Timeout = 3000;
System.Net.WebProxy proxy = new System.Net.WebProxy("<proxy address>");
System.Net.NetworkCredential credentials = new System.Net.NetworkCredential();
credentials.Domain = "<domain>";
credentials.UserName = "<login>";
credentials.Password = "<pass>";
proxy.Credentials = credentials;
r.Proxy = proxy;
try
{
System.Net.WebResponse rsp = r.GetResponse();
}
catch (Exception)
{
MessageBox.Show("Is not avaliable");
return;
}
MessageBox.Show("Avaliable!");

static bool isOnline (string URL)
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(URL);
request.Timeout = 3000;
try
{
WebResponse resp = request.GetResponse();
}
catch (WebException e)
{
if (((HttpWebResponse)e.Response).StatusCode == HttpStatusCode.NotFound)
{
return false;
}
}
return true;
}

How to check if remote image exists with C#

public void BuildImg()
{
// The two different images as strings.
string url1 = "http://remoteimage.com/image.jpg";
string url2 = "http://remoteimage.com/image2.jpg";
try
{
// Check to see if url1 exists or not
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url1);
request.Credentials = System.Net.CredentialCache.DefaultCredentials;
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
myImg.Visible = true;
myImg.ImageUrl = url1;
}
catch (Exception ex)
{
// Check to see if url2exists or not
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url2);
request.Credentials = System.Net.CredentialCache.DefaultCredentials;
HttpWebResponse response;
try
{
response = request.GetResponse() as HttpWebResponse;
}
catch (WebException exc)
{
response = exc.Response as HttpWebResponse;
}
// Set myImg to show if url2 exists
myImg.Visible = true;
myImg.ImageUrl = url2;
// If response returns 404, then hide myImg
if (response.StatusCode == HttpStatusCode.NotFound)
{
myImg.Visible = false;
}
}

var arr = new[]
{
"http://example.com/image.jpg",
"http://example.com/image2.jpg"
...
};
myImg.ImageUrl = arr.FirstOrDefault(i => CheckExistence(i));
static bool CheckUrlExistence(string url)
{
try
{
var request = (HttpWebRequest)WebRequest.Create(url);
request.Credentials = CredentialCache.DefaultCredentials;
request.Method = "HEAD";
var response = (HttpWebResponse)request.GetResponse();
return response.StatusCode == HttpStatusCode.OK;
}
catch (Exception ex)
{
var code = ((HttpWebResponse)((WebException)ex).Response).StatusCode; // NotFound, etc
return false;
}

can I check if a file exists at a URL?

I know I can locally, on my filesystem, check if a file exists:
if(File.Exists(path))
Can I check at a particular remote URL?

If you're attempting to verify the existence of a web resource, I would recommend using the HttpWebRequest class. This will allow you to send a HEAD request to the URL in question. Only the response headers will be returned, even if the resource exists.
var url = "http://www.domain.com/image.png";
HttpWebResponse response = null;
var request = (HttpWebRequest)WebRequest.Create(url);
request.Method = "HEAD";
try
{
response = (HttpWebResponse)request.GetResponse();
}
catch (WebException ex)
{
/* A WebException will be thrown if the status of the response is not `200 OK` */
}
finally
{
// Don't forget to close your response.
if (response != null)
{
response.Close();
}
}
Of course, if you want to download the resource if it exists it would most likely be more efficient to send a GET request instead (by not setting the Method property to "HEAD", or by using the WebClient class).

If you want to just copy & paste Justin's code and get a method to use, here's how I've implemented it:
using System.Net;
public class MyClass {
static public bool URLExists (string url) {
bool result = false;
WebRequest webRequest = WebRequest.Create(url);
webRequest.Timeout = 1200; // miliseconds
webRequest.Method = "HEAD";
HttpWebResponse response = null;
try {
response = (HttpWebResponse)webRequest.GetResponse();
result = true;
} catch (WebException webException) {
Debug.Log(url +" doesn't exist: "+ webException.Message);
} finally {
if (response != null) {
response.Close();
}
}
return result;
}
}
I'll keep his observation:
If you want to download the resource, and it exists, it would be more efficient to send a GET request instead by not setting the Method property to "HEAD" or by using the WebClient class.

Below is a simplified version of the code:
public bool URLExists(string url)
{
bool result = true;
WebRequest webRequest = WebRequest.Create(url);
webRequest.Timeout = 1200; // miliseconds
webRequest.Method = "HEAD";
try
{
webRequest.GetResponse();
}
catch
{
result = false;
}
return result;
}

If you are using a unc path or a mapped drive, this will work fine.
If you are using a web address (http, ftp etc) you are better off using WebClient - you will get a WebException if it doesn't exist.

public static bool UrlExists(string file)
{
bool exists = false;
HttpWebResponse response = null;
var request = (HttpWebRequest)WebRequest.Create(file);
request.Method = "HEAD";
request.Timeout = 5000; // milliseconds
request.AllowAutoRedirect = false;
try
{
response = (HttpWebResponse)request.GetResponse();
exists = response.StatusCode == HttpStatusCode.OK;
}
catch
{
exists = false;
}
finally
{
// close your response.
if (response != null)
response.Close();
}
return exists;
}

I had the same problem to solve in asp.net core, I've solved with HttpClient
private async Task<bool> isFileExist(string url)
{
using (HttpClient client = new HttpClient())
{
var restponse = await client.GetAsync(url);
return restponse.StatusCode == System.Net.HttpStatusCode.OK;
}
}

My version:
public bool IsUrlExist(string url, int timeOutMs = 1000)
{
WebRequest webRequest = WebRequest.Create(url);
webRequest.Method = "HEAD";
webRequest.Timeout = timeOutMs;
try
{
var response = webRequest.GetResponse();
/* response is `200 OK` */
response.Close();
}
catch
{
/* Any other response */
return false;
}
return true;
}

WebRequest will waiting long time(ignore the timeout user set) because not set proxy, so I change to use RestSharp to do this.
var client = new RestClient(url);
var request = new RestRequest(Method.HEAD);
request.Timeout = 5000;
var response = client.Execute(request);
result = response.StatusCode == HttpStatusCode.OK;

Thanks for all answers.
And I would like to add my implementation which includes default state when we get errors, for specific cases like mine.
private bool HTTP_URLExists(String vstrURL, bool vResErrorDefault = false, int vTimeOut = 1200)
{
bool vResult = false;
WebRequest webRequest = WebRequest.Create(vstrURL);
webRequest.Timeout = vTimeOut; // miliseconds
webRequest.Method = "HEAD";
HttpWebResponse response = null;
try
{
response = (HttpWebResponse)webRequest.GetResponse();
if (response.StatusCode == HttpStatusCode.OK) vResult = true;
else if (response.StatusCode == HttpStatusCode.NotFound) vResult = false;
else vResult = vResErrorDefault;
}
catch (WebException ex)
{
if (ex.Status == WebExceptionStatus.ProtocolError && ex.Response != null)
{
var resp01 = (HttpWebResponse)ex.Response;
if (resp01.StatusCode == HttpStatusCode.NotFound)
{
vResult = false;
}
else
{
vResult = vResErrorDefault;
}
}
else
{
vResult = vResErrorDefault;
}
}
finally
{
// Don't forget to close your response.
if (response != null)
{
response.Close();
}
}
return vResult;
}

Anoter version with define timeout :
public bool URLExists(string url,int timeout = 5000)
{
...
webRequest.Timeout = timeout; // miliseconds
...
}

This works for me:
bool HaveFile(string url)
{
try
{
using (WebClient webClient = new WebClient())
{
webClient.DownloadString(url);
}
return true;
}
catch (Exception)
{
return false;
}
}