HttpWebRequest response produces HTTP 422. Why?
Solution 1
Ok I've got it guys.
I had two problems.
-
HTTP 1.1/ 100 continue
I solved this by setting
System.Net.ServicePointManager.Expect100Continue = false;
-
The server repsonded with 422 because of a problem related to the cookies. The POST request needs to transmit a cookie container, that contains a cookie with the current session id. If this session id is not transmitted, the Server will respond with 422. In order to be able to have a cookie with the session id, I had to perform a simple HTTP-request on the login page. This request returned a cookie container with the needed session id. Then I passed the returned cookie container to POST request.
//cookie container of previous request postRequest.CookieContainer = cookieContainer;
With this settings the POST request could be sent successfully.
Thanks for your help.
Solution 2
You don't seem to be escaping the = and @ correctly. Not sure if that's the only issue.
You can try HttpUtility.UrlEncode.
Simon
M. Sc. in Computer Science at KIT (Karlsruhe Institut of Technology) Data Engineer / Software Engineer Freelancer
Updated on June 04, 2022Comments
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Simon almost 2 years
I'm trying to programmatically send a POST-request to a web-server in order to login an then perform other requests that require a login.
This is my code:
byte[] data = Encoding.UTF8.GetBytes( String.Format( "login={0}&password={1}&authenticity_token={2}" +"&login_submit=Entra&remember_me=1", HttpUtility.UrlEncode(username), HttpUtility.UrlEncode(password), HttpUtility.UrlEncode(token))); //Create HTTP-request for login HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create("http://www.xxx.xx/xx/xx"); request.Method = "POST"; request.ContentType = "application/x-www-form-urlencoded"; request.ContentLength = data.Length; request.CookieContainer = new CookieContainer(); request.Accept = "application/xml,application/xhtml+xml,text/html; +"q=0.9,text/plain ;q=0.8,image/png,*/*;q=0.5"; request.Referer = "http://www.garzantilinguistica.it/it/session"; request.Headers.Add("Accept-Language", "de-DE"); request.Headers.Add("Origin", "http://www.xxx.xx"); request.UserAgent = "C#"; request.Headers.Add("Accept-Encoding", "gzip, deflate");
After sending the request
//Send post request var requestStream = request.GetRequestStream(); requestStream.Write(data, 0, data.Length); requestStream.Flush(); requestStream.Close();
... I want to get the servers response:
//Get Response StreamReader responseStreamReader = new StreamReader( request.GetResponse().GetResponseStream()); //WebException: HTTP 422! string content = responseStreamReader.ReadToEnd();
This piece of code fires the WebException, that tells me the server responded with HTTP 422 (unprocessable entity due to semantic errors)
Then I compared (using a TCP/IP sniffers) the requests of my program and the browser (which of course produces a valid POST-request and gets the right response).
(1) My program's request:
POST /it/session HTTP/1.1 Content-Type: application/x-www-form-urlencoded Accept: application/xml,application/xhtml+xml,text/html; q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5 Referer: http://www.garzantilinguistica.it/it/session Accept-Language: de-DE Origin: http://www.garzantilinguistica.it User-Agent: Test Accept-Encoding: gzip, deflate Host: www.garzantilinguistica.it Content-Length: 148 Expect: 100-continue Connection: Keep-Alive HTTP/1.1 100 Continue login=thespider14%40hotmail.com&password=xxxxx&authenticity_token=4vLgtwP3nFNg4NeuG4MbUnU7sy4z91Wi8WJXH0POFmg%3d&login_submit=Entra&remember_me=1
(2) The browser's request:
POST /it/session HTTP/1.1 Host: www.garzantilinguistica.it Referer: http://www.garzantilinguistica.it/it/session Accept: application/xml,application/xhtml+xml,text/html;q=0.9, text/plain;q=0.8,image/png,*/*;q=0.5 Accept-Language: de-DE Origin: http://www.garzantilinguistica.it User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de-DE) AppleWebKit/531.22.7 (KHTML, like Gecko) Version/4.0.5 Safari/531.22.7 Accept-Encoding: gzip, deflate Content-Type: application/x-www-form-urlencoded Cookie: __utma=244184339.652523587.1275208707.1275208707.1275211298.2; __utmb=244184339.20.10.1275211298; __utmc=244184339; __utmz=244184339.1275208707.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); _garzanti2009_session=BAh7CDoPc2Vzc2lvbl9pZCIlZDg4MWZjNjg2YTRhZWE0NDQ0ZTJmMTU2YWY4ZTQ1NGU6EF9jc3JmX3Rva2VuIjFqRWdLdll3dTYwOTVVTEpNZkt6dG9jUCtaZ0o4V0FnV2V5ZnpuREx6QUlZPSIKZmxhc2hJQzonQWN0aW9uQ29udHJvbGxlcjo6Rmxhc2g6OkZsYXNoSGFzaHsGOgplcnJvciIVbG9naW4gbm9uIHZhbGlkbwY6CkB1c2VkewY7CFQ%3D--4200fa769898dd156faa49e457baf660cf068d08 Content-Length: 144 Connection: keep-alive authenticity_token=jEgKvYwu6095ULJMfKztocP%2BZgJ8WAgWeyfznDLzAIY%3D&login=thespider14%40hotmail.com&password=xxxxxx&remember_me=1&commit=Entra HTTP/1.1 302 Found
Can someone help to understand which part of the request I am missing or what the main difference between the browser's and my request is? Why am I getting that 422?
EDIT:
I noticed that my request contains a
Expect
header with the value 100-continue, whereas the browser's doesn't. I set therequest.Expect
-property tonull
and to""
. But I just couldn't get rid of it. Any suggestions? May this be the root of all evil?EDIT:
Finally I removed the
Expect
-Header. But it didn't help. Any ideas? I activated the CookieContainer by settingrequest.CookieContainer = new CookieContainer();
But I can't see the Cookie-Header in the HTTP-trace. Why?