Develop Reference

GDax API GET request always returns Error 400

I'm trying to get the order book from GDAX (link to documentation of the call) but when doing it from the c# executable I always get Error 400 - Bad request.
When taking the actual URL and pasting it into my browser, it works fine.
String URL = "https://api.gdax.com/products/BTC-USD/book?level=2";
WebRequest request = WebRequest.Create(URL);
WebResponse response = request.GetResponse();

The actual issue with your API call is , the API is expecting a user-agent string while making the request: Below is the code in working condition:
try
{
String URL = "http://api.gdax.com/products/BTC-USD/book?level=2";
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(URL);
request.UserAgent = ".NET Framework Test Client";
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
var encoding = ASCIIEncoding.ASCII;
using (var reader = new System.IO.StreamReader(response.GetResponseStream(), encoding))
{
string responseText = reader.ReadToEnd();
}
}
catch(WebException ex)
{
HttpWebResponse xyz = ex.Response as HttpWebResponse;
var encoding = ASCIIEncoding.ASCII;
using (var reader = new System.IO.StreamReader(xyz.GetResponseStream(), encoding))
{
string responseText = reader.ReadToEnd();
}
}
Basically ProtocolError indicates that you have received the response but there is an error related to protocol, which you can observe, when you read the response content from exception. I have added catch to handle the exception and read ex.Response (which is HttpWebResponse) and could see that the API is asking for user-agent to be suppllied while making the call. I got to see the error as "{"message":"User-Agent header is required."}"
You can ignore the code inside the exception block, I used it only to see what is the actual response message, which contains actual error details
Note: I have boxed WebRequest to HttpWebRequest to have additional http protocol related properties and most importantly "UserAgent" property which is not available with the WebRequest class.

You need to Accept the certificarte, Google for access to a https webrequest.
Like this

How can i login to linkedin using HTTP POST Request with C#

I am working on a simple Windows Forms program that take a username and password from a "Textbox" then it show my linked-in name in a "Messagebox".
I want to accomplish the code with the using of "HttpWebRequest" or using any method to send my POST request to Linked-in then i can get the response and find my name to shown it in a "Messagebox".
I am familiar with creating a "GET" Request and also i made some "POST" Requests but in this case i didn't know how can i send my "txt_UserName.Text" and "txt_Password" with the POST Request and how can i receives the Response.
I tried to using Fiddler to capture POST request (=POST) from linkedin when i try to login but it captures more than 4 requests when i see the header of them it seem like a GET Request this is an example of one:
GET /nhome/?trk= HTTP/1.1
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
and all of them have a multiple cookies values.
This is my POST request code:
public void SubmitData()
{
try
{
string postData = "This is a test that posts this string to a Web server.";
byte[] byteArray = Encoding.UTF8.GetBytes(postData);
// Create a request using a URL that can receive a post.
WebRequest request = WebRequest.Create("http://www.linkedin.com");
// Set the Method property of the request to POST.
request.Method = "POST";
// Set the ContentLength property of the WebRequest.
request.ContentLength = byteArray.Length;
//Content Length
request.ContentLength = byteArray.Length;
// Get the request stream.
Stream dataStream = request.GetRequestStream();
// Write the data to the request stream.
dataStream.Write(byteArray, 0, byteArray.Length);
// Close the Stream object.
dataStream.Close();
// Get the response.
WebResponse response = request.GetResponse();
dataStream = response.GetResponseStream();
StreamReader sr = new StreamReader(dataStream);
MessageBox.Show(sr.ReadToEnd());
sr.Close();
dataStream.Close();
}
catch (Exception ex)
{
MessageBox.Show("Error: " + ex.Message);
}
}
Now the only thing i wish to know, how can i send my username and password as a values to login to linked-in?
Edit:
Below is my second try, it's ok, i can now send the User and Password in postData and i can store the Cookies and retrive it. but there are two issues:
1- how can i make sure that the login is accomplished and not failed
2- if the login is accomplished i want to know what is the second step to get my name from profile, is it made another request or what ?
private void button1_Click(object sender, EventArgs e)
{
PostMessage();
}
private void PostMessage()
{
try {
// POST Data and the POST uri
string postData = "isJsEnabled=true&source_app=&session_key=" + textBox1.Text + "&session_password=" + textBox2.Text + "&signin=Sign+In&session_redirect=";
string uri = "https://www.linkedin.com/uas/login-submit";
// Encoding the POST Data
byte[] byteArray = Encoding.UTF8.GetBytes(postData);
// Create the POST Request
HttpWebRequest WebReq = (HttpWebRequest)WebRequest.Create(uri);
//POST Parameters (Method and etc.)
WebReq.Method = "POST";
WebReq.ContentType = "application/x-www-form-urlencoded";
WebReq.ContentLength = byteArray.Length;
// Set the POST Request Cookies
var cookieContainer = new CookieContainer();
WebReq.CookieContainer = cookieContainer;
// Get the request stream.
Stream dataStream = WebReq.GetRequestStream();
// Write the data to the request stream.
dataStream.Write(byteArray, 0, byteArray.Length);
// Close the Stream object.
dataStream.Close();
// Get the response.
HttpWebResponse response = (HttpWebResponse)WebReq.GetResponse();
dataStream = response.GetResponseStream();
StreamReader sr = new StreamReader(dataStream);
//MessageBox.Show(sr.ReadToEnd());
sr.Close();
dataStream.Close();
if (response.StatusCode != HttpStatusCode.OK)
{
MessageBox.Show(" Error: " + response.StatusDescription);
response.Close();
}
foreach (Cookie cook in response.Cookies)
{
MessageBox.Show(cook.Name + " " + cook.Value);
}
}
catch (Exception ex)
{
MessageBox.Show("POST Message Error: " + ex.Message);
}
}

I used Fiddler while I was logging in and found a request to https://www.linkedin.com/uas/login-submit containing the username and password. Found it? Now, if you want to look at it completely from an HTTP Request perspective, you will have to figure out how to generate the other data in the post data/cookie header using the other requests and responses that your browser sent and received to and from the site before this particular request (the information should be there). I think this will lead you to what you need to do, but there's some work to be done!

You're going to need more than you think to log in there is good documentation on how to do this just here, you are going to need an auth token etc, This is because like other services, for example google, they are using oauth2 to secure applications etc.
oauth works by issuing tokens and refreshing tokens and there's a bit of a learning curve but its not especially difficult.
Essentially the following happens
You register your application with linked in and they give you a
client secret.
You pass this code to linked in in your application
and they will generate an auth screen saying that the application is
requesting permission.
you then approve this and it will give you an access token
You then log in with the access token (access tokens on linkedin are valid for 60 days, you must refresh them by this time).
On the plus side the linked in api is pretty straight forward and once authorised you will be able to get stuff pretty easily. All of this is detailed in the link provided in nice step by step stages.
By the way there is also a nuget package that gives you access to profile information.
Try Install-Package LinkedIn
I should point out that the nuget package above gives you a login provider to help authenticate if you don't want to roll your own.
Added after your comments below.
If all you want to do is know how to send a post request here's a generic bit of code that does just that:
string url = "www.foo.bar.com";
using (var webClient= new WebClient())
{
var data = new NameValueCollection();
data["username"] = "<yourusername>";
data["password"] = "<yourPassword>";
var response = webClient.UploadValues(url, "POST", data);
}
note: because its a web uri you should use POST in the method argument here.

The problem you up against is that Linkedin uses a redirect within the login session and is differcult to catch.
So somehow within the login session you need to code that it redirects to the https://www.linkedin.com/nhome/?trk= this provides the user page access.
I am also testing with this, however did not manage to figure this part out, normally
httpWebRequest.AllowAutoRedirect = true;
should do the trick but not in this case it does not work.
So if you find the solution let me know, if I find will post it also.

How can I avoid a "Bad Request - Invalid Hostname" error when making a REST call from a Compact Framework client?

I used this code from here to try to call a REST Controller method on a Web API server app from a Compact Framework client:
public static void SendXMLFile3(string uri, string data)
{
WebRequest request = WebRequest.Create (uri);
request.Method = "POST";
string postData = data;
byte[] byteArray = Encoding.UTF8.GetBytes (postData);
request.ContentType = "application/x-www-form-urlencoded";
request.ContentLength = byteArray.Length;
Stream dataStream = request.GetRequestStream ();
dataStream.Write (byteArray, 0, byteArray.Length);
dataStream.Close ();
WebResponse response = request.GetResponse ();
MessageBox.Show(((HttpWebResponse) response).StatusDescription);
dataStream = response.GetResponseStream ();
StreamReader reader = new StreamReader (dataStream);
string responseFromServer = reader.ReadToEnd();
MessageBox.Show(responseFromServer);
reader.Close ();
dataStream.Close ();
response.Close ();
}
...I had earlier tried this code, which I got from the book "Microsoft .NET Compact Framework":
public static void SendXMLFile2(string uri, string data)
{
WebRequest req = WebRequest.Create(uri);
req.Method = "Post";
req.ContentType = "text/plain; charset=utf-8";
byte[] encodedBytes = Encoding.UTF8.GetBytes(data);
req.ContentLength = encodedBytes.Length;
Stream requestStream = req.GetRequestStream();
requestStream.Write(encodedBytes, 0, encodedBytes.Length);
requestStream.Close();
WebResponse result = req.GetResponse();
MessageBox.Show(result.ToString());
}
...but I get "400 - Bad Request" with the new (as well as the old) code.
My initial attempt also does not work, with the same result (400):
public static string SendXMLFile(string xmlFilepath, string uri, int timeout)
{
HttpWebRequest myHttpWebRequest=(HttpWebRequest)WebRequest.Create(uri);
myHttpWebRequest.AllowWriteStreamBuffering=false;
string postData = "<Command><DSD><line_id>1</line_id><invoice_no>david_dsd</invoice_no>. . .</DSD></Command>"; // TODO: if this works, replace it with the real data
myHttpWebRequest.Method="POST";
UTF8Encoding encodedData = new UTF8Encoding();
byte[] byteArray=encodedData.GetBytes(postData);
myHttpWebRequest.ContentType = "application/xml";
myHttpWebRequest.ContentLength=byteArray.Length;
Stream newStream=myHttpWebRequest.GetRequestStream();
newStream.Write(byteArray,0,byteArray.Length);
newStream.Close();
HttpWebResponse myHttpWebResponse=(HttpWebResponse)myHttpWebRequest.GetResponse();
return myHttpWebResponse.StatusDescription;
}
There is much more about the plethora of variations I have tried here, where I have reached my length-of-post limit.
UPDATE
Note that the Server code doesn't know/care that the file is XML:
[HttpPost]
[Route("api/inventory/sendXML/{userId}/{pwd}/{filename}")]
public async Task SendInventoryXML(String userId, String pwd, String fileName)
{
Task task = Request.Content.ReadAsStreamAsync().ContinueWith(t =>
{
var stream = t.Result;
using (FileStream fileStream = File.Create(String.Format(#"C:\HDP\{0}.xml", fileName), (int)stream.Length))
{
byte[] bytesInStream = new byte[stream.Length];
stream.Read(bytesInStream, 0, (int)bytesInStream.Length);
fileStream.Write(bytesInStream, 0, bytesInStream.Length);
}
});
}
UPDATE 2
I tried Charles to see if it would pick up the local HTTP traffic, but it is also deaf to such (like Fiddler, without special ministrations, anyway). This is what Charles looks like after getting the "400 - Bad Request" error:
UPDATE 3
I found this suggestion somewhere to get Fiddler to show local HTTP traffic:
Tools--> Fiddler Options. Choose Connections tab. Check the 'USe PAC Script' option.
...but it didn't work - I still see no HTTP traffic when getting the "400 (Bad Request)" message.
UPDATE 4
I am now seeing "400 (Bad Request)" in Fiddler 2, too; to get it, I enter any of the following in Postman (don't see this in Fiddler when calling from CE/CF/handheld app):
http://SHANNON2:21608/api/inventory/sendXML/su/su/blablee // Hostname
http://SHANNON2.:21608/api/inventory/sendXML/su/su/blablee // Hostname with Fiddler-fooler appended "."
http://192.168.125.50:21608/api/inventory/sendXML/su/su/blablee // IP Address
(Fiddler does not capture anything if I replace the hostname or IP Address with "localhost")
Note: For these URLs in Postman, I have "Post" (as opposed to GET, etc.) selected, and an XML file attached.
Inspectors.Headers in Fiddler shows:
POST /api/inventory/sendXML/su/su/blablee HTTP/1.1
Although I consider this a minor debugging victory, I still don't see why I'm getting the "400" error.
Fiddler tells me, in the Inspectors.WebView pane:
Bad Request - Invalid Hostname
--------------------------------------------------------------------------------
HTTP Error 400. The request hostname is invalid.
How can that be? When I run it from Postman, I hit the breakpoint in the server - if the hostname is invalid, why is it being reached?
UPDATE 5
Testing the call from Fiddler Composer and Postman, the only way I can reach the breakpoint in the server code is by using "localhost" - replacing that with the PC's IPAddress (192.168.125.50) or HostName (SHANNON2) does not reach the breakpoint. While "interesting," calling "localhost" from the handheld device is obviously not an option.
UPDATE 6
Related new question here.
UPDATE 7
The crux of the biscuit was adding at the command prompt either this:
netsh http add urlacl url=http://shannon2:80/ user=everyone
...or this:
netsh http add urlacl url=http://shannon2:8080/ user=everyone
See Update 5 here for more details

Adding my observations, if you are facing the issue Bad Request - Invalid Hostname while calling the API from Postman. Something like this.
Consider adding the Host in Headers, it will work.
Updated after someone is not able to view the image: If the images are not loading, then basically this you have to do:
Basically, you have to add Content-Length and Host. Postman auto calculates when the request is sent. These can be enabled in postman by unhiding auto-generated headers in Postman. or you can set by your own.

The crux of the biscuit was adding at the command prompt either this:
netsh http add urlacl url=http://shannon2:80/ user=everyone
...or this:
netsh http add urlacl url=http://shannon2:8080/ user=everyone
See Update 5 here for more details

Posting to a REST webservice from .NET?

I was trying to hit a web service using the instructions here:
http://help.seeclickfix.com/kb/api/creating-an-issue
I came up with the code below:
string paramContent = "api_key=afs684eas3ef86saef78s68aef68sae&issue[summary]=abeTest&issue[lat]=39.26252982783172&issue[lng]=-121.01738691329956&issue[address]=111 Abe St., Nevada City, CA";
byte[] paramBytes = Encoding.UTF8.GetBytes(paramContent);
HttpWebRequest req = (HttpWebRequest)WebRequest.Create("http://seeclickfix.com/api/issues.xml");
req.Method = "POST";
req.ContentLength = paramBytes.Length;
//req.ContentType = "application/x-www-form-urlencoded";
using (Stream reqStream = req.GetRequestStream())
{
reqStream.Write(paramBytes, 0, paramBytes.Length);
}
using (HttpWebResponse resp = (HttpWebResponse)req.GetResponse()) //HERE!
{
if (resp.StatusCode != HttpStatusCode.OK)
{
string message = String.Format("POST failed. Received HTTP {0}", resp.StatusCode);
throw new ApplicationException(message);
}
StreamReader sr = new StreamReader(resp.GetResponseStream());
string response = sr.ReadToEnd();
Console.WriteLine(response + System.Environment.NewLine);
}
But at the line with the HERE! comment it throws the error:
The remote server returned an error: (500) Internal Server Error.
Can anyone see any problems with the way I am trying to implement this?

The 500 error you are getting indicates a problem on the server, not necessarily a problem with your code. You are successfully sending a request and receiving a response.
The problem could be a bug in the server, or a problem with the content of your request that the server can't handle. (Either way the server is failing to provide a valid error message like their documentation suggests it would)
You should start by making sure the content of your request is valid. See the example on the seeclickfix url you posted. Try directly posting with curl like they show, but use the content of your own message like so:
curl -v -d 'api_key=afs684eas3ef86saef78s68aef68sae&issue[summary]=abeTest&issue[lat]=39.26252982783172&issue[lng]=-121.01738691329956&issue[address]=111 Abe St., Nevada City, CA' http://seeclickfix.com/api/issues.xml
I expect you'll still get a 500 error (I just tried it and I got a 500 error).
Bottom line, it looks like their api is broken, not your logic.

You didn't do anything wrong. I tried making the request using Fiddler and it returned the same 500 status code.
If there was something wrong with the data you passed then they should have returned a 4XX response code.

POST Json String to Remote PHP Script using Json.NET

I am encountering an unusually strange behavior when POSTing a Json string to a PHP webserver. I use the JsonTextWriter object to create the Json string. I then send the Json string as a POST request. Please see comments. The HTML response in the code is returning the correct output, but when viewed in a browser, the web page displays either NULL or array(0) { }.
private void HttpPost(string uri, string parameters)
{
WebRequest webRequest = WebRequest.Create(uri);
webRequest.ContentType = "application/x-www-form-urlencoded"; // <- Should this be "application/json" ?
webRequest.Method = "POST";
byte[] bytes = Encoding.UTF8.GetBytes(parameters);
string byteString = Encoding.UTF8.GetString(bytes);
Stream os = null;
try
{ // Send the Post Data
webRequest.ContentLength = bytes.Length;
os = webRequest.GetRequestStream();
os.Write(bytes, 0, bytes.Length);
Console.WriteLine(String.Format(#"{0}", byteString)); // <- This matches the Json object
}
catch (WebException ex)
{ //Handle Error }
try
{ // Get the response
WebResponse webResponse = webRequest.GetResponse();
if (webResponse == null) { return null; }
StreamReader sr = new StreamReader(webResponse.GetResponseStream());
Console.WriteLine(sr.ReadToEnd().Trim()); // <- Server returns string response (full HTML page)
}
catch (WebException ex)
{ //Handle Error }
}
Relevant PHP code on the server:
$json = json_encode($_POST); # Not 'standard way'
var_dump(json_decode($json));
Any suggestions would be greatly appreciated.
Thanks

Try using "application/json" as the content type. Also, check the request logs or maybe do a port 80 trace if you can to view what's being sent to the server in the request body.
You can also narrow the scope of the problem -- is it the C# code or the PHP code that's bad -- by writing a quick JQuery ajax function that sends some JSON to the PHP server. This isolation of the PHP code from the C# code will tell you if the PHP is at least working correctly. If it is, then the problem is in the C# code.