Develop Reference

HttpClient decoding my encoded URI causes request to fail

HttpClient seems to not respect encoded strings.
var id = Uri.EscapeDataString("\"MyId\"");
var uri = new Uri($#"https://www.example.com/{id}").AbsoluteUri;
var req = new HttpRequestMessage(HttpMethod.Post, uri);
My uri object contains https://www.example.com/%22MyId%22 which is correct.
Inspecting req.RequestUri shows the correct value for every property except for LocalPath, everything else seems to have the correct %22 encoded quote.
I then send the request:
await httpClient.SendAsync(req)
and it makes a request to https://www.example.com/"MyId" (no longer encoded?) and the request fails.
uri.UserEscaped shows false after creating. I tried to escape the entire URI using Uri.EscapeUriString, but that function is deprecated and suggests using Uri.EscapeDataString for the query (which I'm already doing).
I followed the solution from the GitHub issue in this question, however it did not fix my issue (using AbsoluteUri).
This question is incorrect as it is not just the ToString() method, the actual request includes the decoded values.
This question is just a dead link.
How can I actually send my request with the encoded %22 quote values?

Don't do that Uri.EscapeDataString, just include the id as-is in the Uri.
var id = "\"MyId\"";
var uri = new Uri($#"https://www.example.com/{id}").AbsoluteUri;
var req = new HttpRequestMessage(HttpMethod.Post, uri);
Fiddler shows below request was made.
POST https://www.example.com/%22MyId%22

you can use them (namespace System.Web)
HttpUtility.UrlDecode("")
HttpUtility.UrlEncode("")

ADFS v4.0 and /userinfo endpoint giving 405

Integrating older ASP.NET server-side application into ADFS for authentication, which means I pretty much had to write everything from scratch. have everything working (/authorize, /token) up until the /userinfo call.
My code, in a nutshell -
HttpClient client = new HttpClient();
var req = new HttpRequestMessage {
RequestUri = new Url("https://<server_ip>/adfs/oauth2/userinfo"),
Method = HttpMethod.Get,
};
req.Headers.Authorization = new AuthenticationHeaderValue("Bearer", token.AccessToken);
req.Headers.UserAgent.Clear();
req.Headers.UserAgent.Add(new ProductInfoHeaderValue("OldApp", "11.3.0"));
var result = await client.SendAsync(req);
The result is a HTTP error 405 - Method Not Allowed. Doing searches online, I see this as a common issue when the trailing "/" is left off the url, but I get the same result with a trailing slash.
After poking around, there are a lot of examples that use newer libraries and such that I can't use, sadly. None mention usage of the /userinfo, and I'm thinking that the issue isn't necessarily in how I'm calling the URL, but configuration of the 'Application Group' in ADFS.

Okay - I found the issue, and will document it here in case others come across the same thing..
While I am not sure why /userinfo is giving a 405 - the URL I was using is wrong, despite it being listed in the Endpoints folder. There shouldn't be any "oauth2" in the URL. The correct code (and URL) is:
var req = new HttpRequestMessage {
RequestUri = new Url("https://<server_ip>/adfs/userinfo"),
Method = HttpMethod.Get,
};
req.Headers.Authorization = new AuthenticationHeaderValue("Bearer", token.AccessToken);
req.Headers.UserAgent.Clear();
req.Headers.UserAgent.Add(new ProductInfoHeaderValue("OldApp", "11.3.0"));
var result = await client.SendAsync(req);
Also something to keep in mind - this has been stated elsewhere, but not as clearly as here, I hope:
The /userinfo will ONLY give you the NameIdentifier ("sub") claim. (As far as I can see.) No matter what scope you pass it. You will get all your information (that should normally be in the /userinfo call) in the "id_token" parameter from you /token call, encoded as JWT.

Personally I was led to do the same thing as you, the only solution was to download the ADAL library (You will find the link below) and debug the code in order to re-produce the same HTTP stream from ADAL.
You can create a new project so that you can integrate ADAL, for debugging or else intercepting the HTTP stream
Link ADAL

How do I send a post request to telegram API from C#?

I have my telegram application with app's api_id and app's api_hash.
I used TLSharp library for implementing my own things. But now I need to use this https://core.telegram.org/method/auth.checkPhone telegram api method, but it's not implemented in TLSharp library!
I don't mind doing it all manually, but I don't know how!
I know how you send post requests in C#, example:
var response = await client.PostAsync("http://www.example.com/index", content);
but in this specific case I don't. Because I don't know:
1) what link should I use for sending post requests? I couldn't find it on the telegram's website.
2) what content should I pass there? Should it be just "(auth.checkPhone "+380666454343")" or maybe the whole "(auth.checkPhone "+380666454343")=(auth.checkedPhonephone_registered:(boolFalse)phone_invited:(boolFalse))" ?
So, How do I sent this post request to the telegram api? (NOT telegram bot api!)

Try to use System.Net.Http like in this example (auth request to the server):
var user = new { login = "your login", password = "your pass" };
string json = JsonConvert.SerializeObject(user);
HttpContent content = new StringContent(json, Encoding.UTF8, "application/json");
HttpClient client = new HttpClient();
HttpRequestMessage request = new HttpRequestMessage();
request.RequestUri = new Uri("server route link"); // can be like https://a100.technovik.ru:1000/api/auth/authenticate
request.Method = HttpMethod.Post;
request.Content = content;
HttpResponseMessage response = await client.SendAsync(request);
responseText.Text = await response.Content.ReadAsStringAsync();

I think based on a brief look, that it would be more along the lines of your second example, e.g.:
var phonenumber = "0123456789";
var content =
$#"(auth.checkPhone ""{phonenumber}"")"+
"=(auth.checkedPhone phone_registered: (boolFalse) phone_invited:(boolFalse))";
var result = DoHttpPost("http://some.example.com/api/etc", content);
(note: I've not listed the actual mechanics of an HTTP Request here, as that is covered in plenty of detail elsewhere - not least in the other current answer supplied to you; DoHttpPost() is not a real method and exists here only as a placeholder for this process)
And since the payload of this appears to indicate the exact function and parameters required, that you'd just send it to the base api endpoint you use for everything, but I can't say for sure...
I do note they do appear to have links to source code for various apps on the site though, so perhaps you'd be better off looking there?

How to specify message body in a WebClient?

In the console, I follow up a call the site I'm on is is making and I can see the address (some.site.com/gettoken), message header and something that FF calls Message Body. It's in the latter that I can see the credentials that I've entered on the site that are being sent.
So, I've got the URL and the message body. Then, I've tried to implement the behavior using C# for my Azure service layer like so.
String url = #"https://some.site.com/gettoken";
String credentials = "username=super&password=secret";
using (WebClient client = new WebClient())
{
String output = client.UploadString(url, credentials);
result = output;
}
However, I get error 400 - bad result. What did I miss?
I've googled for some stuff but the only remotely relevant hits are talking about the upload methods, which I've used. Am I barking up the wrong tree entirely or just missing something tiny? Some people seem to get it to work but they're not tokenizing around. And I'm not certain enough to determine whether it's of relevance or not.

So, as a summary of what has been discussed in the comments: you can use the more modern HttpClient instead.
Note that this is the System.Net.Http.HttpClient and not Windows.Web.Http.HttpClient.
An example implementation could look like this:
public async Task<string> SendCredentials()
{
string url = #"https://some.site.com/gettoken";
string credentials = "username=super&password=secret";
using(var client = new HttpClient())
{
var response = await client.PostAsync(url, new StringContent(credentials));
return await response.Content.ReadAsStringAsync();
}
}
You might also be interested in System.Net.Http.FormUrlEncodedContent which allows you to pass in the parameters and their values so you don't have to construct the credentials value yourself.
More information on async/await.

WebRequest: Query string data vs x-www-form-urlencoded content

I am trying to call Google's OAuth2 authentication service as per these instructions: https://developers.google.com/accounts/docs/OAuth2ForDevices
I put all of the required parameters into the query string and sent the request. This worked for the "Obtaining a user code" section but not for the "Obtaining Access and Refresh Tokens" section.
After much playing around and getting 400 Bad Request errors, I found that, instead of putting the data in the query string, you can create a request with a FormUrlEncodedContent and send the data through as content with application\x-www-form-urlencoded Content-Type.
Here is the code before:
var requestMessage = new HttpRequestMessage();
requestMessage.Method = "POST";
requestMessage.RequestUri = new Uri(fullUrl);
Where fullUrl is something like:
https://accounts.google.com/o/oauth2/device/code?client_id=812741506391-h38jh0j4fv0ce1krdkiq0hfvt6n5amrf.apps.googleusercontent.com&scope=https%3A%2F%2Fwww.googleapis.com%2Fauth%2Fuserinfo.email%20https%3A%2F%2Fwww.googleapis.com%2Fauth%2Fuserinfo.profile
And the new code is:
var requestMessage = new HttpRequestMessage();
requestMessage.Method = "POST";
requestMessage.RequestUri = new Uri(url);
requestMessage.Content = new FormUrlEncodedContent(CreateDictionary(queryStringNames, queryStringValues));
Where url is:
https://accounts.google.com/o/oauth2/device/code
and queryStringNames and queryStringValues are string arrays of the names and values of the required parameters.
What is the difference between these two methods? Is it safe to assume that all POST calls can use the URL Encoded Content requests instead of putting the data in the query string?

In general, POST requests do not need query string but it is still subjected to Server's logic implementation. In case of OAuth which is quite known standard and they do follow good practice, it is safe to use form encoded data unless mentioned explicitly in API to send Parameter as query string.
Query String & Post data are two different set of parameters. If server is expecting Query string then you must send query string only. It all depends on how server side logic is implemented. You can not use them alternatively. Most API documentation specify clearly what are they expecting.