Develop Reference

GET request works on Postman but fail with RestSharp

I know that similar questions have been already posted in the past but I read a lot on the subject and still couldn't find an answer to my problem.
I have a GET request that works fine on Postman:
I translated it with the Code tool in C# - RestSharp and tested it with my plugin but somehow I always get the same error:
My C# - RestSharp code (It's the one I get with the Postman translator):
var client = new RestClient("https://..........."); //my url
client.Timeout = -1;
var request = new RestRequest(Method.GET);
request.AddHeader("Cookie", ".........."); //my cookie
IRestResponse response = client.Execute(request);
I tried adding all the headers visible in the Headers section:
request.AddHeader("User-Agent", "PostmanRuntime/7.29.0");
request.AddHeader("Accept", "*/*");
request.AddHeader("Accept-Encoding", "gzip, deflate, br");
request.AddHeader("Connection", "keep-alive");
without result. The Authorization type is No Auth. Any idea?
Maybe it has something to do with the fact that the response body in Postman is a plain text? The other requests I send that have a JSON response works perfectly fine.
Thank you for your help!

Use request.AddCookie(cookiename, cookievalue);

Flask 400 Bad Request when sent from C# App, but 200 from Postman?

I am posting the following JSON to my Flask server:
{"comment": "astute observation", "ua": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/95.0.4638.69 Safari/537.36", "cookie": "ua=f8256d37159e3faf28ae61a6406601c3; platform=pc; bs=bxa7ziiq07dufk31prvoo0mbfm44sayh; ss=994139249854417186; il=v1qyca8PU7X6jSwgiqceXsySwWB60HnCjSJ1HjNmsSxRUxNjQzNjA3OTEycUVTTFoxWUpSZDFTZ3kwclIzenBHa19FbnlmMTlIN0hZeHNDQ1FOLQ..; expiredEnterModalShown=1", "parent": "860245961"}
When sent from Postman, the request works flawlessly. However, when sent from my C# app, like so, the server returns a 400 Bad Request error code.
var data = $"{{\"comment\": \"{text}\", \"ua\": \"{userAgent}\", \"cookie\": \"{cookie}\", \"parent\": \"{parent}\"}}";
var url = "http://127.0.0.1:5000/";
var request = HttpWebRequest.CreateHttp(url);
request.Method = "POST";
request.ContentType = "application/json";
await using var sw = new StreamWriter(request.GetRequestStream());
await sw.WriteAsync(data);
var response = await request.GetResponseAsync();
To make sure that the JSON is properly formatted, I set a breakpoint and inspected the "data" variable. I copied/pasted that value into Postman, set the Content-Type to application/json, and the request succeeds from there, but fails from my C# application.
Server code:
from flask import Flask, request
app = Flask(__name__)
#app.route('/', methods=['GET', 'POST'])
def process():
print(request.json)
return 'Hello'
app.run(debug=True)
Edit: After posting this, I realized I wasn't sending a user agent from my C# app. I tried adding one and the server still responds with a 400 Bad Request error.
Edit 2: I tried simplifying the data variable for testing purposes. var data = "{\"msg\": \"david\"}"; and setting request.ContentLength = data.Length, still having the same problem. Really strange.

Very odd, but this solved the problem. Using the StreamWriter class was causing the issue. Doing this instead results in a 200 OK response finally.
using var stream = request.GetRequestStream();
await stream.WriteAsync(Encoding.UTF8.GetBytes(data));

Call works in Postman but not in C#

I am trying to make a call to below URL and it works just fine in Browser (Chrome) and also in Postman, but for some reason, it doesn't work in C#.
Working in browser:
http://AJWKBLWT47VR26QWPNFCPJLXC6217F6F#presta.craftingcrow.com/api/categories
Working in Postman:
http://AJWKBLWT47VR26QWPNFCPJLXC6217F6F#presta.craftingcrow.com/api/categories
Not working in C# (RestSharp):
var client = new RestClient("http://AJWKBLWT47VR26QWPNFCPJLXC6217F6F#presta.craftingcrow.com/api/categories");
var request = new RestRequest(Method.GET);
request.AddHeader("cache-control", "no-cache");
request.AddHeader("User-Agent", #"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.106 Safari/537.36");
IRestResponse response = client.Execute(request);
Response:
401 Unauthorized
P.S. If I remove User-Agent it still doesn't work. Why am I doing wrong here?

Go into postman and, after you submit the request, check the Headers tab for anything that may have been added in the "temporary headers" section if you haven't specified anything in the Authorization tab.
In this example, I haven't called out an Authorization header but Postman is supplying one anyway:
Then add the missing relevant header(s) into your code. I like to click the "Code" button to the far right of the request. It gives you a dropdown so that you can choose pre-generated code in your desired language. This will most likely give you a reproducible example.

Thanks to Joshua & Vhoang!
It's working after I changed code to below:
var client = new RestClient("http://presta.craftingcrow.com/api/categories");
var request = new RestRequest(Method.GET);
request.AddHeader("cache-control", "no-cache");
request.AddHeader("Authorization", "Basic " + Convert.ToBase64String(Encoding.Default.GetBytes("AJWKBLWT47VR26QWPNFCPJLXC6217F6F:"));
IRestResponse response = client.Execute(request);
There was no need to add user-agent or include key in the hostname (URL)

RestClient constructor accepts URI that doesn't include userinfo
userinfo host port
┌──┴───┐ ┌──────┴──────┐ ┌┴┐
https://john.doe#www.example.com:123/forum/questions/?tag=networking&order=newest#top
└─┬─┘ └───────────┬──────────────┘└───────┬───────┘ └───────────┬─────────────┘ └┬┘
scheme authority path query fragment
See: https://en.wikipedia.org/wiki/Uniform_Resource_Identifier
In order to make it work with RestSharp, we'll need to do a little bit of extra work here:
// Old:
// var client = new RestClient("http://AJWKBLWT47VR26QWPNFCPJLXC6217F6F#presta.craftingcrow.com/api/categories");
// New:
var client = new RestClient("http://presta.craftingcrow.com/api/categories")
{
Authenticator = new HttpBasicAuthenticator("AJWKBLWT47VR26QWPNFCPJLXC6217F6F", "")
};

Why does my HttpWebRequest return a 503?

So i am just getting to learn HttpWebRequests and it's functions.
I've gotten to the point where I want to learn how to capture cookies in a CookieContainer and parse through them.
The issue is that some websites return a 503 error and I am not sure.
One of the websites will be used in this example.
From what Iäve read online a 503 error is this.
The HyperText Transfer Protocol (HTTP) 503 Service Unavailable server
error response code indicates that the server is not ready to handle
the request.
Common causes are a server that is down for maintenance or that is
overloaded. This response should be used for temporary conditions and
the Retry-After HTTP header should, if possible, contain the estimated
time for the recovery of the service.
Which doesnt seem to fit in at all since the website is up and running.
Why is my request returning a 503 status code and what should I do to resolve this issue in a propper manner?
static void Main(string[] args)
{
//1. Create a HTTP REQUEST
//Build the request
Uri site = new Uri("https://ucp.nordvpn.com/login/");
//Inizializing a new instance of the HttpWebRequest and casting it as a WebRequest
//And calling the Create function and using our site as a paramter which the Create function takes.
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(site);
//Inizialize a new instance of the CookieContainer
CookieContainer cookies = new CookieContainer();
//The request has a CookieContainer, which is null by default, so we are just assinging the newly inizialized instance
//of our CookieContainer to our requests CookieContainer
request.CookieContainer = cookies;
//Print out the number of cookies before the response (of course it will be blank)
Console.WriteLine(cookies.GetCookieHeader(site));
//Get the response and print out the cookies again
using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
{
Console.WriteLine(cookies.GetCookieHeader(site));
}
Console.ReadKey();
}

The URL that you are trying to get to appears to be protected by CloudFlare. You can't use the basic HttpWebRequest for that type of request without some additional work. While I haven't tried this, it may be an option for you to get around that protection:
CloudFlareUtilities

The url you are trying to access is using cloud hosting which use many security measurement including which browser are accessing the site
for that to work you need to change the userAgent property of HttpWebRequest
request.UserAgent = "Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:59.0) Gecko/20100101 Firefox/59.0";

Accessing ASP.NET_SessionId on HttpWebResponse C#

I'm trying to get ASP.NET_SessionId from a HttpWebResponse but it seems that no such data comes on the response.
Basically I'm trying to simulate some steps over some pages, where authentication is required. The problem is not in the authentication, my problem is to get ASP.NET_SessionId after the authentication so I can use it in my future requests/steps.
From Chrome on developer tools > network, I can see the ASP.NET_SessionId on the headers, but it does not come in my HttpWebResponse. Any ideia why this is happening?
There is my code:
var httpWebRequest = (HttpWebRequest) WebRequest.Create(url);
httpWebRequest.UserAgent = "Mozilla/5.0 (Windows NT 10.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/40.0.2214.93 Safari/537.36"; httpWebRequest.Method = "POST";
httpWebRequest.ContentType = "application/x-www-form-urlencoded";
httpWebRequest.ContentLength = 0;
var httpWebResponse = (HttpWebResponse) httpWebRequest.GetResponse();
After my request I should see a ASP.NET_SessionId header Set-Cookie, but no luck. Any ideia?
I've seen some people say that
httpWebResponse.Headers["ASP.NET_SessionId"]
or
httpWebResponse.Headers["SESSION_ID"]
should work but no, no session id header is set nor any Cookie.

After many research, the answer was here
Basically we have to keep the same CookieContainer object reference across all requests. I was extracting some Set-Cookie from the responses and adding them into my requests, but now I don't need to do anything, CookieContainer manages all of it transparently.
Set-Cookie from responses are set on CookieContainer of your request. It's the way they found to resolve possible security issues, so don't lose more time and just keep a reference to your CookieContainer because you will not be able to access session id (and you don't need it).
There's the example of my code now.
var cookieContainer = new CookieContainer();
var httpWebRequest1 = (HttpWebRequest) WebRequest.Create(url);
httpWebRequest1.CookieContainer = cookieContainer;
// do the request and some logic
var httpWebRequest2 = (HttpWebRequest) WebRequest.Create(anotherUrl);
httpWebRequest2.CookieContainer = cookieContainer; // same cookieContainer reference
Everything is working great now, hope it helps someone.