HttpResponseMessage returns 403 in .NET

Question

I have a async method which make a HttpClient call repeatedly in .Net. I simulate my code as a small console app below:

    private static HttpClient req { get; set; } = new HttpClient();

    static async Task Main(string[] args)
    {
        Console.WriteLine("Please press enter to start healthCheck");
        Console.ReadLine();

        healthCheck();

        Console.ReadLine();
    }

    private static async Task healthCheck()
    {
        while (true)
        {
            req.DefaultRequestHeaders.Add("apikey", "myPassword");

            string strUrl = "http://myUrl";

            HttpResponseMessage hrm = await req.GetAsync(strUrl);

            Console.WriteLine("=> statusCode:" + (int)hrm.StatusCode);

            await Task.Delay(5000);
        }
    }

The output is:

The problem is when I use Postman or write this code with python as below, every time it responded 200 instead of 403.

import requests as req
import time as t

url = "http://adpsms.adpdigital.com/report/?date=2021-08-30"
customHeader = {"apikey": "sssrjdIiGisbViKA"}

i = 10

while (i > 0):
    response = req.get(url, headers = customHeader)

    print("statusCode: " + str(response.status_code))

    i -= 1
    t.sleep(5)

I supposed it is a server error but when I responded 200 every time with python I understand it would be a problem with my code or something client based.

Since my project is based on .NET I want to make it work on it. Any suggestion would be appreciated.

Answer 1

On every iteration of your loop, you are adding DefaultRequestHeaders. It means that they will be added again and again on each iteration of your cycle to the global instance of HttpClient

According to the official docs these headers will be sent with each request. For your particular task you might add them only once(that's why the name contains prefix default.)

So if you slightly rewrite your code like this:

private static HttpClient req { get; set; } = new HttpClient();

    static async Task Main(string[] args)
    {
        Console.WriteLine("Please press enter to start healthCheck");
        Console.ReadLine();
        AddDefaultHeaders();
        healthCheck();
    
        Console.ReadLine();
    }
    
    private static void AddDefaultHeaders()
    {
        req.DefaultRequestHeaders.Add("apiKey", "myPassword");
    }

    private static async Task healthCheck()
    {
        while (true)
        {
            string strUrl = "http://myUrl";
    
            HttpResponseMessage hrm = await req.GetAsync(strUrl);
    
            Console.WriteLine("=> statusCode:" + (int)hrm.StatusCode);
    
            await Task.Delay(5000);
        }
    }

It should works fine.