How do I handle HTTP redirects with HttpClient (C#)?

When using HttpClient in C#, HTTP redirects can either be handled automatically or manually, depending on the configuration of the HttpClientHandler used by the HttpClient instance.

By default, HttpClient will automatically follow HTTP redirection responses (like 301, 302, 303, or 307) unless the redirection count exceeds the limit (which by default is set to 50).

Handling Redirects Automatically

Here's an example of how to use HttpClient with default settings that automatically handle redirects:

using System;
using System.Net.Http;
using System.Threading.Tasks;

class Program
{
    static async Task Main(string[] args)
    {
        using (var httpClient = new HttpClient())
        {
            // Send a GET request
            HttpResponseMessage response = await httpClient.GetAsync("http://example.com");

            // The response will be the final response after following any redirects
            if (response.IsSuccessStatusCode)
            {
                string content = await response.Content.ReadAsStringAsync();
                Console.WriteLine(content);
            }
        }
    }
}

Custom Redirect Handling

If you want to control the redirect behavior, you can configure the HttpClientHandler as follows:

using System;
using System.Net.Http;
using System.Threading.Tasks;

class Program
{
    static async Task Main(string[] args)
    {
        // Create an HttpClientHandler and configure it to handle redirects manually
        var handler = new HttpClientHandler
        {
            AllowAutoRedirect = false // Disable automatic redirection
        };

        using (var httpClient = new HttpClient(handler))
        {
            // Send a GET request
            HttpResponseMessage response = await httpClient.GetAsync("http://example.com");

            // Manually check if the response is a redirection
            if (response.StatusCode == System.Net.HttpStatusCode.Redirect ||
                response.StatusCode == System.Net.HttpStatusCode.MovedPermanently ||
                response.StatusCode == System.Net.HttpStatusCode.Found ||
                response.StatusCode == System.Net.HttpStatusCode.SeeOther ||
                response.StatusCode == System.Net.HttpStatusCode.TemporaryRedirect)
            {
                // Get the URL to redirect to
                Uri redirectUrl = response.Headers.Location;

                // Decide if you want to follow the redirect and make a new request
                HttpResponseMessage redirectResponse = await httpClient.GetAsync(redirectUrl);
                if (redirectResponse.IsSuccessStatusCode)
                {
                    string content = await redirectResponse.Content.ReadAsStringAsync();
                    Console.WriteLine(content);
                }
            }
        }
    }
}

In the above code, AllowAutoRedirect is set to false, which means that HttpClient will not follow redirects automatically. You can then check the response status code to see if it's a redirect and manually issue a new request to the URL specified in the Location header.

Remember that manually handling redirects gives you more control to inspect and modify the request before following the redirect, but it also means you need to handle things like redirect loops and maximum redirect counts yourself.