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Last active March 9, 2025 22:07
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A Simple HTTP server in C#
// Filename: HttpServer.cs
// Author: Benjamin N. Summerton <define-private-public>
// License: Unlicense (http://unlicense.org/)
using System;
using System.IO;
using System.Text;
using System.Net;
using System.Threading.Tasks;
namespace HttpListenerExample
{
class HttpServer
{
public static HttpListener listener;
public static string url = "http://localhost:8000/";
public static int pageViews = 0;
public static int requestCount = 0;
public static string pageData =
"<!DOCTYPE>" +
"<html>" +
" <head>" +
" <title>HttpListener Example</title>" +
" </head>" +
" <body>" +
" <p>Page Views: {0}</p>" +
" <form method=\"post\" action=\"shutdown\">" +
" <input type=\"submit\" value=\"Shutdown\" {1}>" +
" </form>" +
" </body>" +
"</html>";
public static async Task HandleIncomingConnections()
{
bool runServer = true;
// While a user hasn't visited the `shutdown` url, keep on handling requests
while (runServer)
{
// Will wait here until we hear from a connection
HttpListenerContext ctx = await listener.GetContextAsync();
// Peel out the requests and response objects
HttpListenerRequest req = ctx.Request;
HttpListenerResponse resp = ctx.Response;
// Print out some info about the request
Console.WriteLine("Request #: {0}", ++requestCount);
Console.WriteLine(req.Url.ToString());
Console.WriteLine(req.HttpMethod);
Console.WriteLine(req.UserHostName);
Console.WriteLine(req.UserAgent);
Console.WriteLine();
// If `shutdown` url requested w/ POST, then shutdown the server after serving the page
if ((req.HttpMethod == "POST") && (req.Url.AbsolutePath == "/shutdown"))
{
Console.WriteLine("Shutdown requested");
runServer = false;
}
// Make sure we don't increment the page views counter if `favicon.ico` is requested
if (req.Url.AbsolutePath != "/favicon.ico")
pageViews += 1;
// Write the response info
string disableSubmit = !runServer ? "disabled" : "";
byte[] data = Encoding.UTF8.GetBytes(String.Format(pageData, pageViews, disableSubmit));
resp.ContentType = "text/html";
resp.ContentEncoding = Encoding.UTF8;
resp.ContentLength64 = data.LongLength;
// Write out to the response stream (asynchronously), then close it
await resp.OutputStream.WriteAsync(data, 0, data.Length);
resp.Close();
}
}
public static void Main(string[] args)
{
// Create a Http server and start listening for incoming connections
listener = new HttpListener();
listener.Prefixes.Add(url);
listener.Start();
Console.WriteLine("Listening for connections on {0}", url);
// Handle requests
Task listenTask = HandleIncomingConnections();
listenTask.GetAwaiter().GetResult();
// Close the listener
listener.Close();
}
}
}
@leolamarra
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I am experimenting with this, but can I somehow display the real time visits count? Now I have to manually refresh the page and this can be really frustrating sometimes

@define-private-public
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Author

@CoderLel

For that, you'd need to add in some AJAX stuff ( https://en.wikipedia.org/wiki/Ajax_(programming) ) stuff.

@jmikepaz
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How enabled cors ? Access-Control-Allow-Origin", "*"

@gtato
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gtato commented Nov 26, 2021

used this for a demo.. thanks man :)

@Develeone
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Develeone commented Apr 10, 2022

Catch a crutch.

Little piece'o'code to keep things going in local network from other devices.
You need to open a certain port in Windows Firewall.
We don't gonna do it several times, cause it makes duplicate entries, so that's the reason why we will use registry to set the flag on first run.
And yep, you need to create a reference to "c:\windows\system32\FirewallAPI.dll".

` RegistryKey currentUserKey = Registry.CurrentUser;
RegistryKey softwareKey = currentUserKey.OpenSubKey("SOFTWARE", writable: true);
RegistryKey orgKey = softwareKey.OpenSubKey("%YOUR ORG NAME%", writable: true);

        if (orgKey == null)
            orgKey = softwareKey.CreateSubKey("%YOUR ORG NAME%", writable: true);

        RegistryKey appKey = orgKey.OpenSubKey("%YOUR APPNAME%", writable: true);

        if (appKey == null)
            appKey = orgKey.CreateSubKey("%YOUR APPNAME%", writable: true);

        bool? permissionsGranted = null;

        try
        {
            object keyValue = appKey.GetValue("Permissions Granted");

            permissionsGranted = keyValue != null ? Convert.ToBoolean(keyValue) : false;
        }
        catch (Exception e) {
            permissionsGranted = false;
        }

        if (permissionsGranted == false) {
            appKey.SetValue("Permissions Granted", true);

            Type tNetFwPolicy2 = Type.GetTypeFromProgID("HNetCfg.FwPolicy2");
            INetFwPolicy2 fwPolicy2 = (INetFwPolicy2)Activator.CreateInstance(tNetFwPolicy2);
            var currentProfiles = fwPolicy2.CurrentProfileTypes;

            INetFwRule2 inboundRule = (INetFwRule2)Activator.CreateInstance(Type.GetTypeFromProgID("HNetCfg.FWRule"));
            inboundRule.Enabled = true;
            inboundRule.Action = NET_FW_ACTION_.NET_FW_ACTION_ALLOW;
            inboundRule.Protocol = 6; // TCP
            inboundRule.LocalPorts = "80";
            inboundRule.Name = "HTTP Server 80 port";
            inboundRule.Profiles = currentProfiles;

            INetFwPolicy2 firewallPolicy = (INetFwPolicy2)Activator.CreateInstance(Type.GetTypeFromProgID("HNetCfg.FwPolicy2"));
            firewallPolicy.Rules.Add(inboundRule);
        }

        currentUserKey.Close();
        softwareKey.Close();
        orgKey.Close();
        appKey.Close();`

@skrepecki
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hello world

thanks a lot !! ;)

@rzymski
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rzymski commented Aug 3, 2022

That's what I was looking for. Thank you very much. Good job.

@AlexanderHS
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Been fooling around with this and noticed some unanswered questions above. Can only tell you what worked for me.

"I want to send a json string to the http server. How can I get the message from the request?"

I went with something like:

string payload = GetRequestPostData(ctx.Request);
Where you define that function like:

string GetRequestPostData(HttpListenerRequest request)
{
    if (!request.HasEntityBody)
    {
        return null;
    }
    using (System.IO.Stream body = request.InputStream)
    {
        using (var reader = new System.IO.StreamReader(body, request.ContentEncoding))
        {
            return reader.ReadToEnd();
        }
    }
}

doesn't work with other Networks on the same Network for example a Phone.
I tried changing "url" to the local IP Address of the Machine Running the code, but this doesn't work for neither my Phone or my PC.
Does anyone have a Solution to this?

change localhost to something like + or *
e.g.
string url = $"http://+:8000/";
Your OS might complain about permissions though.

If so you can try something like: "netsh http add urlacl url=http://+:8000/ user=your_username_here"

@nmnmrm
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nmnmrm commented Jul 24, 2024

how do i encode an image to bytes?

@Elias-Traunbauer
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@Tomloyo thats not the right place to ask xD
but since im already here, let me help you.

First you need to load the image into a bitmap.
When you did that, there is a function called LockBits
this returns a pointer to the start of the array.

Then you can just copy all the image bytes into a seperate byte[] you created.

@veso266
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veso266 commented Oct 5, 2024

How could I make this work with SSL Encryption, essentialy have this function as https server

I tried to take TLS part from Kestrel (its to big, I don't need the whole framework), because I need to perform secure connection with OpenSSL (my os doesn't have the newest ciphers uvailable): https://github.com/tmds/KestrelHttpServer/tree/ab78fb0b8ca4f03eb53795f9a97c8152b045ef6b/src/Kestrel.Tls

Here is what I tried to take out: https://github.com/user-attachments/files/17267580/Kestrel.Tls.zip

and this is how I tried using it

using System;
using System.IO;
using System.Text;
using System.Net;
using System.Threading.Tasks;
using Kestrel.Tls;

namespace HttpListenerExample
{
    class HttpServer
    {
        public static HttpListener listener;
        public static string url = "https://192.168.88.12:443/"; // Change to HTTPS and appropriate port
        public static int pageViews = 0;
        public static int requestCount = 0;

        public static string certificatePath = "my-cert.pem";
        public static string privateKeyPath = "my-key.pem";

        public static string pageData =
            "<!DOCTYPE>" +
            "<html>" +
            "  <head>" +
            "    <title>HttpListener Example</title>" +
            "  </head>" +
            "  <body>" +
            "    <p>Page Views: {0}</p>" +
            "    <form method=\"post\" action=\"shutdown\">" +
            "      <input type=\"submit\" value=\"Shutdown\" {1}>" +
            "    </form>" +
            "  </body>" +
            "</html>";

        public static async Task HandleIncomingConnections()
        {
            bool runServer = true;

            while (runServer)
            {
                // Wait for an incoming connection
                HttpListenerContext ctx = await listener.GetContextAsync();
                Stream innerStream = ctx.Response.OutputStream;

                // Wrap the inner stream with TlsStream
                using (var tlsStream = new TlsStream(innerStream, certificatePath, privateKeyPath, new[] { "http/1.1" }))
                {
                    // Perform the TLS handshake
                    await tlsStream.DoHandshakeAsync();

                    // Handle request
                    HttpListenerRequest req = ctx.Request;
                    HttpListenerResponse resp = ctx.Response;

                    // Print out request info
                    Console.WriteLine("Request #: {0}", ++requestCount);
                    Console.WriteLine(req.Url.ToString());
                    Console.WriteLine(req.HttpMethod);
                    Console.WriteLine(req.UserHostName);
                    Console.WriteLine(req.UserAgent);
                    Console.WriteLine();

                    // Handle shutdown request
                    if ((req.HttpMethod == "POST") && (req.Url.AbsolutePath == "/shutdown"))
                    {
                        Console.WriteLine("Shutdown requested");
                        runServer = false;
                    }

                    // Increment page views, ignoring favicon requests
                    if (req.Url.AbsolutePath != "/favicon.ico")
                        pageViews += 1;

                    // Write the response info
                    string disableSubmit = !runServer ? "disabled" : "";
                    byte[] data = Encoding.UTF8.GetBytes(String.Format(pageData, pageViews, disableSubmit));
                    resp.ContentType = "text/html";
                    resp.ContentEncoding = Encoding.UTF8;
                    resp.ContentLength64 = data.LongLength;

                    // Write out to the response stream
                    await tlsStream.WriteAsync(data, 0, data.Length, default);
                }
            }
        }

        public static void Main(string[] args)
        {
            listener = new HttpListener();
            listener.Prefixes.Add(url);
            listener.Start();
            Console.WriteLine("Listening for connections on {0}", url);

            // Handle requests
            Task listenTask = HandleIncomingConnections();
            listenTask.GetAwaiter().GetResult();

            // Close the listener
            listener.Close();
        }
    }
}

But using firefox, I get PR_CONNECT_RESET_ERROR
and when I tried to connect using OpenSSL like this

openssl s_client -connect domain.local:443

I get this as error

Connecting to 192.168.88.12
CONNECTED(00000128)
write:errno=10054
---
no peer certificate available
---
No client certificate CA names sent
---
SSL handshake has read 0 bytes and written 327 bytes
Verification: OK
---
New, (NONE), Cipher is (NONE)
This TLS version forbids renegotiation.
Compression: NONE
Expansion: NONE
No ALPN negotiated
Early data was not sent
Verify return code: 0 (ok)
---

So not sure how to fix my problem
I know my certificates are valid, also I do have libssl-1_1.dll and libcrypto-1_1.dll in my bin directory

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