Listen for Http Requests with Unity

UnityHttpListener.cs

using UnityEngine;
using UnityEngine.Networking;
using System;
using System.IO;
using System.Net;
using System.Threading;

public class UnityHttpListener : MonoBehaviour
{

	private HttpListener listener;
	private Thread listenerThread;

	void Start ()
	{
		listener = new HttpListener ();
		listener.Prefixes.Add ("http://localhost:4444/");
		listener.Prefixes.Add ("http://127.0.0.1:4444/");
		listener.AuthenticationSchemes = AuthenticationSchemes.Anonymous;
		listener.Start ();

		listenerThread = new Thread (startListener);
		listenerThread.Start ();
		Debug.Log ("Server Started");
	}

	void Update ()
	{		
	}

	private void startListener ()
	{
		while (true) {               
			var result = listener.BeginGetContext (ListenerCallback, listener);
			result.AsyncWaitHandle.WaitOne ();
		}
	}

	private void ListenerCallback (IAsyncResult result)
	{				
		var context = listener.EndGetContext (result);		

		Debug.Log ("Method: " + context.Request.HttpMethod);
		Debug.Log ("LocalUrl: " + context.Request.Url.LocalPath);

		if (context.Request.QueryString.AllKeys.Length > 0)
			foreach (var key in context.Request.QueryString.AllKeys) {
				Debug.Log ("Key: " + key + ", Value: " + context.Request.QueryString.GetValues (key) [0]);
			}

		if (context.Request.HttpMethod == "POST") {	
			Thread.Sleep (1000);
			var data_text = new StreamReader (context.Request.InputStream, 
				                context.Request.ContentEncoding).ReadToEnd ();
			Debug.Log (data_text);
		}

		context.Response.Close ();
	}

}

ThatOtherVRGuy Check out the IPManager class in this thread on StackExchange. It will grab the IP address for you.

https://stackoverflow.com/questions/51975799/how-to-get-ip-address-of-device-in-unity-2018

You can also bind to ip address 127.0.0.1 (localhost) or simply or use a wildcard (though it's not always a good thing to bind to all IP addresses on a system.)

I would also like to comment on the topic of treads vs. coroutines. Coroutines are great for in-game things that you can guarantee will happen quickly and/or can be sliced neatly into sections to spread across frames. The nature of HTTP, however, cannot guarantee any sort of timing and from my experience should generally be done in a separate thread. This, of course, does depend a lot on what you're doing with it.