In c #, HttpWebRequest uses Proxy to implement the domain name request of the specified IP Address

I have the following requirement:

A domain name, xxx.com, is actually followed by many iP addresses: for example:

• 1.2.3.4,
• 5.6.7.8,
• 9.10.11.12

These ip addresses all have the same website. During domain name resolution, a random ip address is assigned to you (this is DNS load balancing ).

However, if I want to access a website on a specific IP address, such as a website on 5.6.7.8, but the website is restricted to be accessible only through a domain name, directly change the domain name to an IP Address url such as http: // 5.6.7.8.

What should we do?

There are two methods:

1. Modify the Hosts file and specify xxx.com to be resolved to 5.6.7.8.

2. Use http: // 5.6.7.8:

Host: xxx.com

 

Because I use C # code to implement this function, I want to solve it in 2nd ways.

 

C # uses the HttpWebRequest class to obtain an http request. It has a Header attribute and can modify the value in the Header. However, according to MSDN, the Host identity cannot be modified in this way. If you use this method:

HttpWebRequest. Headers ["Host"] = "xxx.com ";

It throws an exception:

ArgumentException: The Host header cannot be modified directly.

Can we still meet the above requirements? The answer is yes, but the method should be changed:

The Url still uses the Domain Name:

Http://xxx.com/

 

Set the Proxy attribute of HttpWebRequest to the IP address you want to access, as follows:

HttpWebRequest. Proxy = new WebProxy (ip. ToString ());

 

The reference code is as follows (the code is from reference 1 ):

using System;using System.IO;using System.Net;namespace ConsoleApplication1{    class Program    {        public static void Main(string[] args)        {            HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://www.example.com/Default.aspx");            System.Net.WebProxy proxy = new WebProxy("208.77.186.166", 80);            request.Proxy = proxy;            using (WebResponse response = request.GetResponse())            {                using (TextReader reader = new StreamReader(response.GetResponseStream()))                {                    string line;                    while ((line = reader.ReadLine()) != null)                        Console.WriteLine(line);                }            }        }    }}

 

In this way, the domain name request of the specified IP address is implemented.

Note: Someone has already reported to Microsoft that the host header cannot be modified. Microsoft has reported that a new Host attribute will be added to the next. Net Framewok file, so that the Host header can be modified.

Original article:

By MicrosoftSend the message

 

The next release of the. NET Framework will include a new "Host" property. The value of this property will be sent as "Host" header in the HTTP request.

References:

1. HttpWebRequest. Headers ["Host"] throws an unexpected exception