I'm trying to write a Home Proxy Server in C# and I almost succeeded but I have problem to handle HTTPS requests (CONNECT).
I don't know really how to handle this type of requests.
In my studies I realized that for this requests we must to connect client to target host directly.
Steps for these requests (that I realized):
Receive first request from client (CONNECT https://www.example.ltd:443 HTTP/1.1) and send that to target host
Send HTTP/1.1 200 Connection Established\r\n\r\n to client
Listen to both sockets (client and target host) and send receives from each other to each other
Listen until one of sockets disconnected
Is this correct? If it ok, how handle this by c# ?
My understanding is that the
CONNECT www.example.com:443 HTTP/1.1
from the browser is asking you to establish a connection to example.com on port 443. Once this has been successfully achieved, you should THEN send the
HTTP/1.1 200 Connection established\r\n\r\n
string back to the browser. You do not send the CONNECT string to the server as I think you were doing. Also, this initial connection SHOULD NOT be encrypted.
From this point, the browser and end server will exchange data over the plain text connection which you must forward to the correct destination. To do this, the socket must remain open. However, the order of communication is not specified, so don't rely on the browser sending data followed by a response from server. Either could send data at any point. They will first establish their own secure connection, then begin to do the usual http requests.
Hope this helps.
References:
https://stackoverflow.com/a/24195792/1224132
https://datatracker.ietf.org/doc/html/draft-luotonen-ssl-tunneling-03
http://www.ietf.org/rfc/rfc2817.txt
Related
I am using Tcplistener to listen on a port for requests. When the requests come in from the client I want to know the client ip making the request.
the problem is : the server and all client take the same Ip
so I decided to send massage from server to client by port ... I search a lot on google But I did not knew how I can send message from server to client using the port ? so can any body help me ?
The clients are not listening for incoming connections, so the only way for the server to send a message to a client is by using an existing connection, that was previously established by the client.
You don't have to specify the port number when sending a message on an existing connection, your server can just use:
Socket handlerSocket = tcpListener.AcceptSocket();
// a connection is now established, "handlerSocket" can be used for both receiving and sending messages
handlerSocket.Send(...);
Your clients currently send data and immediately close the connection though, you'll have to modify them to read data from the NetworkStream in order to receive anything.
There are tons of tutorials available, I think you just googled the wrong keywords. Have you tried something like c# chat tutorial?
You are running them all in the same computer. That is why the IP is always the same.
SOP for this kind of thing is to have two ports: a control port and a data port.
The way this works is:
The control port is used to initiate the connection.
Upon successful connection, the server and the client negotiate a set of ports to be used for the data (local server data port and remote client data port).
The server establishes a connection to the remote client data port from the local server data port.
The client issues a request for data (e.g. command) through the control port.
The server sends the information back through the data port.
I am developing a game in Flex.
There are both AIR and Web versions of this game.
AIR app would connect to a server using a UDP socket on a port.
The purpose of the Web version is to allow users to play when they are at work, or on a computer behind some firewall/proxy that blocks some ports. So the web would connect to a server using http connection on port 80.
The server code answering the http connections would be a java servlet that uses BlazeDS.
But if any of you find it more easier to explain for a C# server code(webservices or whatever), it would be ok .
The server code answering the UDP requests would be a simple class listening for socket connections.
My problem is I don't know how to put UDP and http code together. If there are 5 AIR clients, and 5 Web clients, they all need to meet in the server in some common collection variable, so that I can update all clients with latest info.
Who is going to instantiate the class that listens for sockets? And when?
So to summarize:
1. Do I need a dedicated server to achieve what I want?
2. Who will instantiate the udp handling class and when?
3. Is it even possible to keep the udp handling class and the servlet for http connections together? If there would not be http, I wouldn't even need tomcat. But http and udp code need to stay together, so that I can update the players collection. Is it possible to instantiate the UDP handling class and tell it to listen for socket when the servlet is deployed on the server...or something like that?
Any advices are more then welcome.
Thanks in advance,
Miha
http and udp code need to stay together
No they don't. They are transport mechanisms for your game data, so they should be transparent. Your UDP and HTTP servers should connect to your game backend, in what way is up to you. It can be in-memory, by using HTTP and UDP (socket) modules directly from your backend code, or it could be using some sort of service (so you can let other channels talk to the same backend).
This game backend does not connect directly to the user but only talks to the UDP and HTTP modules.
Then from this backend you process messages you receive from both HTTP and UDP, and sends the response over the same channel.
Example:
AIR-client 1 sends a valid login message to UDP server.
UDP server forwards the login message to the game backend.
Game backend returns succesful result message to UDP server
UDP server forwards the result message to AIR-client 1.
Example 2:
Now HTTP-client 1, which happens to be already logged in, requests all users currently logged in. It does so over HTTP, to the HTTP server.
HTTP server forwards this request to the game backend.
Game backend returns information to HTTP server
HTTP server returns response to client.
I have custom tcp server listening on port 5888(dummy port). The proxy server listens for incoming connections. When the proxy receives a HTTP Request, it should relay the same request to a different server.
Eg:
Proxy receives: http://proxyserver.com/mypage.html
Proxy should Relay: http://MainServer.com/mypage.html
The response from the Main Server should be sent directly to the requesting client.
I have used sockets for accepting connections and parsing the raw HTTP Request before relaying the new HTTP request to the main server. This is becoming too complicated, since I have to send the Raw HTTP Request to the main server, get the response and send it to the client machine.The proxy is basically becoming a middle-man. I want the proxy only for the
one side of communication i.e to change the host address to the MainServer and then the main server should take care of sending the response to the requesting client.
How to achieve this ?
HTTP works over a TCP connection initiated from a client to a server. In presence of proxy you need at least two connections - one from client to the proxy, and one from proxy to the server. These two connections are sort of "independent" in a sense that both transmit standard HTTP requests and responses. Proxy here acts as a client to the end server.
What you want involves at least three TCP connections, and requires sending HTTP response on a different connection from the one where initiating HTTP request came on. That is outside of the HTTP proper - the client wouldn't know that it needs a second connection somewhere else, and how to match requests on one connection to responses on the other. The best you can do within HTTP is redirecting to a different server, say, with a special generated URL or something.
Just remember that HTTP response has to come on the same TCP connection as the original request.
I'm building a UDP server that handles each incoming request in a separate
thread. The problem is, a UDP client may send out multiple requests
concurrently by using multiple threads. Each thread on the client will wait
for responses from the server. Since UDP is connectionless, a client thread
may receive a mismatching datagram. In this case, does have any
built-in mechanism or pattern that helps a client thread to get the matching response?
(for example send each request from server to specific udp port !!?)
I don't want use queue because it lost concurrently property.
If not, I guess we can build a queue that dispatches responses to
appropriate client threads. However, what if I need to run multiple clients
in different JVMs on the same client machine, and each client will make
requests to the same server?
Use a separate socket for each udp client. That way you have a different ip and port for sending and would receive response on the same i.e. the client which sent the request would only receive it's response (i presume that is what you meant by matching) This should be done automatically unless you share the same socket between threads and use it to send messages to server which seems like a bad idea.
You can set any port in your source (sender port) in client before sending message to server. The server can extract your source port and respond to the same port
e.g.
Client 1 source port:10401 -> server:listening port:2000. Server responds to port 10401.
Client 2 source port:10402 -> server: listening port: 2000. Server responds to port 10402.
If you are wanting to do concurrent connections, make multiple connections. Spawn a new UDP connection on the client, the server will just open a new connection on it's end. Anything sent on connection1 on the client comes in on comes on on connection1 on the server, anything sent on connection2 gets received on connection 2.
i want to create a proxy server or (Socks host ??) to communicate with browsers (such as firefox) to forward http proxy.
i have a software that do this: bitvise tunnelier.
so, i need to write an application similiar to tunnelier proxy forwarder.
in other words, i want to enable firefox Socks Host and get browser request with c# application
Please help me lead the way
thanks a lot
Create a proxy means that your application need to act as an HTTP Server when talking to the clients (the browsers) and act as a browser when comunicating with the web sites.
The proxy opens a port for the server socket (for example port 90) and accepts the browser request on this port, than connect the web site (generally on port 80) and forward the request to the site server. The proxy waits for the server response, read it and after send the response to the client.
The proxy changes the messages header if needed ( for example change the port in the url).
In general proxy are multi thread applications, so they can manage more request in the same time.