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Home » Developing U++ » U++ Developers corner » Adding network proxy support to U++
Adding network proxy support to U++ [message #43789] Sun, 12 October 2014 15:45 Go to next message
Oblivion is currently offline  Oblivion
Messages: 1135
Registered: August 2007
Senior Contributor
Hello guys,

One thing I miss in the U++'s network/socket framework is a generic network proxy support.
I am aware that some of the net classes (HttpClient/Pop3, for example) have built-in proxy support, but then, they support only the HTTP_CONNECT tunneling.
While this might be sufficient for the above mentioned classes, other socket operations can and might require listening/binding, in which case SOCKS proxy protocol(s) seem(s) to be the only (or a better) way to go, given the robustness of SOCKS protocol(s).
Also implementing the same code for every different class doesn't seem to me a good idea.

So here's the issue:
What started as a simple proxy code path for my FTP class now turned into a full-blown network proxy class supporting HTTP_CONNECT, SOCKS v4\4a\5 protocols.
Writing a synchronous generic network proxy class is actually very simple, given the simplicity of these widely used protocols.
On the other hand, writing an asynchronous proxy class is a bit harder, because of the increased code complexity, so I used HttpClient as a model.
Currenty I have a working (a)synchronous network class prototype called "NetProxy", which can connect via HTTP or SOCKS servers, using HTTP_CONNECT,SOCK4/4a/5 protocols, which allows both connecting and binding (only on Socks protocol) sockets through the respective proxy servers.

I would like to ask you two questions and hear your opinions on the topic:

1) In its present form, NetProxy class is a simple delegate/wrapper class, which takes a reference to an already constructed TcpSocket instance in its constructor, or through the NetProxy::Client() method, and simply stores a pointer to the socket. The thing is, I am not sure if this is the right or the best approach. Also, I am not sure if it can scale well. İs a generic delegate/wrapper class way to go, or would it be better to have a TcpSocket derived class, say, something like ProxiedTcpSocket? (One advantage of delegate/wrapper class over TcpSocket derived class could be that the existing app code can be modified to take advantage of the proxy connections without too much hassle.)

2) Is an asynchronous (non-blocking) mode which gives some complexity to both api and internal code is good, or would a simple synchronous (blocking) mode suffice?

To give you the picture, here is stripped down version of the actual NetProxy prototype example (in async mode, but with only one socket.):

CONSOLE_APP_MAIN
{
	TcpSocket  s;

//	NetProxy proxy(s, "127.0.0.1", 1080, "anonymous", "anonymous", NetProxy::SOCKS5);

	NetProxy proxy;
	proxy.Client(s);
	proxy.Server("127.0.0.1", 1080);

	proxy.Auth("anonymous", "anonymous");
	proxy.Remote("ftp.uni-erlangen.de", 21);
	SocketWaitEvent we;
	we.Add(s);
		we.Wait(100);
	for(;;) {

		proxy.Do();
		if(!proxy.InProgress()) {
			if(proxy.IsFailure()) {
				Cout() << "Proxy failed.\r\n";
				break;
				
			}
			else
			if(proxy.IsSuccess()) {
				Cout() << s.GetLine() << "\r\n";
				Cout() << "Success!";
				break;
			}
		}
	}
	s.Close();
}



What do you think?
If everything goes well, and after I have reliable code, I will upload the NetProxy to the Bazaar section, in case someone might find it useful.


(I'm not sure if this is the right place to post this, so please feel free to move this topic to the appropriate forum).

Regards,
Oblivion


[Updated on: Sun, 12 October 2014 19:18]

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Re: Adding network proxy support to U++ [message #43793 is a reply to message #43789] Mon, 13 October 2014 15:49 Go to previous messageGo to next message
Mindtraveller is currently offline  Mindtraveller
Messages: 917
Registered: August 2007
Location: Russia, Moscow rgn.
Experienced Contributor

Hi Oblivion,

In my opinion better support for proxies is very good idea. I also suppose both async & sync versions are useful.
We just need to correct it's interface according to U++ network classes style.
Of course, better proxying must be easy to attach to classes like HttpRequest if one needs it.
Re: Adding network proxy support to U++ [message #43802 is a reply to message #43789] Mon, 20 October 2014 17:33 Go to previous messageGo to next message
mirek is currently offline  mirek
Messages: 14105
Registered: November 2005
Ultimate Member
Sounds good!

Mirek
Re: Adding network proxy support to U++ [message #43853 is a reply to message #43789] Sun, 09 November 2014 16:56 Go to previous messageGo to next message
Oblivion is currently offline  Oblivion
Messages: 1135
Registered: August 2007
Senior Contributor
Hello Mindtraveller, Mirek.
Thank you for your suggestions. And I apologize I couldn't reply earlier, I was away for a while.

Here is what happened meanwhile:

After some toying with the network proxy idea for U++, I concluded that writing a monolithic, all-in-one network proxy class wouldn't be very effective (also imho, it would not be so upp-ish) way to implement it.

So I ditched the somewhat bloated, monolithic NetProxy class in favour of a modular approach, and abstracted a common interface and code for sync/async network proxies. This abstract class I called NetworkProxy. It contains all the necessary elements so far to succesfully implement most popular types of network proxy protocols. It has some advantages: Permits adding new/other sync/async network proxy protocols easily, relatively faster than NetProxy (due to less control code). Also we now have polymorphism: With this approach we can use a single Array object to contain a collection of different types of proxy instances if needed.

NetworkProxy abstract class currently has three derivatives with almost-identical interface: HttpProxy, Socks4Proxy, Socks5Proxy.

Here is the current "public" interface of NetworkProxy class and its derivatives (Note that SSL support and binding methods (in SOCKS4/5 proxies) are not yet implemented):
class NetworkProxy
{
  
public:
    enum ProxyType      { HTTP = 1, SOCKS4, SOCKS5 };
        
    NetworkProxy&       Attach(TcpSocket& sock)                         
    NetworkProxy&       Host(const String& host)    
    NetworkProxy&       Port(int port)                              
    NetworkProxy&       Timeout(int ms)                             

    TcpSocket*          GetSocket() const                           
    int                 GetType() const                               

    bool                Connect(const String& host, int port);
    void                StartConnect(const String& host, int port);
    virtual bool        Do() = 0;

    bool                InProgress() const                        
    bool                IsSuccess() const                      
    bool                IsFailure() const                           

    String              GetErrorDesc() const                     

    NetworkProxy();
    virtual ~NetworkProxy();    
};

class HttpProxy : public NetworkProxy
{
  
public:
    HttpProxy&          Auth(const String& user, const String& pass) 
    bool                Do();
    
    HttpProxy();
    HttpProxy(TcpSocket& sock, const String& host, int port, const String& user = Null, const String& pass = Null);
    ~HttpProxy();
};

class Socks4Proxy : public NetworkProxy
{
   
public:
    Socks4Proxy&        Auth(const String& user)                
    bool                Do();
    
    Socks4Proxy();
    Socks4Proxy(TcpSocket& sock, const String& host, int port, const String& user = Null);
    ~Socks4Proxy();
};


class Socks5Proxy : public NetworkProxy
{
 
public:
    Socks5Proxy&        Auth(const String& user, const String& pass)     
    bool                Do();
    
    Socks5Proxy();
    Socks5Proxy(TcpSocket& sock, const String& host, int port, const String& user = Null, const String& pass = Null);
    ~Socks5Proxy();
};


As Mindtraveller suggested, I corrected the interface, but any further corrections, suggestions or ideas are always welcome.

To give you further idea, here is the actual and complete working example code of async HTTP_CONNECT proxy (It simply connects to five different Ftp servers via a public http proxy and gets the server greeting):

#include <Core/Core.h>
#include <NetworkProxy/NetworkProxy.h>

using namespace Upp;

CONSOLE_APP_MAIN
{
	
	static const char *target_hosts[] = {
		"ftp.uni-erlangen.de",	// Aminet ftp server.
		"ftp.mozilla.org",	// Mozilla ftp server.
		"ftp.freebsd.org",	// FreeBSD ftp server.
		"ftp.microsoft.com",	// Microsoft ftp server.
		"ftp.kde.org",		// KDE ftp server.
	};
	
	Array<TcpSocket> sockets;
	Array<HttpProxy> proxies;
	SocketWaitEvent socketevent;

	for(int i = 0; i < 5; i++) {
		TcpSocket& socket = sockets.Add();
		socketevent.Add(socket);
		HttpProxy& proxy = proxies.Add();
		proxy.Attach(socket);
		proxy.Host("97.77.104.22");
		proxy.Port(80);
		proxy.StartConnect(target_hosts[i], 21);
	}
		
	while(proxies.GetCount()) {
		socketevent.Wait(10);
		for(int i = 0; i < proxies.GetCount(); i++) {
			HttpProxy& proxy = proxies[i];
			proxy.Do();
			if(!proxy.InProgress()) {
				if(proxy.IsFailure())
					Cout() << "Proxy connection failed. Reason: " << proxy.GetErrorDesc() << "\r\n";
				else
				if(proxy.IsSuccess()) {
					TcpSocket *socket = proxy.GetSocket();
					Cout() << "Succesfully connected via: " << socket->GetPeerAddr() << "\r\n";
					Cout() << socket->GetLine() << "\r\n";
				}
				proxies.Remove(i);
				break;
			}
		}
	}
	
	for(int i = 0; i < sockets.GetCount(); i++)
		sockets[i].Close();
}


There are some small quirks to iron out, but I am planning to upload the complete package next weekend.

Regards,
Oblivion.






[Updated on: Sun, 09 November 2014 17:14]

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Re: Adding network proxy support to U++ [message #43863 is a reply to message #43853] Wed, 12 November 2014 08:12 Go to previous messageGo to next message
mirek is currently offline  mirek
Messages: 14105
Registered: November 2005
Ultimate Member
Sounds pretty good, looking forward to the code...

Mirek
Re: Adding network proxy support to U++ [message #43937 is a reply to message #43863] Sat, 22 November 2014 14:56 Go to previous messageGo to next message
Oblivion is currently offline  Oblivion
Messages: 1135
Registered: August 2007
Senior Contributor
Hello Mirek,

Here I upload the code for review (I can move it to the Bazaar section, if you prefer). It is a complete package, contains API docs and two examples (examples are rudimentary though).
This is the first public version, and contains the NetworkProxy, HttpProxy and SocksProxy classes.
As I mentioned before, I used HttpRequest class as a model (and borrowed some of its code too).

Comments, bug reports, fixes, constructive criticism are always welcome.

P.s. If you find it of enough quality, please feel free to add it to U++.

[Package Removed. You can find the final version below]
Regards,
Oblivion


[Updated on: Thu, 25 December 2014 23:07]

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Re: Adding network proxy support to U++ [message #43948 is a reply to message #43863] Mon, 24 November 2014 14:34 Go to previous messageGo to next message
Oblivion is currently offline  Oblivion
Messages: 1135
Registered: August 2007
Senior Contributor
Hello Mirek,

There was a bug with the Socks4Request() method. It is now fixed.
Please find the fixed package attached below.

[Package Removed. You can find the final version below]

Regards,
Oblivion.


[Updated on: Thu, 25 December 2014 23:07]

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Re: Adding network proxy support to U++ [message #44056 is a reply to message #43789] Fri, 19 December 2014 15:39 Go to previous messageGo to next message
Oblivion is currently offline  Oblivion
Messages: 1135
Registered: August 2007
Senior Contributor
Hello guys,

I've been away for a while.

Any comments on the current NetworkProxy package code?
Do you find it sufficient? Or Is it lacking any necessary features? If so, which are they?
Did you find any bugs?
Is it of enough quality?

I use the package and It works fine here, but any feedback and testing would be very helpful developing it further.
Smile

Regards,
Oblivion.


Re: Adding network proxy support to U++ [message #44090 is a reply to message #44056] Wed, 24 December 2014 12:12 Go to previous messageGo to next message
mirek is currently offline  mirek
Messages: 14105
Registered: November 2005
Ultimate Member
Oblivion wrote on Fri, 19 December 2014 15:39
Hello guys,

I've been away for a while.

Any comments on the current NetworkProxy package code?
Do you find it sufficient? Or Is it lacking any necessary features? If so, which are they?
Did you find any bugs?
Is it of enough quality?

I use the package and It works fine here, but any feedback and testing would be very helpful developing it further.
Smile

Regards,
Oblivion.


I am sorry for delays. I have in 'todo' list, among bazillion of other things.

One problem is that I have a little practical use for it right now (never had to use other than already supported proxies in my production environments)... hence the slow response.

Mirek
Re: Adding network proxy support to U++ [message #44095 is a reply to message #44090] Wed, 24 December 2014 12:53 Go to previous messageGo to next message
Oblivion is currently offline  Oblivion
Messages: 1135
Registered: August 2007
Senior Contributor
Hello Mirek,

No problem, and of course I understand that you are very busy. Smile
Please feel free to review it anytime you find it ok to review.

By the way, I can move the package to Bazaar section of this forum, if you prefer.



Regarads,
Oblivion.


[Updated on: Wed, 24 December 2014 12:55]

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Re: Adding network proxy support to U++ [message #44120 is a reply to message #44095] Thu, 25 December 2014 21:03 Go to previous messageGo to next message
mirek is currently offline  mirek
Messages: 14105
Registered: November 2005
Ultimate Member
Well... I wanted it to go directly to something like Core/Proxy...

Mirek
Re: Adding network proxy support to U++ [message #44122 is a reply to message #44120] Thu, 25 December 2014 23:06 Go to previous messageGo to next message
Oblivion is currently offline  Oblivion
Messages: 1135
Registered: August 2007
Senior Contributor
Hello Mirek,

As always, I'd be happy to contribute to U++. Smile
If you need my explicit permission, then permission is granted. You can freely add the NetworkProxy package to U++ if you find it of enough quality. (BSD licence is added to the package.)
I was going to upload it to bazaar, because people may look into that section for some new code/classes, and I understand that you are busy.
So here I upload the final code. Below package is, I believe, a complete package covering the basic HTTP and SOCKS4/4a/5 proxy protocols.
One more convenience function, ProxyAccept(), is added, which drastically simplifies SOCKS BIND requests.
From now on, and until you ask from me otherwise, the package is in maintenance mode. I am not going to add any other functions or a new class unless it's neccessary. Only bug fixes, etc. will happen.


Regards,
Oblivion.


[Updated on: Mon, 29 December 2014 13:13]

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Re: Adding network proxy support to U++ [message #44124 is a reply to message #44122] Sat, 27 December 2014 14:37 Go to previous messageGo to next message
Klugier is currently offline  Klugier
Messages: 1083
Registered: September 2012
Location: Poland, Kraków
Senior Contributor
Hello Oblivion,

Little review for your code. Never use "using namespace Upp" in your header files (.h). More information you can find on StackOverflow: http://stackoverflow.com/questions/5849457/using-namespace-i n-c-headers. Instead of "using namespace Upp" use "NAMESPACE_UPP & END_UPP_NAMESPACE" construction:

NAMESPACE_UPP

class NetworkProxy
{
  ...
}

END_UPP_NAMESPACE



But in implementation (.cpp file) you will need to use "using namespace Upp;" directive or "NAMESPACE_UPP & END_UPP_NAMESPACE" construction. It dosen't metter in implementation file. Personally, I prefer first option, but for example core Upp code use second option.

Sincerely,
Klugier


U++ - one framework to rule them all.

[Updated on: Sat, 27 December 2014 14:38]

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Re: Adding network proxy support to U++ [message #44127 is a reply to message #44124] Mon, 29 December 2014 13:12 Go to previous message
Oblivion is currently offline  Oblivion
Messages: 1135
Registered: August 2007
Senior Contributor
Hello Klugier,

Thank you very much for reviewing the code, and, of course, for the informative article.
You are right, it is a bad habit, I overlooked the possible problems it can result in. It is now fixed.

Regards,
Oblivion.


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