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simple redirect a local port to a remote port

PortRedirect proc pDestIP:DWORD,SrcSock:DWORD,DestPort:DWORD

LOCAL	sockAddr:sockaddr_in

LOCAL	DestSock:DWORD

LOCAL	tempBuffer[4096]:byte



;Establish destination socket

invoke	inet_addr,pDestIP

lea	edx, sockAddr

mov	ecx, DestPort

xchg 	cl, ch	; convert to network byte order

mov	[edx][sockaddr_in.sin_family], AF_INET	

mov	[edx][sockaddr_in.sin_port], cx

mov	[edx][sockaddr_in.sin_addr.S_un.S_addr], eax

invoke	socket, AF_INET, SOCK_STREAM, IPPROTO_TCP

mov	DestSock,eax

invoke 	connect, DestSock, addr sockAddr, sizeof sockAddr



;Relay request header

invoke	recv,SrcSock,addr tempBuffer,4096,NULL	;Get request header

invoke	send,DestSock,addr tempBuffer,eax, 0	;Relay request header

test	eax, eax

jz		_connectionClosed	;0 return means connection closed

cmp		eax, SOCKET_ERROR

je		_error



;Relay data

_recvLoop:

	invoke	recv, DestSock,addr tempBuffer, 4096, 0

	test	eax, eax

	jz		_connectionClosed

	cmp		eax, SOCKET_ERROR

	je		_error

	invoke	send, SrcSock,addr tempBuffer,eax,0	;Relay data

	cmp		eax, SOCKET_ERROR

	je		_error



	jmp		_recvLoop



_connectionClosed:

	invoke	closesocket, SrcSock

	invoke	closesocket, DestPort

	ret

	

_error:

	invoke	WSAGetLastError

	debug

	jmp		_connectionClosed



PortRedirect endp

@optimus: Really neat work! :alright:

@Mikky: This is a TCP/IP bouncer, so it works for any protocol that works with TCP. Actually proxies are quite more complicated, as they work like HTTP servers themselves.

Posted on 2003-10-18 15:53:07 by QvasiModo

Well, http-proxies do a lot more than simple bouncing. For example, they can alter the http headers, or cache the data downloaded by different users. Besides, a simple TCP/IP relayer always redirects everything to the same IP and port... there's no way to configure it (unless you set up another port to do that).
As for socks proxies, I don't know much about them, but I guess it must be a similar case.