Tuesday, October 04, 2005

Sniffer and Reactor/Proactor

While I have used pcap and winpcap for years, I am not big fan of the current programming model. I would wish to have an event driven model(reactor) or asynchronous IO model(procator). In other words, treat PCAP handler just like socket, have someone (select() for example) notify me when something interesting happens.

But maybe it is not pcap to blame, most of time it is just implemented as an user level library, and the underlying operating system may not provide a way to do IO multiplexing for such low level functions.

To implement a sniffer on windows, most of people will go for winpcap (btw, after a long waiting(two years!), winpcap 3.1 is finally out to replace the very buggy 3.0 version). Actually winsock has native sniffing support via raw socket(with SIO_RCVALL option), and it works well with reactor and proactor!

Here is the code to demonstrate the functionality (I used ACE. I know most of people would prefer plain old socket programming, but it is too hard for me to go back the dark days):


//Sniffer and Reactor Example
#include <ace/Log_Msg.h>
#include <ace/Reactor.h>
#include <ace/INET_Addr.h>
#include <ace/OS.h>
#include <ace/WFMO_Reactor.h>

#include <mstcpip.h>//SIO_RCVALL

//ACE_NDEBUG will be defined if you define _DEBUG on windows.
#ifdef ACE_NDEBUG
#define ACE_VERIFY(X) ((void)(X))
#else
#define ACE_VERIFY(X) ACE_ASSERT(X)
#endif //ACE_NDEBUG

class Sniffer : public ACE_Event_Handler
{
public:
Sniffer(ACE_Reactor& reactor)
:socket_(ACE_INVALID_HANDLE)
{
this->reactor(&reactor);
}

ACE_HANDLE get_handle() const
{
return socket_;
}

~Sniffer()
{
if (ACE_INVALID_HANDLE != socket_)
{
ACE_VERIFY(ACE_OS::closesocket(socket_) == 0);
}
}

/*
MSDN On SIO_RCVALL:
Enables a socket to receive all IP packets on the network. The socket handle passed to the
WSAIoctl function must be of AF_INET address family, SOCK_RAW socket type, and IPPROTO_IP
protocol. The socket also must be bound to an explicit local interface, which means that you cannot
bind to INADDR_ANY.
Once the socket is bound and the ioctl set, calls to the WSARecv or recv functions return IP
datagrams passing through the given interface. Note that you must supply a sufficiently large
buffer. Setting this ioctl requires Administrator privilege on the local computer. SIO_RCVALL is
available in Windows 2000 and later versions of Windows.
*/

int open (const ACE_INET_Addr& listen_addr)
{
socket_ = ACE_OS::socket(AF_INET, SOCK_RAW, IPPROTO_IP);
if (ACE_INVALID_HANDLE == socket_)
{
ACE_ERROR((LM_ERROR, ACE_TEXT("%p\n"), ACE_TEXT("socket() failed in Sniffer::open()")));
return -1;
}

sockaddr* laddr = reinterpret_cast<sockaddr*>(listen_addr.get_addr());
size_t size = listen_addr.get_size();
ACE_VERIFY(ACE_OS::bind(socket_, laddr, size) == 0);

DWORD YES = 1;
ACE_VERIFY(ACE_OS::setsockopt(socket_, IPPROTO_IP, IP_HDRINCL, reinterpret_cast<const char*>(&YES), sizeof(YES)) == 0);

DWORD dwBytesRet = 0 ;
if (WSAIoctl((SOCKET)socket_, SIO_RCVALL, &YES, sizeof(YES), NULL, 0, &dwBytesRet, NULL, NULL) != 0)
{
ACE_ERROR((LM_ERROR, ACE_TEXT("%p\n"), ACE_TEXT("WSAIoctl() failed in Sniffer::open()")));
return -1;
}

DWORD rcvtimeo = 1000 ; // 1 sec instead of 45(default)
ACE_VERIFY(ACE_OS::setsockopt(socket_, SOL_SOCKET, SO_RCVTIMEO, reinterpret_cast<const char*>(&rcvtimeo) , sizeof(rcvtimeo)) == 0);

// register the event handle
if( this->reactor()->register_handler(this, ACE_Event_Handler::READ_MASK) < 0)
{
ACE_ERROR((LM_ERROR, ACE_TEXT ("%p\n"),
ACE_TEXT("register_handler")));
return -1;
}

ACE_DEBUG((LM_DEBUG, ACE_TEXT("Sniffer::open\n")));
return 0;
}

int handle_input(ACE_HANDLE fd = ACE_INVALID_HANDLE)
{
ACE_ASSERT(fd == socket_);

char recvbuf[65536] = {0};
ssize_t nrecv = ACE_OS::recv(socket_, recvbuf, sizeof(recvbuf) - 1);
if (nrecv > 0)
{
ACE_HEX_DUMP((LM_NOTICE, recvbuf, nrecv));
}
else
{
ACE_ERROR((LM_ERROR, ACE_TEXT("handle_input returns %d: %m\n"), nrecv));
}

return 0;
}

private:
ACE_HANDLE socket_;
};

int ACE_TMAIN(int /*argc*/, ACE_TCHAR** /*argv*/)
{
ACE_WFMO_Reactor wfmo_reactor;
ACE_Reactor reactor (&wfmo_reactor);

//TODO bind to your local address!!!
//Do not work with loopback address (127.0.0.1)
ACE_INET_Addr addr("192.168.0.100:0");

Sniffer sniffer(reactor);
if (sniffer.open(addr) == -1)
{
ACE_ERROR((LM_ERROR, ACE_TEXT("Can not open to listen: %m\n")));
return -1;
}

//Run event loop
ACE_DEBUG((LM_NOTICE, ACE_TEXT("Sniffer started\n")));
reactor.run_reactor_event_loop();
return 0;
}


--------------------------------


//Sniffer and Proactor example
#include <ace/Log_Msg.h>
#include <ace/INET_Addr.h>
#include <ace/OS.h>
#include <ace/Proactor.h>
#include <ace/WIN32_Proactor.h>

#include <mstcpip.h>//SIO_RCVALL

//ACE_NDEBUG will be defined if you define _DEBUG on windows.
#ifdef ACE_NDEBUG
#define ACE_VERIFY(X) ((void)(X))
#else
#define ACE_VERIFY(X) ACE_ASSERT(X)
#endif //ACE_NDEBUG

class Sniffer : public ACE_Handler
{
static const size_t PACKET_SIZE = 65526;
public:
Sniffer(ACE_Proactor& proactor)
:socket_(ACE_INVALID_HANDLE)
,ACE_Handler(&proactor)
,mblk_(PACKET_SIZE)
{
}

ACE_HANDLE handle() const
{
return socket_;
}

~Sniffer()
{
if (ACE_INVALID_HANDLE != socket_)
{
ACE_VERIFY(ACE_OS::closesocket(socket_) == 0);
}
}

/*
MSDN On SIO_RCVALL:
Enables a socket to receive all IP packets on the network. The socket handle passed to the
WSAIoctl function must be of AF_INET address family, SOCK_RAW socket type, and IPPROTO_IP
protocol. The socket also must be bound to an explicit local interface, which means that you cannot
bind to INADDR_ANY.
Once the socket is bound and the ioctl set, calls to the WSARecv or recv functions return IP
datagrams passing through the given interface. Note that you must supply a sufficiently large
buffer. Setting this ioctl requires Administrator privilege on the local computer. SIO_RCVALL is
available in Windows 2000 and later versions of Windows.
*/

int open (const ACE_INET_Addr& listen_addr)
{
if (create_sniffer_socket(listen_addr) < 0)
{
return -1;
}

// register the event handle
if (reader_.open(*this) < 0)
{
ACE_ERROR((LM_ERROR, ACE_TEXT("open: %m\n")));
return -1;
}

ACE_DEBUG((LM_DEBUG, ACE_TEXT("Sniffer::open\n")));

//initiate our first asynchronous read
reader_.read(mblk_, PACKET_SIZE);

return 0;
}

void handle_read_stream(const ACE_Asynch_Read_Stream::Result &result)
{
if (!result.success() || result.bytes_transferred() == 0)
{
ACE_ERROR((LM_ERROR, ACE_TEXT("read_streamhandle_read_stream error\n")));
return;
}

ACE_ASSERT(&mblk_ == &result.message_block());

ACE_HEX_DUMP((LM_NOTICE, mblk_.rd_ptr(), result.bytes_transferred()));

//Reset the write pointer and read again
mblk_.wr_ptr(mblk_.rd_ptr());
reader_.read(mblk_, PACKET_SIZE);
}

private:
ACE_Asynch_Read_Stream reader_;
ACE_HANDLE socket_;
ACE_Message_Block mblk_;

int create_sniffer_socket(const ACE_INET_Addr& listen_addr)
{
socket_ = ACE_OS::socket(AF_INET, SOCK_RAW, IPPROTO_IP);

if (ACE_INVALID_HANDLE == socket_)
{
ACE_ERROR((LM_ERROR, ACE_TEXT("%p\n"), ACE_TEXT("socket() failed in Sniffer::open()")));
return -1;
}

sockaddr* laddr = reinterpret_cast<sockaddr*>(listen_addr.get_addr());
size_t size = listen_addr.get_size();
ACE_VERIFY(ACE_OS::bind(socket_, laddr, size) == 0);

DWORD YES = 1;
ACE_VERIFY(ACE_OS::setsockopt(socket_, IPPROTO_IP, IP_HDRINCL, reinterpret_cast<const char*>(&YES), sizeof(YES)) == 0);

DWORD dwBytesRet = 0 ;
if (WSAIoctl((SOCKET)socket_, SIO_RCVALL, &YES, sizeof(YES), NULL, 0, &dwBytesRet, NULL, NULL) != 0)
{
ACE_ERROR((LM_ERROR, ACE_TEXT("%p\n"), ACE_TEXT("WSAIoctl() failed in Sniffer::open()")));
return -1;
}

DWORD rcvtimeo = 1000 ; // 1 sec instead of 45(default)
ACE_VERIFY(ACE_OS::setsockopt(socket_, SOL_SOCKET, SO_RCVTIMEO, reinterpret_cast<const char*>(&rcvtimeo) , sizeof(rcvtimeo)) == 0);

return 0;
}
};

int ACE_TMAIN(int /*argc*/, ACE_TCHAR** /*argv*/)
{
ACE_WIN32_Proactor win32_proactor;
ACE_Proactor proactor(&win32_proactor);

//TODO bind to your local address!!!
//Do not work with loopback address (127.0.0.1)
ACE_INET_Addr addr("192.168.0.100:0");

Sniffer sniffer(proactor);
if (sniffer.open(addr) == -1)
{
ACE_ERROR((LM_ERROR, ACE_TEXT("Can not open to listen: %m\n")));
return -1;
}

//Run event loop
ACE_DEBUG((LM_NOTICE, ACE_TEXT("Sniffer started\n")));
proactor.proactor_run_event_loop();
return 0;
}



Reference:
[0] Raw Sockets in Windows 2000/XP" by ziss

3 Comments:

Blogger Ben said...

yawl: How do you format codes? I can't even put < in blogger.com's blog.

6:12 PM  
Blogger yawl said...

Hey Ben,
Blogger accepts html, but sometimes you need to encode the tag.
Google "code highlighter" you can find several online tools, for example:
http://www.chami.com/colorizer/
http://www.prettyprinter.de/index.php

7:49 AM  
Blogger Ben said...

Thank you, the links are helpful.

The problem of Blogger is: You can use less than sign, but when you want to edit the same page again, everything is wrong.

btw: the link to ACE is wrong.

8:36 AM  

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