l2_packet_winpcap.c File Reference

WPA Supplicant - Layer2 packet handling with WinPcap RX thread. More...

#include "includes.h"
#include <pcap.h>
#include "common.h"
#include "eloop.h"
#include "l2_packet.h"

Include dependency graph for l2_packet_winpcap.c:

Go to the source code of this file.

Data Structures
struct	l2_packet_data
Functions
int	l2_packet_get_own_addr (struct l2_packet_data *l2, u8 *addr)
	Get own layer 2 address.
int	l2_packet_send (struct l2_packet_data *l2, const u8 *dst_addr, u16 proto, const u8 *buf, size_t len)
	Send a packet.
l2_packet_data *	l2_packet_init (const char *ifname, const u8 *own_addr, unsigned short protocol, void(*rx_callback)(void *ctx, const u8 *src_addr, const u8 *buf, size_t len), void *rx_callback_ctx, int l2_hdr)
	Initialize l2_packet interface.
void	l2_packet_deinit (struct l2_packet_data *l2)
	Deinitialize l2_packet interface.
int	l2_packet_get_ip_addr (struct l2_packet_data *l2, char *buf, size_t len)
	Get the current IP address from the interface.
void	l2_packet_notify_auth_start (struct l2_packet_data *l2)
	Notify l2_packet about start of authentication.

---

Detailed Description

WPA Supplicant - Layer2 packet handling with WinPcap RX thread.

Copyright

Copyright (c) 2003-2006, Jouni Malinen <[email protected]>

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License version 2 as published by the Free Software Foundation.

Alternatively, this software may be distributed under the terms of BSD license.

See README and COPYING for more details.

This l2_packet implementation is explicitly for WinPcap and Windows events. l2_packet_pcap.c has support for WinPcap, but it requires polling to receive frames which means relatively long latency for EAPOL RX processing. The implementation here uses a separate thread to allow WinPcap to be receiving all the time to reduce latency for EAPOL receiving from about 100 ms to 3 ms when comparing l2_packet_pcap.c to l2_packet_winpcap.c. Extra sleep of 50 ms is added in to receive thread whenever no EAPOL frames has been received for a while. Whenever an EAPOL handshake is expected, this sleep is removed.

The RX thread receives a frame and signals main thread through Windows event about the availability of a new frame. Processing the received frame is synchronized with pair of Windows events so that no extra buffer or queuing mechanism is needed. This implementation requires Windows specific event loop implementation, i.e., eloop_win.c.

WinPcap has pcap_getevent() that could, in theory at least, be used to implement this kind of waiting with a simpler single-thread design. However, that event handle is not really signaled immediately when receiving each frame, so it does not really work for this kind of use.

Definition in file l2_packet_winpcap.c.

---

Function Documentation

void l2_packet_deinit (  struct l2_packet_data *  l2  )

Deinitialize l2_packet interface. Parameters: l2  Pointer to internal l2_packet data from l2_packet_init() Definition at line 280 of file l2_packet_winpcap.c. Here is the call graph for this function:

int l2_packet_get_ip_addr (  struct l2_packet_data *  l2, char *  buf, size_t  len )

Get the current IP address from the interface. Parameters: l2  Pointer to internal l2_packet data from l2_packet_init() buf  Buffer for the IP address in text format len  Maximum buffer length Returns: 0 on success, -1 on failure This function can be used to get the current IP address from the interface bound to the l2_packet. This is mainly for status information and the IP address will be stored as an ASCII string. This function is not essential for wpa_supplicant operation, so full implementation is not required. l2_packet implementation will need to define the function, but it can return -1 if the IP address information is not available. Definition at line 302 of file l2_packet_winpcap.c. Here is the call graph for this function:

int l2_packet_get_own_addr (  struct l2_packet_data *  l2, u8 *  addr )

Get own layer 2 address. Parameters: l2  Pointer to internal l2_packet data from l2_packet_init() addr  Buffer for the own address (6 bytes) Returns: 0 on success, -1 on failure Definition at line 72 of file l2_packet_winpcap.c.

struct l2_packet_data* l2_packet_init (  const char *  ifname, const u8 *  own_addr, unsigned short  protocol, void(*)(void *ctx, const u8 *src_addr, const u8 *buf, size_t len)  rx_callback, void *  rx_callback_ctx, int  l2_hdr )

Initialize l2_packet interface. Parameters: ifname  Interface name own_addr  Optional own MAC address if available from driver interface or NULL if not available protocol  Ethernet protocol number in host byte order rx_callback  Callback function that will be called for each received packet rx_callback_ctx  Callback data (ctx) for calls to rx_callback() l2_hdr  1 = include layer 2 header, 0 = do not include header Returns: Pointer to internal data or NULL on failure rx_callback function will be called with src_addr pointing to the source address (MAC address) of the the packet. If l2_hdr is set to 0, buf points to len bytes of the payload after the layer 2 header and similarly, TX buffers start with payload. This behavior can be changed by setting l2_hdr=1 to include the layer 2 header in the data buffer. Definition at line 205 of file l2_packet_winpcap.c. Here is the call graph for this function:

void l2_packet_notify_auth_start (  struct l2_packet_data *  l2  )

Notify l2_packet about start of authentication. Parameters: l2  Pointer to internal l2_packet data from l2_packet_init() This function is called when authentication is expected to start, e.g., when association has been completed, in order to prepare l2_packet implementation for EAPOL frames. This function is used mainly if the l2_packet code needs to do polling in which case it can increasing polling frequency. This can also be an empty function if the l2_packet implementation does not benefit from knowing about the starting authentication. Definition at line 338 of file l2_packet_winpcap.c.

int l2_packet_send (  struct l2_packet_data *  l2, const u8 *  dst_addr, u16  proto, const u8 *  buf, size_t  len )

Send a packet. Parameters: l2  Pointer to internal l2_packet data from l2_packet_init() dst_addr  Destination address for the packet (only used if l2_hdr == 0) proto  Protocol/ethertype for the packet in host byte order (only used if l2_hdr == 0) buf  Packet contents to be sent; including layer 2 header if l2_hdr was set to 1 in l2_packet_init() call. Otherwise, only the payload of the packet is included. len  Length of the buffer (including l2 header only if l2_hdr == 1) Returns: >=0 on success, <0 on failure Definition at line 79 of file l2_packet_winpcap.c.

---