/*
   * This file define the new driver API for Wireless Extensions
   *
   * Version :	8	16.3.07
   *
   * Authors :	Jean Tourrilhes - HPL - <jt@hpl.hp.com>
   * Copyright (c) 2001-2007 Jean Tourrilhes, All Rights Reserved.
   */
  
  #ifndef _IW_HANDLER_H
  #define _IW_HANDLER_H
  
  /************************** DOCUMENTATION **************************/
  /*
   * Initial driver API (1996 -> onward) :
   * -----------------------------------
   * The initial API just sends the IOCTL request received from user space
   * to the driver (via the driver ioctl handler). The driver has to
   * handle all the rest...
   *
   * The initial API also defines a specific handler in struct net_device
   * to handle wireless statistics.
   *
   * The initial APIs served us well and has proven a reasonably good design.
   * However, there is a few shortcommings :
   *	o No events, everything is a request to the driver.
   *	o Large ioctl function in driver with gigantic switch statement
   *	  (i.e. spaghetti code).
   *	o Driver has to mess up with copy_to/from_user, and in many cases
   *	  does it unproperly. Common mistakes are :
   *		* buffer overflows (no checks or off by one checks)
   *		* call copy_to/from_user with irq disabled
   *	o The user space interface is tied to ioctl because of the use
   *	  copy_to/from_user.
   *
   * New driver API (2002 -> onward) :
   * -------------------------------
   * The new driver API is just a bunch of standard functions (handlers),
   * each handling a specific Wireless Extension. The driver just export
   * the list of handler it supports, and those will be called apropriately.
   *
   * I tried to keep the main advantage of the previous API (simplicity,
   * efficiency and light weight), and also I provide a good dose of backward
   * compatibility (most structures are the same, driver can use both API
   * simultaneously, ...).
   * Hopefully, I've also addressed the shortcomming of the initial API.
   *
   * The advantage of the new API are :
   *	o Handling of Extensions in driver broken in small contained functions
   *	o Tighter checks of ioctl before calling the driver
   *	o Flexible commit strategy (at least, the start of it)
   *	o Backward compatibility (can be mixed with old API)
   *	o Driver doesn't have to worry about memory and user-space issues
   * The last point is important for the following reasons :
   *	o You are now able to call the new driver API from any API you
   *		want (including from within other parts of the kernel).
   *	o Common mistakes are avoided (buffer overflow, user space copy
   *		with irq disabled and so on).
   *
   * The Drawback of the new API are :
   *	o bloat (especially kernel)
   *	o need to migrate existing drivers to new API
   * My initial testing shows that the new API adds around 3kB to the kernel
   * and save between 0 and 5kB from a typical driver.
   * Also, as all structures and data types are unchanged, the migration is
   * quite straightforward (but tedious).
   *
   * ---
   *
   * The new driver API is defined below in this file. User space should
   * not be aware of what's happening down there...
   *
   * A new kernel wrapper is in charge of validating the IOCTLs and calling
   * the appropriate driver handler. This is implemented in :
   *	# net/core/wireless.c
   *
   * The driver export the list of handlers in :
   *	# include/linux/netdevice.h (one place)
   *
   * The new driver API is available for WIRELESS_EXT >= 13.
   * Good luck with migration to the new API ;-)
   */
  
  /* ---------------------- THE IMPLEMENTATION ---------------------- */
  /*
   * Some of the choice I've made are pretty controversials. Defining an
   * API is very much weighting compromises. This goes into some of the
   * details and the thinking behind the implementation.
   *
   * Implementation goals :
   * --------------------
   * The implementation goals were as follow :
   *	o Obvious : you should not need a PhD to understand what's happening,
   *		the benefit is easier maintenance.
   *	o Flexible : it should accommodate a wide variety of driver
   *		implementations and be as flexible as the old API.
   *	o Lean : it should be efficient memory wise to minimise the impact
   *		on kernel footprint.
   *	o Transparent to user space : the large number of user space
   *		applications that use Wireless Extensions should not need
   *		any modifications.
   *
   * Array of functions versus Struct of functions
   * ---------------------------------------------
   * 1) Having an array of functions allow the kernel code to access the
   * handler in a single lookup, which is much more efficient (think hash
   * table here).
   * 2) The only drawback is that driver writer may put their handler in
   * the wrong slot. This is trivial to test (I set the frequency, the
   * bitrate changes). Once the handler is in the proper slot, it will be
   * there forever, because the array is only extended at the end.
   * 3) Backward/forward compatibility : adding new handler just require
   * extending the array, so you can put newer driver in older kernel
   * without having to patch the kernel code (and vice versa).
   *
   * All handler are of the same generic type
   * ----------------------------------------
   * That's a feature !!!
   * 1) Having a generic handler allow to have generic code, which is more
   * efficient. If each of the handler was individually typed I would need
   * to add a big switch in the kernel (== more bloat). This solution is
   * more scalable, adding new Wireless Extensions doesn't add new code.
   * 2) You can use the same handler in different slots of the array. For
   * hardware, it may be more efficient or logical to handle multiple
   * Wireless Extensions with a single function, and the API allow you to
   * do that. (An example would be a single record on the card to control
   * both bitrate and frequency, the handler would read the old record,
   * modify it according to info->cmd and rewrite it).
   *
   * Functions prototype uses union iwreq_data
   * -----------------------------------------
   * Some would have preferred functions defined this way :
   *	static int mydriver_ioctl_setrate(struct net_device *dev, 
   *					  long rate, int auto)
   * 1) The kernel code doesn't "validate" the content of iwreq_data, and
   * can't do it (different hardware may have different notion of what a
   * valid frequency is), so we don't pretend that we do it.
   * 2) The above form is not extendable. If I want to add a flag (for
   * example to distinguish setting max rate and basic rate), I would
   * break the prototype. Using iwreq_data is more flexible.
   * 3) Also, the above form is not generic (see above).
   * 4) I don't expect driver developper using the wrong field of the
   * union (Doh !), so static typechecking doesn't add much value.
   * 5) Lastly, you can skip the union by doing :
   *	static int mydriver_ioctl_setrate(struct net_device *dev,
   *					  struct iw_request_info *info,
   *					  struct iw_param *rrq,
   *					  char *extra)
   * And then adding the handler in the array like this :
   *        (iw_handler) mydriver_ioctl_setrate,             // SIOCSIWRATE
   *
   * Using functions and not a registry
   * ----------------------------------
   * Another implementation option would have been for every instance to
   * define a registry (a struct containing all the Wireless Extensions)
   * and only have a function to commit the registry to the hardware.
   * 1) This approach can be emulated by the current code, but not
   * vice versa.
   * 2) Some drivers don't keep any configuration in the driver, for them
   * adding such a registry would be a significant bloat.
   * 3) The code to translate from Wireless Extension to native format is
   * needed anyway, so it would not reduce significantely the amount of code.
   * 4) The current approach only selectively translate Wireless Extensions
   * to native format and only selectively set, whereas the registry approach
   * would require to translate all WE and set all parameters for any single
   * change.
   * 5) For many Wireless Extensions, the GET operation return the current
   * dynamic value, not the value that was set.
   *
   * This header is <net/iw_handler.h>
   * ---------------------------------
   * 1) This header is kernel space only and should not be exported to
   * user space. Headers in "include/linux/" are exported, headers in
   * "include/net/" are not.
   *
   * Mixed 32/64 bit issues
   * ----------------------
   * The Wireless Extensions are designed to be 64 bit clean, by using only
   * datatypes with explicit storage size.
   * There are some issues related to kernel and user space using different
   * memory model, and in particular 64bit kernel with 32bit user space.
   * The problem is related to struct iw_point, that contains a pointer
   * that *may* need to be translated.
   * This is quite messy. The new API doesn't solve this problem (it can't),
   * but is a step in the right direction :
   * 1) Meta data about each ioctl is easily available, so we know what type
   * of translation is needed.
   * 2) The move of data between kernel and user space is only done in a single
   * place in the kernel, so adding specific hooks in there is possible.
   * 3) In the long term, it allows to move away from using ioctl as the
   * user space API.
   *
   * So many comments and so few code
   * --------------------------------
   * That's a feature. Comments won't bloat the resulting kernel binary.
   */
  
  /***************************** INCLUDES *****************************/
  
  #include <linux/wireless.h>		/* IOCTL user space API */
  #include <linux/if_ether.h>
  
  /***************************** VERSION *****************************/
  /*
   * This constant is used to know which version of the driver API is
   * available. Hopefully, this will be pretty stable and no changes
   * will be needed...
   * I just plan to increment with each new version.
   */
  #define IW_HANDLER_VERSION	8
  
  /*
   * Changes :
   *
   * V2 to V3
   * --------
   *	- Move event definition in <linux/wireless.h>
   *	- Add Wireless Event support :
   *		o wireless_send_event() prototype
   *		o iwe_stream_add_event/point() inline functions
   * V3 to V4
   * --------
   *	- Reshuffle IW_HEADER_TYPE_XXX to map IW_PRIV_TYPE_XXX changes
   *
   * V4 to V5
   * --------
   *	- Add new spy support : struct iw_spy_data & prototypes
   *
   * V5 to V6
   * --------
   *	- Change the way we get to spy_data method for added safety
   *	- Remove spy #ifdef, they are always on -> cleaner code
   *	- Add IW_DESCR_FLAG_NOMAX flag for very large requests
   *	- Start migrating get_wireless_stats to struct iw_handler_def
   *
   * V6 to V7
   * --------
   *	- Add struct ieee80211_device pointer in struct iw_public_data
   *	- Remove (struct iw_point *)->pointer from events and streams
   *	- Remove spy_offset from struct iw_handler_def
   *	- Add "check" version of event macros for ieee802.11 stack
   *
   * V7 to V8
   * ----------
   *	- Prevent leaking of kernel space in stream on 64 bits.
   */
  
  /**************************** CONSTANTS ****************************/
  
  /* Enhanced spy support available */
  #define IW_WIRELESS_SPY
  #define IW_WIRELESS_THRSPY
  
  /* Special error message for the driver to indicate that we
   * should do a commit after return from the iw_handler */
  #define EIWCOMMIT	EINPROGRESS
  
  /* Flags available in struct iw_request_info */
  #define IW_REQUEST_FLAG_COMPAT	0x0001	/* Compat ioctl call */
  
  /* Type of headers we know about (basically union iwreq_data) */
  #define IW_HEADER_TYPE_NULL	0	/* Not available */
  #define IW_HEADER_TYPE_CHAR	2	/* char [IFNAMSIZ] */
  #define IW_HEADER_TYPE_UINT	4	/* __u32 */
  #define IW_HEADER_TYPE_FREQ	5	/* struct iw_freq */
  #define IW_HEADER_TYPE_ADDR	6	/* struct sockaddr */
  #define IW_HEADER_TYPE_POINT	8	/* struct iw_point */
  #define IW_HEADER_TYPE_PARAM	9	/* struct iw_param */
  #define IW_HEADER_TYPE_QUAL	10	/* struct iw_quality */
  
  /* Handling flags */
  /* Most are not implemented. I just use them as a reminder of some
   * cool features we might need one day ;-) */
  #define IW_DESCR_FLAG_NONE	0x0000	/* Obvious */
  /* Wrapper level flags */
  #define IW_DESCR_FLAG_DUMP	0x0001	/* Not part of the dump command */
  #define IW_DESCR_FLAG_EVENT	0x0002	/* Generate an event on SET */
  #define IW_DESCR_FLAG_RESTRICT	0x0004	/* GET : request is ROOT only */
  				/* SET : Omit payload from generated iwevent */
  #define IW_DESCR_FLAG_NOMAX	0x0008	/* GET : no limit on request size */
  /* Driver level flags */
  #define IW_DESCR_FLAG_WAIT	0x0100	/* Wait for driver event */
  
  /****************************** TYPES ******************************/
  
  /* ----------------------- WIRELESS HANDLER ----------------------- */
  /*
   * A wireless handler is just a standard function, that looks like the
   * ioctl handler.
   * We also define there how a handler list look like... As the Wireless
   * Extension space is quite dense, we use a simple array, which is faster
   * (that's the perfect hash table ;-).
   */
  
  /*
   * Meta data about the request passed to the iw_handler.
   * Most handlers can safely ignore what's in there.
   * The 'cmd' field might come handy if you want to use the same handler
   * for multiple command...
   * This struct is also my long term insurance. I can add new fields here
   * without breaking the prototype of iw_handler...
   */
  struct iw_request_info {
  	__u16		cmd;		/* Wireless Extension command */
  	__u16		flags;		/* More to come ;-) */
  };
  
  struct net_device;
  
  /*
   * This is how a function handling a Wireless Extension should look
   * like (both get and set, standard and private).
   */
  typedef int (*iw_handler)(struct net_device *dev, struct iw_request_info *info,
  			  union iwreq_data *wrqu, char *extra);
  
  /*
   * This define all the handler that the driver export.
   * As you need only one per driver type, please use a static const
   * shared by all driver instances... Same for the members...
   * This will be linked from net_device in <linux/netdevice.h>
   */
  struct iw_handler_def {
  
  	/* Array of handlers for standard ioctls
  	 * We will call dev->wireless_handlers->standard[ioctl - SIOCIWFIRST]
  	 */
  	const iw_handler *	standard;
  	/* Number of handlers defined (more precisely, index of the
  	 * last defined handler + 1) */
  	__u16			num_standard;
  
  #ifdef CONFIG_WEXT_PRIV
  	__u16			num_private;
  	/* Number of private arg description */
  	__u16			num_private_args;
  	/* Array of handlers for private ioctls
  	 * Will call dev->wireless_handlers->private[ioctl - SIOCIWFIRSTPRIV]
  	 */
  	const iw_handler *	private;
  
  	/* Arguments of private handler. This one is just a list, so you
  	 * can put it in any order you want and should not leave holes...
  	 * We will automatically export that to user space... */
  	const struct iw_priv_args *	private_args;
  #endif
  
  	/* New location of get_wireless_stats, to de-bloat struct net_device.
  	 * The old pointer in struct net_device will be gradually phased
  	 * out, and drivers are encouraged to use this one... */
  	struct iw_statistics*	(*get_wireless_stats)(struct net_device *dev);
  };
  
  /* ---------------------- IOCTL DESCRIPTION ---------------------- */
  /*
   * One of the main goal of the new interface is to deal entirely with
   * user space/kernel space memory move.
   * For that, we need to know :
   *	o if iwreq is a pointer or contain the full data
   *	o what is the size of the data to copy
   *
   * For private IOCTLs, we use the same rules as used by iwpriv and
   * defined in struct iw_priv_args.
   *
   * For standard IOCTLs, things are quite different and we need to
   * use the stuctures below. Actually, this struct is also more
   * efficient, but that's another story...
   */
  
  /*
   * Describe how a standard IOCTL looks like.
   */
  struct iw_ioctl_description {
  	__u8	header_type;		/* NULL, iw_point or other */
  	__u8	token_type;		/* Future */
  	__u16	token_size;		/* Granularity of payload */
  	__u16	min_tokens;		/* Min acceptable token number */
  	__u16	max_tokens;		/* Max acceptable token number */
  	__u32	flags;			/* Special handling of the request */
  };
  
  /* Need to think of short header translation table. Later. */
  
  /* --------------------- ENHANCED SPY SUPPORT --------------------- */
  /*
   * In the old days, the driver was handling spy support all by itself.
   * Now, the driver can delegate this task to Wireless Extensions.
   * It needs to include this struct in its private part and use the
   * standard spy iw_handler.
   */
  
  /*
   * Instance specific spy data, i.e. addresses spied and quality for them.
   */
  struct iw_spy_data {
  	/* --- Standard spy support --- */
  	int			spy_number;
  	u_char			spy_address[IW_MAX_SPY][ETH_ALEN];
  	struct iw_quality	spy_stat[IW_MAX_SPY];
  	/* --- Enhanced spy support (event) */
  	struct iw_quality	spy_thr_low;	/* Low threshold */
  	struct iw_quality	spy_thr_high;	/* High threshold */
  	u_char			spy_thr_under[IW_MAX_SPY];
  };
  
  /* --------------------- DEVICE WIRELESS DATA --------------------- */
  /*
   * This is all the wireless data specific to a device instance that
   * is managed by the core of Wireless Extensions or the 802.11 layer.
   * We only keep pointer to those structures, so that a driver is free
   * to share them between instances.
   * This structure should be initialised before registering the device.
   * Access to this data follow the same rules as any other struct net_device
   * data (i.e. valid as long as struct net_device exist, same locking rules).
   */
  /* Forward declaration */
  struct libipw_device;
  /* The struct */
  struct iw_public_data {
  	/* Driver enhanced spy support */
  	struct iw_spy_data *		spy_data;
  	/* Legacy structure managed by the ipw2x00-specific IEEE 802.11 layer */
  	struct libipw_device *		libipw;
  };
  
  /**************************** PROTOTYPES ****************************/
  /*
   * Functions part of the Wireless Extensions (defined in net/core/wireless.c).
   * Those may be called only within the kernel.
   */
  
  /* First : function strictly used inside the kernel */
  
  /* Handle /proc/net/wireless, called in net/code/dev.c */
  int dev_get_wireless_info(char *buffer, char **start, off_t offset, int length);
  
  /* Second : functions that may be called by driver modules */
  
  /* Send a single event to user space */
  void wireless_send_event(struct net_device *dev, unsigned int cmd,
  			 union iwreq_data *wrqu, const char *extra);
  
  /* We may need a function to send a stream of events to user space.
   * More on that later... */
  
  /* Standard handler for SIOCSIWSPY */
  int iw_handler_set_spy(struct net_device *dev, struct iw_request_info *info,
  		       union iwreq_data *wrqu, char *extra);
  /* Standard handler for SIOCGIWSPY */
  int iw_handler_get_spy(struct net_device *dev, struct iw_request_info *info,
  		       union iwreq_data *wrqu, char *extra);
  /* Standard handler for SIOCSIWTHRSPY */
  int iw_handler_set_thrspy(struct net_device *dev, struct iw_request_info *info,
  			  union iwreq_data *wrqu, char *extra);
  /* Standard handler for SIOCGIWTHRSPY */
  int iw_handler_get_thrspy(struct net_device *dev, struct iw_request_info *info,
  			  union iwreq_data *wrqu, char *extra);
  /* Driver call to update spy records */
  void wireless_spy_update(struct net_device *dev, unsigned char *address,
  			 struct iw_quality *wstats);
  
  /************************* INLINE FUNTIONS *************************/
  /*
   * Function that are so simple that it's more efficient inlining them
   */
  
  static inline int iwe_stream_lcp_len(struct iw_request_info *info)
  {
  #ifdef CONFIG_COMPAT
  	if (info->flags & IW_REQUEST_FLAG_COMPAT)
  		return IW_EV_COMPAT_LCP_LEN;
  #endif
  	return IW_EV_LCP_LEN;
  }
  
  static inline int iwe_stream_point_len(struct iw_request_info *info)
  {
  #ifdef CONFIG_COMPAT
  	if (info->flags & IW_REQUEST_FLAG_COMPAT)
  		return IW_EV_COMPAT_POINT_LEN;
  #endif
  	return IW_EV_POINT_LEN;
  }
  
  static inline int iwe_stream_event_len_adjust(struct iw_request_info *info,
  					      int event_len)
  {
  #ifdef CONFIG_COMPAT
  	if (info->flags & IW_REQUEST_FLAG_COMPAT) {
  		event_len -= IW_EV_LCP_LEN;
  		event_len += IW_EV_COMPAT_LCP_LEN;
  	}
  #endif
  
  	return event_len;
  }
  
  /*------------------------------------------------------------------*/
  /*
   * Wrapper to add an Wireless Event to a stream of events.
   */
  static inline char *
  iwe_stream_add_event(struct iw_request_info *info, char *stream, char *ends,
  		     struct iw_event *iwe, int event_len)
  {
  	int lcp_len = iwe_stream_lcp_len(info);
  
  	event_len = iwe_stream_event_len_adjust(info, event_len);
  
  	/* Check if it's possible */
  	if(likely((stream + event_len) < ends)) {
  		iwe->len = event_len;
  		/* Beware of alignement issues on 64 bits */
  		memcpy(stream, (char *) iwe, IW_EV_LCP_PK_LEN);
  		memcpy(stream + lcp_len, &iwe->u,
  		       event_len - lcp_len);
  		stream += event_len;
  	}
  	return stream;
  }
  
  /*------------------------------------------------------------------*/
  /*
   * Wrapper to add an short Wireless Event containing a pointer to a
   * stream of events.
   */
  static inline char *
  iwe_stream_add_point(struct iw_request_info *info, char *stream, char *ends,
  		     struct iw_event *iwe, char *extra)
  {
  	int event_len = iwe_stream_point_len(info) + iwe->u.data.length;
  	int point_len = iwe_stream_point_len(info);
  	int lcp_len   = iwe_stream_lcp_len(info);
  
  	/* Check if it's possible */
  	if(likely((stream + event_len) < ends)) {
  		iwe->len = event_len;
  		memcpy(stream, (char *) iwe, IW_EV_LCP_PK_LEN);
  		memcpy(stream + lcp_len,
  		       ((char *) &iwe->u) + IW_EV_POINT_OFF,
  		       IW_EV_POINT_PK_LEN - IW_EV_LCP_PK_LEN);
  		memcpy(stream + point_len, extra, iwe->u.data.length);
  		stream += event_len;
  	}
  	return stream;
  }
  
  /*------------------------------------------------------------------*/
  /*
   * Wrapper to add a value to a Wireless Event in a stream of events.
   * Be careful, this one is tricky to use properly :
   * At the first run, you need to have (value = event + IW_EV_LCP_LEN).
   */
  static inline char *
  iwe_stream_add_value(struct iw_request_info *info, char *event, char *value,
  		     char *ends, struct iw_event *iwe, int event_len)
  {
  	int lcp_len = iwe_stream_lcp_len(info);
  
  	/* Don't duplicate LCP */
  	event_len -= IW_EV_LCP_LEN;
  
  	/* Check if it's possible */
  	if(likely((value + event_len) < ends)) {
  		/* Add new value */
  		memcpy(value, &iwe->u, event_len);
  		value += event_len;
  		/* Patch LCP */
  		iwe->len = value - event;
  		memcpy(event, (char *) iwe, lcp_len);
  	}
  	return value;
  }
  
  #endif	/* _IW_HANDLER_H */