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Diffstat (limited to 'include/net/iw_handler.h')
| -rw-r--r-- | include/net/iw_handler.h | 540 |
1 files changed, 540 insertions, 0 deletions
diff --git a/include/net/iw_handler.h b/include/net/iw_handler.h new file mode 100644 index 0000000..44edd48 --- /dev/null +++ b/include/net/iw_handler.h @@ -0,0 +1,540 @@ +/* + * This file define the new driver API for Wireless Extensions + * + * Version : 6 21.6.04 + * + * Authors : Jean Tourrilhes - HPL - <jt@hpl.hp.com> + * Copyright (c) 2001-2004 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 maintainance. + * 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 prefered 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 6 + +/* + * 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 + */ + +/**************************** 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_NONE 0x0000 /* No flag so far */ + +/* 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 +{ + /* Number of handlers defined (more precisely, index of the + * last defined handler + 1) */ + __u16 num_standard; + __u16 num_private; + /* Number of private arg description */ + __u16 num_private_args; + + /* Array of handlers for standard ioctls + * We will call dev->wireless_handlers->standard[ioctl - SIOCSIWNAME] + */ + const iw_handler * standard; + + /* 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; + + /* This field will be *removed* in the next version of WE */ + long spy_offset; /* DO NOT USE */ + + /* 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. + * 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). + */ +struct iw_public_data { + /* Driver enhanced spy support */ + struct iw_spy_data * spy_data; +}; + +/**************************** 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 */ +extern int dev_get_wireless_info(char * buffer, char **start, off_t offset, + int length); + +/* Handle IOCTLs, called in net/code/dev.c */ +extern int wireless_process_ioctl(struct ifreq *ifr, unsigned int cmd); + +/* Second : functions that may be called by driver modules */ + +/* Send a single event to user space */ +extern void wireless_send_event(struct net_device * dev, + unsigned int cmd, + union iwreq_data * wrqu, + char * extra); + +/* We may need a function to send a stream of events to user space. + * More on that later... */ + +/* Standard handler for SIOCSIWSPY */ +extern int iw_handler_set_spy(struct net_device * dev, + struct iw_request_info * info, + union iwreq_data * wrqu, + char * extra); +/* Standard handler for SIOCGIWSPY */ +extern int iw_handler_get_spy(struct net_device * dev, + struct iw_request_info * info, + union iwreq_data * wrqu, + char * extra); +/* Standard handler for SIOCSIWTHRSPY */ +extern int iw_handler_set_thrspy(struct net_device * dev, + struct iw_request_info *info, + union iwreq_data * wrqu, + char * extra); +/* Standard handler for SIOCGIWTHRSPY */ +extern 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 */ +extern 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 + */ + +/*------------------------------------------------------------------*/ +/* + * Wrapper to add an Wireless Event to a stream of events. + */ +static inline char * +iwe_stream_add_event(char * stream, /* Stream of events */ + char * ends, /* End of stream */ + struct iw_event *iwe, /* Payload */ + int event_len) /* Real size of payload */ +{ + /* Check if it's possible */ + if((stream + event_len) < ends) { + iwe->len = event_len; + memcpy(stream, (char *) iwe, event_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(char * stream, /* Stream of events */ + char * ends, /* End of stream */ + struct iw_event *iwe, /* Payload */ + char * extra) +{ + int event_len = IW_EV_POINT_LEN + iwe->u.data.length; + /* Check if it's possible */ + if((stream + event_len) < ends) { + iwe->len = event_len; + memcpy(stream, (char *) iwe, IW_EV_POINT_LEN); + memcpy(stream + IW_EV_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(char * event, /* Event in the stream */ + char * value, /* Value in event */ + char * ends, /* End of stream */ + struct iw_event *iwe, /* Payload */ + int event_len) /* Real size of payload */ +{ + /* Don't duplicate LCP */ + event_len -= IW_EV_LCP_LEN; + + /* Check if it's possible */ + if((value + event_len) < ends) { + /* Add new value */ + memcpy(value, (char *) iwe + IW_EV_LCP_LEN, event_len); + value += event_len; + /* Patch LCP */ + iwe->len = value - event; + memcpy(event, (char *) iwe, IW_EV_LCP_LEN); + } + return value; +} + +#endif /* _IW_HANDLER_H */ |