linux/include/net/iw_handler.h
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   1/*
   2 * This file define the new driver API for Wireless Extensions
   3 *
   4 * Version :    8       16.3.07
   5 *
   6 * Authors :    Jean Tourrilhes - HPL - <jt@hpl.hp.com>
   7 * Copyright (c) 2001-2007 Jean Tourrilhes, All Rights Reserved.
   8 */
   9
  10#ifndef _IW_HANDLER_H
  11#define _IW_HANDLER_H
  12
  13/************************** DOCUMENTATION **************************/
  14/*
  15 * Initial driver API (1996 -> onward) :
  16 * -----------------------------------
  17 * The initial API just sends the IOCTL request received from user space
  18 * to the driver (via the driver ioctl handler). The driver has to
  19 * handle all the rest...
  20 *
  21 * The initial API also defines a specific handler in struct net_device
  22 * to handle wireless statistics.
  23 *
  24 * The initial APIs served us well and has proven a reasonably good design.
  25 * However, there is a few shortcommings :
  26 *      o No events, everything is a request to the driver.
  27 *      o Large ioctl function in driver with gigantic switch statement
  28 *        (i.e. spaghetti code).
  29 *      o Driver has to mess up with copy_to/from_user, and in many cases
  30 *        does it unproperly. Common mistakes are :
  31 *              * buffer overflows (no checks or off by one checks)
  32 *              * call copy_to/from_user with irq disabled
  33 *      o The user space interface is tied to ioctl because of the use
  34 *        copy_to/from_user.
  35 *
  36 * New driver API (2002 -> onward) :
  37 * -------------------------------
  38 * The new driver API is just a bunch of standard functions (handlers),
  39 * each handling a specific Wireless Extension. The driver just export
  40 * the list of handler it supports, and those will be called apropriately.
  41 *
  42 * I tried to keep the main advantage of the previous API (simplicity,
  43 * efficiency and light weight), and also I provide a good dose of backward
  44 * compatibility (most structures are the same, driver can use both API
  45 * simultaneously, ...).
  46 * Hopefully, I've also addressed the shortcomming of the initial API.
  47 *
  48 * The advantage of the new API are :
  49 *      o Handling of Extensions in driver broken in small contained functions
  50 *      o Tighter checks of ioctl before calling the driver
  51 *      o Flexible commit strategy (at least, the start of it)
  52 *      o Backward compatibility (can be mixed with old API)
  53 *      o Driver doesn't have to worry about memory and user-space issues
  54 * The last point is important for the following reasons :
  55 *      o You are now able to call the new driver API from any API you
  56 *              want (including from within other parts of the kernel).
  57 *      o Common mistakes are avoided (buffer overflow, user space copy
  58 *              with irq disabled and so on).
  59 *
  60 * The Drawback of the new API are :
  61 *      o bloat (especially kernel)
  62 *      o need to migrate existing drivers to new API
  63 * My initial testing shows that the new API adds around 3kB to the kernel
  64 * and save between 0 and 5kB from a typical driver.
  65 * Also, as all structures and data types are unchanged, the migration is
  66 * quite straightforward (but tedious).
  67 *
  68 * ---
  69 *
  70 * The new driver API is defined below in this file. User space should
  71 * not be aware of what's happening down there...
  72 *
  73 * A new kernel wrapper is in charge of validating the IOCTLs and calling
  74 * the appropriate driver handler. This is implemented in :
  75 *      # net/core/wireless.c
  76 *
  77 * The driver export the list of handlers in :
  78 *      # include/linux/netdevice.h (one place)
  79 *
  80 * The new driver API is available for WIRELESS_EXT >= 13.
  81 * Good luck with migration to the new API ;-)
  82 */
  83
  84/* ---------------------- THE IMPLEMENTATION ---------------------- */
  85/*
  86 * Some of the choice I've made are pretty controversials. Defining an
  87 * API is very much weighting compromises. This goes into some of the
  88 * details and the thinking behind the implementation.
  89 *
  90 * Implementation goals :
  91 * --------------------
  92 * The implementation goals were as follow :
  93 *      o Obvious : you should not need a PhD to understand what's happening,
  94 *              the benefit is easier maintenance.
  95 *      o Flexible : it should accommodate a wide variety of driver
  96 *              implementations and be as flexible as the old API.
  97 *      o Lean : it should be efficient memory wise to minimise the impact
  98 *              on kernel footprint.
  99 *      o Transparent to user space : the large number of user space
 100 *              applications that use Wireless Extensions should not need
 101 *              any modifications.
 102 *
 103 * Array of functions versus Struct of functions
 104 * ---------------------------------------------
 105 * 1) Having an array of functions allow the kernel code to access the
 106 * handler in a single lookup, which is much more efficient (think hash
 107 * table here).
 108 * 2) The only drawback is that driver writer may put their handler in
 109 * the wrong slot. This is trivial to test (I set the frequency, the
 110 * bitrate changes). Once the handler is in the proper slot, it will be
 111 * there forever, because the array is only extended at the end.
 112 * 3) Backward/forward compatibility : adding new handler just require
 113 * extending the array, so you can put newer driver in older kernel
 114 * without having to patch the kernel code (and vice versa).
 115 *
 116 * All handler are of the same generic type
 117 * ----------------------------------------
 118 * That's a feature !!!
 119 * 1) Having a generic handler allow to have generic code, which is more
 120 * efficient. If each of the handler was individually typed I would need
 121 * to add a big switch in the kernel (== more bloat). This solution is
 122 * more scalable, adding new Wireless Extensions doesn't add new code.
 123 * 2) You can use the same handler in different slots of the array. For
 124 * hardware, it may be more efficient or logical to handle multiple
 125 * Wireless Extensions with a single function, and the API allow you to
 126 * do that. (An example would be a single record on the card to control
 127 * both bitrate and frequency, the handler would read the old record,
 128 * modify it according to info->cmd and rewrite it).
 129 *
 130 * Functions prototype uses union iwreq_data
 131 * -----------------------------------------
 132 * Some would have preferred functions defined this way :
 133 *      static int mydriver_ioctl_setrate(struct net_device *dev, 
 134 *                                        long rate, int auto)
 135 * 1) The kernel code doesn't "validate" the content of iwreq_data, and
 136 * can't do it (different hardware may have different notion of what a
 137 * valid frequency is), so we don't pretend that we do it.
 138 * 2) The above form is not extendable. If I want to add a flag (for
 139 * example to distinguish setting max rate and basic rate), I would
 140 * break the prototype. Using iwreq_data is more flexible.
 141 * 3) Also, the above form is not generic (see above).
 142 * 4) I don't expect driver developper using the wrong field of the
 143 * union (Doh !), so static typechecking doesn't add much value.
 144 * 5) Lastly, you can skip the union by doing :
 145 *      static int mydriver_ioctl_setrate(struct net_device *dev,
 146 *                                        struct iw_request_info *info,
 147 *                                        struct iw_param *rrq,
 148 *                                        char *extra)
 149 * And then adding the handler in the array like this :
 150 *        (iw_handler) mydriver_ioctl_setrate,             // SIOCSIWRATE
 151 *
 152 * Using functions and not a registry
 153 * ----------------------------------
 154 * Another implementation option would have been for every instance to
 155 * define a registry (a struct containing all the Wireless Extensions)
 156 * and only have a function to commit the registry to the hardware.
 157 * 1) This approach can be emulated by the current code, but not
 158 * vice versa.
 159 * 2) Some drivers don't keep any configuration in the driver, for them
 160 * adding such a registry would be a significant bloat.
 161 * 3) The code to translate from Wireless Extension to native format is
 162 * needed anyway, so it would not reduce significantely the amount of code.
 163 * 4) The current approach only selectively translate Wireless Extensions
 164 * to native format and only selectively set, whereas the registry approach
 165 * would require to translate all WE and set all parameters for any single
 166 * change.
 167 * 5) For many Wireless Extensions, the GET operation return the current
 168 * dynamic value, not the value that was set.
 169 *
 170 * This header is <net/iw_handler.h>
 171 * ---------------------------------
 172 * 1) This header is kernel space only and should not be exported to
 173 * user space. Headers in "include/linux/" are exported, headers in
 174 * "include/net/" are not.
 175 *
 176 * Mixed 32/64 bit issues
 177 * ----------------------
 178 * The Wireless Extensions are designed to be 64 bit clean, by using only
 179 * datatypes with explicit storage size.
 180 * There are some issues related to kernel and user space using different
 181 * memory model, and in particular 64bit kernel with 32bit user space.
 182 * The problem is related to struct iw_point, that contains a pointer
 183 * that *may* need to be translated.
 184 * This is quite messy. The new API doesn't solve this problem (it can't),
 185 * but is a step in the right direction :
 186 * 1) Meta data about each ioctl is easily available, so we know what type
 187 * of translation is needed.
 188 * 2) The move of data between kernel and user space is only done in a single
 189 * place in the kernel, so adding specific hooks in there is possible.
 190 * 3) In the long term, it allows to move away from using ioctl as the
 191 * user space API.
 192 *
 193 * So many comments and so few code
 194 * --------------------------------
 195 * That's a feature. Comments won't bloat the resulting kernel binary.
 196 */
 197
 198/***************************** INCLUDES *****************************/
 199
 200#include <linux/wireless.h>             /* IOCTL user space API */
 201#include <linux/if_ether.h>
 202
 203/***************************** VERSION *****************************/
 204/*
 205 * This constant is used to know which version of the driver API is
 206 * available. Hopefully, this will be pretty stable and no changes
 207 * will be needed...
 208 * I just plan to increment with each new version.
 209 */
 210#define IW_HANDLER_VERSION      8
 211
 212/*
 213 * Changes :
 214 *
 215 * V2 to V3
 216 * --------
 217 *      - Move event definition in <linux/wireless.h>
 218 *      - Add Wireless Event support :
 219 *              o wireless_send_event() prototype
 220 *              o iwe_stream_add_event/point() inline functions
 221 * V3 to V4
 222 * --------
 223 *      - Reshuffle IW_HEADER_TYPE_XXX to map IW_PRIV_TYPE_XXX changes
 224 *
 225 * V4 to V5
 226 * --------
 227 *      - Add new spy support : struct iw_spy_data & prototypes
 228 *
 229 * V5 to V6
 230 * --------
 231 *      - Change the way we get to spy_data method for added safety
 232 *      - Remove spy #ifdef, they are always on -> cleaner code
 233 *      - Add IW_DESCR_FLAG_NOMAX flag for very large requests
 234 *      - Start migrating get_wireless_stats to struct iw_handler_def
 235 *
 236 * V6 to V7
 237 * --------
 238 *      - Add struct ieee80211_device pointer in struct iw_public_data
 239 *      - Remove (struct iw_point *)->pointer from events and streams
 240 *      - Remove spy_offset from struct iw_handler_def
 241 *      - Add "check" version of event macros for ieee802.11 stack
 242 *
 243 * V7 to V8
 244 * ----------
 245 *      - Prevent leaking of kernel space in stream on 64 bits.
 246 */
 247
 248/**************************** CONSTANTS ****************************/
 249
 250/* Enhanced spy support available */
 251#define IW_WIRELESS_SPY
 252#define IW_WIRELESS_THRSPY
 253
 254/* Special error message for the driver to indicate that we
 255 * should do a commit after return from the iw_handler */
 256#define EIWCOMMIT       EINPROGRESS
 257
 258/* Flags available in struct iw_request_info */
 259#define IW_REQUEST_FLAG_COMPAT  0x0001  /* Compat ioctl call */
 260
 261/* Type of headers we know about (basically union iwreq_data) */
 262#define IW_HEADER_TYPE_NULL     0       /* Not available */
 263#define IW_HEADER_TYPE_CHAR     2       /* char [IFNAMSIZ] */
 264#define IW_HEADER_TYPE_UINT     4       /* __u32 */
 265#define IW_HEADER_TYPE_FREQ     5       /* struct iw_freq */
 266#define IW_HEADER_TYPE_ADDR     6       /* struct sockaddr */
 267#define IW_HEADER_TYPE_POINT    8       /* struct iw_point */
 268#define IW_HEADER_TYPE_PARAM    9       /* struct iw_param */
 269#define IW_HEADER_TYPE_QUAL     10      /* struct iw_quality */
 270
 271/* Handling flags */
 272/* Most are not implemented. I just use them as a reminder of some
 273 * cool features we might need one day ;-) */
 274#define IW_DESCR_FLAG_NONE      0x0000  /* Obvious */
 275/* Wrapper level flags */
 276#define IW_DESCR_FLAG_DUMP      0x0001  /* Not part of the dump command */
 277#define IW_DESCR_FLAG_EVENT     0x0002  /* Generate an event on SET */
 278#define IW_DESCR_FLAG_RESTRICT  0x0004  /* GET : request is ROOT only */
 279                                /* SET : Omit payload from generated iwevent */
 280#define IW_DESCR_FLAG_NOMAX     0x0008  /* GET : no limit on request size */
 281/* Driver level flags */
 282#define IW_DESCR_FLAG_WAIT      0x0100  /* Wait for driver event */
 283
 284/****************************** TYPES ******************************/
 285
 286/* ----------------------- WIRELESS HANDLER ----------------------- */
 287/*
 288 * A wireless handler is just a standard function, that looks like the
 289 * ioctl handler.
 290 * We also define there how a handler list look like... As the Wireless
 291 * Extension space is quite dense, we use a simple array, which is faster
 292 * (that's the perfect hash table ;-).
 293 */
 294
 295/*
 296 * Meta data about the request passed to the iw_handler.
 297 * Most handlers can safely ignore what's in there.
 298 * The 'cmd' field might come handy if you want to use the same handler
 299 * for multiple command...
 300 * This struct is also my long term insurance. I can add new fields here
 301 * without breaking the prototype of iw_handler...
 302 */
 303struct iw_request_info {
 304        __u16           cmd;            /* Wireless Extension command */
 305        __u16           flags;          /* More to come ;-) */
 306};
 307
 308struct net_device;
 309
 310/*
 311 * This is how a function handling a Wireless Extension should look
 312 * like (both get and set, standard and private).
 313 */
 314typedef int (*iw_handler)(struct net_device *dev, struct iw_request_info *info,
 315                          union iwreq_data *wrqu, char *extra);
 316
 317/*
 318 * This define all the handler that the driver export.
 319 * As you need only one per driver type, please use a static const
 320 * shared by all driver instances... Same for the members...
 321 * This will be linked from net_device in <linux/netdevice.h>
 322 */
 323struct iw_handler_def {
 324
 325        /* Array of handlers for standard ioctls
 326         * We will call dev->wireless_handlers->standard[ioctl - SIOCIWFIRST]
 327         */
 328        const iw_handler *      standard;
 329        /* Number of handlers defined (more precisely, index of the
 330         * last defined handler + 1) */
 331        __u16                   num_standard;
 332
 333#ifdef CONFIG_WEXT_PRIV
 334        __u16                   num_private;
 335        /* Number of private arg description */
 336        __u16                   num_private_args;
 337        /* Array of handlers for private ioctls
 338         * Will call dev->wireless_handlers->private[ioctl - SIOCIWFIRSTPRIV]
 339         */
 340        const iw_handler *      private;
 341
 342        /* Arguments of private handler. This one is just a list, so you
 343         * can put it in any order you want and should not leave holes...
 344         * We will automatically export that to user space... */
 345        const struct iw_priv_args *     private_args;
 346#endif
 347
 348        /* New location of get_wireless_stats, to de-bloat struct net_device.
 349         * The old pointer in struct net_device will be gradually phased
 350         * out, and drivers are encouraged to use this one... */
 351        struct iw_statistics*   (*get_wireless_stats)(struct net_device *dev);
 352};
 353
 354/* ---------------------- IOCTL DESCRIPTION ---------------------- */
 355/*
 356 * One of the main goal of the new interface is to deal entirely with
 357 * user space/kernel space memory move.
 358 * For that, we need to know :
 359 *      o if iwreq is a pointer or contain the full data
 360 *      o what is the size of the data to copy
 361 *
 362 * For private IOCTLs, we use the same rules as used by iwpriv and
 363 * defined in struct iw_priv_args.
 364 *
 365 * For standard IOCTLs, things are quite different and we need to
 366 * use the stuctures below. Actually, this struct is also more
 367 * efficient, but that's another story...
 368 */
 369
 370/*
 371 * Describe how a standard IOCTL looks like.
 372 */
 373struct iw_ioctl_description {
 374        __u8    header_type;            /* NULL, iw_point or other */
 375        __u8    token_type;             /* Future */
 376        __u16   token_size;             /* Granularity of payload */
 377        __u16   min_tokens;             /* Min acceptable token number */
 378        __u16   max_tokens;             /* Max acceptable token number */
 379        __u32   flags;                  /* Special handling of the request */
 380};
 381
 382/* Need to think of short header translation table. Later. */
 383
 384/* --------------------- ENHANCED SPY SUPPORT --------------------- */
 385/*
 386 * In the old days, the driver was handling spy support all by itself.
 387 * Now, the driver can delegate this task to Wireless Extensions.
 388 * It needs to include this struct in its private part and use the
 389 * standard spy iw_handler.
 390 */
 391
 392/*
 393 * Instance specific spy data, i.e. addresses spied and quality for them.
 394 */
 395struct iw_spy_data {
 396        /* --- Standard spy support --- */
 397        int                     spy_number;
 398        u_char                  spy_address[IW_MAX_SPY][ETH_ALEN];
 399        struct iw_quality       spy_stat[IW_MAX_SPY];
 400        /* --- Enhanced spy support (event) */
 401        struct iw_quality       spy_thr_low;    /* Low threshold */
 402        struct iw_quality       spy_thr_high;   /* High threshold */
 403        u_char                  spy_thr_under[IW_MAX_SPY];
 404};
 405
 406/* --------------------- DEVICE WIRELESS DATA --------------------- */
 407/*
 408 * This is all the wireless data specific to a device instance that
 409 * is managed by the core of Wireless Extensions or the 802.11 layer.
 410 * We only keep pointer to those structures, so that a driver is free
 411 * to share them between instances.
 412 * This structure should be initialised before registering the device.
 413 * Access to this data follow the same rules as any other struct net_device
 414 * data (i.e. valid as long as struct net_device exist, same locking rules).
 415 */
 416/* Forward declaration */
 417struct libipw_device;
 418/* The struct */
 419struct iw_public_data {
 420        /* Driver enhanced spy support */
 421        struct iw_spy_data *            spy_data;
 422        /* Legacy structure managed by the ipw2x00-specific IEEE 802.11 layer */
 423        struct libipw_device *          libipw;
 424};
 425
 426/**************************** PROTOTYPES ****************************/
 427/*
 428 * Functions part of the Wireless Extensions (defined in net/core/wireless.c).
 429 * Those may be called only within the kernel.
 430 */
 431
 432/* First : function strictly used inside the kernel */
 433
 434/* Handle /proc/net/wireless, called in net/code/dev.c */
 435extern int dev_get_wireless_info(char * buffer, char **start, off_t offset,
 436                                 int length);
 437
 438/* Second : functions that may be called by driver modules */
 439
 440/* Send a single event to user space */
 441extern void wireless_send_event(struct net_device *     dev,
 442                                unsigned int            cmd,
 443                                union iwreq_data *      wrqu,
 444                                const char *            extra);
 445
 446/* We may need a function to send a stream of events to user space.
 447 * More on that later... */
 448
 449/* Standard handler for SIOCSIWSPY */
 450extern int iw_handler_set_spy(struct net_device *       dev,
 451                              struct iw_request_info *  info,
 452                              union iwreq_data *        wrqu,
 453                              char *                    extra);
 454/* Standard handler for SIOCGIWSPY */
 455extern int iw_handler_get_spy(struct net_device *       dev,
 456                              struct iw_request_info *  info,
 457                              union iwreq_data *        wrqu,
 458                              char *                    extra);
 459/* Standard handler for SIOCSIWTHRSPY */
 460extern int iw_handler_set_thrspy(struct net_device *    dev,
 461                                 struct iw_request_info *info,
 462                                 union iwreq_data *     wrqu,
 463                                 char *                 extra);
 464/* Standard handler for SIOCGIWTHRSPY */
 465extern int iw_handler_get_thrspy(struct net_device *    dev,
 466                                 struct iw_request_info *info,
 467                                 union iwreq_data *     wrqu,
 468                                 char *                 extra);
 469/* Driver call to update spy records */
 470extern void wireless_spy_update(struct net_device *     dev,
 471                                unsigned char *         address,
 472                                struct iw_quality *     wstats);
 473
 474/************************* INLINE FUNTIONS *************************/
 475/*
 476 * Function that are so simple that it's more efficient inlining them
 477 */
 478
 479static inline int iwe_stream_lcp_len(struct iw_request_info *info)
 480{
 481#ifdef CONFIG_COMPAT
 482        if (info->flags & IW_REQUEST_FLAG_COMPAT)
 483                return IW_EV_COMPAT_LCP_LEN;
 484#endif
 485        return IW_EV_LCP_LEN;
 486}
 487
 488static inline int iwe_stream_point_len(struct iw_request_info *info)
 489{
 490#ifdef CONFIG_COMPAT
 491        if (info->flags & IW_REQUEST_FLAG_COMPAT)
 492                return IW_EV_COMPAT_POINT_LEN;
 493#endif
 494        return IW_EV_POINT_LEN;
 495}
 496
 497static inline int iwe_stream_event_len_adjust(struct iw_request_info *info,
 498                                              int event_len)
 499{
 500#ifdef CONFIG_COMPAT
 501        if (info->flags & IW_REQUEST_FLAG_COMPAT) {
 502                event_len -= IW_EV_LCP_LEN;
 503                event_len += IW_EV_COMPAT_LCP_LEN;
 504        }
 505#endif
 506
 507        return event_len;
 508}
 509
 510/*------------------------------------------------------------------*/
 511/*
 512 * Wrapper to add an Wireless Event to a stream of events.
 513 */
 514static inline char *
 515iwe_stream_add_event(struct iw_request_info *info, char *stream, char *ends,
 516                     struct iw_event *iwe, int event_len)
 517{
 518        int lcp_len = iwe_stream_lcp_len(info);
 519
 520        event_len = iwe_stream_event_len_adjust(info, event_len);
 521
 522        /* Check if it's possible */
 523        if(likely((stream + event_len) < ends)) {
 524                iwe->len = event_len;
 525                /* Beware of alignement issues on 64 bits */
 526                memcpy(stream, (char *) iwe, IW_EV_LCP_PK_LEN);
 527                memcpy(stream + lcp_len, &iwe->u,
 528                       event_len - lcp_len);
 529                stream += event_len;
 530        }
 531        return stream;
 532}
 533
 534/*------------------------------------------------------------------*/
 535/*
 536 * Wrapper to add an short Wireless Event containing a pointer to a
 537 * stream of events.
 538 */
 539static inline char *
 540iwe_stream_add_point(struct iw_request_info *info, char *stream, char *ends,
 541                     struct iw_event *iwe, char *extra)
 542{
 543        int event_len = iwe_stream_point_len(info) + iwe->u.data.length;
 544        int point_len = iwe_stream_point_len(info);
 545        int lcp_len   = iwe_stream_lcp_len(info);
 546
 547        /* Check if it's possible */
 548        if(likely((stream + event_len) < ends)) {
 549                iwe->len = event_len;
 550                memcpy(stream, (char *) iwe, IW_EV_LCP_PK_LEN);
 551                memcpy(stream + lcp_len,
 552                       ((char *) &iwe->u) + IW_EV_POINT_OFF,
 553                       IW_EV_POINT_PK_LEN - IW_EV_LCP_PK_LEN);
 554                memcpy(stream + point_len, extra, iwe->u.data.length);
 555                stream += event_len;
 556        }
 557        return stream;
 558}
 559
 560/*------------------------------------------------------------------*/
 561/*
 562 * Wrapper to add a value to a Wireless Event in a stream of events.
 563 * Be careful, this one is tricky to use properly :
 564 * At the first run, you need to have (value = event + IW_EV_LCP_LEN).
 565 */
 566static inline char *
 567iwe_stream_add_value(struct iw_request_info *info, char *event, char *value,
 568                     char *ends, struct iw_event *iwe, int event_len)
 569{
 570        int lcp_len = iwe_stream_lcp_len(info);
 571
 572        /* Don't duplicate LCP */
 573        event_len -= IW_EV_LCP_LEN;
 574
 575        /* Check if it's possible */
 576        if(likely((value + event_len) < ends)) {
 577                /* Add new value */
 578                memcpy(value, &iwe->u, event_len);
 579                value += event_len;
 580                /* Patch LCP */
 581                iwe->len = value - event;
 582                memcpy(event, (char *) iwe, lcp_len);
 583        }
 584        return value;
 585}
 586
 587#endif  /* _IW_HANDLER_H */
 588
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