parameters.c

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/*********************************************************************
 *
 * Filename:      parameters.c
 * Version:       1.0
 * Description:   A more general way to handle (pi,pl,pv) parameters
 * Status:        Experimental.
 * Author:        Dag Brattli <[email protected]>
 * Created at:    Mon Jun  7 10:25:11 1999
 * Modified at:   Sun Jan 30 14:08:39 2000
 * Modified by:   Dag Brattli <[email protected]>
 *
 *     Copyright (c) 1999-2000 Dag Brattli, All Rights Reserved.
 *
 *     This program is free software; you can redistribute it and/or
 *     modify it under the terms of the GNU General Public License as
 *     published by the Free Software Foundation; either version 2 of
 *     the License, or (at your option) any later version.
 *
 *     This program is distributed in the hope that it will be useful,
 *     but WITHOUT ANY WARRANTY; without even the implied warranty of
 *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 *     GNU General Public License for more details.
 *
 *     You should have received a copy of the GNU General Public License
 *     along with this program; if not, write to the Free Software
 *     Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 *     MA 02111-1307 USA
 *
 ********************************************************************/

#include <linux/types.h>
#include <linux/module.h>

#include <asm/unaligned.h>
#include <asm/byteorder.h>

#include <net/irda/irda.h>
#include <net/irda/parameters.h>

static int irda_extract_integer(void *self, __u8 *buf, int len, __u8 pi,
                PV_TYPE type, PI_HANDLER func);
static int irda_extract_string(void *self, __u8 *buf, int len, __u8 pi,
                   PV_TYPE type, PI_HANDLER func);
static int irda_extract_octseq(void *self, __u8 *buf, int len, __u8 pi,
                   PV_TYPE type, PI_HANDLER func);
static int irda_extract_no_value(void *self, __u8 *buf, int len, __u8 pi,
                 PV_TYPE type, PI_HANDLER func);

static int irda_insert_integer(void *self, __u8 *buf, int len, __u8 pi,
                   PV_TYPE type, PI_HANDLER func);
static int irda_insert_no_value(void *self, __u8 *buf, int len, __u8 pi,
                PV_TYPE type, PI_HANDLER func);

static int irda_param_unpack(__u8 *buf, char *fmt, ...);

/* Parameter value call table. Must match PV_TYPE */
static PV_HANDLER pv_extract_table[] = {
    irda_extract_integer, /* Handler for any length integers */
    irda_extract_integer, /* Handler for 8  bits integers */
    irda_extract_integer, /* Handler for 16 bits integers */
    irda_extract_string,  /* Handler for strings */
    irda_extract_integer, /* Handler for 32 bits integers */
    irda_extract_octseq,  /* Handler for octet sequences */
    irda_extract_no_value /* Handler for no value parameters */
};

static PV_HANDLER pv_insert_table[] = {
    irda_insert_integer, /* Handler for any length integers */
    irda_insert_integer, /* Handler for 8  bits integers */
    irda_insert_integer, /* Handler for 16 bits integers */
    NULL,                /* Handler for strings */
    irda_insert_integer, /* Handler for 32 bits integers */
    NULL,                /* Handler for octet sequences */
    irda_insert_no_value /* Handler for no value parameters */
};

/*
 * Function irda_insert_no_value (self, buf, len, pi, type, func)
 */
static int irda_insert_no_value(void *self, __u8 *buf, int len, __u8 pi,
                PV_TYPE type, PI_HANDLER func)
{
    irda_param_t p;
    int ret;

    p.pi = pi;
    p.pl = 0;

    /* Call handler for this parameter */
    ret = (*func)(self, &p, PV_GET);

    /* Extract values anyway, since handler may need them */
    irda_param_pack(buf, "bb", p.pi, p.pl);

    if (ret < 0)
        return ret;

    return 2; /* Inserted pl+2 bytes */
}

/*
 * Function irda_extract_no_value (self, buf, len, type, func)
 *
 *    Extracts a parameter without a pv field (pl=0)
 *
 */
static int irda_extract_no_value(void *self, __u8 *buf, int len, __u8 pi,
                 PV_TYPE type, PI_HANDLER func)
{
    irda_param_t p;
    int ret;

    /* Extract values anyway, since handler may need them */
    irda_param_unpack(buf, "bb", &p.pi, &p.pl);

    /* Call handler for this parameter */
    ret = (*func)(self, &p, PV_PUT);

    if (ret < 0)
        return ret;

    return 2; /* Extracted pl+2 bytes */
}

/*
 * Function irda_insert_integer (self, buf, len, pi, type, func)
 */
static int irda_insert_integer(void *self, __u8 *buf, int len, __u8 pi,
                   PV_TYPE type, PI_HANDLER func)
{
    irda_param_t p;
    int n = 0;
    int err;

    p.pi = pi;             /* In case handler needs to know */
    p.pl = type & PV_MASK; /* The integer type codes the length as well */
    p.pv.i = 0;            /* Clear value */

    /* Call handler for this parameter */
    err = (*func)(self, &p, PV_GET);
    if (err < 0)
        return err;

    /*
     * If parameter length is still 0, then (1) this is an any length
     * integer, and (2) the handler function does not care which length
     * we choose to use, so we pick the one the gives the fewest bytes.
     */
    if (p.pl == 0) {
        if (p.pv.i < 0xff) {
            IRDA_DEBUG(2, "%s(), using 1 byte\n", __func__);
            p.pl = 1;
        } else if (p.pv.i < 0xffff) {
            IRDA_DEBUG(2, "%s(), using 2 bytes\n", __func__);
            p.pl = 2;
        } else {
            IRDA_DEBUG(2, "%s(), using 4 bytes\n", __func__);
            p.pl = 4; /* Default length */
        }
    }
    /* Check if buffer is long enough for insertion */
    if (len < (2+p.pl)) {
        IRDA_WARNING("%s: buffer too short for insertion!\n",
                 __func__);
        return -1;
    }
    IRDA_DEBUG(2, "%s(), pi=%#x, pl=%d, pi=%d\n", __func__,
           p.pi, p.pl, p.pv.i);
    switch (p.pl) {
    case 1:
        n += irda_param_pack(buf, "bbb", p.pi, p.pl, (__u8) p.pv.i);
        break;
    case 2:
        if (type & PV_BIG_ENDIAN)
            p.pv.i = cpu_to_be16((__u16) p.pv.i);
        else
            p.pv.i = cpu_to_le16((__u16) p.pv.i);
        n += irda_param_pack(buf, "bbs", p.pi, p.pl, (__u16) p.pv.i);
        break;
    case 4:
        if (type & PV_BIG_ENDIAN)
            cpu_to_be32s(&p.pv.i);
        else
            cpu_to_le32s(&p.pv.i);
        n += irda_param_pack(buf, "bbi", p.pi, p.pl, p.pv.i);

        break;
    default:
        IRDA_WARNING("%s: length %d not supported\n",
                 __func__, p.pl);
        /* Skip parameter */
        return -1;
    }

    return p.pl+2; /* Inserted pl+2 bytes */
}

/*
 * Function irda_extract integer (self, buf, len, pi, type, func)
 *
 *    Extract a possibly variable length integer from buffer, and call
 *    handler for processing of the parameter
 */
static int irda_extract_integer(void *self, __u8 *buf, int len, __u8 pi,
                PV_TYPE type, PI_HANDLER func)
{
    irda_param_t p;
    int n = 0;
    int extract_len;    /* Real length we extract */
    int err;

    p.pi = pi;     /* In case handler needs to know */
    p.pl = buf[1]; /* Extract length of value */
    p.pv.i = 0;    /* Clear value */
    extract_len = p.pl; /* Default : extract all */

    /* Check if buffer is long enough for parsing */
    if (len < (2+p.pl)) {
        IRDA_WARNING("%s: buffer too short for parsing! "
                 "Need %d bytes, but len is only %d\n",
                 __func__, p.pl, len);
        return -1;
    }

    /*
     * Check that the integer length is what we expect it to be. If the
     * handler want a 16 bits integer then a 32 bits is not good enough
     * PV_INTEGER means that the handler is flexible.
     */
    if (((type & PV_MASK) != PV_INTEGER) && ((type & PV_MASK) != p.pl)) {
        IRDA_ERROR("%s: invalid parameter length! "
               "Expected %d bytes, but value had %d bytes!\n",
               __func__, type & PV_MASK, p.pl);

        /* Most parameters are bit/byte fields or little endian,
         * so it's ok to only extract a subset of it (the subset
         * that the handler expect). This is necessary, as some
         * broken implementations seems to add extra undefined bits.
         * If the parameter is shorter than we expect or is big
         * endian, we can't play those tricks. Jean II */
        if((p.pl < (type & PV_MASK)) || (type & PV_BIG_ENDIAN)) {
            /* Skip parameter */
            return p.pl+2;
        } else {
            /* Extract subset of it, fallthrough */
            extract_len = type & PV_MASK;
        }
    }


    switch (extract_len) {
    case 1:
        n += irda_param_unpack(buf+2, "b", &p.pv.i);
        break;
    case 2:
        n += irda_param_unpack(buf+2, "s", &p.pv.i);
        if (type & PV_BIG_ENDIAN)
            p.pv.i = be16_to_cpu((__u16) p.pv.i);
        else
            p.pv.i = le16_to_cpu((__u16) p.pv.i);
        break;
    case 4:
        n += irda_param_unpack(buf+2, "i", &p.pv.i);
        if (type & PV_BIG_ENDIAN)
            be32_to_cpus(&p.pv.i);
        else
            le32_to_cpus(&p.pv.i);
        break;
    default:
        IRDA_WARNING("%s: length %d not supported\n",
                 __func__, p.pl);

        /* Skip parameter */
        return p.pl+2;
    }

    IRDA_DEBUG(2, "%s(), pi=%#x, pl=%d, pi=%d\n", __func__,
           p.pi, p.pl, p.pv.i);
    /* Call handler for this parameter */
    err = (*func)(self, &p, PV_PUT);
    if (err < 0)
        return err;

    return p.pl+2; /* Extracted pl+2 bytes */
}

/*
 * Function irda_extract_string (self, buf, len, type, func)
 */
static int irda_extract_string(void *self, __u8 *buf, int len, __u8 pi,
                   PV_TYPE type, PI_HANDLER func)
{
    char str[33];
    irda_param_t p;
    int err;

    IRDA_DEBUG(2, "%s()\n", __func__);

    p.pi = pi;     /* In case handler needs to know */
    p.pl = buf[1]; /* Extract length of value */
    if (p.pl > 32)
        p.pl = 32;

    IRDA_DEBUG(2, "%s(), pi=%#x, pl=%d\n", __func__,
           p.pi, p.pl);

    /* Check if buffer is long enough for parsing */
    if (len < (2+p.pl)) {
        IRDA_WARNING("%s: buffer too short for parsing! "
                 "Need %d bytes, but len is only %d\n",
                 __func__, p.pl, len);
        return -1;
    }

    /* Should be safe to copy string like this since we have already
     * checked that the buffer is long enough */
    strncpy(str, buf+2, p.pl);

    IRDA_DEBUG(2, "%s(), str=0x%02x 0x%02x\n", __func__,
           (__u8) str[0], (__u8) str[1]);

    /* Null terminate string */
    str[p.pl] = '\0';

    p.pv.c = str; /* Handler will need to take a copy */

    /* Call handler for this parameter */
    err = (*func)(self, &p, PV_PUT);
    if (err < 0)
        return err;

    return p.pl+2; /* Extracted pl+2 bytes */
}

/*
 * Function irda_extract_octseq (self, buf, len, type, func)
 */
static int irda_extract_octseq(void *self, __u8 *buf, int len, __u8 pi,
                   PV_TYPE type, PI_HANDLER func)
{
    irda_param_t p;

    p.pi = pi;     /* In case handler needs to know */
    p.pl = buf[1]; /* Extract length of value */

    /* Check if buffer is long enough for parsing */
    if (len < (2+p.pl)) {
        IRDA_WARNING("%s: buffer too short for parsing! "
                 "Need %d bytes, but len is only %d\n",
                 __func__, p.pl, len);
        return -1;
    }

    IRDA_DEBUG(0, "%s(), not impl\n", __func__);

    return p.pl+2; /* Extracted pl+2 bytes */
}

/*
 * Function irda_param_pack (skb, fmt, ...)
 *
 *    Format:
 *        'i' = 32 bits integer
 *        's' = string
 *
 */
int irda_param_pack(__u8 *buf, char *fmt, ...)
{
    irda_pv_t arg;
    va_list args;
    char *p;
    int n = 0;

    va_start(args, fmt);

    for (p = fmt; *p != '\0'; p++) {
        switch (*p) {
        case 'b':  /* 8 bits unsigned byte */
            buf[n++] = (__u8)va_arg(args, int);
            break;
        case 's':  /* 16 bits unsigned short */
            arg.i = (__u16)va_arg(args, int);
            put_unaligned((__u16)arg.i, (__u16 *)(buf+n)); n+=2;
            break;
        case 'i':  /* 32 bits unsigned integer */
            arg.i = va_arg(args, __u32);
            put_unaligned(arg.i, (__u32 *)(buf+n)); n+=4;
            break;
#if 0
        case 'c': /* \0 terminated string */
            arg.c = va_arg(args, char *);
            strcpy(buf+n, arg.c);
            n += strlen(arg.c) + 1;
            break;
#endif
        default:
            va_end(args);
            return -1;
        }
    }
    va_end(args);

    return 0;
}
EXPORT_SYMBOL(irda_param_pack);

/*
 * Function irda_param_unpack (skb, fmt, ...)
 */
static int irda_param_unpack(__u8 *buf, char *fmt, ...)
{
    irda_pv_t arg;
    va_list args;
    char *p;
    int n = 0;

    va_start(args, fmt);

    for (p = fmt; *p != '\0'; p++) {
        switch (*p) {
        case 'b':  /* 8 bits byte */
            arg.ip = va_arg(args, __u32 *);
            *arg.ip = buf[n++];
            break;
        case 's':  /* 16 bits short */
            arg.ip = va_arg(args, __u32 *);
            *arg.ip = get_unaligned((__u16 *)(buf+n)); n+=2;
            break;
        case 'i':  /* 32 bits unsigned integer */
            arg.ip = va_arg(args, __u32 *);
            *arg.ip = get_unaligned((__u32 *)(buf+n)); n+=4;
            break;
#if 0
        case 'c':   /* \0 terminated string */
            arg.c = va_arg(args, char *);
            strcpy(arg.c, buf+n);
            n += strlen(arg.c) + 1;
            break;
#endif
        default:
            va_end(args);
            return -1;
        }

    }
    va_end(args);

    return 0;
}

/*
 * Function irda_param_insert (self, pi, buf, len, info)
 *
 *    Insert the specified parameter (pi) into buffer. Returns number of
 *    bytes inserted
 */
int irda_param_insert(void *self, __u8 pi, __u8 *buf, int len,
              pi_param_info_t *info)
{
    pi_minor_info_t *pi_minor_info;
    __u8 pi_minor;
    __u8 pi_major;
    int type;
    int ret = -1;
    int n = 0;

    IRDA_ASSERT(buf != NULL, return ret;);
    IRDA_ASSERT(info != NULL, return ret;);

    pi_minor = pi & info->pi_mask;
    pi_major = pi >> info->pi_major_offset;

    /* Check if the identifier value (pi) is valid */
    if ((pi_major > info->len-1) ||
        (pi_minor > info->tables[pi_major].len-1))
    {
        IRDA_DEBUG(0, "%s(), no handler for parameter=0x%02x\n",
               __func__, pi);

        /* Skip this parameter */
        return -1;
    }

    /* Lookup the info on how to parse this parameter */
    pi_minor_info = &info->tables[pi_major].pi_minor_call_table[pi_minor];

    /* Find expected data type for this parameter identifier (pi)*/
    type = pi_minor_info->type;

    /*  Check if handler has been implemented */
    if (!pi_minor_info->func) {
        IRDA_MESSAGE("%s: no handler for pi=%#x\n", __func__, pi);
        /* Skip this parameter */
        return -1;
    }

    /* Insert parameter value */
    ret = (*pv_insert_table[type & PV_MASK])(self, buf+n, len, pi, type,
                         pi_minor_info->func);
    return ret;
}
EXPORT_SYMBOL(irda_param_insert);

/*
 * Function irda_param_extract (self, buf, len, info)
 *
 *    Parse all parameters. If len is correct, then everything should be
 *    safe. Returns the number of bytes that was parsed
 *
 */
static int irda_param_extract(void *self, __u8 *buf, int len,
                  pi_param_info_t *info)
{
    pi_minor_info_t *pi_minor_info;
    __u8 pi_minor;
    __u8 pi_major;
    int type;
    int ret = -1;
    int n = 0;

    IRDA_ASSERT(buf != NULL, return ret;);
    IRDA_ASSERT(info != NULL, return ret;);

    pi_minor = buf[n] & info->pi_mask;
    pi_major = buf[n] >> info->pi_major_offset;

    /* Check if the identifier value (pi) is valid */
    if ((pi_major > info->len-1) ||
        (pi_minor > info->tables[pi_major].len-1))
    {
        IRDA_DEBUG(0, "%s(), no handler for parameter=0x%02x\n",
               __func__, buf[0]);

        /* Skip this parameter */
        return 2 + buf[n + 1];  /* Continue */
    }

    /* Lookup the info on how to parse this parameter */
    pi_minor_info = &info->tables[pi_major].pi_minor_call_table[pi_minor];

    /* Find expected data type for this parameter identifier (pi)*/
    type = pi_minor_info->type;

    IRDA_DEBUG(3, "%s(), pi=[%d,%d], type=%d\n", __func__,
           pi_major, pi_minor, type);

    /*  Check if handler has been implemented */
    if (!pi_minor_info->func) {
        IRDA_MESSAGE("%s: no handler for pi=%#x\n",
                 __func__, buf[n]);
        /* Skip this parameter */
        return 2 + buf[n + 1]; /* Continue */
    }

    /* Parse parameter value */
    ret = (*pv_extract_table[type & PV_MASK])(self, buf+n, len, buf[n],
                          type, pi_minor_info->func);
    return ret;
}

/*
 * Function irda_param_extract_all (self, buf, len, info)
 *
 *    Parse all parameters. If len is correct, then everything should be
 *    safe. Returns the number of bytes that was parsed
 *
 */
int irda_param_extract_all(void *self, __u8 *buf, int len,
               pi_param_info_t *info)
{
    int ret = -1;
    int n = 0;

    IRDA_ASSERT(buf != NULL, return ret;);
    IRDA_ASSERT(info != NULL, return ret;);

    /*
     * Parse all parameters. Each parameter must be at least two bytes
     * long or else there is no point in trying to parse it
     */
    while (len > 2) {
        ret = irda_param_extract(self, buf+n, len, info);
        if (ret < 0)
            return ret;

        n += ret;
        len -= ret;
    }
    return n;
}
EXPORT_SYMBOL(irda_param_extract_all);