/* $OpenBSD: field.c,v 1.22 2017/04/02 21:23:44 tom Exp $        */
/* $EOM: field.c,v 1.11 2000/02/20 19:58:37 niklas Exp $         */

/*
 * Copyright (c) 1998, 1999 Niklas Hallqvist.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * This code was written under funding by Ericsson Radio Systems.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <netinet/in.h>

#include "constants.h"
#include "field.h"
#include "log.h"
#include "util.h"

static char    *field_debug_raw(u_int8_t *, size_t, struct constant_map **);
static char    *field_debug_num(u_int8_t *, size_t, struct constant_map **);
static char    *field_debug_mask(u_int8_t *, size_t, struct constant_map **);
static char    *field_debug_ign(u_int8_t *, size_t, struct constant_map **);
static char    *field_debug_cst(u_int8_t *, size_t, struct constant_map **);

/* Contents must match the enum in struct field.  */
static char    *(*decode_field[]) (u_int8_t *, size_t,
    struct constant_map **) = {
        field_debug_raw,
        field_debug_num,
        field_debug_mask,
        field_debug_ign,
        field_debug_cst
};

/*
 * Return a string showing the hexadecimal contents of the LEN-sized buffer
 * BUF.  MAPS should be zero and is only here because the API requires it.
 */
static char *
field_debug_raw(u_int8_t *buf, size_t len, struct constant_map **maps)
{
        return raw2hex(buf, len);
}

/*
 * Convert the unsigned LEN-sized number at BUF of network byteorder to a
 * 32-bit unsigned integer of host byteorder pointed to by VAL.
 */
static int
extract_val(u_int8_t *buf, size_t len, u_int32_t *val)
{
        switch (len) {
        case 1:
                *val = *buf;
                break;
        case 2:
                *val = decode_16(buf);
                break;
        case 4:
                *val = decode_32(buf);
                break;
        default:
                return -1;
        }
        return 0;
}

/*
 * Return a textual representation of the unsigned number pointed to by BUF
 * which is LEN octets long.  MAPS should be zero and is only here because
 * the API requires it.
 */
static char *
field_debug_num(u_int8_t *buf, size_t len, struct constant_map **maps)
{
        char           *retval;
        u_int32_t       val;

        if (extract_val(buf, len, &val))
                return NULL;
        if (asprintf(&retval, "%u", val) == -1)
                return NULL;
        return retval;
}

/*
 * Return the symbolic names of the flags pointed to by BUF which is LEN
 * octets long, using the constant maps MAPS.
 */
static char *
field_debug_mask(u_int8_t *buf, size_t len, struct constant_map **maps)
{
        u_int32_t       val;
        u_int32_t       bit;
        char           *retval, *new_buf, *name;
        size_t          buf_sz;

        if (extract_val(buf, len, &val))
                return NULL;

        /* Size for brackets, two spaces and a NUL terminator.  */
        buf_sz = 4;
        retval = malloc(buf_sz);
        if (!retval)
                return NULL;

        strlcpy(retval, "[ ", buf_sz);
        for (bit = 1; bit; bit <<= 1) {
                if (val & bit) {
                        name = constant_name_maps(maps, bit);
                        buf_sz += strlen(name) + 1;
                        new_buf = realloc(retval, buf_sz);
                        if (!new_buf) {
                                free(retval);
                                return NULL;
                        }
                        retval = new_buf;
                        strlcat(retval, name, buf_sz);
                        strlcat(retval, " ", buf_sz);
                }
        }
        strlcat(retval, "]", buf_sz);
        return retval;
}

/*
 * Just a dummy needed to skip the unused LEN sized space at BUF.  MAPS
 * should be zero and is only here because the API requires it.
 */
static char *
field_debug_ign(u_int8_t *buf, size_t len, struct constant_map **maps)
{
        return NULL;
}

/*
 * Return the symbolic name of a constant pointed to by BUF which is LEN
 * octets long, using the constant maps MAPS.
 */
static char *
field_debug_cst(u_int8_t *buf, size_t len, struct constant_map **maps)
{
        u_int32_t       val;

        if (extract_val(buf, len, &val))
                return NULL;

        return strdup(constant_name_maps(maps, val));
}

/* Pretty-print a field from BUF as described by F.  */
void
field_dump_field(struct field *f, u_int8_t *buf)
{
        char    *value;

        value = decode_field[(int) f->type] (buf + f->offset, f->len, f->maps);
        if (value) {
                LOG_DBG((LOG_MESSAGE, 70, "%s: %s", f->name, value));
                free(value);
        }
}

/* Pretty-print all the fields of BUF as described in FIELDS.  */
void
field_dump_payload(struct field *fields, u_int8_t *buf)
{
        struct field   *field;

        for (field = fields; field->name; field++)
                field_dump_field(field, buf);
}

/* Return the numeric value of the field F of BUF.  */
u_int32_t
field_get_num(struct field *f, u_int8_t *buf)
{
        u_int32_t       val;

        if (extract_val(buf + f->offset, f->len, &val))
                return 0;
        return val;
}

/* Stash the number VAL into BUF's field F.  */
void
field_set_num(struct field *f, u_int8_t *buf, u_int32_t val)
{
        switch (f->len) {
        case 1:
                buf[f->offset] = val;
                break;
        case 2:
                encode_16(buf + f->offset, val);
                break;
        case 4:
                encode_32(buf + f->offset, val);
                break;
        }
}

/* Stash BUF's raw field F into VAL.  */
void
field_get_raw(struct field *f, u_int8_t *buf, u_int8_t *val)
{
        memcpy(val, buf + f->offset, f->len);
}

/* Stash the buffer VAL into BUF's field F.  */
void
field_set_raw(struct field *f, u_int8_t *buf, u_int8_t *val)
{
        memcpy(buf + f->offset, val, f->len);
}