settings_rules.h

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/*
 * SPDX-License-Identifier: LGPL-3.0-or-later
 * Copyright (c) 2026 Cryptnox SA
 */

 
#ifndef SETTINGS_RULES_H
#define SETTINGS_RULES_H
 
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
 
#include "CW_Utils.h"     /* secure_wipe (CODING_RULES §1.4) */
#include "civil_time.h"   /* CIVIL_DST__COUNT */
#include "keccak256.h"
#include "settings.h"     /* TZ_OFFSET_MIN / _MAX, SETTINGS_PAYOUT_MAX */
 
/******************************************************************
 * Time zone
 ******************************************************************/
 
/* Minutes east of UTC are stored biased, so they fit the unsigned NVS helpers
 * and a missing key reads as UTC rather than as UTC-12. */
#define TZ_OFFSET_BIAS 720

static inline bool tz_offset_valid(long minutes)
{
    return (minutes >= TZ_OFFSET_MIN) && (minutes <= TZ_OFFSET_MAX);
}

static inline uint32_t tz_offset_encode(int16_t minutes)
{
    return (uint32_t)((int32_t)minutes + TZ_OFFSET_BIAS);
}

static inline int16_t tz_offset_decode(uint32_t raw)
{
    if (raw > (uint32_t)(TZ_OFFSET_BIAS + TZ_OFFSET_MAX)) {
        return 0;
    }
    return (int16_t)((int32_t)raw - TZ_OFFSET_BIAS);
}

static inline bool tz_dst_valid(long rule)
{
    return (rule >= 0) && (rule < (long)CIVIL_DST__COUNT);
}

static inline uint8_t tz_dst_decode(uint8_t r)
{
    return (r < (uint8_t)CIVIL_DST__COUNT) ? r : (uint8_t)CIVIL_DST_NONE;
}
 
/******************************************************************
 * Gas fees
 ******************************************************************/
 
/* Bounds are the ones the panel's steppers used to enforce, so a stored value
 * cannot become something the old UI could not express. */
#define FEE_GWEI_MIN  1UL
#define FEE_GWEI_MAX  500UL

typedef enum {
    FEE_PAIR_OK = 0,
    FEE_PAIR_OUT_OF_RANGE,   
    FEE_PAIR_TIP_ABOVE_MAX,  
} fee_pair_t;

static inline fee_pair_t fee_pair_check(unsigned long max_gwei, unsigned long prio_gwei)
{
    if ((max_gwei < FEE_GWEI_MIN) || (max_gwei > FEE_GWEI_MAX) ||
        (prio_gwei < FEE_GWEI_MIN) || (prio_gwei > FEE_GWEI_MAX)) {
        return FEE_PAIR_OUT_OF_RANGE;
    }
    if (prio_gwei > max_gwei) { return FEE_PAIR_TIP_ABOVE_MAX; }
    return FEE_PAIR_OK;
}
 
/******************************************************************
 * Admin code
 ******************************************************************/
 
#define ADMIN_SALT_LEN    16U
#define ADMIN_HASH_LEN    32U
/* Longest code that goes into the digest. Deliberately NOT ui.cpp's
 * ADMIN_CODE_MAX (9) — same name, different layer. Anything past this is
 * silently dropped from the hash, so keep it comfortably above the UI's cap. */
#define ADMIN_CODE_HASH_MAX  32U

static inline void admin_derive(const char *code, const uint8_t *salt,
                                uint8_t out[ADMIN_HASH_LEN])
{
    uint8_t buf[ADMIN_SALT_LEN + ADMIN_CODE_HASH_MAX];
    const size_t clen = strnlen(code, ADMIN_CODE_HASH_MAX);
 
    (void)memcpy(buf, salt, ADMIN_SALT_LEN);
    (void)memcpy(buf + ADMIN_SALT_LEN, code, clen);
    keccak256(buf, ADMIN_SALT_LEN + clen, out);
    CW_Utils::secure_wipe(buf, sizeof(buf));
}
 
/******************************************************************
 * Dual-stored addresses
 ******************************************************************/

static inline bool settings_addr_normalise(bool tron, const char *addr,
                                           char norm[SETTINGS_PAYOUT_MAX])
{
    if ((addr == NULL) || (addr[0] == '\0')) { return false; }
    if (strlen(addr) >= SETTINGS_PAYOUT_MAX) { return false; }
 
    if (tron) {
        (void)snprintf(norm, SETTINGS_PAYOUT_MAX, "%s", addr);
    } else {
        const bool prefixed = (addr[0] == '0') && ((addr[1] == 'x') || (addr[1] == 'X'));
        (void)snprintf(norm, SETTINGS_PAYOUT_MAX, "0x%s", prefixed ? (addr + 2) : addr);
    }
    return true;
}
 
#endif /* SETTINGS_RULES_H */