addr_check.h

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

 
#ifndef ADDR_CHECK_H
#define ADDR_CHECK_H
 
#include <stddef.h>
#include <string.h>

#define ADDR_TRON_LEN  34U

static inline bool addr_is_base58(const char *s)
{
    static const char *const B58 =
        "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
    if (s == NULL) { return false; }
    /* An empty string has no character outside the alphabet, which would make a
     * plain loop answer "yes". Callers check the length too, but this is the
     * function whose name promises the answer, so it answers correctly. */
    if (*s == '\0') { return false; }
    for (const char *p = s; *p != '\0'; p++) {
        if (strchr(B58, *p) == NULL) { return false; }
    }
    return true;
}

static inline bool addr_tron_plausible(const char *s)
{
    return (s != NULL) && (strlen(s) == ADDR_TRON_LEN) && (s[0] == 'T') &&
           addr_is_base58(s);
}

static inline bool addr_tron_decode(const char *s, unsigned char out[25])
{
    static const char *const B58 =
        "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
    if (!addr_tron_plausible(s)) { return false; }
    memset(out, 0, 25U);
    for (const char *p = s; *p != '\0'; p++) {
        unsigned carry = static_cast<unsigned>(strchr(B58, *p) - B58);
        for (int j = 24; j >= 0; j--) {
            carry += 58U * out[j];
            out[j] = static_cast<unsigned char>(carry & 0xFFU);
            carry >>= 8;
        }
        if (carry != 0U) { return false; }   /* more than 25 bytes */
    }
    return out[0] == 0x41U;
}
 
#endif /* ADDR_CHECK_H */