Function bech32_decode

common/bech32.c:94–155

}

bech32_encoding bech32_decode(char* hrp, uint8_t *data, size_t *data_len, const char *input, size_t max_input_len) {
    uint32_t chk = 1;
    size_t i;
    size_t input_len = strlen(input);
    size_t hrp_len;
    int have_lower = 0, have_upper = 0;
    if (input_len < 8 || input_len > max_input_len) {
        return BECH32_ENCODING_NONE;
    }
    *data_len = 0;
    while (*data_len < input_len && input[(input_len - 1) - *data_len] != '1') {
        ++(*data_len);
    }
    hrp_len = input_len - (1 + *data_len);
    if (1 + *data_len >= input_len || *data_len < 6) {
        return BECH32_ENCODING_NONE;
    }
    *(data_len) -= 6;
    for (i = 0; i < hrp_len; ++i) {
        int ch = input[i];
        if (ch < 33 || ch > 126) {
            return BECH32_ENCODING_NONE;
        }
        if (ch >= 'a' && ch <= 'z') {
            have_lower = 1;
        } else if (ch >= 'A' && ch <= 'Z') {
            have_upper = 1;
            ch = (ch - 'A') + 'a';
        }
        hrp[i] = ch;
        chk = bech32_polymod_step(chk) ^ (ch >> 5);
    }
    hrp[i] = 0;
    chk = bech32_polymod_step(chk);
    for (i = 0; i < hrp_len; ++i) {
        chk = bech32_polymod_step(chk) ^ (input[i] & 0x1f);
    }
    ++i;
    while (i < input_len) {
        int v = (input[i] & 0x80) ? -1 : bech32_charset_rev[(int)input[i]];
        if (input[i] >= 'a' && input[i] <= 'z') have_lower = 1;
        if (input[i] >= 'A' && input[i] <= 'Z') have_upper = 1;
        if (v == -1) {
            return BECH32_ENCODING_NONE;
        }
        chk = bech32_polymod_step(chk) ^ v;
        if (i + 6 < input_len) {
            data[i - (1 + hrp_len)] = v;
        }
        ++i;
    }
    if (have_lower && have_upper) {
        return BECH32_ENCODING_NONE;
    }
    if (chk == bech32_final_constant(BECH32_ENCODING_BECH32)) {
        return BECH32_ENCODING_BECH32;
    } else if (chk == bech32_final_constant(BECH32_ENCODING_BECH32M)) {
        return BECH32_ENCODING_BECH32M;