encode_data
encode_data((uint8_t *)(dp + 1), dp->Length - sizeof(*dp)));
ssid = encode_data((uint8_t *)p->SSID, sizeof(p->SSID));
data_str = encode_data(p->data, len);
mac_addr = encode_data(p->mac_addr, addr_len);
len = encode_data(MINUSNUL(key->size),
len = encode_data(MINUSNUL(val->size),
static int encode_data(size_t, char *, char **);