bool get_local_ips(const char *ifname, char **ipv4, char **ipv6);
bool check_port_open(const char *host, uint16_t port);
-char *b64_encode(const unsigned char *data, size_t input_length);
+char *b64_encode(const uint8_t *data, size_t input_length);
+uint8_t *b64_decode(const char *data, size_t input_length, size_t *output_length);
char *str_replace(const char *orig, const char *rep, const char *with);
char *read_key(const char *filename);