// get sockaddr, IPv4 or IPv6:
static void *get_in_addr(struct sockaddr *sa) {
  if (sa->sa_family == AF_INET) {
    return &(((struct sockaddr_in*)sa)->sin_addr);
  }
  return &(((struct sockaddr_in6*)sa)->sin6_addr);
}

/*
  DEBUG TOOL
  print a packet
*/
static int p_printf_packet(p3_msg_t *packet) {
  return printf("Packet header (%lu): {magic_number: %X, packet_id: %x, TTL: %i,"
                " destination_host: %x, destination_plugin: %x, body_length: %u}\n",
                sizeof(*packet), packet->magic_number.value, packet->packet_id,
                packet->TTL, packet->destination_host, packet->destination_plugin,
                packet->body_length) +
    printf("Packet body: %s\n", (char *)packet + sizeof(*packet));
}

static int p_stop_server() {
  if (server_p != -1)
    close(server_p);
  server_p = -1;
  return 0;
}

/* Start the server on the specified port. The file descriptor of the server is stored in server_p */
static int p_start_server(char *port) {
  p_stop_server(); // STOP THE SERVER IF ALREADY STARTED

  int sockfd;
  struct addrinfo hints, *servinfo;
  int rv;

  memset(&hints, 0, sizeof hints);
  hints.ai_family = AF_UNSPEC; // set to AF_INET to force IPv4
  hints.ai_socktype = SOCK_DGRAM;
  hints.ai_flags = AI_PASSIVE; // use my IP
  if ((rv = getaddrinfo(NULL, port, &hints, &servinfo)) != 0) {
    fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
    return ERR_SYSCALL;
  }
  // loop through all the results and bind to the first we can
  if ((sockfd = socket(servinfo->ai_family, servinfo->ai_socktype, servinfo->ai_protocol)) == -1) {
    perror("socket");
    return ERR_SYSCALL;
  }
  if (bind(sockfd, servinfo->ai_addr, servinfo->ai_addrlen) == -1) {
    close(sockfd);
    perror("bind");
    return ERR_SYSCALL;
  }

  freeaddrinfo(servinfo);
  server_p = sockfd;
  return 0;
}