owlps/libowlps-client/libowlps-client.c

/*
 * This file is part of the Owl Positioning System (OwlPS).
 * OwlPS is a project of the University of Franche-Comte
 * (Université de Franche-Comté), France.
 *
 * Copyright © Université de Franche-Comté 2007-2012.
 *
 * Corresponding author: Matteo Cypriani <mcy@lm7.fr>
 *
 ***********************************************************************
 *
 * This software is governed by the CeCILL license under French law and
 * abiding by the rules of distribution of free software. You can use,
 * modify and/or redistribute the software under the terms of the CeCILL
 * license as circulated by CEA, CNRS and INRIA at the following URL:
 * http://www.cecill.info
 *
 * As a counterpart to the access to the source code and rights to copy,
 * modify and redistribute granted by the license, users are provided
 * only with a limited warranty and the software's authors, the holder
 * of the economic rights, and the successive licensors have only
 * limited liability.
 *
 * In this respect, the user's attention is drawn to the risks
 * associated with loading, using, modifying and/or developing or
 * reproducing the software by the user in light of its specific status
 * of free software, that may mean that it is complicated to manipulate,
 * and that also therefore means that it is reserved for developers and
 * experienced professionals having in-depth computer knowledge. Users
 * are therefore encouraged to load and test the software's suitability
 * as regards their requirements in conditions enabling the security of
 * their systems and/or data to be ensured and, more generally, to use
 * and operate it in the same conditions as regards security.
 *
 * The fact that you are presently reading this means that you have had
 * knowledge of the CeCILL license and that you accept its terms.
 *
 ***********************************************************************
 *
 * This is the main source file of libowlps-client.
 */


#include "owlps-client.h"

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>

#include <sys/param.h>



/*
 * Opens an UDP socket to the server whose IP address is 'dest_ip'
 * and which listens 'dest_port'. The server information is stored
 * into 'server'. The socket will send through the network interface
 * 'iface' if specified (if you want the interface to be selected,
 * automatically, this parameter should be NULL or an empty string).
 */
int owl_create_trx_socket(const char *const dest_ip,
                          const uint_fast16_t dest_port,
                          struct sockaddr_in *const server,
                          const char *const iface)
{
  struct sockaddr_in client ;

  int sockfd = owl_create_udp_trx_socket(dest_ip, dest_port,
                                         server, &client) ;
  if (sockfd < 0)
    {
      perror("Error! Cannot create UDP sending socket to the aggregation"
             " server") ;
      exit(OWL_ERR_SOCKET_CREATE) ;
    }

  // If we specified an interface name
  if (iface != NULL && iface[0] != '\0')
    owl_use_iface(sockfd, iface) ;

  return sockfd ;
}



/* Selects 'iface' as sending interface for the socket 'sockfd'. */
void owl_use_iface(const int sockfd, const char *const iface)
{
#if defined(linux) && defined(__GLIBC__)
  if (setsockopt(sockfd, SOL_SOCKET, SO_BINDTODEVICE, iface,
                 strlen(iface) + 1) == -1)
    {
      fprintf(stderr, "Error! Cannot select interface %s to send the"
              " packet: ", iface) ;
      perror("") ;
      fprintf(stderr, "Sending through the default interface.\n") ;
    }
#else // linux && __GLIBC__
  fprintf(stderr, "Cannot select interface %s to send the packet:"
	  " this option is currently Linux and GNU libc-specific.\n"
	  "Sending through the default interface.\n", iface) ;
#endif // linux && __GLIBC__
}



/*
 * Transmits a request.
 * No packet will be transmitted if the variable owl_run is (or
 * becomes) false.
 * nb_pkt: number of packets to transmit.
 * delay: delay between two transmissions, in milliseconds.
 */
void owl_send_request(const int sockfd,
                      const struct sockaddr_in *const server,
                      const void *const packet,
                      const uint_fast16_t packet_size,
                      const uint_fast16_t nb_pkt,
                      const uint_fast32_t delay)
{
  uint_fast16_t i ;

  if (nb_pkt == 0 || !owl_run)
    return ;

#ifdef DEBUG
  printf("Sent packets: ") ;
#endif // DEBUG

  // Transmit first packet:
  owl_send_packet(sockfd, server, packet, packet_size) ;

  // Transmit remaining packets (if any):
  for (i = 1 ; i < nb_pkt ; ++i)
    {
      uint16_t current_pkt = htons(i + 1) ;
      owl_msleep(delay) ; // Wait during the wanted delay
      if (! owl_run)
        break ;
      // Update the packet number:
      memcpy(&((char*) packet)[1], &current_pkt, sizeof(uint16_t)) ;
      owl_send_packet(sockfd, server, packet, packet_size) ;
    }

#ifdef DEBUG
  putchar('\n') ;
#endif // DEBUG
}



void owl_send_packet(const int sockfd,
                     const struct sockaddr_in *const server,
                     const void *const packet,
                     const uint_fast16_t packet_size)
{
  ssize_t nsent = sendto(sockfd, packet, packet_size, 0,
                         (struct sockaddr *) server,
                         (socklen_t) sizeof(*server)) ;
  if (nsent != (ssize_t) packet_size)
    {
      perror("Error sending data to the aggregation server") ;
      exit(OWL_ERR_SOCKET_SEND) ;
    }

#ifdef DEBUG
  putchar('.') ;
  fflush(stdout) ;
#endif // DEBUG
}