udpbroadcast.c

/* Inspired by code here: http://developerweb.net/viewtopic.php?pid=32260 */

#ifdef WIN32
# include <winsock2.h>
# include <io.h>
# define  socklen_t int
# define  sockopt_t char
#else
# include <netdb.h>
# include <netinet/in.h>
# include <arpa/inet.h>
# include <sys/time.h>
# include <sys/types.h>
# include <sys/socket.h>
# include <unistd.h>
# include <time.h>
# define  sockopt_t int
#endif
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#define PORT 2080
#include "udpbroadcast.h"

typedef struct speer {
  SOCKET socket;
  struct sockaddr_in addr;
} speer;

#define mkspeer(tpeer) ((speer *) tpeer)

int initialized = 0;
static void init(){
  if (initialized)
    return;
  initialized = 1;
  WSADATA WSAData;
  if (WSAStartup (MAKEWORD(2,2), &WSAData) != 0) 
    {
      printf("WSAStartup failed!\n");
      exit(2);
    }
}

log_fun the_log_fun = NULL;

void set_log_fun(log_fun fun)
{
  the_log_fun = fun;
}

void ulog(const char* msg) {
  if (the_log_fun != NULL) {
    (*the_log_fun)(msg);
  }
}

tpeer peer_create(int isServer)
{
  init();
  speer *p = (speer *)malloc(sizeof(speer));
  sockopt_t broadcast=1;

  if ((p->socket = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
    perror("socket");
    exit(1);
  }
  if ((setsockopt(p->socket, SOL_SOCKET, SO_BROADCAST,
                  &broadcast, sizeof broadcast)) == -1) {
    perror("setsockopt - SO_SOCKET ");
    exit(1);
  }
  printf("Socket created\n");

  memset(&p->addr, 0, sizeof p->addr);
  p->addr.sin_family = AF_INET;
  p->addr.sin_port = htons(PORT);
  p->addr.sin_addr.s_addr = INADDR_BROADCAST;

  if (isServer) {
    p->addr.sin_addr.s_addr = INADDR_ANY;
    if (bind(p->socket, (struct sockaddr*)&p->addr,
             sizeof p->addr) == -1) {
      perror("bind");
      char buf[32];
      sprintf(buf, "bind %d", WSAGetLastError());
      ulog(buf);
      exit(1);
    }
  }

  return p;
}


int peer_broadcast(tpeer peerIn, char* msg, unsigned int size)
{
  speer* p = mkspeer(peerIn);
  int val = sendto(p->socket, msg, size, 0, 
                   (struct sockaddr *)&p->addr, sizeof p->addr);
  if (val == -1) {
    char buf[32];
    sprintf(buf, "broadcast %d", WSAGetLastError());
    ulog(buf);
  }
  return val;
}

void peer_destroy(tpeer p)
{
  free((speer*) p);
}

/* timneout is milliseconds */
int peer_select(tpeer peerIn, int timeout) {
  speer* p = mkspeer(peerIn);
  int n;
  fd_set set;
  struct timeval timev = { 0, timeout*1000 };
  FD_ZERO(&set);
  FD_SET(p->socket, &set);
  
  return select(p->socket+1, &set, NULL, NULL, &timev);
}

int peer_receive(tpeer peerIn, char* buf, int bufsize) 
{
  speer* p = mkspeer(peerIn);
  socklen_t addr_len = sizeof p->addr;
  return recvfrom(p->socket, buf, bufsize, 0, 
                  (struct sockaddr *)&p->addr, &addr_len);
}