4.4  Exemple de serveur 2/2

int initialisationSocketUDP(char *service){
struct addrinfo precisions,*resultat,*origine;
int statut;
int s;

/* Construction de la structure adresse */
memset(&precisions,0,sizeof precisions);
precisions.ai_family=AF_UNSPEC;
precisions.ai_socktype=SOCK_DGRAM;
precisions.ai_flags=AI_PASSIVE;
statut=getaddrinfo(NULL,service,&precisions,&origine);
if(statut<0){ perror("initialisationSocketUDP.getaddrinfo"); exit(EXIT_FAILURE); }
struct addrinfo *p;
for(p=origine,resultat=origine;p!=NULL;p=p->ai_next)
  if(p->ai_family==AF_INET6){ resultat=p; break; }

/* Creation d'une socket */
s=socket(resultat->ai_family,resultat->ai_socktype,resultat->ai_protocol);
if(s<0){ perror("initialisationSocketUDP.socket"); exit(EXIT_FAILURE); }

/* Options utiles */
int vrai=1;
if(setsockopt(s,SOL_SOCKET,SO_REUSEADDR,&vrai,sizeof(vrai))<0){
  perror("initialisationServeurUDPgenerique.setsockopt (REUSEADDR)");
  exit(EXIT_FAILURE);
  }

/* Specification de l'adresse de la socket */
statut=bind(s,resultat->ai_addr,resultat->ai_addrlen);
if(statut<0){
  freeaddrinfo(origine); shutdown(s,SHUT_RDWR);
  perror("initialisationServeurUDP.bind");
  return -1;
  }

/* Liberation de la structure d'informations */
freeaddrinfo(origine);

return s;
}

int boucleServeurUDP(int s,int (*traitement)(unsigned char *,int,struct sockaddr *,int)){
while(1){
  struct sockaddr_storage adresse;
  socklen_t taille=sizeof(adresse);
  unsigned char message[MAX_UDP_MESSAGE];
  int nboctets=recvfrom(s,message,MAX_UDP_MESSAGE,0,(struct sockaddr *)&adresse,&taille);
  if(nboctets<0) return -1;
  if(traitement(message,nboctets,(struct sockaddr *)&adresse,taille)<0) break;
  }
return 0;
}

int main(void){
int s=initialisationSocketUDP("4242");
if(s<0){ fprintf(stderr,"Port non utilisable\n"); exit(EXIT_FAILURE); }
boucleServeurUDP(s,votreFonctionUDP);
shutdown(s,SHUT_RDWR);
return 0;
}