A.3  Programmation en mode non connecté

A.3.1  Exemple de serveur

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(-1);
  }

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

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

return s;
}

int boucleServeurUDP(int s,int (*traitement)(unsigned char *,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)<0) break;
  }
return 0;
}

int main(void){
int s=initialisationSocketUDP("4242");
boucleServeurUDP(s,votreFonctionUDP);
shutdown(s,SHUT_RDWR);
return 0;
}

A.3.2  Exemple de client

void messageUDP(char *hote,char *service,unsigned char *message,int taille){
struct addrinfo precisions,*resultat,*origine;
int statut;
int s;

/* Creation de l'adresse de socket */
memset(&precisions,0,sizeof precisions);
precisions.ai_family=AF_UNSPEC;
precisions.ai_socktype=SOCK_DGRAM;
statut=getaddrinfo(hote,service,&precisions,&origine);
if(statut<0){ perror("messageUDPgenerique.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("messageUDPgenerique.socket"); exit(EXIT_FAILURE); }

/* Option sur la socket */
int vrai=1;
if(setsockopt(s,SOL_SOCKET,SO_BROADCAST,&vrai,sizeof(vrai))<0){
  perror("initialisationServeurUDPgenerique.setsockopt (BROADCAST)");
  exit(-1);
  }

/* Envoi du message */
int nboctets=sendto(s,message,taille,0,resultat->ai_addr,resultat->ai_addrlen);
if(nboctets<0){ perror("messageUDPgenerique.sento"); exit(EXIT_FAILURE); }

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

/* Fermeture de la socket d'envoi */
close(s);
}

int main(int argc,char *argv[]){
if(argc!=3){
  fprintf(stderr,"Syntaxe : %s <serveur> <message>\n",argv[0]);
  exit(EXIT_FAILURE);
  }
char *hote=argv[1];
char *message=argv[2];
char *service="4000";
messageUDP(hote,service,(unsigned char *)message,strlen(message));
return 0;
}