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| //Générer un paquet IP qui encapsule un paquet ICMP (application un PING)
#include <sys/types.h>
#include <sys/socket.h>
#include <linux/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#include <netdb.h>
#include <string.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <ctype.h>
#include <unistd.h>
unsigned short in_chksum(unsigned short *, int);
int main (int argc, char * argv[])
{
int sock;
int rc;
int num;
struct sockaddr_in addrsock_source;
struct sockaddr_in addrsock_dest;
struct iphdr *ip;
struct icmphdr *icmp;
char *packet;
int psize;
//Syntaxe : adresse
if (argc != 4)
{
perror("Syntaxe : exo1 adresse-source adresse-dest taille");
exit(1);
}
//Recuperation de la taille
psize= atoi(argv[3]); //Taille du packet
//Création de la structure d'adressage
addrsock_source.sin_addr.s_addr = inet_addr(argv[1]); //
Affectation de l'adresse source
addrsock_dest.sin_addr.s_addr = inet_addr(argv[2]); //
Affectation de l'adress dest
addrsock_source.sin_family = AF_INET; //
Connection de type AF_INET
addrsock_dest.sin_family = AF_INET; // Connection de type AF_INET
addrsock_source.sin_port = htons(0);// Port = 0
addrsock_dest.sin_port = htons(0); // Port = 0
//Création de la socket
2
sock = socket(AF_INET, SOCK_RAW, IPPROTO_RAW);
if (sock < 0)
{
perror("Erreur de création de Socket");
exit(-1);
}
//Generation d'un espace mémoire de la taille du paquet (en tete IP + en tete
ICMP + données)
packet = malloc(sizeof(struct iphdr) + sizeof (struct icmphdr) + psize);
ip = (struct iphdr *) packet;
icmp = (struct icmphdr *) (packet + sizeof(struct iphdr));
// Mise à 0 de tous le bloc mémoire
memset(packet, 0, sizeof(struct iphdr) + sizeof(struct icmphdr) + psize);
// Définition des champs des trames IP & ICMP
ip->tot_len = htons(sizeof(struct iphdr) + sizeof(struct icmphdr) + psize);
ip->ihl = 5;
ip->version = 4;
ip->ttl = 255;
ip->tos = 0;
ip->frag_off = 0;
ip->protocol = IPPROTO_ICMP;
ip->saddr = addrsock_source.sin_addr.s_addr;
ip->daddr = addrsock_dest.sin_addr.s_addr;
ip->check = in_chksum((unsigned short *)ip, sizeof(struct iphdr));
icmp->type = 8;
icmp->code = 0;
icmp->checksum = in_chksum((unsigned short *)icmp, sizeof(struct icmphdr) +
psize);
// Envoi de la trame
rc=sendto(sock, packet, sizeof(struct iphdr) + sizeof(struct icmphdr) +
psize, 0, (struct sockaddr *)&addrsock_dest, sizeof(struct sockaddr));
printf("Nombre de bits transmis : %d\n",rc);
// Liberation de la mémoire
// free(packet);
}
unsigned short in_chksum (unsigned short *addr, int len)
{
register int nleft = len;
register int sum = 0;
u_short answer = 0;
while (nleft > 1)
{
sum += *addr++;
nleft -= 2;
}
if (nleft == 1)
{
*(u_char *)(&answer) = *(u_char *)addr;
sum += answer;
}
sum = (sum >> 16) + (sum + 0xffff);
sum += (sum >> 16);
answer = ~sum;
return(answer);} |
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