envoi de paquet tcp linux
bonjour,
je tourne sous linux, le problème est lorsque je compile, le message errorn apparrait plein de fois,je débute en programmation réseaux si vous pouvez m'aider car j'arrive pas à envoyer un paque tcp, je pense que le problème vient lors de l'envoie du paquet(dans la boucle à la fin du code)
J'espère avoir été compréhensible je vous passe le code ci-joint,
merci
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| #include<stdio.h>
#include<netinet/tcp.h> //Provides declarations for tcp header
#include<netinet/ip.h> //Provides declarations for ip header
#include <string.h>
//Checksum calculation function
unsigned short csum (unsigned short *buf, int nwords)
{
unsigned long sum;
for (sum = 0; nwords > 0; nwords--)
sum += *buf++;
sum = (sum >> 16) + (sum & 0xffff);
sum += (sum >> 16);
return ~sum;
}
int main (void)
{
//Create a raw socket
int s = socket (PF_INET, SOCK_RAW, IPPROTO_TCP);
//Datagram to represent the packet
char datagram[4096];
//IP header
struct iphdr *iph = (struct iphdr *) datagram;
//TCP header
struct tcphdr *tcph = (struct tcphdr *) (datagram + sizeof (struct ip));
struct sockaddr_in sin;
sin.sin_family = AF_INET;
sin.sin_port = htons(40);
sin.sin_addr.s_addr = inet_addr ("74.125.39.104");
memset (datagram, 0, 4096); /* zero out the buffer */
//Fill in the IP Header
iph->ihl = 5;
iph->version = 4;
iph->tos = 0;
iph->tot_len = sizeof (struct ip) + sizeof (struct tcphdr);
iph->id = htonl (54321); //Id of this packet
iph->frag_off = 0;
iph->ttl = 255;
iph->protocol = 6;
iph->check = 0; //Set to 0 before calculating checksum
iph->saddr = inet_addr ("xx.xx.xx.xx"); //Spoof the source ip address
iph->daddr = sin.sin_addr.s_addr;
//TCP Header
tcph->source = htons (1234);
tcph->dest = htons (85);
tcph->seq = random ();
tcph->ack_seq = 0;
tcph->doff = 0; /* first and only tcp segment */
tcph->syn = 1;
tcph->window = htonl (65535); /* maximum allowed window size */
tcph->check = 0;/* if you set a checksum to zero, your kernel's IP stack
should fill in the correct checksum during transmission */
tcph->urg_ptr = 0;
//Now the IP checksum
iph->check = csum ((unsigned short *) datagram, iph->tot_len >> 1);
//IP_HDRINCL to tell the kernel that headers are included in the packet
{
int one = 1;
const int *val = &one;
if (setsockopt (s, IPPROTO_IP, IP_HDRINCL, val, sizeof (one)) < 0)
printf ("Warning: Cannot set HDRINCL!n");
}
while (1)
{
//Send the packet
if (sendto (s, /* our socket */
datagram, /* the buffer containing headers and data */
iph->tot_len, /* total length of our datagram */
0, /* routing flags, normally always 0 */
(struct sockaddr *) &sin, /* socket addr, just like in */
sizeof (sin)) < 0) /* a normal send() */
printf ("errorn");
else
printf (".");
}
} |
