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| #include <arpa/inet.h>
#include <string.h>
#include <stdio.h>
typedef struct ipheader {
unsigned char hl:4, v:4; /* this means that each member is 4 bits */
unsigned char tos;
unsigned short int len;
unsigned short int id;
unsigned short int off;
unsigned char ttl;
unsigned char p;
unsigned short int sum;
unsigned int src;
unsigned int dst;
} * t_ipheader; /* total ip header length: 20 bytes (=160 bits) */
typedef struct tcpheader {
unsigned short int sport;
unsigned short int dport;
unsigned int seq;
unsigned int ack;
unsigned char x2:4, off:4;
unsigned char flags;
unsigned short int win;
unsigned short int sum;
unsigned short int urp;
} * t_tcpheader; /* total tcp header length: 20 bytes (=160 bits) */
void fill_ipheader(t_ipheader header) {
//t_ipheader header = (t_ipheader) malloc(sizeof(ipheader));
header -> hl = 5; // header is 5 * 32 bits
header -> v = 4; // ip v4
header -> tos = 0; // type of service, don't care
header -> len = sizeof(struct ipheader) + sizeof(struct tcpheader);
header -> id = 0; // id, don't care
header -> off = 0; // first fragment
header -> ttl = 1; // on lan, 1 router, which provide wifi
header -> p = 6; // tcp protocol;
header -> sum = 0;
header -> src = inet_addr("192.168.0.1");
header -> dst = inet_addr("192.168.0.1");
}
void fill_tcpheader(t_tcpheader header) {
//t_tcpheader header = (t_tcpheader) malloc(sizeof(tcpheader));
header -> sport = 1863;
header -> dport = 59575;
header -> seq = 127;
header -> ack = 0;
header -> x2 = 0;
header -> off = 0x8;
header -> flags = 18;
header -> win = 0xfd91;
header -> sum = 0;
header -> urp = 0;
}
int main() {
int s = socket (PF_INET, SOCK_RAW, IPPROTO_TCP);
char datagram[4096];
memset (datagram, 0, 4096);
fill_ipheader((t_ipheader)datagram);
fill_tcpheader((t_tcpheader)(datagram + sizeof(struct ipheader)));
char* offset = datagram + sizeof(struct ipheader) + sizeof(struct tcpheader);
offset[0] = 5;
struct sockaddr_in sin;
sin.sin_family = AF_INET;
sin.sin_port = htons (1863);
sin.sin_addr.s_addr = inet_addr ("192.168.0.1");
{ /* lets do it the ugly way.. */
int one = 1;
const int *val = &one;
if (setsockopt (s, IPPROTO_IP, IP_HDRINCL, val, sizeof (one)) < 0)
printf ("Warning: Cannot set HDRINCL!\n");
}
if (sendto (s, datagram, ((t_ipheader)datagram)->len, 0,
(struct sockaddr *) &sin, sizeof (sin)) < 0)
printf ("error\n");
else
printf (".");
} |
