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safchain/pktgen Secret

Last active Jun 12, 2020
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#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <stdlib.h>
#include <errno.h>
#include <netinet/tcp.h>
#include <netinet/ip.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/time.h>
#include <signal.h>
extern char *optarg;
struct pseudo_header //needed for checksum calculation
{
unsigned int saddr;
unsigned int daddr;
unsigned char placeholder;
unsigned char protocol;
unsigned short length;
struct tcphdr tcp;
};
unsigned short csum(unsigned short *ptr, int n)
{
long sum = 0;
unsigned short oddbyte;
unsigned short answer;
while (n > 1)
{
sum += *ptr++;
n -= 2;
}
if (n == 1)
{
oddbyte = 0;
*((char *)&oddbyte) = *(char *)ptr;
sum += oddbyte;
}
sum = (sum >> 16) + (sum & 0xffff);
sum += (sum >> 16);
answer = ~sum;
return answer;
}
unsigned long npackets = 0;
void timer_handler(int signum)
{
printf("%d packets sent\n", npackets);
exit(0);
}
void usage()
{
printf("usage: yapktgen -s <source ip> -d <dest ip> -p <payload size> -d <duration in sec>\n");
exit(1);
}
int main(int argc, char **argv)
{
char datagram[65536], sip[16], dip[16];
struct iphdr *iph = (struct iphdr *)datagram;
struct tcphdr *tcph = (struct tcphdr *)(datagram + sizeof(struct ip));
struct sockaddr_in sin;
struct pseudo_header psh;
int opt, sock, payload = 1024, duration = 10;
struct itimerval timer;
while ((opt = getopt(argc, argv, "s:d:p:t:")) != -1)
{
switch (opt)
{
case 's':
strcpy(sip, optarg);
break;
case 'd':
strcpy(dip, optarg);
break;
case 'p':
payload = atoi(optarg);
break;
case 't':
duration = atoi(optarg);
break;
default:
fprintf(stderr, "Unknow option !");
usage();
}
}
if (sip == NULL || dip == NULL)
{
usage();
}
sock = socket(PF_INET, SOCK_RAW, IPPROTO_TCP);
memset(datagram, 0, 65536);
iph->ihl = 5;
iph->version = 4;
iph->tot_len = sizeof(struct ip) + sizeof(struct tcphdr) + payload;
iph->id = htons(54321);
iph->ttl = 255;
iph->protocol = IPPROTO_TCP;
iph->saddr = inet_addr(sip);
iph->daddr = inet_addr(dip);
iph->check = csum((unsigned short *)datagram, iph->tot_len >> 1);
tcph->doff = 5;
tcph->syn = 1;
tcph->window = htons(5840);
psh.saddr = iph->saddr;
psh.daddr = iph->daddr;
psh.placeholder = 0;
psh.protocol = IPPROTO_TCP;
psh.length = htons(20);
memcpy(&psh.tcp, tcph, sizeof(struct tcphdr));
int value = 1;
if (setsockopt(sock, IPPROTO_IP, IP_HDRINCL, &value, sizeof(value)) < 0)
{
fprintf(stderr, "Error %s\n", strerror(errno));
exit(1);
}
sin.sin_family = AF_INET;
sin.sin_addr.s_addr = iph->daddr;
/* Install timer_handler as the signal handler for SIGVTALRM. */
if (signal(SIGALRM, timer_handler) == SIG_ERR)
{
fprintf(stderr, "Error %s\n", strerror(errno));
exit(1);
}
timer.it_value.tv_sec = duration;
timer.it_value.tv_usec = 0;
timer.it_interval.tv_sec = 0;
timer.it_interval.tv_usec = 0;
printf("Start injection for :%d sec\n", duration);
setitimer(ITIMER_REAL, &timer, NULL);
unsigned long ports = 1;
while (1)
{
int port1 = ports & 0xffff;
int port2 = (ports >> 16) & 0xffff;
tcph->source = htons(port1 > 0 ? port1 : 1);
tcph->dest = htons(port2 > 0 ? port2 : 1);
tcph->check = csum((unsigned short *)&psh, sizeof(struct pseudo_header));
sin.sin_port = tcph->dest;
if (sendto(sock, datagram, iph->tot_len, 0, (struct sockaddr *)&sin, sizeof(sin)) < 0)
{
fprintf(stderr, "Error %s\n", strerror(errno));
exit(1);
}
npackets++;
ports++;
}
return 0;
}
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